fix(run): list an Add Service category once (#2175)

The Add Service menu grouped the project's kinds and the remaining kinds separately, so a category the project used only partly, such as Build Tools, appeared in both sections. A category now appears once, in the project section when the project uses any of its kinds.

Cargo.lock

@@ -3907,6 +3907,12 @@ version = "1.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6dbf3de79e51f3d586ab4cb9d5c3e2c14aa28ed23d180cf89b4df0454a69cc87"
 
+[[package]]
+name = "httpdate"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df3b46402a9d5adb4c86a0cf463f42e19994e3ee891101b1841f30a545cb49a9"
+
 [[package]]
 name = "hybrid-array"
 version = "0.4.15"
@@ -3933,6 +3939,7 @@ dependencies = [
  "http",
  "http-body",
  "httparse",
+ "httpdate",
  "itoa",
  "pin-project-lite",
  "smallvec",
@@ -4106,12 +4113,13 @@ checksum = "3d3067d79b975e8844ca9eb072e16b31c3c1c36928edf9c6789548c524d0d954"
 
 [[package]]
 name = "ide-agent"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "dunce",
  "encoding_rs",
  "ide-core",
  "ide-jsonrpc",
+ "ide-mcp",
  "ide-tools",
  "ide-vcs",
  "ide-vfs",
@@ -4129,7 +4137,7 @@ dependencies = [
 
 [[package]]
 name = "ide-analysis"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ast-grep-core",
  "ide-core",
@@ -4143,7 +4151,7 @@ dependencies = [
 
 [[package]]
 name = "ide-android"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ide-core",
  "serde",
@@ -4154,7 +4162,7 @@ dependencies = [
 
 [[package]]
 name = "ide-build"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "blake3",
  "dirs 6.0.0",
@@ -4168,9 +4176,23 @@ dependencies = [
  "zip",
 ]
 
+[[package]]
+name = "ide-cli"
+version = "0.1.39"
+dependencies = [
+ "dirs 6.0.0",
+ "serde",
+ "serde_json",
+ "tempfile",
+ "tokio",
+ "tracing",
+ "windows-sys 0.61.2",
+ "winreg 0.56.0",
+]
+
 [[package]]
 name = "ide-clipboard"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "objc2 0.6.5",
  "objc2-app-kit 0.3.2",
@@ -4179,7 +4201,7 @@ dependencies = [
 
 [[package]]
 name = "ide-core"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "dunce",
  "encoding_rs",
@@ -4196,7 +4218,7 @@ dependencies = [
 
 [[package]]
 name = "ide-coverage"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ide-core",
  "ide-run",
@@ -4210,7 +4232,7 @@ dependencies = [
 
 [[package]]
 name = "ide-dap"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "futures",
  "ide-core",
@@ -4231,7 +4253,7 @@ dependencies = [
 
 [[package]]
 name = "ide-db"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "bb8",
  "dirs 6.0.0",
@@ -4258,7 +4280,7 @@ dependencies = [
 
 [[package]]
 name = "ide-docker"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ide-core",
  "serde",
@@ -4271,7 +4293,7 @@ dependencies = [
 
 [[package]]
 name = "ide-extension"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "base64 0.22.1",
  "blake3",
@@ -4291,7 +4313,7 @@ dependencies = [
 
 [[package]]
 name = "ide-fonts"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "objc2-core-foundation",
  "objc2-core-text",
@@ -4303,7 +4325,7 @@ dependencies = [
 
 [[package]]
 name = "ide-github"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ide-core",
  "ide-vcs",
@@ -4316,7 +4338,7 @@ dependencies = [
 
 [[package]]
 name = "ide-host"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "base64 0.22.1",
  "blake3",
@@ -4324,6 +4346,7 @@ dependencies = [
  "dirs 6.0.0",
  "dunce",
  "encoding_rs",
+ "futures",
  "getrandom 0.3.4",
  "globset",
  "ide-agent",
@@ -4340,6 +4363,7 @@ dependencies = [
  "ide-jsonrpc",
  "ide-language",
  "ide-lsp",
+ "ide-mcp",
  "ide-notebook",
  "ide-plugin",
  "ide-remote",
@@ -4358,6 +4382,7 @@ dependencies = [
  "ignore",
  "parking_lot",
  "quick-xml 0.42.0",
+ "regex-lite",
  "regex-syntax",
  "reqwest",
  "rustix",
@@ -4378,7 +4403,7 @@ dependencies = [
 
 [[package]]
 name = "ide-http"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ide-core",
  "parking_lot",
@@ -4396,7 +4421,7 @@ dependencies = [
 
 [[package]]
 name = "ide-index"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "blake3",
  "criterion",
@@ -4418,7 +4443,7 @@ dependencies = [
 
 [[package]]
 name = "ide-jsonrpc"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "encoding_rs",
  "futures",
@@ -4435,7 +4460,7 @@ dependencies = [
 
 [[package]]
 name = "ide-language"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "blake3",
  "criterion",
@@ -4491,7 +4516,7 @@ dependencies = [
 
 [[package]]
 name = "ide-lsp"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "dunce",
  "futures",
@@ -4515,9 +4540,28 @@ dependencies = [
  "zip",
 ]
 
+[[package]]
+name = "ide-mcp"
+version = "0.1.39"
+dependencies = [
+ "bytes",
+ "dunce",
+ "getrandom 0.3.4",
+ "http-body-util",
+ "hyper",
+ "hyper-util",
+ "percent-encoding",
+ "serde",
+ "serde_json",
+ "tempfile",
+ "tokio",
+ "tokio-util",
+ "tracing",
+]
+
 [[package]]
 name = "ide-notebook"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "futures",
  "ide-core",
@@ -4540,7 +4584,7 @@ dependencies = [
 
 [[package]]
 name = "ide-plugin"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "blake3",
  "ide-core",
@@ -4561,7 +4605,7 @@ dependencies = [
 
 [[package]]
 name = "ide-profiler"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ide-core",
  "ide-run",
@@ -4574,7 +4618,7 @@ dependencies = [
 
 [[package]]
 name = "ide-remote"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "globset",
  "ide-core",
@@ -4592,7 +4636,7 @@ dependencies = [
 
 [[package]]
 name = "ide-run"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "dunce",
  "encoding_rs",
@@ -4616,7 +4660,7 @@ dependencies = [
 
 [[package]]
 name = "ide-sdk"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "dunce",
  "ide-core",
@@ -4635,7 +4679,7 @@ dependencies = [
 
 [[package]]
 name = "ide-search"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "criterion",
  "globset",
@@ -4655,7 +4699,7 @@ dependencies = [
 
 [[package]]
 name = "ide-spell"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ide-core",
  "parking_lot",
@@ -4668,7 +4712,7 @@ dependencies = [
 
 [[package]]
 name = "ide-ssh"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "dirs 6.0.0",
  "flate2",
@@ -4689,7 +4733,7 @@ dependencies = [
 
 [[package]]
 name = "ide-syntax"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ide-core",
  "ide-language",
@@ -4704,7 +4748,7 @@ dependencies = [
 
 [[package]]
 name = "ide-terminal"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ide-core",
  "libc",
@@ -4717,7 +4761,7 @@ dependencies = [
 
 [[package]]
 name = "ide-text"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "criterion",
  "ide-core",
@@ -4730,7 +4774,7 @@ dependencies = [
 
 [[package]]
 name = "ide-tools"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "flate2",
  "hex",
@@ -4751,7 +4795,7 @@ dependencies = [
 
 [[package]]
 name = "ide-vcs"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "blake3",
  "dunce",
@@ -4772,7 +4816,7 @@ dependencies = [
 
 [[package]]
 name = "ide-vfs"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "chardetng",
  "dunce",
@@ -4796,7 +4840,7 @@ dependencies = [
 
 [[package]]
 name = "ide-web"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "ide-core",
  "open",
@@ -4812,7 +4856,7 @@ dependencies = [
 
 [[package]]
 name = "ide-workspace"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "blake3",
  "dunce",
@@ -6358,7 +6402,7 @@ dependencies = [
 
 [[package]]
 name = "openidea"
-version = "0.1.38"
+version = "0.1.39"
 dependencies = [
  "base64 0.22.1",
  "blake3",
@@ -6370,6 +6414,7 @@ dependencies = [
  "ide-analysis",
  "ide-android",
  "ide-build",
+ "ide-cli",
  "ide-clipboard",
  "ide-core",
  "ide-coverage",
@@ -6385,6 +6430,7 @@ dependencies = [
  "ide-jsonrpc",
  "ide-language",
  "ide-lsp",
+ "ide-mcp",
  "ide-notebook",
  "ide-plugin",
  "ide-profiler",

Cargo.toml

@@ -5,7 +5,7 @@ members = ["crates/*", "src-tauri"]
 exclude = ["sdk", "plugins"]
 
 [workspace.package]
-version = "0.1.38"
+version = "0.1.39"
 edition = "2024"
 rust-version = "1.96"
 license = "Apache-2.0"
@@ -42,9 +42,11 @@ ide-fonts = { path = "crates/ide-fonts" }
 ide-ssh = { path = "crates/ide-ssh" }
 ide-remote = { path = "crates/ide-remote" }
 ide-host = { path = "crates/ide-host" }
+ide-mcp = { path = "crates/ide-mcp" }
 ide-notebook = { path = "crates/ide-notebook" }
 ide-extension = { path = "crates/ide-extension" }
 ide-plugin = { path = "crates/ide-plugin" }
+ide-cli = { path = "crates/ide-cli" }
 
 # serialization & IPC typing
 serde = { version = "1", features = ["derive"] }

crates/ide-agent/Cargo.toml

@@ -9,6 +9,7 @@ license.workspace = true
 encoding_rs.workspace = true
 ide-vfs.workspace = true
 ide-core.workspace = true
+ide-mcp.workspace = true
 ide-jsonrpc.workspace = true
 ide-vcs.workspace = true
 ide-tools = { path = "../ide-tools" }
@@ -21,7 +22,5 @@ tracing.workspace = true
 parking_lot.workspace = true
 dunce.workspace = true
 uuid.workspace = true
-which = "8"
-
-[dev-dependencies]
 tempfile.workspace = true
+which = "8"

crates/ide-agent/src/acp/mod.rs

@@ -27,6 +27,29 @@ use std::sync::Arc;
 use std::sync::atomic::{AtomicU8, Ordering};
 use tokio::sync::oneshot;
 
+/// ACP's error code for a request that needs the user to sign in.
+pub(crate) const AUTH_REQUIRED: i64 = -32000;
+
+// Covers signed-out users and refused accounts (Claude Code: "API Error: 403").
+pub(crate) fn auth_required(code: i64, message: &str) -> bool {
+    if code == AUTH_REQUIRED {
+        return true;
+    }
+    let lower = message.to_lowercase();
+    let words: Vec<&str> = lower.split(|c: char| !c.is_alphanumeric()).filter(|w| !w.is_empty()).collect();
+    words.iter().any(|w| {
+        *w == "auth"
+            || w.starts_with("authenticat")
+            || w.starts_with("authoriz")
+            || w.starts_with("unauthenticat")
+            || w.starts_with("unauthoriz")
+            || w.starts_with("oauth")
+    }) || words.windows(3).any(|w| w == ["not", "logged", "in"])
+        || words
+            .windows(2)
+            .any(|w| w == ["logged", "out"] || w == ["sign", "in"] || w == ["log", "in"] || w == ["login", "required"])
+}
+
 /// The capabilities this client offers, in v1 form.
 fn client_capabilities() -> Value {
     json!({
@@ -69,6 +92,11 @@ pub(crate) struct Negotiated {
 }
 
 impl Negotiated {
+    pub fn mcp_stdio(&self) -> bool {
+        // Stdio is the ACP v1 baseline; v2 negotiates each transport explicitly.
+        self.capabilities.pointer("/mcpCapabilities/stdio").and_then(Value::as_bool).unwrap_or(self.generation == 1)
+    }
+
     /// Reads an `initialize` response. The shape decides, not `protocolVersion`: some v1
     /// agents report version 2 with v1 fields (`agentInfo`, `agentCapabilities`); only a
     /// v2 response has `info`.
@@ -97,7 +125,7 @@ impl Negotiated {
                 "audio": has(prompt, "audio"),
                 "embeddedContext": has(prompt, "embeddedContext"),
             },
-            "mcpCapabilities": { "http": has(mcp, "http"), "sse": false },
+            "mcpCapabilities": { "http": has(mcp, "http"), "sse": false, "stdio": has(mcp, "stdio") },
         });
         if session.is_some() {
             let mut sc = json!({ "list": {}, "resume": {}, "close": {} });

crates/ide-agent/src/acp/tests.rs

@@ -16,6 +16,42 @@ const CANCEL: &str = include_str!("../../tests/fixtures/acp-v2/cancel.jsonl");
 const RESUME: &str = include_str!("../../tests/fixtures/acp-v2/resume.jsonl");
 const INITIALIZE_V1: &str = include_str!("../../tests/fixtures/acp-v2/initialize-v1.jsonl");
 
+#[test]
+fn auth_required_matches_authentication_words_and_sign_in_phrases() {
+    for (code, message, expected) in [
+        (AUTH_REQUIRED, "This account is not eligible.", true),
+        (codes::INTERNAL_ERROR, "Auth required", true),
+        (codes::INTERNAL_ERROR, "Authentication failed", true),
+        (codes::INTERNAL_ERROR, "Failed to authenticate. API Error: 401", true),
+        (codes::INTERNAL_ERROR, "Failed to authenticate. API Error: 403", true),
+        (codes::INTERNAL_ERROR, "Not authenticated", true),
+        (codes::INTERNAL_ERROR, "Authorization failed", true),
+        (codes::INTERNAL_ERROR, "Authorize your account", true),
+        (codes::INTERNAL_ERROR, "Unauthenticated", true),
+        (codes::INTERNAL_ERROR, "Unauthentication error", true),
+        (codes::INTERNAL_ERROR, "Unauthorized", true),
+        (codes::INTERNAL_ERROR, "Unauthorization error", true),
+        (codes::INTERNAL_ERROR, "OAuth token has expired", true),
+        (codes::INTERNAL_ERROR, "OAuth2 token has expired", true),
+        (codes::INTERNAL_ERROR, "You are not logged in", true),
+        (codes::INTERNAL_ERROR, "You are logged out", true),
+        (codes::INTERNAL_ERROR, "Please sign in", true),
+        (codes::INTERNAL_ERROR, "Please log in", true),
+        (codes::INTERNAL_ERROR, "Login required", true),
+        (codes::INTERNAL_ERROR, "author", false),
+        (codes::INTERNAL_ERROR, "authors", false),
+        (codes::INTERNAL_ERROR, "authority", false),
+        (codes::INTERNAL_ERROR, "authored", false),
+        (codes::INTERNAL_ERROR, "reauthenticate", false),
+        (codes::INTERNAL_ERROR, "preauthorized", false),
+        (codes::INTERNAL_ERROR, "signal input failed", false),
+        (codes::INTERNAL_ERROR, "catalog index failed", false),
+        (codes::INTERNAL_ERROR, "login succeeded", false),
+    ] {
+        assert_eq!(auth_required(code, message), expected, "code={code}, message={message:?}");
+    }
+}
+
 /// The messages of a fixture going `dir` (`in` or `out`).
 pub(crate) fn frames(fixture: &str, dir: &str) -> Vec<Value> {
     fixture
@@ -527,3 +563,13 @@ async fn v1_requests_are_sent_in_v2() {
         .collect();
     assert_eq!(commands, [&json!("28846a4c-c3e8-4a45-a3d0-c19f10d19d1a"), &json!("s1")]);
 }
+
+#[test]
+fn stdio_mcp_is_v1_baseline_and_negotiated_in_v2() {
+    assert!(super::Negotiated::from_initialize(&json!({"protocolVersion":1,"agentCapabilities":{}})).mcp_stdio());
+    assert!(!super::Negotiated::from_initialize(&json!({"info":{},"capabilities":{"session":{}}})).mcp_stdio());
+    assert!(
+        super::Negotiated::from_initialize(&json!({"info":{},"capabilities":{"session":{"mcp":{"stdio":{}}}}}))
+            .mcp_stdio()
+    );
+}

crates/ide-agent/src/config.rs

@@ -2,7 +2,8 @@
 //! the agent reports them over ACP.
 
 use crate::model::{
-    AgentCommand, AgentConfigOption, AgentConfigValue, AgentConfigVia, AgentCost, AgentLimit, AgentUsage,
+    AgentCommand, AgentCommandSource, AgentConfigOption, AgentConfigValue, AgentConfigVia, AgentCost, AgentLimit,
+    AgentUsage,
 };
 use serde_json::{Value, json};
 
@@ -35,20 +36,32 @@ pub(crate) fn add_client_options(provider: &str, config: &mut Vec<AgentConfigOpt
     });
 }
 
-pub(crate) fn bypass_approvals(provider: &str, config: &[AgentConfigOption]) -> bool {
-    provider == "cursor" && config.iter().any(|o| o.id == CURSOR_APPROVAL && o.current.as_deref() == Some("bypass"))
+/// Whether the current settings approve tool requests without asking: a bypass mode,
+/// an allow-all permissions option, or a bypass approval policy.
+pub(crate) fn bypass_approvals(config: &[AgentConfigOption]) -> bool {
+    let selected = |category: &str| {
+        config.iter().find(|o| o.category.as_deref() == Some(category)).and_then(|o| o.current.as_deref())
+    };
+    selected("mode").is_some_and(is_bypass_mode)
+        || selected("permissions").is_some_and(|v| matches!(v.to_ascii_lowercase().as_str(), "on" | "true"))
+        || selected("approval").is_some_and(|v| v.eq_ignore_ascii_case("bypass"))
 }
 
 /// The mode that approves everything without asking (`bypassPermissions`, `yolo`, `full-access`…), if the agent has one.
 pub(crate) fn bypass_mode(options: &[AgentConfigOption]) -> Option<(&AgentConfigOption, &AgentConfigValue)> {
     let option = options.iter().find(|o| o.category.as_deref() == Some("mode"))?;
-    let value = option.values.iter().find(|v| {
-        let m: String = v.value.to_lowercase().chars().filter(char::is_ascii_lowercase).collect();
-        m.contains("bypass") || m == "yolo" || m.contains("fullaccess") || m == "dangerous"
-    })?;
+    let value = option.values.iter().find(|v| is_bypass_mode(&v.value))?;
     Some((option, value))
 }
 
+fn is_bypass_mode(mode: &str) -> bool {
+    // Mode ids can be URL-like (`…/session-modes#yolo`), as the composer's mode icon also assumes.
+    let lower = mode.to_lowercase();
+    let m: String =
+        lower.rsplit(['#', '/']).next().unwrap_or_default().chars().filter(char::is_ascii_lowercase).collect();
+    m.contains("bypass") || m == "yolo" || m.contains("fullaccess") || m == "dangerous"
+}
+
 /// The settings in a `session/new` or `session/load` result: its select `configOptions`,
 /// plus the older `modes` / `models` fields for what those don't cover.
 pub(crate) fn options_of(result: &Value) -> Vec<AgentConfigOption> {
@@ -133,15 +146,22 @@ pub(crate) fn set_request(option: &AgentConfigOption, value: &str) -> (&'static
 }
 
 /// `available_commands_update`.
-pub(crate) fn commands_of(update: &Value) -> Vec<AgentCommand> {
+pub(crate) fn commands_of(update: &Value, provider: &str) -> Vec<AgentCommand> {
     update
         .get("availableCommands")
         .and_then(Value::as_array)
         .into_iter()
         .flatten()
         .filter_map(|c| {
+            let name = c.get("name")?.as_str()?.trim_start_matches('/');
+            let source = if provider == "codex-acp" && name.starts_with('$') {
+                AgentCommandSource::Skill
+            } else {
+                c.get("source").and_then(|s| serde_json::from_value(s.clone()).ok()).unwrap_or_default()
+            };
             Some(AgentCommand {
-                name: c.get("name")?.as_str()?.trim_start_matches('/').to_owned(),
+                name: name.to_owned(),
+                source,
                 description: str_of(c, "description").unwrap_or_default(),
                 hint: c.pointer("/input/hint").and_then(Value::as_str).filter(|h| !h.is_empty()).map(str::to_owned),
             })
@@ -267,12 +287,85 @@ mod tests {
         assert_eq!(ids(&c), [("model", Some("b")), ("mode", Some("code"))]);
     }
 
+    #[test]
+    fn selected_bypass_settings_approve_without_asking() {
+        let full_access = options_of(&json!({
+            "modes": {"currentModeId": "full-access", "availableModes": [
+                {"id": "ask", "name": "Ask"}, {"id": "full-access", "name": "Full Access"}
+            ]}
+        }));
+        assert!(bypass_approvals(&full_access));
+        assert_eq!(bypass_mode(&full_access).map(|(_, v)| v.value.as_str()), Some("full-access"));
+
+        let asking = options_of(&json!({
+            "modes": {"currentModeId": "ask", "availableModes": [
+                {"id": "ask", "name": "Ask"}, {"id": "full-access", "name": "Full Access"}
+            ]}
+        }));
+        assert!(!bypass_approvals(&asking));
+        assert_eq!(
+            bypass_mode(&asking).map(|(_, v)| v.value.as_str()),
+            Some("full-access"),
+            "the offered bypass mode stays available"
+        );
+
+        let permissions = |current: &str| {
+            options_of(&json!({"configOptions": [{
+                "id": "allow_all", "name": "Allow All", "category": "permissions", "type": "select",
+                "currentValue": current, "options": [{"value": "off"}, {"value": "on"}]
+            }]}))
+        };
+        assert!(bypass_approvals(&permissions("on")));
+        assert!(bypass_approvals(&permissions("TRUE")));
+        assert!(!bypass_approvals(&permissions("off")));
+
+        let approval = options_of(&json!({"configOptions": [{
+            "id": "approval", "name": "Approvals", "category": "approval", "type": "select",
+            "currentValue": "bypass", "options": [{"value": "ask"}, {"value": "bypass"}]
+        }]}));
+        assert!(bypass_approvals(&approval));
+
+        // The composer's mode icon splits URL-like ids on `#` / `/`; the backend must agree.
+        let url_mode = options_of(&json!({
+            "modes": {"currentModeId": "https://agentclientprotocol.com/protocol/session-modes#yolo",
+                      "availableModes": [{"id": "https://agentclientprotocol.com/protocol/session-modes#yolo"}]}
+        }));
+        assert!(bypass_approvals(&url_mode));
+    }
+
+    #[test]
+    fn command_sources_in_updates_and_stored_tasks() {
+        let update = json!({"availableCommands": [
+            {"name": "review", "source": "skill"},
+            {"name": "$lint"},
+            {"name": "compact"}
+        ]});
+        let sources = |provider| commands_of(&update, provider).into_iter().map(|c| c.source).collect::<Vec<_>>();
+        assert_eq!(
+            sources("codex-acp"),
+            [AgentCommandSource::Skill, AgentCommandSource::Skill, AgentCommandSource::Command]
+        );
+        assert_eq!(
+            sources("custom"),
+            [AgentCommandSource::Skill, AgentCommandSource::Command, AgentCommandSource::Command]
+        );
+        let old: AgentCommand =
+            serde_json::from_value(json!({"name": "review", "description": "Review", "hint": null})).unwrap();
+        assert_eq!(old.source, AgentCommandSource::Command);
+        let skill = AgentCommand { source: AgentCommandSource::Skill, ..old };
+        assert_eq!(serde_json::from_value::<AgentCommand>(serde_json::to_value(&skill).unwrap()).unwrap(), skill);
+    }
+
     #[test]
     fn commands_and_usage() {
-        let cmds = commands_of(&json!({"availableCommands": [
-            {"name": "review", "description": "Review changes", "input": {"hint": "what to review"}},
-            {"name": "/init", "description": "Write CLAUDE.md", "input": null}
-        ]}));
+        let cmds = commands_of(
+            &json!({"availableCommands": [
+                {"name": "review", "description": "Review changes", "input": {"hint": "what to review"}},
+                {"name": "/init", "description": "Write CLAUDE.md", "input": null}
+            ]}),
+            "claude",
+        );
+        assert_eq!(cmds[0].source, AgentCommandSource::Command);
         assert_eq!(cmds[0].hint.as_deref(), Some("what to review"));
         assert_eq!((cmds[1].name.as_str(), cmds[1].hint.as_ref()), ("init", None));
         let u = usage_of(&json!({"used": 1200, "size": 200000, "cost": {"amount": 0.42, "currency": "USD"}})).unwrap();

crates/ide-agent/src/lib.rs

@@ -100,6 +100,8 @@ struct Shared {
     providers: RwLock<Vec<provider::ProviderSpec>>,
     /// Last probe of each provider.
     probes: Mutex<HashMap<String, AgentProbe>>,
+    /// One pre-session command lookup per provider, including failed attempts.
+    command_fetches: Mutex<HashMap<String, tokio::sync::watch::Receiver<bool>>>,
     /// [`IDLE_RELEASE`], in milliseconds (shorter in tests).
     idle_release_ms: AtomicU64,
 }
@@ -151,6 +153,40 @@ impl Shared {
         cache.get(provider).and_then(|k| k.commands.get(&self.root_key())).cloned().unwrap_or_default()
     }
 
+    async fn fetch_commands(self: &Arc<Self>, spec: provider::ProviderSpec) {
+        let mut ready = {
+            let mut fetches = self.command_fetches.lock();
+            fetches
+                .entry(spec.id.clone())
+                .or_insert_with(|| {
+                    let (done, ready) = tokio::sync::watch::channel(false);
+                    let shared = self.clone();
+                    // Keep the lookup alive if a composer unmounts while it is waiting.
+                    self.runtime.spawn(async move {
+                        if let Ok(commands) =
+                            native::claude::commands(spec.clone(), shared.paths.project_root.clone()).await
+                        {
+                            let commands = config::commands_of(&json!({ "availableCommands": commands }), &spec.id);
+                            let _ = tokio::task::spawn_blocking(move || {
+                                if shared.known_commands(&spec.id).is_empty() {
+                                    shared.remember(&spec.id, None, Some(&commands), None);
+                                }
+                            })
+                            .await;
+                        }
+                        let _ = done.send(true);
+                    });
+                    ready
+                })
+                .clone()
+        };
+        while !*ready.borrow_and_update() {
+            if ready.changed().await.is_err() {
+                break;
+            }
+        }
+    }
+
     fn root_key(&self) -> String {
         self.paths.project_root.to_string_lossy().into_owned()
     }
@@ -251,6 +287,7 @@ struct Live {
     embedded: bool,
     /// `session/load`: the process can be stopped between turns and the session reloaded.
     resumable: bool,
+    mcp_stdio: bool,
 }
 
 struct Task {
@@ -316,6 +353,7 @@ impl AgentManager {
             known: Mutex::new(known),
             providers,
             probes: Mutex::new(HashMap::new()),
+            command_fetches: Mutex::new(HashMap::new()),
             idle_release_ms: AtomicU64::new(IDLE_RELEASE.as_millis() as u64),
         });
         let mut tasks = HashMap::new();
@@ -419,9 +457,21 @@ impl AgentManager {
         // Commands the agent implements itself and never lists (its CLI builtins):
         // merged without duplicating what `availableCommands` or the disk offer.
         let mut offered = offered;
+        if task.is_none()
+            && offered.is_empty()
+            && let Some(spec) = self.shared.spec(&provider).filter(|s| s.driver == provider::Driver::Claude)
+        {
+            self.shared.fetch_commands(spec).await;
+            offered = self.shared.known_commands(&provider);
+        }
         for &(name, description) in builtin_commands(&provider) {
             if !offered.iter().any(|c| c.name == name) {
-                offered.push(AgentCommand { name: name.to_owned(), description: description.to_owned(), hint: None });
+                offered.push(AgentCommand {
+                    name: name.to_owned(),
+                    description: description.to_owned(),
+                    hint: None,
+                    source: AgentCommandSource::Command,
+                });
             }
         }
         if provider != "claude" && provider != "claude-acp" {
@@ -696,7 +746,7 @@ impl AgentManager {
         let cwd_s = dunce::canonicalize(&cwd).unwrap_or(cwd).to_string_lossy().into_owned();
         let reply: Value = live
             .peer
-            .request("session/fork", json!({ "sessionId": live.session, "cwd": cwd_s, "mcpServers": [] }), None)
+            .request("session/fork", json!({ "sessionId": live.session, "cwd": cwd_s, "mcpServers": mcp_servers_for(live.mcp_stdio, &source.shared.paths.project_root) }), None)
             .await
             .map_err(|e| IdeError::internal(source.describe(e)))?;
         let session = reply
@@ -1394,13 +1444,22 @@ impl Task {
             };
             return Failure { message, limit: Some(resets) };
         }
-        match e {
-            // Signed out, or the account was refused (Claude Code: "API Error: 403").
-            RpcError::Server { message, .. } if message.to_lowercase().contains("auth") => {
-                Failure::from(self.live.lock().as_ref().map(|live| live.sign_in_message.clone()).unwrap_or(message))
-            }
-            e => Failure::from(self.describe(e)),
+        let guidance = self.live.lock().as_ref().map(|live| live.sign_in_message.clone());
+        Failure::from(self.sign_in_error(&e, guidance.as_deref()).unwrap_or_else(|| self.describe(e)))
+    }
+
+    fn sign_in_error(&self, e: &RpcError, guidance: Option<&str>) -> Option<String> {
+        let RpcError::Server { code, message, .. } = e else { return None };
+        if !acp::auth_required(*code, message) {
+            return None;
         }
+        tracing::warn!(task = %self.id, code, %message, "agent sign-in failed");
+        let Some(guidance) = guidance else { return Some(message.clone()) };
+        Some(if message.trim().is_empty() || guidance.contains(message) {
+            guidance.to_owned()
+        } else {
+            format!("{guidance}\n\n{message}")
+        })
     }
 
     async fn ensure_session(self: &Arc<Self>) -> Result<Live, String> {
@@ -1419,7 +1478,6 @@ impl Task {
         let spec = tokio::task::spawn_blocking(move || spec.resolve_for_launch(&launch_cwd))
             .await
             .map_err(|e| e.to_string())?;
-        let sign_in_message = spec.sign_in_message();
         self.stderr.lock().clear();
         self.config_sent.lock().clear();
         let weak = Arc::downgrade(self);
@@ -1439,7 +1497,9 @@ impl Task {
             .map_err(|e| format!("Couldn't start {} (`{}`): {e}", spec.name, spec.command))?;
 
         let init = peer.initialize(&client_info()).await.map_err(|e| self.describe(e))?;
+        let sign_in_message = spec.sign_in_message(&init.auth_methods);
         let can_load = init.load_session();
+        let mcp_stdio = init.mcp_stdio();
         let (capabilities, embedded) = capabilities_of(&init);
         // Agents that compare canonical paths fail in a symlinked directory (macOS `/tmp`).
         let cwd_s = dunce::canonicalize(&cwd).unwrap_or(cwd).to_string_lossy().into_owned();
@@ -1448,7 +1508,7 @@ impl Task {
         if let (Some(id), true) = (saved, can_load) {
             self.replaying.store(true, Ordering::Release);
             let loaded: Result<Value, RpcError> =
-                peer.request("session/load", json!({ "sessionId": id, "cwd": cwd_s, "mcpServers": [] }), None).await;
+                peer.request("session/load", json!({ "sessionId": id, "cwd": cwd_s, "mcpServers": mcp_servers_for(mcp_stdio, &self.shared.paths.project_root) }), None).await;
             tokio::time::sleep(REPLAY_GRACE).await;
             self.replaying.store(false, Ordering::Release);
             match loaded {
@@ -1461,14 +1521,13 @@ impl Task {
             Some(s) => s,
             None => {
                 let v: Value = peer
-                    .request("session/new", json!({ "cwd": cwd_s, "mcpServers": [] }), None)
+                    .request(
+                        "session/new",
+                        json!({ "cwd": cwd_s, "mcpServers": mcp_servers_for(mcp_stdio, &self.shared.paths.project_root) }),
+                        None,
+                    )
                     .await
-                    .map_err(|e| match e {
-                        RpcError::Server { ref message, .. } if message.to_lowercase().contains("auth") => {
-                            sign_in_message.clone()
-                        }
-                        e => self.describe(e),
-                    })?;
+                    .map_err(|e| self.sign_in_error(&e, Some(&sign_in_message)).unwrap_or_else(|| self.describe(e)))?;
                 let id = v.get("sessionId").and_then(Value::as_str).ok_or("the agent returned no session")?.to_owned();
                 (id, v)
             }
@@ -1557,7 +1616,8 @@ impl Task {
         }
         self.persist();
         self.emit_task();
-        let live = Live { sign_in_message, peer, session: session_id, capabilities, embedded, resumable: can_load };
+        let live =
+            Live { sign_in_message, peer, session: session_id, capabilities, embedded, resumable: can_load, mcp_stdio };
         *self.live.lock() = Some(live.clone());
         Ok(live)
     }
@@ -1581,6 +1641,7 @@ impl Task {
                 .collect()
         };
         if due.is_empty() {
+            self.approve_pending();
             return;
         }
         let task = self.clone();
@@ -1610,6 +1671,7 @@ impl Task {
                     Err(e) => tracing::warn!("agent task {}: setting {} to {value} failed: {e}", task.id, option.id),
                 }
             }
+            task.approve_pending();
             task.persist();
             task.emit_task();
         });
@@ -1699,7 +1761,7 @@ impl Task {
                     true
                 }
                 "available_commands_update" => {
-                    s.task.commands = config::commands_of(update);
+                    s.task.commands = config::commands_of(update, &provider);
                     true
                 }
                 "usage_update" => {
@@ -1726,6 +1788,9 @@ impl Task {
             if kind == "config_option_update" && !self.replaying.load(Ordering::Acquire) {
                 self.apply_late_choices();
             }
+            if !self.replaying.load(Ordering::Acquire) && kind == "current_mode_update" {
+                self.approve_pending();
+            }
             return;
         }
         if self.replaying.load(Ordering::Acquire) {
@@ -1857,7 +1922,7 @@ impl Task {
 
     fn approve_pending(&self) {
         let s = self.state.lock();
-        if self.cancel_pending.load(Ordering::Acquire) || !config::bypass_approvals(&s.task.provider, &s.task.config) {
+        if self.cancel_pending.load(Ordering::Acquire) || !config::bypass_approvals(&s.task.config) {
             return;
         }
         let mut pending = self.permissions.lock();
@@ -2206,3 +2271,20 @@ mod replay;
 mod replay_tests;
 #[cfg(test)]
 mod tests;
+
+// The desktop advertises its relay only while the built-in server is listening.
+static MCP_EXECUTABLE: parking_lot::RwLock<Option<std::path::PathBuf>> = parking_lot::RwLock::new(None);
+
+pub fn set_mcp_executable(executable: Option<std::path::PathBuf>) {
+    *MCP_EXECUTABLE.write() = executable;
+}
+
+fn mcp_servers_for(supported: bool, root: &std::path::Path) -> Vec<Value> {
+    stdio_mcp_servers(MCP_EXECUTABLE.read().as_deref(), supported, root)
+}
+
+fn stdio_mcp_servers(executable: Option<&std::path::Path>, supported: bool, root: &std::path::Path) -> Vec<Value> {
+    let Some(executable) = executable.filter(|_| supported) else { return Vec::new() };
+    let command = ide_mcp::stdio_command(executable, root);
+    vec![json!({ "name": "OpenIDEA", "command": command[0], "args": command[1..], "env": [] })]
+}

crates/ide-agent/src/model.rs

@@ -156,6 +156,14 @@ pub struct AgentConfigOption {
     pub via: AgentConfigVia,
 }
 
+#[derive(Clone, Copy, Debug, Default, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub enum AgentCommandSource {
+    #[default]
+    Command,
+    Skill,
+}
+
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
 #[serde(rename_all = "camelCase")]
 pub struct AgentCommand {
@@ -164,6 +172,8 @@ pub struct AgentCommand {
     pub description: String,
     /// What to type after the command, when it takes input.
     pub hint: Option<String>,
+    #[serde(default)]
+    pub source: AgentCommandSource,
 }
 
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]

crates/ide-agent/src/native/claude/mod.rs

@@ -69,6 +69,38 @@ pub(crate) fn connect(
     Ok(super::serve(shim, client))
 }
 
+/// Discover commands without a prompt, ACP session, or pending session file.
+pub(crate) async fn commands(spec: ProviderSpec, cwd: PathBuf) -> Result<Vec<Value>, String> {
+    tokio::time::timeout(Duration::from_secs(5), async move {
+        let spec = tokio::task::spawn_blocking(move || (spec.resolve_for_launch(&cwd), cwd));
+        let (spec, cwd) = spec.await.map_err(|e| e.to_string())?;
+        let mut args = spec.args;
+        args.extend(Start::New { id: uuid::Uuid::new_v4().to_string() }.args());
+        let launch = Launch { program: spec.command, args, cwd, env: spec.env };
+        let mut io = cli::Process.launch(&launch, Arc::new(|_| {})).map_err(|e| e.to_string())?;
+        let _stop = io.kill.clone().drop_guard();
+        let request = json!({ "type": "control_request", "request_id": "commands",
+            "request": { "subtype": "initialize", "perTaskStopAffordance": true } });
+        io.stdin.write_all(format!("{request}\n").as_bytes()).await.map_err(|e| e.to_string())?;
+        io.stdin.flush().await.map_err(|e| e.to_string())?;
+        let mut lines = BufReader::new(io.stdout).lines();
+        while let Some(line) = lines.next_line().await.map_err(|e| e.to_string())? {
+            let Ok(msg) = serde_json::from_str::<Value>(&line) else { continue };
+            if msg["type"] == "control_response" && msg["response"]["request_id"] == "commands" {
+                let response = &msg["response"];
+                return if response["subtype"] == "success" {
+                    Ok(Settings::from_cli(&response["response"], &Value::Null).commands)
+                } else {
+                    Err("Claude Code did not initialize".into())
+                };
+            }
+        }
+        Err("Claude Code exited".into())
+    })
+    .await
+    .map_err(|_| "Claude Code command discovery timed out".to_owned())?
+}
+
 struct Config {
     pub program: String,
     /// Extra arguments (a custom agent's), before the session's own.
@@ -98,6 +130,7 @@ pub(super) struct Shim {
 struct Session {
     id: String,
     cwd: PathBuf,
+    mcp_config: Option<tempfile::TempPath>,
     shim: Weak<Shim>,
     st: Mutex<State>,
     /// Serializes (re)starting the process.
@@ -264,9 +297,24 @@ impl Shim {
         Ok(history::chain(&entries, at.as_deref()).into_iter().cloned().collect())
     }
 
-    fn add_session(self: &Arc<Self>, id: &str, cwd: PathBuf, start: Start, pending: bool) -> Arc<Session> {
+    fn add_session(
+        self: &Arc<Self>,
+        id: &str,
+        cwd: PathBuf,
+        start: Start,
+        pending: bool,
+        mcp_config: Option<String>,
+    ) -> Arc<Session> {
+        let mcp_config = mcp_config.and_then(|json| match write_mcp_config(&json) {
+            Ok(path) => Some(path),
+            Err(e) => {
+                tracing::warn!("Claude Code session {id}: cannot write its MCP configuration: {e}");
+                None
+            }
+        });
         let session = Arc::new(Session {
             id: id.to_owned(),
+            mcp_config,
             shim: Arc::downgrade(self),
             st: Mutex::new(State {
                 proc: None,
@@ -312,6 +360,7 @@ impl Shim {
                         "loadSession": true,
                         "promptCapabilities": { "image": true, "embeddedContext": true },
                         "sessionCapabilities": { "fork": {} },
+                        "mcpCapabilities": { "stdio": true, "http": true, "sse": true },
                         "_meta": { "openidea": { "rollback": true, "steer": true, "backgroundTasks": true } },
                     },
                     "agentInfo": { "name": "claude", "title": "Claude Code", "version": self.version() },
@@ -320,7 +369,13 @@ impl Shim {
             }
             "session/new" => {
                 let id = new_uuid(false);
-                let session = self.add_session(&id, self.cwd_of(&params), Start::New { id: id.clone() }, false);
+                let session = self.add_session(
+                    &id,
+                    self.cwd_of(&params),
+                    Start::New { id: id.clone() },
+                    false,
+                    mcp_config(&params),
+                );
                 rt.block_on(session.ensure()).map_err(|e| self.start_error(&session, e))?;
                 session.announce_commands();
                 Ok(json!({ "sessionId": id, "configOptions": session.st.lock().settings.options() }))
@@ -336,7 +391,7 @@ impl Shim {
                     None => return Err(invalid(format!("no Claude Code session {id} in {}", cwd.display()))),
                 };
                 let chain = self.base_chain(&cwd, &start).map_err(internal)?;
-                let session = self.add_session(id, cwd, start, pending);
+                let session = self.add_session(id, cwd, start, pending, mcp_config(&params));
                 rt.block_on(session.ensure()).map_err(|e| self.start_error(&session, e))?;
                 if method == "session/load" {
                     session.replay(&chain);
@@ -362,7 +417,7 @@ impl Shim {
                     (start, st.settings.clone())
                 };
                 self.save_pending(&id, Some(&start));
-                let session = self.add_session(&id, source.cwd.clone(), start, true);
+                let session = self.add_session(&id, source.cwd.clone(), start, true, mcp_config(&params));
                 session.st.lock().settings = settings;
                 let options = session.st.lock().settings.options();
                 Ok(json!({ "sessionId": id, "configOptions": options }))
@@ -556,6 +611,9 @@ impl Session {
             old.end();
         }
         let mut args = shim.config.args.clone();
+        if let Some(config) = &self.mcp_config {
+            args.extend(["--mcp-config".to_owned(), config.to_string_lossy().into_owned()]);
+        }
         args.extend(start.args());
         let launch =
             Launch { program: shim.config.program.clone(), args, cwd: self.cwd.clone(), env: shim.config.env.clone() };
@@ -1345,3 +1403,38 @@ fn start_from_json(v: &Value) -> Option<Start> {
     }
     Some(Start::Fork { from: s("fork")?, id: s("id")?, at: s("at") })
 }
+
+/// Writes `json` to a new file only this user can read (removed when the path is dropped).
+fn write_mcp_config(json: &str) -> std::io::Result<tempfile::TempPath> {
+    let mut file = tempfile::Builder::new().prefix("openidea-mcp-").suffix(".json").tempfile()?;
+    std::io::Write::write_all(&mut file, json.as_bytes())?;
+    Ok(file.into_temp_path())
+}
+
+/// ACP `mcpServers` as Claude Code's `--mcp-config` JSON (`None` when there are none).
+fn mcp_config(params: &Value) -> Option<String> {
+    let servers = params.get("mcpServers")?.as_array()?;
+    let pairs = |v: Option<&Value>| -> serde_json::Map<String, Value> {
+        v.and_then(Value::as_array)
+            .into_iter()
+            .flatten()
+            .filter_map(|p| Some((p.get("name")?.as_str()?.to_owned(), p.get("value")?.clone())))
+            .collect()
+    };
+    let mut out = serde_json::Map::new();
+    for server in servers {
+        let Some(name) = server.get("name").and_then(Value::as_str) else { continue };
+        let entry = match server.get("type").and_then(Value::as_str) {
+            Some(kind @ ("http" | "sse")) => {
+                json!({ "type": kind, "url": server.get("url"), "headers": pairs(server.get("headers")) })
+            }
+            _ => json!({
+                "command": server.get("command"),
+                "args": server.get("args").cloned().unwrap_or_else(|| json!([])),
+                "env": pairs(server.get("env")),
+            }),
+        };
+        out.insert(name.to_owned(), entry);
+    }
+    (!out.is_empty()).then(|| json!({ "mcpServers": out }).to_string())
+}

crates/ide-agent/src/native/claude/tests.rs

@@ -1170,3 +1170,29 @@ async fn skipped_questions_have_no_answers() {
     let cancelled = ask_questions(&input, &json!({}), |_, _| async { None }).await;
     assert_eq!(cancelled, None);
 }
+
+#[test]
+fn mcp_servers_become_an_mcp_config() {
+    assert_eq!(mcp_config(&json!({ "mcpServers": [] })), None);
+    assert_eq!(mcp_config(&json!({})), None);
+    let config = mcp_config(&json!({ "mcpServers": [
+        { "type": "http", "name": "openidea", "url": "http://127.0.0.1:1/mcp",
+          "headers": [{ "name": "Authorization", "value": "Bearer t" }] },
+        { "name": "local", "command": "srv", "args": ["-x"], "env": [{ "name": "K", "value": "V" }] },
+    ] }))
+    .unwrap();
+    let v: Value = serde_json::from_str(&config).unwrap();
+    assert_eq!(
+        v["mcpServers"]["openidea"],
+        json!({ "type": "http", "url": "http://127.0.0.1:1/mcp", "headers": { "Authorization": "Bearer t" } })
+    );
+    assert_eq!(v["mcpServers"]["local"], json!({ "command": "srv", "args": ["-x"], "env": { "K": "V" } }));
+
+    let path = write_mcp_config(&config).unwrap();
+    assert_eq!(std::fs::read_to_string(&path).unwrap(), config);
+    #[cfg(unix)]
+    assert_eq!(std::os::unix::fs::PermissionsExt::mode(&std::fs::metadata(&path).unwrap().permissions()) & 0o077, 0);
+    let kept = path.to_path_buf();
+    drop(path);
+    assert!(!kept.exists());
+}

crates/ide-agent/src/native/codex/mod.rs

@@ -8,6 +8,7 @@ mod translate;
 mod tests;
 
 use super::Shim;
+use crate::acp::AUTH_REQUIRED;
 use crate::provider::ProviderSpec;
 use ide_jsonrpc::{Framing, Handler, Peer, RpcError, codes};
 use parking_lot::Mutex;
@@ -27,8 +28,6 @@ const OUTPUT_EVERY: Duration = Duration::from_millis(200);
 const EARLY_CANCEL: Duration = Duration::from_secs(1);
 /// How long the client's connection outlives codex.
 const EXIT_GRACE: Duration = Duration::from_millis(100);
-/// ACP's error code for a request that needs the user to sign in.
-const AUTH_REQUIRED: i64 = -32000;
 
 pub(crate) fn connect(
     spec: &ProviderSpec,
@@ -204,7 +203,7 @@ fn from_codex(e: RpcError) -> ResponseError {
                 code,
                 codes::PARSE_ERROR | codes::INVALID_REQUEST | codes::METHOD_NOT_FOUND | codes::INVALID_PARAMS
             );
-            let code = if !protocol && message.to_lowercase().contains("auth") { AUTH_REQUIRED } else { code };
+            let code = if !protocol && crate::acp::auth_required(code, &message) { AUTH_REQUIRED } else { code };
             ResponseError { code, message, data }
         }
         RpcError::Closed => error(codes::INTERNAL_ERROR, "Codex exited"),
@@ -264,7 +263,7 @@ impl CodexShim {
             "agentCapabilities": {
                 "loadSession": true,
                 "promptCapabilities": { "image": true, "audio": false, "embeddedContext": true },
-                "mcpCapabilities": { "http": false, "sse": false },
+                "mcpCapabilities": { "http": false, "sse": false, "stdio": true },
                 "sessionCapabilities": { "fork": {}, "close": {} },
                 "_meta": { "openidea": { "rollback": true, "steer": true } },
             },
@@ -318,7 +317,11 @@ impl CodexShim {
 
     async fn new_session(&self, params: &Value) -> Result<Value, ResponseError> {
         let models = self.models().await;
-        let result = self.call("thread/start", json!({ "cwd": params.get("cwd") })).await?;
+        let mut request = json!({ "cwd": params.get("cwd") });
+        if let Some(config) = translate::mcp_config(params) {
+            request["config"] = config;
+        }
+        let result = self.call("thread/start", request).await?;
         let (id, options) = self.open_thread(&result, &models, None);
         if id.is_empty() {
             return Err(error(codes::INTERNAL_ERROR, "codex started no thread"));
@@ -330,7 +333,11 @@ impl CodexShim {
     async fn load_session(&self, params: &Value) -> Result<Value, ResponseError> {
         let id = str_param(params, "sessionId")?;
         let models = self.models().await;
-        let result = self.call("thread/resume", json!({ "threadId": id, "cwd": params.get("cwd") })).await?;
+        let mut request = json!({ "threadId": id, "cwd": params.get("cwd") });
+        if let Some(config) = translate::mcp_config(params) {
+            request["config"] = config;
+        }
+        let result = self.call("thread/resume", request).await?;
         let (_, options) = self.open_thread(&result, &models, None);
         let cwd = self.state.lock().threads.get(id).and_then(|t| t.cwd.clone());
         let thread = result.get("thread").unwrap_or(&Value::Null);
@@ -345,6 +352,9 @@ impl CodexShim {
         let models = self.models().await;
         let settings = self.state.lock().threads.get(source).and_then(|t| t.settings.clone());
         let mut request = json!({ "threadId": source, "cwd": params.get("cwd") });
+        if let Some(config) = translate::mcp_config(params) {
+            request["config"] = config;
+        }
         if let Some(s) = &settings {
             request["model"] = json!(s.model_slug(&models));
             request["approvalPolicy"] = json!(s.mode.approval_policy());

crates/ide-agent/src/native/codex/tests.rs

@@ -623,6 +623,23 @@ async fn auth_failure_names_auth() {
     assert!(start.get("jsonrpc").is_some(), "codex accepts the jsonrpc field");
 }
 
+#[test]
+fn request_errors_classify_authentication_without_matching_author_or_protocol_errors() {
+    for (code, message, expected) in [
+        (codes::INTERNAL_ERROR, "Missing author field", codes::INTERNAL_ERROR),
+        (codes::INTERNAL_ERROR, "Unknown authority", codes::INTERNAL_ERROR),
+        (codes::INTERNAL_ERROR, "Authentication failed: expired token", AUTH_REQUIRED),
+        (codes::INTERNAL_ERROR, "Unauthorized", AUTH_REQUIRED),
+        (codes::METHOD_NOT_FOUND, "authentication method not found", codes::METHOD_NOT_FOUND),
+        (AUTH_REQUIRED, "Account is not eligible", AUTH_REQUIRED),
+    ] {
+        let response = from_codex(RpcError::Server { code, message: message.into(), data: Some(json!({"detail": 1})) });
+        assert_eq!(response.code, expected, "{message}");
+        assert_eq!(response.message, message);
+        assert_eq!(response.data, Some(json!({"detail": 1})));
+    }
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn a_stop_sent_right_after_the_prompt_interrupts_the_turn() {
     let (results, _client, frames, _) = replay(Scenario::Interrupt).await;
@@ -1027,3 +1044,15 @@ fn v_method(line: &str) -> Option<&str> {
     let at = line.find("\"method\":\"")? + 10;
     line[at..].split('"').next()
 }
+
+#[test]
+fn session_mcp_servers_become_thread_configuration() {
+    assert!(mcp_config(&json!({"mcpServers":[]})).is_none());
+    assert_eq!(
+        mcp_config(&json!({"mcpServers":[{"name":"OpenIDEA","command":"/app/openidea",
+        "args":["--mcp-stdio","--project","/project"],"env":[{"name":"K","value":"V"}]}]})),
+        Some(
+            json!({"mcp_servers":{"OpenIDEA":{"command":"/app/openidea","args":["--mcp-stdio","--project","/project"],"env":{"K":"V"}}}})
+        )
+    );
+}

crates/ide-agent/src/native/codex/translate.rs

@@ -836,3 +836,31 @@ pub(super) fn tail(text: &str) -> String {
 fn str_of(v: &Value, key: &str) -> Option<String> {
     v.get(key).and_then(Value::as_str).map(str::to_owned)
 }
+
+/// Session-scoped MCP configuration, carried in thread/start, resume and fork.
+pub(super) fn mcp_config(params: &Value) -> Option<Value> {
+    let mut servers = serde_json::Map::new();
+    for server in params.get("mcpServers")?.as_array()? {
+        if server.get("type").and_then(Value::as_str).is_some_and(|t| t != "stdio") {
+            continue;
+        }
+        let (Some(name), Some(command)) =
+            (server.get("name").and_then(Value::as_str), server.get("command").and_then(Value::as_str))
+        else {
+            continue;
+        };
+        let env: serde_json::Map<String, Value> = server
+            .get("env")
+            .and_then(Value::as_array)
+            .into_iter()
+            .flatten()
+            .filter_map(|v| Some((v.get("name")?.as_str()?.to_owned(), v.get("value")?.clone())))
+            .collect();
+        servers.insert(
+            name.into(),
+            json!({"command":command,
+            "args":server.get("args").cloned().unwrap_or_else(||json!([])),"env":env}),
+        );
+    }
+    (!servers.is_empty()).then(|| json!({"mcp_servers":servers}))
+}

crates/ide-agent/src/provider.rs

@@ -5,6 +5,7 @@
 use crate::{AgentCommandReadOnlyReason, AgentProvider, AgentSource};
 use ide_core::{IdeError, IdeResult};
 use serde::{Deserialize, Serialize};
+use serde_json::Value;
 use std::collections::BTreeMap;
 use std::path::{Path, PathBuf};
 
@@ -92,9 +93,26 @@ impl ProviderSpec {
         render_login_hint(self, program, on_path.as_deref(), cfg!(windows))
     }
 
-    pub(crate) fn sign_in_message(&self) -> String {
+    pub(crate) fn sign_in_message(&self, auth_methods: &[Value]) -> String {
         let name = &self.name;
-        let hint = self.login_hint(Path::new(&self.command));
+        let program = Path::new(&self.command);
+        let terminal_args = matches!(self.source, AgentSource::Registry { .. })
+            .then(|| {
+                auth_methods.iter().find_map(|method| {
+                    if method.get("type").and_then(Value::as_str) != Some("terminal") {
+                        return None;
+                    }
+                    method.get("args")?.as_array()?.iter().map(Value::as_str).collect::<Option<Vec<_>>>()
+                })
+            })
+            .flatten();
+        let hint = match terminal_args {
+            Some(args) => {
+                let command = render_login_command(program, args, cfg!(windows));
+                format!("Run `{command}` in a terminal.")
+            }
+            None => self.login_hint(program),
+        };
         format!("{name} needs you to sign in. {hint}")
     }
 
@@ -124,14 +142,8 @@ fn render_login_hint(spec: &ProviderSpec, program: &Path, on_path: Option<&Path>
     if on_path.is_some_and(|path| same_path(path, program)) {
         return spec.login_hint.clone();
     }
-    let path = program.to_string_lossy();
-    let quoted = if windows {
-        format!("& '{}'", path.replace('\'', "''"))
-    } else {
-        format!("'{}'", path.replace('\'', "'\\''"))
-    };
     let (args, suffix) = rest.split_once('`').expect("built-in login hints delimit their command");
-    let command = format!("{quoted}{args}");
+    let command = render_login_command(program, args.split_whitespace(), windows);
     match suffix {
         " in a terminal." => format!("Run `{command}` in a terminal."),
         " in a terminal and sign in." => format!("Run `{command}` in a terminal and sign in."),
@@ -139,6 +151,22 @@ fn render_login_hint(spec: &ProviderSpec, program: &Path, on_path: Option<&Path>
     }
 }
 
+fn render_login_command<'a>(program: &Path, args: impl IntoIterator<Item = &'a str>, windows: bool) -> String {
+    let quote = |word: &str| {
+        if windows { format!("'{}'", word.replace('\'', "''")) } else { format!("'{}'", word.replace('\'', "'\\''")) }
+    };
+    let mut command = format!("{}{}", if windows { "& " } else { "" }, quote(&program.to_string_lossy()));
+    for arg in args {
+        command.push(' ');
+        if !arg.is_empty() && arg.chars().all(|c| c.is_ascii_alphanumeric() || "-_=./".contains(c)) {
+            command.push_str(arg);
+        } else {
+            command.push_str(&quote(arg));
+        }
+    }
+    command
+}
+
 /// Whether `id` names a built-in agent that needs no registry install (native drivers
 /// and `npx -y` adapters). CLI built-ins (`copilot`, `gemini`, …) can be installed and
 /// updated from the ACP Registry into `<config>/agents/<id>.toml`.
@@ -370,6 +398,7 @@ fn is_executable(p: &Path) -> bool {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use serde_json::json;
 
     #[test]
     fn login_hints_cover_all_builtin_commands_and_preserve_separate_login_tools() {
@@ -429,12 +458,43 @@ mod tests {
         cursor.env.push(("PATH".into(), dir.path().to_string_lossy().into_owned()));
         let resolved = cursor.clone().resolve_for_launch(dir.path());
         assert_eq!(Path::new(&resolved.command), program);
-        assert!(resolved.sign_in_message().contains(&*program.to_string_lossy()));
+        assert!(resolved.sign_in_message(&[]).contains(&*program.to_string_lossy()));
         cursor.command = format!("tools/{command}");
         let resolved = cursor.resolve_for_launch(dir.path());
         assert_eq!(Path::new(&resolved.command), dir.path().join("tools").join(command));
     }
 
+    #[test]
+    fn terminal_login_commands_quote_the_binary_and_each_argument() {
+        for (windows, expected) in [
+            (false, "'/agent'\\''s tools/$cli' auth login --account 'user name' 'a'\\''b' '$token' ''"),
+            (true, "& '/agent''s tools/$cli' auth login --account 'user name' 'a''b' '$token' ''"),
+        ] {
+            assert_eq!(
+                render_login_command(
+                    Path::new("/agent's tools/$cli"),
+                    ["auth", "login", "--account", "user name", "a'b", "$token", ""],
+                    windows
+                ),
+                expected
+            );
+        }
+        let mut spec = builtin_spec("cursor").unwrap();
+        spec.id = "custom".into();
+        spec.source = AgentSource::Registry { version: "1.4.5".into(), update: None };
+        spec.login_hint = "Sign in with the agent's own command line first.".into();
+        for method in [
+            json!({"type": "terminal"}),
+            json!({"type": "terminal", "args": ["login", null]}),
+            json!({"type": "agent", "args": ["login"]}),
+        ] {
+            assert_eq!(
+                spec.sign_in_message(&[method]),
+                "Cursor needs you to sign in. Sign in with the agent's own command line first."
+            );
+        }
+    }
+
     #[cfg(unix)]
     #[test]
     fn registry_login_hint_names_the_installed_executable() {

crates/ide-agent/src/skills.rs

@@ -2,7 +2,7 @@
 //! skills (`.claude/skills/<dir>/SKILL.md`) and custom commands (`.claude/commands/**/*.md`)
 //! of the working directory and every directory above it, then the user's `~/.claude`.
 
-use crate::AgentCommand;
+use crate::{AgentCommand, AgentCommandSource};
 use std::collections::HashSet;
 use std::path::Path;
 
@@ -36,9 +36,14 @@ pub(crate) fn discover(cwd: &Path, home: Option<&Path>) -> Vec<AgentCommand> {
 
 /// `first` (the agent's own list) plus the commands of `more` it lacks.
 pub(crate) fn merge(first: Vec<AgentCommand>, more: Vec<AgentCommand>) -> Vec<AgentCommand> {
-    let names: HashSet<String> = first.iter().map(|c| c.name.clone()).collect();
     let mut out = first;
-    out.extend(more.into_iter().filter(|c| !names.contains(&c.name)));
+    for c in more {
+        if let Some(offered) = out.iter_mut().find(|offered| offered.name == c.name) {
+            offered.source = c.source;
+        } else {
+            out.push(c);
+        }
+    }
     out
 }
 
@@ -61,7 +66,7 @@ fn skills(dir: &Path) -> Vec<AgentCommand> {
                 return None;
             }
             let name = meta.get("name").filter(|n| !n.is_empty()).map(str::to_owned).or_else(|| file_name(&path))?;
-            Some(meta.command(name, &text))
+            Some(meta.command(name, &text, AgentCommandSource::Skill))
         })
         .collect();
     out.sort_by(|a, b| a.name.cmp(&b.name));
@@ -79,7 +84,7 @@ fn commands(dir: &Path, prefix: &str, depth: usize, out: &mut Vec<AgentCommand>)
         } else if let Some(stem) = name.strip_suffix(".md")
             && let Ok(text) = std::fs::read_to_string(&path)
         {
-            out.push(Frontmatter::parse(&text).command(format!("{prefix}{stem}"), &text));
+            out.push(Frontmatter::parse(&text).command(format!("{prefix}{stem}"), &text, AgentCommandSource::Command));
         }
     }
 }
@@ -147,7 +152,7 @@ impl Frontmatter {
     }
 
     /// `description`, else the body's first line.
-    fn command(&self, name: String, text: &str) -> AgentCommand {
+    fn command(&self, name: String, text: &str, source: AgentCommandSource) -> AgentCommand {
         let description = self.get("description").filter(|d| !d.is_empty()).map(str::to_owned).unwrap_or_else(|| {
             let body = text.get(self.body..).unwrap_or_default();
             body.lines()
@@ -158,6 +163,7 @@ impl Frontmatter {
         });
         AgentCommand {
             name,
+            source,
             description: truncate(&description),
             hint: self.get("argument-hint").filter(|h| !h.is_empty()).map(str::to_owned),
         }
@@ -194,13 +200,20 @@ mod tests {
     }
 
     fn cmd(name: &str, description: &str) -> AgentCommand {
-        AgentCommand { name: name.into(), description: description.into(), hint: None }
+        AgentCommand {
+            name: name.into(),
+            description: description.into(),
+            hint: None,
+            source: AgentCommandSource::Command,
+        }
     }
 
     #[test]
     fn project_and_user_skills_and_commands() {
         let tmp = tempfile::tempdir().unwrap();
-        let home = tmp.path().join("home");
+        // Home is an ancestor of the project, so the walk stops there instead of climbing
+        // past it into the real profile (a temp dir under the user's home holds its skills).
+        let home = tmp.path().to_path_buf();
         let repo = tmp.path().join("work").join("idea");
         let skills = repo.join(".claude/skills");
         write(
@@ -227,6 +240,12 @@ mod tests {
             ["issue-fix", "triage", "verify", "git:commit", "review", "parent", "lint", "brooks-review"]
         );
         let by = |n: &str| found.iter().find(|c| c.name == n).unwrap();
+        for name in ["issue-fix", "triage", "verify", "lint"] {
+            assert_eq!(by(name).source, AgentCommandSource::Skill);
+        }
+        for name in ["git:commit", "review", "parent", "brooks-review"] {
+            assert_eq!(by(name).source, AgentCommandSource::Command);
+        }
         assert_eq!(by("triage").description, "One pass over open issues and PRs");
         assert_eq!(by("issue-fix").description, "Fix an issue");
         assert_eq!(by("verify").description, "Build and drive the app");
@@ -262,10 +281,14 @@ mod tests {
     fn the_agents_entries_win() {
         let merged = merge(
             vec![cmd("triage", "from the agent"), cmd("compact", "Compact")],
-            vec![cmd("triage", "from disk"), cmd("verify", "Verify")],
+            vec![
+                AgentCommand { source: AgentCommandSource::Skill, ..cmd("triage", "from disk") },
+                cmd("verify", "Verify"),
+            ],
         );
         assert_eq!(names(&merged), ["triage", "compact", "verify"]);
         assert_eq!(merged[0].description, "from the agent");
+        assert_eq!(merged[0].source, AgentCommandSource::Skill);
     }
 
     #[test]

crates/ide-agent/src/tests.rs

@@ -35,6 +35,10 @@ struct FakeAgent {
     /// Without `loadSession` (a session lives only as long as its process).
     no_load: bool,
     auth_on_new: bool,
+    request_error: Option<(i64, String)>,
+    auth_methods: Vec<Value>,
+    /// Hold the late mode reply until the prompt's permission request is already waiting.
+    hold_late_mode: bool,
     empty_config: AtomicBool,
     /// Config options `session/new` reports after the model one (per-model efforts, say).
     extra_options: Mutex<Vec<Value>>,
@@ -126,7 +130,17 @@ impl Handler for FakeAgent {
         if (method == "session/new" && self.auth_on_new)
             || (method == "session/prompt" && params.pointer("/prompt/0/text") == Some(&json!("auth")))
         {
-            return Err((codes::INTERNAL_ERROR, "Authentication required".into()));
+            return Err(self
+                .request_error
+                .clone()
+                .unwrap_or((codes::INTERNAL_ERROR, "Authentication required".into())));
+        }
+        if self.hold_late_mode
+            && method == "session/set_config_option"
+            && params.get("value").and_then(Value::as_str) == Some("full-access")
+        {
+            // Let the prompt's permission request reach the task before the mode changes.
+            std::thread::sleep(Duration::from_millis(100));
         }
         let session = params.get("sessionId").and_then(Value::as_str).unwrap_or("s1").to_owned();
         match method {
@@ -134,8 +148,10 @@ impl Handler for FakeAgent {
                 if params.pointer("/clientCapabilities/subagents").is_some_and(Value::is_object) {
                     self.calls.lock().push("subagents".into());
                 }
-                Ok(json!({"protocolVersion": 1, "agentCapabilities": {"loadSession": !self.no_load,
-                    "sessionCapabilities": {"fork": {}}, "_meta": {"openidea": {"rollback": true, "steer": true, "backgroundTasks": true}}}}))
+                Ok(
+                    json!({"protocolVersion": 1, "authMethods": self.auth_methods, "agentCapabilities": {"loadSession": !self.no_load,
+                    "sessionCapabilities": {"fork": {}}, "_meta": {"openidea": {"rollback": true, "steer": true, "backgroundTasks": true}}}}),
+                )
             }
             "session/new" => {
                 if self.empty_config.load(Ordering::Acquire) {
@@ -200,6 +216,29 @@ impl Handler for FakeAgent {
                     self.say(&session, "ok");
                     return Ok(json!({"stopReason": "end_turn"}));
                 }
+                if text == "late full access" {
+                    // The mode option appears only now; the user's choice is applied late.
+                    self.update(
+                        &session,
+                        json!({"sessionUpdate": "config_option_update", "configOptions": [
+                            {"id": "mode", "category": "mode", "type": "select", "currentValue": "ask",
+                             "options": [{"value": "ask", "name": "Ask"}, {"value": "full-access", "name": "Full Access"}]}
+                        ]}),
+                    );
+                    let peer = self.latest();
+                    let answer: Value = tokio::runtime::Handle::current()
+                        .block_on(peer.request(
+                            "session/request_permission",
+                            json!({"sessionId": session, "toolCall": {"toolCallId": "late", "title": "Run cargo test"},
+                                "options": [{"optionId": "yes", "name": "Allow", "kind": "allow_once"},
+                                            {"optionId": "no", "name": "Reject", "kind": "reject_once"}]}),
+                            None,
+                        ))
+                        .unwrap();
+                    let chosen = answer.pointer("/outcome/optionId").and_then(Value::as_str).unwrap_or("none");
+                    self.say(&session, &format!("late chose {chosen}"));
+                    return Ok(json!({"stopReason": "end_turn"}));
+                }
                 if text == "ask" {
                     let peer = self.latest();
                     let answer: Value = tokio::runtime::Handle::current()
@@ -300,6 +339,9 @@ fn manager(dir: &Path, agent: Arc<FakeAgent>) -> AgentManager {
 }
 
 fn manager_at(dir: &Path, models_file: &Path, agent: Arc<FakeAgent>) -> AgentManager {
+    // These tests speak to FakeAgent, never an installed CLI, including after a provider reload.
+    let agents = dir.join("agents");
+    provider::set_builtin_command(&agents, "claude", Some(&dir.join("missing-claude").to_string_lossy())).unwrap();
     let connector: Connector = Arc::new(move |_spec, _cwd, client, _stderr| {
         let (a, b) = duplex(1 << 20);
         let (ar, aw) = tokio::io::split(a);
@@ -314,14 +356,97 @@ fn manager_at(dir: &Path, models_file: &Path, agent: Arc<FakeAgent>) -> AgentMan
             store_dir: dir.join("store"),
             worktrees_dir: dir.join("worktrees"),
             models_file: models_file.to_path_buf(),
-            custom_agents_dir: None,
-            home_dir: None,
+            custom_agents_dir: Some(agents),
+            // The project is the boundary of the skill walk: nothing above it (such as the
+            // user's profile, when temp lives under it) leaks into the test.
+            home_dir: Some(dir.to_path_buf()),
         },
         tokio::runtime::Handle::current(),
         connector,
     )
 }
 
+#[cfg(unix)]
+#[tokio::test(flavor = "multi_thread")]
+async fn claude_commands_before_session_are_fetched_once_and_saved() {
+    use std::os::unix::fs::PermissionsExt;
+
+    for outcome in ["success", "error", "exit", "timeout", "missing"] {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        let script = root.join("fake-claude");
+        std::fs::write(
+            &script,
+            r#"#!/usr/bin/env python3
+import json, os, pathlib, sys, time
+root = pathlib.Path.cwd()
+with (root / 'launches').open('a') as f:
+    f.write(json.dumps(sys.argv[1:]) + '\n')
+request = json.loads(sys.stdin.readline())
+with (root / 'requests').open('a') as f:
+    f.write(json.dumps(request) + '\n')
+outcome = os.environ['OUTCOME']
+if outcome == 'exit':
+    sys.exit(1)
+if outcome == 'timeout':
+    time.sleep(60)
+response = {'subtype': outcome, 'request_id': request['request_id']}
+if outcome == 'success':
+    response['response'] = {'commands': [
+        {'name': 'compact', 'description': 'Free up context', 'argumentHint': '[instructions]'},
+        {'name': 'clear'}, {'name': 'model'}, {'name': 'context'}]}
+else:
+    response['error'] = 'Authentication required'
+print(json.dumps({'type': 'control_response', 'response': response}), flush=True)
+for line in sys.stdin:
+    with (root / 'requests').open('a') as f:
+        f.write(line)
+"#,
+        )
+        .unwrap();
+        std::fs::set_permissions(&script, std::fs::Permissions::from_mode(0o755)).unwrap();
+        std::fs::create_dir_all(root.join(".claude/skills/triage")).unwrap();
+        std::fs::write(root.join(".claude/skills/triage/SKILL.md"), "---\nname: triage\ndescription: Triage\n---\n")
+            .unwrap();
+        let mgr = manager(root, Arc::new(FakeAgent::default()));
+        {
+            let mut providers = mgr.shared.providers.write();
+            let spec = providers.iter_mut().find(|p| p.id == "claude").unwrap();
+            if outcome != "missing" {
+                spec.command = script.to_string_lossy().into_owned();
+            }
+            spec.env = vec![("OUTCOME".into(), outcome.into())];
+        }
+        let (first, concurrent) = tokio::join!(mgr.commands("claude", None), mgr.commands("claude", None));
+        let first = first.unwrap();
+        assert_eq!(first, concurrent.unwrap());
+        assert_eq!(first, mgr.commands("claude", None).await.unwrap());
+        let names: Vec<_> = first.iter().map(|c| c.name.as_str()).collect();
+        if outcome == "success" {
+            assert_eq!(names, ["compact", "clear", "model", "context", "triage"]);
+            assert_eq!(first[0].hint.as_deref(), Some("[instructions]"));
+            let restored = manager(root, Arc::new(FakeAgent::default()));
+            assert_eq!(first, restored.commands("claude", None).await.unwrap());
+        } else {
+            assert_eq!(names, ["triage"], "{outcome}");
+            assert!(!root.join("models.json").exists());
+        }
+        assert!(mgr.tasks.read().is_empty());
+        assert!(!root.join("store").exists());
+        if outcome != "missing" {
+            let launches = std::fs::read_to_string(root.join("launches")).unwrap();
+            assert_eq!(launches.lines().count(), 1, "{outcome}");
+            let args: Vec<String> = serde_json::from_str(launches.trim()).unwrap();
+            assert!(args.windows(2).any(|a| a == ["--input-format", "stream-json"]));
+            let requests = std::fs::read_to_string(root.join("requests")).unwrap();
+            assert_eq!(requests.lines().count(), 1, "only initialize, no prompt or other control request");
+            let request: Value = serde_json::from_str(requests.trim()).unwrap();
+            assert_eq!(request["type"], "control_request");
+            assert_eq!(request["request"]["subtype"], "initialize");
+        }
+    }
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn authentication_failures_name_the_session_executable_at_start_and_during_prompts() {
     for auth_on_new in [true, false] {
@@ -360,7 +485,110 @@ async fn authentication_failures_name_the_session_executable_at_start_and_during
             .expect("authentication error");
         assert!(error.starts_with("Cursor needs you to sign in. Run `"), "{error}");
         assert!(error.contains(&*program.to_string_lossy()), "{error}");
-        assert!(error.ends_with(" login` in a terminal."), "{error}");
+        assert!(error.ends_with(" login` in a terminal.\n\nAuthentication required"), "{error}");
+        mgr.shutdown();
+    }
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn sign_in_errors_preserve_details_and_leave_unrelated_errors_unchanged() {
+    for auth_on_new in [true, false] {
+        for (code, message, sign_in) in [
+            (-32000, "This Google account is not eligible for this agent.", true),
+            (codes::INTERNAL_ERROR, "Authentication failed: token expired for account alice.", true),
+            (codes::INTERNAL_ERROR, "UNAUTHORIZED: account refused", true),
+            (codes::INTERNAL_ERROR, "You are not logged in to this installation.", true),
+            (codes::INTERNAL_ERROR, "Please sign in with your work account.", true),
+            (codes::INTERNAL_ERROR, "Missing author field", false),
+            (codes::INTERNAL_ERROR, "Unknown authority in configuration", false),
+        ] {
+            let tmp = tempfile::tempdir().unwrap();
+            let agent =
+                Arc::new(FakeAgent { auth_on_new, request_error: Some((code, message.into())), ..Default::default() });
+            let mgr = manager(tmp.path(), agent);
+            let task = mgr
+                .create(NewAgentTask {
+                    project_root: None,
+                    prompt: text("again"),
+                    provider: "cursor".into(),
+                    config: vec![],
+                    isolation: Isolation::Local,
+                    base: None,
+                })
+                .await
+                .unwrap();
+            if !auth_on_new {
+                wait_for(&mgr, &task.id, AgentStatus::Ready).await;
+                mgr.prompt(&task.id, text("auth"), false).await.unwrap();
+            }
+            wait_for(&mgr, &task.id, AgentStatus::Failed).await;
+            let entries = mgr.entries(&task.id, None).unwrap();
+            let error = entries
+                .iter()
+                .find_map(|e| match e {
+                    AgentEntry::Error { message, .. } => Some(message),
+                    _ => None,
+                })
+                .unwrap();
+            if sign_in {
+                assert!(error.starts_with("Cursor needs you to sign in. Run `"), "{error}");
+                assert!(error.ends_with(&format!("\n\n{message}")), "{error}");
+            } else {
+                assert_eq!(error, message);
+            }
+            mgr.shutdown();
+        }
+    }
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn registry_sign_in_errors_use_the_advertised_terminal_login() {
+    for terminal in [true, false] {
+        let tmp = tempfile::tempdir().unwrap();
+        let agent = Arc::new(FakeAgent {
+            auth_on_new: true,
+            request_error: Some((-32000, "This account is not eligible.".into())),
+            auth_methods: vec![json!({"type": if terminal { "terminal" } else { "agent" },
+                "id": "cli", "name": "CLI", "args": ["auth", "login"]})],
+            ..Default::default()
+        });
+        let mgr = manager(tmp.path(), agent);
+        let program = tmp.path().join("Registry Tools").join("antigravity.cmd");
+        let mut spec = provider::builtin_spec("cursor").unwrap();
+        spec.id = "antigravity".into();
+        spec.name = "Google Antigravity".into();
+        spec.command = program.to_string_lossy().into_owned();
+        spec.source = AgentSource::Registry { version: "1.4.5".into(), update: None };
+        spec.login_hint = "Sign in with the agent's own command line first.".into();
+        mgr.shared.providers.write().push(spec);
+        let task = mgr
+            .create(NewAgentTask {
+                project_root: None,
+                prompt: text("again"),
+                provider: "antigravity".into(),
+                config: vec![],
+                isolation: Isolation::Local,
+                base: None,
+            })
+            .await
+            .unwrap();
+        wait_for(&mgr, &task.id, AgentStatus::Failed).await;
+        let entries = mgr.entries(&task.id, None).unwrap();
+        let error = entries
+            .iter()
+            .find_map(|e| match e {
+                AgentEntry::Error { message, .. } => Some(message),
+                _ => None,
+            })
+            .unwrap();
+        assert!(error.starts_with("Google Antigravity needs you to sign in. "), "{error}");
+        if terminal {
+            assert!(error.contains(&*program.to_string_lossy()), "{error}");
+            assert!(error.contains(" auth login` in a terminal."), "{error}");
+        } else {
+            assert!(error.contains("Sign in with the agent's own command line first."), "{error}");
+        }
+        assert!(error.ends_with("\n\nThis account is not eligible."), "{error}");
         mgr.shutdown();
     }
 }
@@ -433,6 +661,7 @@ async fn builtin_commands_only_fill_verified_gaps_and_preserve_advertised_metada
         name: "compact".into(),
         description: "Agent supplied description".into(),
         hint: Some("instructions".into()),
+        source: AgentCommandSource::Command,
     };
     mgr.task(&task.id).unwrap().state.lock().task.commands = vec![advertised.clone()];
     // The task's provider wins over the caller's provider; metadata is not replaced.
@@ -1438,12 +1667,12 @@ async fn cursor_approval_switch_resolves_pending_and_survives_restart() {
     mgr.prompt(&task.id, text("late option"), false).await.unwrap();
     wait_for(&mgr, &task.id, AgentStatus::Ready).await;
     let t = mgr.task(&task.id).unwrap();
-    assert!(config::bypass_approvals("cursor", &t.state.lock().task.config));
+    assert!(config::bypass_approvals(&t.state.lock().task.config));
     t.kill();
     mgr.prompt(&task.id, text("Fix again"), false).await.unwrap();
     wait_for(&mgr, &task.id, AgentStatus::Ready).await;
     assert!(!agent.calls.lock().iter().any(|c| c.contains("bypass")));
-    assert!(config::bypass_approvals("cursor", &mgr.shared.known_config("cursor")));
+    assert!(config::bypass_approvals(&mgr.shared.known_config("cursor")));
     mgr.set_config(&task.id, config::CURSOR_APPROVAL, "ask".into()).await.unwrap();
     mgr.prompt(&task.id, text("Fix once more"), false).await.unwrap();
     wait_for(&mgr, &task.id, AgentStatus::NeedsInput).await;
@@ -1534,6 +1763,133 @@ async fn cursor_approval_choice_applies_before_first_prompt() {
     mgr.shutdown();
 }
 
+#[tokio::test(flavor = "multi_thread")]
+async fn a_full_access_mode_approves_tool_requests() {
+    let tmp = tempfile::tempdir().unwrap();
+    let agent = Arc::new(FakeAgent::default());
+    *agent.extra_options.lock() = vec![json!({
+        "id": "mode", "category": "mode", "type": "select", "currentValue": "ask",
+        "options": [{"value": "ask", "name": "Ask"}, {"value": "full-access", "name": "Full Access"}]
+    })];
+    let mgr = manager(tmp.path(), agent.clone());
+    let task = mgr
+        .create(NewAgentTask {
+            project_root: None,
+            prompt: text("Fix"),
+            provider: "claude".into(),
+            config: vec![AgentConfigChoice { id: "mode".into(), value: "full-access".into() }],
+            isolation: Isolation::Local,
+            base: None,
+        })
+        .await
+        .unwrap();
+    wait_for(&mgr, &task.id, AgentStatus::Ready).await;
+    assert!(agent.calls.lock().iter().any(|c| c.ends_with("\"full-access\"")));
+    assert!(
+        mgr.entries(&task.id, None)
+            .unwrap()
+            .iter()
+            .any(|entry| matches!(entry, AgentEntry::Permission { chosen: Some(name), .. } if name == "Allow"))
+    );
+
+    // Choosing Full Access while the request is already waiting also approves it.
+    let waiting = mgr
+        .create(NewAgentTask {
+            project_root: None,
+            prompt: text("Fix"),
+            provider: "claude".into(),
+            config: Vec::new(),
+            isolation: Isolation::Local,
+            base: None,
+        })
+        .await
+        .unwrap();
+    wait_for(&mgr, &waiting.id, AgentStatus::NeedsInput).await;
+    mgr.set_config(&waiting.id, "mode", "full-access".into()).await.unwrap();
+    wait_for(&mgr, &waiting.id, AgentStatus::Ready).await;
+    assert!(
+        mgr.entries(&waiting.id, None)
+            .unwrap()
+            .iter()
+            .any(|entry| matches!(entry, AgentEntry::Permission { chosen: Some(name), .. } if name == "Allow"))
+    );
+    mgr.shutdown();
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn a_late_full_access_option_approves_a_pending_request() {
+    let tmp = tempfile::tempdir().unwrap();
+    let agent = Arc::new(FakeAgent { hold_late_mode: true, ..Default::default() });
+    let mgr = manager(tmp.path(), agent.clone());
+    let task = mgr
+        .create(NewAgentTask {
+            project_root: None,
+            prompt: text("late full access"),
+            provider: "claude".into(),
+            config: vec![AgentConfigChoice { id: "mode".into(), value: "full-access".into() }],
+            isolation: Isolation::Local,
+            base: None,
+        })
+        .await
+        .unwrap();
+    let deadline = std::time::Instant::now() + Duration::from_secs(10);
+    loop {
+        let task = mgr.task(&task.id).unwrap();
+        let (status, busy) = {
+            let s = task.state.lock();
+            (s.task.status, s.busy)
+        };
+        if status == AgentStatus::Ready && !busy {
+            break;
+        }
+        if std::time::Instant::now() > deadline {
+            let _ = mgr.cancel(&task.id, None);
+            mgr.shutdown();
+            panic!("late Full Access did not approve the pending request");
+        }
+        tokio::time::sleep(Duration::from_millis(10)).await;
+    }
+    assert!(agent.calls.lock().iter().any(|c| c.ends_with("\"full-access\"")));
+    assert!(
+        mgr.entries(&task.id, None)
+            .unwrap()
+            .iter()
+            .any(|entry| matches!(entry, AgentEntry::Permission { chosen: Some(name), .. } if name == "Allow"))
+    );
+    mgr.shutdown();
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn an_allow_all_permissions_option_approves_tool_requests() {
+    let tmp = tempfile::tempdir().unwrap();
+    let agent = Arc::new(FakeAgent::default());
+    *agent.extra_options.lock() = vec![json!({
+        "id": "allow_all", "name": "Allow All", "category": "permissions", "type": "select", "currentValue": "off",
+        "options": [{"value": "off", "name": "Ask"}, {"value": "on", "name": "Full Access"}]
+    })];
+    let mgr = manager(tmp.path(), agent.clone());
+    let task = mgr
+        .create(NewAgentTask {
+            project_root: None,
+            prompt: text("Fix"),
+            provider: "claude".into(),
+            config: vec![AgentConfigChoice { id: "allow_all".into(), value: "on".into() }],
+            isolation: Isolation::Local,
+            base: None,
+        })
+        .await
+        .unwrap();
+    wait_for(&mgr, &task.id, AgentStatus::Ready).await;
+    assert!(agent.calls.lock().iter().any(|c| c.ends_with("\"on\"")));
+    assert!(
+        mgr.entries(&task.id, None)
+            .unwrap()
+            .iter()
+            .any(|entry| matches!(entry, AgentEntry::Permission { chosen: Some(name), .. } if name == "Allow"))
+    );
+    mgr.shutdown();
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn archived_tasks_can_be_restored_and_continue_their_session() {
     let tmp = tempfile::tempdir().unwrap();
@@ -1585,6 +1941,7 @@ async fn task_project_root_controls_local_and_worktree_repositories() {
         String::from_utf8_lossy(&out.stdout).trim().to_owned()
     };
     git(&["init", "-q", "-b", "member-main"]);
+    git(&["config", "core.autocrlf", "false"]);
     std::fs::write(member.join("file.txt"), "original\n").unwrap();
     git(&["add", "."]);
     git(&["commit", "-qm", "initial"]);
@@ -1898,6 +2255,7 @@ async fn delete_running_agent(no_load: bool) {
         assert!(out.status.success(), "{}", String::from_utf8_lossy(&out.stderr));
     };
     git(&["init", "-q", "-b", "main"]);
+    git(&["config", "core.autocrlf", "false"]);
     std::fs::write(root.join("file.txt"), "original\n").unwrap();
     git(&["add", "."]);
     git(&["commit", "-qm", "initial"]);
@@ -1986,3 +2344,17 @@ async fn delete_running_agent(no_load: bool) {
     };
     assert!(!alive, "the agent (pid {pid}) is still running");
 }
+
+#[test]
+fn mcp_servers_follow_server_state_and_agent_capabilities() {
+    let root = std::path::Path::new("/project");
+    let exe = std::path::Path::new("/app/openidea");
+    assert!(super::stdio_mcp_servers(None, true, root).is_empty());
+    assert!(super::stdio_mcp_servers(Some(exe), false, root).is_empty());
+    let servers = super::stdio_mcp_servers(Some(exe), true, root);
+    assert_eq!(
+        servers,
+        vec![json!({"name":"OpenIDEA","command":"/app/openidea",
+        "args":["--mcp-stdio","--project","/project"],"env":[]})]
+    );
+}

crates/ide-build/src/lib.rs

@@ -76,7 +76,7 @@ pub fn load_linked(
     gradle_settings: &ide_core::settings::GradleSettings,
 ) -> BuildModel {
     let maven = maven::has_projects(root, settings).then(|| {
-        let profiles = sync::maven_profiles(cache_dir);
+        let profiles = settings.profiles(&sync::maven_profiles(cache_dir));
         let repo = maven_repo.or_else(maven::default_local_repo);
         let mut m = maven::load_with_linked(root, repo, &profiles, &settings.linked_projects);
         maven::UnlinkedProjects::from_model(&m, settings).filter(&mut m);
@@ -222,6 +222,30 @@ mod tests {
         assert!(gradle_external_roots(&root, &temp.path().join("cache"), &settings).is_empty());
     }
 
+    #[test]
+    fn settings_profiles_and_checkbox_choices_control_modules_before_sync() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        std::fs::create_dir(root.join("extra")).unwrap();
+        std::fs::write(root.join("extra/pom.xml"), "<project><artifactId>extra</artifactId></project>").unwrap();
+        std::fs::write(
+            root.join("pom.xml"),
+            r#"<project><artifactId>root</artifactId><packaging>pom</packaging>
+            <profiles><profile><id>extra</id><modules><module>extra</module></modules></profile></profiles></project>"#,
+        )
+        .unwrap();
+        let cache = root.join("cache");
+        let settings = ide_core::settings::MavenSettings { active_profiles: "extra".into(), ..Default::default() };
+        let modules = |settings: &ide_core::settings::MavenSettings| {
+            load_linked(root, &cache, None, settings, &Default::default()).maven.unwrap().projects[0].modules.clone()
+        };
+        assert!(modules(&Default::default()).is_empty());
+        assert_eq!(modules(&settings), ["extra/pom.xml"]);
+        assert_eq!(maven::load_linked(root, &settings).projects[0].modules, ["extra/pom.xml"]);
+        save_maven_profiles(&cache, &["!extra".into()]).unwrap();
+        assert!(modules(&settings).is_empty());
+    }
+
     #[test]
     fn detects_build_systems_and_build_files() {
         let tmp = tempfile::tempdir().unwrap();

crates/ide-build/src/maven.rs

@@ -1063,7 +1063,7 @@ pub fn load(root: &Path) -> MavenModel {
 
 /// [`load`] with the POMs `settings` link (Add Maven Projects).
 pub fn load_linked(root: &Path, settings: &ide_core::settings::MavenSettings) -> MavenModel {
-    load_with_linked(root, default_local_repo(), &[], &settings.linked_projects)
+    load_with_linked(root, default_local_repo(), &settings.profiles(&[]), &settings.linked_projects)
 }
 
 pub(crate) fn load_with_repo(root: &Path, local_repo: Option<PathBuf>) -> MavenModel {

crates/ide-build/src/sync.rs

@@ -304,7 +304,7 @@ pub fn sync_maven(
     let mut model = maven::load_with_linked(
         root,
         maven::default_local_repo(),
-        &options.profiles,
+        &options.maven_settings.profiles(&options.profiles),
         &options.maven_settings.linked_projects,
     );
     maven::UnlinkedProjects::from_model(&model, &options.maven_settings).filter(&mut model);

crates/ide-cli/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "ide-cli"
+description = "The `openidea` command: arguments, the request it sends a running app over a local socket, and installing it on PATH"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+serde.workspace = true
+serde_json.workspace = true
+dirs.workspace = true
+tracing.workspace = true
+
+[target.'cfg(windows)'.dependencies]
+tokio = { workspace = true, features = ["net"] }
+winreg = "0.56"
+windows-sys = { version = "0.61", features = ["Win32_Foundation", "Win32_Storage_FileSystem", "Win32_System_Console", "Win32_UI_WindowsAndMessaging"] }
+
+[dev-dependencies]
+tempfile.workspace = true

crates/ide-cli/src/args.rs

@@ -0,0 +1,234 @@
+//! Command-line arguments of `openidea`.
+
+use crate::Target;
+use std::path::Path;
+
+pub const USAGE: &str = "\
+Usage: openidea [options] [[--line <n>] [--column <n>] path[:line[:column]] ...]
+       openidea diff <left> <right>
+
+Opens folders as projects and files in the editor of the running OpenIDEA,
+starting it if needed. Without paths, brings OpenIDEA to the front.
+Lines and columns start at 1; --line and --column apply to the next path.
+
+Options:
+  --line <n>     Put the caret on line <n> of the next file
+  --column <n>   Put the caret in column <n> of that line
+  -h, --help     Show this help
+  -v, --version  Show the version
+";
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum Command {
+    Help,
+    Version,
+    Open(Vec<Target>),
+    Diff(Vec<Target>),
+}
+
+/// Parses `args` (without the program name); relative paths resolve against `cwd`.
+pub fn parse(args: &[String], cwd: &Path) -> Result<Command, String> {
+    parse_with(args, cwd, &|p| p.exists())
+}
+
+fn parse_with(args: &[String], cwd: &Path, exists: &dyn Fn(&Path) -> bool) -> Result<Command, String> {
+    if args.first().is_some_and(|arg| arg == "diff") {
+        return match parse_paths(&args[1..], cwd, exists)? {
+            Command::Open(targets) if targets.len() == 2 => Ok(Command::Diff(targets)),
+            Command::Help => Ok(Command::Help),
+            _ => Err("diff needs two files".into()),
+        };
+    }
+    parse_paths(args, cwd, exists)
+}
+
+fn parse_paths(args: &[String], cwd: &Path, exists: &dyn Fn(&Path) -> bool) -> Result<Command, String> {
+    let mut targets = Vec::new();
+    let mut options = true;
+    let (mut line, mut column) = (None, None);
+    let mut args = args.iter();
+    while let Some(arg) = args.next() {
+        let (flag, inline) = match arg.split_once('=') {
+            Some((flag, value)) if options && flag.starts_with("--") => (flag, Some(value.to_owned())),
+            _ => (arg.as_str(), None),
+        };
+        match flag {
+            "--" if options => options = false,
+            "-h" | "--help" if options => return Ok(Command::Help),
+            "-v" | "--version" if options => return Ok(Command::Version),
+            "--line" | "--column" if options => {
+                let value = inline.or_else(|| args.next().cloned()).ok_or(format!("{flag} needs a number"))?;
+                let n = position(&value).ok_or(format!("{flag}: not a number from 1: {value}"))?;
+                *if flag == "--line" { &mut line } else { &mut column } = Some(n);
+            }
+            a if options && a.starts_with('-') && a != "-" => return Err(format!("unknown option: {a}")),
+            _ => {
+                let mut target = target(arg, cwd, exists)?;
+                if line.is_some() || column.is_some() {
+                    target.line = line.take().or(target.line).or(Some(1));
+                    target.column = column.take();
+                }
+                targets.push(target);
+            }
+        }
+    }
+    if line.is_some() || column.is_some() {
+        return Err("--line and --column need a file after them".into());
+    }
+    Ok(Command::Open(targets))
+}
+
+/// `arg` as a path, else as `path:line[:column]` when `path` exists.
+fn target(arg: &str, cwd: &Path, exists: &dyn Fn(&Path) -> bool) -> Result<Target, String> {
+    let path = cwd.join(arg);
+    if exists(&path) {
+        return Ok(Target { path, line: None, column: None });
+    }
+    for (base, line, column) in split_position(arg) {
+        let path = cwd.join(base);
+        if exists(&path) {
+            return Ok(Target { path, line: Some(line), column });
+        }
+    }
+    Err(format!("{arg}: no such file or directory"))
+}
+
+/// The readings of `arg` as `path:line:column`, then as `path:line`.
+fn split_position(arg: &str) -> Vec<(&str, u32, Option<u32>)> {
+    let Some((rest, last)) = arg.rsplit_once(':') else { return Vec::new() };
+    let Some(last) = position(last) else { return Vec::new() };
+    let mut readings = Vec::new();
+    if let Some((base, line)) = rest.rsplit_once(':')
+        && let Some(line) = position(line)
+        && !base.is_empty()
+    {
+        readings.push((base, line, Some(last)));
+    }
+    if !rest.is_empty() {
+        readings.push((rest, last, None));
+    }
+    readings
+}
+
+fn position(s: &str) -> Option<u32> {
+    if s.is_empty() || !s.bytes().all(|b| b.is_ascii_digit()) {
+        return None;
+    }
+    s.parse().ok().filter(|n| *n > 0)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::path::PathBuf;
+
+    fn args(list: &[&str]) -> Vec<String> {
+        list.iter().map(|s| (*s).to_owned()).collect()
+    }
+
+    fn parse_in(list: &[&str], existing: &[&str]) -> Result<Command, String> {
+        let existing: Vec<PathBuf> = existing.iter().map(PathBuf::from).collect();
+        parse_with(&args(list), Path::new("/work"), &|p| existing.iter().any(|e| e == p))
+    }
+
+    fn at(path: &str, line: Option<u32>, column: Option<u32>) -> Target {
+        Target { path: path.into(), line, column }
+    }
+
+    #[test]
+    fn paths_resolve_against_cwd() {
+        assert_eq!(
+            parse_in(&["src", "/abs/a.rs"], &["/work/src", "/abs/a.rs"]),
+            Ok(Command::Open(vec![at("/work/src", None, None), at("/abs/a.rs", None, None)]))
+        );
+        assert_eq!(parse_in(&[], &[]), Ok(Command::Open(vec![])));
+    }
+
+    #[test]
+    fn positions_split_only_when_the_whole_arg_is_missing() {
+        let files = ["/work/a.rs"];
+        assert_eq!(parse_in(&["a.rs:12"], &files), Ok(Command::Open(vec![at("/work/a.rs", Some(12), None)])));
+        assert_eq!(parse_in(&["a.rs:12:5"], &files), Ok(Command::Open(vec![at("/work/a.rs", Some(12), Some(5))])));
+        assert!(parse_in(&["a.rs:0"], &files).is_err());
+        assert!(parse_in(&["a.rs:x"], &files).is_err());
+        assert!(parse_in(&["missing.rs:3"], &files).is_err());
+    }
+
+    // Windows file names cannot contain `:`, and `b:2` reads as a path on drive B.
+    #[cfg(unix)]
+    #[test]
+    fn an_existing_name_with_a_colon_wins_over_a_position() {
+        let files = ["/work/b:2"];
+        assert_eq!(parse_in(&["b:2"], &files), Ok(Command::Open(vec![at("/work/b:2", None, None)])));
+        assert_eq!(parse_in(&["b:2:7"], &files), Ok(Command::Open(vec![at("/work/b:2", Some(7), None)])));
+    }
+
+    #[test]
+    fn windows_drive_colon_is_not_a_position() {
+        assert_eq!(split_position(r"C:\a.rs:10"), vec![(r"C:\a.rs", 10, None)]);
+        assert_eq!(split_position(r"C:\a.rs:10:2"), vec![(r"C:\a.rs", 10, Some(2)), (r"C:\a.rs:10", 2, None)]);
+        assert!(split_position(r"C:\a.rs").is_empty());
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn windows_absolute_and_unc_targets_keep_spaces_and_unicode() {
+        let local = PathBuf::from(r"C:\项目\my file.rs");
+        let network = PathBuf::from(r"\\server\share\folder name");
+        let command = parse_with(
+            &args(&[r"C:\项目\my file.rs:12:5", r"\\server\share\folder name"]),
+            Path::new(r"D:\work"),
+            &|path| path == local || path == network,
+        );
+        assert_eq!(
+            command,
+            Ok(Command::Open(vec![
+                Target { path: local, line: Some(12), column: Some(5) },
+                Target { path: network, line: None, column: None },
+            ]))
+        );
+    }
+
+    #[test]
+    fn line_and_column_flags_apply_to_the_next_path() {
+        let files = ["/work/a.rs", "/work/b.rs"];
+        assert_eq!(
+            parse_in(&["--line", "12", "--column=5", "a.rs", "b.rs"], &files),
+            Ok(Command::Open(vec![at("/work/a.rs", Some(12), Some(5)), at("/work/b.rs", None, None)]))
+        );
+        assert_eq!(
+            parse_in(&["--line=3", "a.rs:9:9"], &files),
+            Ok(Command::Open(vec![at("/work/a.rs", Some(3), None)]))
+        );
+        assert!(parse_in(&["--line", "0", "a.rs"], &files).is_err());
+        assert!(parse_in(&["--line"], &files).is_err());
+        assert!(parse_in(&["a.rs", "--line", "2"], &files).is_err());
+    }
+
+    #[test]
+    fn options() {
+        assert_eq!(parse_in(&["-h"], &[]), Ok(Command::Help));
+        assert_eq!(parse_in(&["--version"], &[]), Ok(Command::Version));
+        assert!(parse_in(&["--nope"], &[]).is_err());
+        assert_eq!(parse_in(&["--", "-h"], &["/work/-h"]), Ok(Command::Open(vec![at("/work/-h", None, None)])));
+    }
+
+    #[test]
+    fn existing_diff_command_is_supported() {
+        let files = ["/work/a.rs", "/work/b.rs"];
+        assert_eq!(
+            parse_in(&["diff", "a.rs", "b.rs"], &files),
+            Ok(Command::Diff(vec![at("/work/a.rs", None, None), at("/work/b.rs", None, None),]))
+        );
+        assert!(parse_in(&["diff", "a.rs"], &files).is_err());
+        assert_eq!(
+            parse_in(&["diff", "diff", "b.rs"], &["/work/diff", "/work/b.rs"]),
+            Ok(Command::Diff(vec![at("/work/diff", None, None), at("/work/b.rs", None, None),]))
+        );
+        assert_eq!(parse_in(&["--", "diff"], &["/work/diff"]), Ok(Command::Open(vec![at("/work/diff", None, None)])));
+        assert_eq!(
+            parse_in(&["--column=4", "a.rs", "b.rs"], &files),
+            Ok(Command::Open(vec![at("/work/a.rs", Some(1), Some(4)), at("/work/b.rs", None, None),]))
+        );
+    }
+}

crates/ide-cli/src/install.rs

@@ -0,0 +1,476 @@
+//! Installing the `openidea` command: a symlink on `PATH` to the launcher
+//! script in a macOS bundle, or a wrapper in a user's bin directory.
+
+use std::ffi::OsStr;
+use std::io;
+use std::path::{Path, PathBuf};
+
+pub const COMMAND: &str = "openidea";
+const LAUNCHER: &str = "Contents/Resources/bin/openidea";
+const SYSTEM_DIR: &str = "/usr/local/bin";
+
+/// The launcher script of the bundle whose executable is `exe`; `None` outside a bundle.
+pub fn bundled_launcher(exe: &Path) -> Option<PathBuf> {
+    let launcher = exe.parent()?.parent()?.parent()?.join(LAUNCHER);
+    launcher.is_file().then_some(launcher)
+}
+
+/// macOS runs a quarantined app from a random read-only copy until it is moved:
+/// a link there would break on the next launch.
+pub fn translocated(path: &Path) -> bool {
+    path.to_string_lossy().contains("/AppTranslocation/")
+}
+
+/// Where the link goes: `~/.local/bin` when it is on `path_var` (no administrator
+/// rights needed), else `/usr/local/bin`.
+pub fn link_dir(path_var: Option<&OsStr>, home: Option<&Path>) -> PathBuf {
+    let local = home.map(|h| h.join(".local/bin"));
+    match (path_var, local) {
+        (Some(var), Some(local)) if std::env::split_paths(var).any(|p| p == local) => local,
+        _ => PathBuf::from(SYSTEM_DIR),
+    }
+}
+
+/// Directories an earlier install may have used.
+pub fn link_dirs(home: Option<&Path>) -> Vec<PathBuf> {
+    home.map(|h| h.join(".local/bin")).into_iter().chain([PathBuf::from(SYSTEM_DIR)]).collect()
+}
+
+/// The installed links among `dirs` (any OpenIDEA bundle's launcher).
+pub fn installed(dirs: &[PathBuf]) -> Vec<PathBuf> {
+    dirs.iter().map(|d| d.join(COMMAND)).filter(|l| is_launcher_link(l)).collect()
+}
+
+fn is_launcher_link(link: &Path) -> bool {
+    std::fs::read_link(link).is_ok_and(|target| target.ends_with(LAUNCHER))
+}
+
+/// Links `dir/openidea` to `launcher`, asking for administrator rights when `dir`
+/// is not writable. Refuses to replace an `openidea` that is not ours.
+pub fn install(launcher: &Path, dir: &Path) -> io::Result<PathBuf> {
+    let link = dir.join(COMMAND);
+    if link.symlink_metadata().is_ok() && !is_launcher_link(&link) {
+        return Err(io::Error::new(
+            io::ErrorKind::AlreadyExists,
+            format!("{} already exists and is not an OpenIDEA command", link.display()),
+        ));
+    }
+    let direct = std::fs::create_dir_all(dir).and_then(|()| {
+        if link.symlink_metadata().is_ok() {
+            std::fs::remove_file(&link)?;
+        }
+        symlink(launcher, &link)
+    });
+    match direct {
+        Err(e) if e.kind() == io::ErrorKind::PermissionDenied => {
+            privileged(&format!("mkdir -p {} && ln -sfn {} {}", quote(dir), quote(launcher), quote(&link)))?
+        }
+        result => result?,
+    }
+    Ok(link)
+}
+
+/// Removes `links`, asking for administrator rights where needed.
+pub fn uninstall(links: &[PathBuf]) -> io::Result<()> {
+    for link in links {
+        match std::fs::remove_file(link) {
+            Err(e) if e.kind() == io::ErrorKind::PermissionDenied => privileged(&format!("rm -f {}", quote(link)))?,
+            result => result?,
+        }
+    }
+    Ok(())
+}
+
+#[cfg(unix)]
+fn symlink(target: &Path, link: &Path) -> io::Result<()> {
+    std::os::unix::fs::symlink(target, link)
+}
+
+#[cfg(not(unix))]
+fn symlink(_target: &Path, _link: &Path) -> io::Result<()> {
+    Err(io::Error::new(io::ErrorKind::Unsupported, "not supported on this platform"))
+}
+
+/// Runs `command` as root after the system's password prompt. Cancelling it is
+/// [`io::ErrorKind::Interrupted`].
+fn privileged(command: &str) -> io::Result<()> {
+    if !cfg!(target_os = "macos") {
+        return Err(io::Error::new(io::ErrorKind::PermissionDenied, "administrator rights required"));
+    }
+    let script = format!("do shell script \"{}\" with administrator privileges", applescript_escape(command));
+    let output = std::process::Command::new("/usr/bin/osascript").arg("-e").arg(script).output()?;
+    if output.status.success() {
+        return Ok(());
+    }
+    let message = String::from_utf8_lossy(&output.stderr).trim().to_owned();
+    // "User canceled. (-128)"
+    let kind = if message.contains("(-128)") { io::ErrorKind::Interrupted } else { io::ErrorKind::PermissionDenied };
+    Err(io::Error::new(kind, message))
+}
+
+fn quote(path: &Path) -> String {
+    format!("'{}'", path.to_string_lossy().replace('\'', r"'\''"))
+}
+
+fn applescript_escape(s: &str) -> String {
+    s.replace('\\', r"\\").replace('"', "\\\"")
+}
+
+const WRAPPER_MARKER: &str = "OpenIDEA command launcher v1";
+
+/// AppImages remount their executable on every launch. Keep the original image path.
+pub fn stable_executable(exe: &Path, appimage: Option<&Path>) -> io::Result<PathBuf> {
+    let path = appimage.unwrap_or(exe);
+    if !path.is_absolute() || !path.is_file() {
+        return Err(io::Error::new(io::ErrorKind::NotFound, "the OpenIDEA executable must be in a permanent location"));
+    }
+    Ok(path.to_path_buf())
+}
+
+pub fn wrapper_path(dir: &Path, windows: bool) -> PathBuf {
+    dir.join(if windows { "openidea.cmd" } else { COMMAND })
+}
+
+fn wrapper(exe: &Path, windows: bool) -> io::Result<String> {
+    let exe =
+        exe.to_str().ok_or_else(|| io::Error::new(io::ErrorKind::InvalidInput, "the executable path is not UTF-8"))?;
+    if exe.contains(['\r', '\n']) || (windows && exe.contains('"')) {
+        return Err(io::Error::new(io::ErrorKind::InvalidInput, "the executable path contains unsupported characters"));
+    }
+    Ok(if windows {
+        format!(
+            "@echo off\r\nrem {WRAPPER_MARKER}\r\nsetlocal DisableDelayedExpansion\r\nfor /f \"tokens=2 delims=:\" %%c in ('\"%SystemRoot%\\System32\\chcp.com\"') do set \"_openidea_codepage=%%c\"\r\n\"%SystemRoot%\\System32\\chcp.com\" 65001 >nul\r\n\"{}\" --cli %*\r\nset \"_openidea_exit=%errorlevel%\"\r\n\"%SystemRoot%\\System32\\chcp.com\" %_openidea_codepage% >nul\r\nexit /b %_openidea_exit%\r\n",
+            exe.replace('%', "%%")
+        )
+    } else {
+        format!("#!/bin/sh\n# {WRAPPER_MARKER}\nexec {} --cli \"$@\"\n", quote(Path::new(exe)))
+    })
+}
+
+pub fn is_wrapper(path: &Path, windows: bool) -> bool {
+    path.symlink_metadata().is_ok_and(|meta| meta.is_file() && !meta.file_type().is_symlink())
+        && std::fs::read_to_string(path).is_ok_and(|text| {
+            text.lines().nth(1) == Some(&format!("{} {WRAPPER_MARKER}", if windows { "rem" } else { "#" }))
+        })
+}
+
+/// Never follows or overwrites a foreign file, even if it has the same command name.
+pub fn install_wrapper(exe: &Path, dir: &Path, windows: bool) -> io::Result<PathBuf> {
+    use std::io::Write;
+    let text = wrapper(exe, windows)?;
+    let path = wrapper_path(dir, windows);
+    if path.symlink_metadata().is_ok() {
+        if !is_wrapper(&path, windows) {
+            return Err(io::Error::new(
+                io::ErrorKind::AlreadyExists,
+                format!("{} already exists and is not an OpenIDEA command", path.display()),
+            ));
+        }
+        std::fs::remove_file(&path)?;
+    }
+    std::fs::create_dir_all(dir)?;
+    let mut file = std::fs::OpenOptions::new().write(true).create_new(true).open(&path)?;
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        file.set_permissions(std::fs::Permissions::from_mode(0o755))?;
+    }
+    file.write_all(text.as_bytes())?;
+    Ok(path)
+}
+
+pub fn uninstall_wrapper(dir: &Path, windows: bool) -> io::Result<Vec<PathBuf>> {
+    let path = wrapper_path(dir, windows);
+    if !is_wrapper(&path, windows) {
+        return Ok(vec![]);
+    }
+    std::fs::remove_file(&path)?;
+    Ok(vec![path])
+}
+
+/// Preserve every unrelated PATH entry, including expandable environment variables.
+pub fn windows_path(current: &str, dir: &str, add: bool) -> Option<String> {
+    fn equal(a: &str, b: &str) -> bool {
+        a.trim().trim_matches('"').trim_end_matches(['\\', '/']).eq_ignore_ascii_case(b.trim_end_matches(['\\', '/']))
+    }
+    let found = current.split(';').any(|entry| equal(entry, dir));
+    if add {
+        if found {
+            return None;
+        }
+        Some(format!("{dir}{}{current}", if current.is_empty() { "" } else { ";" }))
+    } else if found {
+        Some(current.split(';').filter(|entry| !equal(entry, dir)).collect::<Vec<_>>().join(";"))
+    } else {
+        None
+    }
+}
+
+#[cfg(windows)]
+pub fn update_user_path(dir: &Path, add: bool) -> io::Result<()> {
+    use winreg::{
+        RegKey,
+        enums::{HKEY_CURRENT_USER, REG_EXPAND_SZ},
+        types::{FromRegValue, ToRegValue},
+    };
+    let (environment, _) = RegKey::predef(HKEY_CURRENT_USER).create_subkey("Environment")?;
+    let raw = match environment.get_raw_value("Path") {
+        Ok(raw) => Some(raw),
+        Err(e) if e.kind() == io::ErrorKind::NotFound => None,
+        Err(e) => return Err(e),
+    };
+    let current = raw.as_ref().map(String::from_reg_value).transpose()?.unwrap_or_default();
+    let Some(updated) = windows_path(&current, &dir.to_string_lossy(), add) else { return Ok(()) };
+    let mut value = updated.to_reg_value();
+    value.vtype = raw.as_ref().map_or(REG_EXPAND_SZ, |raw| raw.vtype.clone());
+    environment.set_raw_value("Path", &value)?;
+    let message: Vec<u16> = "Environment\0".encode_utf16().collect();
+    // SAFETY: the terminated string stays alive for this bounded synchronous broadcast.
+    unsafe {
+        windows_sys::Win32::UI::WindowsAndMessaging::SendMessageTimeoutW(
+            windows_sys::Win32::UI::WindowsAndMessaging::HWND_BROADCAST,
+            windows_sys::Win32::UI::WindowsAndMessaging::WM_SETTINGCHANGE,
+            0,
+            message.as_ptr() as isize,
+            windows_sys::Win32::UI::WindowsAndMessaging::SMTO_ABORTIFHUNG,
+            1000,
+            std::ptr::null_mut(),
+        );
+    }
+    Ok(())
+}
+
+pub struct Installation {
+    pub path: PathBuf,
+    /// Some when the user needs to add this directory to their shell's PATH.
+    pub path_directory: Option<PathBuf>,
+}
+
+fn resolves_to(path_var: Option<&OsStr>, command: &Path) -> bool {
+    path_var
+        .and_then(|path| std::env::split_paths(path).map(|dir| dir.join(COMMAND)).find(|candidate| candidate.is_file()))
+        .is_some_and(|candidate| candidate == command)
+}
+
+fn user_bin() -> io::Result<PathBuf> {
+    if cfg!(windows) {
+        dirs::data_local_dir().map(|dir| dir.join("OpenIDEA/bin"))
+    } else {
+        dirs::home_dir().map(|dir| dir.join(".local/bin"))
+    }
+    .ok_or_else(|| io::Error::new(io::ErrorKind::NotFound, "no user directory for the openidea command"))
+}
+
+pub fn install_current() -> io::Result<Installation> {
+    let exe = std::env::current_exe()?;
+    if cfg!(target_os = "macos") {
+        let launcher = bundled_launcher(&exe).ok_or_else(|| {
+            io::Error::new(io::ErrorKind::NotFound, "install the command from the packaged OpenIDEA app")
+        })?;
+        if translocated(&launcher) {
+            return Err(io::Error::new(
+                io::ErrorKind::PermissionDenied,
+                "move OpenIDEA to the Applications folder first",
+            ));
+        }
+        let dir = link_dir(std::env::var_os("PATH").as_deref(), dirs::home_dir().as_deref());
+        return Ok(Installation { path: install(&launcher, &dir)?, path_directory: None });
+    }
+    let image = if cfg!(target_os = "linux") { std::env::var_os("APPIMAGE").map(PathBuf::from) } else { None };
+    let exe = stable_executable(&exe, image.as_deref())?;
+    let dir = user_bin()?;
+    let path = install_wrapper(&exe, &dir, cfg!(windows))?;
+    #[cfg(windows)]
+    update_user_path(&dir, true)?;
+    let on_path = cfg!(windows) || resolves_to(std::env::var_os("PATH").as_deref(), &path);
+    Ok(Installation { path, path_directory: (!on_path).then_some(dir) })
+}
+
+pub fn uninstall_current() -> io::Result<Vec<PathBuf>> {
+    if cfg!(target_os = "macos") {
+        let links = installed(&link_dirs(dirs::home_dir().as_deref()));
+        uninstall(&links)?;
+        return Ok(links);
+    }
+    let dir = user_bin()?;
+    let path = wrapper_path(&dir, cfg!(windows));
+    if is_wrapper(&path, cfg!(windows)) {
+        #[cfg(windows)]
+        update_user_path(&dir, false)?;
+        return uninstall_wrapper(&dir, cfg!(windows));
+    }
+    Ok(vec![])
+}
+
+#[cfg(test)]
+mod wrapper_tests {
+    use super::*;
+
+    #[test]
+    fn wrappers_install_update_and_remove_only_their_own_files() {
+        for windows in [false, true] {
+            let dir = tempfile::tempdir().unwrap();
+            let exe = dir.path().join("App folder/程序 & it's 100%.exe");
+            let path = install_wrapper(&exe, dir.path(), windows).unwrap();
+            assert!(is_wrapper(&path, windows));
+            assert_eq!(install_wrapper(&exe, dir.path(), windows).unwrap(), path);
+            assert_eq!(uninstall_wrapper(dir.path(), windows).unwrap(), vec![path.clone()]);
+            assert!(uninstall_wrapper(dir.path(), windows).unwrap().is_empty());
+            std::fs::write(&path, "foreign command").unwrap();
+            assert_eq!(install_wrapper(&exe, dir.path(), windows).unwrap_err().kind(), io::ErrorKind::AlreadyExists);
+            assert!(uninstall_wrapper(dir.path(), windows).unwrap().is_empty());
+            assert_eq!(std::fs::read_to_string(&path).unwrap(), "foreign command");
+        }
+    }
+
+    #[test]
+    fn path_changes_keep_other_entries_and_do_not_duplicate_the_command_dir() {
+        let dir = r"C:\Users\用户\OpenIDEA\bin";
+        let initial = r"%USERPROFILE%\tools;C:\other";
+        let updated = windows_path(initial, dir, true).unwrap();
+        assert_eq!(updated, format!("{dir};{initial}"));
+        assert_eq!(windows_path(&updated, dir, true), None);
+        assert_eq!(windows_path(&updated, dir, false).as_deref(), Some(initial));
+        assert_eq!(
+            windows_path(&format!("\"{dir}\\\";C:\\other"), &dir.to_uppercase(), false).as_deref(),
+            Some(r"C:\other")
+        );
+        assert_eq!(windows_path(initial, dir, false), None);
+    }
+
+    #[test]
+    fn appimage_uses_the_persistent_image_not_the_mounted_binary() {
+        let dir = tempfile::tempdir().unwrap();
+        let image = dir.path().join("OpenIDEA.AppImage");
+        std::fs::write(&image, "image").unwrap();
+        assert_eq!(stable_executable(Path::new("/tmp/.mount_App/usr/bin/openidea"), Some(&image)).unwrap(), image);
+        assert_eq!(stable_executable(&image, None).unwrap(), image);
+        assert!(stable_executable(Path::new("missing"), None).is_err());
+    }
+
+    #[test]
+    fn detects_a_system_binary_shadowing_the_linux_wrapper() {
+        let dir = tempfile::tempdir().unwrap();
+        let system = dir.path().join("system");
+        let user = dir.path().join("user");
+        for bin in [&system, &user] {
+            std::fs::create_dir_all(bin).unwrap();
+            std::fs::write(bin.join(COMMAND), "command").unwrap();
+        }
+        let path = std::env::join_paths([&system, &user]).unwrap();
+        assert!(!resolves_to(Some(&path), &user.join(COMMAND)));
+        let path = std::env::join_paths([&user, &system]).unwrap();
+        assert!(resolves_to(Some(&path), &user.join(COMMAND)));
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn posix_wrapper_preserves_arguments_and_exit_status() {
+        use std::os::unix::fs::PermissionsExt;
+        let dir = tempfile::tempdir().unwrap();
+        let exe = dir.path().join("app & it's $dollar `quoted` \"double\"");
+        std::fs::write(&exe, "#!/bin/sh\nprintf '%s\\n' \"$@\"\nexit 7\n").unwrap();
+        std::fs::set_permissions(&exe, std::fs::Permissions::from_mode(0o755)).unwrap();
+        let path = install_wrapper(&exe, &dir.path().join("bin"), false).unwrap();
+        let output = std::process::Command::new(path).args(["a b", "中文", "x'$`&"]).output().unwrap();
+        assert_eq!(output.status.code(), Some(7));
+        assert_eq!(String::from_utf8(output.stdout).unwrap(), "--cli\na b\n中文\nx'$`&\n");
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn cmd_wrapper_preserves_arguments_and_exit_status() {
+        use std::os::windows::process::CommandExt;
+        let dir = tempfile::tempdir().unwrap();
+        let exe = dir.path().join("程序 & 100% !special!.exe");
+        let source = dir.path().join("helper.rs");
+        std::fs::write(
+            &source,
+            r#"fn main() { for arg in std::env::args().skip(1) { println!("{arg}"); } std::process::exit(7); }"#,
+        )
+        .unwrap();
+        let compiled = std::process::Command::new("rustc")
+            .args(["--crate-name", "launcher_test"])
+            .arg(&source)
+            .arg("-o")
+            .arg(&exe)
+            .output()
+            .unwrap();
+        assert!(compiled.status.success(), "{}", String::from_utf8_lossy(&compiled.stderr));
+        let path = install_wrapper(&exe, &dir.path().join("bin"), true).unwrap();
+        std::fs::write(dir.path().join("chcp.cmd"), "@echo malicious-chcp\r\nexit /b 99\r\n").unwrap();
+        let output = std::process::Command::new("cmd.exe")
+            .current_dir(dir.path())
+            .args(["/d", "/s", "/c"])
+            .raw_arg(format!("\"\"{}\" \"a b\" \"中文\" \"x&y\"\"", path.display()))
+            .output()
+            .unwrap();
+        assert_eq!(output.status.code(), Some(7));
+        assert_eq!(String::from_utf8(output.stdout).unwrap().replace("\r\n", "\n"), "--cli\na b\n中文\nx&y\n");
+        let check = dir.path().join("check.cmd");
+        std::fs::write(&check, "@echo off\r\nfor /f \"tokens=2 delims=:\" %%c in ('\"%SystemRoot%\\System32\\chcp.com\"') do set \"before=%%c\"\r\ncall \"%~dp0bin\\openidea.cmd\" example\r\nset \"code=%errorlevel%\"\r\nfor /f \"tokens=2 delims=:\" %%c in ('\"%SystemRoot%\\System32\\chcp.com\"') do set \"after=%%c\"\r\nif not \"%before%\"==\"%after%\" exit /b 99\r\nexit /b %code%\r\n").unwrap();
+        let output = std::process::Command::new("cmd.exe")
+            .current_dir(dir.path())
+            .args(["/d", "/s", "/c"])
+            .raw_arg(format!("\"\"{}\"\"", check.display()))
+            .output()
+            .unwrap();
+        assert_eq!(output.status.code(), Some(7));
+        assert!(!String::from_utf8_lossy(&output.stdout).contains("malicious-chcp"));
+    }
+}
+
+#[cfg(all(test, unix))]
+mod tests {
+    use super::*;
+
+    fn bundle(root: &Path) -> (PathBuf, PathBuf) {
+        let app = root.join("OpenIDEA.app");
+        let exe = app.join("Contents/MacOS/openidea");
+        let launcher = app.join(LAUNCHER);
+        std::fs::create_dir_all(exe.parent().unwrap()).unwrap();
+        std::fs::create_dir_all(launcher.parent().unwrap()).unwrap();
+        std::fs::write(&exe, "").unwrap();
+        std::fs::write(&launcher, "").unwrap();
+        (exe, launcher)
+    }
+
+    #[test]
+    fn finds_the_launcher_of_a_bundle_only() {
+        let dir = tempfile::tempdir().unwrap();
+        let (exe, launcher) = bundle(dir.path());
+        assert_eq!(bundled_launcher(&exe), Some(launcher));
+        assert_eq!(bundled_launcher(&dir.path().join("target/debug/openidea")), None);
+        assert!(translocated(Path::new("/private/var/folders/x/AppTranslocation/ABC/d/OpenIDEA.app")));
+    }
+
+    #[test]
+    fn prefers_local_bin_on_path() {
+        let home = Path::new("/Users/u");
+        let path = std::env::join_paths(["/usr/bin", "/Users/u/.local/bin"]).unwrap();
+        assert_eq!(link_dir(Some(&path), Some(home)), home.join(".local/bin"));
+        assert_eq!(link_dir(Some(OsStr::new("/usr/bin")), Some(home)), PathBuf::from(SYSTEM_DIR));
+        assert_eq!(link_dir(None, Some(home)), PathBuf::from(SYSTEM_DIR));
+    }
+
+    #[test]
+    fn install_replaces_its_own_link_but_not_other_files() {
+        let dir = tempfile::tempdir().unwrap();
+        let (_, launcher) = bundle(dir.path());
+        let bin = dir.path().join("bin");
+        let link = install(&launcher, &bin).unwrap();
+        assert_eq!(std::fs::read_link(&link).unwrap(), launcher);
+        assert_eq!(install(&launcher, &bin).unwrap(), link);
+        assert_eq!(installed(std::slice::from_ref(&bin)), vec![link.clone()]);
+        uninstall(&installed(std::slice::from_ref(&bin))).unwrap();
+        assert!(installed(std::slice::from_ref(&bin)).is_empty());
+        std::fs::write(&link, "someone else's").unwrap();
+        assert_eq!(install(&launcher, &bin).unwrap_err().kind(), io::ErrorKind::AlreadyExists);
+    }
+
+    #[test]
+    fn quoting() {
+        assert_eq!(quote(Path::new("/a b/it's")), r"'/a b/it'\''s'");
+        assert_eq!(applescript_escape(r#"ln "a\b""#), r#"ln \"a\\b\""#);
+    }
+}

crates/ide-cli/src/lib.rs

@@ -0,0 +1,72 @@
+//! The `openidea` command.
+//!
+//! The command is the app's own executable run in CLI mode: it parses its
+//! arguments ([`args`]), sends one [`Request`] to the running app over a local
+//! socket ([`socket`]) and exits. [`install`] links the bundle's launcher
+//! script into a directory on `PATH`.
+
+pub mod args;
+pub mod install;
+pub mod socket;
+
+use serde::{Deserialize, Serialize};
+use std::path::PathBuf;
+
+/// Bumped when [`Request`] changes incompatibly; an app still running an older
+/// version answers with an error instead of misreading it.
+pub const PROTOCOL_VERSION: u32 = 1;
+
+/// A file or folder to open, with an optional 1-based position in a file.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Target {
+    /// Absolute.
+    pub path: PathBuf,
+    pub line: Option<u32>,
+    pub column: Option<u32>,
+}
+
+/// What the command asks the running app to do. No targets: bring the app to the front.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Request {
+    pub version: u32,
+    pub targets: Vec<Target>,
+    #[serde(default)]
+    pub diff: bool,
+}
+
+impl Request {
+    pub fn open(targets: Vec<Target>) -> Self {
+        Self { version: PROTOCOL_VERSION, targets, diff: false }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(tag = "kind", rename_all = "camelCase")]
+pub enum Response {
+    Ok,
+    Error { message: String },
+}
+
+/// A GUI subsystem executable inherits redirected handles, but needs its parent's
+/// console for interactive help and errors. Batch launchers wait for this process.
+#[cfg(windows)]
+pub fn attach_console() {
+    use windows_sys::Win32::Storage::FileSystem::{FILE_TYPE_DISK, FILE_TYPE_PIPE, GetFileType};
+    use windows_sys::Win32::System::Console::{
+        ATTACH_PARENT_PROCESS, AttachConsole, GetStdHandle, STD_ERROR_HANDLE, STD_INPUT_HANDLE, STD_OUTPUT_HANDLE,
+        SetStdHandle,
+    };
+    // SAFETY: attaches only this CLI process, without allocating a new console.
+    unsafe {
+        let redirected = [STD_INPUT_HANDLE, STD_OUTPUT_HANDLE, STD_ERROR_HANDLE].map(|kind| {
+            let handle = GetStdHandle(kind);
+            (kind, handle, matches!(GetFileType(handle), FILE_TYPE_DISK | FILE_TYPE_PIPE))
+        });
+        AttachConsole(ATTACH_PARENT_PROCESS);
+        for (kind, handle, keep) in redirected {
+            if keep {
+                SetStdHandle(kind, handle);
+            }
+        }
+    }
+}

crates/ide-cli/src/socket.rs

@@ -0,0 +1,266 @@
+//! The local socket the running app listens on: one JSON [`Request`] line in,
+//! one [`Response`] line out. Unix domain sockets or Windows named pipes.
+
+use crate::{Request, Response};
+use std::io;
+use std::path::{Path, PathBuf};
+use std::time::Duration;
+
+const TIMEOUT: Duration = Duration::from_secs(10);
+const MAX_MESSAGE: u64 = 1024 * 1024;
+
+fn answer(line: &str, handle: &dyn Fn(Request) -> Response) -> Response {
+    match serde_json::from_str::<Request>(line) {
+        Ok(request) if request.version == crate::PROTOCOL_VERSION && (!request.diff || request.targets.len() == 2) => {
+            handle(request)
+        }
+        Ok(_) => Response::Error { message: "unsupported or invalid CLI request".into() },
+        Err(e) => Response::Error { message: format!("invalid request: {e}") },
+    }
+}
+
+/// The socket of the app with bundle identifier `identifier`. The name is a hash:
+/// socket paths are limited to about 100 bytes, and development identifiers are long.
+pub fn socket_path(identifier: &str) -> Option<PathBuf> {
+    if cfg!(windows) {
+        let user = dirs::data_local_dir()?;
+        return Some(PathBuf::from(format!(
+            r"\\.\pipe\openidea-{:016x}",
+            fnv1a(&format!("{}:{identifier}", user.display()))
+        )));
+    }
+    let dir = if cfg!(target_os = "macos") { dirs::cache_dir() } else { dirs::runtime_dir().or_else(dirs::cache_dir) };
+    Some(dir?.join(format!("openidea-{:016x}.sock", fnv1a(identifier))))
+}
+
+fn fnv1a(s: &str) -> u64 {
+    s.bytes().fold(0xcbf29ce484222325, |hash, byte| (hash ^ u64::from(byte)).wrapping_mul(0x100000001b3))
+}
+
+#[cfg(unix)]
+mod imp {
+    use super::*;
+    use std::io::{BufRead, BufReader, Read, Write};
+    use std::os::unix::fs::{FileTypeExt, PermissionsExt};
+    use std::os::unix::net::{UnixListener, UnixStream};
+
+    pub fn send(socket: &Path, request: &Request) -> io::Result<Response> {
+        let stream = UnixStream::connect(socket)?;
+        stream.set_read_timeout(Some(TIMEOUT))?;
+        stream.set_write_timeout(Some(TIMEOUT))?;
+        write_line(&stream, request)?;
+        let mut reply = String::new();
+        BufReader::new((&stream).take(MAX_MESSAGE)).read_line(&mut reply)?;
+        Ok(serde_json::from_str(&reply)?)
+    }
+
+    pub fn serve(socket: &Path, handle: impl Fn(Request) -> Response + Send + 'static) -> io::Result<()> {
+        let listener = bind(socket)?;
+        std::thread::Builder::new().name("cli-socket".into()).spawn(move || {
+            for stream in listener.incoming().flatten() {
+                if let Err(e) = serve_one(&stream, &handle) {
+                    tracing::warn!("cli request failed: {e}");
+                }
+            }
+        })?;
+        Ok(())
+    }
+
+    /// Binds `socket`, replacing a stale file no one answers on.
+    fn bind(socket: &Path) -> io::Result<UnixListener> {
+        if let Some(dir) = socket.parent() {
+            std::fs::create_dir_all(dir)?;
+        }
+        let listener = match UnixListener::bind(socket) {
+            Err(e) if e.kind() == io::ErrorKind::AddrInUse => {
+                if !std::fs::symlink_metadata(socket)?.file_type().is_socket() || UnixStream::connect(socket).is_ok() {
+                    return Err(e);
+                }
+                std::fs::remove_file(socket)?;
+                UnixListener::bind(socket)?
+            }
+            bound => bound?,
+        };
+        std::fs::set_permissions(socket, std::fs::Permissions::from_mode(0o600))?;
+        Ok(listener)
+    }
+
+    fn serve_one(stream: &UnixStream, handle: &dyn Fn(Request) -> Response) -> io::Result<()> {
+        stream.set_read_timeout(Some(TIMEOUT))?;
+        stream.set_write_timeout(Some(TIMEOUT))?;
+        let mut line = String::new();
+        BufReader::new(stream.take(MAX_MESSAGE)).read_line(&mut line)?;
+        write_line(stream, &answer(&line, handle))
+    }
+
+    fn write_line(mut stream: &UnixStream, value: &impl serde::Serialize) -> io::Result<()> {
+        let mut line = serde_json::to_string(value)?;
+        line.push('\n');
+        stream.write_all(line.as_bytes())
+    }
+}
+
+#[cfg(windows)]
+mod imp {
+    use super::*;
+    use tokio::io::{AsyncBufReadExt, AsyncReadExt, AsyncWriteExt, BufReader};
+    use tokio::net::windows::named_pipe::{ClientOptions, ServerOptions};
+
+    fn runtime() -> io::Result<tokio::runtime::Runtime> {
+        tokio::runtime::Builder::new_current_thread().enable_all().build()
+    }
+
+    pub fn send(socket: &Path, request: &Request) -> io::Result<Response> {
+        runtime()?.block_on(async {
+            tokio::time::timeout(TIMEOUT, async {
+                let mut pipe = loop {
+                    match ClientOptions::new().open(socket) {
+                        Ok(pipe) => break pipe,
+                        // All existing instances are busy; wait instead of starting another app.
+                        Err(e) if e.raw_os_error() == Some(231) => tokio::time::sleep(Duration::from_millis(10)).await,
+                        Err(e) => return Err(e),
+                    }
+                };
+                let mut line = serde_json::to_vec(request)?;
+                line.push(b'\n');
+                pipe.write_all(&line).await?;
+                let mut reply = String::new();
+                BufReader::new((&mut pipe).take(MAX_MESSAGE)).read_line(&mut reply).await?;
+                pipe.write_all(b"\n").await?;
+                Ok(serde_json::from_str(&reply)?)
+            })
+            .await
+            .map_err(|_| io::Error::new(io::ErrorKind::TimedOut, "CLI request timed out"))?
+        })
+    }
+
+    pub fn serve(socket: &Path, handle: impl Fn(Request) -> Response + Send + 'static) -> io::Result<()> {
+        let socket = socket.to_owned();
+        let (ready, receiver) = std::sync::mpsc::sync_channel(1);
+        std::thread::Builder::new().name("cli-pipe".into()).spawn(move || {
+            let runtime = match runtime() {
+                Ok(runtime) => runtime,
+                Err(e) => {
+                    let _ = ready.send(Err(e));
+                    return;
+                }
+            };
+            runtime.block_on(async move {
+                let mut pipe = match ServerOptions::new().first_pipe_instance(true).create(&socket) {
+                    Ok(pipe) => pipe,
+                    Err(e) => {
+                        let _ = ready.send(Err(e));
+                        return;
+                    }
+                };
+                let _ = ready.send(Ok(()));
+                loop {
+                    if let Err(e) = pipe.connect().await {
+                        tracing::warn!("CLI pipe connection failed: {e}");
+                        return;
+                    }
+                    // Keep an instance bound while answering, so another process cannot take the name.
+                    let next = match ServerOptions::new().create(&socket) {
+                        Ok(next) => next,
+                        Err(e) => {
+                            tracing::warn!("cannot create CLI pipe: {e}");
+                            return;
+                        }
+                    };
+                    let reply = tokio::time::timeout(TIMEOUT, async {
+                        let mut line = String::new();
+                        BufReader::new((&mut pipe).take(MAX_MESSAGE)).read_line(&mut line).await?;
+                        let mut reply = serde_json::to_vec(&answer(&line, &handle))?;
+                        reply.push(b'\n');
+                        pipe.write_all(&reply).await?;
+                        // Wait until the client has drained the reply before closing its instance.
+                        pipe.read_exact(&mut [0u8; 1]).await.map(|_| ())
+                    })
+                    .await;
+                    if !matches!(reply, Ok(Ok(()))) {
+                        tracing::warn!("CLI pipe request failed: {reply:?}");
+                    }
+                    // Dropping after the write lets the client drain its reply before disconnecting.
+                    drop(pipe);
+                    pipe = next;
+                }
+            });
+        })?;
+        receiver.recv().map_err(|_| io::Error::other("CLI pipe thread stopped"))?
+    }
+}
+
+/// Sends `request` to the app listening on `socket` and waits for its answer.
+pub use imp::send;
+/// Answers requests on `socket` with `handle`, on a thread of its own.
+pub use imp::serve;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn socket_names_separate_identifiers_and_stay_short() {
+        let release = socket_path("ai.l0ng.openidea").unwrap();
+        let dev = socket_path("ai.l0ng.openidea.dev.w158e9c5954b7bf64").unwrap();
+        assert_ne!(release, dev);
+        assert!(dev.as_os_str().len() < 100 || cfg!(unix));
+    }
+
+    #[test]
+    fn answers_only_its_protocol_version() {
+        let ok = |_: Request| Response::Ok;
+        assert_eq!(answer(&serde_json::to_string(&Request::open(vec![])).unwrap(), &ok), Response::Ok);
+        let old = r#"{"version":0,"targets":[]}"#;
+        assert!(matches!(answer(old, &ok), Response::Error { .. }));
+        assert!(matches!(answer("garbage", &ok), Response::Error { .. }));
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn named_pipe_round_trip() {
+        let socket = socket_path(&format!("test-{}", std::process::id())).unwrap();
+        let (tx, rx) = std::sync::mpsc::channel();
+        serve(&socket, move |request| {
+            tx.send(request).unwrap();
+            Response::Ok
+        })
+        .unwrap();
+        for _ in 0..2 {
+            let target = crate::Target { path: r"C:\项目\my file.rs".into(), line: Some(3), column: Some(2) };
+            assert_eq!(send(&socket, &Request::open(vec![target.clone()])).unwrap(), Response::Ok);
+            assert_eq!(rx.recv_timeout(TIMEOUT).unwrap().targets, vec![target]);
+        }
+        assert!(serve(&socket, |_| Response::Ok).is_err());
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn request_round_trip_and_stale_socket() {
+        let dir = tempfile::tempdir().unwrap();
+        let socket = dir.path().join("cli.sock");
+        // A file left by an app that exited without removing it.
+        drop(std::os::unix::net::UnixListener::bind(&socket).unwrap());
+        let (tx, rx) = std::sync::mpsc::channel();
+        serve(&socket, move |request| {
+            tx.send(request).unwrap();
+            Response::Ok
+        })
+        .unwrap();
+        let target = crate::Target { path: "/p/a.rs".into(), line: Some(3), column: None };
+        assert_eq!(send(&socket, &Request::open(vec![target.clone()])).unwrap(), Response::Ok);
+        assert_eq!(rx.recv().unwrap().targets, vec![target]);
+        // A live server keeps its socket.
+        assert_eq!(serve(&socket, |_| Response::Ok).unwrap_err().kind(), io::ErrorKind::AddrInUse);
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn refuses_to_remove_an_unrelated_file() {
+        let dir = tempfile::tempdir().unwrap();
+        let socket = dir.path().join("cli.sock");
+        std::fs::write(&socket, "keep").unwrap();
+        assert!(serve(&socket, |_| Response::Ok).is_err());
+        assert_eq!(std::fs::read_to_string(&socket).unwrap(), "keep");
+    }
+}

crates/ide-core/src/event.rs

@@ -10,9 +10,23 @@ use serde::{Deserialize, Serialize};
 use specta::Type;
 use std::sync::Arc;
 
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(tag = "type", rename_all = "camelCase", rename_all_fields = "camelCase")]
+pub enum McpUiRequest {
+    Confirm { client: String, tool: String, subject: String, project: String, detail: Option<String> },
+    OpenFile { path: crate::IpcPath, line: Option<u32>, column: Option<u32> },
+}
+
 #[derive(Clone, Debug, Serialize, Deserialize, Type)]
 #[serde(tag = "type", rename_all = "camelCase", rename_all_fields = "camelCase")]
 pub enum IdeEvent {
+    McpRequest {
+        id: u32,
+        request: McpUiRequest,
+    },
+    McpRequestClosed {
+        id: u32,
+    },
     /// Project window membership or selection changed.
     WindowGroupsChanged,
     /// A window entered or left full screen, itself or as a member of a full-screen window group.

crates/ide-core/src/settings.rs

@@ -61,6 +61,8 @@ pub struct Settings {
     pub cmake: CMakeSettings,
     /// Tools › Agents › Chat.
     pub agents: AgentSettings,
+    /// Tools › MCP Server (global only).
+    pub mcp_server: McpServerSettings,
     /// Plugin settings (`[contributes.settings]`): plugin id → its values by key.
     #[specta(type = BTreeMap<String, BTreeMap<String, specta_typescript::Unknown>>)]
     pub plugins: BTreeMap<String, serde_json::Map<String, serde_json::Value>>,
@@ -86,6 +88,14 @@ impl Default for AgentSettings {
     }
 }
 
+/// Tools › MCP Server: agents use the IDE's built-in tools.
+#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(default, rename_all = "camelCase")]
+pub struct McpServerSettings {
+    /// Serve the tools on 127.0.0.1 while the IDE runs.
+    pub enabled: bool,
+}
+
 /// Absent profiles retain automatic discovery for existing projects.
 #[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize, Type)]
 #[serde(default, rename_all = "camelCase")]
@@ -230,6 +240,7 @@ impl Default for Settings {
             run_targets: Vec::new(),
             cmake: CMakeSettings::default(),
             agents: AgentSettings::default(),
+            mcp_server: McpServerSettings::default(),
             plugins: BTreeMap::new(),
         }
     }
@@ -915,6 +926,8 @@ pub struct MavenSettings {
     pub home: String,
     /// User `settings.xml` (`-s`); empty = `~/.m2/settings.xml`.
     pub user_settings: String,
+    /// Toolchains file (`-t`); empty = `~/.m2/toolchains.xml`.
+    pub toolchains: String,
     /// Local repository (`-Dmaven.repo.local`); empty = from `settings.xml`.
     pub local_repository: String,
     /// Run Maven through the Maven Daemon (`mvnd`) for faster builds. mvnd embeds
@@ -926,9 +939,25 @@ pub struct MavenSettings {
     /// Thread count of Maven builds (`-T`): a number of threads (`4`) or a core
     /// multiplier (`2C`, `2.5C`); empty = Maven's default (one thread per module).
     pub threads: String,
+    /// Active Maven profiles (`-P`), comma-separated; empty leaves profiles to the POM/settings.
+    pub active_profiles: String,
 }
 
 impl MavenSettings {
+    /// Settings profiles followed by the Maven tool window's choices.
+    pub fn profiles(&self, choices: &[String]) -> Vec<String> {
+        let mut profiles = Vec::new();
+        for profile in self.active_profiles.split(',').chain(choices.iter().map(String::as_str)).map(str::trim) {
+            if !profile.is_empty() && !profiles.iter().any(|p| p == profile) {
+                profiles.push(profile.to_owned());
+            }
+        }
+        let excluded: Vec<String> =
+            profiles.iter().filter_map(|p| p.strip_prefix(['!', '-']).map(str::to_owned)).collect();
+        profiles.retain(|p| !excluded.contains(p));
+        profiles
+    }
+
     /// The `-T` value when it is one Maven accepts: a thread count (`4`) or a
     /// core multiplier with an optional decimal fraction (`1C`, `2.5C`).
     /// Anything else is dropped: a bad `-T` would make every Maven run fail.
@@ -1388,6 +1417,24 @@ mod maven_linkage_tests {
         assert_eq!(threads("2..5C").as_deref(), None);
     }
 
+    #[test]
+    fn maven_profiles_combine_settings_and_tool_window_choices() {
+        let settings = MavenSettings { active_profiles: " a, b, ,a ".into(), ..Default::default() };
+        assert_eq!(settings.profiles(&["!b".into(), "c".into(), "a".into()]), ["a", "!b", "c"]);
+        let settings = MavenSettings { active_profiles: "!a".into(), ..Default::default() };
+        assert_eq!(settings.profiles(&["a".into()]), ["!a"]);
+    }
+
+    #[test]
+    fn maven_profiles_and_toolchains_round_trip_and_default_to_empty() {
+        let old: MavenSettings = serde_json::from_str(r#"{"home":"/opt/maven"}"#).unwrap();
+        assert!(old.toolchains.is_empty() && old.active_profiles.is_empty());
+        let settings =
+            MavenSettings { toolchains: "config files/toolchains.xml".into(), active_profiles: "a,b,!c".into(), ..old };
+        let encoded = serde_json::to_string(&settings).unwrap();
+        assert_eq!(serde_json::from_str::<MavenSettings>(&encoded).unwrap(), settings);
+    }
+
     #[test]
     fn thread_count_round_trips_and_defaults_to_empty() {
         // Old settings files predate the thread count; `serde(default)` keeps them loadable.

crates/ide-dap/src/adapter.rs

@@ -101,6 +101,7 @@ fn builtin(adapter: &str) -> Option<DebuggerConfig> {
         "lldb-dap" => {
             cfg("lldb-dap", &[], "stdio", "Install LLVM's lldb-dap (brew install llvm; on macOS `xcrun -f lldb-dap`)")
         }
+        "rdbg" => cfg("rdbg", &["-O", "--port", PORT_PLACEHOLDER, "-c"], "tcp", "gem install debug"),
         // A jdtls bundle: the session is started through jdtls and reached via `debugServer`.
         "java-debug" => cfg(
             "com.microsoft.java.debug.plugin.jar",

crates/ide-dap/src/lib.rs

@@ -305,6 +305,51 @@ pub struct DebugManager {
     stopping: Mutex<HashMap<DebugSessionId, Arc<Session>>>,
 }
 
+/// rdbg (Ruby's debug gem) starts the debuggee itself and ignores `launch`'s program,
+/// arguments and environment: they go on its command line after `--` and into its process.
+/// In a Bundler project it runs from the bundle, which must have `debug`: the debuggee then
+/// loads that version, and the gems rdbg needs (irb is not a default gem from Ruby 3.5).
+fn rdbg_command_line(spec: &mut AdapterSpec, config: &LaunchConfig, cwd: &Path) -> IdeResult<()> {
+    if spec.command == "rdbg"
+        && let Some(gemfile) = bundler_gemfile(cwd, &config.env)
+    {
+        if !bundles_debug(&gemfile) {
+            return Err(IdeError::unavailable(format!(
+                "the bundle of {} has no `debug` gem. Add `gem \"debug\"` to the Gemfile and run `bundle install`",
+                gemfile.display()
+            )));
+        }
+        spec.args.splice(0..0, ["exec".to_owned(), "rdbg".to_owned()]);
+        spec.command = "bundle".into();
+    }
+    spec.env.extend(config.env.iter().map(|(k, v)| (k.clone(), v.clone())));
+    spec.args.push("--".into());
+    spec.args.extend(config.program.iter().cloned());
+    spec.args.extend(config.args.iter().cloned());
+    Ok(())
+}
+
+/// The Gemfile Bundler uses in `dir`: `BUNDLE_GEMFILE`, else the closest `Gemfile` / `gems.rb` from `dir` up.
+fn bundler_gemfile(dir: &Path, env: &BTreeMap<String, String>) -> Option<PathBuf> {
+    match env.get("BUNDLE_GEMFILE").filter(|g| !g.is_empty()) {
+        Some(gemfile) => Some(dir.join(gemfile)),
+        None => dir.ancestors().flat_map(|d| [d.join("Gemfile"), d.join("gems.rb")]).find(|g| g.is_file()),
+    }
+}
+
+/// Whether the lockfile of `gemfile` lists the `debug` gem.
+fn bundles_debug(gemfile: &Path) -> bool {
+    let lockfile = if gemfile.file_name().is_some_and(|n| n == "gems.rb") {
+        gemfile.with_file_name("gems.locked")
+    } else {
+        let mut name = gemfile.as_os_str().to_owned();
+        name.push(".lock");
+        PathBuf::from(name)
+    };
+    // The bundle's gems are the lines indented by four spaces: `    debug (1.9.2)`.
+    std::fs::read_to_string(lockfile).is_ok_and(|text| text.lines().any(|l| l.starts_with("    debug (")))
+}
+
 /// Whether the debugged project depends on the Flutter SDK, so it must go
 /// through `flutter debug_adapter` instead of the plain Dart one.
 ///
@@ -651,6 +696,9 @@ impl DebugManager {
         {
             spec.env.push(("JAVA_HOME".into(), home));
         }
+        if config.adapter == "rdbg" {
+            rdbg_command_line(&mut spec, &config, &cwd)?;
+        }
         if let Some(command) = custom_command(&spec.command) {
             spec.command = command;
         }

crates/ide-dap/src/tests.rs

@@ -1391,6 +1391,71 @@ fn flutter_projects_are_found_from_the_program_or_the_working_directory() {
     std::fs::remove_dir_all(&root).unwrap();
 }
 
+#[test]
+fn rdbg_runs_the_debuggee_after_its_options_with_the_configuration_environment() {
+    let dir = tempfile::tempdir().unwrap();
+    let rdbg = adapter::find_config(&LanguageRegistry::from_configs(Vec::new()), "rdbg").unwrap();
+    let config = LaunchConfig {
+        adapter: "rdbg".into(),
+        program: Some("ruby".into()),
+        args: ["-Ilib", "app.rb", "--verbose"].map(String::from).to_vec(),
+        env: BTreeMap::from([("RAILS_ENV".into(), "test".into())]),
+        extra_json: None,
+        ..config()
+    };
+    let mut spec = adapter::resolve(&rdbg, dir.path().into());
+    rdbg_command_line(&mut spec, &config, dir.path()).unwrap();
+    assert_eq!(spec.command, "rdbg");
+    assert_eq!(spec.args, ["-O", "--port", "${port}", "-c", "--", "ruby", "-Ilib", "app.rb", "--verbose"]);
+    assert!(spec.env.contains(&("RAILS_ENV".into(), "test".into())));
+}
+
+#[test]
+fn rdbg_runs_from_a_bundle_that_has_debug_and_refuses_one_without() {
+    let dir = tempfile::tempdir().unwrap();
+    let app = dir.path().join("app");
+    std::fs::create_dir_all(app.join("lib")).unwrap();
+    std::fs::write(app.join("Gemfile"), "source \"https://rubygems.org\"\n").unwrap();
+    // A dependency of another gem is not a gem of the bundle.
+    std::fs::write(app.join("Gemfile.lock"), "GEM\n  specs:\n    irb (1.14.0)\n      debug (>= 1)\n").unwrap();
+    let rdbg = adapter::find_config(&LanguageRegistry::from_configs(Vec::new()), "rdbg").unwrap();
+    let config = LaunchConfig {
+        adapter: "rdbg".into(),
+        program: Some("bundle".into()),
+        args: ["exec", "rspec"].map(String::from).to_vec(),
+        extra_json: None,
+        ..config()
+    };
+    let mut spec = adapter::resolve(&rdbg, app.clone());
+    let err = rdbg_command_line(&mut spec, &config, &app).unwrap_err();
+    assert!(err.message.contains("gem \"debug\""), "{}", err.message);
+
+    std::fs::write(app.join("Gemfile.lock"), "GEM\n  specs:\n    debug (1.9.2)\n      irb (~> 1.10)\n").unwrap();
+    // From a subdirectory too: Bundler finds the Gemfile above it.
+    for cwd in [app.clone(), app.join("lib")] {
+        let mut spec = adapter::resolve(&rdbg, cwd.clone());
+        rdbg_command_line(&mut spec, &config, &cwd).unwrap();
+        assert_eq!(spec.command, "bundle");
+        assert_eq!(spec.args, ["exec", "rdbg", "-O", "--port", "${port}", "-c", "--", "bundle", "exec", "rspec"]);
+    }
+}
+
+#[test]
+fn bundler_gemfile_and_lockfile_follow_bundle_gemfile_and_gems_rb() {
+    let dir = tempfile::tempdir().unwrap();
+    let root = dir.path();
+    std::fs::create_dir_all(root.join("gems")).unwrap();
+    let none = BTreeMap::new();
+    assert_eq!(bundler_gemfile(root, &none), None);
+    std::fs::write(root.join("gems/gems.rb"), "").unwrap();
+    std::fs::write(root.join("gems/gems.locked"), "GEM\n  specs:\n    debug (1.9.2)\n").unwrap();
+    let gems_rb = bundler_gemfile(&root.join("gems"), &none).unwrap();
+    assert_eq!(gems_rb, root.join("gems/gems.rb"));
+    assert!(bundles_debug(&gems_rb));
+    let env = BTreeMap::from([("BUNDLE_GEMFILE".into(), "gems/gems.rb".into())]);
+    assert_eq!(bundler_gemfile(root, &env), Some(gems_rb));
+}
+
 #[cfg(unix)]
 #[tokio::test]
 async fn stop_waits_for_the_launched_program_to_exit() {

crates/ide-host/Cargo.toml

@@ -12,9 +12,12 @@ path = "src/bin/server.rs"
 [dependencies]
 encoding_rs.workspace = true
 ide-core.workspace = true
+ide-mcp.workspace = true
+futures.workspace = true
 ide-text.workspace = true
 ide-vfs.workspace = true
 regex-syntax.workspace = true
+regex-lite = "0.1"
 ide-workspace.workspace = true
 ide-language.workspace = true
 blake3.workspace = true

crates/ide-host/src/lib.rs

@@ -8,6 +8,7 @@ pub mod environment;
 mod formatter;
 mod java_runtime;
 mod kotlin_bridge;
+pub mod mcp;
 pub mod notebook;
 pub mod ops;
 mod phpstan;
@@ -54,6 +55,8 @@ pub struct HostConfig {
 }
 
 pub struct Host {
+    pub mcp_reports: mcp::Reports,
+    pub mcp_requests: mcp::Requests,
     pub trust: trust::TrustStore,
     pub config_dir: PathBuf,
     /// Persistent user state, including credentials and recovery history.
@@ -112,6 +115,8 @@ impl Host {
         let ssh = Arc::new(ide_ssh::SshManager::new(data_dir.join("ssh-passwords.json")));
         ssh.set_configs(global_settings.effective().ssh.configs);
         let host = Self {
+            mcp_reports: Default::default(),
+            mcp_requests: Default::default(),
             trust: trust::TrustStore::load(&config_dir, &data_dir),
             proxy_password: ide_ssh::secrets::SecretFile::new(data_dir.join("proxy-password.json")),
             proxy_session_password: Mutex::default(),
@@ -219,6 +224,8 @@ impl Host {
     /// so the window can open another project at once. Returns the thread that
     /// finishes shutting down its workers.
     fn begin_close(&self, window: &str) -> Option<std::thread::JoinHandle<()>> {
+        self.mcp_reports.forget_window(window);
+        self.mcp_requests.forget_window(window);
         self.external_logs.write().remove(self.owner_window(window));
         for request in self.project_requests.write().remove(self.owner_window(window)).unwrap_or_default() {
             self.cancel_request(request);

crates/ide-host/src/mcp/edit.rs

@@ -0,0 +1,448 @@
+// Ported from JetBrains intellij-community plugins/mcp-server (mcpserver.toolsets/src/general/PatchToolset.kt, FileToolset.kt), Apache-2.0.
+//! Changing the project and the editor: new files, patches, formatting and imports,
+//! rename, open editors.
+//!
+//! Text changes go through the document layer: an open editor's buffer is
+//! patched in place and remains unsaved. Other files are opened transiently,
+//! saved and closed. Saves record Local History like the IDE's own edits.
+
+mod diff;
+mod format;
+mod patch;
+mod rename;
+
+use crate::Project;
+use crate::mcp::tool::{Call, Output, Param, ParamType, Tool};
+use ide_core::event::McpUiRequest;
+use ide_core::{DocId, FileEdit, IdeError, IdeResult, Pos, Range, TextEdit, WorkspaceEdit};
+use patch::FileOp;
+use std::fmt::Write as _;
+use std::path::{Path, PathBuf};
+
+pub fn tools() -> Vec<Tool> {
+    vec![create_new_file(), apply_patch(), format::reformat_file(), rename::rename_refactoring(), open_file_in_editor()]
+}
+
+/// What tools without a result value answer (JetBrains renders `Unit` so).
+const SUCCESS: &str = "[success]";
+
+// --- the document layer ----------------------------------------------------------
+
+/// Whether the file is open with unsaved changes.
+fn is_dirty(project: &Project, path: &Path) -> bool {
+    project.documents.by_path(path).is_some_and(|d| project.documents.is_dirty(d).unwrap_or(false))
+}
+
+async fn create_or_replace(call: &Call, path: PathBuf, text: Option<String>, overwrite: bool) -> IdeResult<()> {
+    let project = call.project.clone();
+    let edit = call
+        .host
+        .blocking(move || {
+            let mut files = Vec::new();
+            if path.exists() {
+                if !overwrite {
+                    return Err(IdeError::invalid("File already exists"));
+                }
+                if let Some(text) = text {
+                    let info = project.documents.open(&path)?;
+                    let result: IdeResult<()> = (|| {
+                        let snap = project.documents.text_snapshot(info.id)?;
+                        let doc = ide_text::Document::new(&snap.text);
+                        let edits = doc
+                            .diff(&text)
+                            .changes
+                            .into_iter()
+                            .map(|c| TextEdit {
+                                range: Range::new(doc.offset_to_pos(c.from), doc.offset_to_pos(c.to)),
+                                new_text: c.insert,
+                            })
+                            .collect();
+                        files.push(FileEdit::Edit {
+                            path: path.into(),
+                            edits,
+                            version: Some(
+                                i32::try_from(snap.version)
+                                    .map_err(|_| IdeError::invalid("document version is out of range"))?,
+                            ),
+                        });
+                        Ok(())
+                    })();
+                    project.documents.close(info.id);
+                    result?;
+                }
+            } else {
+                files.push(FileEdit::Create { path: path.clone().into(), overwrite: false });
+                if let Some(text) = text {
+                    files.push(FileEdit::Edit {
+                        path: path.into(),
+                        edits: vec![TextEdit { range: Range::point(Pos::new(0, 0)), new_text: text }],
+                        version: None,
+                    });
+                }
+            }
+            Ok(WorkspaceEdit { files, preconditions: Vec::new() })
+        })
+        .await?;
+    if edit.files.is_empty() {
+        return Ok(());
+    }
+    let edit = crate::ops::lsp::prepare_workspace_edit(&call.host, call.window(), edit).await?;
+    crate::ops::lsp::apply_workspace_edit(&call.host, call.window(), edit).await
+}
+
+/// The open document of `path`, or a transient one (`true`: close it after use).
+fn open_document(project: &Project, path: &Path) -> IdeResult<(DocId, bool)> {
+    match project.documents.by_path(path) {
+        Some(doc) => Ok((doc, false)),
+        None => Ok((project.documents.open(path)?.id, true)),
+    }
+}
+
+fn normalize_newlines(text: &str) -> String {
+    text.replace("\r\n", "\n").replace('\r', "\n")
+}
+
+/// The range of a whole text.
+fn whole_range(text: &str) -> Range {
+    let count = text.split('\n').count();
+    let last = text.rsplit('\n').next().unwrap_or("");
+    Range::new(Pos::new(0, 0), Pos::new(count.saturating_sub(1) as u32, last.encode_utf16().count() as u32))
+}
+
+/// Whether two paths name the same file (language servers report canonical paths; on a
+/// case-insensitive file system `a.txt` and `A.txt` are one file).
+fn same_file(a: &Path, b: &Path) -> bool {
+    if a == b || matches!((dunce::canonicalize(a), dunce::canonicalize(b)), (Ok(x), Ok(y)) if x == y) {
+        return true;
+    }
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::MetadataExt;
+        if let (Ok(x), Ok(y)) = (std::fs::metadata(a), std::fs::metadata(b)) {
+            return x.dev() == y.dev() && x.ino() == y.ino();
+        }
+    }
+    false
+}
+
+/// The text edits of `edit` for `path`.
+fn edits_for(edit: &WorkspaceEdit, path: &Path) -> Vec<TextEdit> {
+    edit.files
+        .iter()
+        .filter_map(|f| match f {
+            ide_core::FileEdit::Edit { path: p, edits, .. } if same_file(p, path) => Some(edits.clone()),
+            _ => None,
+        })
+        .flatten()
+        .collect()
+}
+
+/// Re-reads the open, unmodified documents of `paths` whose files changed on disk, before
+/// a tool reads or changes them: an agent that just wrote a file itself must not have
+/// that write undone from a stale buffer because the file watcher has not caught up yet
+/// (JetBrains refreshes the VFS first). Documents with unsaved changes are left alone.
+fn refresh_from_disk(project: &Project, paths: &[PathBuf]) {
+    project.documents.on_disk_changed(paths);
+}
+
+/// Project files a tool works on: `files` resolved inside the project, existing,
+/// regular, without duplicates (the first spelling is kept), changeable
+/// ([`Call::check_writable`]) and with their open documents up to date with the disk.
+async fn requested_files(call: &Call) -> IdeResult<Vec<(String, PathBuf)>> {
+    let files = call.str_list("files")?;
+    if files.is_empty() {
+        return Err(IdeError::invalid("files must contain at least one path"));
+    }
+    let mut out: Vec<(String, PathBuf)> = Vec::new();
+    for raw in files {
+        let raw = raw.trim();
+        if raw.is_empty() {
+            return Err(IdeError::invalid("files must not contain blank paths"));
+        }
+        let path = call.resolve_inside(raw)?;
+        if !path.exists() {
+            return Err(IdeError::not_found(format!("File not found: {raw}")));
+        }
+        if !path.is_file() {
+            return Err(IdeError::invalid(format!("Not a file: {raw}")));
+        }
+        if !out.iter().any(|(_, p)| *p == path) {
+            out.push((raw.to_owned(), path));
+        }
+    }
+    for (_, path) in &out {
+        call.check_writable(path).await?;
+    }
+    let (project, paths) = (call.project().clone(), out.iter().map(|(_, p)| p.clone()).collect::<Vec<_>>());
+    call.host()
+        .blocking(move || {
+            refresh_from_disk(&project, &paths);
+            Ok(())
+        })
+        .await?;
+    Ok(out)
+}
+
+// --- create_new_file ----------------------------------------------------------------
+
+fn create_new_file() -> Tool {
+    Tool::new(
+        "create_new_file",
+        "Creates a new file at the specified path within the project directory and optionally populates it with \
+text if provided.
+Use this tool to generate new files in your project structure.
+Note: Creates any necessary parent directories automatically",
+        |call| async move {
+            let raw = call.str("pathInProject")?;
+            let path = call.resolve_writable(&raw).await?;
+            let text = call.opt_str("text")?.map(|t| normalize_newlines(&t));
+            let overwrite = call.flag("overwrite", false)?;
+            let cannot =
+                |e: &dyn std::fmt::Display| IdeError::invalid(format!("Can't create file: {}: {e}", path.display()));
+            if path.is_dir() {
+                return Err(cannot(&"it is a directory"));
+            }
+            if path.exists() && !overwrite {
+                return Err(IdeError::new(
+                    ide_core::error::ErrorKind::AlreadyExists,
+                    format!("File already exists: {raw}. Specify 'overwrite=true' to overwrite it"),
+                ));
+            }
+            create_or_replace(&call, path, text, overwrite).await?;
+            Ok(Output::text(SUCCESS))
+        },
+    )
+    .write()
+    .param(Param::required(
+        "pathInProject",
+        ParamType::String,
+        "Path where the file should be created relative to the project root",
+    ))
+    .param(Param::optional("text", ParamType::String, "Content to write into the new file"))
+    .param(Param::optional(
+        "overwrite",
+        ParamType::Boolean,
+        "Whether to overwrite an existing file if exists. If false, an exception is thrown in case of a conflict.",
+    ))
+}
+
+// --- apply_patch --------------------------------------------------------------------
+
+fn apply_patch() -> Tool {
+    Tool::new(
+        "apply_patch",
+        "Apply a patch using the Codex apply_patch format or unified git diff format.
+Supports Add, Delete, and Update operations with optional Move to path for updates.
+Paths must stay inside the project directory.",
+        |call| async move {
+            let input = [call.opt_str("input")?, call.opt_str("patch")?]
+                .into_iter()
+                .flatten()
+                .find(|s| !s.trim().is_empty())
+                .ok_or_else(|| IdeError::invalid("input must be a non-empty string"))?;
+            let ops = patch::parse(&input).map_err(IdeError::invalid)?;
+            let total = ops.iter().filter(|op| !matches!(op, FileOp::Skip { .. })).count();
+            let mut applied = 0usize;
+            let mut errors = Vec::new();
+            let mut notes = Vec::new();
+            // Each operation stands alone, as in JetBrains: a failed one leaves the others applied.
+            for op in ops {
+                if let FileOp::Skip { path, note } = op {
+                    notes.push(format!("{path}: {note}"));
+                    continue;
+                }
+                let path = op.path().to_owned();
+                match apply_op(&call, op, &mut notes).await {
+                    Ok(()) => applied += 1,
+                    Err(e) if e.kind == ide_core::error::ErrorKind::Cancelled => return Err(e),
+                    Err(e) => errors.push(format!("{path}: {}", e.message)),
+                }
+            }
+            let mut out = format!("{applied} out of {total} operations applied.");
+            if !errors.is_empty() {
+                let _ = write!(
+                    out,
+                    " {} operations failed to be applied due to errors:\n{}",
+                    errors.len(),
+                    errors.join("\n")
+                );
+            }
+            if !notes.is_empty() {
+                out.push_str("\nNotes:");
+                for n in notes {
+                    let _ = write!(out, "\n- {n}");
+                }
+            }
+            Ok(Output::text(out))
+        },
+    )
+    .write()
+    .param(Param::optional(
+        "input",
+        ParamType::String,
+        "Patch text in the apply_patch format or unified git diff format.",
+    ))
+    .param(Param::optional(
+        "patch",
+        ParamType::String,
+        "Alias of `input` for compatibility with clients that send `{patch: ...}`.",
+    ))
+}
+
+/// Applies one operation of a patch; its checks come first, so a failed operation changes nothing.
+async fn apply_op(call: &Call, op: FileOp, notes: &mut Vec<String>) -> IdeResult<()> {
+    let host = call.host();
+    let project = call.project().clone();
+    match op {
+        // Noted by the caller.
+        FileOp::Skip { .. } => Ok(()),
+        FileOp::Add { path: raw, text } => {
+            let path = call.resolve_writable(&raw).await?;
+            if path.exists() {
+                return Err(IdeError::invalid(format!("File already exists: {raw}")));
+            }
+            create_or_replace(call, path, Some(text), false).await
+        }
+        FileOp::Delete { path: raw } => {
+            let path = call.resolve_writable(&raw).await?;
+            if !path.is_file() {
+                return Err(IdeError::not_found(format!("File not found: {raw}")));
+            }
+            if is_dirty(&project, &path) {
+                return Err(IdeError::invalid("cannot delete a file with unsaved editor changes"));
+            }
+            let edit = WorkspaceEdit {
+                files: vec![FileEdit::Delete { path: path.into(), recursive: false }],
+                preconditions: Vec::new(),
+            };
+            let edit = crate::ops::lsp::prepare_workspace_edit(&host, call.window(), edit).await?;
+            crate::ops::lsp::apply_workspace_edit(&host, call.window(), edit).await
+        }
+        FileOp::Update { path: first, move_to, hunks, or } => {
+            // A plain diff's other names count when its `+++` path does not exist.
+            let mut raw = first.clone();
+            let mut path = call.resolve_inside(&raw)?;
+            for other in &or {
+                if path.exists() {
+                    break;
+                }
+                let candidate = call.resolve_inside(other)?;
+                if candidate.exists() {
+                    (raw, path) = (other.clone(), candidate);
+                }
+            }
+            if !path.exists() {
+                let tried = if or.is_empty() { String::new() } else { format!(" (also tried {})", or.join(", ")) };
+                return Err(IdeError::not_found(format!("File not found: {first}{tried}")));
+            }
+            if !path.is_file() {
+                return Err(IdeError::invalid(format!("Path is not a file: {raw}")));
+            }
+            if !hunks.is_empty() || move_to.is_some() {
+                call.check_writable(&path).await?;
+            }
+            let to = match &move_to {
+                Some(m) => {
+                    let to = call.resolve_writable(m).await?;
+                    // A move that changes only the case on a case-insensitive file system finds itself.
+                    if to != path && to.exists() && !same_file(&to, &path) {
+                        return Err(IdeError::new(
+                            ide_core::error::ErrorKind::AlreadyExists,
+                            format!("File already exists: {m}"),
+                        ));
+                    }
+                    Some(to).filter(|t| *t != path)
+                }
+                None => None,
+            };
+            let shown = call.display(&path);
+            let (p, target) = (project.clone(), path.clone());
+            let (mut edit, fuzzy, dirty) = host
+                .blocking(move || {
+                    refresh_from_disk(&p, std::slice::from_ref(&target));
+                    let info = p.documents.open(&target)?;
+                    let result = (|| {
+                        let snap = p.documents.text_snapshot(info.id)?;
+                        let dirty = p.documents.is_dirty(info.id)?;
+                        let applied = patch::apply(&snap.text, &hunks).map_err(IdeError::invalid)?;
+                        let text = ide_text::Document::new(&snap.text);
+                        let edits = text
+                            .diff(&applied.text)
+                            .changes
+                            .into_iter()
+                            .map(|c| TextEdit {
+                                range: Range::new(text.offset_to_pos(c.from), text.offset_to_pos(c.to)),
+                                new_text: c.insert,
+                            })
+                            .collect();
+                        Ok((
+                            WorkspaceEdit {
+                                files: vec![FileEdit::Edit {
+                                    path: target.clone().into(),
+                                    edits,
+                                    version: Some(
+                                        i32::try_from(snap.version)
+                                            .map_err(|_| IdeError::invalid("document version is out of range"))?,
+                                    ),
+                                }],
+                                preconditions: Vec::new(),
+                            },
+                            applied.fuzzy,
+                            dirty,
+                        ))
+                    })();
+                    p.documents.close(info.id);
+                    result
+                })
+                .await?;
+            if let Some(to) = to {
+                edit.files.push(FileEdit::Rename { from: path.into(), to: to.into() });
+            }
+            let edit = crate::ops::lsp::prepare_workspace_edit(&host, call.window(), edit).await?;
+            crate::ops::lsp::apply_workspace_edit(&host, call.window(), edit).await?;
+            if dirty {
+                notes.push(format!("{shown}: patched the unsaved editor buffer"));
+            }
+            for (hunk, fuzz) in fuzzy {
+                notes.push(format!("{shown}: hunk {hunk} matched only {}", fuzz.describe()));
+            }
+            Ok(())
+        }
+    }
+}
+
+// --- the editor ------------------------------------------------------------------------
+
+fn open_file_in_editor() -> Tool {
+    Tool::new(
+        "open_file_in_editor",
+        "Opens the specified file in the IDE editor.
+Requires a filePath parameter containing the path to the file to open.
+The file path can be absolute or relative to the project root.
+Optionally puts the caret at a 1-based line and column.",
+        |call| async move {
+            let raw = call.str("filePath")?;
+            // Opening shows the file to the user: outside the project the user agrees first.
+            let path = call.resolve_readable(&raw).await?;
+            if !path.is_file() {
+                return Err(IdeError::not_found(format!("File {raw} doesn't exist or can't be opened")));
+            }
+            let positive = |name: &str| -> IdeResult<Option<u32>> {
+                match call.opt_i64(name)? {
+                    None => Ok(None),
+                    Some(n) if n < 1 || n > u32::MAX as i64 => {
+                        Err(IdeError::invalid(format!("`{name}` is 1-based and must be at least 1")))
+                    }
+                    Some(n) => Ok(Some(n as u32)),
+                }
+            };
+            let (line, column) = (positive("line")?, positive("column")?);
+            call.ask(McpUiRequest::OpenFile { path: path.into(), line, column }).await?;
+            Ok(Output::text(SUCCESS))
+        },
+    )
+    .write()
+    .param(Param::required("filePath", ParamType::String, "Path relative to the project root"))
+    .param(Param::optional("line", ParamType::Integer, "1-based line to put the caret on"))
+    .param(Param::optional("column", ParamType::Integer, "1-based column on that line"))
+}

crates/ide-host/src/mcp/edit/diff.rs

@@ -0,0 +1,380 @@
+// Ported from JetBrains intellij-community plugins/mcp-server (mcpserver.toolsets/src/general/UnifiedDiffSupport.kt), Apache-2.0.
+//! The unified diff tools answer with, so an agent sees what the IDE changed
+//! without reading the files again. Capped, so a large change cannot flood the
+//! agent's context.
+
+/// Unchanged lines kept around each change, as in a standard unified diff.
+const CONTEXT_LINES: usize = 3;
+
+/// The default cap on diff lines.
+pub const MAX_DIFF_LINES: usize = 200;
+
+/// The smallest useful hunk: the `@@` header line and one line under it.
+const MIN_HUNK_LINES: usize = 2;
+
+/// Beyond this many differing lines (after the common head and tail) the
+/// diff is not computed: the file is reported as too large to diff.
+const MAX_EDIT_DISTANCE: usize = 2000;
+
+/// One file a tool processed: the requested path, the text before and after.
+/// `None` texts are reported as unavailable, never as "nothing changed".
+pub struct ChangedFileText {
+    pub path: String,
+    pub before: Option<String>,
+    pub after: Option<String>,
+}
+
+/// A unified diff of the changes in `files`, at most `max_lines` diff lines;
+/// `None` when nothing changed. A file goes in whole, or the footer names it.
+pub fn build_unified_diff(files: &[ChangedFileText], max_lines: usize) -> Option<String> {
+    let mut lines: Vec<String> = Vec::new();
+    let mut omitted_files = Vec::new();
+    let mut omitted_lines = 0usize;
+    for file in files {
+        let Some(diff) = file_diff(file) else { continue };
+        // A header with no hunk under it helps nobody.
+        if !lines.is_empty() && max_lines.saturating_sub(lines.len()) < diff.header.len() + MIN_HUNK_LINES {
+            omitted_files.push(diff.path.clone());
+            omitted_lines += diff.line_count();
+            continue;
+        }
+        lines.extend(diff.header.iter().cloned());
+        for (index, hunk) in diff.hunks.iter().enumerate() {
+            let room = max_lines as isize - lines.len() as isize - 1;
+            if room < 1 && index > 0 {
+                omitted_lines += diff.hunks[index..].iter().map(Hunk::line_count).sum::<usize>();
+                break;
+            }
+            // The first hunk always keeps one line, so its file header never stands alone.
+            let body = room.max(1) as usize;
+            lines.extend(hunk.render(body));
+            omitted_lines += hunk.body.len().saturating_sub(body);
+        }
+    }
+    if lines.is_empty() {
+        return None;
+    }
+    let mut out = lines.join("\n");
+    if omitted_lines > 0 {
+        out.push_str(&format!("\n… and {omitted_lines} more diff line(s) omitted."));
+    }
+    if !omitted_files.is_empty() {
+        out.push_str(&format!("\n… The diff leaves out these file(s): {}.", omitted_files.join(", ")));
+    }
+    Some(out)
+}
+
+struct FileDiff {
+    path: String,
+    header: Vec<String>,
+    hunks: Vec<Hunk>,
+}
+
+impl FileDiff {
+    fn line_count(&self) -> usize {
+        self.header.len() + self.hunks.iter().map(Hunk::line_count).sum::<usize>()
+    }
+}
+
+/// One hunk: where it starts on each side (0-based), and its `-`, `+` and context lines.
+struct Hunk {
+    start0: usize,
+    start1: usize,
+    body: Vec<String>,
+}
+
+impl Hunk {
+    fn line_count(&self) -> usize {
+        self.body.len() + 1
+    }
+
+    /// The hunk with at most `max_body` body lines; the header counts the lines it prints.
+    fn render(&self, max_body: usize) -> Vec<String> {
+        let printed = &self.body[..self.body.len().min(max_body)];
+        let count0 = printed.iter().filter(|l| l.starts_with(' ') || l.starts_with('-')).count();
+        let count1 = printed.iter().filter(|l| l.starts_with(' ') || l.starts_with('+')).count();
+        // An empty range names the line before it, so it keeps the 0-based value.
+        let start = |s: usize, count: usize| if count == 0 { s } else { s + 1 };
+        let mut out =
+            vec![format!("@@ -{},{count0} +{},{count1} @@", start(self.start0, count0), start(self.start1, count1))];
+        out.extend(printed.iter().cloned());
+        out
+    }
+}
+
+/// A line of the text, and whether it ends without a line separator (the last line).
+type DiffLine<'a> = (&'a str, bool);
+
+fn file_diff(file: &ChangedFileText) -> Option<FileDiff> {
+    let path = file.path.replace('\\', "/");
+    let header = vec![format!("--- a/{path}"), format!("+++ b/{path}")];
+    let note = |text: &str| {
+        let mut header = header.clone();
+        header.push(format!("({text})"));
+        Some(FileDiff { path: path.clone(), header, hunks: Vec::new() })
+    };
+    let (Some(before), Some(after)) = (&file.before, &file.after) else {
+        return note(
+            "the content of this file is not available, so the diff cannot report what changed; read the file again",
+        );
+    };
+    if before == after {
+        return None;
+    }
+    let old = split_lines(before);
+    let new = split_lines(after);
+    let Some(changes) = changes(&old, &new) else { return note("this file changed, but it is too large to diff") };
+    // The texts differ but the lines are equal: only the line separators changed.
+    if changes.is_empty() {
+        return note("only the line separators of this file changed");
+    }
+    let hunks = group(&changes).into_iter().map(|g| build_hunk(g, &old, &new)).collect();
+    Some(FileDiff { path, header, hunks })
+}
+
+/// The lines a diff compares: no extra empty line after a final separator; a
+/// last line without one is marked, so a change of the final separator alone counts.
+fn split_lines(text: &str) -> Vec<DiffLine<'_>> {
+    if text.is_empty() {
+        return Vec::new();
+    }
+    let ends_with_newline = text.ends_with('\n');
+    let mut lines: Vec<DiffLine> = text.split('\n').map(|l| (l.strip_suffix('\r').unwrap_or(l), false)).collect();
+    if ends_with_newline {
+        lines.pop();
+    } else if let Some(last) = lines.last_mut() {
+        last.1 = true;
+    }
+    lines
+}
+
+/// A run of changed lines: at `line0` in the old text `deleted` lines, at `line1` in the new one `inserted`.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+struct Change {
+    line0: usize,
+    line1: usize,
+    deleted: usize,
+    inserted: usize,
+}
+
+/// The changes from `a` to `b` (Myers' algorithm), `None` when they differ too much.
+fn changes(a: &[DiffLine], b: &[DiffLine]) -> Option<Vec<Change>> {
+    let head = a.iter().zip(b).take_while(|(x, y)| x == y).count();
+    let tail = a[head..].iter().rev().zip(b[head..].iter().rev()).take_while(|(x, y)| x == y).count();
+    let (a_mid, b_mid) = (&a[head..a.len() - tail], &b[head..b.len() - tail]);
+    let script = myers(a_mid, b_mid)?;
+    // `script`: per step, true = equal (both advance), Some side otherwise.
+    let mut out: Vec<Change> = Vec::new();
+    let (mut i, mut j) = (head, head);
+    for step in script {
+        match step {
+            Step::Equal => {
+                i += 1;
+                j += 1;
+                continue;
+            }
+            Step::Delete => {
+                match out.last_mut() {
+                    Some(c) if c.line0 + c.deleted == i && c.line1 + c.inserted == j => c.deleted += 1,
+                    _ => out.push(Change { line0: i, line1: j, deleted: 1, inserted: 0 }),
+                }
+                i += 1;
+            }
+            Step::Insert => {
+                match out.last_mut() {
+                    Some(c) if c.line0 + c.deleted == i && c.line1 + c.inserted == j => c.inserted += 1,
+                    _ => out.push(Change { line0: i, line1: j, deleted: 0, inserted: 1 }),
+                }
+                j += 1;
+            }
+        }
+    }
+    Some(out)
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+enum Step {
+    Equal,
+    Delete,
+    Insert,
+}
+
+/// The shortest edit script from `a` to `b`, deletions before insertions in each run.
+fn myers(a: &[DiffLine], b: &[DiffLine]) -> Option<Vec<Step>> {
+    let (n, m) = (a.len() as isize, b.len() as isize);
+    let max = (n + m) as usize;
+    let limit = max.min(MAX_EDIT_DISTANCE) as isize;
+    let off = max as isize + 1;
+    let mut v = vec![0isize; 2 * max + 3];
+    // V after each round d, for diagonals -d..=d.
+    let mut trace: Vec<Vec<isize>> = Vec::new();
+    let mut end = None;
+    'rounds: for d in 0..=limit {
+        for k in (-d..=d).step_by(2) {
+            let at = |k: isize| (off + k) as usize;
+            let mut x =
+                if k == -d || (k != d && v[at(k - 1)] < v[at(k + 1)]) { v[at(k + 1)] } else { v[at(k - 1)] + 1 };
+            let mut y = x - k;
+            while x < n && y < m && a[x as usize] == b[y as usize] {
+                x += 1;
+                y += 1;
+            }
+            v[at(k)] = x;
+            if x >= n && y >= m {
+                trace.push(v[at(-d)..=at(d)].to_vec());
+                end = Some(d);
+                break 'rounds;
+            }
+        }
+        trace.push(v[(off - d) as usize..=(off + d) as usize].to_vec());
+    }
+    let d_end = end?;
+    let mut steps = Vec::new();
+    let (mut x, mut y) = (n, m);
+    for d in (1..=d_end).rev() {
+        let prev = &trace[(d - 1) as usize];
+        let get = |k: isize| prev[(k + d - 1) as usize];
+        let k = x - y;
+        let insert = k == -d || (k != d && get(k - 1) < get(k + 1));
+        let prev_k = if insert { k + 1 } else { k - 1 };
+        let prev_x = get(prev_k);
+        let prev_y = prev_x - prev_k;
+        let (mid_x, mid_y) = if insert { (prev_x, prev_y + 1) } else { (prev_x + 1, prev_y) };
+        while x > mid_x && y > mid_y {
+            steps.push(Step::Equal);
+            x -= 1;
+            y -= 1;
+        }
+        steps.push(if insert { Step::Insert } else { Step::Delete });
+        (x, y) = (prev_x, prev_y);
+    }
+    steps.extend(std::iter::repeat_n(Step::Equal, x as usize));
+    steps.reverse();
+    // Within a run of changes, deletions first (as `-` lines precede `+` lines).
+    let mut i = 0;
+    while i < steps.len() {
+        if steps[i] == Step::Equal {
+            i += 1;
+            continue;
+        }
+        let end = steps[i..].iter().position(|s| *s == Step::Equal).map_or(steps.len(), |p| i + p);
+        steps[i..end].sort_by_key(|s| *s == Step::Insert);
+        i = end;
+    }
+    Some(steps)
+}
+
+/// Changes whose context lines touch share a hunk.
+fn group(changes: &[Change]) -> Vec<&[Change]> {
+    let mut out: Vec<&[Change]> = Vec::new();
+    let mut start = 0;
+    for i in 1..changes.len() {
+        let prev = changes[i - 1];
+        if changes[i].line0 - (prev.line0 + prev.deleted) > CONTEXT_LINES * 2 {
+            out.push(&changes[start..i]);
+            start = i;
+        }
+    }
+    if !changes.is_empty() {
+        out.push(&changes[start..]);
+    }
+    out
+}
+
+fn build_hunk(group: &[Change], old: &[DiffLine], new: &[DiffLine]) -> Hunk {
+    let (first, last) = (group[0], group[group.len() - 1]);
+    // One clamp for both sides, so the two starts in the header stay in step.
+    let leading = CONTEXT_LINES.min(first.line0).min(first.line1);
+    let (start0, start1) = (first.line0 - leading, first.line1 - leading);
+    let (end0, end1) = (last.line0 + last.deleted, last.line1 + last.inserted);
+    let trailing = CONTEXT_LINES.min(old.len() - end0).min(new.len() - end1);
+    let mut body = Vec::new();
+    let push = |body: &mut Vec<String>, prefix: char, (text, no_newline): DiffLine| {
+        body.push(format!("{prefix}{text}"));
+        if no_newline {
+            body.push("\\ No newline at end of file".into());
+        }
+    };
+    let mut line0 = start0;
+    for c in group {
+        while line0 < c.line0 {
+            push(&mut body, ' ', old[line0]);
+            line0 += 1;
+        }
+        for &l in &old[c.line0..c.line0 + c.deleted] {
+            push(&mut body, '-', l);
+        }
+        for &l in &new[c.line1..c.line1 + c.inserted] {
+            push(&mut body, '+', l);
+        }
+        line0 = c.line0 + c.deleted;
+    }
+    while line0 < end0 + trailing {
+        push(&mut body, ' ', old[line0]);
+        line0 += 1;
+    }
+    Hunk { start0, start1, body }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn diff(before: &str, after: &str) -> Option<String> {
+        build_unified_diff(
+            &[ChangedFileText { path: "src/A.java".into(), before: Some(before.into()), after: Some(after.into()) }],
+            MAX_DIFF_LINES,
+        )
+    }
+
+    #[test]
+    fn diffs_a_reformat_like_jetbrains() {
+        let out = diff("public class DiffTarget {\nint a;\n}\n", "public class DiffTarget {\n    int a;\n}\n").unwrap();
+        assert_eq!(
+            out,
+            "--- a/src/A.java\n+++ b/src/A.java\n@@ -1,3 +1,3 @@\n public class DiffTarget {\n-int a;\n+    int a;\n }"
+        );
+        assert_eq!(diff("same\n", "same\n"), None);
+    }
+
+    #[test]
+    fn splits_far_changes_into_hunks_and_marks_the_final_newline() {
+        let before: String = (1..=20).map(|i| format!("{i}\n")).collect();
+        let after: String = (1..=20)
+            .map(|i| match i {
+                2 => "two\n".to_owned(),
+                19 => "nineteen\n".to_owned(),
+                i => format!("{i}\n"),
+            })
+            .collect();
+        let out = diff(&before, &after).unwrap();
+        assert!(out.contains("@@ -1,5 +1,5 @@\n 1\n-2\n+two\n 3\n 4\n 5\n"), "{out}");
+        assert!(out.contains("@@ -16,5 +16,5 @@\n 16\n 17\n 18\n-19\n+nineteen\n 20"), "{out}");
+        let out = diff("a\nb", "a\nb\n").unwrap();
+        assert!(out.ends_with("@@ -1,2 +1,2 @@\n a\n-b\n\\ No newline at end of file\n+b"), "{out}");
+        let out = diff("a\r\n", "a\n").unwrap();
+        assert!(out.ends_with("(only the line separators of this file changed)"), "{out}");
+        let out = diff("", "x\n").unwrap();
+        assert!(out.ends_with("@@ -0,0 +1,1 @@\n+x"), "{out}");
+        let out = diff("import a;\n\nclass X {}\n", "\nclass X {}\n").unwrap();
+        assert!(out.ends_with("@@ -1,3 +1,2 @@\n-import a;\n \n class X {}"), "{out}");
+    }
+
+    #[test]
+    fn caps_the_diff_and_names_what_it_leaves_out() {
+        let before: String = (0..300).map(|i| format!("{i}\n")).collect();
+        let after: String = (0..300).map(|i| format!("x{i}\n")).collect();
+        let files = [
+            ChangedFileText { path: "a.txt".into(), before: Some(before.clone()), after: Some(after.clone()) },
+            ChangedFileText { path: "b.txt".into(), before: Some(before), after: Some(after) },
+            ChangedFileText { path: "c.bin".into(), before: None, after: None },
+        ];
+        let out = build_unified_diff(&files, 50).unwrap();
+        assert_eq!(out.lines().filter(|l| !l.starts_with('…')).count(), 50, "{out}");
+        // 553 lines of a.txt's hunk, 603 of b.txt, 3 of c.bin's note.
+        assert!(out.contains("… and 1159 more diff line(s) omitted."), "{out}");
+        assert!(out.ends_with("… The diff leaves out these file(s): b.txt, c.bin."), "{out}");
+        // The cut hunk's header counts what it prints.
+        assert!(out.contains("@@ -1,47 +0,0 @@"), "{out}");
+    }
+}

crates/ide-host/src/mcp/edit/format.rs

@@ -0,0 +1,199 @@
+// Ported from JetBrains intellij-community plugins/mcp-server (mcpserver.toolsets/src/general/FormattingToolset.kt), Apache-2.0.
+//! `reformat_file` and `optimize_imports` with the language servers: document
+//! formatting and the `source.organizeImports` code action. Both answer with a
+//! unified diff of what changed, or `ok`.
+//!
+//! JetBrains always has a formatter and an import optimizer; here a file whose
+//! language server offers none is reported after the diff (the whole call fails
+//! only when no file could be processed).
+
+use super::diff::{ChangedFileText, MAX_DIFF_LINES, build_unified_diff};
+use super::{edits_for, open_document, requested_files, whole_range};
+use crate::mcp::tool::{Call, Output, Param, ParamType, Tool};
+use ide_core::{DocId, IdeError, IdeResult};
+use std::path::Path;
+
+const ORGANIZE_IMPORTS: &str = "source.organizeImports";
+
+pub(super) fn reformat_file() -> Tool {
+    Tool::new(
+        "reformat_file",
+        "Reformats the specified files in the IDE.
+Use this tool to apply code formatting rules to files identified by their project-relative paths.
+Returns a unified diff of the changes that the formatter applied, or \"ok\" when the files already match the code \
+style.
+The diff shows the formatter changes only. It never repeats the edit that you applied yourself.
+The diff stops at 200 lines. A footer names the file(s) that it leaves out.
+To remove unused imports without reformatting, use optimize_imports.",
+        |call| async move {
+            let organize = call.flag("optimizeImports", false)?;
+            run(&call, Job { organize, format: true }).await
+        },
+    )
+    .write()
+    .param(Param::required(
+        "files",
+        ParamType::StringList,
+        "List of project-relative files to reformat. Duplicate paths are ignored after normalization.",
+    ))
+    .param(Param::optional(
+        "optimizeImports",
+        ParamType::Boolean,
+        "If true, also remove unused imports and order the remaining ones before reformatting.",
+    ))
+}
+
+#[derive(Clone, Copy)]
+struct Job {
+    organize: bool,
+    format: bool,
+}
+
+async fn run(call: &Call, job: Job) -> IdeResult<Output> {
+    let files = requested_files(call).await?;
+    let mut changed = Vec::new();
+    let mut problems = Vec::new();
+    for (raw, path) in &files {
+        match process(call, path, job).await {
+            Ok(outcome) => {
+                changed.push(ChangedFileText {
+                    path: raw.clone(),
+                    before: Some(outcome.before),
+                    after: Some(outcome.after),
+                });
+                problems.extend(outcome.notes.into_iter().map(|n| format!("{raw}: {n}")));
+            }
+            Err(e) if e.kind == ide_core::error::ErrorKind::Cancelled => return Err(e),
+            Err(e) => {
+                let what = if job.format { "not formatted" } else { "imports not optimized" };
+                problems.push(format!("{raw}: {what}: {}", e.message));
+            }
+        }
+    }
+    if changed.is_empty() {
+        return Err(IdeError::unavailable(problems.join("\n")));
+    }
+    let mut out = build_unified_diff(&changed, MAX_DIFF_LINES).unwrap_or_else(|| "ok".into());
+    if !problems.is_empty() {
+        out.push_str("\n\n");
+        out.push_str(&problems.join("\n"));
+    }
+    Ok(Output::text(out))
+}
+
+struct Outcome {
+    before: String,
+    after: String,
+    /// What went wrong without failing the file (imports not optimized before a reformat).
+    notes: Vec<String>,
+}
+
+/// Runs the job on one file's document (opened transiently when it is not open) and saves it.
+async fn process(call: &Call, path: &Path, job: Job) -> IdeResult<Outcome> {
+    let host = call.host();
+    let project = call.project().clone();
+    let (p, target) = (project.clone(), path.to_path_buf());
+    let (doc, transient) = host.blocking(move || open_document(&p, &target)).await?;
+    let result = async {
+        let info = project.documents.snapshot(doc)?;
+        if info.read_only {
+            return Err(IdeError::invalid("the file is read-only"));
+        }
+        let before = project.documents.text_snapshot(doc)?.text;
+        let mut notes = Vec::new();
+        if job.organize {
+            match organize_imports(call, doc, path).await {
+                Ok(()) => {}
+                Err(e) if job.format && e.kind != ide_core::error::ErrorKind::Cancelled => {
+                    notes.push(format!("imports not optimized: {}", e.message));
+                }
+                Err(e) => return Err(e),
+            }
+        }
+        if job.format {
+            format(call, doc, &info).await?;
+        }
+        let p = project.clone();
+        let after = host
+            .blocking(move || {
+                if !info.dirty && p.documents.is_dirty(doc)? {
+                    p.documents.save(doc)?;
+                }
+                Ok(p.documents.text_snapshot(doc)?.text)
+            })
+            .await?;
+        Ok(Outcome { before, after, notes })
+    }
+    .await;
+    if transient {
+        project.documents.close(doc);
+    }
+    result
+}
+
+/// Formats the whole document with its language server; indentation from EditorConfig, else the settings.
+async fn format(call: &Call, doc: DocId, info: &ide_workspace::DocumentInfo) -> IdeResult<()> {
+    let host = call.host();
+    let project = call.project().clone();
+    let editor = project.settings.effective().editor;
+    let ec = info.editorconfig.as_ref();
+    let insert_spaces = match ec.and_then(|e| e.indent_style) {
+        Some(style) => style != ide_workspace::editorconfig::IndentStyle::Tab,
+        None => editor.insert_spaces,
+    };
+    let tab_size = ec.and_then(|e| e.indent_size.or(e.tab_width)).unwrap_or(editor.tab_size);
+    let options = ide_lsp::types::FormatOptions { tab_size, insert_spaces, on_save: false, tool: None };
+    let version = project.documents.text_snapshot(doc)?.version;
+    let edits = tokio::select! {
+        r = crate::ops::lsp::lsp_format(&host, call.window(), doc, None, options) => r?,
+        _ = call.cancel.cancelled() => return Err(IdeError::cancelled()),
+    };
+    host.blocking(move || {
+        if project.documents.text_snapshot(doc)?.version != version {
+            return Err(IdeError::unavailable("the file changed while it was being formatted; try again"));
+        }
+        project.documents.apply_edits(doc, &edits).map(|_| ())
+    })
+    .await
+}
+
+/// Runs the `source.organizeImports` code action of the document's language server.
+/// Nothing offered: nothing to do, unless the server says it has no such action at all.
+pub(super) async fn organize_imports(call: &Call, doc: DocId, path: &Path) -> IdeResult<()> {
+    let host = call.host();
+    let window = call.window();
+    let text = call.project().documents.text_snapshot(doc)?.text;
+    let request = crate::mcp::tool::request_id();
+    let only = vec![ORGANIZE_IMPORTS.to_owned()];
+    let query = tokio::select! {
+        r = crate::ops::lsp::lsp_code_action_query(&host, window, request, doc, whole_range(&text), only) => r?,
+        _ = call.cancel.cancelled() => {
+            host.cancel_request(request);
+            return Err(IdeError::cancelled());
+        }
+    };
+    let organizes = |kind: &str| kind == ORGANIZE_IMPORTS || kind.starts_with("source.organizeImports.");
+    let action = query
+        .actions
+        .into_iter()
+        .filter(|a| a.disabled_reason.is_none() && a.kind.as_deref().is_some_and(organizes))
+        .max_by_key(|a| a.is_preferred);
+    let Some(action) = action else {
+        let offered = query.advertised_kinds.is_none_or(|kinds| kinds.iter().any(|k| k == "source" || organizes(k)));
+        return if offered {
+            Ok(())
+        } else {
+            Err(IdeError::unavailable("the language server of this file offers no organize imports action"))
+        };
+    };
+    let action = crate::ops::lsp::lsp_resolve_code_action(&host, window, doc, action).await?;
+    match &action.edit {
+        Some(edit) => {
+            let edits = edits_for(edit, path);
+            let project = call.project().clone();
+            host.blocking(move || project.documents.apply_edits(doc, &edits).map(|_| ())).await
+        }
+        // The server applies the change itself (`workspace/applyEdit` during the command).
+        None => crate::ops::lsp::lsp_apply_code_action(&host, window, doc, action).await,
+    }
+}

crates/ide-host/src/mcp/edit/patch.rs

@@ -0,0 +1,949 @@
+// Ported from JetBrains intellij-community plugins/mcp-server (mcpserver.toolsets/src/general/PatchApplyEngine.kt), Apache-2.0.
+//! Patches as AI agents write them: the Codex `apply_patch` format (with the
+//! strict `@@` pair blocks some models write) and unified (git) diffs, bare or
+//! inside `*** Begin Patch`. Parsing and applying hunks to a text are pure, so
+//! they are tested here; the tool in `edit.rs` resolves paths and writes through
+//! the documents.
+//!
+//! Beyond JetBrains: stacked `@@` anchors, unified hunk line numbers as hints,
+//! `\ No newline at end of file`, plain `diff -u` / `diff -ru` names, and errors
+//! that show where a hunk went wrong.
+
+use std::fmt::Write as _;
+
+/// One file of a patch, paths as written in it.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum FileOp {
+    Add {
+        path: String,
+        text: String,
+    },
+    Delete {
+        path: String,
+    },
+    /// `or` lists other paths the file may have, tried in order when `path` does
+    /// not exist (a plain diff's `---` name, or its names without their first
+    /// directory, as `patch -p1` reads `diff -ru old/ new/`).
+    Update {
+        path: String,
+        move_to: Option<String>,
+        hunks: Vec<Hunk>,
+        or: Vec<String>,
+    },
+    /// A git section the tool does not apply (a copy): skipped with `note`, the others go on.
+    Skip {
+        path: String,
+        note: String,
+    },
+}
+
+impl FileOp {
+    pub fn path(&self) -> &str {
+        match self {
+            FileOp::Add { path, .. }
+            | FileOp::Delete { path }
+            | FileOp::Update { path, .. }
+            | FileOp::Skip { path, .. } => path,
+        }
+    }
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub struct Hunk {
+    /// `@@ <line>` anchors: found in order before the hunk's lines.
+    pub anchors: Vec<String>,
+    /// `@@ -a,b +c,d @@`: the 1-based start in the old file, a hint where to look.
+    pub old_start: Option<usize>,
+    pub lines: Vec<Line>,
+    /// `*** End of File`: the lines end the file.
+    pub at_eof: bool,
+    /// `\ No newline at end of file` after the old / new side.
+    pub old_no_newline: bool,
+    pub new_no_newline: bool,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum Line {
+    Context(String),
+    Remove(String),
+    Add(String),
+}
+
+impl Hunk {
+    fn old_lines(&self) -> Vec<&str> {
+        self.lines
+            .iter()
+            .filter_map(|l| match l {
+                Line::Context(s) | Line::Remove(s) => Some(s.as_str()),
+                Line::Add(_) => None,
+            })
+            .collect()
+    }
+
+    fn new_lines(&self) -> Vec<&str> {
+        self.lines
+            .iter()
+            .filter_map(|l| match l {
+                Line::Context(s) | Line::Add(s) => Some(s.as_str()),
+                Line::Remove(_) => None,
+            })
+            .collect()
+    }
+
+    /// How the hunk is named in errors.
+    fn label(&self, n: usize) -> String {
+        match (self.anchors.last(), self.old_start) {
+            (Some(a), _) => format!("hunk {n} (@@ {a})"),
+            (None, Some(s)) => format!("hunk {n} (at line {s})"),
+            _ => format!("hunk {n}"),
+        }
+    }
+}
+
+const BEGIN_PATCH: &str = "*** Begin Patch";
+const END_PATCH: &str = "*** End Patch";
+const ADD: &str = "*** Add File: ";
+const DELETE: &str = "*** Delete File: ";
+const UPDATE: &str = "*** Update File: ";
+const MOVE: &str = "*** Move to: ";
+const END_OF_FILE: &str = "*** End of File";
+const DIFF_GIT: &str = "diff --git ";
+
+/// Parses either format: `*** Begin Patch` … `*** End Patch` (holding the Codex
+/// format or a git diff), else a bare unified diff.
+pub fn parse(input: &str) -> Result<Vec<FileOp>, String> {
+    let lines: Vec<&str> = input.split('\n').map(|l| l.strip_suffix('\r').unwrap_or(l)).collect();
+    let ops = match lines.iter().position(|l| l.trim() == BEGIN_PATCH) {
+        Some(begin) => {
+            let end = lines[begin + 1..]
+                .iter()
+                .position(|l| l.trim() == END_PATCH)
+                .map(|e| begin + 1 + e)
+                .ok_or("patch must include *** End Patch (the patch looks truncated)")?;
+            let body = &lines[begin + 1..end];
+            // `--- x` also removes a `-- x` line (SQL, Lua comments): only a body without
+            // Codex headers is read as a diff.
+            let codex = body.iter().any(|l| {
+                let t = l.trim_start();
+                t.starts_with(ADD) || t.starts_with(DELETE) || t.starts_with(UPDATE)
+            });
+            if !codex && looks_like_git_diff(body) {
+                parse_unified(body, begin + 1)?
+            } else {
+                parse_codex(body, begin + 1)?
+            }
+        }
+        None if looks_like_git_diff(&lines) => parse_unified(&lines, 0)?,
+        None => {
+            return Err("patch must include *** Begin Patch (or be a unified diff with `--- a/path` and \
+`+++ b/path` headers)"
+                .into());
+        }
+    };
+    if ops.is_empty() {
+        return Err("patch did not contain any operations".into());
+    }
+    Ok(ops)
+}
+
+fn looks_like_git_diff(lines: &[&str]) -> bool {
+    let mut markers = false;
+    for line in lines {
+        let t = line.trim_start();
+        if t.starts_with(DIFF_GIT) || t.starts_with("rename from ") || t.starts_with("rename to ") {
+            return true;
+        }
+        markers |= line.starts_with("--- ") || line.starts_with("+++ ");
+    }
+    markers
+}
+
+/// Refuses paths with control characters, or with `\n`-style escapes a model wrote
+/// instead of a real path.
+fn ensure_safe_path(path: &str, label: &str) -> Result<(), String> {
+    let control = path.chars().any(|c| c.is_ascii_control());
+    let escaped = ["\\n", "\\r", "\\t"].iter().any(|e| path.contains(e));
+    if control || escaped {
+        Err(format!("{label} path contains control characters or escape sequences"))
+    } else {
+        Ok(())
+    }
+}
+
+// --- the Codex format -----------------------------------------------------------
+
+fn is_diff_prefix(c: char) -> bool {
+    matches!(c, ' ' | '+' | '-')
+}
+
+/// `*** Add File:` and the like (not `*** End of File`, which belongs to a hunk).
+fn is_patch_header(line: &str) -> bool {
+    match line.chars().next() {
+        None => false,
+        Some(c) if is_diff_prefix(c) => false,
+        Some(_) => {
+            let t = line.trim_start();
+            t.starts_with("*** ") && t.trim_end() != END_OF_FILE
+        }
+    }
+}
+
+fn is_hunk_header(line: &str) -> bool {
+    line.chars().next().is_some_and(|c| !is_diff_prefix(c)) && line.trim_start().starts_with("@@")
+}
+
+fn op_path(rest: &str, label: &str) -> Result<String, String> {
+    let path = rest.trim();
+    if path.is_empty() {
+        return Err(format!("{label} requires a path"));
+    }
+    ensure_safe_path(path, label)?;
+    Ok(path.to_owned())
+}
+
+/// `lines[start..]` is the body after `*** Begin Patch`; `offset` numbers lines in errors.
+fn parse_codex(body: &[&str], offset: usize) -> Result<Vec<FileOp>, String> {
+    let mut ops = Vec::new();
+    let mut i = 0;
+    let n = |i: usize| i + offset + 1;
+    while i < body.len() {
+        let line = body[i];
+        let header = line.trim_start();
+        if let Some(rest) = header.strip_prefix(ADD) {
+            let path = op_path(rest, "Add File")?;
+            i += 1;
+            // (text, written with `+`): blank separator lines before the next header are dropped.
+            let mut content: Vec<(&str, bool)> = Vec::new();
+            while let Some(&l) = body.get(i).filter(|l| !is_patch_header(l)) {
+                match l.strip_prefix('+') {
+                    Some(text) => content.push((text, true)),
+                    None if l.trim().is_empty() => content.push(("", false)),
+                    None => return Err(format!("Add File lines must start with + (line {}: `{l}`)", n(i))),
+                }
+                i += 1;
+            }
+            while content.last().is_some_and(|(_, explicit)| !explicit) {
+                content.pop();
+            }
+            let mut text = content.iter().map(|(t, _)| *t).collect::<Vec<_>>().join("\n");
+            if !content.is_empty() {
+                text.push('\n');
+            }
+            ops.push(FileOp::Add { path, text });
+        } else if let Some(rest) = header.strip_prefix(DELETE) {
+            ops.push(FileOp::Delete { path: op_path(rest, "Delete File")? });
+            i += 1;
+        } else if let Some(rest) = header.strip_prefix(UPDATE) {
+            let path = op_path(rest, "Update File")?;
+            i += 1;
+            let mut move_to = None;
+            if let Some(rest) =
+                body.get(i).filter(|l| is_patch_header(l)).and_then(|l| l.trim_start().strip_prefix(MOVE))
+            {
+                move_to = Some(op_path(rest, "Move to")?);
+                i += 1;
+            }
+            let mut hunks = Vec::new();
+            while i < body.len() && !is_patch_header(body[i]) {
+                if body[i].trim().is_empty() {
+                    i += 1;
+                    continue;
+                }
+                hunks.push(parse_codex_hunk(body, &mut i, hunks.is_empty(), offset)?);
+            }
+            // A move alone needs no hunk (JetBrains requires one).
+            if hunks.is_empty() && move_to.is_none() {
+                return Err("Update File requires at least one hunk".into());
+            }
+            ops.push(FileOp::Update { path, move_to, hunks, or: Vec::new() });
+        } else if line.trim().is_empty() {
+            i += 1;
+        } else {
+            return Err(format!("Unexpected patch line: {line}"));
+        }
+    }
+    Ok(ops)
+}
+
+fn parse_codex_hunk(body: &[&str], i: &mut usize, first: bool, offset: usize) -> Result<Hunk, String> {
+    let mut hunk = Hunk::default();
+    let mut bare = false;
+    let mut headed = false;
+    // Several `@@` lines narrow the place down, as in Codex.
+    while let Some(&line) = body.get(*i).filter(|l| is_hunk_header(l)) {
+        let trimmed = line.trim();
+        match parse_range_header(trimmed) {
+            Some((start, ..)) => hunk.old_start = Some(start),
+            None => {
+                let text = trimmed.trim_start_matches('@').trim();
+                // `@@ fn main() @@` repeats the marker at the end sometimes.
+                let text = text.trim_end_matches('@').trim_end();
+                if !text.is_empty() {
+                    hunk.anchors.push(text.to_owned());
+                }
+            }
+        }
+        bare = trimmed == "@@";
+        headed = true;
+        *i += 1;
+    }
+    let n = |i: usize| i + offset + 1;
+    if !headed {
+        let line = body[*i];
+        if !first || !line.chars().next().is_none_or(is_diff_prefix) {
+            return Err(format!("Expected @@ hunk header (line {}: `{line}`)", n(*i)));
+        }
+    }
+    let is_strict_start =
+        |l: &str| !l.is_empty() && !is_patch_header(l) && !is_hunk_header(l) && !l.starts_with(is_diff_prefix);
+    if bare && body.get(*i).is_some_and(|l| is_strict_start(l)) {
+        return parse_strict_pair(body, i);
+    }
+    // Blank lines at the end of a hunk are usually separators, not context.
+    let mut implicit_blanks = 0usize;
+    while let Some(&line) = body.get(*i).filter(|l| !is_hunk_header(l) && !is_patch_header(l)) {
+        if line.trim_end() == END_OF_FILE {
+            hunk.at_eof = true;
+            *i += 1;
+            break;
+        }
+        let parsed = match line.chars().next() {
+            None => Line::Context(String::new()),
+            Some(' ') => Line::Context(line[1..].to_owned()),
+            Some('-') => Line::Remove(line[1..].to_owned()),
+            Some('+') => Line::Add(line[1..].to_owned()),
+            Some(_) if hunk.lines.is_empty() => {
+                return Err(format!("Hunk lines must start with space, +, or - (line {}: `{line}`)", n(*i)));
+            }
+            Some(_) => break,
+        };
+        implicit_blanks = if line.is_empty() { implicit_blanks + 1 } else { 0 };
+        hunk.lines.push(parsed);
+        *i += 1;
+    }
+    hunk.lines.truncate(hunk.lines.len() - implicit_blanks);
+    if hunk.lines.is_empty() {
+        return Err("Empty hunk in Update File".into());
+    }
+    Ok(hunk)
+}
+
+/// `@@`, the old lines, `@@`, the new lines: whole lines without `-` / `+` prefixes.
+fn parse_strict_pair(body: &[&str], i: &mut usize) -> Result<Hunk, String> {
+    let mut old = Vec::new();
+    let mut closed = false;
+    while let Some(&line) = body.get(*i).filter(|l| !is_patch_header(l)) {
+        *i += 1;
+        if line.trim() == "@@" {
+            closed = true;
+            break;
+        }
+        old.push(line);
+    }
+    if !closed {
+        return Err("Strict @@ pair hunk requires second @@ delimiter".into());
+    }
+    let mut new = Vec::new();
+    while let Some(&line) = body.get(*i).filter(|l| !is_patch_header(l) && !is_hunk_header(l)) {
+        new.push(line);
+        *i += 1;
+    }
+    while new.last().is_some_and(|l| l.trim().is_empty()) {
+        new.pop();
+    }
+    if old.is_empty() && new.is_empty() {
+        return Err("Empty hunk in Update File".into());
+    }
+    let lines = old
+        .into_iter()
+        .map(|l| Line::Remove(l.to_owned()))
+        .chain(new.into_iter().map(|l| Line::Add(l.to_owned())))
+        .collect();
+    Ok(Hunk { lines, ..Hunk::default() })
+}
+
+// --- unified diffs -------------------------------------------------------------
+
+#[derive(Default)]
+struct Section {
+    git_old: Option<String>,
+    git_new: Option<String>,
+    /// `---` / `+++` seen; `None` inside is `/dev/null`.
+    old: Option<Option<String>>,
+    new: Option<Option<String>>,
+    new_file: bool,
+    deleted: bool,
+    rename_from: Option<String>,
+    rename_to: Option<String>,
+    /// `old mode` / `new mode`: a permission change, which the tool leaves alone.
+    mode_change: bool,
+    /// `copy from` / `copy to`.
+    copy_from: Option<String>,
+    copy_to: Option<String>,
+    hunks: Vec<Hunk>,
+    line: usize,
+}
+
+fn is_file_start(lines: &[&str], i: usize) -> bool {
+    let l = lines[i];
+    l.starts_with(DIFF_GIT)
+        || (l.starts_with("--- ") && lines.get(i + 1).is_some_and(|n| n.starts_with("+++ ")) && l != "--- ")
+}
+
+/// `offset` numbers lines in errors (the diff may sit inside `*** Begin Patch`).
+fn parse_unified(lines: &[&str], offset: usize) -> Result<Vec<FileOp>, String> {
+    let mut ops = Vec::new();
+    let mut i = 0;
+    let mut section: Option<Section> = None;
+    while i < lines.len() {
+        let line = lines[i];
+        let n = i + offset + 1;
+        if is_file_start(lines, i) && (line.starts_with(DIFF_GIT) || section.as_ref().is_none_or(|s| s.old.is_some())) {
+            if let Some(s) = section.take() {
+                ops.push(finish_section(s)?);
+            }
+            let mut s = Section { line: n, ..Section::default() };
+            if let Some(rest) = line.strip_prefix(DIFF_GIT) {
+                (s.git_old, s.git_new) = split_git_paths(rest);
+                i += 1;
+            }
+            section = Some(s);
+            continue;
+        }
+        let Some(s) = section.as_mut() else {
+            if line.starts_with("@@ ") {
+                return Err(format!("line {n}: a hunk without a `--- a/path` / `+++ b/path` header before it"));
+            }
+            // Text before the first file (a commit message, `Index:` lines).
+            i += 1;
+            continue;
+        };
+        let trimmed = line.trim_start();
+        if let Some(p) = line.strip_prefix("--- ") {
+            s.old = Some(diff_path(p, "a/"));
+        } else if let Some(p) = line.strip_prefix("+++ ") {
+            s.new = Some(diff_path(p, "b/"));
+        } else if trimmed.starts_with("new file mode") {
+            s.new_file = true;
+        } else if trimmed.starts_with("deleted file mode") {
+            s.deleted = true;
+        } else if let Some(p) = trimmed.strip_prefix("rename from ") {
+            s.rename_from = Some(rename_path(p)?);
+        } else if let Some(p) = trimmed.strip_prefix("rename to ") {
+            s.rename_to = Some(rename_path(p)?);
+        } else if trimmed.starts_with("Binary files ") || trimmed == "GIT binary patch" {
+            return Err(format!("Binary git patch is not supported (line {n})"));
+        } else if let Some(p) = trimmed.strip_prefix("copy from ") {
+            s.copy_from = Some(rename_path(p)?);
+        } else if let Some(p) = trimmed.strip_prefix("copy to ") {
+            s.copy_to = Some(rename_path(p)?);
+        } else if trimmed.starts_with("old mode ") || trimmed.starts_with("new mode ") {
+            s.mode_change = true;
+        } else if line.starts_with("@@") {
+            if s.old.is_none() && s.new.is_none() && s.git_old.is_none() {
+                return Err(format!("line {n}: a hunk without a `--- a/path` / `+++ b/path` header before it"));
+            }
+            i += 1;
+            let hunk = parse_unified_hunk(lines, &mut i, line, n)?;
+            s.hunks.push(hunk);
+            continue;
+        } else if !s.hunks.is_empty() && (line.starts_with('+') || line.starts_with('-') || line.starts_with(' ')) {
+            // Lines after a hunk that its counts left out (`-- ` ends `git format-patch` output).
+            if line != "-- " {
+                return Err(format!(
+                    "line {n}: `{line}` follows a hunk but is not part of it; check the hunk's counts"
+                ));
+            }
+            if let Some(s) = section.take() {
+                ops.push(finish_section(s)?);
+            }
+        }
+        // Other extended headers (`index`, modes, similarity) need nothing.
+        i += 1;
+    }
+    if let Some(s) = section {
+        ops.push(finish_section(s)?);
+    }
+    Ok(ops)
+}
+
+/// `@@ -a,b +c,d @@`: hunk lines until the counts are used up; lines beyond
+/// counts that are too small are taken too, and a bare `@@` reads to the next header.
+fn parse_unified_hunk(lines: &[&str], i: &mut usize, header: &str, n: usize) -> Result<Hunk, String> {
+    let counts = parse_range_header(header);
+    if counts.is_none() && header.starts_with("@@ -") {
+        return Err(format!("line {n}: cannot read the hunk header `{header}`"));
+    }
+    let mut hunk = Hunk { old_start: counts.map(|c| c.0), ..Hunk::default() };
+    let (mut old_left, mut new_left) = counts.map_or((usize::MAX, usize::MAX), |c| (c.1, c.2));
+    let mut implicit_blanks = 0usize;
+    let first = *i;
+    while let Some(&line) = lines.get(*i) {
+        let done = old_left == 0 && new_left == 0;
+        if line.starts_with("@@") || is_file_start(lines, *i) {
+            break;
+        }
+        if line.trim_end() == END_OF_FILE {
+            hunk.at_eof = true;
+            *i += 1;
+            break;
+        }
+        if line.starts_with('\\') {
+            match hunk.lines.last() {
+                Some(Line::Remove(_)) => hunk.old_no_newline = true,
+                Some(Line::Add(_)) => hunk.new_no_newline = true,
+                Some(Line::Context(_)) => {
+                    hunk.old_no_newline = true;
+                    hunk.new_no_newline = true;
+                }
+                None => {}
+            }
+            *i += 1;
+            continue;
+        }
+        let parsed = match line.chars().next() {
+            _ if done && (line.is_empty() || line == "-- ") => break,
+            Some(' ') => Line::Context(line[1..].to_owned()),
+            Some('-') => Line::Remove(line[1..].to_owned()),
+            Some('+') => Line::Add(line[1..].to_owned()),
+            // Editors strip the space of empty context lines.
+            None => Line::Context(String::new()),
+            Some(_) if hunk.lines.is_empty() => {
+                return Err(format!(
+                    "Hunk lines must start with space, +, or - (line {}: `{line}`)",
+                    n + 1 + *i - first
+                ));
+            }
+            Some(_) => break,
+        };
+        match parsed {
+            Line::Context(_) => {
+                old_left = old_left.saturating_sub(1);
+                new_left = new_left.saturating_sub(1);
+            }
+            Line::Remove(_) => old_left = old_left.saturating_sub(1),
+            Line::Add(_) => new_left = new_left.saturating_sub(1),
+        }
+        implicit_blanks = if line.is_empty() { implicit_blanks + 1 } else { 0 };
+        hunk.lines.push(parsed);
+        *i += 1;
+    }
+    if counts.is_none() {
+        hunk.lines.truncate(hunk.lines.len() - implicit_blanks);
+    }
+    if hunk.lines.is_empty() {
+        return Err(format!("Empty hunk in Update File (line {n}: `{header}`)"));
+    }
+    Ok(hunk)
+}
+
+/// (old start, old count, new count) of `@@ -a[,b] +c[,d] @@`; extra `@`s (`@@@`) are accepted.
+fn parse_range_header(header: &str) -> Option<(usize, usize, usize)> {
+    let rest = header.trim_start_matches('@').trim_start().strip_prefix('-')?;
+    let (ranges, _) = rest.split_once(" @@").unwrap_or((rest.trim_end_matches('@'), ""));
+    let (old, new) = ranges.split_once(" +")?;
+    let range = |r: &str| -> Option<(usize, usize)> {
+        match r.trim().split_once(',') {
+            Some((s, c)) => Some((s.parse().ok()?, c.parse().ok()?)),
+            None => Some((r.trim().parse().ok()?, 1)),
+        }
+    };
+    let (start, old_count) = range(old)?;
+    let (_, new_count) = range(new)?;
+    Some((start, old_count, new_count))
+}
+
+/// The two paths of `diff --git a/x b/y` (ambiguous with spaces: equal halves win).
+fn split_git_paths(rest: &str) -> (Option<String>, Option<String>) {
+    let rest = rest.trim();
+    if let Some((a, b)) = rest.strip_prefix('"').and_then(|r| r.split_once("\" ")) {
+        return (Some(strip_prefix(&unquote(&format!("\"{a}\"")), "a/")), Some(strip_prefix(&unquote(b), "b/")));
+    }
+    let splits: Vec<usize> = rest.match_indices(" b/").map(|(i, _)| i).collect();
+    let pick = splits.iter().find(|&&i| rest[..i].strip_prefix("a/") == Some(&rest[i + 3..])).or(splits.first());
+    match pick {
+        Some(&i) => (Some(strip_prefix(&rest[..i], "a/")), Some(rest[i + 3..].to_owned())),
+        None => (None, None),
+    }
+}
+
+/// A `---` / `+++` path: `None` for `/dev/null`; timestamps and the `a/` / `b/` prefix removed.
+fn diff_path(raw: &str, prefix: &str) -> Option<String> {
+    let raw = raw.split('\t').next().unwrap_or(raw).trim_end();
+    let path = unquote(raw);
+    if path == "/dev/null" {
+        return None;
+    }
+    Some(strip_prefix(&path, prefix))
+}
+
+fn rename_path(raw: &str) -> Result<String, String> {
+    let path = unquote(raw.trim());
+    if path.is_empty() { Err("Could not determine file path from git diff".into()) } else { Ok(path) }
+}
+
+fn strip_prefix(path: &str, prefix: &str) -> String {
+    path.strip_prefix(prefix).unwrap_or(path).to_owned()
+}
+
+/// Git quotes paths with special characters: `"a/x \"y\""`.
+fn unquote(s: &str) -> String {
+    let Some(inner) = s.strip_prefix('"').and_then(|s| s.strip_suffix('"')) else { return s.to_owned() };
+    let mut out = String::new();
+    let mut chars = inner.chars();
+    while let Some(c) = chars.next() {
+        if c != '\\' {
+            out.push(c);
+            continue;
+        }
+        match chars.next() {
+            Some('n') => out.push('\n'),
+            Some('t') => out.push('\t'),
+            Some(c) => out.push(c),
+            None => {}
+        }
+    }
+    out
+}
+
+fn finish_section(s: Section) -> Result<FileOp, String> {
+    const NO_PATH: &str = "Could not determine file path from git diff";
+    let n = s.line;
+    let old = match &s.old {
+        Some(p) => p.clone(),
+        None => s.rename_from.clone().or_else(|| s.git_old.clone()),
+    };
+    let new = match &s.new {
+        Some(p) => p.clone(),
+        None => s.rename_to.clone().or_else(|| s.git_new.clone()),
+    };
+    if s.copy_from.is_some() || s.copy_to.is_some() {
+        // Git writes a copy only with `-C`; JetBrains reads it as a change of the source.
+        let to = s.copy_to.clone().or(new).ok_or_else(|| format!("{NO_PATH} (line {n})"))?;
+        let from = s.copy_from.clone().or(old).unwrap_or_default();
+        let note = format!(
+            "the copy of {from} to {to} was skipped: copies are not supported; add the new file with `*** Add File` \
+instead"
+        );
+        return Ok(FileOp::Skip { path: to, note });
+    }
+    if s.new_file || (s.old.as_ref().is_some_and(|o| o.is_none())) {
+        let path = new.ok_or_else(|| format!("{NO_PATH} (line {n})"))?;
+        ensure_safe_path(&path, "Add File")?;
+        let mut lines = Vec::new();
+        let mut no_newline = false;
+        for h in &s.hunks {
+            for l in &h.lines {
+                match l {
+                    Line::Add(t) => lines.push(t.as_str()),
+                    _ => return Err(format!("`{path}` is a new file, but its hunk has context or removed lines")),
+                }
+            }
+            no_newline |= h.new_no_newline;
+        }
+        let mut text = lines.join("\n");
+        if !lines.is_empty() && !no_newline {
+            text.push('\n');
+        }
+        return Ok(FileOp::Add { path, text });
+    }
+    if s.deleted || (s.new.as_ref().is_some_and(|n| n.is_none())) {
+        let path = old.ok_or_else(|| format!("{NO_PATH} (line {n})"))?;
+        ensure_safe_path(&path, "Delete File")?;
+        return Ok(FileOp::Delete { path });
+    }
+    // Only git's rename headers say a file moves: plain diffs often name the sides
+    // differently (`--- a.txt.orig` / `+++ a.txt`, `diff -ru old/ new/`).
+    if s.rename_from.is_some() || s.rename_to.is_some() {
+        let path = old.or(new.clone()).ok_or_else(|| format!("{NO_PATH} (line {n})"))?;
+        ensure_safe_path(&path, "Update File")?;
+        let move_to = new.filter(|p| *p != path);
+        if let Some(m) = &move_to {
+            ensure_safe_path(m, "Move to")?;
+        }
+        if s.hunks.is_empty() && move_to.is_none() && !s.mode_change {
+            return Err(format!("line {n}: `{path}` has no changes"));
+        }
+        return Ok(FileOp::Update { path, move_to, hunks: s.hunks, or: Vec::new() });
+    }
+    let path = new.clone().or(old.clone()).ok_or_else(|| format!("{NO_PATH} (line {n})"))?;
+    ensure_safe_path(&path, "Update File")?;
+    if s.hunks.is_empty() {
+        // Only the file mode changes: nothing to do to the text, as in JetBrains.
+        if s.mode_change {
+            return Ok(FileOp::Update { path, move_to: None, hunks: Vec::new(), or: Vec::new() });
+        }
+        return Err(format!("line {n}: `{path}` has no changes"));
+    }
+    let below_first_dir = |p: &Option<String>| p.as_ref().and_then(|p| p.split_once('/')).map(|(_, r)| r.to_owned());
+    let mut or: Vec<String> = Vec::new();
+    let others =
+        if old == new { [None, None, None] } else { [old.clone(), below_first_dir(&new), below_first_dir(&old)] };
+    for p in others.into_iter().flatten() {
+        if !p.is_empty() && p != path && !or.contains(&p) {
+            or.push(p);
+        }
+    }
+    Ok(FileOp::Update { path, move_to: None, hunks: s.hunks, or })
+}
+
+// --- applying -------------------------------------------------------------------
+
+/// How exactly a hunk's lines matched the file, tried in this order.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub enum Fuzz {
+    Exact,
+    TrailingWhitespace,
+    Whitespace,
+    /// Whitespace, and typographic dashes, quotes and spaces as their ASCII forms.
+    Punctuation,
+}
+
+impl Fuzz {
+    fn same(self, a: &str, b: &str) -> bool {
+        match self {
+            Fuzz::Exact => a == b,
+            Fuzz::TrailingWhitespace => a.trim_end() == b.trim_end(),
+            Fuzz::Whitespace => a.trim() == b.trim(),
+            Fuzz::Punctuation => a.trim().chars().map(normalize_char).eq(b.trim().chars().map(normalize_char)),
+        }
+    }
+
+    pub fn describe(self) -> &'static str {
+        match self {
+            Fuzz::Exact => "exactly",
+            Fuzz::TrailingWhitespace => "ignoring trailing whitespace",
+            Fuzz::Whitespace => "ignoring indentation and whitespace",
+            Fuzz::Punctuation => "ignoring whitespace and typographic punctuation (dashes, quotes, spaces)",
+        }
+    }
+}
+
+fn normalize_char(c: char) -> char {
+    match c {
+        '\u{2010}'..='\u{2015}' | '\u{2212}' => '-',
+        '\u{2018}'..='\u{201B}' => '\'',
+        '\u{201C}'..='\u{201F}' => '"',
+        '\u{00A0}' | '\u{2002}'..='\u{200A}' | '\u{202F}' | '\u{205F}' | '\u{3000}' => ' ',
+        c => c,
+    }
+}
+
+const LEVELS: [Fuzz; 4] = [Fuzz::Exact, Fuzz::TrailingWhitespace, Fuzz::Whitespace, Fuzz::Punctuation];
+
+/// The result of [`apply`]: the new text and the hunks that matched only loosely.
+#[derive(Debug, PartialEq, Eq)]
+pub struct Applied {
+    pub text: String,
+    /// (1-based hunk, how it matched) for hunks that did not match exactly.
+    pub fuzzy: Vec<(usize, Fuzz)>,
+}
+
+/// Applies `hunks` in order to `text` (`\n` line endings). A hunk is searched
+/// after the previous one, then (unless it ends the file) from the top. Errors
+/// name the hunk and the lines that were not found.
+pub fn apply(text: &str, hunks: &[Hunk]) -> Result<Applied, String> {
+    let trailing_newline = text.ends_with('\n');
+    let mut lines: Vec<String> = if text.is_empty() {
+        Vec::new()
+    } else {
+        let mut l: Vec<String> = text.split('\n').map(str::to_owned).collect();
+        if trailing_newline {
+            l.pop();
+        }
+        l
+    };
+    let original_len = lines.len();
+    let mut cursor = 0usize;
+    let mut fuzzy = Vec::new();
+    let mut ends_without_newline = None;
+    for (index, hunk) in hunks.iter().enumerate() {
+        let n = index + 1;
+        let file: Vec<&str> = lines.iter().map(String::as_str).collect();
+        let mut anchor_line = None;
+        for anchor in &hunk.anchors {
+            let find =
+                |from: usize| LEVELS.iter().find_map(|level| (from..file.len()).find(|&i| level.same(file[i], anchor)));
+            let found = find(cursor).or_else(|| find(0)).ok_or_else(|| {
+                format!(
+                    "Hunk context not found: {}: cannot find the line `{anchor}` its `@@` header names",
+                    hunk.label(n)
+                )
+            })?;
+            anchor_line = Some(found);
+            cursor = found + 1;
+        }
+        // Line numbers of a diff count the original file: shift them by what earlier hunks added.
+        let shift = |s: usize| (s as isize + lines.len() as isize - original_len as isize).max(0) as usize;
+        let mut old = hunk.old_lines();
+        if old.is_empty() {
+            let at = if !hunk.anchors.is_empty() {
+                cursor
+            } else if hunk.at_eof {
+                file.len()
+            } else {
+                // `@@ -5,0 +6,2 @@` inserts after line 5; without a position, at the end.
+                hunk.old_start.map_or(file.len(), |s| shift(s).min(file.len()))
+            };
+            let new: Vec<String> = hunk.new_lines().into_iter().map(str::to_owned).collect();
+            cursor = at + new.len();
+            lines.splice(at..at, new);
+            continue;
+        }
+        let hint = hunk.old_start.map(|s| shift(s.saturating_sub(1)));
+        // Models often repeat the `@@` line as the hunk's first context line: then the
+        // block starts at the anchor rather than after it.
+        let find = |old: &[&str]| {
+            find_block(&file, old, cursor, hint, hunk.at_eof)
+                .or_else(|| anchor_line.and_then(|a| find_block(&file, old, a, hint, hunk.at_eof)))
+                .or_else(|| (cursor > 0 && !hunk.at_eof).then(|| find_block(&file, old, 0, hint, false)).flatten())
+        };
+        let mut found = find(&old);
+        // A blank last line in the patch that the file does not have (Codex does the same).
+        if found.is_none() && old.last() == Some(&"") {
+            old.pop();
+            if !old.is_empty() {
+                found = find(&old);
+            }
+        }
+        let Some((at, level)) = found else {
+            return Err(mismatch(&file, &old, hint, &hunk.label(n), hunk.at_eof));
+        };
+        if level != Fuzz::Exact {
+            fuzzy.push((n, level));
+        }
+        if at + old.len() == file.len() {
+            if hunk.new_no_newline {
+                ends_without_newline = Some(true);
+            } else if hunk.old_no_newline {
+                ends_without_newline = Some(false);
+            }
+        }
+        // Context lines keep the file's spelling (a loose match must not re-indent them).
+        let mut new = Vec::new();
+        let mut matched = 0usize;
+        for line in &hunk.lines {
+            match line {
+                Line::Context(_) | Line::Remove(_) if matched >= old.len() => {}
+                Line::Context(_) => {
+                    new.push(file[at + matched].to_owned());
+                    matched += 1;
+                }
+                Line::Remove(_) => matched += 1,
+                Line::Add(s) => new.push(s.clone()),
+            }
+        }
+        let removed = old.len();
+        cursor = at + new.len();
+        lines.splice(at..at + removed, new);
+    }
+    let mut result = lines.join("\n");
+    let newline = match ends_without_newline {
+        Some(no) => !no,
+        None => trailing_newline || text.is_empty(),
+    };
+    if newline && !lines.is_empty() {
+        result.push('\n');
+    }
+    Ok(Applied { text: result, fuzzy })
+}
+
+/// Where `old` occurs at or after `from`, as exactly as possible; with a hint,
+/// the occurrence nearest to it. A hunk that ends the file must match its end.
+fn find_block(lines: &[&str], old: &[&str], from: usize, hint: Option<usize>, at_eof: bool) -> Option<(usize, Fuzz)> {
+    if old.len() > lines.len() {
+        return None;
+    }
+    let last = lines.len() - old.len();
+    let matches = |at: usize, level: Fuzz| old.iter().zip(&lines[at..]).all(|(o, l)| level.same(l, o));
+    for level in LEVELS {
+        if at_eof {
+            if last >= from && matches(last, level) {
+                return Some((last, level));
+            }
+            continue;
+        }
+        let mut best: Option<usize> = None;
+        for at in from..=last {
+            if !matches(at, level) {
+                continue;
+            }
+            match hint {
+                None => return Some((at, level)),
+                Some(h) => {
+                    if best.is_none_or(|b| at.abs_diff(h) < b.abs_diff(h)) {
+                        best = Some(at);
+                    }
+                }
+            }
+        }
+        if let Some(at) = best {
+            return Some((at, level));
+        }
+    }
+    None
+}
+
+/// The error for lines that were not found, with the closest partial match.
+fn mismatch(lines: &[&str], old: &[&str], hint: Option<usize>, label: &str, at_eof: bool) -> String {
+    let mut msg = format!("Hunk context not found: {label} does not apply: these lines were not found:\n");
+    for l in old {
+        let _ = writeln!(msg, "  {l}");
+    }
+    // The start with the longest run of matching lines (ignoring whitespace).
+    let mut best: Option<(usize, usize)> = None;
+    for at in 0..lines.len() {
+        let run = old.iter().zip(&lines[at..]).take_while(|(o, l)| Fuzz::Punctuation.same(o, l)).count();
+        let better = match best {
+            None => run > 0,
+            Some((b, r)) => run > r || (run == r && hint.is_some_and(|h| at.abs_diff(h) < b.abs_diff(h))),
+        };
+        if better {
+            best = Some((at, run));
+        }
+    }
+    match best {
+        Some((at, run)) if run < old.len() => {
+            let actual = lines.get(at + run).map_or("(end of file)".to_owned(), |l| format!("`{l}`"));
+            let _ = write!(
+                msg,
+                "Closest match at line {}: line {} is {actual}, but the patch expects `{}`.",
+                at + 1,
+                at + run + 1,
+                old[run]
+            );
+        }
+        Some((at, _)) if at_eof => {
+            let _ = write!(
+                msg,
+                "They occur at line {}, but the hunk is marked `*** End of File` and they do not end the file.",
+                at + 1
+            );
+        }
+        Some((at, _)) => {
+            let _ = write!(msg, "They occur at line {}.", at + 1);
+        }
+        None => {
+            // A common mistake: only part of a line after `-` / ` `.
+            let partial = old
+                .iter()
+                .filter(|o| !o.trim().is_empty())
+                .find_map(|o| lines.iter().position(|l| l.contains(o.trim())).map(|i| (o.trim(), i)));
+            match partial {
+                Some((o, i)) => {
+                    let _ = write!(
+                        msg,
+                        "Line {} contains `{o}` but is `{}`: patch lines must be whole lines, with their indentation.",
+                        i + 1,
+                        lines[i]
+                    );
+                }
+                None => msg.push_str("No line of them is in the file; read the file again before patching it."),
+            }
+        }
+    }
+    msg
+}
+
+#[cfg(test)]
+mod tests;

crates/ide-host/src/mcp/edit/patch/tests.rs

@@ -0,0 +1,584 @@
+//! Parser and engine tests, including JetBrains' `PatchApplyEngineTest` cases.
+
+use super::*;
+
+fn update(ops: &[FileOp]) -> &[Hunk] {
+    match &ops[0] {
+        FileOp::Update { hunks, .. } => hunks,
+        other => panic!("not an update: {other:?}"),
+    }
+}
+
+fn apply_patch(text: &str, patch: &str) -> Result<String, String> {
+    let ops = parse(patch)?;
+    apply(text, update(&ops)).map(|a| a.text)
+}
+
+fn patch(lines: &[&str]) -> String {
+    lines.iter().map(|l| format!("{l}\n")).collect()
+}
+
+fn hunk(lines: &[(char, &str)], at_eof: bool) -> Hunk {
+    let lines = lines
+        .iter()
+        .map(|&(p, t)| match p {
+            '-' => Line::Remove(t.into()),
+            '+' => Line::Add(t.into()),
+            _ => Line::Context(t.into()),
+        })
+        .collect();
+    Hunk { lines, at_eof, ..Hunk::default() }
+}
+
+// --- Codex format -------------------------------------------------------
+
+#[test]
+fn parses_every_codex_operation() {
+    let ops = parse(
+        "*** Begin Patch\n*** Add File: new.txt\n+one\n+two\n*** Delete File: old.txt\n*** Update File: a.rs\n\
+*** Move to: b.rs\n@@ fn main\n ctx\n-old\n+new\n*** End Patch\n",
+    )
+    .unwrap();
+    assert_eq!(
+        ops,
+        vec![
+            FileOp::Add { path: "new.txt".into(), text: "one\ntwo\n".into() },
+            FileOp::Delete { path: "old.txt".into() },
+            FileOp::Update {
+                path: "a.rs".into(),
+                move_to: Some("b.rs".into()),
+                hunks: vec![Hunk {
+                    anchors: vec!["fn main".into()],
+                    lines: vec![Line::Context("ctx".into()), Line::Remove("old".into()), Line::Add("new".into())],
+                    ..Hunk::default()
+                }],
+                or: vec![],
+            },
+        ]
+    );
+}
+
+#[test]
+fn codex_tolerates_wrappers_crlf_and_blank_separators() {
+    let ops = parse(
+        "apply_patch <<'EOF'\r\n*** Begin Patch\r\n*** Add File: x\r\n+a\r\n+\r\n\r\n*** Update File: y\r\n-a\r\n+b\r\n\r\n*** End Patch\r\nEOF",
+    )
+    .unwrap();
+    assert_eq!(ops[0], FileOp::Add { path: "x".into(), text: "a\n\n".into() });
+    assert_eq!(update(&ops[1..])[0].lines, vec![Line::Remove("a".into()), Line::Add("b".into())]);
+    // JetBrains: a heredoc around the patch.
+    let ops = parse(&patch(&["<<EOF", "*** Begin Patch", "*** Add File: notes.txt", "+alpha", "*** End Patch", "EOF"]))
+        .unwrap();
+    assert_eq!(ops, vec![FileOp::Add { path: "notes.txt".into(), text: "alpha\n".into() }]);
+}
+
+#[test]
+fn codex_empty_add_and_move_only() {
+    let ops = parse("*** Begin Patch\n*** Add File: e\n*** Update File: a\n*** Move to: b\n*** End Patch").unwrap();
+    assert_eq!(ops[0], FileOp::Add { path: "e".into(), text: String::new() });
+    assert_eq!(ops[1], FileOp::Update { path: "a".into(), move_to: Some("b".into()), hunks: vec![], or: vec![] });
+}
+
+/// JetBrains `PatchApplyEngineTest`: the parse errors.
+#[test]
+fn codex_errors() {
+    let fails = |lines: &[&str], expected: &str| {
+        let e = parse(&patch(lines)).unwrap_err();
+        assert!(e.contains(expected), "expected `{expected}` in: {e}");
+    };
+    fails(&["oops"], "patch must include *** Begin Patch");
+    fails(&["*** Begin Patch", "*** Add File: notes.txt", "+alpha"], "patch must include *** End Patch");
+    fails(&["*** Begin Patch", "*** End Patch"], "patch did not contain any operations");
+    fails(&["*** Begin Patch", "oops", "*** End Patch"], "Unexpected patch line: oops");
+    fails(&["*** Begin Patch", "*** Add File:   ", "*** End Patch"], "Add File requires a path");
+    fails(
+        &["*** Begin Patch", "*** Add File: notes.txt", "alpha", "*** End Patch"],
+        "Add File lines must start with +",
+    );
+    fails(
+        &["*** Begin Patch", "*** Add File: notes.txt", "+alpha", "beta", "*** End Patch"],
+        "Add File lines must start with + (line 4: `beta`)",
+    );
+    fails(&["*** Begin Patch", "*** Delete File:   ", "*** End Patch"], "Delete File requires a path");
+    fails(&["*** Begin Patch", "*** Update File:   ", "*** End Patch"], "Update File requires a path");
+    fails(
+        &["*** Begin Patch", "*** Update File: s.txt", "*** Move to:   ", "*** End Patch"],
+        "Move to requires a path",
+    );
+    fails(&["*** Begin Patch", "*** Update File: s.txt", "*** End Patch"], "Update File requires at least one hunk");
+    fails(&["*** Begin Patch", "*** Update File: s.txt", "oops", "*** End Patch"], "Expected @@ hunk header");
+    fails(
+        &["*** Begin Patch", "*** Update File: s.txt", " alpha", "-beta", "+gamma", "oops", "*** End Patch"],
+        "Expected @@ hunk header",
+    );
+    fails(
+        &["*** Begin Patch", "*** Update File: s.txt", "@@ def sample()", "oops", "*** End Patch"],
+        "Hunk lines must start with space, +, or -",
+    );
+    fails(&["*** Begin Patch", "*** Update File: s.txt", "@@", "*** End Patch"], "Empty hunk in Update File");
+    fails(
+        &["*** Begin Patch", "*** Update File: s.txt", "@@", "## Goals", "*** End Patch"],
+        "Strict @@ pair hunk requires second @@ delimiter",
+    );
+    fails(
+        &["*** Begin Patch", "*** Delete File: bad\\npath.txt", "*** End Patch"],
+        "Delete File path contains control",
+    );
+    fails(
+        &["*** Begin Patch", "*** Add File: bad\\npath.txt", "+alpha", "*** End Patch"],
+        "Add File path contains control characters or escape sequences",
+    );
+    fails(&["*** Begin Patch", "*** Update File: bad\\npath.txt", "*** End Patch"], "Update File path contains");
+    fails(
+        &["*** Begin Patch", "*** Update File: s.txt", "*** Move to: bad\\npath.txt", "*** End Patch"],
+        "Move to path contains",
+    );
+    fails(&["*** Begin Patch", "*** Update File: a", "-x", "*** End of File", "-y", "*** End Patch"], "Expected @@");
+}
+
+#[test]
+fn codex_hunks_split_on_markers_and_stack_anchors() {
+    let ops = parse(
+        "*** Begin Patch\n*** Update File: a\n@@ class A\n@@ def f():\n-x\n+y\n@@\n-p\n+q\n*** End of File\n*** End Patch",
+    )
+    .unwrap();
+    let hunks = update(&ops);
+    assert_eq!(hunks.len(), 2);
+    assert_eq!(hunks[0].anchors, vec!["class A".to_owned(), "def f():".to_owned()]);
+    assert!(!hunks[0].at_eof && hunks[1].at_eof);
+    assert!(hunks[1].anchors.is_empty());
+}
+
+#[test]
+fn codex_headers_with_line_numbers_are_hints_not_anchors() {
+    for header in ["@@@ -48,6 +48,7 @@@", "@@ -48,6 +48,7 @@", "@@ -48,6 +48,7 @@ fn sample()"] {
+        let ops = parse(&patch(&["*** Begin Patch", "*** Update File: s", header, " a", "-b", "+c", "*** End Patch"]))
+            .unwrap();
+        let h = &update(&ops)[0];
+        assert!(h.anchors.is_empty(), "{header}: {:?}", h.anchors);
+        assert_eq!(h.old_start, Some(48), "{header}");
+    }
+    let ops =
+        parse(&patch(&["*** Begin Patch", "*** Update File: s", "@@ def sample()", " a", "*** End Patch"])).unwrap();
+    assert_eq!(update(&ops)[0].anchors, vec!["def sample()".to_owned()]);
+    // JetBrains `applyHunks works with unified-diff style hunk headers`.
+    let p = patch(&[
+        "*** Begin Patch",
+        "*** Update File: s",
+        "@@ -1,3 +1,4 @@",
+        " alpha",
+        "-beta",
+        "+BETA",
+        " gamma",
+        "+delta",
+        "*** End Patch",
+    ]);
+    assert_eq!(apply_patch("alpha\nbeta\ngamma\n", &p).unwrap(), "alpha\nBETA\ngamma\ndelta\n");
+}
+
+#[test]
+fn strict_pair_hunks() {
+    let p = patch(&[
+        "*** Begin Patch",
+        "*** Update File: s",
+        "@@",
+        "## Goals",
+        "- Keep old wording",
+        "@@",
+        "## Goals",
+        "- Keep new wording",
+        "*** End Patch",
+    ]);
+    let ops = parse(&p).unwrap();
+    let h = &update(&ops)[0];
+    assert!(h.anchors.is_empty());
+    assert_eq!(
+        h.lines,
+        vec![
+            Line::Remove("## Goals".into()),
+            Line::Remove("- Keep old wording".into()),
+            Line::Add("## Goals".into()),
+            Line::Add("- Keep new wording".into()),
+        ]
+    );
+    assert_eq!(apply_patch("# T\n## Goals\n- Keep old wording\n", &p).unwrap(), "# T\n## Goals\n- Keep new wording\n");
+}
+
+#[test]
+fn applies_codex_hunks_with_anchors() {
+    let text = "class A:\n    def f():\n        return 1\nclass B:\n    def f():\n        return 1\n";
+    let patch = "*** Begin Patch\n*** Update File: a.py\n@@ class B:\n     def f():\n-        return 1\n+        return 2\n*** End Patch";
+    assert_eq!(
+        apply_patch(text, patch).unwrap(),
+        "class A:\n    def f():\n        return 1\nclass B:\n    def f():\n        return 2\n"
+    );
+}
+
+#[test]
+fn applies_several_hunks_in_order() {
+    let text = "a\nb\nc\nd\ne\nf\n";
+    let patch = "*** Begin Patch\n*** Update File: x\n@@\n a\n-b\n+B\n@@\n e\n-f\n+F\n+G\n*** End Patch";
+    assert_eq!(apply_patch(text, patch).unwrap(), "a\nB\nc\nd\ne\nF\nG\n");
+}
+
+#[test]
+fn same_lines_twice_match_in_order() {
+    let text = "x\ny\nx\ny\n";
+    let patch = "*** Begin Patch\n*** Update File: f\n@@\n-x\n+1\n@@\n-x\n+2\n*** End Patch";
+    assert_eq!(apply_patch(text, patch).unwrap(), "1\ny\n2\ny\n");
+}
+
+#[test]
+fn end_of_file_hunks_must_end_the_file() {
+    let text = "end\nmid\nend\n";
+    let patch = "*** Begin Patch\n*** Update File: f\n@@\n-end\n+END\n*** End of File\n*** End Patch";
+    assert_eq!(apply_patch(text, patch).unwrap(), "end\nmid\nEND\n");
+    let beta = hunk(&[('-', "beta"), ('+', "BETA")], true);
+    assert_eq!(apply("alpha\nbeta\n", std::slice::from_ref(&beta)).unwrap().text, "alpha\nBETA\n");
+    let e = apply("alpha\nbeta\ngamma\n", &[beta]).unwrap_err();
+    assert!(e.starts_with("Hunk context not found") && e.contains("do not end the file"), "{e}");
+}
+
+#[test]
+fn hunks_out_of_order_are_found_from_the_top() {
+    let hunks = [hunk(&[('-', "one"), ('+', "ONE")], true), hunk(&[('-', "two"), ('+', "TWO")], false)];
+    assert_eq!(apply("one\ntwo\nthree\none\n", &hunks).unwrap().text, "one\nTWO\nthree\nONE\n");
+    let text = "fn a() {\n    one();\n    two();\n}\n";
+    let p =
+        "*** Begin Patch\n*** Update File: f\n@@\n-    two();\n+    2();\n@@\n-    one();\n+    1();\n*** End Patch";
+    assert_eq!(apply_patch(text, p).unwrap(), "fn a() {\n    1();\n    2();\n}\n");
+}
+
+#[test]
+fn many_repeated_hunks_apply_deterministically() {
+    let hunks: Vec<Hunk> = (0..80).map(|i| hunk(&[('-', "alpha"), ('+', &format!("alpha-{i}"))], false)).collect();
+    let text = "alpha\n".repeat(600);
+    let expected: String = (0..80).map(|i| format!("alpha-{i}\n")).collect::<String>() + &"alpha\n".repeat(520);
+    assert_eq!(apply(&text, &hunks).unwrap().text, expected);
+}
+
+#[test]
+fn accepts_the_anchor_repeated_as_context() {
+    let text = "package greet\n\nfunc prefix() string {\n\treturn \"Merhaba, \"\n}\n";
+    let patch = "*** Begin Patch\n*** Update File: f\n@@ func prefix() string {\n func prefix() string {\n-\treturn \"Merhaba, \"\n+\treturn \"Selam, \"\n }\n*** End Patch";
+    assert_eq!(apply_patch(text, patch).unwrap(), "package greet\n\nfunc prefix() string {\n\treturn \"Selam, \"\n}\n");
+}
+
+#[test]
+fn pure_additions_go_after_the_anchor_or_at_the_end() {
+    let text = "fn a() {}\nfn b() {}\n";
+    let after = "*** Begin Patch\n*** Update File: f\n@@ fn a() {}\n+fn a2() {}\n*** End Patch";
+    assert_eq!(apply_patch(text, after).unwrap(), "fn a() {}\nfn a2() {}\nfn b() {}\n");
+    let end = "*** Begin Patch\n*** Update File: f\n@@\n+fn c() {}\n*** End Patch";
+    assert_eq!(apply_patch(text, end).unwrap(), "fn a() {}\nfn b() {}\nfn c() {}\n");
+}
+
+#[test]
+fn fuzz_levels_are_tried_in_order_and_reported() {
+    let text = "fn main() {   \n    let x = 1;\n}\n";
+    let ops =
+        parse("*** Begin Patch\n*** Update File: f\n@@\n fn main() {\n-    let x = 1;\n+    let x = 2;\n*** End Patch")
+            .unwrap();
+    let a = apply(text, update(&ops)).unwrap();
+    assert_eq!(a.text, "fn main() {   \n    let x = 2;\n}\n");
+    assert_eq!(a.fuzzy, vec![(1, Fuzz::TrailingWhitespace)]);
+    let ops = parse("*** Begin Patch\n*** Update File: f\n@@\n-let x = 1;\n+    let y = 1;\n*** End Patch").unwrap();
+    let a = apply(text, update(&ops)).unwrap();
+    assert_eq!(a.text, "fn main() {   \n    let y = 1;\n}\n");
+    assert_eq!(a.fuzzy, vec![(1, Fuzz::Whitespace)]);
+
+    // JetBrains: typographic punctuation, exact matches first.
+    let typographic = "import asyncio  # local import \u{2013} avoids top\u{2011}level dep";
+    let ascii = "import asyncio  # local import - avoids top-level dep";
+    let a =
+        apply(&format!("{typographic}\n"), &[hunk(&[('-', ascii), ('+', "import asyncio  # HELLO")], false)]).unwrap();
+    assert_eq!(a.text, "import asyncio  # HELLO\n");
+    assert_eq!(a.fuzzy, vec![(1, Fuzz::Punctuation)]);
+    let both = [hunk(&[('-', ascii), ('+', "# FIRST")], false), hunk(&[('-', ascii), ('+', "# SECOND")], false)];
+    let text = format!("first\n{typographic}\n{typographic}\n");
+    assert_eq!(apply(&text, &both).unwrap().text, "first\n# FIRST\n# SECOND\n");
+    let text = format!("first\n{typographic}\n{ascii}\n");
+    let exact = apply(&text, &[hunk(&[('-', ascii), ('+', "# EXACT")], false)]).unwrap();
+    assert_eq!(exact.text, format!("first\n{typographic}\n# EXACT\n"));
+}
+
+#[test]
+fn a_trailing_blank_context_line_is_optional() {
+    let text = "a\nb";
+    let patch = "*** Begin Patch\n*** Update File: f\n@@\n-b\n+c\n \n*** End Patch";
+    assert_eq!(apply_patch(text, patch).unwrap(), "a\nc");
+}
+
+#[test]
+fn keeps_a_missing_final_newline_and_handles_empty_files() {
+    assert_eq!(apply_patch("a\nb", "*** Begin Patch\n*** Update File: f\n-b\n+c\n*** End Patch").unwrap(), "a\nc");
+    assert_eq!(apply_patch("", "*** Begin Patch\n*** Update File: f\n+x\n*** End Patch").unwrap(), "x\n");
+    assert_eq!(apply_patch("a\n", "*** Begin Patch\n*** Update File: f\n-a\n*** End Patch").unwrap(), "");
+    let h = hunk(&[('-', "alpha"), ('+', "alpha2"), (' ', "beta")], false);
+    assert_eq!(apply("alpha   \nbeta\n", &[h]).unwrap().text, "alpha2\nbeta\n");
+}
+
+#[test]
+fn reports_where_a_hunk_went_wrong() {
+    let text = "fn a() {\n    one();\n    two();\n}\n";
+    let patch =
+        "*** Begin Patch\n*** Update File: f\n@@\n fn a() {\n     one();\n-    three();\n+    four();\n*** End Patch";
+    let e = apply_patch(text, patch).unwrap_err();
+    assert!(e.starts_with("Hunk context not found: hunk 1 does not apply"), "{e}");
+    assert!(e.contains("  fn a() {\n      one();\n      three();\n"), "{e}");
+    assert!(e.contains("Closest match at line 1: line 3 is `    two();`, but the patch expects `    three();`"), "{e}");
+    let e = apply_patch(text, "*** Begin Patch\n*** Update File: f\n@@ fn zzz\n-x\n*** End Patch").unwrap_err();
+    assert!(e.contains("hunk 1 (@@ fn zzz)") && e.contains("`fn zzz`"), "{e}");
+    let e = apply_patch(text, "*** Begin Patch\n*** Update File: f\n-nothing\n*** End Patch").unwrap_err();
+    assert!(e.contains("No line of them"), "{e}");
+    let e = apply_patch(text, "*** Begin Patch\n*** Update File: f\n-two\n+three\n*** End Patch").unwrap_err();
+    assert!(e.contains("Line 3 contains `two` but is `    two();`: patch lines must be whole lines"), "{e}");
+}
+
+// --- unified diffs ------------------------------------------------------
+
+const GIT: &str = "diff --git a/src/lib.rs b/src/lib.rs
+index 3b18e51..a9e0c2f 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -1,3 +1,3 @@ mod x;
+ fn a() {}
+-fn b() {}
++fn b() { todo!() }
+ fn c() {}
+@@ -10,2 +10,3 @@
+ fn j() {}
++fn k() {}
+ fn l() {}
+diff --git a/new.txt b/new.txt
+new file mode 100644
+index 0000000..e69de29
+--- /dev/null
++++ b/new.txt
+@@ -0,0 +1,2 @@
++hello
++world
+diff --git a/gone.txt b/gone.txt
+deleted file mode 100644
+--- a/gone.txt
++++ /dev/null
+@@ -1 +0,0 @@
+-bye
+diff --git a/old name.txt b/new name.txt
+similarity index 90%
+rename from old name.txt
+rename to new name.txt
+--- a/old name.txt
++++ b/new name.txt
+@@ -1 +1 @@
+-x
++y
+";
+
+#[test]
+fn parses_git_diffs() {
+    let ops = parse(GIT).unwrap();
+    assert_eq!(ops.len(), 4);
+    match &ops[0] {
+        FileOp::Update { path, move_to: None, hunks, or } => {
+            assert_eq!(path, "src/lib.rs");
+            assert!(or.is_empty(), "{or:?}");
+            assert_eq!(hunks.len(), 2);
+            assert_eq!(hunks[0].old_start, Some(1));
+            assert_eq!(hunks[1].lines.len(), 3);
+        }
+        other => panic!("{other:?}"),
+    }
+    assert_eq!(ops[1], FileOp::Add { path: "new.txt".into(), text: "hello\nworld\n".into() });
+    assert_eq!(ops[2], FileOp::Delete { path: "gone.txt".into() });
+    assert!(matches!(&ops[3], FileOp::Update { path, move_to: Some(to), .. }
+        if path == "old name.txt" && to == "new name.txt"));
+}
+
+#[test]
+fn parses_git_diffs_inside_begin_patch() {
+    let ops = parse(&patch(&[
+        "*** Begin Patch",
+        "diff --git a/s.txt b/s.txt",
+        "--- a/s.txt",
+        "+++ b/s.txt",
+        "@@ -1 +1 @@",
+        "-old",
+        "+new",
+        "*** End Patch",
+    ]))
+    .unwrap();
+    assert!(
+        matches!(&ops[..], [FileOp::Update { path, move_to: None, hunks, .. }] if path == "s.txt" && hunks.len() == 1)
+    );
+    // `--- x` removing a `-- x` line keeps a Codex patch a Codex patch.
+    let ops =
+        parse("*** Begin Patch\n*** Update File: q.sql\n@@\n--- old comment\n+-- new comment\n*** End Patch").unwrap();
+    assert_eq!(update(&ops)[0].lines, vec![Line::Remove("-- old comment".into()), Line::Add("-- new comment".into())]);
+}
+
+#[test]
+fn parses_plain_unified_diffs_and_pure_renames() {
+    let ops =
+        parse("--- a.txt\t2024-01-01 10:00:00\n+++ a.txt\t2024-01-02 10:00:00\n@@ -1,2 +1,2 @@\n-a\n+b\n c\n").unwrap();
+    assert!(
+        matches!(&ops[0], FileOp::Update { path, move_to: None, hunks, .. } if path == "a.txt" && hunks.len() == 1)
+    );
+    // Differently named sides are not a move: the `+++` path, else the others.
+    let ops = parse("--- a.txt.orig\n+++ a.txt\n@@ -1 +1 @@\n-a\n+b\n").unwrap();
+    assert!(matches!(&ops[0], FileOp::Update { path, move_to: None, or, .. }
+        if path == "a.txt" && or == &["a.txt.orig"]));
+    let ops = parse(
+        "diff -ru old/src/a.txt new/src/a.txt\n--- old/src/a.txt\t2024-01-01\n+++ new/src/a.txt\t2024-01-02\n@@ -1 +1 @@\n-a\n+b\n",
+    )
+    .unwrap();
+    assert!(matches!(&ops[0], FileOp::Update { path, move_to: None, or, .. }
+        if path == "new/src/a.txt" && or == &["old/src/a.txt", "src/a.txt"]));
+    let ops = parse("diff --git a/x.rs b/y/x.rs\nsimilarity index 100%\nrename from x.rs\nrename to y/x.rs\n").unwrap();
+    assert_eq!(
+        ops[0],
+        FileOp::Update { path: "x.rs".into(), move_to: Some("y/x.rs".into()), hunks: vec![], or: vec![] }
+    );
+    let ops = parse("diff --git a/e b/e\nnew file mode 100644\nindex 0000000..e69de29\n").unwrap();
+    assert_eq!(ops[0], FileOp::Add { path: "e".into(), text: String::new() });
+    let ops = parse("diff --git \"a/sp ace\" \"b/sp ace\"\ndeleted file mode 100644\n").unwrap();
+    assert_eq!(ops[0], FileOp::Delete { path: "sp ace".into() });
+}
+
+#[test]
+fn unified_counts_are_tolerated() {
+    // Counts too large: the next header ends the hunk.
+    let ops = parse("--- a/f\n+++ b/f\n@@ -1,9 +1,9 @@\n-a\n+b\n--- a/g\n+++ b/g\n@@ -1 +1 @@\n-c\n+d\n").unwrap();
+    assert_eq!(ops.len(), 2);
+    assert_eq!(update(&ops)[0].lines.len(), 2);
+    // Counts too small: following hunk lines still belong to it.
+    let ops = parse("--- a/f\n+++ b/f\n@@ -1,1 +1,1 @@\n-a\n+b\n c\n").unwrap();
+    assert_eq!(update(&ops)[0].lines.len(), 3);
+    // A bare `@@` reads to the next header; empty lines are empty context.
+    let ops = parse("--- a/f\n+++ b/f\n@@\n x\n\n-y\n+z\n\n").unwrap();
+    assert_eq!(
+        update(&ops)[0].lines,
+        vec![Line::Context("x".into()), Line::Context(String::new()), Line::Remove("y".into()), Line::Add("z".into())]
+    );
+    // `git format-patch` signature.
+    let ops = parse("Subject: x\n---\n--- a/f\n+++ b/f\n@@ -1 +1 @@\n-a\n+b\n-- \n2.43.0\n").unwrap();
+    assert_eq!(ops.len(), 1);
+    // `*** End of File` inside a unified hunk.
+    let ops = parse("--- a/f\n+++ b/f\n@@\n-a\n+b\n*** End of File\n").unwrap();
+    assert!(update(&ops)[0].at_eof);
+}
+
+#[test]
+fn unified_errors() {
+    assert!(parse("@@ -1 +1 @@\n-a\n+b\n").unwrap_err().contains("patch must include *** Begin Patch"));
+    assert!(parse("--- a/f\n+++ b/f\n@@ -x +y @@\n-a\n").unwrap_err().contains("cannot read"));
+    let e = parse("diff --git a/f b/f\nBinary files a/f and b/f differ\n").unwrap_err();
+    assert!(e.contains("Binary git patch is not supported"), "{e}");
+    assert!(parse("diff --git a/f b/f\nindex 1..2\n").unwrap_err().contains("no changes"));
+    assert!(parse("--- /dev/null\n+++ b/n\n@@ -1 +1 @@\n x\n").unwrap_err().contains("new file"));
+    let e = parse("--- a/f\n+++ b/f\n@@ -1 +1 @@\nzzz\n").unwrap_err();
+    assert!(e.contains("Hunk lines must start with space, +, or - (line 4: `zzz`)"), "{e}");
+}
+
+#[test]
+fn applies_unified_hunks_near_their_line_numbers() {
+    let text = "x\nsame\nx\nx\nx\nsame\nx\n";
+    let ops = parse("--- a/f\n+++ b/f\n@@ -6,1 +6,1 @@\n-same\n+changed\n").unwrap();
+    assert_eq!(apply(text, update(&ops)).unwrap().text, "x\nsame\nx\nx\nx\nchanged\nx\n");
+    // Wrong line numbers still apply where the context is.
+    let ops = parse("--- a/f\n+++ b/f\n@@ -40,2 +40,2 @@\n x\n-same\n+changed\n").unwrap();
+    assert_eq!(apply(text, update(&ops)).unwrap().text, "x\nsame\nx\nx\nx\nchanged\nx\n");
+    // Insertion after line 2 (`-2,0`).
+    let ops = parse("--- a/f\n+++ b/f\n@@ -2,0 +3,1 @@\n+new\n").unwrap();
+    assert_eq!(apply(text, update(&ops)).unwrap().text, "x\nsame\nnew\nx\nx\nx\nsame\nx\n");
+    // Later line numbers shift by what earlier hunks added.
+    let ops = parse("--- a/f\n+++ b/f\n@@ -0,0 +1,2 @@\n+n1\n+n2\n@@ -6,1 +8,1 @@\n-same\n+changed\n").unwrap();
+    assert_eq!(apply(text, update(&ops)).unwrap().text, "n1\nn2\nx\nsame\nx\nx\nx\nchanged\nx\n");
+}
+
+#[test]
+fn applies_the_git_example() {
+    let text = "fn a() {}\nfn b() {}\nfn c() {}\nfn d() {}\nfn e() {}\nfn f() {}\nfn g() {}\nfn h() {}\nfn i() {}\nfn j() {}\nfn l() {}\n";
+    let ops = parse(GIT).unwrap();
+    let out = apply(text, update(&ops)).unwrap().text;
+    assert_eq!(
+        out,
+        "fn a() {}\nfn b() { todo!() }\nfn c() {}\nfn d() {}\nfn e() {}\nfn f() {}\nfn g() {}\nfn h() {}\nfn i() {}\nfn j() {}\nfn k() {}\nfn l() {}\n"
+    );
+}
+
+#[test]
+fn no_newline_markers() {
+    let add = parse("--- /dev/null\n+++ b/n\n@@ -0,0 +1 @@\n+x\n\\ No newline at end of file\n").unwrap();
+    assert_eq!(add[0], FileOp::Add { path: "n".into(), text: "x".into() });
+    // Adding the final newline.
+    let ops = parse("--- a/f\n+++ b/f\n@@ -1,2 +1,2 @@\n a\n-b\n\\ No newline at end of file\n+b\n").unwrap();
+    assert_eq!(apply("a\nb", update(&ops)).unwrap().text, "a\nb\n");
+    // Removing it.
+    let ops = parse("--- a/f\n+++ b/f\n@@ -1,2 +1,2 @@\n a\n-b\n+b\n\\ No newline at end of file\n").unwrap();
+    assert_eq!(apply("a\nb\n", update(&ops)).unwrap().text, "a\nb");
+}
+
+#[test]
+fn splits_git_paths() {
+    assert_eq!(split_git_paths("a/x y b/x y"), (Some("x y".into()), Some("x y".into())));
+    assert_eq!(split_git_paths("a/x b/y"), (Some("x".into()), Some("y".into())));
+    assert_eq!(parse_range_header("@@ -3 +4,0 @@"), Some((3, 1, 0)));
+    assert_eq!(parse_range_header("@@ -1,2 +1,3 @@ fn x"), Some((1, 2, 3)));
+    assert_eq!(parse_range_header("@@@ -48,6 +48,7 @@@"), Some((48, 6, 7)));
+    assert_eq!(parse_range_header("@@ fn x"), None);
+    assert_eq!(unquote("\"a\\\"b\\\\c\""), "a\"b\\c");
+}
+
+#[test]
+fn mode_changes_and_copies_do_not_fail_the_patch() {
+    // A mode-only section is an update without hunks; the hunks of the others still apply.
+    let diff = patch(&[
+        "diff --git a/run.sh b/run.sh",
+        "old mode 100644",
+        "new mode 100755",
+        "diff --git a/a.txt b/a.txt",
+        "--- a/a.txt",
+        "+++ b/a.txt",
+        "@@ -1 +1 @@",
+        "-x",
+        "+y",
+    ]);
+    let ops = parse(&diff).unwrap();
+    assert_eq!(ops.len(), 2);
+    assert_eq!(ops[0], FileOp::Update { path: "run.sh".into(), move_to: None, hunks: Vec::new(), or: Vec::new() });
+    assert_eq!(update(&ops[1..]).len(), 1);
+
+    // A mode change together with a rename is a move.
+    let ops = parse("diff --git a/x b/y\nold mode 100644\nnew mode 100755\nrename from x\nrename to y\n").unwrap();
+    assert!(matches!(&ops[0], FileOp::Update { move_to: Some(m), .. } if m == "y"));
+
+    // A copy is skipped with a note.
+    let diff = patch(&[
+        "diff --git a/src/a.rs b/src/b.rs",
+        "similarity index 90%",
+        "copy from src/a.rs",
+        "copy to src/b.rs",
+        "--- a/src/a.rs",
+        "+++ b/src/b.rs",
+        "@@ -1 +1 @@",
+        "-a",
+        "+b",
+        "diff --git a/c.txt b/c.txt",
+        "--- a/c.txt",
+        "+++ b/c.txt",
+        "@@ -1 +1 @@",
+        "-1",
+        "+2",
+    ]);
+    let ops = parse(&diff).unwrap();
+    assert_eq!(ops.len(), 2);
+    match &ops[0] {
+        FileOp::Skip { path, note } => {
+            assert_eq!(path, "src/b.rs");
+            assert!(note.contains("copy of src/a.rs to src/b.rs") && note.contains("not supported"), "{note}");
+        }
+        other => panic!("{other:?}"),
+    }
+    assert_eq!(ops[1].path(), "c.txt");
+}

crates/ide-host/src/mcp/edit/rename.rs

@@ -0,0 +1,950 @@
+// Ported from JetBrains intellij-community plugins/mcp-server (mcpserver.toolsets/src/general/RefactoringToolset.kt, renameTarget.kt), Apache-2.0.
+//! `rename_refactoring` with the language server's rename. The target is given
+//! as in JetBrains: a `contextSnippet`, else `line` + `column`, else the one
+//! declaration of `symbolName` in the file; `targetIndex` picks from the
+//! candidates an earlier call listed. Failures are results (`ok: false` with an
+//! `error.kind`), not tool errors, so the agent can correct the call.
+//!
+//! Symbols are told apart by their definition (go to definition): the language
+//! server has no PSI elements to compare. It renames code references only;
+//! `searchInComments` / `searchInText` add whole-word occurrences found with
+//! Find in Files.
+
+use super::normalize_newlines;
+use crate::mcp::tool::{Call, Output, Param, ParamType, Tool};
+use crate::ops::search::SearchEvent;
+use ide_core::{DocId, FileEdit, IdeError, IdeResult, Pos, Range, TextEdit, WorkspaceEdit};
+use ide_lsp::types::GotoKind;
+use ide_search::{SearchContext, SearchQuery, SearchScope};
+use parking_lot::Mutex;
+use serde::Serialize;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+/// Occurrences of the name whose definition is looked up when no position is given.
+const MAX_LOOKUPS: usize = 50;
+
+/// Files `searchInText` treats as plain text.
+const TEXT_EXTENSIONS: &[&str] = &["txt", "text", "md", "markdown", "rst", "adoc", "asciidoc", "properties"];
+
+pub(super) fn rename_refactoring() -> Tool {
+    Tool::new(
+        "rename_refactoring",
+        "Rename a symbol and every reference to it. Set preview=true to analyze the rename and write nothing.
+The language server resolves the symbol, so it also updates a reference that a text search cannot
+find. Always prefer this tool over a text replacement.
+
+Point at the symbol with ONE of these, in order of preference: contextSnippet, then line and column.
+With neither of them, the file must declare one symbol with this name. symbolName is always required.
+A position that resolves to another name refuses the rename.
+
+targetIndex is not a third way to point at the symbol. It picks from a candidates list an earlier call
+returned, so repeat that call with every argument it had, and add targetIndex.
+
+Read `applied`. It is the only success signal. Nothing is written in part, except after
+error.kind=write_failed, and its hint says what was written.
+ok=false with candidates asks you to pick one with targetIndex. ok=false with conflicts asks for another
+newName. ok=false with error tells you in `hint` what to correct.
+
+applyAutomaticRenamers has no effect here: the language server renames the symbol and its references. A library or \
+compiled symbol cannot be renamed.
+
+By default, the rename changes no comment, no string literal and no plain-text occurrence of the name.
+Set searchInComments or searchInText to change them too.",
+        |call| async move { run(&call).await },
+    )
+    .write()
+    .param(Param::required("pathInProject", ParamType::String, "Path relative to the project root"))
+    .param(Param::required("symbolName", ParamType::String, "Exact, case-sensitive name of the symbol to rename."))
+    .param(Param::required(
+        "newName",
+        ParamType::String,
+        "New name for the symbol. It must be a valid identifier for the symbol's language.",
+    ))
+    .param(Param::optional(
+        "contextSnippet",
+        ParamType::String,
+        "Optional. Exact fragment of the file that shows the symbol. It must match the file once, and contain \
+symbolName.",
+    ))
+    .param(Param::optional(
+        "line",
+        ParamType::Integer,
+        "Optional. 1-based line of the symbol. Copy it from search_symbol output. Needs column too.",
+    ))
+    .param(Param::optional(
+        "column",
+        ParamType::Integer,
+        "Optional. 1-based column of the symbol. Copy it from search_symbol output. Needs line too.",
+    ))
+    .param(Param::optional(
+        "targetIndex",
+        ParamType::Integer,
+        "Optional. 1-based pick from the candidates list an earlier call returned. Repeat every other argument of \
+that call.",
+    ))
+    .param(Param::optional(
+        "preview",
+        ParamType::Boolean,
+        "Optional. Analyze only: report affects and conflicts, and write nothing. The default is false.",
+    ))
+    .param(Param::optional(
+        "applyAutomaticRenamers",
+        ParamType::Boolean,
+        "Optional. Also rename what the IDE renames along with the symbol. The default is false.",
+    ))
+    .param(Param::optional(
+        "searchInComments",
+        ParamType::Boolean,
+        "Optional. Also rename the name in comments and string literals. The default is false.",
+    ))
+    .param(Param::optional(
+        "searchInText",
+        ParamType::Boolean,
+        "Optional. Also rename the name in plain-text occurrences, such as non-code files. The default is false.",
+    ))
+}
+
+// --- the result ------------------------------------------------------------------
+
+#[derive(Serialize, Default)]
+#[serde(rename_all = "camelCase")]
+struct RenameResult {
+    ok: bool,
+    applied: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    resolved_symbol: Option<SymbolInfo>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    affects: Option<Affects>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    renamed_file: Option<RenamedFile>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    candidates: Option<Vec<Candidate>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    conflicts: Option<Vec<Conflict>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    error: Option<RenameError>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    note: Option<String>,
+}
+
+impl RenameResult {
+    fn failed(kind: &'static str, hint: impl Into<String>) -> Self {
+        Self { error: Some(RenameError { kind, hint: hint.into() }), ..Self::default() }
+    }
+
+    fn with_symbol(mut self, symbol: Option<SymbolInfo>) -> Self {
+        self.resolved_symbol = symbol;
+        self
+    }
+}
+
+#[derive(Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+struct SymbolInfo {
+    name: String,
+    declaration_text: String,
+    declaration_file: String,
+    declaration_line: u32,
+    language: String,
+}
+
+/// The blast radius: files with an edit, and the edits.
+#[derive(Serialize)]
+struct Affects {
+    files: usize,
+    usages: usize,
+}
+
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+struct RenamedFile {
+    previous_path: String,
+    path: String,
+}
+
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+struct Candidate {
+    target_index: usize,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    kind: Option<String>,
+    symbol: SymbolInfo,
+}
+
+#[derive(Serialize)]
+struct Conflict {
+    description: String,
+}
+
+#[derive(Serialize)]
+struct RenameError {
+    kind: &'static str,
+    hint: String,
+}
+
+// --- the call --------------------------------------------------------------------
+
+struct Request {
+    name: String,
+    new_name: String,
+    snippet: Option<String>,
+    position: Option<(i64, i64)>,
+    target_index: Option<i64>,
+    preview: bool,
+    automatic_renamers: bool,
+    in_comments: bool,
+    in_text: bool,
+}
+
+async fn run(call: &Call) -> IdeResult<Output> {
+    let raw = call.str("pathInProject")?;
+    let name = call.str("symbolName")?;
+    let new_name = call.str("newName")?;
+    for (value, arg) in [(&raw, "pathInProject"), (&name, "symbolName"), (&new_name, "newName")] {
+        if value.trim().is_empty() {
+            return Err(IdeError::invalid(format!("{arg} is empty")));
+        }
+    }
+    let (line, column) = (call.opt_i64("line")?, call.opt_i64("column")?);
+    if line.is_some() != column.is_some() {
+        return Err(IdeError::invalid("line and column must be given together"));
+    }
+    let request = Request {
+        name,
+        new_name,
+        snippet: call.opt_str("contextSnippet")?,
+        position: line.zip(column),
+        target_index: call.opt_i64("targetIndex")?,
+        preview: call.flag("preview", false)?,
+        automatic_renamers: call.flag("applyAutomaticRenamers", false)?,
+        in_comments: call.flag("searchInComments", false)?,
+        in_text: call.flag("searchInText", false)?,
+    };
+    let path = call.resolve_inside(&raw)?;
+    if !path.is_file() {
+        return Err(IdeError::not_found(format!("File not found: {raw}")));
+    }
+    let host = call.host();
+    let project = call.project().clone();
+    let (p, target) = (project.clone(), path.clone());
+    let (doc, transient) = host
+        .blocking(move || {
+            // The rename reads and changes files across the project: no buffer may be older than its file.
+            let open: Vec<PathBuf> = p
+                .documents
+                .open_documents()
+                .into_iter()
+                .filter_map(|d| p.documents.snapshot(d).ok().map(|i| i.path.to_path_buf()))
+                .chain(std::iter::once(target.clone()))
+                .collect();
+            super::refresh_from_disk(&p, &open);
+            super::open_document(&p, &target)
+        })
+        .await?;
+    // Closed on every path out, a panic or a dropped call included.
+    let _close = CloseDocument(project.clone(), transient.then_some(doc));
+    Output::json(rename(call, doc, &path, &request).await?)
+}
+
+/// Closes a transient document when dropped.
+struct CloseDocument(Arc<crate::Project>, Option<DocId>);
+
+impl Drop for CloseDocument {
+    fn drop(&mut self) {
+        if let Some(doc) = self.1 {
+            self.0.documents.close(doc);
+        }
+    }
+}
+
+async fn rename(call: &Call, doc: DocId, path: &Path, req: &Request) -> IdeResult<RenameResult> {
+    let snap = call.project().documents.text_snapshot(doc)?;
+    let file = File { call, doc, path, text: &snap.text, language: snap.language.0.clone() };
+    let pos = match resolve_target(&file, req).await? {
+        Resolution::Resolved(pos) => pos,
+        Resolution::Unresolved(kind, hint) => return Ok(RenameResult::failed(kind, hint)),
+        Resolution::Ambiguous(positions) => {
+            let mut candidates = Vec::new();
+            for (i, pos) in positions.iter().enumerate() {
+                let (symbol, kind) = file.symbol_at(&req.name, *pos).await;
+                candidates.push(Candidate { target_index: i + 1, kind, symbol });
+            }
+            let hint = format!(
+                "'{}' matches {} symbols here. Nothing changed. Call again with every argument of this call plus \
+targetIndex, or narrow the call with a contextSnippet that shows the one you mean.",
+                req.name,
+                positions.len()
+            );
+            return Ok(RenameResult { candidates: Some(candidates), ..RenameResult::failed("ambiguous_symbol", hint) });
+        }
+    };
+    let symbol = Some(file.symbol_at(&req.name, pos).await.0);
+    if req.name == req.new_name {
+        let hint = format!("The symbol already has the name '{}'.", req.new_name);
+        return Ok(RenameResult::failed("new_name_matches_current", hint).with_symbol(symbol));
+    }
+    if !plausible_identifier(&req.new_name) {
+        let hint = format!("'{}' is not a valid identifier for {}.", req.new_name, file.language);
+        return Ok(RenameResult::failed("new_name_invalid", hint).with_symbol(symbol));
+    }
+    let host = call.host();
+    let window = call.window();
+    match crate::ops::lsp::lsp_prepare_rename(&host, window, doc, pos).await {
+        Ok(Some(_)) => {}
+        Ok(None) => {
+            let hint = "This symbol cannot be renamed. A library or compiled symbol has to change upstream.";
+            return Ok(RenameResult::failed("not_renamable", hint).with_symbol(symbol));
+        }
+        Err(e) if e.kind == ide_core::error::ErrorKind::Cancelled => return Err(e),
+        Err(e) => return Ok(RenameResult::failed("language_not_supported", no_server_hint(&e)).with_symbol(symbol)),
+    }
+    let request = crate::mcp::tool::request_id();
+    let renamed = tokio::select! {
+        r = crate::ops::lsp::lsp_rename(&host, window, request, doc, pos, req.new_name.clone()) => r,
+        _ = call.cancel.cancelled() => {
+            host.cancel_request(request);
+            return Err(IdeError::cancelled());
+        }
+    };
+    let renamed = match renamed {
+        Ok(r) => r,
+        Err(e) if e.kind == ide_core::error::ErrorKind::Cancelled => return Err(e),
+        // Servers explain a clash with an existing name in the error (gopls: "would conflict with").
+        Err(e) if e.message.to_lowercase().contains("conflict") => {
+            let hint = "A conflict refused the rename and nothing changed. Choose another newName.";
+            let conflicts = Some(vec![Conflict { description: e.message }]);
+            return Ok(RenameResult { conflicts, ..RenameResult::failed("conflicts_found", hint) }.with_symbol(symbol));
+        }
+        Err(e) => return Ok(RenameResult::failed("new_name_refused", e.message).with_symbol(symbol)),
+    };
+    let mut edit = renamed.edit;
+    if edit.files.is_empty() {
+        return Ok(RenameResult::failed("unknown", "The language server found nothing to rename.").with_symbol(symbol));
+    }
+    if req.in_comments || req.in_text {
+        add_text_occurrences(call, &mut edit, req).await?;
+    }
+    for f in &edit.files {
+        let paths: Vec<&Path> = match f {
+            FileEdit::Edit { path, .. } | FileEdit::Create { path, .. } | FileEdit::Delete { path, .. } => vec![path],
+            FileEdit::Rename { from, to } => vec![from, to],
+        };
+        for p in paths {
+            if let Err(e) = super::super::tool::ensure_inside(call.root(), p) {
+                let hint = format!(
+                    "{}. Nothing was renamed. A rename that must change a file outside the project cannot run here.",
+                    e.message
+                );
+                return Ok(RenameResult::failed("read_only_usages", hint).with_symbol(symbol));
+            }
+        }
+    }
+    let mut files: Vec<&Path> = Vec::new();
+    let mut usages = 0;
+    for f in &edit.files {
+        if let FileEdit::Edit { path, edits, .. } = f {
+            usages += edits.len();
+            if !files.contains(&&**path) {
+                files.push(path);
+            }
+        }
+    }
+    let affects = Some(Affects { files: files.len(), usages });
+    let mut notes = Vec::new();
+    if renamed.incomplete.is_some() {
+        notes.push("The language server reported that the references may be incomplete.");
+    }
+    if req.automatic_renamers {
+        notes.push(
+            "applyAutomaticRenamers had no effect: the language server renames the symbol and its references only.",
+        );
+    }
+    let note = (!notes.is_empty()).then(|| notes.join(" "));
+    if req.preview {
+        return Ok(RenameResult { ok: true, affects, resolved_symbol: symbol, note, ..RenameResult::default() });
+    }
+    // The IDE's configuration among the files: the user agrees first.
+    let mut checked: Vec<&Path> = Vec::new();
+    for f in &edit.files {
+        let paths: Vec<&Path> = match f {
+            FileEdit::Edit { path, .. } | FileEdit::Create { path, .. } | FileEdit::Delete { path, .. } => vec![path],
+            FileEdit::Rename { from, to } => vec![from, to],
+        };
+        for p in paths {
+            if !checked.contains(&p) {
+                checked.push(p);
+                call.check_writable(p).await?;
+            }
+        }
+    }
+    let renamed_file = edit.files.iter().find_map(|f| match f {
+        FileEdit::Rename { from, to } if super::same_file(from, path) => {
+            Some(RenamedFile { previous_path: call.display(from), path: call.display(to) })
+        }
+        _ => None,
+    });
+    let (h, w) = (host.clone(), window.to_owned());
+    let written = crate::ops::lsp::apply_workspace_edit(&h, &w, edit).await;
+    if let Err(e) = written {
+        let hint = format!("The rename stopped while it wrote. {} Read the files again before you retry.", e.message);
+        return Ok(RenameResult::failed("write_failed", hint).with_symbol(symbol));
+    }
+    Ok(RenameResult {
+        ok: true,
+        applied: true,
+        resolved_symbol: symbol,
+        affects,
+        renamed_file,
+        note,
+        ..RenameResult::default()
+    })
+}
+
+fn no_server_hint(e: &IdeError) -> String {
+    format!(
+        "No language server can rename in this file ({}), so nothing was renamed. Without one, change the \
+occurrences with apply_patch.",
+        e.message
+    )
+}
+
+/// Refuses only what no language accepts in a name: whitespace, separators, a leading digit.
+fn plausible_identifier(name: &str) -> bool {
+    !name.starts_with(|c: char| c.is_ascii_digit())
+        && !name.chars().any(|c| c.is_whitespace() || c.is_control() || ".,;:()[]{}<>\"'`/\\+*=!?&|^%#~".contains(c))
+}
+
+// --- the target ------------------------------------------------------------------
+
+enum Resolution {
+    Resolved(Pos),
+    /// Several symbols, in document order; `targetIndex` is 1-based.
+    Ambiguous(Vec<Pos>),
+    Unresolved(&'static str, String),
+}
+
+/// The file the rename starts in.
+struct File<'a> {
+    call: &'a Call,
+    doc: DocId,
+    path: &'a Path,
+    text: &'a str,
+    language: String,
+}
+
+impl File<'_> {
+    fn line(&self, line: u32) -> &str {
+        self.text.split('\n').nth(line as usize).unwrap_or("")
+    }
+
+    /// Where the symbol at `pos` is defined; `None` without an answer.
+    async fn definition(&self, pos: Pos) -> Option<(PathBuf, Pos)> {
+        let host = self.call.host();
+        let found = crate::ops::lsp::lsp_goto(&host, self.call.window(), self.doc, pos, GotoKind::Definition).await;
+        let loc = found.ok()?.into_iter().find(|l| l.uri.is_none())?;
+        Some((PathBuf::from(&*loc.path), loc.range.start))
+    }
+
+    /// Whether the language server can rename at `pos`; `Err` without one.
+    async fn renameable(&self, pos: Pos) -> Result<bool, Resolution> {
+        let host = self.call.host();
+        match crate::ops::lsp::lsp_prepare_rename(&host, self.call.window(), self.doc, pos).await {
+            Ok(found) => Ok(found.is_some()),
+            Err(e) => Err(Resolution::Unresolved("language_not_supported", no_server_hint(&e))),
+        }
+    }
+
+    /// The symbol (from its definition when known) and its outline kind.
+    async fn symbol_at(&self, name: &str, pos: Pos) -> (SymbolInfo, Option<String>) {
+        let (file, at) = match self.definition(pos).await {
+            Some((file, at)) if super::same_file(&file, self.path) => (self.path.to_path_buf(), at),
+            Some((file, at)) => (file, at),
+            None => (self.path.to_path_buf(), pos),
+        };
+        let declaration_text = if file == self.path {
+            self.line(at.line).trim().to_owned()
+        } else {
+            let project = self.call.project();
+            project
+                .text_of(&file)
+                .ok()
+                .and_then(|t| t.split('\n').nth(at.line as usize).map(|l| l.trim().to_owned()))
+                .unwrap_or_default()
+        };
+        let kind = if file == self.path { self.kind_at(at).await } else { None };
+        let symbol = SymbolInfo {
+            name: name.to_owned(),
+            declaration_text,
+            declaration_file: self.call.display(&file),
+            declaration_line: at.line + 1,
+            language: self.language.clone(),
+        };
+        (symbol, kind)
+    }
+
+    /// The outline kind (`field`, `method`) of the declaration whose name is at `pos`.
+    async fn kind_at(&self, pos: Pos) -> Option<String> {
+        let host = self.call.host();
+        let outline = crate::ops::doc::doc_outline(&host, self.call.window(), self.doc).await.ok()?;
+        let mut stack: Vec<&ide_core::OutlineItem> = outline.iter().collect();
+        while let Some(item) = stack.pop() {
+            let r = item.selection_range;
+            if r.start <= pos && pos <= r.end {
+                let kind = format!("{:?}", item.kind);
+                return Some(kind[..1].to_lowercase() + &kind[1..]);
+            }
+            stack.extend(item.children.iter());
+        }
+        None
+    }
+
+    /// Positions of `name` as an identifier (outside comments and strings when a grammar knows them).
+    async fn identifiers(&self, name: &str) -> Vec<Pos> {
+        let host = self.call.host();
+        match crate::ops::syntax::syntax_identifiers(&host, self.call.window(), self.doc, name.to_owned(), None).await {
+            Ok(found) if !found.is_empty() => found.into_iter().map(|o| o.range.start).collect(),
+            _ => word_positions(self.text, name),
+        }
+    }
+}
+
+/// The symbol the caller pointed at, or why the tool cannot tell which one it is.
+/// `targetIndex` picks from the list of the branch the other arguments select.
+async fn resolve_target(file: &File<'_>, req: &Request) -> IdeResult<Resolution> {
+    let resolution = if let Some(snippet) = &req.snippet {
+        by_snippet(file, snippet, &req.name).await
+    } else if let Some((line, column)) = req.position {
+        by_position(file, line, column, &req.name).await
+    } else {
+        by_declaration(file, &req.name).await?
+    };
+    let Some(index) = req.target_index else { return Ok(resolution) };
+    Ok(match resolution {
+        Resolution::Ambiguous(candidates) => pick(&candidates, index),
+        // One symbol now: only a pick of the first agrees with it; the code changed since the list.
+        Resolution::Resolved(pos) if index == 1 => Resolution::Resolved(pos),
+        Resolution::Resolved(pos) => pick(&[pos], index),
+        unresolved => unresolved,
+    })
+}
+
+fn pick(candidates: &[Pos], index: i64) -> Resolution {
+    let n = candidates.len();
+    if index < 1 || index as usize > n {
+        return Resolution::Unresolved(
+            "target_index_out_of_range",
+            format!(
+                "targetIndex {index} is outside 1..{n}. This call reports {n} candidate(s). Send the same \
+pathInProject, symbolName and contextSnippet as the call that listed them."
+            ),
+        );
+    }
+    Resolution::Resolved(candidates[index as usize - 1])
+}
+
+async fn by_snippet(file: &File<'_>, snippet: &str, name: &str) -> Resolution {
+    if snippet.trim().is_empty() {
+        return Resolution::Unresolved("snippet_not_found", "contextSnippet is blank.".into());
+    }
+    let needle = normalize_newlines(snippet);
+    if !needle.contains(name) {
+        return Resolution::Unresolved(
+            "name_mismatch",
+            format!("contextSnippet does not contain '{name}'. Pass a snippet that shows the symbol."),
+        );
+    }
+    let start = match find_snippet(file.text, &needle) {
+        SnippetMatch::NotFound => {
+            return Resolution::Unresolved(
+                "snippet_not_found",
+                "contextSnippet is not in this file. Read the file again and copy the snippet from its current text."
+                    .into(),
+            );
+        }
+        SnippetMatch::NotUnique => {
+            return Resolution::Unresolved(
+                "snippet_not_unique",
+                "contextSnippet matches this file more than once. Extend it until it is unique.".into(),
+            );
+        }
+        SnippetMatch::At(start) => start,
+    };
+    let mut symbols: Vec<(Option<(PathBuf, Pos)>, Pos)> = Vec::new();
+    // Why an occurrence could not be asked about; reported only when no other one resolves.
+    let mut refused = None;
+    for pos in snippet_occurrences(file.text, start, needle.len(), name) {
+        match file.renameable(pos).await {
+            Ok(true) => {}
+            Ok(false) => continue,
+            Err(no_server) => {
+                refused.get_or_insert(no_server);
+                continue;
+            }
+        }
+        let definition = file.definition(pos).await;
+        if definition.is_none() || !symbols.iter().any(|(d, _)| *d == definition) {
+            symbols.push((definition, pos));
+        }
+    }
+    if let (true, Some(refused)) = (symbols.is_empty(), refused) {
+        return refused;
+    }
+    match symbols.len() {
+        0 => Resolution::Unresolved(
+            "symbol_not_found",
+            format!("'{name}' inside contextSnippet does not resolve to a symbol that can be renamed."),
+        ),
+        1 => Resolution::Resolved(symbols[0].1),
+        _ => Resolution::Ambiguous(symbols.into_iter().map(|(_, p)| p).collect()),
+    }
+}
+
+async fn by_position(file: &File<'_>, line: i64, column: i64, name: &str) -> Resolution {
+    let line_count = file.text.split('\n').count() as i64;
+    if line < 1 || column < 1 || line > line_count {
+        return Resolution::Unresolved(
+            "position_out_of_bounds",
+            format!("Position {line}:{column} is outside this file. Both numbers are 1-based."),
+        );
+    }
+    let text = file.line(line as u32 - 1);
+    let units: Vec<u16> = text.encode_utf16().collect();
+    // The column has to stay on the named line: past its end it would land further down.
+    if column as usize - 1 > units.len() {
+        return Resolution::Unresolved(
+            "position_out_of_bounds",
+            format!("Column {column} is past the end of line {line}. Both numbers are 1-based."),
+        );
+    }
+    let pos = Pos::new(line as u32 - 1, column as u32 - 1);
+    let word = word_at(&units, pos.col as usize);
+    let in_code = file
+        .identifiers(name)
+        .await
+        .iter()
+        .any(|p| p.line == pos.line && p.col <= pos.col && pos.col <= p.col + units_len(name));
+    match word {
+        Some((start, w)) if w == name && in_code => {
+            let at = Pos::new(pos.line, start as u32);
+            match file.renameable(at).await {
+                Ok(true) => Resolution::Resolved(at),
+                Ok(false) => Resolution::Unresolved(
+                    "symbol_not_found",
+                    format!("No symbol that can be renamed sits at {line}:{column}."),
+                ),
+                Err(no_server) => no_server,
+            }
+        }
+        Some((_, other)) if other != name => Resolution::Unresolved(
+            "name_mismatch",
+            format!("Position {line}:{column} resolves to '{other}', not to '{name}'. Nothing was renamed."),
+        ),
+        _ => Resolution::Unresolved(
+            "symbol_not_found",
+            format!("No symbol that can be renamed sits at {line}:{column}."),
+        ),
+    }
+}
+
+/// The declarations of `name` in this file: the distinct definitions of its occurrences
+/// that lie in this file (declared-looking occurrences without go to definition).
+async fn by_declaration(file: &File<'_>, name: &str) -> IdeResult<Resolution> {
+    let occurrences = file.identifiers(name).await;
+    let mut declarations: Vec<Pos> = Vec::new();
+    let mut answered = false;
+    for pos in occurrences.iter().take(MAX_LOOKUPS) {
+        if file.call.cancel.is_cancelled() {
+            return Err(IdeError::cancelled());
+        }
+        if let Some((path, at)) = file.definition(*pos).await {
+            answered = true;
+            if super::same_file(&path, file.path) && !declarations.contains(&at) {
+                declarations.push(at);
+            }
+        }
+    }
+    if !answered {
+        declarations = occurrences.into_iter().filter(|p| is_declaration(file.text, *p)).collect();
+    }
+    declarations.sort();
+    Ok(match declarations.len() {
+        0 => Resolution::Unresolved(
+            "symbol_not_found",
+            format!("No symbol named '{name}' is declared in this file. Pass the file that declares it."),
+        ),
+        1 => Resolution::Resolved(declarations[0]),
+        _ => Resolution::Ambiguous(declarations),
+    })
+}
+
+fn units_len(s: &str) -> u32 {
+    s.encode_utf16().count() as u32
+}
+
+fn is_word_unit(u: u16) -> bool {
+    char::from_u32(u as u32).is_some_and(|c| c.is_alphanumeric() || c == '_' || c == '$') || u >= 0x80
+}
+
+/// The identifier-like word touching UTF-16 column `col`: (start column, word).
+fn word_at(units: &[u16], col: usize) -> Option<(usize, String)> {
+    let touches = |i: usize| units.get(i).is_some_and(|&u| is_word_unit(u));
+    let at = if touches(col) {
+        col
+    } else if col > 0 && touches(col - 1) {
+        col - 1
+    } else {
+        return None;
+    };
+    let start = (0..=at).rev().take_while(|&i| touches(i)).last().unwrap_or(at);
+    let end = (at..units.len()).take_while(|&i| touches(i)).last().map_or(at, |e| e + 1);
+    Some((start, String::from_utf16_lossy(&units[start..end])))
+}
+
+enum SnippetMatch {
+    NotFound,
+    NotUnique,
+    /// The byte offset of the only occurrence.
+    At(usize),
+}
+
+/// Where `needle` occurs in `text`, overlapping occurrences included.
+fn find_snippet(text: &str, needle: &str) -> SnippetMatch {
+    let Some(start) = text.find(needle) else { return SnippetMatch::NotFound };
+    // One character further, not one byte: the needle may start with a multibyte character.
+    let step = needle.chars().next().map_or(1, char::len_utf8);
+    if text[start + step..].contains(needle) { SnippetMatch::NotUnique } else { SnippetMatch::At(start) }
+}
+
+/// Whole-word occurrences of `name` inside the `len` bytes of `text` from byte `start`
+/// (a snippet's place in the file): the file's text around an occurrence decides whether
+/// it is a whole word, so a snippet cut in the middle of a word does not make one.
+fn snippet_occurrences(text: &str, start: usize, len: usize, name: &str) -> Vec<Pos> {
+    let is_word = |c: char| c.is_alphanumeric() || c == '_' || c == '$';
+    let mut out = Vec::new();
+    for (at, _) in text[start..start + len].match_indices(name) {
+        let at = start + at;
+        let before = text[..at].chars().next_back();
+        let after = text[at + name.len()..].chars().next();
+        if before.is_some_and(is_word) || after.is_some_and(is_word) {
+            continue;
+        }
+        let line_start = text[..at].rfind('\n').map_or(0, |i| i + 1);
+        out.push(Pos::new(text[..at].matches('\n').count() as u32, units_len(&text[line_start..at])));
+    }
+    out
+}
+
+/// Whole-word occurrences of `name` (0-based line, UTF-16 column).
+fn word_positions(text: &str, name: &str) -> Vec<Pos> {
+    let is_word = |c: char| c.is_alphanumeric() || c == '_' || c == '$';
+    let mut out = Vec::new();
+    for (line_no, line) in text.split('\n').enumerate() {
+        for (at, _) in line.match_indices(name) {
+            let before = line[..at].chars().next_back();
+            let after = line[at + name.len()..].chars().next();
+            if before.is_some_and(is_word) || after.is_some_and(is_word) {
+                continue;
+            }
+            out.push(Pos::new(line_no as u32, units_len(&line[..at])));
+        }
+    }
+    out
+}
+
+/// Words that introduce a declaration of the name after them.
+const DECLARATION_KEYWORDS: &[&str] = &[
+    "fn",
+    "def",
+    "class",
+    "struct",
+    "enum",
+    "trait",
+    "interface",
+    "type",
+    "func",
+    "function",
+    "fun",
+    "let",
+    "const",
+    "var",
+    "val",
+    "mod",
+    "module",
+    "object",
+    "record",
+    "typealias",
+    "protocol",
+    "union",
+    "namespace",
+    "package",
+    "static",
+    "macro_rules!",
+];
+
+/// Whether the occurrence at `p` follows a declaration keyword (`fn name`, `let mut name`).
+fn is_declaration(text: &str, p: Pos) -> bool {
+    let Some(line) = text.split('\n').nth(p.line as usize) else { return false };
+    let mut units = 0u32;
+    let byte = line
+        .char_indices()
+        .find(|(_, c)| {
+            let here = units >= p.col;
+            units += c.len_utf16() as u32;
+            here
+        })
+        .map_or(line.len(), |(i, _)| i);
+    let mut words = line[..byte].split_whitespace().rev();
+    match words.next() {
+        Some("mut") => words.next() == Some("let"),
+        Some(w) => DECLARATION_KEYWORDS.contains(&w),
+        None => false,
+    }
+}
+
+// --- comments and text -------------------------------------------------------------
+
+/// Adds whole-word occurrences of the old name to `edit`: in comments and string
+/// literals of the files it changes, and in plain-text files of the project.
+async fn add_text_occurrences(call: &Call, edit: &mut WorkspaceEdit, req: &Request) -> IdeResult<()> {
+    let edited: Vec<PathBuf> = edit
+        .files
+        .iter()
+        .filter_map(|f| match f {
+            FileEdit::Edit { path, .. } => Some(path.to_path_buf()),
+            _ => None,
+        })
+        .collect();
+    let mut found = Vec::new();
+    if req.in_comments {
+        let scope = || SearchScope::Files { paths: edited.iter().cloned().map(Into::into).collect() };
+        found.extend(occurrences(call, &req.name, scope(), SearchContext::InComments).await?);
+        found.extend(occurrences(call, &req.name, scope(), SearchContext::InStringLiterals).await?);
+    }
+    if req.in_text {
+        let text_file = |p: &Path| {
+            p.extension().and_then(|e| e.to_str()).is_some_and(|e| TEXT_EXTENSIONS.contains(&e.to_lowercase().as_str()))
+        };
+        found.extend(
+            occurrences(call, &req.name, SearchScope::Project, SearchContext::Any)
+                .await?
+                .into_iter()
+                .filter(|(p, _)| text_file(p) && !edited.iter().any(|e| super::same_file(e, p))),
+        );
+    }
+    for (path, range) in found {
+        let text_edit = TextEdit { range, new_text: req.new_name.clone() };
+        let entry = edit.files.iter_mut().find_map(|f| match f {
+            FileEdit::Edit { path: p, edits, .. } if super::same_file(p, &path) => Some(edits),
+            _ => None,
+        });
+        match entry {
+            Some(edits) => {
+                let overlaps =
+                    edits.iter().any(|e| e.range.start < range.end && range.start < e.range.end || e.range == range);
+                if !overlaps {
+                    edits.push(text_edit);
+                }
+            }
+            None => edit.files.push(FileEdit::Edit { path: path.into(), edits: vec![text_edit], version: None }),
+        }
+    }
+    Ok(())
+}
+
+/// Whole-word, case-sensitive Find in Files matches of `name`.
+async fn occurrences(
+    call: &Call,
+    name: &str,
+    scope: SearchScope,
+    context: SearchContext,
+) -> IdeResult<Vec<(PathBuf, Range)>> {
+    let query = SearchQuery {
+        pattern: name.to_owned(),
+        is_regex: false,
+        case_sensitive: true,
+        whole_word: true,
+        include: Vec::new(),
+        exclude: Vec::new(),
+        scope,
+        max_matches: 0,
+        context,
+    };
+    let host = call.host();
+    let request = crate::mcp::tool::request_id();
+    let files = Arc::new(Mutex::new(Vec::new()));
+    let emit: crate::ops::Emit<SearchEvent> = {
+        let files = files.clone();
+        Arc::new(move |event| {
+            if let SearchEvent::File { file } = event {
+                files.lock().push(file);
+            }
+        })
+    };
+    let search = crate::ops::search::start(&host, call.window(), request, query, emit);
+    tokio::pin!(search);
+    tokio::select! {
+        r = &mut search => r?,
+        _ = call.cancel.cancelled() => {
+            host.cancel_request(request);
+            let _ = search.await;
+            return Err(IdeError::cancelled());
+        }
+    }
+    let width = units_len(name);
+    let mut out = Vec::new();
+    for file in std::mem::take(&mut *files.lock()) {
+        for m in &file.matches {
+            for &(from, _) in &m.ranges {
+                let start = Pos::new(m.line, m.text_offset + from);
+                out.push((file.path.to_path_buf(), Range::new(start, Pos::new(m.line, start.col + width))));
+            }
+        }
+    }
+    Ok(out)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn finds_whole_words_in_utf16_columns() {
+        let text = "let foo = foo_bar + foo;\n// ä foo\nfoofoo";
+        assert_eq!(word_positions(text, "foo"), vec![Pos::new(0, 4), Pos::new(0, 20), Pos::new(1, 5)]);
+        let units: Vec<u16> = "  int counter;".encode_utf16().collect();
+        assert_eq!(word_at(&units, 6), Some((6, "counter".into())));
+        assert_eq!(word_at(&units, 13), Some((6, "counter".into())));
+        assert_eq!(word_at(&units, 0), None);
+    }
+
+    #[test]
+    fn finds_snippets_starting_with_multibyte_characters() {
+        let text = "let äb = 1;\nlet äb2 = äb;\n";
+        assert!(matches!(find_snippet(text, "äb"), SnippetMatch::NotUnique));
+        assert!(matches!(find_snippet(text, "äb = 1"), SnippetMatch::At(4)));
+        assert!(matches!(find_snippet(text, "ö"), SnippetMatch::NotFound));
+        // Overlapping occurrences are two.
+        assert!(matches!(find_snippet("aaa", "aa"), SnippetMatch::NotUnique));
+    }
+
+    #[test]
+    fn snippet_occurrences_are_whole_words_of_the_file() {
+        let text = "let beta = 1;\nlet x = alphabeta + beta;\n";
+        // The snippet starts inside `alphabeta`: its `beta` is not a word of the file.
+        let needle = "beta + beta";
+        let SnippetMatch::At(start) = find_snippet(text, needle) else { panic!() };
+        assert_eq!(snippet_occurrences(text, start, needle.len(), "beta"), vec![Pos::new(1, 20)]);
+        let text = "ä beta";
+        assert_eq!(snippet_occurrences(text, 0, text.len(), "beta"), vec![Pos::new(0, 2)]);
+    }
+
+    #[test]
+    fn recognizes_declarations_and_identifiers() {
+        let text = "use x;\nprint(count)\nlet mut count = 1;\nfn count() {}\n";
+        assert!(!is_declaration(text, Pos::new(1, 6)));
+        assert!(is_declaration(text, Pos::new(2, 8)) && is_declaration(text, Pos::new(3, 3)));
+        assert!(plausible_identifier("hitCount") && plausible_identifier("kebab-case") && plausible_identifier("$x"));
+        assert!(!plausible_identifier("1abc") && !plausible_identifier("bad name") && !plausible_identifier("a.b"));
+    }
+}

crates/ide-host/src/mcp/editors.rs

@@ -0,0 +1,98 @@
+use super::tool::{Call, Output, Param, ParamType, Tool};
+use ide_core::{Diagnostic, IdeResult, Severity};
+use serde_json::{Value, json};
+
+pub fn tools() -> Vec<Tool> {
+    vec![
+        Tool::new(
+            "get_all_open_file_paths",
+            "Returns active editor's and other open editors' file paths relative to the project root.
+
+Use this tool to explore current open editors.",
+            open_editors,
+        ),
+        Tool::new(
+            "get_current_file",
+            "Returns the focused editor's file and selection reported by the IDE.
+Selection lines and UTF-16 columns are 1-based, end exclusive.
+Selected text is limited to 65536 UTF-16 units.",
+            current_file,
+        ),
+        Tool::new(
+            "get_file_problems",
+            "Returns the problems for a file as reported by the IDE's Problems view, including language servers
+and inspections after profile filtering. This reflects what the Problems view shows, rather than a fresh analysis.
+Lines and UTF-16 columns are 1-based.",
+            file_problems,
+        )
+        .param(Param::required("filePath", ParamType::String, "Path relative to the project root"))
+        .param(Param::optional(
+            "errorsOnly",
+            ParamType::Boolean,
+            "Whether to include only errors or include both errors and warnings",
+        )),
+        Tool::new(
+            "get_project_problems",
+            "Returns the project's problems as reported by the IDE's Problems view, including language servers
+and inspections after profile filtering. This reflects what the Problems view shows, rather than a fresh analysis.
+Lines and UTF-16 columns are 1-based.",
+            project_problems,
+        ),
+    ]
+}
+
+async fn open_editors(call: Call) -> IdeResult<Output> {
+    let windows = call.host.mcp_windows(call.root());
+    let open = call.host.mcp_reports.editors(&windows);
+    let active = call.host.mcp_reports.focused(call.window());
+    Output::json(json!({
+        "activeFilePath": active.map(|e| call.display(&e.path.0)),
+        "openFiles": open.iter().map(|p| call.display(p)).collect::<Vec<_>>(),
+    }))
+}
+
+async fn current_file(call: Call) -> IdeResult<Output> {
+    let editor = call.host.mcp_reports.focused(call.window());
+    Output::json(match editor {
+        None => json!({}),
+        Some(e) => json!({
+            "filePath": call.display(&e.path.0), "selectedText": e.selected_text,
+            "selection": {
+                "startLine": e.selection.start.line + 1, "startColumn": e.selection.start.col + 1,
+                "endLine": e.selection.end.line + 1, "endColumn": e.selection.end.col + 1,
+            },
+        }),
+    })
+}
+
+fn problem(d: Diagnostic, text: &str) -> Value {
+    json!({
+        "severity": d.severity, "description": d.message,
+        "lineContent": text.lines().nth(d.range.start.line as usize).unwrap_or_default(),
+        "line": d.range.start.line + 1, "column": d.range.start.col + 1, "source": d.source, "code": d.code,
+    })
+}
+
+async fn file_problems(call: Call) -> IdeResult<Output> {
+    let path = call.resolve_readable(&call.str("filePath")?).await?;
+    let errors_only = call.flag("errorsOnly", true)?;
+    let files = call.host.mcp_reports.problems(&call.host.mcp_windows(call.root()));
+    let (project, file) = (call.project.clone(), path.clone());
+    let text = call.host.blocking(move || project.text_of(&file)).await.unwrap_or_default();
+    let errors: Vec<_> = files
+        .into_iter()
+        .filter(|f| f.path.0 == path)
+        .flat_map(|f| f.items)
+        .filter(|d| !errors_only || d.severity == Severity::Error)
+        .map(|d| problem(d, &text))
+        .collect();
+    Output::json(json!({"filePath": call.display(&path), "errors": errors}))
+}
+
+async fn project_problems(call: Call) -> IdeResult<Output> {
+    let files = call.host.mcp_reports.problems(&call.host.mcp_windows(call.root()));
+    let files: Vec<_> = files.into_iter().map(|f| json!({
+        "filePath":call.display(&f.path.0), "problems": f.items.into_iter().map(|d| problem(d, "")).collect::<Vec<_>>()
+    })).collect();
+    Output::json(json!({"files":files}))
+}

crates/ide-host/src/mcp/files.rs

@@ -0,0 +1,280 @@
+// Ported from JetBrains intellij-community plugins/mcp-server (mcpserver.toolsets/src/general/ReadToolset.kt,
+// the list_directory_tree part of FileToolset.kt, src/com/intellij/mcpserver/util/fs.util.kt), Apache-2.0.
+//! Reading files and listing directories.
+
+use crate::mcp::tool::{Call, Output, Param, ParamType, Tool};
+use crate::mcp::util::{
+    self, RELATIVE_PATH_IN_PROJECT_DESCRIPTION, TIMED_OUT_DESCRIPTION, TIMEOUT_MILLISECONDS_DESCRIPTION,
+};
+use ide_core::{CancellationToken, IdeError, IdeResult};
+use serde::Serialize;
+use serde_json::json;
+use std::path::Path;
+use std::time::{Duration, Instant};
+
+const DEFAULT_READ_LIMIT: i64 = 2000;
+const MAX_READ_LIMIT: i64 = 5000;
+/// Longer lines are cut (minified files would flood the context), in UTF-16 units.
+const MAX_LINE_LENGTH: usize = 2000;
+const DEFAULT_TREE_DEPTH: i64 = 5;
+
+pub fn tools() -> Vec<Tool> {
+    vec![read_file(), list_directory_tree()]
+}
+
+// --- read_file -----------------------------------------------------------------
+
+fn read_file() -> Tool {
+    Tool::new(
+        "read_file",
+        "Reads a file in the project directory or from any project dependency or other project source root.
+Can read text sources inside jar/zip archives; compiled class files are not decompiled.
+Returns numbered lines (1-indexed) as text.
+By default, reads up to 2000 lines starting from the beginning of the file.
+The maximum accepted limit is 5000 lines.",
+        |call| async move {
+            let offset = positive(&call, "offset", 1)?;
+            let limit = positive(&call, "limit", DEFAULT_READ_LIMIT)?;
+            if limit > MAX_READ_LIMIT {
+                return Err(IdeError::invalid(format!("limit must be <= {MAX_READ_LIMIT}")));
+            }
+            let path = util::resolve_read_file(&call, &call.str("file_path")?).await?;
+            if call.project().documents.by_path(&path).is_none()
+                && let probe = ide_vfs::probe(&path)?
+                && probe.binary
+            {
+                return Err(IdeError::invalid(format!(
+                    "{} is a binary file ({} bytes); read_file reads text",
+                    call.display(&path),
+                    probe.size
+                )));
+            }
+            let text = crate::ops::fs::read_text(&call.host(), call.window(), path).await?;
+            Ok(Output::text(render_slice(&text, offset as usize, limit as usize)?))
+        },
+    )
+    .param(Param::required("file_path", ParamType::String, util::FILE_PATH_DESCRIPTION))
+    .param(Param::optional("offset", ParamType::Integer, "1-based line number to start reading from"))
+    .param(Param::optional(
+        "limit",
+        ParamType::Integer,
+        "Maximum number of lines to return (default: 2000, max: 5000)",
+    ))
+}
+
+/// An integer argument that must be > 0.
+fn positive(call: &Call, name: &str, default: i64) -> IdeResult<i64> {
+    match call.opt_i64(name)?.unwrap_or(default) {
+        n if n <= 0 => Err(IdeError::invalid(format!("{name} must be > 0"))),
+        n => Ok(n),
+    }
+}
+
+/// Lines `start..` of `text` as `L<n>: <line>`; when more than `max_lines` remain, the first
+/// and the last halves of the budget with a `…N lines truncated…` marker between them.
+/// Lines are the editor's: a trailing line break starts an empty last line.
+fn render_slice(text: &str, start: usize, max_lines: usize) -> IdeResult<String> {
+    let lines: Vec<&str> = text.split('\n').map(|l| l.strip_suffix('\r').unwrap_or(l)).collect();
+    let count = lines.len();
+    if start > count {
+        return Err(IdeError::invalid("offset exceeds file length"));
+    }
+    let range = |from: usize, to: usize| {
+        (from..=to).map(|n| format!("L{n}: {}", format_line(lines[n - 1]))).collect::<Vec<_>>().join("\n")
+    };
+    let available = count - start + 1;
+    if available <= max_lines {
+        return Ok(range(start, count));
+    }
+    let head = max_lines / 2;
+    let tail = max_lines - head;
+    let head_end = start + head - 1;
+    let tail_start = count - tail + 1;
+    let mut out = String::new();
+    if head > 0 {
+        out.push_str(&range(start, head_end));
+        out.push('\n');
+    }
+    out.push_str(&format!("\u{2026}{} lines truncated\u{2026}", tail_start - head_end - 1));
+    if tail > 0 {
+        out.push('\n');
+        out.push_str(&range(tail_start, count));
+    }
+    Ok(out)
+}
+
+/// `line` cut to [`MAX_LINE_LENGTH`] UTF-16 units, or as many characters when the cut would
+/// split a surrogate pair (as JetBrains does).
+fn format_line(line: &str) -> &str {
+    let mut units = 0;
+    for (i, c) in line.char_indices() {
+        if units >= MAX_LINE_LENGTH {
+            return &line[..i];
+        }
+        if units + c.len_utf16() > MAX_LINE_LENGTH {
+            // A pair across the boundary: keep MAX_LINE_LENGTH characters instead.
+            return match line.char_indices().nth(MAX_LINE_LENGTH) {
+                Some((cut, _)) => &line[..cut],
+                None => line,
+            };
+        }
+        units += c.len_utf16();
+    }
+    line
+}
+
+// --- list_directory_tree -------------------------------------------------------
+
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+struct DirectoryTreeInfo {
+    traversed_directory: String,
+    tree: String,
+    errors: Vec<String>,
+    #[serde(skip_serializing_if = "std::ops::Not::not")]
+    listing_timed_out: bool,
+}
+
+fn list_directory_tree() -> Tool {
+    Tool::new(
+        "list_directory_tree",
+        "Provides a tree representation of the specified directory in the pseudo graphic format like `tree` utility does.
+Use this tool to explore the contents of a directory or the whole project.
+You MUST prefer this tool over listing directories via command line utilities like `ls` or `dir`.",
+        |call| async move {
+            let directory = call.str("directoryPath")?;
+            let max_depth = call.opt_i64("maxDepth")?.unwrap_or(DEFAULT_TREE_DEPTH);
+            let timeout = call.opt_i64("timeout")?.unwrap_or(util::MEDIUM_TIMEOUT.as_millis() as i64);
+            let dir = call.resolve_readable(&directory).await?;
+            if !dir.exists() {
+                return Err(IdeError::not_found(format!("No such directory: {}", dir.display())));
+            }
+            if !dir.is_dir() {
+                return Err(IdeError::invalid(format!("Not a directory: {}", dir.display())));
+            }
+            let deadline = Instant::now() + Duration::from_millis(timeout.max(0) as u64);
+            let cancel = call.cancel.clone();
+            let mut tree =
+                TreeRender { out: String::new(), errors: Vec::new(), timed_out: false, deadline, cancel: cancel.clone() };
+            let tree = call
+                .host()
+                .blocking(move || {
+                    tree.render(&dir, "", true, max_depth, true);
+                    Ok(tree)
+                })
+                .await?;
+            if cancel.is_cancelled() {
+                return Err(IdeError::cancelled());
+            }
+            Output::json(DirectoryTreeInfo {
+                traversed_directory: directory,
+                tree: tree.out,
+                errors: tree.errors,
+                listing_timed_out: tree.timed_out,
+            })
+        },
+    )
+    .param(Param::required("directoryPath", ParamType::String, RELATIVE_PATH_IN_PROJECT_DESCRIPTION))
+    .param(Param::optional("maxDepth", ParamType::Integer, "Maximum recursion depth"))
+    .param(Param::optional("timeout", ParamType::Integer, TIMEOUT_MILLISECONDS_DESCRIPTION))
+    .output(json!({
+        "type": "object",
+        "properties": {
+            "traversedDirectory": { "type": "string" },
+            "tree": { "type": "string" },
+            "errors": { "type": "array", "items": { "type": "string" } },
+            "listingTimedOut": { "type": "boolean", "description": TIMED_OUT_DESCRIPTION },
+        },
+        "required": ["traversedDirectory", "tree", "errors"],
+    }))
+}
+
+/// The `tree`-like listing: the directory's absolute path, then every entry (hidden and
+/// ignored ones too) by lower-cased name, directories marked with `/`.
+struct TreeRender {
+    out: String,
+    errors: Vec<String>,
+    timed_out: bool,
+    deadline: Instant,
+    cancel: CancellationToken,
+}
+
+impl TreeRender {
+    fn render(&mut self, path: &Path, indent: &str, is_last: bool, max_depth: i64, is_root: bool) {
+        if max_depth <= 0 || self.timed_out || self.cancel.is_cancelled() {
+            return;
+        }
+        if Instant::now() >= self.deadline {
+            self.timed_out = true;
+            return;
+        }
+        let prefix = match (is_root, is_last) {
+            (true, _) => "",
+            (false, true) => "└── ",
+            (false, false) => "├── ",
+        };
+        let name = if is_root {
+            path.display().to_string()
+        } else {
+            path.file_name().unwrap_or_default().to_string_lossy().into_owned()
+        };
+        let is_dir = path.is_dir() && !path.is_symlink();
+        self.out.push_str(&format!("{indent}{prefix}{name}{}\n", if is_dir { "/" } else { "" }));
+        if !is_dir {
+            return;
+        }
+        let mut children: Vec<_> = match std::fs::read_dir(path) {
+            Ok(entries) => entries.filter_map(|e| e.ok().map(|e| e.path())).collect(),
+            Err(e) => {
+                self.errors.push(format!("Failed to read {}: {e}", path.display()));
+                return;
+            }
+        };
+        let key = |p: &std::path::PathBuf| p.file_name().unwrap_or_default().to_string_lossy().into_owned();
+        children.sort_by_cached_key(|p| (key(p).to_lowercase(), key(p)));
+        let child_indent = format!("{indent}{}", if is_last { "    " } else { "│   " });
+        let n = children.len();
+        for (i, child) in children.iter().enumerate() {
+            self.render(child, &child_indent, i + 1 == n, max_depth - 1, false);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn slice(text: &str, start: usize, max: usize) -> String {
+        render_slice(text, start, max).unwrap()
+    }
+
+    #[test]
+    fn numbers_lines_like_the_editor() {
+        assert_eq!(slice("a\nb", 1, 10), "L1: a\nL2: b");
+        assert_eq!(slice("a\r\nb\n", 1, 10), "L1: a\nL2: b\nL3: ");
+        assert_eq!(slice("", 1, 10), "L1: ");
+        assert_eq!(slice("a\nb\nc", 2, 10), "L2: b\nL3: c");
+        assert!(render_slice("", 2, 10).unwrap_err().message.contains("offset exceeds file length"));
+        assert!(render_slice("a\nb", 3, 10).unwrap_err().message.contains("offset exceeds file length"));
+    }
+
+    #[test]
+    fn keeps_head_and_tail_of_long_slices() {
+        let text = (1..=11).map(|n| format!("line {n}")).collect::<Vec<_>>().join("\n");
+        assert_eq!(slice(&text, 1, 4), "L1: line 1\nL2: line 2\n…7 lines truncated…\nL10: line 10\nL11: line 11");
+        assert_eq!(slice(&text, 3, 4), "L3: line 3\nL4: line 4\n…5 lines truncated…\nL10: line 10\nL11: line 11");
+        assert_eq!(slice(&text, 1, 1), "…10 lines truncated…\nL11: line 11");
+    }
+
+    #[test]
+    fn cuts_long_lines_at_utf16_units() {
+        let long = "x".repeat(2100);
+        assert_eq!(format_line(&long).len(), MAX_LINE_LENGTH);
+        // A pair across the boundary keeps 2000 characters.
+        let pair = format!("{}😀{}", "x".repeat(1999), "y".repeat(10));
+        assert_eq!(format_line(&pair).chars().count(), MAX_LINE_LENGTH);
+        assert!(format_line(&pair).ends_with('😀'));
+        let short = format!("{}😀", "x".repeat(1998));
+        assert_eq!(format_line(&short), short);
+    }
+}

crates/ide-host/src/mcp/mod.rs

@@ -0,0 +1,142 @@
+//! Built-in IDE tools. Transport and discovery live in `ide-mcp`.
+mod edit;
+mod editors;
+mod requests;
+mod run;
+mod vcs;
+pub use requests::Requests;
+mod files;
+mod reports;
+mod search;
+mod symbols;
+mod tool;
+mod util;
+
+use crate::Host;
+use ide_core::{CancellationToken, IdeError};
+use ide_mcp::{ToolCallError, ToolRegistry};
+pub use reports::{FileProblems, FocusedEditor, Reports};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+pub struct Registry(Arc<Host>);
+impl Registry {
+    pub fn new(host: Arc<Host>) -> Self {
+        Self(host)
+    }
+}
+
+fn tools() -> Vec<tool::Tool> {
+    let mut tools = files::tools();
+    tools.extend(search::tools());
+    tools.extend(editors::tools());
+    tools.push(symbols::get_symbol_info());
+    tools.push(symbols::find_references());
+    tools.extend(edit::tools());
+    tools.extend(run::tools());
+    tools.extend(vcs::tools());
+    tools
+}
+
+// Checked both when listing and calling, so a later trust change takes effect immediately.
+fn allowed(tool: &ide_mcp::Tool, trusted: bool) -> bool {
+    trusted || tool.read_only
+}
+
+impl Registry {
+    fn target(&self, root: &Path) -> Result<(String, Arc<crate::Project>), String> {
+        if self.0.mcp_reports.remote_roots().iter().any(|p| p == root) {
+            return Err("not supported for remote projects yet".into());
+        }
+        let mut windows: Vec<_> = self
+            .0
+            .projects
+            .read()
+            .iter()
+            .filter(|(_, p)| p.root == root && !p.light)
+            .map(|(w, p)| (w.clone(), p.clone()))
+            .collect();
+        let focused = self.0.mcp_reports.focused_window();
+        windows.sort_by(|a, b| {
+            (Some(&b.0) == focused.as_ref()).cmp(&(Some(&a.0) == focused.as_ref())).then(a.0.cmp(&b.0))
+        });
+        windows.into_iter().next().ok_or_else(|| "project is no longer open".into())
+    }
+}
+impl ToolRegistry for Registry {
+    fn projects(&self) -> Vec<PathBuf> {
+        self.0
+            .projects()
+            .into_iter()
+            .filter(|p| !p.light)
+            .map(|p| p.root.clone())
+            .chain(self.0.mcp_reports.remote_roots())
+            .collect()
+    }
+    fn tools(&self, root: &Path) -> Result<Vec<ide_mcp::Tool>, String> {
+        let (_, project) = self.target(root)?;
+        Ok(tools().into_iter().map(|t| t.metadata).filter(|t| allowed(t, project.is_trusted())).collect())
+    }
+    fn call(
+        &self,
+        root: &Path,
+        name: &str,
+        arguments: &str,
+        cancel: CancellationToken,
+    ) -> Result<String, ToolCallError> {
+        self.call_with_client(root, name, arguments, cancel, "MCP client")
+    }
+    fn call_with_client(
+        &self,
+        root: &Path,
+        name: &str,
+        arguments: &str,
+        cancel: CancellationToken,
+        client: &str,
+    ) -> Result<String, ToolCallError> {
+        let (window, project) = self.target(root).map_err(ToolCallError::Failed)?;
+        let tool = tools()
+            .into_iter()
+            .find(|t| t.metadata.name == name && allowed(&t.metadata, project.is_trusted()))
+            .ok_or_else(|| ToolCallError::UnknownTool(format!("unknown tool: {name}")))?;
+        let args = serde_json::from_str(arguments).map_err(|e| ToolCallError::Failed(e.to_string()))?;
+        let call = tool::Call {
+            host: self.0.clone(),
+            project,
+            window,
+            args,
+            cancel: cancel.clone(),
+            client: client.to_owned(),
+            tool: name.to_owned(),
+        };
+        if cancel.is_cancelled() {
+            return Err(ToolCallError::Failed(IdeError::cancelled().message));
+        }
+        let result = self.0.runtime.block_on((tool.handler)(call));
+        if cancel.is_cancelled() {
+            return Err(ToolCallError::Failed(IdeError::cancelled().message));
+        }
+        result.map(|out| out.0).map_err(|e| ToolCallError::Failed(e.message))
+    }
+}
+
+impl Host {
+    fn mcp_windows(&self, root: &Path) -> Vec<String> {
+        let mut windows: Vec<_> =
+            self.projects.read().iter().filter(|(_, p)| p.root == root).map(|(w, _)| w.clone()).collect();
+        windows.sort();
+        windows
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn restricted_mode_excludes_execution_tools() {
+        let mut tool = super::tools().remove(0).metadata;
+        assert!(super::allowed(&tool, false));
+        tool.read_only = false;
+        assert!(!super::allowed(&tool, false));
+        assert!(super::allowed(&tool, true));
+    }
+}

crates/ide-host/src/mcp/reports.rs

@@ -0,0 +1,124 @@
+//! Window-owned snapshots. A project close drops every report from that window.
+use ide_core::{Diagnostic, IpcPath, Range};
+use parking_lot::RwLock;
+use serde::{Deserialize, Serialize};
+use specta::Type;
+use std::collections::{BTreeMap, HashMap};
+use std::path::PathBuf;
+
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct FileProblems {
+    pub path: IpcPath,
+    pub items: Vec<Diagnostic>,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct FocusedEditor {
+    pub path: IpcPath,
+    /// Zero-based lines and UTF-16 columns, end exclusive.
+    pub selection: Range,
+    pub selected_text: String,
+}
+
+#[derive(Default)]
+pub struct Reports(RwLock<State>);
+#[derive(Default)]
+struct State {
+    windows: HashMap<String, Window>,
+    focused: Option<String>,
+    remote: HashMap<String, PathBuf>,
+    libraries: HashMap<String, Vec<PathBuf>>,
+}
+#[derive(Default)]
+struct Window {
+    editors: Vec<PathBuf>,
+    focused: Option<FocusedEditor>,
+    problems: BTreeMap<PathBuf, Vec<Diagnostic>>,
+}
+impl Reports {
+    pub fn set_open_editors(&self, window: &str, paths: Vec<PathBuf>) {
+        self.0.write().windows.entry(window.into()).or_default().editors = paths;
+    }
+    pub fn set_focused_editor(&self, window: &str, editor: Option<FocusedEditor>, focused: bool) {
+        let mut state = self.0.write();
+        state.windows.entry(window.into()).or_default().focused = editor;
+        if focused {
+            state.focused = Some(window.into());
+        }
+    }
+    pub fn report_problems(&self, window: &str, reset: bool, files: Vec<FileProblems>) {
+        let mut state = self.0.write();
+        let problems = &mut state.windows.entry(window.into()).or_default().problems;
+        if reset {
+            problems.clear();
+        }
+        for file in files {
+            let path = file.path.into();
+            if file.items.is_empty() {
+                problems.remove(&path);
+            } else {
+                problems.insert(path, file.items);
+            }
+        }
+    }
+    pub fn forget_window(&self, window: &str) {
+        let mut state = self.0.write();
+        state.windows.remove(window);
+        state.remote.remove(window);
+        state.libraries.remove(window);
+        if state.focused.as_deref() == Some(window) {
+            state.focused = None;
+        }
+    }
+    pub fn set_remote(&self, window: &str, root: PathBuf) {
+        self.0.write().remote.insert(window.into(), root);
+    }
+    pub fn remove_remote(&self, window: &str) {
+        self.0.write().remote.remove(window);
+    }
+    pub(crate) fn set_libraries(&self, window: &str, roots: Vec<PathBuf>) {
+        self.0.write().libraries.insert(window.into(), roots);
+    }
+    pub(super) fn libraries(&self, windows: &[String]) -> Vec<PathBuf> {
+        let state = self.0.read();
+        windows.iter().filter_map(|w| state.libraries.get(w)).flatten().cloned().collect()
+    }
+    pub(super) fn remote_roots(&self) -> Vec<PathBuf> {
+        self.0.read().remote.values().cloned().collect()
+    }
+    pub(super) fn focused_window(&self) -> Option<String> {
+        self.0.read().focused.clone()
+    }
+    pub(super) fn editors(&self, windows: &[String]) -> Vec<PathBuf> {
+        let state = self.0.read();
+        let mut paths = Vec::new();
+        for window in windows.iter().filter_map(|w| state.windows.get(w)) {
+            for path in &window.editors {
+                if !paths.contains(path) {
+                    paths.push(path.clone());
+                }
+            }
+        }
+        paths
+    }
+    pub(super) fn focused(&self, window: &str) -> Option<FocusedEditor> {
+        self.0.read().windows.get(window).and_then(|w| w.focused.clone())
+    }
+    pub(super) fn problems(&self, windows: &[String]) -> Vec<FileProblems> {
+        let state = self.0.read();
+        let mut files: BTreeMap<PathBuf, Vec<Diagnostic>> = BTreeMap::new();
+        for window in windows.iter().filter_map(|w| state.windows.get(w)) {
+            for (path, items) in &window.problems {
+                let found = files.entry(path.clone()).or_default();
+                for item in items {
+                    if !found.contains(item) {
+                        found.push(item.clone());
+                    }
+                }
+            }
+        }
+        files.into_iter().map(|(path, items)| FileProblems { path: path.into(), items }).collect()
+    }
+}

crates/ide-host/src/mcp/requests.rs

@@ -0,0 +1,71 @@
+//! Window-bound requests; missing windows, cancellation and timeout all fail closed.
+use super::tool::Call;
+use ide_core::{IdeError, IdeEvent, IdeResult, event::McpUiRequest};
+use parking_lot::Mutex;
+use std::collections::{HashMap, HashSet};
+use tokio::sync::oneshot;
+
+#[derive(Default)]
+pub struct Requests(Mutex<State>);
+#[derive(Default)]
+struct State {
+    ready: HashSet<String>,
+    pending: HashMap<u32, Pending>,
+}
+struct Pending {
+    window: String,
+    answer: oneshot::Sender<Result<bool, String>>,
+}
+impl Requests {
+    pub fn set_ready(&self, window: &str, ready: bool) {
+        if ready {
+            self.0.lock().ready.insert(window.into());
+        } else {
+            self.forget_window(window);
+        }
+    }
+    pub fn forget_window(&self, window: &str) {
+        let mut state = self.0.lock();
+        state.ready.remove(window);
+        state.pending.retain(|_, p| p.window != window);
+    }
+    pub fn answer(&self, window: &str, id: u32, allow: bool, error: Option<String>) -> IdeResult<()> {
+        let mut state = self.0.lock();
+        if !state.pending.get(&id).is_some_and(|p| p.window == window) {
+            return Err(IdeError::invalid("MCP request expired or belongs to another window"));
+        }
+        let pending = state.pending.remove(&id).unwrap();
+        let _ = pending.answer.send(error.map_or(Ok(allow), Err));
+        Ok(())
+    }
+    pub(super) async fn ask(&self, call: &Call, request: McpUiRequest) -> IdeResult<()> {
+        let id = super::tool::request_id().0;
+        let (tx, rx) = oneshot::channel();
+        {
+            let mut state = self.0.lock();
+            if !state.ready.contains(call.window()) {
+                return Err(IdeError::unavailable("MCP request denied: no project window is available"));
+            }
+            state.pending.insert(id, Pending { window: call.window.clone(), answer: tx });
+        }
+        struct Close<'a>(&'a Requests, &'a Call, u32);
+        impl Drop for Close<'_> {
+            fn drop(&mut self) {
+                self.0.0.lock().pending.remove(&self.2);
+                self.1.project.sink.emit(IdeEvent::McpRequestClosed { id: self.2 });
+            }
+        }
+        let _close = Close(self, call, id);
+        call.project.sink.emit(IdeEvent::McpRequest { id, request });
+        let result = tokio::select! {
+            result = rx => result.map_err(|_| IdeError::unavailable("MCP request denied: project window closed"))?,
+            _ = tokio::time::sleep(std::time::Duration::from_secs(180)) => return Err(IdeError::unavailable("MCP request denied: confirmation timed out")),
+            _ = call.cancel.cancelled() => return Err(IdeError::cancelled()),
+        };
+        match result {
+            Ok(true) => Ok(()),
+            Ok(false) => Err(IdeError::invalid("MCP request denied by the user")),
+            Err(message) => Err(IdeError::unavailable(message)),
+        }
+    }
+}

crates/ide-host/src/mcp/run/build.rs

@@ -0,0 +1,214 @@
+// Ported from JetBrains intellij-community plugins/mcp-server
+// (mcpserver.toolsets/src/general/AnalysisToolset.kt, build_project), Apache-2.0.
+//! `build_project`.
+
+use super::output::{MAX_TEXT_LENGTH, TRUNCATED_MARKER, truncate_tail};
+use crate::mcp::run::timeout;
+use crate::mcp::tool::{Call, Output, Param, ParamType, Tool};
+use ide_build::compile::{BuildEvent, BuildKind, BuildMessage, BuildResult};
+use ide_core::Severity;
+use ide_core::{IdeError, IdeResult};
+use parking_lot::Mutex;
+use serde_json::{Map, Value, json};
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::time::Instant;
+
+const DEFAULT_TIMEOUT_MS: usize = 60_000;
+const MAX_TIMEOUT_MS: usize = 3_600_000;
+const MAX_PROBLEMS: usize = 300;
+/// Console lines attached to a failure whose messages were not parsed.
+const CONSOLE_LINES: usize = 200;
+
+/// A JetBrains `ProjectProblem`: `kind` ERROR or WARNING, the compiler's code as `group`,
+/// 1-based `line` / `column` (JetBrains reports them 0-based).
+fn problem(call: &Call, m: &BuildMessage) -> Value {
+    let mut v = json!({
+        "message": m.text,
+        "kind": if m.severity == Severity::Error { "ERROR" } else { "WARNING" },
+    });
+    if let Some(code) = &m.code {
+        v["group"] = code.clone().into();
+    }
+    if let Some(path) = &m.path {
+        v["file"] = call.display(path).into();
+    }
+    if let Some(range) = m.range {
+        v["line"] = (range.start.line + 1).into();
+        v["column"] = (range.start.col + 1).into();
+    }
+    v
+}
+
+/// Runs the build of `target` (the whole project when `None`), its console into `console`.
+/// Returns `None` when `deadline` passed first (the build is then stopped).
+pub async fn build_once(
+    call: &Call,
+    kind: BuildKind,
+    target: Option<PathBuf>,
+    deadline: Instant,
+    console: &Arc<Mutex<String>>,
+) -> IdeResult<Option<BuildResult>> {
+    let host = call.host();
+    let request = crate::mcp::tool::request_id();
+    let sink = console.clone();
+    let channel = crate::ops::Channel::new(move |e: BuildEvent| match e {
+        BuildEvent::Output { text, .. } => sink.lock().push_str(&text),
+        BuildEvent::Step { command, .. } => sink.lock().push_str(&format!("$ {command}\n")),
+        _ => {}
+    });
+    let build = crate::ops::build::build_run(&host, call.window(), kind, target, None, request, Vec::new(), channel);
+    tokio::pin!(build);
+    let remaining = deadline.saturating_duration_since(Instant::now());
+    tokio::select! {
+        r = &mut build => r.map(Some),
+        _ = tokio::time::sleep(remaining) => {
+            host.cancel_request(request);
+            let _ = build.await;
+            Ok(None)
+        }
+        _ = call.cancel.cancelled() => {
+            host.cancel_request(request);
+            let _ = build.await;
+            Err(IdeError::cancelled())
+        }
+    }
+}
+
+pub fn build_project() -> Tool {
+    Tool::new(
+        "build_project",
+        "Triggers building of the project or specified files, waits for completion, and returns build errors.
+Use this tool to build the project or compile files and get detailed information about compilation errors and warnings.
+You have to use this tool after performing edits to validate if the edits are valid.
+In OpenIDEA the project's build system builds it (Maven, Gradle, Cargo, Go or TypeScript); with `filesToRebuild`, the \
+modules containing those files. Asks the user first for every call. Problems have the project-relative \
+`file` and 1-based `line` / `column`; at most 300 problems are listed, and `isSuccess` is false whenever one of them \
+is an ERROR. On timeout (at most 1 hour; 0 times out at once) the build is stopped.",
+        |call| async move {
+            let files: Vec<String> =
+                call.str_list("filesToRebuild")?.into_iter().filter(|f| !f.trim().is_empty()).collect();
+            let rebuild = call.flag("rebuild", false)? && files.is_empty();
+            let kind = if rebuild { BuildKind::Rebuild } else { BuildKind::Build };
+            let limit = timeout(&call, DEFAULT_TIMEOUT_MS, MAX_TIMEOUT_MS)?;
+            let mut targets: Vec<Option<PathBuf>> = Vec::new();
+            let mut dirs: Vec<PathBuf> = Vec::new();
+            for f in &files {
+                let path = call.resolve_inside(f)?;
+                if !path.exists() {
+                    return Err(IdeError::not_found(format!("File not found: {f}")));
+                }
+                let dir = if path.is_dir() { path.clone() } else { path.parent().unwrap_or(&path).to_path_buf() };
+                if !dirs.contains(&dir) {
+                    dirs.push(dir);
+                    targets.push(Some(path));
+                }
+            }
+            if targets.is_empty() {
+                targets.push(None);
+            }
+            let subject = if rebuild { "Rebuild project" } else { "Build project" };
+            let detail = targets.iter().flatten().map(|p| call.display(p)).collect::<Vec<_>>().join(", ");
+            call.confirm(subject, (!detail.is_empty()).then(|| format!("modules of {detail}"))).await?;
+
+            if limit.is_zero() {
+                // JetBrains' `withTimeoutOrNull(0)`: nothing is built.
+                return Output::json(json!({ "isSuccess": false, "problems": [], "timedOut": true }));
+            }
+            let console = Arc::new(Mutex::new(String::new()));
+            let deadline = Instant::now() + limit;
+            let mut results: Vec<BuildResult> = Vec::new();
+            let mut timed_out = false;
+            for target in targets {
+                match build_once(&call, kind, target, deadline, &console).await? {
+                    Some(r) => {
+                        let failed = !r.success;
+                        results.push(r);
+                        if failed {
+                            break;
+                        }
+                    }
+                    None => {
+                        timed_out = true;
+                        break;
+                    }
+                }
+            }
+            let messages: Vec<&BuildMessage> = results
+                .iter()
+                .flat_map(|r| r.messages.iter())
+                .filter(|m| matches!(m.severity, Severity::Error | Severity::Warning))
+                .collect();
+            let mut problems: Vec<Value> = messages.iter().take(MAX_PROBLEMS).map(|m| problem(&call, m)).collect();
+            let has_errors = messages.iter().any(|m| m.severity == Severity::Error);
+            let failed = results.iter().any(|r| !r.success);
+            if failed && !has_errors {
+                let tail = truncate_tail(
+                    console.lock().trim_end(),
+                    CONSOLE_LINES,
+                    MAX_TEXT_LENGTH,
+                    TRUNCATED_MARKER,
+                );
+                problems.push(json!({
+                    "message": "Build reported errors, but detailed error messages were not captured through build events.",
+                    "kind": "ERROR",
+                    "description": tail,
+                }));
+            }
+            let mut result = Map::new();
+            result.insert("isSuccess".into(), is_success(timed_out, &results).into());
+            result.insert("problems".into(), problems.into());
+            if timed_out {
+                result.insert("timedOut".into(), true.into());
+            }
+            Output::json(Value::Object(result))
+        },
+    )
+    .write()
+    .param(Param::optional(
+        "rebuild",
+        ParamType::Boolean,
+        "Whether to perform full rebuild the project. Defaults to false. Effective only when `filesToRebuild` is not \
+specified.",
+    ))
+    .param(Param::optional(
+        "filesToRebuild",
+        ParamType::StringList,
+        "If specified, only compile files with the specified paths. Paths are relative to the project root.",
+    ))
+    .param(Param::optional("timeout", ParamType::Integer, "Timeout in milliseconds"))
+}
+
+/// JetBrains' `isSuccess`: finished in time, every build succeeded and no ERROR was reported
+/// (a build tool may exit 0 after printing errors).
+fn is_success(timed_out: bool, results: &[BuildResult]) -> bool {
+    !timed_out && results.iter().all(|r| r.success && r.messages.iter().all(|m| m.severity != Severity::Error))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn result(success: bool, severities: &[Severity]) -> BuildResult {
+        BuildResult {
+            system: ide_build::compile::BuildSystem::Cargo,
+            title: "build".into(),
+            success,
+            errors: 0,
+            warnings: 0,
+            duration_ms: 0.0,
+            messages: severities
+                .iter()
+                .map(|s| BuildMessage { severity: *s, text: "m".into(), path: None, range: None, code: None })
+                .collect(),
+        }
+    }
+
+    #[test]
+    fn an_error_problem_fails_the_build() {
+        assert!(is_success(false, &[result(true, &[Severity::Warning])]));
+        assert!(!is_success(false, &[result(true, &[Severity::Warning, Severity::Error])]));
+        assert!(!is_success(false, &[result(false, &[])]));
+        assert!(!is_success(true, &[result(true, &[])]));
+    }
+}

crates/ide-host/src/mcp/run/configs.rs

@@ -0,0 +1,709 @@
+// Ported from JetBrains intellij-community plugins/mcp-server (mcpserver.toolsets/src/general/ExecutionToolset.kt,
+// mcpserver.toolsets/src/util/execution.util.kt, mcpserver.toolsets/src/util/RunConfigurationBuildErrors.kt), Apache-2.0.
+//! `get_run_configurations` and `execute_run_configuration`.
+
+use super::build::build_once;
+use super::output::OutputCollector;
+use super::process::{quote, split_words};
+use super::targets;
+use crate::Project;
+use crate::mcp::run::timeout;
+use crate::mcp::tool::{Call, Output, Param, ParamType, Tool};
+use ide_build::compile::BuildKind;
+use ide_core::{IdeError, IdeResult, RunId, Severity};
+use ide_run::{OutputChunk, RunConfig};
+use parking_lot::Mutex;
+use serde_json::{Map, Value, json};
+use std::path::Path;
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+
+const DEFAULT_TIMEOUT_MS: usize = 10_000;
+/// No limit in JetBrains; the process keeps running after the timeout anyway.
+const MAX_TIMEOUT_MS: usize = 1_800_000;
+/// Output of a failed before-launch process kept for the error message.
+const MAX_PROCESS_OUTPUT_LENGTH: usize = 20_000;
+/// A before-launch build gets this long.
+const BEFORE_LAUNCH_BUILD_TIMEOUT: Duration = Duration::from_secs(3600);
+
+async fn load_configs(call: &Call) -> IdeResult<Vec<RunConfig>> {
+    let host = call.host();
+    let window = call.window().to_owned();
+    let h = host.clone();
+    host.blocking(move || crate::ops::run::configs(&h, &window)).await
+}
+
+fn supports_overrides(config: &RunConfig) -> bool {
+    config.extras.compound.is_empty() && !config.command.trim().is_empty()
+}
+
+fn command_line(config: &RunConfig) -> String {
+    std::iter::once(config.command.clone()).chain(config.args.iter().map(|a| quote(a))).collect::<Vec<_>>().join(" ")
+}
+
+fn describe_config(call: &Call, c: &RunConfig) -> Value {
+    let mut v = json!({
+        "name": c.name,
+        "description": c.kind,
+        "supportsDynamicLaunchOverrides": supports_overrides(c),
+    });
+    if supports_overrides(c) {
+        v["commandLine"] = command_line(c).into();
+        if let Some(cwd) = c.cwd.as_deref() {
+            v["workingDirectory"] = call.display(&call.root().join(cwd)).into();
+        }
+        if !c.env.is_empty() {
+            v["environment"] = json!(c.env);
+        }
+    }
+    v
+}
+
+/// A file of the project to look for run points in: its `/`-separated project-relative path
+/// and current text (unsaved edits included).
+fn read_file(project: &Project, path: &Path, file: &str) -> IdeResult<(String, String)> {
+    let meta = std::fs::metadata(path).map_err(|_| IdeError::not_found(format!("File not found: {file}")))?;
+    if !meta.is_file() {
+        return Err(IdeError::invalid(format!("Not a file: {file}")));
+    }
+    let rel = path.strip_prefix(&project.root).unwrap_or(path).to_string_lossy().replace('\\', "/");
+    let text = match project.documents.text_of(path) {
+        Some(text) => text,
+        None => std::fs::read_to_string(path).map_err(|e| IdeError::invalid(format!("Cannot read {file}: {e}")))?,
+    };
+    Ok((rel, text))
+}
+
+/// Reads `file` and runs `scan` (root, relative path, text) over it off the async threads:
+/// the run point patterns go over up to 400 KB of text.
+async fn scan_file<T: Send + 'static>(
+    call: &Call,
+    file: &str,
+    scan: impl FnOnce(&Path, &str, &str) -> IdeResult<T> + Send + 'static,
+) -> IdeResult<T> {
+    let path = call.resolve_inside(file)?;
+    let project = call.project().clone();
+    let file = file.to_owned();
+    call.host()
+        .blocking(move || {
+            let (rel, text) = read_file(&project, &path, &file)?;
+            scan(&project.root, &rel, &text)
+        })
+        .await
+}
+
+pub fn get_run_configurations() -> Tool {
+    Tool::new(
+        "get_run_configurations",
+        "Returns either project run configurations or executable code locations, depending on the input.
+
+Without `filePath`, this tool lists the project's existing run configurations. The result includes configuration
+names and, when available, launch details such as program arguments, working directory, environment variables,
+and `supportsDynamicLaunchOverrides`.
+
+`supportsDynamicLaunchOverrides` is the source-of-truth capability flag for one-time launch overrides
+(`programArguments`, `workingDirectory`, `envs`) in `execute_run_configuration` and `xdebug_start_debugger_session`.
+Only pass those override parameters when this flag is `true` for the selected configuration.
+
+With `filePath`, this tool discovers executable entry points (run points) in that file, such as test methods,
+main methods, or other executable entry points where the IDE shows a Run gutter icon. The result contains `filePath` and
+`runPoints`; use the returned line numbers with `execute_run_configuration` to run from code.
+In OpenIDEA the configurations are the saved ones and those detected from the build files (package.json scripts, \
+Cargo targets, Gradle/Maven tasks, Go, Python, Makefile…); `description` is the configuration type and `commandLine` \
+the whole command. Run points are found in Rust, JavaScript/TypeScript, Python and Go files.",
+        |call| async move {
+            let configs = load_configs(&call).await?;
+            if let Some(file) = call.opt_str("filePath")? {
+                let points = scan_file(&call, &file, move |root, rel, text| {
+                    let mut points: Vec<Value> = Vec::new();
+                    let mut lines = std::collections::HashSet::new();
+                    for t in targets::detect(text, rel) {
+                        if lines.contains(&t.line) {
+                            continue;
+                        }
+                        if let Some(config) = targets::target_config(root, &t, rel, &configs, text) {
+                            lines.insert(t.line);
+                            points.push(json!({
+                                "line": t.line + 1,
+                                "description": format!("Run '{}'", config.name),
+                                "elementText": t.name,
+                            }));
+                        }
+                    }
+                    Ok(points)
+                })
+                .await?;
+                return Output::json(json!({ "filePath": file, "runPoints": points }));
+            }
+            let list: Vec<Value> = configs.iter().map(|c| describe_config(&call, c)).collect();
+            Output::json(json!({ "configurations": list }))
+        },
+    )
+    .write()
+    .param(Param::optional(
+        "filePath",
+        ParamType::String,
+        "Optional file path relative to the project root. When provided, returns run points (executable entry points) \
+in the file instead of project-wide run configurations.",
+    ))
+}
+
+/// What `execute_run_configuration` runs.
+enum ExecutionTarget {
+    ByName(String),
+    ByContext(String, i64),
+}
+
+fn execution_target(name: Option<String>, file: Option<String>, line: Option<i64>) -> IdeResult<ExecutionTarget> {
+    let name = name.filter(|n| !n.trim().is_empty());
+    let file = file.filter(|f| !f.trim().is_empty());
+    match (name, file, line) {
+        (Some(_), f, l) if f.is_some() || l.is_some() => {
+            Err(IdeError::invalid("Pass either configurationName or filePath + line, but not both."))
+        }
+        (Some(name), _, _) => Ok(ExecutionTarget::ByName(name)),
+        (None, Some(file), Some(line)) => Ok(ExecutionTarget::ByContext(file, line)),
+        (None, Some(_), None) | (None, None, Some(_)) => {
+            Err(IdeError::invalid("Pass both filePath and line together, or use configurationName."))
+        }
+        (None, None, None) => Err(IdeError::invalid("Pass either configurationName or filePath + line.")),
+    }
+}
+
+/// The temporary configuration of the run point at `file:line` (1-based): the innermost target
+/// enclosing that line (as JetBrains walks up to the enclosing test), else the whole file's
+/// (its tests, its main function).
+async fn config_from_code_location(
+    call: &Call,
+    configs: Vec<RunConfig>,
+    file: &str,
+    line: i64,
+) -> IdeResult<RunConfig> {
+    let file_name = file.to_owned();
+    scan_file(call, file, move |root, rel, text| {
+        if line < 1 {
+            return Err(IdeError::invalid(format!("Line number must be >= 1, got: {line}")));
+        }
+        let count = text.split('\n').count();
+        if line as usize > count {
+            return Err(IdeError::invalid(format!("Line {line} is out of range (file has {count} lines)")));
+        }
+        targets::enclosing(text, rel, line as usize - 1)
+            .iter()
+            .find_map(|t| targets::target_config(root, t, rel, &configs, text))
+            .or_else(|| targets::context_config(root, rel, &configs, text))
+            .ok_or_else(|| {
+                IdeError::not_found(format!(
+                    "No run configuration could be created from {file_name}:{line}. Use get_run_configurations with \
+filePath to find valid run locations."
+                ))
+            })
+    })
+    .await
+}
+
+/// Applies the one-off overrides (JetBrains' `prepareRunConfigurationForExecution`): a missing or
+/// empty string keeps the value, a whitespace-only one clears it; `envs` merge over the configuration's.
+fn apply_overrides(
+    config: &mut RunConfig,
+    root: &Path,
+    args: Option<String>,
+    cwd: Option<String>,
+    envs: Option<Vec<(String, String)>>,
+) -> IdeResult<()> {
+    let args = args.filter(|a| !a.is_empty());
+    let cwd = cwd.filter(|d| !d.is_empty());
+    if args.is_none() && cwd.is_none() && envs.is_none() {
+        return Ok(());
+    }
+    if !supports_overrides(config) {
+        return Err(IdeError::invalid(format!(
+            "Run configuration '{}' of type '{}' doesn't support dynamic launch overrides (programArguments, \
+workingDirectory, envs).",
+            config.name,
+            if config.extras.compound.is_empty() { config.kind.as_str() } else { "Compound" }
+        )));
+    }
+    if let Some(args) = args {
+        let words = split_words(&args)?;
+        // A configuration that is one shell line (`npm run dev`, no separate arguments)
+        // keeps its command and gets the new line's arguments appended.
+        let shell_line = config.args.is_empty() && config.command.trim().contains(char::is_whitespace);
+        if shell_line {
+            if !words.is_empty() {
+                config.command = format!("{} {}", config.command.trim(), args.trim());
+            }
+        } else {
+            config.args = words;
+        }
+    }
+    if let Some(dir) = cwd {
+        if dir.trim().is_empty() {
+            config.cwd = None;
+        } else {
+            let path = crate::mcp::tool::resolve_inside(root, &dir)?;
+            if !path.is_dir() {
+                return Err(IdeError::not_found(format!("workingDirectory {} is not a directory", path.display())));
+            }
+            config.cwd = Some(path.into());
+        }
+    }
+    config.env.extend(envs.into_iter().flatten());
+    Ok(())
+}
+
+/// Polls how run `id` ended: `None` while running, else its exit code (if known).
+fn run_exit(host: &crate::Host, id: RunId) -> Option<Option<i32>> {
+    match host.processes.exit_code(id) {
+        Ok(exit) => exit,
+        // Remote (SSH) runs, or a finished run already forgotten: the run list knows whether it runs.
+        Err(_) => match crate::ops::run::list(host).into_iter().find(|r| r.id == id) {
+            Some(r) if r.running => None,
+            _ => Some(None),
+        },
+    }
+}
+
+/// Waits for run `id` to exit, until `deadline`: `None` when it is still running. Cancelling
+/// the call stops the run.
+async fn wait_exit(call: &Call, id: RunId, deadline: Option<Instant>) -> IdeResult<Option<Option<i32>>> {
+    let host = call.host();
+    loop {
+        if let Some(exit) = run_exit(&host, id) {
+            return Ok(Some(exit));
+        }
+        if deadline.is_some_and(|d| Instant::now() >= d) {
+            return Ok(None);
+        }
+        tokio::select! {
+            _ = tokio::time::sleep(Duration::from_millis(50)) => {}
+            _ = call.cancel.cancelled() => {
+                let _ = crate::ops::run::stop(&host, call.window(), id);
+                return Err(IdeError::cancelled());
+            }
+        }
+    }
+}
+
+/// An output callback that skips the IDE's own lines (`Process finished…`), as JetBrains
+/// skips `ProcessOutputType.SYSTEM`.
+fn process_output(mut f: impl FnMut(&str) + Send + 'static) -> crate::ops::Emit<OutputChunk> {
+    let f = Mutex::new(move |t: &str| f(t));
+    Arc::new(move |chunk: OutputChunk| match &chunk {
+        OutputChunk::Stdout { text } | OutputChunk::Stderr { text } => (f.lock())(text),
+        OutputChunk::System { .. } => {}
+    })
+}
+
+/// What failed before launch (JetBrains' `RunConfigurationBuildErrors`): build errors as
+/// `path:line: message`, else the output of before-launch processes that failed.
+#[derive(Default)]
+struct BuildErrors {
+    errors: Vec<String>,
+    process_outputs: Vec<String>,
+}
+
+impl BuildErrors {
+    fn text(&self) -> Option<String> {
+        let mut seen = std::collections::HashSet::new();
+        let errors: Vec<&String> = self.errors.iter().filter(|e| seen.insert(*e)).collect();
+        if !errors.is_empty() {
+            return Some(errors.iter().map(|e| e.as_str()).collect::<Vec<_>>().join("\n"));
+        }
+        let outputs: Vec<&str> = self.process_outputs.iter().map(|o| o.trim()).filter(|o| !o.is_empty()).collect();
+        (!outputs.is_empty()).then(|| outputs.join("\n"))
+    }
+}
+
+/// Runs `config` to its end; `Ok(false)` (with its output recorded) when it failed.
+async fn run_to_end(call: &Call, config: RunConfig, errors: &mut BuildErrors) -> IdeResult<bool> {
+    let tail = Arc::new(Mutex::new(String::new()));
+    let sink = tail.clone();
+    let emit = process_output(move |text| {
+        let mut t = sink.lock();
+        t.push_str(text);
+        if t.len() > 2 * MAX_PROCESS_OUTPUT_LENGTH {
+            let mut cut = t.len() - MAX_PROCESS_OUTPUT_LENGTH;
+            while !t.is_char_boundary(cut) {
+                cut += 1;
+            }
+            t.drain(..cut);
+        }
+    });
+    let info = crate::ops::run::start(&call.host(), call.window(), config, emit).await?;
+    let exit = wait_exit(call, info.id, None).await?.flatten();
+    if exit == Some(0) {
+        return Ok(true);
+    }
+    let t = tail.lock();
+    let start = t.char_indices().rev().nth(MAX_PROCESS_OUTPUT_LENGTH - 1).map_or(0, |(i, _)| i);
+    errors.process_outputs.push(t[start..].to_owned());
+    Ok(false)
+}
+
+/// The configuration's before-launch tasks, as the Run tool window runs them; returns why
+/// the launch is aborted, if it is. Tool windows are not activated.
+async fn before_launch(
+    call: &Call,
+    config: &RunConfig,
+    configs: &[RunConfig],
+    chain: &mut Vec<String>,
+    errors: &mut BuildErrors,
+) -> IdeResult<Option<String>> {
+    chain.push(config.id.clone());
+    for task in &config.extras.before_launch {
+        let target = task.target.as_str();
+        let (label, failure) = match task.kind.as_str() {
+            "build" => {
+                let console = Arc::new(Mutex::new(String::new()));
+                let deadline = Instant::now() + BEFORE_LAUNCH_BUILD_TIMEOUT;
+                let failure = match build_once(call, BuildKind::Build, None, deadline, &console).await {
+                    Ok(Some(r)) => {
+                        for m in r.messages.iter().filter(|m| m.severity == Severity::Error) {
+                            errors.errors.push(match (&m.path, m.range) {
+                                (Some(p), Some(r)) => format!("{}:{}: {}", p.display(), r.start.line + 1, m.text),
+                                _ => m.text.clone(),
+                            });
+                        }
+                        (!r.success).then(|| "Build failed".to_owned())
+                    }
+                    Ok(None) => Some("The build timed out".to_owned()),
+                    Err(e) => Some(e.message),
+                };
+                ("Build Project".to_owned(), failure)
+            }
+            "run" => {
+                let other = configs.iter().find(|c| c.id == target);
+                let label = format!("Run '{}'", other.map_or(target, |c| c.name.as_str()));
+                let failure = if chain.iter().any(|c| c == target) {
+                    Some("The before launch tasks run in a cycle".to_owned())
+                } else if let Some(other) = other {
+                    let ok = Box::pin(before_launch(call, other, configs, chain, errors)).await?.is_none()
+                        && run_to_end(call, other.clone(), errors).await?;
+                    (!ok).then(|| format!("'{}' failed", other.name))
+                } else {
+                    Some(format!("Configuration '{target}' no longer exists"))
+                };
+                (label, failure)
+            }
+            "command" => {
+                let failure = if target.trim().is_empty() {
+                    Some("No command".to_owned())
+                } else {
+                    let run = RunConfig {
+                        id: format!("before-launch:{}:{target}", config.id),
+                        name: target.to_owned(),
+                        kind: "shell".into(),
+                        command: target.to_owned(),
+                        args: Vec::new(),
+                        cwd: config.cwd.clone(),
+                        env: Default::default(),
+                        detected: true,
+                        is_test: false,
+                        debug_adapter: None,
+                        allow_parallel: false,
+                        extras: Default::default(),
+                    };
+                    (!run_to_end(call, run, errors).await?).then(|| format!("'{target}' failed"))
+                };
+                (format!("Run '{target}'"), failure)
+            }
+            "toolWindow" => continue,
+            "tool" => (format!("External tool '{target}'"), Some("External tools cannot run through MCP".to_owned())),
+            other => (other.to_owned(), Some(format!("Unknown before launch task '{other}'"))),
+        };
+        if let Some(failure) = failure {
+            chain.pop();
+            return Ok(Some(format!("Before launch: {label}: {failure}")));
+        }
+    }
+    chain.pop();
+    Ok(None)
+}
+
+/// The before-launch tasks of `config` as the confirmation lists them, nested ones indented.
+fn describe_before_launch(
+    config: &RunConfig,
+    configs: &[RunConfig],
+    depth: usize,
+    chain: &mut Vec<String>,
+    out: &mut String,
+) {
+    chain.push(config.id.clone());
+    let indent = "  ".repeat(depth + 1);
+    for task in &config.extras.before_launch {
+        let target = task.target.as_str();
+        match task.kind.as_str() {
+            "build" => out.push_str(&format!("\n{indent}Build Project")),
+            "command" => out.push_str(&format!("\n{indent}Run command: {target}")),
+            "run" => match configs.iter().find(|c| c.id == target) {
+                Some(other) => {
+                    let line = if other.extras.compound.is_empty() { command_line(other) } else { "compound".into() };
+                    out.push_str(&format!("\n{indent}Run '{}': {line}", other.name));
+                    if !chain.contains(&other.id) {
+                        describe_before_launch(other, configs, depth + 1, chain, out);
+                    }
+                }
+                None => out.push_str(&format!("\n{indent}Run '{target}' (missing)")),
+            },
+            "toolWindow" => {}
+            "tool" => out.push_str(&format!("\n{indent}External tool '{target}'")),
+            other => out.push_str(&format!("\n{indent}{other} '{target}'")),
+        }
+    }
+    chain.pop();
+}
+
+/// What the user approves for `config` besides its command line: everything else that runs
+/// or applies — before-launch tasks, the stored environment (for a configuration made from
+/// code, the one of the configuration it derives from), `.env` files, the `envs` overrides
+/// (`NODE_OPTIONS`, `PATH`, ...), the stop command and a remote run target.
+fn confirmation_detail(
+    config: &RunConfig,
+    cwd: &str,
+    stored_env: &std::collections::BTreeMap<String, String>,
+    overrides: &[(String, String)],
+    configs: &[RunConfig],
+) -> String {
+    let mut detail = command_line(config);
+    if !cwd.is_empty() {
+        detail.push_str(&format!("\nin {cwd}"));
+    }
+    if let Some(target) = config.extras.target.as_deref().filter(|t| !t.is_empty()) {
+        detail.push_str(&format!("\non run target {target}"));
+    }
+    let mut tasks = String::new();
+    describe_before_launch(config, configs, 0, &mut Vec::new(), &mut tasks);
+    if !tasks.is_empty() {
+        detail.push_str(&format!("\nbefore launch:{tasks}"));
+    }
+    if !config.extras.env_files.is_empty() {
+        detail.push_str(&format!("\nenv files: {}", config.extras.env_files.join(", ")));
+    }
+    if !config.extras.include_system_env {
+        detail.push_str("\nwithout the system environment");
+    }
+    if !stored_env.is_empty() {
+        detail.push_str("\nenvironment:");
+        for (k, v) in stored_env {
+            detail.push_str(&format!("\n  {k}={v}"));
+        }
+    }
+    if !overrides.is_empty() {
+        detail.push_str("\nenvironment overrides:");
+        for (k, v) in overrides {
+            detail.push_str(&format!("\n  {k}={v}"));
+        }
+    }
+    if let Some(stop) = config.extras.stop_command.as_deref().filter(|s| !s.trim().is_empty()) {
+        detail.push_str(&format!("\non stop: {stop}"));
+    }
+    detail
+}
+
+fn execution_failed(details: &[Option<String>]) -> IdeError {
+    let details: Vec<&str> = details.iter().flatten().map(String::as_str).collect();
+    IdeError::invalid(format!("Execution failed: {}", details.join("\n")))
+}
+
+pub fn execute_run_configuration() -> Tool {
+    Tool::new(
+        "execute_run_configuration",
+        "Run either an existing run configuration by name or a temporary run configuration created from a code location \
+(`filePath` + `line`) in the current project, then wait up to specified timeout for it to finish.
+
+Use this tool with either a configuration name returned by `get_run_configurations`, or with a run point
+(`filePath` + `line`) returned by `get_run_configurations(filePath = ...)`.
+
+Optional launch overrides (`programArguments`, `workingDirectory`, `envs`) are applied only for this run and are not persisted.
+Do not pass these override parameters unless you explicitly need to change the configured launch values for this run.
+Missing/null override parameters keep existing run configuration values unchanged.
+For string overrides (`programArguments`, `workingDirectory`), missing/null or empty string (`\"\"`) keeps the existing value unchanged.
+Pass a whitespace-only string such as `\" \"` to clear an existing value for this launch.
+
+Pass either `configurationName`, or `filePath` together with `line`. These modes are mutually exclusive.
+
+Behavior:
+- When `waitForExit=true`, waits up to `timeout` milliseconds for process termination. If the timeout expires,
+  the process keeps running in the background and `exitCode` is omitted from the result.
+- When `waitForExit=false`, waits only for the process to start, then returns immediately without applying `timeout`.
+- `fullOutputPath` points to a temp file with the full raw output and may continue growing while the process is alive.
+
+Returns the execution result including current output snapshot, optional exit code, and optional `fullOutputPath`.
+In OpenIDEA the user is asked first for every call; `programArguments` replace the configuration's \
+arguments (appended to a command that is one shell line, such as `npm run dev`); the run does not appear in the Run \
+tool window; output files are private and deleted after a day.",
+        |call| async move {
+            let target = execution_target(
+                call.opt_str("configurationName")?,
+                call.opt_str("filePath")?,
+                call.opt_i64("line")?,
+            )?;
+            let wait = call.flag("waitForExit", true)?;
+            // As JetBrains: `timeout` is ignored without waiting, and 0 returns without waiting.
+            let limit = if wait { Some(timeout(&call, DEFAULT_TIMEOUT_MS, MAX_TIMEOUT_MS)?) } else { None };
+            let envs = call.args.get("envs").filter(|v| !v.is_null()).map(|_| call.str_map("envs")).transpose()?;
+            let configs = load_configs(&call).await?;
+            let mut config = match &target {
+                ExecutionTarget::ByName(name) => configs
+                    .iter()
+                    .find(|c| c.name == *name)
+                    .cloned()
+                    .ok_or_else(|| IdeError::not_found(format!("Run configuration with name '{name}' not found.")))?,
+                ExecutionTarget::ByContext(file, line) => {
+                    config_from_code_location(&call, configs.clone(), file, *line).await?
+                }
+            };
+            let stored_env = config.env.clone();
+            let overrides: Vec<(String, String)> = envs.clone().unwrap_or_default();
+            apply_overrides(
+                &mut config,
+                call.root(),
+                call.opt_str("programArguments")?,
+                call.opt_str("workingDirectory")?,
+                envs,
+            )?;
+            if !config.extras.compound.is_empty() {
+                return Err(IdeError::invalid(format!(
+                    "`{}` is a compound configuration, which cannot run through MCP; run its configurations ({}) \
+one by one",
+                    config.name,
+                    config.extras.compound.join(", ")
+                )));
+            }
+            let cwd = match config.cwd.as_deref() {
+                Some(p) => call.root().join(p),
+                None => call.root().to_path_buf(),
+            };
+            let detail = confirmation_detail(&config, &call.display(&cwd), &stored_env, &overrides, &configs);
+            call.confirm(&config.name, Some(detail)).await?;
+
+            let mut errors = BuildErrors::default();
+            if let Some(reason) = before_launch(&call, &config, &configs, &mut Vec::new(), &mut errors).await? {
+                return Err(execution_failed(&[errors.text(), Some(reason)]));
+            }
+            let collector = Arc::new(Mutex::new(OutputCollector::create(&config.name)?));
+            let output_path = collector.lock().path.clone();
+            let sink = collector.clone();
+            let emit = process_output(move |text| sink.lock().append(text));
+            let info = match crate::ops::run::start(&call.host(), call.window(), config, emit).await {
+                Ok(info) => info,
+                Err(e) => {
+                    let _ = std::fs::remove_file(&output_path);
+                    return Err(execution_failed(&[errors.text(), Some(e.message)]));
+                }
+            };
+
+            let exit = match limit {
+                Some(limit) if !limit.is_zero() => wait_exit(&call, info.id, Some(Instant::now() + limit)).await?,
+                _ => None,
+            };
+            let c = collector.lock();
+            let mut result = Map::new();
+            if let Some(Some(code)) = exit {
+                result.insert("exitCode".into(), code.into());
+            }
+            result.insert("output".into(), c.preview().into());
+            // An exited run whose whole output is in `output` needs no file.
+            if exit.is_none() || c.truncated {
+                result.insert("fullOutputPath".into(), c.path.to_string_lossy().into_owned().into());
+            } else {
+                let _ = std::fs::remove_file(&c.path);
+            }
+            Output::json(Value::Object(result))
+        },
+    )
+    .write()
+    .param(Param::optional("configurationName", ParamType::String, "Name of the existing run configuration to execute"))
+    .param(Param::optional(
+        "filePath",
+        ParamType::String,
+        "File path relative to the project root. Provide together with `line` to create and execute a temporary run \
+configuration from code context.",
+    ))
+    .param(Param::optional(
+        "line",
+        ParamType::Integer,
+        "1-based line number for `filePath`. Provide together with `filePath` and do not combine with \
+`configurationName`.",
+    ))
+    .param(Param::optional("timeout", ParamType::Integer, "Timeout in milliseconds"))
+    .param(Param::optional(
+        "waitForExit",
+        ParamType::Boolean,
+        "Whether to wait for process termination. If false, the tool returns immediately after the process starts and \
+ignores `timeout`.",
+    ))
+    .param(Param::optional(
+        "programArguments",
+        ParamType::String,
+        "Optional program arguments override for this launch only. Missing/null or empty string keeps the existing \
+value; whitespace-only string clears it.",
+    ))
+    .param(Param::optional(
+        "workingDirectory",
+        ParamType::String,
+        "Optional working directory override for this launch only. Missing/null or empty string keeps the existing \
+value; whitespace-only string clears it.",
+    ))
+    .param(Param::optional(
+        "envs",
+        ParamType::StringMap,
+        "Optional environment variable overrides for this launch only. Missing/null keeps existing env unchanged; when \
+provided, values are merged over existing env.",
+    ))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn config() -> RunConfig {
+        RunConfig {
+            id: "user:x".into(),
+            name: "x".into(),
+            kind: "shell".into(),
+            command: "prog".into(),
+            args: vec!["a".into()],
+            cwd: Some(std::path::PathBuf::from("sub").into()),
+            env: [("A".to_owned(), "1".to_owned())].into(),
+            detected: false,
+            is_test: false,
+            debug_adapter: None,
+            allow_parallel: false,
+            extras: Default::default(),
+        }
+    }
+
+    #[test]
+    fn empty_overrides_keep_and_blank_ones_clear() {
+        let root = Path::new("/");
+        let mut c = config();
+        apply_overrides(&mut c, root, Some(String::new()), Some(String::new()), None).unwrap();
+        assert_eq!(c, config());
+        apply_overrides(&mut c, root, Some(" ".into()), Some(" ".into()), Some(vec![("C".into(), "3".into())]))
+            .unwrap();
+        assert!(c.args.is_empty());
+        assert!(c.cwd.is_none());
+        assert_eq!(c.env.keys().collect::<Vec<_>>(), ["A", "C"]);
+        apply_overrides(&mut c, root, Some("x 'y z'".into()), None, None).unwrap();
+        assert_eq!(c.args, ["x", "y z"]);
+    }
+
+    #[test]
+    fn execution_targets_are_exclusive() {
+        let err = |n: Option<&str>, f: Option<&str>, l| {
+            execution_target(n.map(Into::into), f.map(Into::into), l).err().map(|e| e.message)
+        };
+        assert_eq!(
+            err(Some("a"), Some("f"), Some(1)).as_deref(),
+            Some("Pass either configurationName or filePath + line, but not both.")
+        );
+        assert_eq!(
+            err(None, Some("f"), None).as_deref(),
+            Some("Pass both filePath and line together, or use configurationName.")
+        );
+        assert_eq!(err(None, None, None).as_deref(), Some("Pass either configurationName or filePath + line."));
+        assert!(err(Some("a"), None, None).is_none());
+    }
+}

crates/ide-host/src/mcp/run/mod.rs

@@ -0,0 +1,25 @@
+//! Run configurations and builds; every call asks the user first.
+
+mod build;
+mod configs;
+mod output;
+mod process;
+mod targets;
+
+use crate::mcp::tool::{Call, Tool};
+use ide_core::IdeResult;
+use std::time::Duration;
+
+pub fn tools() -> Vec<Tool> {
+    vec![configs::get_run_configurations(), configs::execute_run_configuration(), build::build_project()]
+}
+
+/// The `timeout` argument: `default` when absent, at most `max` milliseconds. As in JetBrains
+/// (`withTimeoutOrNull`), zero or a negative value times out at once.
+fn timeout(call: &Call, default: usize, max: usize) -> IdeResult<Duration> {
+    Ok(match call.opt_i64("timeout")? {
+        None => Duration::from_millis(default as u64),
+        Some(n) if n <= 0 => Duration::ZERO,
+        Some(n) => Duration::from_millis((n as u64).min(max as u64)),
+    })
+}

crates/ide-host/src/mcp/run/output.rs

@@ -0,0 +1,188 @@
+// Ported from JetBrains intellij-community plugins/mcp-server (src/com/intellij/mcpserver/util/text.util.kt,
+// mcpserver.toolsets/src/util/OutputCollector.kt), Apache-2.0.
+//! Output of commands and runs: truncation, the run output collector and the private
+//! directory of full output files.
+
+use ide_core::IdeResult;
+use std::io::Write as _;
+use std::path::{Path, PathBuf};
+
+/// Marker of text cut by [`truncate_tail`].
+pub const TRUNCATED_MARKER: &str = "<<<...content truncated...>>>";
+/// Longest text [`truncate_tail`] returns (before its marker).
+pub const MAX_TEXT_LENGTH: usize = 64 * 1024;
+/// Characters of a run's output returned inline.
+pub const RUN_PREVIEW_MAX_LENGTH: usize = 10_000;
+pub const RUN_PREVIEW_TRUNCATED_MARKER: &str = "<truncated>";
+
+/// Console tail bounded by line count and character count.
+pub fn truncate_tail(text: &str, max_lines: usize, max_length: usize, marker: &str) -> String {
+    let lines: Vec<&str> = text.split('\n').collect();
+    let text = if lines.len() > max_lines {
+        [vec![marker], lines[lines.len() - (max_lines - 1)..].to_vec()].concat().join("\n")
+    } else {
+        text.to_owned()
+    };
+    if text.chars().count() <= max_length {
+        return text;
+    }
+    let start = text.char_indices().rev().nth(max_length - 1).map_or(0, |(i, _)| i);
+    format!("{marker}{}", &text[start..])
+}
+
+/// A run's output: all of it to a file, its first [`RUN_PREVIEW_MAX_LENGTH`] characters
+/// in memory (then [`RUN_PREVIEW_TRUNCATED_MARKER`]).
+pub struct OutputCollector {
+    pub path: PathBuf,
+    preview: String,
+    preview_chars: usize,
+    pub truncated: bool,
+    file: Option<std::fs::File>,
+}
+
+impl OutputCollector {
+    pub fn create(name: &str) -> IdeResult<Self> {
+        let (path, file) = temp_output_file(&format!("run-{name}"))?;
+        Ok(Self { path, preview: String::new(), preview_chars: 0, truncated: false, file: Some(file) })
+    }
+
+    pub fn append(&mut self, text: &str) {
+        // A failed write keeps the preview going; the file is then incomplete.
+        if let Some(f) = &mut self.file
+            && f.write_all(text.as_bytes()).is_err()
+        {
+            self.file = None;
+        }
+        if self.truncated {
+            return;
+        }
+        // As JetBrains: reaching the limit marks the preview truncated, even without more output.
+        let room = RUN_PREVIEW_MAX_LENGTH - self.preview_chars;
+        let chars = text.chars().count();
+        if chars < room {
+            self.preview_chars += chars;
+            self.preview.push_str(text);
+        } else {
+            let cut = text.char_indices().nth(room).map_or(text.len(), |(i, _)| i);
+            self.preview.push_str(&text[..cut]);
+            self.preview.push_str(RUN_PREVIEW_TRUNCATED_MARKER);
+            self.preview_chars = RUN_PREVIEW_MAX_LENGTH;
+            self.truncated = true;
+        }
+    }
+
+    pub fn preview(&self) -> &str {
+        &self.preview
+    }
+}
+
+/// Output files older than this are removed when a new one is created.
+const OUTPUT_MAX_AGE: std::time::Duration = std::time::Duration::from_secs(24 * 60 * 60);
+
+pub fn temp_output_file(prefix: &str) -> IdeResult<(PathBuf, std::fs::File)> {
+    let dir = output_dir()?;
+    remove_old_logs(&dir, OUTPUT_MAX_AGE);
+    let safe: String =
+        prefix.chars().map(|c| if c.is_ascii_alphanumeric() || c == '-' { c } else { '_' }).take(40).collect();
+    let path = dir.join(format!("{safe}-{}.log", uuid::Uuid::new_v4().simple()));
+    let mut options = std::fs::OpenOptions::new();
+    options.write(true).create_new(true);
+    #[cfg(unix)]
+    std::os::unix::fs::OpenOptionsExt::mode(&mut options, 0o600);
+    let file = options.open(&path)?;
+    Ok((path, file))
+}
+
+/// Best effort: removes `*.log` files in `dir` last modified more than `max_age` ago.
+fn remove_old_logs(dir: &Path, max_age: std::time::Duration) {
+    let Ok(entries) = std::fs::read_dir(dir) else { return };
+    let now = std::time::SystemTime::now();
+    for entry in entries.flatten() {
+        let path = entry.path();
+        if path.extension().is_none_or(|e| e != "log") {
+            continue;
+        }
+        let old = entry
+            .metadata()
+            .ok()
+            .filter(std::fs::Metadata::is_file)
+            .and_then(|m| m.modified().ok())
+            .and_then(|modified| now.duration_since(modified).ok())
+            .is_some_and(|age| age > max_age);
+        if old {
+            let _ = std::fs::remove_file(&path);
+        }
+    }
+}
+
+/// A directory only this user can read: output may hold secrets, and `/tmp` is shared on Linux.
+fn output_dir() -> IdeResult<PathBuf> {
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::{DirBuilderExt, MetadataExt};
+        let uid = rustix::process::getuid().as_raw();
+        let dir = std::env::temp_dir().join(format!("openidea-mcp-{uid}"));
+        match std::fs::DirBuilder::new().mode(0o700).create(&dir) {
+            Ok(()) => {}
+            Err(e) if e.kind() == std::io::ErrorKind::AlreadyExists => {}
+            Err(e) => return Err(e.into()),
+        }
+        let meta = std::fs::symlink_metadata(&dir)?;
+        if !meta.is_dir() || meta.uid() != uid || meta.mode() & 0o077 != 0 {
+            return Err(ide_core::IdeError::new(
+                ide_core::error::ErrorKind::PermissionDenied,
+                format!("{} is not a private directory of this user", dir.display()),
+            ));
+        }
+        Ok(dir)
+    }
+    #[cfg(not(unix))]
+    {
+        let dir = std::env::temp_dir().join("openidea-mcp");
+        std::fs::create_dir_all(&dir)?;
+        Ok(dir)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::time::Duration;
+
+    #[test]
+    fn preview_line_keeps_a_fixed_length() {
+        // JetBrains' `truncateRunConfigurationPreviewLine`: 1000 characters including the marker.
+        let line = "a".repeat(2000);
+        let cut = truncate_tail(&line, 3, 1000 - RUN_PREVIEW_TRUNCATED_MARKER.len(), RUN_PREVIEW_TRUNCATED_MARKER);
+        assert!(cut.starts_with("<truncated>"));
+        assert_eq!(cut.len(), 1000);
+    }
+
+    #[test]
+    fn collector_limits_the_preview_and_keeps_everything_in_the_file() {
+        let mut c = OutputCollector::create("test").unwrap();
+        let output = "a".repeat(RUN_PREVIEW_MAX_LENGTH + 1);
+        c.append(&output[..10]);
+        c.append(&output[10..]);
+        assert_eq!(c.preview(), format!("{}{RUN_PREVIEW_TRUNCATED_MARKER}", &output[..RUN_PREVIEW_MAX_LENGTH]));
+        assert!(c.truncated);
+        assert_eq!(std::fs::read_to_string(&c.path).unwrap(), output);
+        let _ = std::fs::remove_file(&c.path);
+    }
+
+    #[test]
+    fn removes_day_old_logs() {
+        let dir = tempfile::tempdir().unwrap();
+        let old = std::time::SystemTime::now() - Duration::from_secs(25 * 60 * 60);
+        for name in ["old.log", "new.log", "old.txt"] {
+            let file = std::fs::File::create(dir.path().join(name)).unwrap();
+            if name.starts_with("old") {
+                file.set_modified(old).unwrap();
+            }
+        }
+        remove_old_logs(dir.path(), OUTPUT_MAX_AGE);
+        assert!(!dir.path().join("old.log").exists());
+        assert!(dir.path().join("new.log").exists());
+        assert!(dir.path().join("old.txt").exists(), "only logs are removed");
+    }
+}

crates/ide-host/src/mcp/run/process.rs

@@ -0,0 +1,65 @@
+use ide_core::{IdeError, IdeResult};
+/// POSIX-like word splitting: whitespace separates, quotes group, `\` escapes (not inside `'…'`).
+pub fn split_words(line: &str) -> IdeResult<Vec<String>> {
+    let mut words = Vec::new();
+    let mut word = String::new();
+    let mut in_word = false;
+    let mut chars = line.chars();
+    while let Some(c) = chars.next() {
+        match c {
+            '\'' => {
+                in_word = true;
+                loop {
+                    match chars.next() {
+                        Some('\'') => break,
+                        Some(c) => word.push(c),
+                        None => return Err(IdeError::invalid("unterminated ' quote")),
+                    }
+                }
+            }
+            '"' => {
+                in_word = true;
+                loop {
+                    match chars.next() {
+                        Some('"') => break,
+                        Some('\\') => match chars.next() {
+                            Some(c @ ('"' | '\\' | '$' | '`')) => word.push(c),
+                            Some(c) => {
+                                word.push('\\');
+                                word.push(c);
+                            }
+                            None => return Err(IdeError::invalid("unterminated \" quote")),
+                        },
+                        Some(c) => word.push(c),
+                        None => return Err(IdeError::invalid("unterminated \" quote")),
+                    }
+                }
+            }
+            '\\' if !cfg!(windows) => {
+                in_word = true;
+                if let Some(c) = chars.next() {
+                    word.push(c);
+                }
+            }
+            c if c.is_whitespace() => {
+                if in_word {
+                    words.push(std::mem::take(&mut word));
+                    in_word = false;
+                }
+            }
+            c => {
+                in_word = true;
+                word.push(c);
+            }
+        }
+    }
+    if in_word {
+        words.push(word);
+    }
+    Ok(words)
+}
+
+pub fn quote(arg: &str) -> String {
+    let plain = !arg.is_empty() && arg.chars().all(|c| c.is_ascii_alphanumeric() || "-_./=:@%+,".contains(c));
+    if plain { arg.to_owned() } else { format!("'{}'", arg.replace('\'', "'\\''")) }
+}

crates/ide-host/src/mcp/run/targets.rs

@@ -0,0 +1,975 @@
+//! Run points inside a file (the editor's gutter ▶ icons) and the run configuration of
+//! one: a port of the frontend's `features/run/targets.ts` and `context.ts` for Rust,
+//! JavaScript/TypeScript, Python and Go. JVM files are not covered (the editor scans
+//! them with a parser of its own).
+
+use ide_run::RunConfig;
+use regex_lite::Regex;
+use std::path::Path;
+use std::sync::LazyLock;
+
+/// Above this size files are not scanned (generated / minified files).
+const MAX_SCAN: usize = 400_000;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum Kind {
+    Main,
+    Test,
+    Suite,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Target {
+    /// 0-based line of the declaration.
+    pub line: usize,
+    pub kind: Kind,
+    /// Display name (`adds_numbers`, `math > adds`).
+    pub name: String,
+    /// Rust module path, describe chain, Python class chain…
+    pub path: Vec<String>,
+}
+
+macro_rules! re {
+    ($name:ident, $re:expr) => {
+        static $name: LazyLock<Regex> = LazyLock::new(|| Regex::new($re).expect("valid regex"));
+    };
+}
+
+fn indent_of(s: &str) -> usize {
+    s.chars().take_while(|c| c.is_whitespace()).map(|c| if c == '\t' { 4 } else { 1 }).sum()
+}
+
+// ---------------------------------------------------------------- Rust
+
+re!(LINE_COMMENT, r"//.*$");
+re!(STRING, r#""(?:[^"\\]|\\.)*""#);
+re!(CHAR, r"'(?:[^'\\]|\\.)'");
+
+/// Strips string literals and line comments (rough) so braces inside them don't count.
+fn code_only(line: &str) -> String {
+    let line = LINE_COMMENT.replace(line, "");
+    let line = STRING.replace_all(&line, "\"\"");
+    CHAR.replace_all(&line, "''").into_owned()
+}
+
+re!(RUST_SRC, r"(?:^|/)src/(.+)\.rs$");
+
+fn rust_module_prefix(rel: &str) -> Vec<String> {
+    let Some(m) = RUST_SRC.captures(rel) else { return Vec::new() };
+    let mut parts: Vec<String> = m[1].split('/').map(str::to_owned).collect();
+    let last = parts.last().cloned().unwrap_or_default();
+    if parts.len() == 1 && (last == "lib" || last == "main") || parts[0] == "bin" {
+        return Vec::new();
+    }
+    if last == "mod" {
+        parts.pop();
+    }
+    parts
+}
+
+re!(RUST_TEST_ATTR, r"^#\[(?:[\w:]+::)?test\b|^#\[(?:tokio|async_std|actix_rt|rstest|test_case)(?:::\w+)?\b");
+re!(RUST_CFG_TEST, r"^#\[cfg\(test\)\]");
+re!(RUST_FN, r"^(?:pub(?:\([^)]*\))?\s+)?(?:async\s+)?(?:unsafe\s+)?fn\s+(\w+)");
+re!(RUST_MOD, r"^(?:pub(?:\([^)]*\))?\s+)?mod\s+(\w+)\s*\{");
+re!(RUST_MAIN_FILE, r"(?:^|/)(?:src/main|src/bin/[^/]+|examples/[^/]+)\.rs$");
+
+fn rust_targets(lines: &[&str], rel: &str) -> Vec<Target> {
+    let mut out: Vec<Target> = Vec::new();
+    let prefix = rust_module_prefix(rel);
+    let mut mods: Vec<(String, i64)> = Vec::new();
+    let mut depth: i64 = 0;
+    let mut pending_test = false;
+    let mut pending_cfg_test = false;
+    for (i, raw) in lines.iter().enumerate() {
+        let line = code_only(raw);
+        let trimmed = line.trim();
+        if RUST_TEST_ATTR.is_match(trimmed) {
+            pending_test = true;
+        }
+        if RUST_CFG_TEST.is_match(trimmed) {
+            pending_cfg_test = true;
+        }
+        let mod_path = || prefix.iter().cloned().chain(mods.iter().map(|m| m.0.clone())).collect::<Vec<_>>();
+        if let Some(f) = RUST_FN.captures(trimmed) {
+            let name = f[1].to_owned();
+            if pending_test {
+                let mut path = mod_path();
+                path.push(name.clone());
+                out.push(Target { line: i, kind: Kind::Test, name, path });
+            } else if name == "main" && depth == 0 && RUST_MAIN_FILE.is_match(rel) {
+                out.push(Target { line: i, kind: Kind::Main, name, path: Vec::new() });
+            }
+            pending_test = false;
+            pending_cfg_test = false;
+        } else if let Some(m) = RUST_MOD.captures(trimmed) {
+            let name = m[1].to_owned();
+            let mut path = mod_path();
+            path.push(name.clone());
+            if pending_cfg_test || name == "tests" {
+                out.push(Target { line: i, kind: Kind::Suite, name: name.clone(), path });
+            }
+            mods.push((name, depth));
+            pending_test = false;
+            pending_cfg_test = false;
+        } else if !trimmed.is_empty() && !trimmed.starts_with("#[") && !trimmed.starts_with("//") {
+            pending_test = false;
+            if !trimmed.starts_with('#') {
+                pending_cfg_test = false;
+            }
+        }
+        for ch in line.chars() {
+            if ch == '{' {
+                depth += 1;
+            } else if ch == '}' {
+                depth -= 1;
+                while mods.last().is_some_and(|m| m.1 >= depth) {
+                    mods.pop();
+                }
+            }
+        }
+    }
+    // A suite that contains no tests is noise.
+    let tests: Vec<Vec<String>> = out.iter().filter(|t| t.kind == Kind::Test).map(|t| t.path.clone()).collect();
+    out.retain(|t| t.kind != Kind::Suite || tests.iter().any(|p| p.len() > t.path.len() && p.starts_with(&t.path)));
+    out
+}
+
+// ---------------------------------------------------------------- JavaScript / TypeScript
+
+re!(
+    JS_CALL,
+    r"^(\s*)(describe|suite|context|test|it)\b(?:\.(?:only|skip|todo|concurrent|failing|sequential))*(\.each\s*(?:\(.*?\)|`[^`]*`))?\s*\(\s*"
+);
+
+/// The string literal at the start of `s` (quote, then text up to the same unescaped quote).
+fn js_string(s: &str) -> Option<(char, String)> {
+    let mut chars = s.chars();
+    let quote = chars.next().filter(|q| matches!(q, '\'' | '"' | '`'))?;
+    let mut raw = String::new();
+    while let Some(c) = chars.next() {
+        if c == quote {
+            return Some((quote, raw));
+        }
+        raw.push(c);
+        if c == '\\' {
+            raw.push(chars.next()?);
+        }
+    }
+    None
+}
+
+re!(JS_ESCAPE, r"\\(.)");
+
+fn js_targets(lines: &[&str]) -> Vec<Target> {
+    let mut out = Vec::new();
+    let mut stack: Vec<(usize, String)> = Vec::new();
+    for (i, line) in lines.iter().enumerate() {
+        let Some(m) = JS_CALL.captures(line) else { continue };
+        let Some((_quote, raw)) = js_string(&line[m.get(0).map_or(0, |g| g.end())..]) else { continue };
+        let indent = indent_of(&m[1]);
+        while stack.last().is_some_and(|s| s.0 >= indent) {
+            stack.pop();
+        }
+        let name = JS_ESCAPE.replace_all(&raw, "$1").into_owned();
+        let mut path: Vec<String> = stack.iter().map(|s| s.1.clone()).collect();
+        path.push(name.clone());
+        let suite = matches!(&m[2], "describe" | "suite" | "context");
+        out.push(Target { line: i, kind: if suite { Kind::Suite } else { Kind::Test }, name: path.join(" > "), path });
+        if suite {
+            stack.push((indent, name));
+        }
+    }
+    out
+}
+
+fn escape_regexp(s: &str) -> String {
+    let mut out = String::with_capacity(s.len());
+    for c in s.chars() {
+        if ".*+?^${}()|[]\\".contains(c) {
+            out.push('\\');
+        }
+        out.push(c);
+    }
+    out
+}
+
+re!(JS_PATTERN_PLACEHOLDER, r"%[sdifjo#p]|\\\$\\\{[^}]*\\\}|\$\w+");
+
+/// Jest / Vitest `-t` pattern for a test (full name = describe chain + name, space separated).
+fn js_name_pattern(target: &Target) -> String {
+    let pattern = escape_regexp(&target.path.join(" "));
+    // `test.each` placeholders (%s, $name, ${…}) match anything.
+    let pattern = JS_PATTERN_PLACEHOLDER.replace_all(&pattern, ".*");
+    if target.kind == Kind::Suite { format!("^{pattern}") } else { format!("^{pattern}$") }
+}
+
+// ---------------------------------------------------------------- Python
+
+re!(PY_COMMENT, r"^\s*#");
+re!(PY_CLASS, r"^\s*class\s+(\w+)");
+re!(PY_TEST_DEF, r"^\s*(?:async\s+)?def\s+(test\w*)\s*\(");
+re!(PY_MAIN, r#"^if\s+__name__\s*==\s*['"]__main__['"]\s*:"#);
+
+fn python_targets(lines: &[&str]) -> Vec<Target> {
+    let mut out = Vec::new();
+    let mut classes: Vec<(usize, String, bool)> = Vec::new();
+    for (i, line) in lines.iter().enumerate() {
+        if line.trim().is_empty() || PY_COMMENT.is_match(line) {
+            continue;
+        }
+        let indent = indent_of(line);
+        while classes.last().is_some_and(|c| c.0 >= indent) {
+            classes.pop();
+        }
+        if let Some(c) = PY_CLASS.captures(line) {
+            let test = c[1].starts_with("Test") && classes.iter().all(|c| c.2);
+            classes.push((indent, c[1].to_owned(), test));
+            if test {
+                let path: Vec<String> = classes.iter().map(|c| c.1.clone()).collect();
+                out.push(Target { line: i, kind: Kind::Suite, name: c[1].to_owned(), path });
+            }
+            continue;
+        }
+        if let Some(d) = PY_TEST_DEF.captures(line)
+            && classes.iter().all(|c| c.2)
+        {
+            let mut path: Vec<String> = classes.iter().map(|c| c.1.clone()).collect();
+            path.push(d[1].to_owned());
+            out.push(Target { line: i, kind: Kind::Test, name: path.join("."), path });
+            continue;
+        }
+        if indent == 0 && PY_MAIN.is_match(line) {
+            out.push(Target { line: i, kind: Kind::Main, name: "main".into(), path: Vec::new() });
+        }
+    }
+    out
+}
+
+// ---------------------------------------------------------------- Go
+
+re!(GO_PACKAGE_MAIN, r"^package\s+main\b");
+re!(GO_TEST, r"^func\s+(Test\w*|Benchmark\w*|Example\w*|Fuzz\w*)\s*\(\s*(?:\w+\s+\*testing\.[TFB])?\s*\)?");
+re!(GO_TESTING_ARG, r"\*testing\.[TFB]");
+re!(GO_TESTING_TB, r"\*testing\.[TB]\b");
+re!(GO_MAIN, r"^func\s+main\s*\(\s*\)");
+re!(GO_ONE_LINE, r"\}\s*(?://.*)?$");
+re!(GO_RUN_LITERAL, r#"\b\w+\.Run\(\s*"((?:[^"\\]|\\.)*)"\s*,"#);
+re!(GO_RUN_FIELD, r"\b\w+\.Run\(\s*\w+\.(\w+)\s*,");
+re!(GO_RUN_KEY, r"\b\w+\.Run\(\s*(\w+)\s*,");
+re!(GO_MAP_KEY, r#"^\s*"((?:[^"\\]|\\.)*)"\s*:\s*\{"#);
+re!(WHITESPACE, r"\s");
+
+fn go_targets(lines: &[&str]) -> Vec<Target> {
+    let mut out = Vec::new();
+    let is_main = lines.iter().any(|l| GO_PACKAGE_MAIN.is_match(l));
+    for (i, line) in lines.iter().enumerate() {
+        if let Some(t) = GO_TEST.captures(line) {
+            let name = t[1].to_owned();
+            if name.starts_with("Example") || GO_TESTING_ARG.is_match(line) {
+                out.push(Target { line: i, kind: Kind::Test, name: name.clone(), path: vec![name.clone()] });
+                if GO_TESTING_TB.is_match(line) {
+                    out.extend(go_subtests(lines, i, &name));
+                }
+                continue;
+            }
+        }
+        if is_main && GO_MAIN.is_match(line) {
+            out.push(Target { line: i, kind: Kind::Main, name: "main".into(), path: Vec::new() });
+        }
+    }
+    out
+}
+
+/// Subtests of the test function at `start`: `t.Run("name", …)`, and table entries run with
+/// `t.Run(tt.name, …)` (`{name: "…", …}`) or keyed by name (`"…": {…}`).
+fn go_subtests(lines: &[&str], start: usize, test: &str) -> Vec<Target> {
+    if GO_ONE_LINE.is_match(lines[start]) {
+        return Vec::new();
+    }
+    let mut end = start;
+    while end + 1 < lines.len() && !lines[end].starts_with('}') {
+        end += 1;
+    }
+    let body = &lines[start + 1..end.max(start + 1)];
+    let mut out: Vec<Target> = Vec::new();
+    let mut add = |offset: usize, name: &str| {
+        let sub = WHITESPACE.replace_all(&JS_ESCAPE.replace_all(name, "$1"), "_").into_owned();
+        if !out.iter().any(|t| t.path[1] == sub) {
+            out.push(Target {
+                line: start + 1 + offset,
+                kind: Kind::Test,
+                name: format!("{test}/{sub}"),
+                path: vec![test.to_owned(), sub],
+            });
+        }
+    };
+    let mut fields: Vec<String> = Vec::new();
+    let mut keys: Vec<String> = Vec::new();
+    for (i, l) in body.iter().enumerate() {
+        if let Some(m) = GO_RUN_LITERAL.captures(l) {
+            add(i, &m[1]);
+        }
+        if let Some(m) = GO_RUN_FIELD.captures(l) {
+            fields.push(m[1].to_owned());
+        }
+        if let Some(m) = GO_RUN_KEY.captures(l) {
+            let range = Regex::new(&format!(r"\bfor\s+{}\s*,\s*\w+\s*:=\s*range\b", &m[1])).expect("valid regex");
+            if body[..i].iter().any(|b| range.is_match(b)) {
+                keys.push(m[1].to_owned());
+            }
+        }
+    }
+    if !fields.is_empty() || !keys.is_empty() {
+        let field_res: Vec<Regex> = fields
+            .iter()
+            .map(|f| Regex::new(&format!(r#"\b{f}\s*:\s*"((?:[^"\\]|\\.)*)""#)).expect("valid regex"))
+            .collect();
+        for (i, l) in body.iter().enumerate() {
+            for re in &field_res {
+                if let Some(m) = re.captures(l) {
+                    add(i, &m[1]);
+                }
+            }
+            if !keys.is_empty()
+                && let Some(m) = GO_MAP_KEY.captures(l)
+            {
+                add(i, &m[1]);
+            }
+        }
+    }
+    out.sort_by_key(|t| t.line);
+    out
+}
+
+// ---------------------------------------------------------------- detection
+
+re!(JS_FILE, r"\.[cm]?[jt]sx?$");
+re!(JS_TEST_FILE, r"\.(test|spec)\.[cm]?[jt]sx?$|(^|/)__tests__/");
+re!(PY_TEST_FILE, r"(^|/)(test_[^/]*|[^/]*_test)\.py$|(^|/)tests?/");
+
+/// Run targets of a file (`rel`: project-relative with `/`, picks the language).
+pub fn detect(text: &str, rel: &str) -> Vec<Target> {
+    if text.len() > MAX_SCAN {
+        return Vec::new();
+    }
+    let lines: Vec<&str> = text.split('\n').map(|l| l.strip_suffix('\r').unwrap_or(l)).collect();
+    if rel.ends_with(".rs") {
+        rust_targets(&lines, rel)
+    } else if JS_FILE.is_match(rel) {
+        if JS_TEST_FILE.is_match(rel) { js_targets(&lines) } else { Vec::new() }
+    } else if rel.ends_with(".py") {
+        let test_file = PY_TEST_FILE.is_match(rel);
+        python_targets(&lines).into_iter().filter(|t| t.kind == Kind::Main || test_file).collect()
+    } else if rel.ends_with(".go") {
+        let test_file = rel.ends_with("_test.go");
+        go_targets(&lines).into_iter().filter(|t| t.kind == Kind::Main || test_file).collect()
+    } else {
+        Vec::new()
+    }
+}
+
+/// The last line (0-based) of the block declared at `start`: by indentation in Python, else
+/// where the braces opened on (or, for a Rust signature, after) the declaration close again.
+fn block_end(lines: &[&str], start: usize, rel: &str) -> usize {
+    if rel.ends_with(".py") {
+        let indent = indent_of(lines[start]);
+        let mut end = start;
+        for (i, line) in lines.iter().enumerate().skip(start + 1) {
+            if line.trim().is_empty() || PY_COMMENT.is_match(line) {
+                continue;
+            }
+            if indent_of(line) <= indent {
+                break;
+            }
+            end = i;
+        }
+        return end;
+    }
+    let rust = rel.ends_with(".rs");
+    let mut depth: i64 = 0;
+    let mut opened = false;
+    for (i, raw) in lines.iter().enumerate().skip(start) {
+        let line = code_only(raw);
+        for ch in line.chars() {
+            match ch {
+                '{' => {
+                    depth += 1;
+                    opened = true;
+                }
+                '}' => depth -= 1,
+                // A Rust declaration without a body (`fn f();`).
+                ';' if rust && !opened => return i,
+                _ => {}
+            }
+            if opened && depth <= 0 {
+                return i;
+            }
+        }
+        // Only a Rust signature continues on the next lines; a call without a block ends here.
+        if !opened && !rust {
+            return i;
+        }
+    }
+    lines.len().saturating_sub(1)
+}
+
+/// The run targets whose declaration or body contains `line` (0-based), innermost first.
+pub fn enclosing(text: &str, rel: &str, line: usize) -> Vec<Target> {
+    let lines: Vec<&str> = text.split('\n').map(|l| l.strip_suffix('\r').unwrap_or(l)).collect();
+    let mut out: Vec<Target> =
+        detect(text, rel).into_iter().filter(|t| t.line <= line && line <= block_end(&lines, t.line, rel)).collect();
+    out.sort_by_key(|t| std::cmp::Reverse(t.line));
+    out
+}
+
+// ---------------------------------------------------------------- configurations
+
+/// A configuration's working directory relative to the project root, with `/` (Go: its module).
+fn cwd_of(root: &Path, c: &RunConfig) -> String {
+    let module = (c.kind == "go").then(|| c.extras.params.get("module").cloned()).flatten();
+    let cwd = module
+        .or_else(|| c.cwd.as_deref().map(|p| p.strip_prefix(root).unwrap_or(p).to_string_lossy().replace('\\', "/")));
+    let cwd = cwd.unwrap_or_default();
+    let cwd = cwd.strip_prefix("./").or_else(|| cwd.strip_prefix('.')).unwrap_or(&cwd);
+    cwd.trim_end_matches('/').to_owned()
+}
+
+/// Configs whose working directory most specifically contains `rel` (ties in their original order).
+fn all_closest<'a>(root: &Path, configs: &[&'a RunConfig], rel: &str) -> Vec<&'a RunConfig> {
+    let score = |c: &RunConfig| -> Option<usize> {
+        let cwd = cwd_of(root, c);
+        if cwd.is_empty() { Some(0) } else { (rel == cwd || rel.starts_with(&format!("{cwd}/"))).then_some(cwd.len()) }
+    };
+    let scored: Vec<(&RunConfig, usize)> = configs.iter().filter_map(|c| score(c).map(|s| (*c, s))).collect();
+    let best = scored.iter().map(|s| s.1).max();
+    scored.into_iter().filter(|s| Some(s.1) == best).map(|s| s.0).collect()
+}
+
+fn closest<'a>(root: &Path, configs: &[&'a RunConfig], rel: &str) -> Option<&'a RunConfig> {
+    all_closest(root, configs, rel).into_iter().next()
+}
+
+fn rel_to_cwd(root: &Path, rel: &str, c: &RunConfig) -> String {
+    let cwd = cwd_of(root, c);
+    match rel.strip_prefix(&format!("{cwd}/")) {
+        Some(inner) if !cwd.is_empty() => inner.to_owned(),
+        _ => rel.to_owned(),
+    }
+}
+
+fn file_name(rel: &str) -> &str {
+    rel.rsplit('/').next().unwrap_or(rel)
+}
+
+fn dir_of(p: &str) -> &str {
+    p.rfind('/').map_or("", |i| &p[..i])
+}
+
+fn derived(base: &RunConfig, rel: &str, args: Vec<String>) -> RunConfig {
+    RunConfig {
+        id: format!("context:{}:{rel}", base.id),
+        name: file_name(rel).to_owned(),
+        args,
+        detected: true,
+        ..base.clone()
+    }
+}
+
+/// Kinds whose test configs can run a file of this extension.
+fn test_kinds(rel: &str) -> &'static [&'static str] {
+    if JS_FILE.is_match(rel) {
+        &["npm", "deno", "bun"]
+    } else if rel.ends_with(".py") {
+        &["pytest", "python"]
+    } else if rel.ends_with(".go") {
+        &["go"]
+    } else if rel.ends_with(".rs") {
+        &["cargo"]
+    } else {
+        &[]
+    }
+}
+
+/// The project's Python interpreter as `(command, leading args)`, from detected configs.
+fn project_python(configs: &[RunConfig]) -> Option<(String, Vec<String>)> {
+    if let Some(py) = configs.iter().find(|c| c.kind == "python") {
+        let prefix = match py.args.iter().position(|a| a == "-m") {
+            Some(m) => py.args[..m].to_vec(),
+            None => py.args.iter().filter(|a| !a.ends_with(".py")).cloned().collect(),
+        };
+        return Some((py.command.clone(), prefix));
+    }
+    let pytest = configs.iter().find(|c| c.kind == "pytest")?;
+    static VENV: LazyLock<Regex> =
+        LazyLock::new(|| Regex::new(r"^(.*[/\\](?:bin|Scripts)[/\\])pytest(\.exe)?$").expect("valid regex"));
+    if let Some(m) = VENV.captures(&pytest.command) {
+        return Some((format!("{}python{}", &m[1], m.get(2).map_or("", |g| g.as_str())), Vec::new()));
+    }
+    if let Some(m) = pytest.args.iter().position(|a| a == "-m")
+        && pytest.args.get(m + 1).is_some_and(|a| a == "pytest")
+    {
+        return Some((pytest.command.clone(), pytest.args[..m].to_vec()));
+    }
+    if pytest.args.first().is_some_and(|a| a == "run") && pytest.args.get(1).is_some_and(|a| a == "pytest") {
+        return Some((pytest.command.clone(), vec!["run".into(), "python".into()]));
+    }
+    None
+}
+
+fn blank(id: String, name: &str, kind: &str, command: String, args: Vec<String>) -> RunConfig {
+    RunConfig {
+        id,
+        name: name.to_owned(),
+        kind: kind.to_owned(),
+        command,
+        args,
+        cwd: None,
+        env: Default::default(),
+        detected: true,
+        is_test: false,
+        debug_adapter: None,
+        allow_parallel: false,
+        extras: Default::default(),
+    }
+}
+
+/// PyCharm runs pytest for a test file even when the project declares no test setup.
+fn implicit_pytest(rel: &str, configs: &[RunConfig]) -> Option<RunConfig> {
+    if !rel.ends_with(".py") {
+        return None;
+    }
+    let (command, mut args) = project_python(configs).unwrap_or_else(|| ("python3".into(), Vec::new()));
+    args.extend(["-m".to_owned(), "pytest".to_owned()]);
+    let mut c = blank("pytest:implicit".into(), "pytest", "pytest", command, args);
+    c.is_test = true;
+    c.debug_adapter = Some("debugpy".into());
+    Some(c)
+}
+
+fn test_base_for(root: &Path, rel: &str, configs: &[RunConfig]) -> Option<RunConfig> {
+    let kinds = test_kinds(rel);
+    // Configurations produced from a test or file are results of narrowing, never bases for it.
+    let candidates: Vec<&RunConfig> = configs
+        .iter()
+        .filter(|c| c.is_test && kinds.contains(&c.kind.as_str()) && !c.id.starts_with("context:"))
+        .collect();
+    closest(root, &candidates, rel).or(candidates.first().copied()).cloned().or_else(|| implicit_pytest(rel, configs))
+}
+
+/// Go test flags may come before or after package targets; binary arguments start at `-args`.
+fn go_test_parts(args: &[String]) -> (Vec<String>, Vec<String>, Vec<String>) {
+    const BOOLEAN_FLAGS: &[&str] = &[
+        "-a",
+        "-n",
+        "-race",
+        "-msan",
+        "-asan",
+        "-cover",
+        "-linkshared",
+        "-modcacherw",
+        "-trimpath",
+        "-v",
+        "-work",
+        "-x",
+        "-json",
+        "-c",
+        "-i",
+        "-short",
+        "-failfast",
+        "-benchmem",
+        "-fullpath",
+        "-buildvcs",
+    ];
+    let (mut flags, mut targets, mut program) = (Vec::new(), Vec::new(), Vec::new());
+    let mut i = 1;
+    while i < args.len() {
+        let arg = &args[i];
+        if arg == "-args" || arg == "--" {
+            program = args[i..].to_vec();
+            break;
+        }
+        if arg.starts_with('-') {
+            flags.push(arg.clone());
+            if !arg.contains('=') && !BOOLEAN_FLAGS.contains(&arg.as_str()) && i + 1 < args.len() {
+                i += 1;
+                flags.push(args[i].clone());
+            }
+        } else {
+            targets.push(arg.clone());
+        }
+        i += 1;
+    }
+    (flags, targets, program)
+}
+
+fn without_go_selection(flags: &[String]) -> Vec<String> {
+    let mut out = Vec::new();
+    let mut i = 0;
+    while i < flags.len() {
+        let f = flags[i].as_str();
+        if matches!(f, "-run" | "-skip" | "-bench" | "-fuzz") {
+            i += 2;
+            continue;
+        }
+        if ["-run=", "-skip=", "-bench=", "-fuzz="].iter().any(|p| f.starts_with(p)) {
+            i += 1;
+            continue;
+        }
+        out.push(flags[i].clone());
+        i += 1;
+    }
+    out
+}
+
+/// File-level test configuration for `rel` (the closest matching test config narrowed to the file).
+fn test_config_for(root: &Path, rel: &str, configs: &[RunConfig]) -> Option<RunConfig> {
+    let base = test_base_for(root, rel, configs)?;
+    let file = rel_to_cwd(root, rel, &base);
+    let with = |extra: &[String]| [base.args.clone(), extra.to_vec()].concat();
+    Some(match base.kind.as_str() {
+        // `npm run test -- file` works for npm, pnpm, yarn and bun.
+        "npm" | "bun" if base.args.iter().any(|a| a == "--") => derived(&base, rel, with(&[file])),
+        "npm" | "bun" => derived(&base, rel, with(&["--".into(), file])),
+        "deno" | "pytest" | "python" => derived(&base, rel, with(&[file])),
+        "go" => {
+            let dir = dir_of(&file);
+            let target = if dir.is_empty() { ".".to_owned() } else { format!("./{dir}") };
+            let (flags, _, program) = go_test_parts(&base.args);
+            let args = [vec!["test".to_owned()], flags, vec![target.clone()], program].concat();
+            let mut c = derived(&base, rel, args);
+            c.name = format!("go test {target}");
+            if c.extras.params.contains_key("goKind") {
+                c.extras.params.insert("scope".into(), "directory".into());
+                c.extras.params.insert("target".into(), target);
+            }
+            c
+        }
+        "cargo" => {
+            static TESTS: LazyLock<Regex> =
+                LazyLock::new(|| Regex::new(r"(?:^|/)tests/([^/]+)\.rs$").expect("valid regex"));
+            match TESTS.captures(rel) {
+                Some(m) => {
+                    // Cargo's own options go before the test binary's `--`.
+                    let at = base.args.iter().position(|a| a == "--").unwrap_or(base.args.len());
+                    let mut args = base.args.clone();
+                    args.splice(at..at, ["--test".to_owned(), m[1].to_owned()]);
+                    derived(&base, rel, args)
+                }
+                None => base,
+            }
+        }
+        _ => base,
+    })
+}
+
+fn main_config_for(root: &Path, rel: &str, configs: &[RunConfig]) -> Option<RunConfig> {
+    if rel.ends_with(".rs") {
+        static BIN: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"src/bin/([^/]+)\.rs$").expect("valid regex"));
+        let bin = BIN.captures(rel).map(|m| m[1].to_owned());
+        let runs: Vec<&RunConfig> =
+            configs.iter().filter(|c| c.kind == "cargo" && c.id.starts_with("cargo:run")).collect();
+        let by_bin =
+            bin.and_then(|b| runs.iter().find(|c| c.id == format!("cargo:run:{b}") || c.args.contains(&b)).copied());
+        return by_bin.or_else(|| closest(root, &runs, rel)).or(runs.first().copied()).cloned();
+    }
+    if rel.ends_with(".go") {
+        let gos: Vec<&RunConfig> = configs.iter().filter(|c| c.kind == "go").collect();
+        let runs: Vec<&RunConfig> =
+            gos.iter().filter(|c| c.args.first().is_some_and(|a| a == "run")).copied().collect();
+        // The module containing the file (nested modules run from their own directory).
+        let base = closest(root, &runs, rel)
+            .or_else(|| closest(root, &gos, rel))
+            .or(runs.first().copied())
+            .or(gos.first().copied())?;
+        let dir = rel_to_cwd(root, rel, base);
+        let dir = dir_of(&dir);
+        let target = if dir.is_empty() { ".".to_owned() } else { format!("./{dir}") };
+        if let Some(hit) = runs.iter().find(|c| c.cwd == base.cwd && c.args.get(1) == Some(&target)) {
+            return Some((*hit).clone());
+        }
+        let mut c = derived(base, rel, vec!["run".into(), target.clone()]);
+        c.name = format!("go run {target}");
+        c.is_test = false;
+        return Some(c);
+    }
+    None
+}
+
+fn script_config_for(rel: &str, configs: &[RunConfig]) -> Option<RunConfig> {
+    let id = format!("context:file:{rel}");
+    let name = file_name(rel);
+    let script = |command: &str, args: Vec<String>| blank(id.clone(), name, "shell", command.to_owned(), args);
+    if rel.ends_with(".py") {
+        // Reuse the project's interpreter (venv / uv / poetry) when detected.
+        let (command, mut args) = project_python(configs).unwrap_or_else(|| ("python3".into(), Vec::new()));
+        args.push(rel.to_owned());
+        let mut c = blank(id, name, "python", command, args);
+        c.debug_adapter = Some("debugpy".into());
+        return Some(c);
+    }
+    static JS: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"\.[cm]?js$").expect("valid regex"));
+    if JS.is_match(rel) {
+        return Some(script("node", vec![rel.to_owned()]));
+    }
+    if rel.ends_with(".ts") {
+        return Some(script("npx", vec!["tsx".into(), rel.to_owned()]));
+    }
+    for (ext, shell) in [(".zsh", "zsh"), (".bash", "bash"), (".sh", "sh")] {
+        if rel.ends_with(ext) {
+            return Some(script(shell, vec![rel.to_owned()]));
+        }
+    }
+    None
+}
+
+re!(TEST_FILE, r"\.(test|spec)\.[cm]?[jt]sx?$|(^|/)__tests__/|(^|/)(test_[^/]*\.py|[^/]*_test\.py|[^/]*_test\.go)$");
+re!(RUST_TESTS_FILE, r"(^|/)tests/[^/]+\.rs$");
+re!(RUST_MAIN_ROLE, r"(^|/)src/main\.rs$|(^|/)src/bin/[^/]+\.rs$");
+re!(GO_PACKAGE_MAIN_MULTILINE, r"(?m)^\s*package\s+main\b");
+re!(SCRIPT_FILE, r"\.(py|sh|bash|zsh|[cm]?js|ts)$");
+
+/// "Run Context Configuration" for the whole file: its tests, its main target or the script.
+pub fn context_config(root: &Path, rel: &str, configs: &[RunConfig], content: &str) -> Option<RunConfig> {
+    let name = file_name(rel);
+    if TEST_FILE.is_match(rel) || (RUST_TESTS_FILE.is_match(rel) && name != "mod.rs") {
+        return test_config_for(root, rel, configs);
+    }
+    if RUST_MAIN_ROLE.is_match(rel) || (rel.ends_with(".go") && GO_PACKAGE_MAIN_MULTILINE.is_match(content)) {
+        return main_config_for(root, rel, configs).or_else(|| script_config_for(rel, configs));
+    }
+    if SCRIPT_FILE.is_match(name) {
+        return script_config_for(rel, configs);
+    }
+    None
+}
+
+fn replace_last(mut args: Vec<String>, f: impl FnOnce(&str) -> String) -> Vec<String> {
+    if let Some(last) = args.last_mut() {
+        *last = f(last);
+    }
+    args
+}
+
+/// The run configuration of one target, or `None` when the project has no matching runner.
+pub fn target_config(
+    root: &Path,
+    target: &Target,
+    rel: &str,
+    configs: &[RunConfig],
+    content: &str,
+) -> Option<RunConfig> {
+    if target.kind == Kind::Main {
+        return context_config(root, rel, configs, content);
+    }
+    let file = test_config_for(root, rel, configs)?;
+    let short =
+        if target.kind == Kind::Suite { target.path.last().cloned().unwrap_or_default() } else { target.name.clone() };
+    let named = |args: Vec<String>| RunConfig {
+        id: format!("context:target:{}:{rel}:{}", file.id, target.path.join("/")),
+        name: short.clone(),
+        args,
+        detected: true,
+        ..file.clone()
+    };
+    let with = |extra: Vec<String>| [file.args.clone(), extra].concat();
+    match file.kind.as_str() {
+        "npm" | "bun" | "deno" => Some(named(with(vec!["-t".into(), js_name_pattern(target)]))),
+        "pytest" | "python" => {
+            Some(named(replace_last(file.args.clone(), |f| format!("{f}::{}", target.path.join("::")))))
+        }
+        "go" => {
+            let pattern = format!("^{}$", target.path.iter().map(|p| escape_regexp(p)).collect::<Vec<_>>().join("$/^"));
+            let benchmark = target.path.first().is_some_and(|p| p.starts_with("Benchmark"));
+            let (flags, targets, program) = go_test_parts(&file.args);
+            let selection: Vec<String> = if benchmark {
+                vec!["-run".into(), "^$".into(), "-bench".into(), pattern.clone()]
+            } else {
+                vec!["-run".into(), pattern.clone()]
+            };
+            let flags = without_go_selection(&flags);
+            let mut c = named([vec!["test".to_owned()], flags.clone(), targets, selection, program].concat());
+            if c.extras.params.contains_key("goKind") {
+                let mut tool_args: Vec<String> = flags;
+                if benchmark {
+                    tool_args.extend(["-bench".to_owned(), pattern.clone()]);
+                }
+                c.extras.params.insert("pattern".into(), if benchmark { "^$".into() } else { pattern });
+                c.extras.params.insert(
+                    "toolArgs".into(),
+                    tool_args.iter().map(|a| super::process::quote(a)).collect::<Vec<_>>().join(" "),
+                );
+            }
+            Some(c)
+        }
+        "cargo" => {
+            let path = target.path.join("::");
+            // Test-binary arguments follow the one `--` (`cargo test -- --nocapture` has it already).
+            let separator: Vec<String> =
+                if file.args.iter().any(|a| a == "--") { Vec::new() } else { vec!["--".into()] };
+            Some(named(if target.kind == Kind::Suite {
+                with([separator, vec![format!("{path}::")]].concat())
+            } else {
+                with([separator, vec![path, "--exact".into()]].concat())
+            }))
+        }
+        _ => None,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn pick(ts: &[Target]) -> Vec<(usize, Kind, String)> {
+        ts.iter().map(|t| (t.line, t.kind, t.path.join("/"))).collect()
+    }
+
+    #[test]
+    fn rust_main_tests_and_test_modules() {
+        let src = [
+            "fn main() {}",
+            "#[cfg(test)]",
+            "mod tests {",
+            "    use super::*;",
+            "    #[test]",
+            "    fn adds() { let s = \"}\"; }",
+            "    #[tokio::test]",
+            "    #[ignore]",
+            "    async fn async_one() {}",
+            "    fn helper() {}",
+            "}",
+            "fn after() {}",
+        ]
+        .join("\n");
+        assert_eq!(
+            pick(&detect(&src, "src/main.rs")),
+            [
+                (0, Kind::Main, String::new()),
+                (2, Kind::Suite, "tests".into()),
+                (5, Kind::Test, "tests/adds".into()),
+                (8, Kind::Test, "tests/async_one".into()),
+            ]
+        );
+        assert_eq!(
+            pick(&detect("#[test]\nfn x() {}", "crates/a/src/foo/bar.rs")),
+            [(1, Kind::Test, "foo/bar/x".into())]
+        );
+        assert!(detect("fn main() {}", "src/lib.rs").is_empty());
+    }
+
+    #[test]
+    fn js_describe_chains() {
+        let src = [
+            "describe('math', () => {",
+            "  it('adds', () => {});",
+            "  describe(\"nested\", () => {",
+            "    test.each([[1]])('n=%i', () => {});",
+            "  });",
+            "  test.skip(`subs`, () => {});",
+            "});",
+            "const item = items.find((x) => x);",
+            "test('top', () => {});",
+        ]
+        .join("\n");
+        let ts = detect(&src, "src/math.test.ts");
+        assert_eq!(
+            pick(&ts),
+            [
+                (0, Kind::Suite, "math".into()),
+                (1, Kind::Test, "math/adds".into()),
+                (2, Kind::Suite, "math/nested".into()),
+                (3, Kind::Test, "math/nested/n=%i".into()),
+                (5, Kind::Test, "math/subs".into()),
+                (8, Kind::Test, "top".into()),
+            ]
+        );
+        assert_eq!(js_name_pattern(&ts[1]), "^math adds$");
+        assert_eq!(js_name_pattern(&ts[3]), "^math nested n=.*$");
+        assert_eq!(js_name_pattern(&ts[0]), "^math");
+        assert!(detect("test('x', () => {})", "src/math.ts").is_empty());
+    }
+
+    #[test]
+    fn python_and_go() {
+        let src = "class TestCalc:\n    def test_add(self):\n        pass\ndef test_top():\n    pass\nclass Helper:\n    def test_no(self):\n        pass\nif __name__ == '__main__':\n    main()\n";
+        assert_eq!(
+            pick(&detect(src, "tests/test_calc.py")),
+            [
+                (0, Kind::Suite, "TestCalc".into()),
+                (1, Kind::Test, "TestCalc/test_add".into()),
+                (3, Kind::Test, "test_top".into()),
+                (8, Kind::Main, String::new()),
+            ]
+        );
+        let go = "package calc\n\nfunc TestAdd(t *testing.T) {\n\tt.Run(\"zero case\", func(t *testing.T) {})\n}\n";
+        assert_eq!(
+            pick(&detect(go, "calc_test.go")),
+            [(2, Kind::Test, "TestAdd".into()), (3, Kind::Test, "TestAdd/zero_case".into())]
+        );
+    }
+
+    #[test]
+    fn narrows_cargo_test_configs() {
+        let root = Path::new("/p");
+        let mut test = blank("cargo:test".into(), "test", "cargo", "cargo".into(), vec!["test".into()]);
+        test.is_test = true;
+        let configs = vec![test];
+        let src = "#[cfg(test)]\nmod tests {\n    #[test]\n    fn adds() {}\n}\n";
+        let ts = detect(src, "src/math.rs");
+        let c = target_config(root, &ts[1], "src/math.rs", &configs, src).unwrap();
+        assert_eq!(c.args, ["test", "--", "math::tests::adds", "--exact"]);
+        let c = target_config(root, &ts[0], "src/math.rs", &configs, src).unwrap();
+        assert_eq!(c.args, ["test", "--", "math::tests::"]);
+    }
+
+    #[test]
+    fn cargo_test_args_get_one_separator() {
+        let root = Path::new("/p");
+        let mut test =
+            blank("cargo:test".into(), "test", "cargo", "cargo".into(), vec!["test".into(), "--".into(), "-q".into()]);
+        test.is_test = true;
+        let configs = vec![test];
+        let src = "#[test]\nfn adds() {}\n";
+        let ts = detect(src, "tests/math.rs");
+        let c = target_config(root, &ts[0], "tests/math.rs", &configs, src).unwrap();
+        assert_eq!(c.args, ["test", "--test", "math", "--", "-q", "adds", "--exact"]);
+    }
+
+    #[test]
+    fn a_line_in_a_body_picks_the_enclosing_target() {
+        let names = |src: &str, rel: &str, line: usize| -> Vec<String> {
+            enclosing(src, rel, line).iter().map(|t| t.path.join("/")).collect()
+        };
+        let rust = [
+            "#[cfg(test)]",
+            "mod tests {",
+            "    #[test]",
+            "    fn adds(",
+            "        x: u8,",
+            "    ) {",
+            "        let s = \"}\";",
+            "        assert!(true);",
+            "    }",
+            "",
+            "    fn helper() {}",
+            "}",
+        ]
+        .join("\n");
+        assert_eq!(names(&rust, "src/math.rs", 7), ["math/tests/adds", "math/tests"]);
+        assert_eq!(names(&rust, "src/math.rs", 4), ["math/tests/adds", "math/tests"]);
+        assert_eq!(names(&rust, "src/math.rs", 10), ["math/tests"]);
+
+        let js = "describe('math', () => {\n  it('adds', () => {\n    expect(1).toBe(1);\n  });\n  it('one', fn);\n  const x = 1;\n});\n";
+        assert_eq!(names(js, "src/math.test.ts", 2), ["math/adds", "math"]);
+        assert_eq!(names(js, "src/math.test.ts", 5), ["math"]);
+
+        let py = "class TestCalc:\n    def test_add(self):\n        x = 1\n\n        assert x\n    def helper(self):\n        pass\n";
+        assert_eq!(names(py, "tests/test_calc.py", 4), ["TestCalc/test_add", "TestCalc"]);
+        assert_eq!(names(py, "tests/test_calc.py", 6), ["TestCalc"]);
+
+        let go = "package calc\n\nfunc TestAdd(t *testing.T) {\n\tt.Run(\"zero\", func(t *testing.T) {\n\t\tx := 0\n\t})\n\ty := 1\n}\n";
+        assert_eq!(names(go, "calc_test.go", 4), ["TestAdd/zero", "TestAdd"]);
+        assert_eq!(names(go, "calc_test.go", 6), ["TestAdd"]);
+        assert!(names(go, "calc_test.go", 0).is_empty());
+    }
+}

crates/ide-host/src/mcp/search.rs

@@ -0,0 +1,901 @@
+// Ported from JetBrains intellij-community plugins/mcp-server (mcpserver.toolsets/src/general/SearchToolset.kt,
+// SearchSymbolSupport.kt), Apache-2.0.
+//! Text, regex, file and symbol search.
+//!
+//! Coordinates are 1-based, end exclusive; columns count UTF-16 code units like
+//! the editor (one per character except emoji and other astral characters).
+
+use crate::mcp::tool::{Call, Output, Param, ParamType, Tool};
+use crate::mcp::util::{INDEXING_PARTIAL_RESULT_REASON, MEDIUM_TIMEOUT};
+use crate::ops::search::SearchEvent;
+use globset::{GlobBuilder, GlobSet, GlobSetBuilder};
+use ide_core::{CancellationToken, IdeError, IdeResult, Location, Range};
+use ide_search::{FileMask, FileMatches, SearchQuery, SearchScope, SearchSummary};
+use ide_vfs::EntryKind;
+use parking_lot::Mutex;
+use serde::Serialize;
+use serde_json::{Value, json};
+use std::cell::Cell;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+
+pub const MAX_RESULTS_UPPER_BOUND: usize = 5000;
+const DEFAULT_LIMIT: i64 = 1000;
+pub const SYMBOL_SEARCH_DEFAULT_LIMIT: i64 = 50;
+pub const SEARCH_TIMEOUT_PARTIAL_RESULT_REASON: &str =
+    "The search timed out after 10 s. Narrow the query or pass paths.";
+/// Symbols requested from the index per result when `paths` filters them afterwards.
+const SYMBOL_POOL_FACTOR: usize = 20;
+const MAX_SYMBOL_POOL: usize = 20_000;
+/// Matches Find in Files may report, per result asked for, when `paths` are filtered afterwards.
+const UNMASKED_MATCH_FACTOR: usize = 20;
+const MIN_UNMASKED_MATCHES: usize = 10_000;
+/// UTF-16 units of a line Find in Files reports (`ide_search`'s line window); matches
+/// outside the window of a longer line are left out.
+const LINE_WINDOW: usize = 500;
+
+const PATHS_DESCRIPTION: &str = "Optional list of project-relative glob patterns to filter results. Supports '!' \
+excludes. Trailing '/' expands to '**'. Patterns without '/' are treated as '**/pattern'. Empty strings are ignored.";
+const LIMIT_DESCRIPTION: &str = "Maximum number of results to return";
+
+pub fn tools() -> Vec<Tool> {
+    vec![search_text(), search_regex(), search_symbol(), search_file()]
+}
+
+fn search_text() -> Tool {
+    Tool::new(
+        "search_text",
+        "Searches for a text substring within project files.
+Use this tool for fast text search with match coordinates.
+Results include match coordinates when available (1-based line/column, end exclusive).
+
+Paths are glob patterns relative to the project root.
+Examples: [\"src/**\", \"!**/test/**\"], [\"**/*.kt\"], [\"foo/\"].",
+        |call| async move { text_search(call, false).await },
+    )
+    .param(Param::required("q", ParamType::String, "Text to search for"))
+    .param(Param::optional("paths", ParamType::StringList, PATHS_DESCRIPTION))
+    .param(Param::optional("limit", ParamType::Integer, LIMIT_DESCRIPTION))
+    .output(result_schema())
+}
+
+fn search_regex() -> Tool {
+    Tool::new(
+        "search_regex",
+        "Searches for regex matches within project files.
+Use this tool when you need regex search with match coordinates.
+Results include match coordinates when available (1-based line/column, end exclusive).
+The pattern uses Rust regex syntax and is case-sensitive; prefix `(?i)` to ignore case.
+
+Paths are glob patterns relative to the project root.
+Examples: [\"src/**\", \"!**/test/**\"], [\"**/*.kt\"], [\"foo/\"].",
+        |call| async move { text_search(call, true).await },
+    )
+    .param(Param::required("q", ParamType::String, "Regex pattern to search for"))
+    .param(Param::optional("paths", ParamType::StringList, PATHS_DESCRIPTION))
+    .param(Param::optional("limit", ParamType::Integer, LIMIT_DESCRIPTION))
+    .output(result_schema())
+}
+
+fn search_symbol() -> Tool {
+    Tool::new(
+        "search_symbol",
+        "Searches for symbols (classes, methods, fields).
+Use this tool for semantic lookup by identifier fragments.
+Results include match coordinates when available (1-based line/column, end exclusive).
+
+Paths are glob patterns relative to the project root.
+By default this searches project symbols only.
+If you don't find a suitable result, try again with include_external=true to search SDK and library symbols too.",
+        |call| async move { symbol_search(call).await },
+    )
+    .param(Param::required("q", ParamType::String, "Symbol query text"))
+    .param(Param::optional("paths", ParamType::StringList, PATHS_DESCRIPTION))
+    .param(Param::optional(
+        "include_external",
+        ParamType::Boolean,
+        "Whether to include SDK and library symbols. Disabled by default; if nothing suitable is found, try again \
+with include_external=true.",
+    ))
+    .param(Param::optional("limit", ParamType::Integer, LIMIT_DESCRIPTION))
+    .output(result_schema())
+}
+
+fn search_file() -> Tool {
+    Tool::new(
+        "search_file",
+        "Searches for files by glob pattern within the project.
+Use this tool when you need to match file paths using glob syntax.
+
+Glob patterns are relative to the project root.
+Examples: \"**/*.kt\", \"src/**/Foo*.java\", \"build.gradle.kts\".
+Patterns without '/' are treated as \"**/pattern\".
+Paths are optional additional glob filters relative to the project root.",
+        |call| async move { file_search(call).await },
+    )
+    .param(Param::required("q", ParamType::String, "Glob pattern to search for"))
+    .param(Param::optional("paths", ParamType::StringList, PATHS_DESCRIPTION))
+    .param(Param::optional(
+        "includeExcluded",
+        ParamType::Boolean,
+        "Whether to include excluded/ignored files in results",
+    ))
+    .param(Param::optional("limit", ParamType::Integer, LIMIT_DESCRIPTION))
+    .output(result_schema())
+}
+
+// --- results -------------------------------------------------------------------
+
+/// One hit. Every search tool returns these, so they share one schema: `search_file`
+/// fills only `filePath`, only `search_symbol` fills `name` and `container`.
+#[derive(Serialize, Debug, Default, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+struct SearchItem {
+    file_path: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    start_line: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    start_column: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    end_line: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    end_column: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    name: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    container: Option<String>,
+}
+
+impl SearchItem {
+    fn at(file_path: String, r: Range) -> Self {
+        Self {
+            file_path,
+            start_line: Some(r.start.line + 1),
+            start_column: Some(r.start.col + 1),
+            end_line: Some(r.end.line + 1),
+            end_column: Some(r.end.col + 1),
+            ..Default::default()
+        }
+    }
+}
+
+/// Empty fields are left out, so a search without hits is `{}`.
+#[derive(Serialize, Default)]
+#[serde(rename_all = "camelCase")]
+struct SearchResult {
+    #[serde(skip_serializing_if = "Vec::is_empty")]
+    items: Vec<SearchItem>,
+    #[serde(skip_serializing_if = "std::ops::Not::not")]
+    more: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    partial_result_reason: Option<&'static str>,
+}
+
+fn result_schema() -> Value {
+    let int = json!({ "type": "integer" });
+    let string = json!({ "type": "string" });
+    json!({
+        "type": "object",
+        "properties": {
+            "items": { "type": "array", "items": {
+                "type": "object",
+                "properties": {
+                    "filePath": string, "startLine": int, "startColumn": int, "endLine": int, "endColumn": int,
+                    "name": string, "container": string,
+                },
+                "required": ["filePath"],
+            } },
+            "more": { "type": "boolean" },
+            "partialResultReason": string,
+        },
+    })
+}
+
+fn limit(call: &Call, default: i64) -> IdeResult<usize> {
+    match call.opt_i64("limit")?.unwrap_or(default) {
+        n if n <= 0 => Err(IdeError::invalid("limit must be > 0")),
+        n => Ok((n as usize).min(MAX_RESULTS_UPPER_BOUND)),
+    }
+}
+
+fn query(call: &Call, empty: &str) -> IdeResult<String> {
+    let q = call.str("q")?;
+    if q.trim().is_empty() {
+        return Err(IdeError::invalid(empty));
+    }
+    Ok(q)
+}
+
+// --- path globs ----------------------------------------------------------------
+
+/// The `paths` argument: project-relative globs, `!` excludes.
+struct PathScope {
+    /// `None` when only excludes were given (everything is included).
+    include: Option<GlobSet>,
+    exclude: GlobSet,
+    /// The globs as `FileMask` masks for Find in Files (`{a,b}` expanded, as masks
+    /// split on commas), `None` when they cannot be expressed.
+    masks: Option<(Vec<String>, Vec<String>)>,
+}
+
+impl PathScope {
+    fn new(root: &Path, patterns: &[String]) -> IdeResult<Self> {
+        let (mut include, mut exclude) = (GlobSetBuilder::new(), GlobSetBuilder::new());
+        let (mut include_masks, mut exclude_masks) = (Vec::new(), Vec::new());
+        let mut has_include = false;
+        let mut maskable = true;
+        for raw in patterns {
+            let raw = raw.trim();
+            if raw.is_empty() {
+                continue;
+            }
+            let (negated, pattern) = match raw.strip_prefix('!') {
+                Some(rest) if rest.trim().is_empty() => return Err(IdeError::invalid("Exclude pattern is empty")),
+                Some(rest) => (true, rest.trim()),
+                None => (false, raw),
+            };
+            let mut glob = normalize_glob(pattern, root)?;
+            // A path naming an existing directory covers the files below it.
+            if index_of_glob_char(&glob).is_none() && root.join(&glob).is_dir() {
+                glob.push_str("/**");
+            }
+            let alternatives = expand_braces(&glob);
+            maskable &= alternatives.is_some();
+            let (set, masks) =
+                if negated { (&mut exclude, &mut exclude_masks) } else { (&mut include, &mut include_masks) };
+            set.add(build_glob(&glob)?);
+            masks.extend(alternatives.into_iter().flatten());
+            has_include |= !negated;
+        }
+        let build = |b: GlobSetBuilder| b.build().map_err(|e| IdeError::invalid(format!("Invalid glob pattern: {e}")));
+        Ok(Self {
+            include: if has_include { Some(build(include)?) } else { None },
+            exclude: build(exclude)?,
+            masks: maskable.then_some((include_masks, exclude_masks)),
+        })
+    }
+
+    fn is_all(&self) -> bool {
+        self.include.is_none() && self.exclude.is_empty()
+    }
+
+    /// `path` is project-relative with `/` (absolute outside the project).
+    fn matches(&self, path: &str) -> bool {
+        self.include.as_ref().is_none_or(|s| s.is_match(path)) && !self.exclude.is_match(path)
+    }
+}
+
+/// A glob as a project-relative pattern: `\` → `/`, leading `./` dropped, `dir/` → `dir/**`,
+/// `name` → `**/name`, and its leading directories (`..`, absolute paths) resolved against
+/// `root`. Errors when that points outside the project.
+fn normalize_glob(raw: &str, root: &Path) -> IdeResult<String> {
+    let mut value = raw.trim().replace('\\', "/");
+    if value.is_empty() {
+        return Err(IdeError::invalid("Glob pattern is empty"));
+    }
+    while let Some(rest) = value.strip_prefix("./") {
+        value = rest.to_owned();
+    }
+    if value.ends_with('/') {
+        let dir = value.trim_end_matches('/');
+        value = if dir.is_empty() { "**".into() } else { format!("{dir}/**") };
+    }
+    if !value.contains('/') {
+        value = format!("**/{value}");
+    }
+    let value = normalize_path_pattern(&value, root)?;
+    if value.is_empty() {
+        return Err(IdeError::invalid(format!("Invalid glob pattern: {raw}")));
+    }
+    Ok(value)
+}
+
+/// Resolves the whole directory segments before the first glob character against `root`.
+/// (JetBrains resolves up to the glob character itself, turning `src/Foo*.java` into
+/// `src/Foo/*.java`; only whole segments are resolved here.)
+fn normalize_path_pattern(pattern: &str, root: &Path) -> IdeResult<String> {
+    let outside = || {
+        IdeError::invalid(format!("Specified path '{pattern}' points to the location outside of the project directory"))
+    };
+    let prefix_len = match index_of_glob_char(pattern) {
+        None => pattern.len(),
+        Some(i) => pattern[..i].rfind('/').map_or(0, |slash| slash + 1),
+    };
+    let prefix = pattern[..prefix_len].trim_end_matches('/');
+    if prefix.is_empty() {
+        if is_absolute_pattern(pattern) {
+            return Err(outside());
+        }
+        return Ok(pattern.to_owned());
+    }
+    let prefix_path = Path::new(prefix);
+    let absolute = crate::mcp::tool::normalize(&if prefix_path.is_absolute() {
+        prefix_path.to_path_buf()
+    } else {
+        root.join(prefix_path)
+    });
+    let relative = relative_to_root(root, &absolute).ok_or_else(outside)?;
+    let suffix = pattern[prefix_len..].trim_start_matches('/');
+    Ok(match (relative.is_empty(), suffix.is_empty()) {
+        (true, _) => suffix.to_owned(),
+        (false, true) => relative,
+        (false, false) => format!("{relative}/{suffix}"),
+    })
+}
+
+/// `path` relative to `root` with `/`, also when one of them is spelled through a symlink
+/// (`/var` and `/private/var`); `None` outside `root`.
+fn relative_to_root(root: &Path, path: &Path) -> Option<String> {
+    let rel = match path.strip_prefix(root) {
+        Ok(rel) => rel.to_path_buf(),
+        Err(_) => {
+            let canon_root = dunce::canonicalize(root).ok()?;
+            let existing = path.ancestors().find(|a| a.exists())?;
+            let real = dunce::canonicalize(existing).ok()?.join(path.strip_prefix(existing).ok()?);
+            real.strip_prefix(&canon_root).ok()?.to_path_buf()
+        }
+    };
+    Some(rel.to_string_lossy().replace('\\', "/"))
+}
+
+fn is_absolute_pattern(pattern: &str) -> bool {
+    let b = pattern.as_bytes();
+    pattern.starts_with('/') || (b.len() >= 3 && b[1] == b':' && b[2] == b'/')
+}
+
+fn index_of_glob_char(pattern: &str) -> Option<usize> {
+    pattern.find(['*', '?', '[', ']', '{', '}'])
+}
+
+/// At most this many masks per glob from expanding its `{a,b}` groups.
+const MAX_BRACE_ALTERNATIVES: usize = 64;
+
+/// `glob` with its `{a,b}` groups expanded into separate globs without commas, for
+/// `FileMask` (which splits on them). `None` for nested groups, braces or commas in a
+/// character class, a comma outside a group, an unbalanced brace, or too many results.
+fn expand_braces(glob: &str) -> Option<Vec<String>> {
+    let mut out = vec![String::new()];
+    let mut chars = glob.chars();
+    let mut in_class = false;
+    while let Some(c) = chars.next() {
+        match c {
+            '{' | '}' | ',' if in_class => return None,
+            '[' => {
+                in_class = true;
+                out.iter_mut().for_each(|o| o.push(c));
+            }
+            ']' => {
+                in_class = false;
+                out.iter_mut().for_each(|o| o.push(c));
+            }
+            '{' => {
+                let mut group = String::new();
+                loop {
+                    match chars.next()? {
+                        '}' => break,
+                        '{' | '[' | ']' => return None,
+                        g => group.push(g),
+                    }
+                }
+                let options: Vec<&str> = group.split(',').collect();
+                if out.len() * options.len() > MAX_BRACE_ALTERNATIVES {
+                    return None;
+                }
+                out = out.iter().flat_map(|o| options.iter().map(move |a| format!("{o}{a}"))).collect();
+            }
+            '}' | ',' => return None,
+            _ => out.iter_mut().for_each(|o| o.push(c)),
+        }
+    }
+    (!in_class).then_some(out)
+}
+
+/// `**/` matches zero or more directories; case follows the file system (insensitive on
+/// macOS and Windows, like Find in Files' masks).
+fn build_glob(glob: &str) -> IdeResult<globset::Glob> {
+    GlobBuilder::new(glob)
+        .literal_separator(true)
+        .backslash_escape(false)
+        .case_insensitive(cfg!(any(target_os = "macos", target_os = "windows")))
+        .build()
+        .map_err(|_| IdeError::invalid(format!("Invalid glob pattern: {glob}")))
+}
+
+// --- text / regex --------------------------------------------------------------
+
+/// A match before it becomes a [`SearchItem`]; 1-based, end exclusive.
+struct TextHit {
+    file_path: String,
+    line: u32,
+    column: u32,
+    end_line: u32,
+    end_column: u32,
+}
+
+async fn text_search(call: Call, is_regex: bool) -> IdeResult<Output> {
+    let pattern = query(&call, if is_regex { "Regex pattern is empty" } else { "Search text is empty" })?;
+    let limit = limit(&call, DEFAULT_LIMIT)?;
+    let scope = PathScope::new(call.root(), &call.str_list("paths")?)?;
+    // Globs Find in Files cannot take are applied afterwards, so the engine must not
+    // stop at `limit` matches the filter may drop.
+    let (masks, max_matches) = match scope.masks.clone() {
+        // One more than asked tells whether there are more.
+        Some(masks) => (masks, (limit + 1) as u32),
+        // Bounded all the same (as the symbol pool): past it the result reports `more`.
+        None => {
+            let budget = ((limit + 1) * UNMASKED_MATCH_FACTOR).max(MIN_UNMASKED_MATCHES);
+            (Default::default(), u32::try_from(budget).unwrap_or(u32::MAX))
+        }
+    };
+    let (include, exclude) = masks;
+    let query = SearchQuery {
+        pattern: pattern.clone(),
+        is_regex,
+        case_sensitive: true,
+        whole_word: false,
+        include,
+        exclude,
+        scope: SearchScope::Project,
+        max_matches,
+        context: Default::default(),
+    };
+    if is_regex && let Err(e) = ide_search::match_ranges("", &query) {
+        return Err(IdeError::invalid(format!("Invalid regex pattern: {pattern} ({})", e.message)));
+    }
+    let (files, summary, timed_out) = run_search(&call, query.clone()).await?;
+    // Content roots outside the project are reported by absolute path.
+    let mut files: Vec<(String, FileMatches)> =
+        files.into_iter().map(|f| (call.display(&f.path.0), f)).filter(|(path, _)| scope.matches(path)).collect();
+    files.sort_by(|a, b| a.0.cmp(&b.0));
+    // Only these can match a line break.
+    let may_span = is_regex || pattern.contains('\n');
+    let mut hits = Vec::new();
+    let mut spanning = Vec::new();
+    let host = call.host();
+    for (path, file) in &files {
+        if hits.len() > limit {
+            break;
+        }
+        // Find in Files keeps a window of very long lines and drops the matches outside it:
+        // such lines are matched again in the file's whole text.
+        let long = |m: &ide_search::LineMatch| m.text_offset > 0 || m.text.encode_utf16().count() + 1 >= LINE_WINDOW;
+        let whole = if file.matches.iter().any(long) {
+            crate::ops::fs::read_text(&host, call.window(), file.path.0.clone())
+                .await
+                .ok()
+                .and_then(|text| Some((ide_search::match_ranges(&text, &query).ok()?, text)))
+        } else {
+            None
+        };
+        for m in &file.matches {
+            if let Some((ranges, text)) = &whole
+                && long(m)
+            {
+                hits.extend(line_hits(path, text, ranges, m.line));
+                continue;
+            }
+            let line_end = m.text_offset + m.text.encode_utf16().count() as u32;
+            for &(a, b) in &m.ranges {
+                let (a, b) = (m.text_offset + a, m.text_offset + b);
+                if may_span && b == line_end && hits.len() < limit {
+                    spanning.push((hits.len(), file.path.0.clone()));
+                }
+                hits.push(TextHit {
+                    file_path: path.clone(),
+                    line: m.line + 1,
+                    column: a + 1,
+                    end_line: m.line + 1,
+                    end_column: b + 1,
+                });
+            }
+        }
+    }
+    let more = hits.len() > limit || summary.limit_hit || timed_out;
+    hits.truncate(limit);
+    extend_spanning(&call, &query, &mut hits, spanning).await;
+    let items = hits
+        .into_iter()
+        .map(|h| SearchItem {
+            file_path: h.file_path,
+            start_line: Some(h.line),
+            start_column: Some(h.column),
+            end_line: Some(h.end_line),
+            end_column: Some(h.end_column),
+            ..Default::default()
+        })
+        .collect();
+    let partial_result_reason = timed_out.then_some(SEARCH_TIMEOUT_PARTIAL_RESULT_REASON);
+    Output::json(SearchResult { items, more, partial_result_reason })
+}
+
+/// The matches of `ranges` (byte ranges in `text`) that start on 0-based `line`, with their
+/// real end (on a later line for a match spanning lines).
+fn line_hits(path: &str, text: &str, ranges: &[(usize, usize)], line: u32) -> Vec<TextHit> {
+    let starts: Vec<usize> = std::iter::once(0).chain(text.match_indices('\n').map(|(i, _)| i + 1)).collect();
+    let Some(&line_start) = starts.get(line as usize) else { return Vec::new() };
+    let line_end = starts.get(line as usize + 1).map_or(text.len(), |s| s - 1);
+    let column = |at: usize| -> (u32, u32) {
+        let l = starts.partition_point(|&s| s <= at) - 1;
+        (l as u32 + 1, text[starts[l]..at].encode_utf16().count() as u32 + 1)
+    };
+    let first = ranges.partition_point(|r| r.0 < line_start);
+    ranges[first..]
+        .iter()
+        .take_while(|r| r.0 <= line_end)
+        .map(|&(a, b)| {
+            let (end_line, end_column) = column(b);
+            TextHit { file_path: path.to_owned(), line: line + 1, column: column(a).1, end_line, end_column }
+        })
+        .collect()
+}
+
+/// A file's path, text, line start offsets and match byte ranges.
+type FileText = (PathBuf, String, Vec<usize>, Vec<(usize, usize)>);
+
+/// Find in Files reports only the first line of a match that spans lines: matches
+/// ending at a line end get their real end from matching the file's text again.
+async fn extend_spanning(call: &Call, query: &SearchQuery, hits: &mut [TextHit], spanning: Vec<(usize, PathBuf)>) {
+    let host = call.host();
+    let mut current: Option<FileText> = None;
+    for (i, path) in spanning {
+        if current.as_ref().is_none_or(|(p, ..)| p != &path) {
+            let Ok(text) = crate::ops::fs::read_text(&host, call.window(), path.clone()).await else { continue };
+            let Ok(ranges) = ide_search::match_ranges(&text, query) else { continue };
+            let starts = std::iter::once(0).chain(text.match_indices('\n').map(|(i, _)| i + 1)).collect();
+            current = Some((path, text, starts, ranges));
+        }
+        let Some((_, text, starts, ranges)) = &current else { continue };
+        let h = &mut hits[i];
+        let Some(&line_start) = starts.get(h.line as usize - 1) else { continue };
+        let Some(start) = byte_at(&text[line_start..], h.column - 1).map(|b| line_start + b) else { continue };
+        let Ok(found) = ranges.binary_search_by_key(&start, |r| r.0) else { continue };
+        let end = ranges[found].1;
+        let end_line = starts.partition_point(|&s| s <= end) - 1;
+        h.end_line = end_line as u32 + 1;
+        h.end_column = text[starts[end_line]..end].encode_utf16().count() as u32 + 1;
+    }
+}
+
+/// The byte offset of UTF-16 column `col` in `line`.
+fn byte_at(line: &str, col: u32) -> Option<usize> {
+    let mut units = 0;
+    for (i, c) in line.char_indices() {
+        if units == col {
+            return Some(i);
+        }
+        units += c.len_utf16() as u32;
+    }
+    (units == col).then_some(line.len())
+}
+
+/// Runs Find in Files for at most [`MEDIUM_TIMEOUT`], cancelling it when the call is
+/// cancelled. Returns what was found and whether the time ran out.
+async fn run_search(call: &Call, query: SearchQuery) -> IdeResult<(Vec<FileMatches>, SearchSummary, bool)> {
+    let host = call.host();
+    let request = crate::mcp::tool::request_id();
+    let files = Arc::new(Mutex::new(Vec::new()));
+    let done = Arc::new(Mutex::new(None));
+    let emit: crate::ops::Emit<SearchEvent> = {
+        let (files, done) = (files.clone(), done.clone());
+        Arc::new(move |event| match event {
+            SearchEvent::File { file } => files.lock().push(file),
+            SearchEvent::Done { summary } => *done.lock() = Some(summary),
+        })
+    };
+    let search = crate::ops::search::start(&host, call.window(), request, query, emit);
+    tokio::pin!(search);
+    let mut timed_out = false;
+    tokio::select! {
+        r = &mut search => r?,
+        _ = call.cancel.cancelled() => {
+            host.cancel_request(request);
+            let _ = search.await;
+            return Err(IdeError::cancelled());
+        }
+        _ = tokio::time::sleep(MEDIUM_TIMEOUT) => {
+            host.cancel_request(request);
+            let _ = search.await;
+            timed_out = true;
+        }
+    }
+    let summary = done.lock().take().unwrap_or_default();
+    if summary.cancelled && !timed_out {
+        return Err(IdeError::cancelled());
+    }
+    let files = std::mem::take(&mut *files.lock());
+    Ok((files, summary, timed_out))
+}
+
+// --- files ---------------------------------------------------------------------
+
+async fn file_search(call: Call) -> IdeResult<Output> {
+    let q = query(&call, "Glob pattern is empty")?;
+    let limit = limit(&call, DEFAULT_LIMIT)?;
+    let scope = PathScope::new(call.root(), &call.str_list("paths")?)?;
+    let include_excluded = call.flag("includeExcluded", false)?;
+    let glob = GlobSetBuilder::new()
+        .add(build_glob(&normalize_glob(&q, call.root())?)?)
+        .build()
+        .map_err(|_| IdeError::invalid(format!("Invalid glob pattern: {q}")))?;
+    // Ignored names and "Exclude files" patterns, which `read_dir` does not flag.
+    let excludes = if include_excluded { None } else { Some(FileMask::new(&[], &call.project().search_excludes())?) };
+    let root = call.root().to_path_buf();
+    // The project folder and the content roots outside it.
+    let roots: Vec<PathBuf> = std::iter::once(root.clone())
+        .chain(call.project().content_roots().into_iter().filter(|r| relative_to_root(&root, r).is_none()))
+        .collect();
+    let host = call.host();
+    let walk = Walk {
+        host: host.clone(),
+        window: call.window().to_owned(),
+        root,
+        include_excluded,
+        excludes,
+        glob,
+        scope,
+        limit,
+        cancel: call.cancel.clone(),
+        deadline: Instant::now() + MEDIUM_TIMEOUT,
+        timed_out: Cell::new(false),
+    };
+    let (paths, more, timed_out) = host
+        .blocking(move || {
+            let mut found = Vec::new();
+            let more = roots.iter().any(|base| walk.dir(base, base, &mut found));
+            if walk.cancel.is_cancelled() {
+                return Err(IdeError::cancelled());
+            }
+            Ok((found, more, walk.timed_out.get()))
+        })
+        .await?;
+    let items = paths.into_iter().map(|file_path| SearchItem { file_path, ..Default::default() }).collect();
+    let partial_result_reason = timed_out.then_some(SEARCH_TIMEOUT_PARTIAL_RESULT_REASON);
+    Output::json(SearchResult { items, more, partial_result_reason })
+}
+
+struct Walk {
+    host: Arc<crate::Host>,
+    window: String,
+    root: PathBuf,
+    include_excluded: bool,
+    excludes: Option<FileMask>,
+    glob: GlobSet,
+    scope: PathScope,
+    limit: usize,
+    cancel: CancellationToken,
+    deadline: Instant,
+    timed_out: Cell<bool>,
+}
+
+impl Walk {
+    /// Collects matching files under `dir` (inside the walked root `base`) depth first in
+    /// name order; true when it stopped early: more than `limit` match or the time ran out.
+    fn dir(&self, dir: &Path, base: &Path, found: &mut Vec<String>) -> bool {
+        let Ok(mut entries) = tokio::runtime::Handle::current().block_on(crate::ops::fs::read_dir(
+            &self.host,
+            &self.window,
+            dir.to_path_buf(),
+        )) else {
+            return false;
+        };
+        entries.sort_by(|a, b| a.name.cmp(&b.name));
+        for entry in entries {
+            if self.cancel.is_cancelled() {
+                return false;
+            }
+            if Instant::now() >= self.deadline {
+                self.timed_out.set(true);
+                return true;
+            }
+            if entry.name == ".git" || (!self.include_excluded && (entry.ignored || entry.excluded)) {
+                continue;
+            }
+            let Ok(in_base) = entry.path.strip_prefix(base) else { continue };
+            if self.excludes.as_ref().is_some_and(|m| !m.matches(&in_base.to_string_lossy().replace('\\', "/"))) {
+                continue;
+            }
+            match entry.kind {
+                // Symlinked directories are not followed (they may loop).
+                EntryKind::Dir => {
+                    if self.dir(&entry.path, base, found) {
+                        return true;
+                    }
+                }
+                EntryKind::File => {
+                    // Files of content roots outside the project go by absolute path.
+                    let path = relative_to_root(&self.root, &entry.path)
+                        .unwrap_or_else(|| entry.path.to_string_lossy().into_owned());
+                    if self.glob.is_match(&path) && self.scope.matches(&path) {
+                        if found.len() == self.limit {
+                            return true;
+                        }
+                        found.push(path);
+                    }
+                }
+                _ => {}
+            }
+        }
+        false
+    }
+}
+
+// --- symbols -------------------------------------------------------------------
+
+async fn symbol_search(call: Call) -> IdeResult<Output> {
+    let started = Instant::now();
+    let q = query(&call, "Search query is empty")?;
+    let limit = limit(&call, SYMBOL_SEARCH_DEFAULT_LIMIT)?;
+    let scope = PathScope::new(call.root(), &call.str_list("paths")?)?;
+    let external = call.flag("include_external", false)?;
+    let host = call.host();
+    let project = call.project().clone();
+    let indexing_before = project.index.status().indexing;
+    let pool = if scope.is_all() { limit + 1 } else { ((limit + 1) * SYMBOL_POOL_FACTOR).min(MAX_SYMBOL_POOL) };
+    let found = {
+        let (project, q) = (project.clone(), q.clone());
+        host.blocking(move || Ok(project.index.find_symbols(&q, ide_index::SymbolFilter::All, pool))).await?
+    };
+    let mut items: Vec<SearchItem> = found
+        .into_iter()
+        .filter(|s| scope.matches(&s.rel_path))
+        .map(|s| SearchItem {
+            name: Some(s.name),
+            container: s.container.filter(|c| !c.is_empty()),
+            ..SearchItem::at(s.rel_path, s.range)
+        })
+        .collect();
+    let mut timed_out = false;
+    if external && items.len() <= limit {
+        let budget = MEDIUM_TIMEOUT.saturating_sub(started.elapsed());
+        let (symbols, out_of_time) = workspace_symbols(&call, &q, budget).await;
+        timed_out = out_of_time;
+        for (name, container, location) in symbols {
+            let path = location.uri.clone().unwrap_or_else(|| call.display(&location.path));
+            // Project files obey `paths`; library symbols are what was asked for.
+            let inside = location.uri.is_none() && !Path::new(&path).is_absolute();
+            if inside && !scope.matches(&path) {
+                continue;
+            }
+            let item = SearchItem {
+                name: Some(name),
+                container: container.filter(|c| !c.is_empty()),
+                ..SearchItem::at(path, location.range)
+            };
+            if !items
+                .iter()
+                .any(|e| e.name == item.name && e.file_path == item.file_path && e.start_line == item.start_line)
+            {
+                items.push(item);
+            }
+            if items.len() > limit {
+                break;
+            }
+        }
+    }
+    let more = items.len() > limit || timed_out;
+    items.truncate(limit);
+    let indexing = indexing_before || project.index.status().indexing;
+    let partial_result_reason = if indexing {
+        Some(INDEXING_PARTIAL_RESULT_REASON)
+    } else {
+        timed_out.then_some(SEARCH_TIMEOUT_PARTIAL_RESULT_REASON)
+    };
+    Output::json(SearchResult { items, more, partial_result_reason })
+}
+
+/// The language servers' workspace symbols, and whether `budget` ran out first; empty
+/// when none runs or they fail.
+async fn workspace_symbols(call: &Call, q: &str, budget: Duration) -> (Vec<(String, Option<String>, Location)>, bool) {
+    let host = call.host();
+    let request = crate::mcp::tool::request_id();
+    let symbols = crate::ops::lsp::lsp_workspace_symbols(&host, call.window(), request, q.to_owned());
+    tokio::pin!(symbols);
+    let result = tokio::select! {
+        r = tokio::time::timeout(budget, &mut symbols) => r.ok(),
+        _ = call.cancel.cancelled() => None,
+    };
+    match result {
+        Some(Ok(symbols)) => (symbols.into_iter().map(|s| (s.name, s.container, s.location)).collect(), false),
+        Some(Err(e)) => {
+            tracing::debug!("MCP search_symbol: workspace symbols: {e}");
+            (Vec::new(), false)
+        }
+        None => {
+            host.cancel_request(request);
+            let _ = symbols.await;
+            (Vec::new(), !call.cancel.is_cancelled())
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn root() -> (tempfile::TempDir, PathBuf) {
+        let dir = tempfile::tempdir().unwrap();
+        let root = dunce::canonicalize(dir.path()).unwrap().join("project");
+        std::fs::create_dir_all(root.join("subdir1/nested")).unwrap();
+        (dir, root)
+    }
+
+    fn scope(root: &Path, p: &[&str]) -> PathScope {
+        PathScope::new(root, &p.iter().map(|s| s.to_string()).collect::<Vec<_>>()).unwrap()
+    }
+
+    #[test]
+    fn normalizes_globs() {
+        let (_dir, root) = root();
+        let n = |p: &str| normalize_glob(p, &root);
+        assert_eq!(n("*.rs").unwrap(), "**/*.rs");
+        assert_eq!(n("./foo/bar.txt").unwrap(), "foo/bar.txt");
+        assert_eq!(n("foo/").unwrap(), "foo/**");
+        assert_eq!(n("/").unwrap(), "**/**");
+        assert_eq!(n("./src/**/*.ts").unwrap(), "src/**/*.ts");
+        assert_eq!(n("src\\gen\\*.rs").unwrap(), "src/gen/*.rs");
+        assert_eq!(n("src/a/../Foo*.java").unwrap(), "src/Foo*.java");
+        assert_eq!(n(&root.join("sub/Foo.kt").to_string_lossy()).unwrap(), "sub/Foo.kt");
+        assert_eq!(n(&format!("{}/**/*.kt", root.display())).unwrap(), "**/*.kt");
+        for outside in ["../outside/**", "/elsewhere/*.rs", "/**"] {
+            let err = n(outside).unwrap_err().message;
+            assert!(err.contains("outside of the project directory"), "{outside}: {err}");
+        }
+        assert!(n("  ").unwrap_err().message.contains("Glob pattern is empty"));
+    }
+
+    #[test]
+    fn expands_brace_groups() {
+        let e = |g: &str| expand_braces(g);
+        assert_eq!(e("src/**/*.rs"), Some(vec!["src/**/*.rs".to_owned()]));
+        assert_eq!(e("src/**/*.{ts,tsx}"), Some(vec!["src/**/*.ts".to_owned(), "src/**/*.tsx".to_owned()]));
+        assert_eq!(e("{a,b}/*.{x,y}"), Some(["a/*.x", "a/*.y", "b/*.x", "b/*.y"].map(String::from).to_vec()));
+        assert_eq!(e("a{,.bak}"), Some(vec!["a".to_owned(), "a.bak".to_owned()]));
+        assert_eq!(e("[{]x"), None);
+        assert_eq!(e("{a,{b,c}}"), None);
+        assert_eq!(e("a,b"), None);
+        assert_eq!(e("{a,b"), None);
+        assert_eq!(e("a}"), None);
+        assert_eq!(e(&"{a,b}".repeat(7)), None);
+        assert_eq!(e(&"{a,b}".repeat(6)).map(|v| v.len()), Some(64));
+    }
+
+    #[test]
+    fn utf16_columns_to_bytes() {
+        assert_eq!(byte_at("a😀b", 0), Some(0));
+        assert_eq!(byte_at("a😀b", 3), Some(5));
+        assert_eq!(byte_at("a😀b", 4), Some(6));
+        assert_eq!(byte_at("a😀b", 2), None);
+        assert_eq!(byte_at("ab", 5), None);
+    }
+
+    #[test]
+    fn path_scopes() {
+        let (_dir, root) = root();
+        let root = root.as_path();
+        assert!(scope(root, &[]).is_all());
+        assert!(scope(root, &["", " "]).is_all());
+        let s = scope(root, &["subdir1/**", "!**/*.java"]);
+        assert!(s.matches("subdir1/foo.txt"));
+        assert!(!s.matches("subdir1/foo.java"));
+        assert!(!s.matches("subdir2/foo.txt"));
+        let s = scope(root, &["subdir1/**", "!subdir1/excluded/**"]);
+        assert!(s.matches("subdir1/foo.txt") && !s.matches("subdir1/excluded/foo.txt"));
+        // An existing directory covers the files below it; other names match files only.
+        let s = scope(root, &["subdir1/nested"]);
+        assert!(s.matches("subdir1/nested/foo.txt") && !s.matches("subdir1/other/foo.txt"));
+        let s = scope(root, &["!gen"]);
+        assert!(s.matches("src/gen/a.rs") && !s.matches("src/gen"));
+        let s = scope(root, &["*.rs"]);
+        assert!(s.matches("a.rs") && s.matches("x/y/a.rs") && !s.matches("a.ts"));
+        assert!(s.matches("/abs/content/root/a.rs"));
+        let s = scope(root, &["!*.md"]);
+        assert!(s.matches("a.rs") && !s.matches("docs/a.md"));
+        assert!(scope(root, &["*.{rs,ts}"]).masks.is_some());
+        assert!(scope(root, &["*.{rs,{ts,js}}"]).masks.is_none());
+        let err = |p: &str| PathScope::new(root, &[p.to_owned()]).err().unwrap().message;
+        assert!(err("a[").contains("Invalid glob pattern"));
+        assert!(err("!").contains("Exclude pattern is empty"));
+        assert!(err("../x/**").contains("outside of the project directory"));
+    }
+}

crates/ide-host/src/mcp/symbols.rs

@@ -0,0 +1,264 @@
+//! Quick Documentation through the project's language services.
+use super::tool::{Call, Output, Param, ParamType, Tool};
+use ide_core::{IdeError, IdeResult, Pos, Range};
+use ide_lsp::types::GotoKind;
+use serde::Serialize;
+use serde_json::json;
+use std::path::Path;
+
+pub fn get_symbol_info() -> Tool {
+    Tool::new("get_symbol_info", "Retrieves information about the symbol at the specified position in the specified file.
+Provides the same information as the Quick Documentation feature of the IDE does (the language server's hover).
+
+This tool is useful for getting information about the symbol at the specified position in the specified file.
+The information may include the symbol's name, signature, type, documentation, etc. It depends on a particular language.
+
+If the position has a reference to a symbol the tool will return a piece of code with the declaration of the symbol if possible.
+
+Use this tool to understand symbols declaration, semantics, where it's declared, etc.", get_info)
+    .param(Param::required("filePath", ParamType::String, "Path relative to the project root"))
+    .param(Param::required("line", ParamType::Integer, "1-based line number"))
+    .param(Param::required("column", ParamType::Integer, "1-based UTF-16 column number"))
+}
+
+async fn get_info(call: Call) -> IdeResult<Output> {
+    let path = call.resolve_readable(&call.str("filePath")?).await?;
+    let line = call.opt_i64("line")?.ok_or_else(|| IdeError::invalid("missing line"))?;
+    let col = call.opt_i64("column")?.ok_or_else(|| IdeError::invalid("missing column"))?;
+    let project = call.project.clone();
+    let p = path.clone();
+    struct Document(std::sync::Arc<crate::Project>, ide_core::DocId);
+    impl Drop for Document {
+        fn drop(&mut self) {
+            self.0.documents.close(self.1);
+        }
+    }
+    let (text, document) = call
+        .host
+        .blocking(move || {
+            let text = project.text_of(&p)?;
+            let doc = project.documents.open(&p)?;
+            Ok((text, Document(project, doc.id)))
+        })
+        .await?;
+    let doc = document.1;
+    if line < 1 || line > u32::MAX as i64 {
+        return Err(IdeError::invalid("line is out of bounds"));
+    }
+    let line_text = usize::try_from(line.saturating_sub(1))
+        .ok()
+        .and_then(|l| text.split('\n').nth(l))
+        .ok_or_else(|| IdeError::invalid("Line number is out of bounds of the document"))?;
+    if col < 1 || col as usize > line_text.encode_utf16().count() + 1 {
+        return Err(IdeError::invalid("Column number is out of bounds of the document"));
+    }
+    let pos = Pos::new((line - 1) as u32, (col - 1) as u32);
+    let word = word_at(line_text, char_column(line_text, col as u32));
+    let mut output = json!({"documentation":""});
+    let work = async {
+        let hover = call.project.lsp.hover(doc, pos, call.cancel.clone()).await;
+        let definitions = call.project.lsp.goto(doc, pos, GotoKind::Definition).await;
+        Ok::<_, IdeError>((hover, definitions))
+    };
+    let result = tokio::select! {
+        result = tokio::time::timeout(std::time::Duration::from_secs(20), work) => result,
+        _ = call.cancel.cancelled() => return Err(IdeError::cancelled()),
+    };
+    match result {
+        Ok(Ok((hover, definitions))) => {
+            if let Ok(Some(hover)) = hover {
+                output["documentation"] = hover.contents.value.into();
+            }
+            if let Ok(definitions) = definitions
+                && let Some(location) = definitions.iter().find(|l| l.uri.is_none())
+                && let Some(info) = symbol_info(&call, &location.path, word.clone(), location.range, 1)
+            {
+                output["symbolInfo"] = serde_json::to_value(info).map_err(|e| IdeError::internal(e.to_string()))?;
+            }
+        }
+        Ok(Err(e)) => {
+            output["partialResultReason"] = e.message.into();
+        }
+        Err(_) => {
+            output["partialResultReason"] = "The language server did not answer in time; retry later.".into();
+        }
+    }
+    if output.get("symbolInfo").is_none()
+        && let Some(word) = word
+    {
+        let project = call.project.clone();
+        let path = path.clone();
+        let found = call
+            .host
+            .blocking(move || {
+                let mut symbols = project.index.symbols_named(&word, None, 50);
+                symbols.sort_by_key(|s| s.path != path);
+                Ok(symbols.into_iter().next())
+            })
+            .await?;
+        if let Some(symbol) = found
+            && let Some(info) = symbol_info(&call, &symbol.path, Some(symbol.name), symbol.range, 1)
+        {
+            output["symbolInfo"] = serde_json::to_value(info).map_err(|e| IdeError::internal(e.to_string()))?;
+        }
+    }
+    if call.project.index.status().indexing {
+        output["partialResultReason"] = super::util::INDEXING_PARTIAL_RESULT_REASON.into();
+    }
+    Ok(Output::text(output.to_string()))
+}
+
+/// The 1-based character index of 1-based UTF-16 `column` in `line`.
+fn char_column(line: &str, column: u32) -> u32 {
+    let mut units = 0u32;
+    let mut chars = 0u32;
+    for c in line.chars() {
+        if units + 1 >= column {
+            break;
+        }
+        units += c.len_utf16() as u32;
+        chars += 1;
+    }
+    chars + 1
+}
+
+fn is_word(c: char) -> bool {
+    c.is_alphanumeric() || c == '_' || c == '$'
+}
+
+/// The identifier at (or just before) 1-based character `column` of `line`.
+fn word_at(line: &str, column: u32) -> Option<String> {
+    let chars: Vec<char> = line.chars().collect();
+    let mut at = (column as usize).saturating_sub(1).min(chars.len());
+    if !chars.get(at).is_some_and(|c| is_word(*c)) {
+        if at > 0 && is_word(chars[at - 1]) {
+            at -= 1;
+        } else {
+            return None;
+        }
+    }
+    let start = (0..=at).rev().take_while(|i| is_word(chars[*i])).last()?;
+    let end = (at..chars.len()).take_while(|i| is_word(chars[*i])).last()? + 1;
+    Some(chars[start..end].iter().collect())
+}
+
+/// Lines of comments and annotations above a declaration that count as part of it.
+const MAX_LEADING_LINES: usize = 30;
+
+/// JetBrains' `SymbolInfo`.
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+struct SymbolInfo {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    name: Option<String>,
+    declaration_text: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    declaration_file: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    declaration_line: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    language: Option<String>,
+}
+
+/// JetBrains' `getElementSymbolInfo` over a declaration's name range: from the comments and
+/// annotations right above it to the line where the name ends, plus `extra_lines`.
+fn symbol_info(
+    call: &Call,
+    path: &Path,
+    name: Option<String>,
+    name_range: Range,
+    extra_lines: u32,
+) -> Option<SymbolInfo> {
+    let project = call.project();
+    let text = project.text_of(path).ok()?;
+    let text = text.replace("\r\n", "\n");
+    let lines: Vec<&str> = text.split('\n').collect();
+    let name_line = name_range.start.line as usize;
+    if name_line >= lines.len() {
+        return None;
+    }
+    let language = project.languages.detect(path, lines.first().copied());
+    let config = project.languages.get(&language);
+    let line_comment = config.as_ref().and_then(|c| c.line_comment.clone());
+    let mut start = name_line;
+    while start > 0
+        && name_line - start < MAX_LEADING_LINES
+        && leads_declaration(lines[start - 1], line_comment.as_deref())
+    {
+        start -= 1;
+    }
+    let end = (name_range.end.line.max(name_range.start.line) as usize + extra_lines as usize).min(lines.len() - 1);
+    Some(SymbolInfo {
+        name,
+        declaration_text: format!("<…>\n{}\n<…>", lines[start..=end].join("\n")),
+        declaration_file: Some(call.display(path)),
+        declaration_line: Some(name_line as u32 + 1),
+        language: config.map(|c| c.name),
+    })
+}
+
+/// Doc comments, comments and annotations / attributes / decorators belong to the declaration below.
+fn leads_declaration(line: &str, line_comment: Option<&str>) -> bool {
+    let t = line.trim_start();
+    if t.is_empty() {
+        return false;
+    }
+    ["//", "/*", "*", "#[", "#![", "@"].iter().any(|p| t.starts_with(p))
+        || line_comment.is_some_and(|c| !c.is_empty() && t.starts_with(c))
+}
+
+pub fn find_references() -> Tool {
+    Tool::new("find_references", "Find references using the language service and the IDE's project index. Positions are 1-based UTF-16. Reports incomplete results when analysis is still running.", |call| async move {
+        let path = call.resolve_readable(&call.str("filePath")?).await?;
+        let line = call.opt_i64("line")?.ok_or_else(|| IdeError::invalid("missing line"))?;
+        let column = call.opt_i64("column")?.ok_or_else(|| IdeError::invalid("missing column"))?;
+        let project = call.project.clone();
+        let (doc, text) = call.host.blocking(move || {
+            let text = project.text_of(&path)?;
+            let doc = project.documents.open(&path)?;
+            Ok((doc.id, text))
+        }).await?;
+        struct Close(std::sync::Arc<crate::Project>, ide_core::DocId);
+        impl Drop for Close { fn drop(&mut self) { self.0.documents.close(self.1); } }
+        let _close = Close(call.project.clone(), doc);
+        let pos = mcp_position(&text, line, column)?;
+        let request = super::tool::request_id();
+        let work = crate::ops::lsp::lsp_references(&call.host, &call.window, request, doc, pos, call.flag("includeDeclaration", true)?, true, false, crate::ops::Channel::new(|_| {}));
+        tokio::pin!(work);
+        let result = tokio::select! {
+            result = &mut work => result?,
+            _ = call.cancel.cancelled() => { call.host.cancel_request(request); let _ = work.await; return Err(IdeError::cancelled()); }
+            _ = tokio::time::sleep(std::time::Duration::from_secs(60)) => { call.host.cancel_request(request); let _ = work.await; return Err(IdeError::unavailable("references timed out; retry when analysis finishes")); }
+        };
+        let mut value = serde_json::to_value(&result).map_err(|e| IdeError::internal(e.to_string()))?;
+        // Convert every Location range at this boundary, including declarations.
+        fn positions(value: &mut serde_json::Value) {
+            match value {
+                serde_json::Value::Object(map) => {
+                    if let (Some(line), Some(col)) = (map.get("line").and_then(|v| v.as_u64()), map.get("col").and_then(|v| v.as_u64())) {
+                        map.insert("line".into(), (line + 1).into()); map.insert("col".into(), (col + 1).into());
+                    } else { for v in map.values_mut() { positions(v); } }
+                }
+                serde_json::Value::Array(items) => { for v in items { positions(v); } }
+                _ => {}
+            }
+        }
+        positions(&mut value);
+        Output::json(value)
+    })
+    .param(Param::required("filePath", ParamType::String, "Path relative to the project root"))
+    .param(Param::required("line", ParamType::Integer, "1-based line"))
+    .param(Param::required("column", ParamType::Integer, "1-based UTF-16 column"))
+    .param(Param::optional("includeDeclaration", ParamType::Boolean, "Include declarations (default true)"))
+}
+
+fn mcp_position(text: &str, line: i64, column: i64) -> IdeResult<Pos> {
+    if line < 1 || line > u32::MAX as i64 || column < 1 || column > u32::MAX as i64 {
+        return Err(IdeError::invalid("line and column must be positive 1-based positions"));
+    }
+    let row = text.split('\n').nth((line - 1) as usize).ok_or_else(|| IdeError::invalid("line is out of bounds"))?;
+    if column as usize > row.encode_utf16().count() + 1 {
+        return Err(IdeError::invalid("column is out of bounds"));
+    }
+    Ok(Pos::new((line - 1) as u32, (column - 1) as u32))
+}

crates/ide-host/src/mcp/tool.rs

@@ -0,0 +1,297 @@
+use crate::{Host, Project};
+use ide_core::{CancellationToken, IdeError, IdeResult};
+use serde::Serialize;
+use serde_json::{Value, json};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+pub struct Call {
+    pub client: String,
+    pub tool: String,
+    pub host: Arc<Host>,
+    pub project: Arc<Project>,
+    pub window: String,
+    pub args: Value,
+    pub cancel: CancellationToken,
+}
+
+impl Call {
+    pub fn opt_str(&self, name: &str) -> IdeResult<Option<String>> {
+        self.args
+            .get(name)
+            .filter(|v| !v.is_null())
+            .map(|v| v.as_str().map(str::to_owned).ok_or_else(|| IdeError::invalid(format!("{name} must be a string"))))
+            .transpose()
+    }
+    pub fn str_map(&self, name: &str) -> IdeResult<Vec<(String, String)>> {
+        self.args
+            .get(name)
+            .and_then(Value::as_object)
+            .ok_or_else(|| IdeError::invalid(format!("{name} must be an object")))?
+            .iter()
+            .map(|(k, v)| {
+                v.as_str()
+                    .map(|v| (k.clone(), v.to_owned()))
+                    .ok_or_else(|| IdeError::invalid(format!("{name} must contain strings")))
+            })
+            .collect()
+    }
+    pub fn resolve_inside(&self, path: &str) -> IdeResult<PathBuf> {
+        resolve_inside(self.root(), path)
+    }
+    pub async fn resolve_writable(&self, path: &str) -> IdeResult<PathBuf> {
+        let path = self.resolve_inside(path)?;
+        self.check_writable(&path).await?;
+        Ok(path)
+    }
+    pub async fn check_writable(&self, path: &Path) -> IdeResult<()> {
+        self.project.require_trust()?;
+        ensure_inside(self.root(), path)
+    }
+    pub async fn ask(&self, request: ide_core::event::McpUiRequest) -> IdeResult<()> {
+        self.host.mcp_requests.ask(self, request).await
+    }
+    pub async fn confirm(&self, subject: &str, detail: Option<String>) -> IdeResult<()> {
+        self.ask(ide_core::event::McpUiRequest::Confirm {
+            client: self.client.clone(),
+            tool: self.tool.clone(),
+            subject: subject.into(),
+            project: self.root().to_string_lossy().into_owned(),
+            detail,
+        })
+        .await?;
+        self.project.require_trust()
+    }
+    pub fn host(&self) -> Arc<Host> {
+        self.host.clone()
+    }
+    pub fn project(&self) -> &Arc<Project> {
+        &self.project
+    }
+    pub fn root(&self) -> &Path {
+        &self.project.root
+    }
+    pub fn window(&self) -> &str {
+        &self.window
+    }
+    pub fn str(&self, name: &str) -> IdeResult<String> {
+        self.args
+            .get(name)
+            .and_then(Value::as_str)
+            .map(str::to_owned)
+            .ok_or_else(|| IdeError::invalid(format!("missing or invalid argument `{name}`")))
+    }
+    pub fn opt_i64(&self, name: &str) -> IdeResult<Option<i64>> {
+        self.args
+            .get(name)
+            .map(|v| v.as_i64().ok_or_else(|| IdeError::invalid(format!("{name} must be an integer"))))
+            .transpose()
+    }
+    pub fn flag(&self, name: &str, default: bool) -> IdeResult<bool> {
+        self.args
+            .get(name)
+            .map(|v| v.as_bool().ok_or_else(|| IdeError::invalid(format!("{name} must be a boolean"))))
+            .unwrap_or(Ok(default))
+    }
+    pub fn str_list(&self, name: &str) -> IdeResult<Vec<String>> {
+        match self.args.get(name) {
+            None => Ok(Vec::new()),
+            Some(Value::Array(values)) => values
+                .iter()
+                .map(|v| {
+                    v.as_str()
+                        .map(str::to_owned)
+                        .ok_or_else(|| IdeError::invalid(format!("{name} must contain strings")))
+                })
+                .collect(),
+            _ => Err(IdeError::invalid(format!("{name} must be an array"))),
+        }
+    }
+    pub fn display(&self, path: &Path) -> String {
+        path.strip_prefix(self.root()).unwrap_or(path).to_string_lossy().replace('\\', "/")
+    }
+    pub async fn resolve_readable(&self, path: &str) -> IdeResult<PathBuf> {
+        let root = self.root().to_path_buf();
+        let mut roots = self.project.content_roots();
+        roots.extend(self.host.mcp_reports.libraries(&self.host.mcp_windows(self.root())));
+        roots.extend(
+            self.project
+                .settings
+                .effective()
+                .project_structure
+                .libraries
+                .iter()
+                .flat_map(|l| l.sources.iter().chain(&l.classes).chain(&l.javadocs))
+                .map(|p| self.root().join(p)),
+        );
+        let path = path.to_owned();
+        self.host
+            .blocking(move || {
+                let path = if path.starts_with("file://") {
+                    ide_lsp::uri_to_path(&path).ok_or_else(|| IdeError::invalid("invalid file URL"))?
+                } else {
+                    PathBuf::from(path)
+                };
+                let path = if path.is_absolute() { path } else { root.join(path) };
+                let (local, entry) =
+                    ide_vfs::split_archive_path(&path).map_or((path.clone(), None), |(p, e)| (p, Some(e)));
+                let real = if let Ok(real) = dunce::canonicalize(&local) {
+                    real
+                } else {
+                    let parent =
+                        local.ancestors().find(|p| p.exists()).ok_or_else(|| IdeError::not_found("path not found"))?;
+                    normalize(
+                        &dunce::canonicalize(parent)?
+                            .join(local.strip_prefix(parent).map_err(|e| IdeError::invalid(e.to_string()))?),
+                    )
+                };
+                if !std::iter::once(root).chain(roots).any(|r| {
+                    let r = ide_vfs::split_archive_path(&r).map_or(r.clone(), |(archive, _)| archive);
+                    dunce::canonicalize(r).is_ok_and(|r| real.starts_with(r))
+                }) {
+                    return Err(IdeError::invalid("path is outside the project's content roots"));
+                }
+                Ok(entry.map_or_else(|| real.clone(), |entry| PathBuf::from(format!("{}!/{entry}", real.display()))))
+            })
+            .await
+    }
+}
+
+pub struct Output(pub String);
+impl Output {
+    pub fn text(text: impl Into<String>) -> Self {
+        Self(text.into())
+    }
+    pub fn json(value: impl Serialize) -> IdeResult<Self> {
+        serde_json::to_string(&value).map(Self).map_err(|e| IdeError::internal(e.to_string()))
+    }
+}
+
+#[derive(Clone, Copy)]
+pub enum ParamType {
+    String,
+    Integer,
+    Boolean,
+    StringList,
+    StringMap,
+}
+pub struct Param {
+    name: &'static str,
+    kind: ParamType,
+    description: &'static str,
+    required: bool,
+}
+impl Param {
+    pub fn required(name: &'static str, kind: ParamType, description: &'static str) -> Self {
+        Self { name, kind, description, required: true }
+    }
+    pub fn optional(name: &'static str, kind: ParamType, description: &'static str) -> Self {
+        Self { name, kind, description, required: false }
+    }
+}
+
+type Handler = Arc<dyn Fn(Call) -> futures::future::BoxFuture<'static, IdeResult<Output>> + Send + Sync>;
+pub struct Tool {
+    pub metadata: ide_mcp::Tool,
+    pub handler: Handler,
+}
+impl Tool {
+    pub fn new<F, Fut>(name: &str, description: &str, handler: F) -> Self
+    where
+        F: Fn(Call) -> Fut + Send + Sync + 'static,
+        Fut: Future<Output = IdeResult<Output>> + Send + 'static,
+    {
+        Self {
+            metadata: ide_mcp::Tool {
+                name: name.into(),
+                description: description.into(),
+                read_only: true,
+                destructive: false,
+                output_schema: None,
+                input_schema: json!({ "type": "object", "properties": {
+                    "projectPath": { "type": "string", "description": "Any directory inside an open project. Optional when only one project is open." }
+                }, "required": [] }),
+            },
+            handler: Arc::new(move |call| Box::pin(handler(call))),
+        }
+    }
+    pub fn write(mut self) -> Self {
+        self.metadata.read_only = false;
+        self
+    }
+    pub fn param(mut self, param: Param) -> Self {
+        let mut schema = match param.kind {
+            ParamType::String => json!({"type":"string"}),
+            ParamType::Integer => json!({"type":"integer"}),
+            ParamType::Boolean => json!({"type":"boolean"}),
+            ParamType::StringMap => json!({"type":"object","additionalProperties":{"type":"string"}}),
+            ParamType::StringList => json!({"type":"array","items":{"type":"string"}}),
+        };
+        schema["description"] = param.description.into();
+        self.metadata.input_schema["properties"][param.name] = schema;
+        if param.required {
+            self.metadata.input_schema["required"].as_array_mut().unwrap().push(param.name.into());
+        }
+        self
+    }
+    pub fn output(mut self, schema: Value) -> Self {
+        self.metadata.output_schema = Some(schema);
+        self
+    }
+}
+
+pub fn normalize(path: &Path) -> PathBuf {
+    let mut out = PathBuf::new();
+    for part in path.components() {
+        match part {
+            std::path::Component::CurDir => {}
+            std::path::Component::ParentDir => {
+                out.pop();
+            }
+            p => out.push(p.as_os_str()),
+        }
+    }
+    out
+}
+
+pub fn request_id() -> ide_core::RequestId {
+    static NEXT: std::sync::atomic::AtomicU32 = std::sync::atomic::AtomicU32::new(0x8000_0000);
+    ide_core::RequestId(NEXT.fetch_add(1, std::sync::atomic::Ordering::Relaxed))
+}
+
+/// Resolve existing ancestors too, so symlinks cannot escape the project.
+pub fn resolve_inside(root: &Path, raw: &str) -> IdeResult<PathBuf> {
+    let path = if raw.starts_with("file://") {
+        ide_lsp::uri_to_path(raw).ok_or_else(|| IdeError::invalid("invalid file URL"))?
+    } else {
+        PathBuf::from(raw)
+    };
+    let path = if path.is_absolute() { path } else { root.join(path) };
+    if path.components().any(|c| c.as_os_str().to_string_lossy().eq_ignore_ascii_case(".git")) {
+        return Err(IdeError::invalid("VCS metadata cannot be changed"));
+    }
+    let path = normalize(&path);
+    let ancestor =
+        path.ancestors().find(|p| p.exists()).ok_or_else(|| IdeError::invalid("path has no existing parent"))?;
+    let mut real = dunce::canonicalize(ancestor)?;
+    let suffix = path.strip_prefix(ancestor).map_err(|e| IdeError::invalid(e.to_string()))?;
+    if !suffix.as_os_str().is_empty() {
+        real.push(suffix);
+    }
+    let root = dunce::canonicalize(root)?;
+    if !real.starts_with(&root) {
+        return Err(IdeError::invalid("path is outside the project"));
+    }
+    if real
+        .strip_prefix(&root)
+        .unwrap()
+        .components()
+        .any(|c| c.as_os_str().to_string_lossy().eq_ignore_ascii_case(".git"))
+    {
+        return Err(IdeError::invalid("VCS metadata cannot be changed"));
+    }
+    Ok(real)
+}
+pub fn ensure_inside(root: &Path, path: &Path) -> IdeResult<()> {
+    resolve_inside(root, &path.to_string_lossy()).map(|_| ())
+}

crates/ide-host/src/mcp/util.rs

@@ -0,0 +1,69 @@
+// Ported from JetBrains intellij-community plugins/mcp-server (src/com/intellij/mcpserver/util/fs.util.kt,
+// util/text.util.kt, toolsets/Constants.kt), Apache-2.0.
+//! Helpers shared by the tools: the strings and timeouts of JetBrains' `Constants`,
+//! resolving the paths `read_file` accepts, and text truncation.
+
+use crate::mcp::tool::Call;
+use ide_core::{IdeError, IdeResult};
+use std::path::PathBuf;
+use std::time::Duration;
+
+pub const RELATIVE_PATH_IN_PROJECT_DESCRIPTION: &str = "Path relative to the project root";
+pub const FILE_PATH_DESCRIPTION: &str = "Path to the file. Supports project-relative paths, paths with '..', \
+absolute paths, archive entries like '/path/lib.jar!/pkg/Foo.java', and URLs such as 'file://' and 'jar://'. \
+Any path returned from the other tools can be passed as is (e.g. paths from 'search_*' tools).";
+pub const TIMEOUT_MILLISECONDS_DESCRIPTION: &str = "Timeout in milliseconds";
+pub const TIMED_OUT_DESCRIPTION: &str = "Indicates whether the operation was timed out. 'true' value may mean that \
+the results may be incomplete or partial. 'false', 'null' or missing value means that the operation has not been \
+timed out.";
+pub const MEDIUM_TIMEOUT: Duration = Duration::from_secs(10);
+pub const INDEXING_PARTIAL_RESULT_REASON: &str =
+    "Project indexing was in progress; results may be incomplete — retry once indexing completes.";
+
+/// Whether `path` starts with a URL scheme (`file://`, `jar://`, `jrt://` …).
+pub fn looks_like_vfs_url(path: &str) -> bool {
+    path.find("://")
+        .is_some_and(|i| i > 0 && path[..i].chars().all(|c| c.is_ascii_alphanumeric() || matches!(c, '+' | '-' | '.')))
+}
+
+/// Resolves `read_file`'s `file_path`: project-relative or absolute paths, archive entries
+/// (`/lib.jar!/pkg/Foo.java`) and `file://` / `jar://` URLs, within known content or library roots.
+pub async fn resolve_read_file(call: &Call, file_path: &str) -> IdeResult<PathBuf> {
+    let normalized = file_path.trim().replace('\\', "/");
+    if normalized.is_empty() {
+        return Err(IdeError::invalid("file_path is empty"));
+    }
+    let missing = || IdeError::not_found(format!("File {file_path} doesn't exist or can't be opened"));
+    let local = if looks_like_vfs_url(&normalized) {
+        let (scheme, rest) = normalized.split_once("://").unwrap_or_default();
+        match scheme.to_ascii_lowercase().as_str() {
+            // `file://` URLs are percent-decoded by `resolve`.
+            "file" => normalized.clone(),
+            "jar" => rest.to_owned(),
+            "jrt" => {
+                return Err(IdeError::invalid(format!(
+                    "File {file_path} can't be opened: OpenIDEA does not read jrt:// (Java runtime image) entries"
+                )));
+            }
+            _ => return Err(missing()),
+        }
+    } else {
+        normalized
+    };
+    let path = call.resolve_readable(&local).await?;
+    match ide_vfs::split_archive_path(&path) {
+        Some((archive, entry)) => {
+            if !archive.is_file() {
+                return Err(missing());
+            }
+            if entry.is_empty() || ide_vfs::read_archive_dir(&archive, &entry).is_ok() {
+                return Err(IdeError::invalid(format!("File {file_path} is a directory")));
+            }
+            ide_vfs::probe(&path).map_err(|_| missing())?;
+        }
+        None if path.is_dir() => return Err(IdeError::invalid(format!("File {file_path} is a directory"))),
+        None if !path.is_file() && call.project().documents.by_path(&path).is_none() => return Err(missing()),
+        None => {}
+    }
+    Ok(path)
+}

crates/ide-host/src/mcp/vcs.rs

@@ -0,0 +1,362 @@
+// Ported from JetBrains intellij-community plugins/mcp-server
+// (mcpserver.vcs/src/com/intellij/mcpserver/toolsets/vcs/VcsToolset.kt), Apache-2.0.
+//! Version control: repositories and git status.
+
+use crate::mcp::tool::{Call, Output, Param, ParamType, Tool};
+use ide_core::{IdeError, IdeResult};
+use serde_json::{Value, json};
+use std::path::{Path, PathBuf};
+
+const STATUS_DEFAULT_LIMIT: i64 = 1000;
+
+pub fn tools() -> Vec<Tool> {
+    vec![get_repositories(), git_status(), git_diff()]
+}
+
+/// `path` with symbolic links resolved (macOS `/var` is `/private/var`), as given when it
+/// does not exist.
+fn canonical(path: &Path) -> PathBuf {
+    dunce::canonicalize(path).unwrap_or_else(|_| path.to_path_buf())
+}
+
+/// A path relative to the project root with `/`; empty for the root itself. Either may
+/// name the other through a symbolic link.
+fn relative_to(root: &Path, path: &Path) -> String {
+    let rel = match path.strip_prefix(root) {
+        Ok(rel) => Some(rel.to_path_buf()),
+        Err(_) => canonical(path).strip_prefix(canonical(root)).ok().map(Path::to_path_buf),
+    };
+    match rel {
+        Some(rel) => rel.to_string_lossy().replace('\\', "/"),
+        None => path.to_string_lossy().into_owned(),
+    }
+}
+
+fn relative_to_project(call: &Call, path: &Path) -> String {
+    relative_to(call.root(), path)
+}
+
+/// The repository whose roots contain `path` most specifically (paths compared canonically).
+fn innermost_repo<T>(repos: Vec<(PathBuf, T)>, path: &Path) -> Option<(PathBuf, T)> {
+    let path = canonical(path);
+    repos.into_iter().filter(|r| path.starts_with(canonical(&r.0))).max_by_key(|r| canonical(&r.0).components().count())
+}
+
+// Read tools must never invoke repository-configured executables, including in Restricted Mode.
+fn read_command(git: &str, root: &Path) -> std::process::Command {
+    let mut command = std::process::Command::new(git);
+    command
+        .current_dir(root)
+        .args([
+            "-c",
+            "core.fsmonitor=false",
+            "-c",
+            "core.hooksPath=",
+            "-c",
+            "diff.external=",
+            "-c",
+            "core.attributesFile=",
+            "-c",
+            "submodule.recurse=false",
+            "-c",
+            "color.ui=false",
+        ])
+        .env("GIT_NO_LAZY_FETCH", "1")
+        .env("GIT_TERMINAL_PROMPT", "0")
+        .env("GIT_OPTIONAL_LOCKS", "0")
+        .env_remove("GIT_EXTERNAL_DIFF")
+        .env_remove("GIT_DIR")
+        .env_remove("GIT_WORK_TREE")
+        .env_remove("GIT_INDEX_FILE");
+    ide_core::process::prepare(&mut command);
+    command
+}
+
+/// The branch HEAD is on (unborn too); `None` when HEAD is detached or git fails.
+fn read_branch(git: &str, root: &Path) -> Option<String> {
+    let mut cmd = read_command(git, root);
+    cmd.args(["symbolic-ref", "--short", "-q", "HEAD"]);
+    ide_core::process::prepare(&mut cmd);
+    let out = cmd.output().ok().filter(|o| o.status.success())?;
+    Some(String::from_utf8_lossy(&out.stdout).trim().to_owned()).filter(|b| !b.is_empty())
+}
+
+fn get_repositories() -> Tool {
+    Tool::new(
+        "get_repositories",
+        "Retrieves the list of VCS roots in the project.
+This is useful to detect all repositories in a multi-repository project.
+In OpenIDEA each root also tells its current `branch` (absent when HEAD is detached), `headCommit` and a merge, \
+rebase or cherry-pick in progress (`operationInProgress`).",
+        |call| async move {
+            let host = call.host();
+            let window = call.window.clone();
+            let roots = call.host.blocking(move || crate::ops::vcs::vcs_roots(&host, &window)).await?;
+            let list: Vec<Value> = roots
+                .into_iter()
+                .map(|r| {
+                    let mut v =
+                        json!({ "pathRelativeToProject": relative_to_project(&call, &r.root), "vcsName": "Git" });
+                    if let Some(head) = r.head {
+                        v["branch"] = head.into();
+                    }
+                    if let Some(commit) = r.head_commit {
+                        v["headCommit"] = commit.into();
+                    }
+                    if let Some(op) = r.operation {
+                        v["operationInProgress"] = op.into();
+                    }
+                    v
+                })
+                .collect();
+            Output::json(json!({ "roots": list }))
+        },
+    )
+}
+
+/// One entry of `git status --porcelain -z`.
+#[derive(Debug, PartialEq)]
+struct StatusEntry {
+    index: char,
+    work_tree: char,
+    path: String,
+    orig_path: Option<String>,
+}
+
+impl StatusEntry {
+    fn untracked(&self) -> bool {
+        self.index == '?'
+    }
+    fn ignored(&self) -> bool {
+        self.index == '!'
+    }
+    fn conflicted(&self) -> bool {
+        matches!((self.index, self.work_tree), ('D', 'D') | ('A', 'U') | ('U', _) | ('A', 'A') | ('D', 'U'))
+    }
+    fn staged(&self) -> bool {
+        !self.conflicted() && !matches!(self.index, ' ' | '?' | '!')
+    }
+    fn unstaged(&self) -> bool {
+        !self.conflicted() && !matches!(self.work_tree, ' ' | '?' | '!')
+    }
+}
+
+fn parse_status(out: &str) -> Vec<StatusEntry> {
+    let mut fields = out.split('\0').filter(|f| !f.is_empty());
+    let mut entries = Vec::new();
+    while let Some(field) = fields.next() {
+        let mut chars = field.chars();
+        let (Some(index), Some(work_tree)) = (chars.next(), chars.next()) else { continue };
+        let path = field.get(3..).unwrap_or_default().to_owned();
+        let orig_path = matches!(index, 'R' | 'C').then(|| fields.next().map(str::to_owned)).flatten();
+        entries.push(StatusEntry { index, work_tree, path, orig_path });
+    }
+    entries
+}
+
+fn git_executable(call: &Call) -> String {
+    let settings = if call.project.is_trusted() {
+        call.project.settings.effective()
+    } else {
+        call.host.global_settings.effective()
+    };
+    let exe = settings.vcs.git.executable.trim().to_owned();
+    if exe.is_empty() { "git".to_owned() } else { exe }
+}
+
+/// `git status` of the repository at `root`, paths relative to it.
+fn read_status(git: &str, root: &Path, untracked: bool, ignored: bool) -> IdeResult<Vec<StatusEntry>> {
+    let mut cmd = read_command(git, root);
+    cmd.args(["-c", "core.quotepath=false", "status", "--porcelain", "-z", "--find-renames"]);
+    // git refuses `--ignored=matching` with `--untracked-files=no`: untracked files are dropped below.
+    cmd.arg(if untracked || ignored { "--untracked-files=all" } else { "--untracked-files=no" });
+    if ignored {
+        cmd.arg("--ignored=matching");
+    }
+    ide_core::process::prepare(&mut cmd);
+    let out = cmd.output().map_err(|e| IdeError::unavailable(format!("cannot run git: {e}")))?;
+    if !out.status.success() {
+        return Err(IdeError::internal(String::from_utf8_lossy(&out.stderr).trim().to_owned()));
+    }
+    let mut entries = parse_status(&String::from_utf8_lossy(&out.stdout));
+    entries.retain(|e| untracked || !e.untracked());
+    Ok(entries)
+}
+
+/// A git repository in the project, for paths outside the repositories IDEA knows: the
+/// closest folder with `.git` from `start` up to the project root.
+fn find_git_root(root: &Path, start: &Path) -> Option<PathBuf> {
+    let (root, start) = (canonical(root), canonical(start));
+    let mut current = if start.is_dir() { start.as_path() } else { start.parent().unwrap_or(&start) };
+    while current.starts_with(&root) {
+        if current.join(".git").exists() {
+            return Some(current.to_path_buf());
+        }
+        current = current.parent()?;
+    }
+    None
+}
+
+fn git_status() -> Tool {
+    Tool::new(
+        "git_status",
+        "Retrieves Git status for one or more repositories in the current project.
+Returns porcelain-style index/worktree status codes and summary counters.
+By default all Git repositories are returned.",
+        |call| async move {
+            let include_untracked = call.flag("includeUntracked", true)?;
+            let include_ignored = call.flag("includeIgnored", false)?;
+            let limit = call.opt_i64("limit")?.unwrap_or(STATUS_DEFAULT_LIMIT);
+            if limit <= 0 {
+                return Err(IdeError::invalid("limit must be > 0"));
+            }
+            let limit = limit as usize;
+            let host = call.host();
+            let h = host.clone();
+            let w = call.window.clone();
+            let repos: Vec<(PathBuf, Option<String>)> = host
+                .blocking(move || crate::ops::vcs::vcs_roots(&h, &w))
+                .await?
+                .into_iter()
+                .map(|r| (r.root.into_path_buf(), r.head))
+                .collect();
+            let wanted = call.opt_str("repositoryPathRelativeToProject")?;
+            let git = git_executable(&call);
+            let mut roots: Vec<(PathBuf, Option<String>)> = match &wanted {
+                None => repos,
+                Some(wanted) => {
+                    let path = call.resolve_inside(wanted)?;
+                    // The innermost repository containing the path.
+                    match innermost_repo(repos, &path) {
+                        Some(repo) => vec![repo],
+                        None => match find_git_root(call.root(), &path) {
+                            Some(root) => {
+                                // JetBrains reads the branch of any repository it reports.
+                                let (git, dir) = (git.clone(), root.clone());
+                                let branch = host.blocking(move || Ok(read_branch(&git, &dir))).await?;
+                                vec![(root, branch)]
+                            }
+                            None => {
+                                return Err(IdeError::not_found(format!("No git repository found for path: {wanted}")));
+                            }
+                        },
+                    }
+                }
+            };
+            roots.sort_by_key(|r| relative_to_project(&call, &r.0));
+            let mut repositories = Vec::new();
+            for (root, branch) in roots {
+                let rel = relative_to_project(&call, &root);
+                let (git, dir) = (git.clone(), root.clone());
+                let entries = host
+                    .blocking(move || read_status(&git, &dir, include_untracked, include_ignored))
+                    .await
+                    .map_err(|e| {
+                        IdeError::internal(format!("Failed to get git status for repository '{rel}': {}", e.message))
+                    })?;
+                let count = |f: fn(&StatusEntry) -> bool| entries.iter().filter(|e| f(e)).count();
+                let listed: Vec<Value> = entries
+                    .iter()
+                    .take(limit)
+                    .map(|e| {
+                        let mut v = json!({
+                            "pathRelativeToRepository": e.path.trim_end_matches('/'),
+                            "indexStatus": e.index.to_string(),
+                            "workTreeStatus": e.work_tree.to_string(),
+                        });
+                        if let Some(orig) = &e.orig_path {
+                            v["originalPathRelativeToRepository"] = orig.clone().into();
+                        }
+                        v
+                    })
+                    .collect();
+                repositories.push(json!({
+                    "repositoryPathRelativeToProject": rel,
+                    "currentBranch": branch,
+                    "isClean": entries.is_empty(),
+                    "totalEntries": entries.len(),
+                    "hasMoreEntries": entries.len() > listed.len(),
+                    "stagedCount": count(StatusEntry::staged),
+                    "unstagedCount": count(StatusEntry::unstaged),
+                    "untrackedCount": count(StatusEntry::untracked),
+                    "ignoredCount": count(StatusEntry::ignored),
+                    "conflictedCount": count(StatusEntry::conflicted),
+                    "entries": listed,
+                }));
+            }
+            Output::json(json!({ "repositories": repositories }))
+        },
+    )
+    .param(Param::optional(
+        "repositoryPathRelativeToProject",
+        ParamType::String,
+        "Optional path relative to project root used to select a single containing repository",
+    ))
+    .param(Param::optional("includeUntracked", ParamType::Boolean, "Whether to include untracked files"))
+    .param(Param::optional("includeIgnored", ParamType::Boolean, "Whether to include ignored files"))
+    .param(Param::optional("limit", ParamType::Integer, "Maximum number of entries returned per repository"))
+}
+
+fn git_diff() -> Tool {
+    Tool::new("git_diff", "Read a Git diff for a file or the working tree. staged=true compares the index with HEAD; otherwise compares disk with the index. Unsaved editor text is not part of this diff.", |call| async move {
+        let wanted = call.opt_str("repositoryPathRelativeToProject")?;
+        let path = wanted.as_deref().map(|p| call.resolve_inside(p)).transpose()?.unwrap_or_else(|| call.root().to_path_buf());
+        let root = find_git_root(call.root(), &path).ok_or_else(|| IdeError::not_found("No git repository found"))?;
+        let file = call.opt_str("filePath")?.map(|p| call.resolve_inside(&p)).transpose()?;
+        if file.as_ref().is_some_and(|p| !p.starts_with(&root)) { return Err(IdeError::invalid("file is outside the repository")); }
+        let staged = call.flag("staged", false)?;
+        let git = git_executable(&call);
+        let cancel = call.cancel.clone();
+        let text = call.host.blocking(move || {
+            let mut cmd = read_command(&git, &root);
+            cmd.args(["--no-pager", "diff", "--no-ext-diff", "--no-textconv"]);
+            if staged { cmd.arg("--cached"); }
+            cmd.arg("--");
+            if let Some(file) = file { cmd.arg(file.strip_prefix(&root).map_err(|e| IdeError::invalid(e.to_string()))?); }
+            ide_core::process::prepare(&mut cmd);
+            if cancel.is_cancelled() { return Err(IdeError::cancelled()); }
+            let out = cmd.output()?;
+            if !out.status.success() { return Err(IdeError::unavailable(String::from_utf8_lossy(&out.stderr).trim())); }
+            Ok(String::from_utf8_lossy(&out.stdout).into_owned())
+        }).await?;
+        Ok(Output::text(text))
+    })
+    .param(Param::optional("repositoryPathRelativeToProject", ParamType::String, "Select the containing repository"))
+    .param(Param::optional("filePath", ParamType::String, "Optional project-relative file; omit for the working tree"))
+    .param(Param::optional("staged", ParamType::Boolean, "Show staged changes"))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_porcelain_z_with_renames() {
+        let out = "M  a.txt\0R  new.txt\0old.txt\0?? u.txt\0UU c.txt\0";
+        let e = parse_status(out);
+        assert_eq!(e.len(), 4);
+        assert_eq!(e[1].path, "new.txt");
+        assert_eq!(e[1].orig_path.as_deref(), Some("old.txt"));
+        assert!(e[0].staged() && !e[0].unstaged());
+        assert!(e[2].untracked() && !e[2].staged());
+        assert!(e[3].conflicted() && !e[3].staged() && !e[3].unstaged());
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn paths_through_a_symlinked_root_compare_canonically() {
+        // As macOS `/var` → `/private/var`: the project opened through the link, git reporting real paths.
+        let dir = tempfile::tempdir().unwrap();
+        let real = dunce::canonicalize(dir.path()).unwrap().join("real");
+        std::fs::create_dir_all(real.join("sub/.git")).unwrap();
+        std::fs::write(real.join("sub/f.txt"), "x").unwrap();
+        let link = dir.path().join("link");
+        std::os::unix::fs::symlink(&real, &link).unwrap();
+        assert_eq!(relative_to(&link, &real.join("sub")), "sub");
+        assert_eq!(relative_to(&real, &link.join("sub")), "sub");
+        assert_eq!(relative_to(&link, &link), "");
+        let repos = vec![(real.clone(), 1), (real.join("sub"), 2)];
+        assert_eq!(innermost_repo(repos, &link.join("sub/f.txt")).map(|r| r.1), Some(2));
+        assert_eq!(find_git_root(&link, &real.join("sub/f.txt")), Some(real.join("sub")));
+    }
+}

crates/ide-host/src/ops/debug.rs

@@ -75,8 +75,20 @@ pub async fn debug_start(host: &Host, window: &str, config: LaunchConfig) -> Ide
         config.extra_json = Some(extra.to_string());
     }
     let root = config.cwd.clone().map(PathBuf::from).unwrap_or_default();
+    let mut ruby_tools = Vec::new();
+    if config.adapter == "rdbg" {
+        let project_root = host.project(window).map(|p| p.root.clone()).unwrap_or_else(|_| root.clone());
+        let (dir, settings) = (root.clone(), settings.clone());
+        (config, ruby_tools) = host
+            .blocking(move || {
+                let tools = ide_sdk::ruby::debug_environment(&project_root, &dir, &settings, &mut config.env);
+                Ok((config, tools))
+            })
+            .await?;
+    }
     let custom = |command: &str| {
-        let path = ide_sdk::apply::tool_command(&root, &settings, command)?;
+        let path = ide_sdk::apply::tool_command(&root, &settings, command)
+            .or_else(|| ruby_tools.into_iter().find(|(name, _)| *name == command).map(|(_, path)| path))?;
         Some(path.to_string_lossy().into_owned())
     };
     host.require_trust(window)?;

crates/ide-host/src/ops/java.rs

@@ -235,11 +235,18 @@ pub async fn java_build_workspace(
     host: &Host,
     window: &str,
     module: PathBuf,
+    request: Option<RequestId>,
 ) -> IdeResult<ide_lsp::jdtls::JavaBuildStatus> {
     host.require_trust(window)?;
     let project = host.project(window)?;
     let module = project.root.join(module);
-    project.lsp.java_build(&module, &CancellationToken::new()).await
+    // HotSwap may cancel the compile (the request id is allocated by the caller).
+    let cancel = request.map_or_else(CancellationToken::new, |id| host.begin_request(id));
+    let result = project.lsp.java_build(&module, &cancel).await;
+    if let Some(id) = request {
+        host.end_request(id);
+    }
+    result
 }
 
 /// Commands of this module the remote server answers.
@@ -249,7 +256,9 @@ pub(crate) fn register(d: &mut Dispatcher) {
             .await
     });
     d.add("java_debug_server", |c| async move { java_debug_server(&c.host, &c.window, c.arg("module")?).await });
-    d.add("java_build_workspace", |c| async move { java_build_workspace(&c.host, &c.window, c.arg("module")?).await });
+    d.add("java_build_workspace", |c| async move {
+        java_build_workspace(&c.host, &c.window, c.arg("module")?, c.arg("request")?).await
+    });
 }
 
 #[cfg(test)]

crates/ide-host/src/ops/sdk.rs

@@ -207,7 +207,13 @@ pub async fn sdk_project_libraries(
     if cancel.is_cancelled() {
         return Err(IdeError::cancelled());
     }
-    Ok(ide_sdk::libraries::merge_groups([libraries.map_err(join_err)?, dependencies.map_err(join_err)?].concat()))
+    let groups =
+        ide_sdk::libraries::merge_groups([libraries.map_err(join_err)?, dependencies.map_err(join_err)?].concat());
+    if host.project(window).is_ok_and(|current| std::sync::Arc::ptr_eq(&current, &project)) {
+        host.mcp_reports
+            .set_libraries(window, groups.iter().flat_map(|g| g.roots.iter().map(|r| r.path.0.clone())).collect());
+    }
+    Ok(groups)
 }
 
 /// Looks up `names` (bare command names): `node_modules/.bin` above `near`, then the search path.

crates/ide-host/src/ops/vcs.rs

@@ -24,3 +24,37 @@ pub async fn status(host: &Host, window: &str) -> IdeResult<Vec<FileStatus>> {
 
 mod commands;
 pub use commands::*;
+
+fn check_worktree_removal(project_root: &std::path::Path, path: &std::path::Path) -> IdeResult<()> {
+    fn canonical_path(path: &std::path::Path) -> std::io::Result<std::path::PathBuf> {
+        let mut existing = path.to_path_buf();
+        let mut tail = Vec::new();
+        let mut real = loop {
+            match dunce::canonicalize(&existing) {
+                Ok(real) => break real,
+                Err(e) if e.kind() == std::io::ErrorKind::NotFound => {
+                    let Some(part) = existing.components().next_back() else { return Err(e) };
+                    tail.push(part.as_os_str().to_owned());
+                    if !existing.pop() {
+                        return Err(e);
+                    }
+                }
+                Err(e) => return Err(e),
+            }
+        };
+        // The project or worktree may already be gone; resolve its missing tail too.
+        for part in tail.into_iter().rev() {
+            if part == ".." {
+                real.pop();
+            } else if part != "." {
+                real.push(part);
+            }
+        }
+        Ok(real)
+    }
+
+    if canonical_path(project_root)?.starts_with(canonical_path(path)?) {
+        return Err(ide_core::IdeError::invalid("Cannot remove a worktree containing the open project."));
+    }
+    Ok(())
+}

crates/ide-host/src/ops/vcs/commands.rs

@@ -1041,6 +1041,12 @@ pub async fn vcs_remove_worktree(
     host.require_trust(window)?;
     let project = host.project(window)?;
     blocking(move || {
+        let path = if path.is_absolute() {
+            path
+        } else {
+            project.with_repo_at(repo.as_deref(), |r| Ok(r.root().join(&path)))?
+        };
+        check_worktree_removal(&project.root, &path)?;
         let result = project.with_repo_at(repo.as_deref(), |r| r.remove_worktree(&path, force));
         project.refresh_repositories();
         result

crates/ide-host/src/trust.rs

@@ -214,6 +214,8 @@ pub fn restricted_command_allowed(cmd: &str) -> bool {
         cmd,
         "app_info"
             | "app_build_info"
+            | "app_cli_install"
+            | "app_cli_uninstall"
             | "app_log_location"
             | "app_check_update"
             | "app_startup_update_check"
@@ -277,6 +279,7 @@ pub fn restricted_command_allowed(cmd: &str) -> bool {
             | "project_rename"
             | "light_edit_open"
             | "workspace_create"
+            | "workspace_discover_projects"
             | "workspace_update"
             | "workspace_attach"
             | "cancel_request"

crates/ide-host/tests/mcp.rs

@@ -0,0 +1,418 @@
+use ide_core::{CancellationToken, ChangeSet, Diagnostic, IdeEvent, Pos, Range, Severity, TextChange};
+use ide_host::mcp::{FileProblems, FocusedEditor, Registry};
+use ide_host::{Host, HostConfig};
+use ide_mcp::ToolRegistry;
+use serde_json::{Value, json};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+struct Harness {
+    host: Arc<Host>,
+    root: PathBuf,
+    tmp: tempfile::TempDir,
+    events: Arc<std::sync::Mutex<Vec<IdeEvent>>>,
+}
+impl Harness {
+    fn new() -> Self {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = dunce::canonicalize(tmp.path()).unwrap().join("project");
+        std::fs::create_dir_all(root.join("src")).unwrap();
+        std::fs::write(root.join("src/a.txt"), "old text\nneedle needle\n").unwrap();
+        std::fs::write(root.join("src/b.txt"), "needle\n").unwrap();
+        std::fs::create_dir_all(root.join("ignored")).unwrap();
+        std::fs::write(root.join("ignored/a.txt"), "needle\n").unwrap();
+        std::fs::write(root.join(".gitignore"), "ignored/\n").unwrap();
+        let events = Arc::new(std::sync::Mutex::new(Vec::new()));
+        let sink = events.clone();
+        let host = Arc::new(Host::new(HostConfig {
+            config_dir: tmp.path().join("config"),
+            data_dir: tmp.path().join("data"),
+            local_data_dir: tmp.path().join("local"),
+            languages: Arc::new(ide_language::LanguageRegistry::load(None).unwrap()),
+            syntax: Arc::default(),
+            sink_for: Box::new(move |_| {
+                let events = sink.clone();
+                Arc::new(move |e| events.lock().unwrap().push(e))
+            }),
+            owner: |w| w,
+            runtime: tokio::runtime::Handle::current(),
+            project_environment: false,
+        }));
+        host.open_project("main", &root).unwrap();
+        Self { host, root, tmp, events }
+    }
+    async fn trust(&self) {
+        self.host.set_project_trust(&self.root, true, false).await.unwrap();
+    }
+    async fn error(&self, name: &str, args: Value) -> String {
+        let (host, root, name) = (self.host.clone(), self.root.clone(), name.to_owned());
+        let e = tokio::task::spawn_blocking(move || {
+            Registry::new(host).call(&root, &name, &args.to_string(), CancellationToken::new())
+        })
+        .await
+        .unwrap()
+        .unwrap_err();
+        match e {
+            ide_mcp::ToolCallError::Failed(e) | ide_mcp::ToolCallError::UnknownTool(e) => e,
+        }
+    }
+    async fn request(&self) -> u32 {
+        tokio::time::timeout(std::time::Duration::from_secs(10), async {
+            loop {
+                if let Some(id) = self.events.lock().unwrap().iter().rev().find_map(|e| match e {
+                    IdeEvent::McpRequest { id, .. } => Some(*id),
+                    _ => None,
+                }) {
+                    return id;
+                }
+                tokio::time::sleep(std::time::Duration::from_millis(10)).await;
+            }
+        })
+        .await
+        .unwrap()
+    }
+    async fn call(&self, name: &str, args: Value) -> String {
+        let (host, root, name) = (self.host.clone(), self.root.clone(), name.to_owned());
+        tokio::task::spawn_blocking(move || {
+            Registry::new(host).call(&root, &name, &args.to_string(), CancellationToken::new())
+        })
+        .await
+        .unwrap()
+        .unwrap()
+    }
+    async fn json(&self, name: &str, args: Value) -> Value {
+        serde_json::from_str(&self.call(name, args).await).unwrap()
+    }
+}
+impl Drop for Harness {
+    fn drop(&mut self) {
+        self.host.close_project("main");
+        self.host.close_project("second");
+    }
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn reads_unsaved_text_and_searches_the_overlay_with_a_limit() {
+    let h = Harness::new();
+    let p = h.host.project("main").unwrap();
+    let doc = p.documents.open(&h.root.join("src/a.txt")).unwrap();
+    p.documents
+        .edit(
+            doc.id,
+            doc.version,
+            ChangeSet { changes: vec![TextChange { from: 0, to: 3, insert: "fresh needle".into() }] },
+        )
+        .unwrap();
+    assert_eq!(
+        h.call("read_file", json!({"file_path":"src/a.txt","offset":1,"limit":5})).await,
+        "L1: fresh needle text\nL2: needle needle\nL3: "
+    );
+    let found = h.json("search_text", json!({"q":"needle","limit":2})).await;
+    assert_eq!(found["items"].as_array().unwrap().len(), 2);
+    assert_eq!(found["more"], true);
+    let all = h.json("search_text", json!({"q":"fresh","limit":20})).await;
+    assert_eq!(all["items"][0]["filePath"], "src/a.txt");
+    let all = h.json("search_text", json!({"q":"needle","limit":20})).await;
+    assert!(all["items"].as_array().unwrap().iter().all(|v| !v["filePath"].as_str().unwrap().contains("ignored")));
+    let files = h.json("search_file", json!({"q":"*.txt","paths":["src/**"]})).await;
+    assert_eq!(files["items"], json!([{"filePath":"src/a.txt"},{"filePath":"src/b.txt"}]));
+    let regex = h.json("search_regex", json!({"q":"fresh\\s+needle"})).await;
+    assert_eq!(regex["items"][0]["startColumn"], 1);
+    assert_eq!(std::fs::read_to_string(h.root.join("src/a.txt")).unwrap(), "old text\nneedle needle\n");
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn window_reports_supply_editor_selection_and_problems_then_disappear_on_close() {
+    let h = Harness::new();
+    let path = h.root.join("src/a.txt");
+    h.host.mcp_reports.set_open_editors("main", vec![path.clone()]);
+    h.host.mcp_reports.set_focused_editor(
+        "main",
+        Some(FocusedEditor {
+            path: path.clone().into(),
+            selection: Range::new(Pos::new(1, 2), Pos::new(1, 4)),
+            selected_text: "ed".into(),
+        }),
+        true,
+    );
+    let d = Diagnostic {
+        range: Range::point(Pos::new(1, 2)),
+        severity: Severity::Warning,
+        message: "reported warning".into(),
+        source: Some("inspection".into()),
+        code: None,
+        unnecessary: false,
+        deprecated: false,
+        server: None,
+    };
+    h.host.mcp_reports.report_problems("main", true, vec![FileProblems { path: path.clone().into(), items: vec![d] }]);
+    assert_eq!(h.json("get_all_open_file_paths", json!({})).await["openFiles"], json!(["src/a.txt"]));
+    let focused = h.json("get_current_file", json!({})).await;
+    assert_eq!(focused["selectedText"], "ed");
+    assert_eq!(focused["selection"]["startColumn"], 3);
+    let problems = h.json("get_file_problems", json!({"filePath":"src/a.txt","errorsOnly":false})).await;
+    assert_eq!(problems["errors"][0]["description"], "reported warning");
+    assert_eq!(h.json("get_project_problems", json!({})).await["files"].as_array().unwrap().len(), 1);
+    h.host.close_project("main");
+    h.host.open_project("main", &h.root).unwrap();
+    assert_eq!(h.json("get_all_open_file_paths", json!({})).await["openFiles"], json!([]));
+    assert_eq!(h.json("get_current_file", json!({})).await, json!({}));
+    assert_eq!(h.json("get_project_problems", json!({})).await["files"], json!([]));
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn restricted_projects_have_only_read_tools_and_remote_projects_explain_the_limitation() {
+    let h = Harness::new();
+    assert!(!h.host.project("main").unwrap().is_trusted());
+    let registry = Registry::new(h.host.clone());
+    assert!(registry.tools(&h.root).unwrap().iter().all(|t| t.read_only && !t.destructive));
+    assert!(!h.host.global_settings.effective().mcp_server.enabled);
+    h.host.mcp_reports.set_remote("remote", PathBuf::from("/remote/project"));
+    assert_eq!(registry.tools(Path::new("/remote/project")).unwrap_err(), "not supported for remote projects yet");
+    h.host.close_project_detached("remote");
+    assert!(!registry.projects().contains(&PathBuf::from("/remote/project")));
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn project_path_argument_routes_to_another_open_project() {
+    let h = Harness::new();
+    let second = h.tmp.path().join("second");
+    std::fs::create_dir_all(second.join("nested")).unwrap();
+    std::fs::write(second.join("unique.txt"), "second project").unwrap();
+    h.host.open_project("second", &second).unwrap();
+    let discovery = ide_mcp::discovery_path(h.tmp.path());
+    let _server = ide_mcp::McpServer::start(
+        Arc::new(Registry::new(h.host.clone())),
+        Some(discovery.clone()),
+        &tokio::runtime::Handle::current(),
+    )
+    .unwrap();
+    let request = json!({"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"read_file","arguments":{
+        "projectPath":second.join("nested"),"file_path":"unique.txt"}}});
+    let input = format!("{request}\n");
+    let mut output = Vec::new();
+    ide_mcp::stdio::bridge(&discovery, &h.root, input.as_bytes(), &mut output).await.unwrap();
+    let reply: Value = serde_json::from_slice(&output).unwrap();
+    assert_eq!(reply["result"]["content"][0]["text"], "L1: second project");
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn mutations_preserve_unsaved_text_and_reject_metadata_and_escapes() {
+    let h = Harness::new();
+    h.trust().await;
+    let p = h.host.project("main").unwrap();
+    let path = h.root.join("src/a.txt");
+    let doc = p.documents.open(&path).unwrap();
+    p.documents
+        .edit(doc.id, doc.version, ChangeSet { changes: vec![TextChange { from: 0, to: 3, insert: "unsaved".into() }] })
+        .unwrap();
+    let output = h.call("apply_patch", json!({"input":"*** Begin Patch\n*** Update File: src/a.txt\n@@\n-unsaved text\n+agent text\n*** End Patch"})).await;
+    assert!(output.starts_with("1 out of 1"), "{output}");
+    assert_eq!(p.documents.text_snapshot(doc.id).unwrap().text, "agent text\nneedle needle\n");
+    assert!(p.documents.is_dirty(doc.id).unwrap());
+    assert_eq!(std::fs::read_to_string(&path).unwrap(), "old text\nneedle needle\n");
+    assert!(
+        h.events.lock().unwrap().iter().any(|e| matches!(e, IdeEvent::DocPatched { doc: id, .. } if *id == doc.id))
+    );
+    let edit_id = h
+        .events
+        .lock()
+        .unwrap()
+        .iter()
+        .rev()
+        .find_map(|event| match event {
+            IdeEvent::WorkspaceEditApplied { id, .. } => Some(*id),
+            _ => None,
+        })
+        .unwrap();
+    p.documents.undo_workspace_edit(edit_id).unwrap();
+    assert_eq!(p.documents.text_snapshot(doc.id).unwrap().text, "unsaved text\nneedle needle\n");
+    p.documents.redo_workspace_edit(edit_id).unwrap();
+    assert_eq!(p.documents.text_snapshot(doc.id).unwrap().text, "agent text\nneedle needle\n");
+    h.call("create_new_file", json!({"pathInProject":"new/deep.txt","text":"hello\r\n"})).await;
+    // A new file gets the platform's default line separator.
+    let expected = if cfg!(windows) { "hello\r\n" } else { "hello\n" };
+    assert_eq!(std::fs::read_to_string(h.root.join("new/deep.txt")).unwrap(), expected);
+    h.call("create_new_file", json!({"pathInProject":"src/a.txt","text":"buffer only","overwrite":true})).await;
+    assert_eq!(p.documents.text_snapshot(doc.id).unwrap().text, "buffer only");
+    assert_eq!(std::fs::read_to_string(&path).unwrap(), "old text\nneedle needle\n");
+    for path in [".git/config", "nested/.git/HEAD", "../escape.txt"] {
+        let e = h.error("create_new_file", json!({"pathInProject":path,"text":"no"})).await;
+        assert!(e.contains("VCS metadata") || e.contains("outside"), "{path}: {e}");
+    }
+    #[cfg(unix)]
+    {
+        std::os::unix::fs::symlink(h.tmp.path(), h.root.join("escape")).unwrap();
+        assert!(h.error("create_new_file", json!({"pathInProject":"escape/outside.txt"})).await.contains("outside"));
+    }
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn execution_requires_a_window_and_denial_never_runs_a_build() {
+    let h = Harness::new();
+    h.trust().await;
+    assert!(h.error("build_project", json!({})).await.contains("no project window"));
+    h.host.mcp_requests.set_ready("main", true);
+    let denied = h.error("build_project", json!({}));
+    let answer = async {
+        let id = h.request().await;
+        assert!(h.host.mcp_requests.answer("other", id, true, None).is_err());
+        h.host.mcp_requests.answer("main", id, false, None).unwrap();
+    };
+    let (error, ()) = tokio::join!(denied, answer);
+    assert!(error.contains("denied by the user"), "{error}");
+    assert!(h.host.processes.list().is_empty());
+    assert!(h.events.lock().unwrap().iter().any(|e| matches!(e, IdeEvent::McpRequestClosed { .. })));
+    h.events.lock().unwrap().clear();
+    let closed = h.error("build_project", json!({}));
+    let close = async {
+        h.request().await;
+        h.host.mcp_requests.forget_window("main");
+    };
+    let (error, ()) = tokio::join!(closed, close);
+    assert!(error.contains("window closed"), "{error}");
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn git_status_and_diff_on_a_temporary_repository() {
+    let h = Harness::new();
+    let git = |args: &[&str]| {
+        let output = std::process::Command::new("git").current_dir(&h.root).args(args).output().unwrap();
+        assert!(output.status.success(), "{}", String::from_utf8_lossy(&output.stderr));
+    };
+    git(&["init"]);
+    git(&["add", "."]);
+    git(&["-c", "user.name=Test", "-c", "[email protected]", "commit", "-m", "Initial"]);
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        let helper = h.tmp.path().join("fsmonitor");
+        std::fs::write(&helper, format!("#!/bin/sh\ntouch '{}'\n", h.tmp.path().join("executed").display())).unwrap();
+        std::fs::set_permissions(&helper, std::fs::Permissions::from_mode(0o755)).unwrap();
+        git(&["config", "core.fsmonitor", helper.to_str().unwrap()]);
+    }
+    std::fs::write(h.root.join("src/a.txt"), "changed\n").unwrap();
+    let status = h.json("git_status", json!({"repositoryPathRelativeToProject":"."})).await;
+    assert_eq!(status["repositories"][0]["unstagedCount"], 1);
+    assert!(h.call("git_diff", json!({"filePath":"src/a.txt"})).await.contains("+changed"));
+    assert!(h.call("git_diff", json!({})).await.contains("src/a.txt"));
+    assert!(h.call("git_diff", json!({"staged":true})).await.is_empty());
+    assert!(!h.tmp.path().join("executed").exists());
+}
+
+#[cfg(unix)]
+#[tokio::test(flavor = "multi_thread")]
+async fn reformat_uses_the_formatter_chain_and_preserves_a_dirty_buffer() {
+    use std::os::unix::fs::PermissionsExt;
+    let h = Harness::new();
+    h.trust().await;
+    std::fs::create_dir_all(h.root.join("vendor/bin")).unwrap();
+    std::fs::write(h.root.join("vendor/bin/php-cs-fixer"), "").unwrap();
+    std::fs::write(h.root.join(".php-cs-fixer.dist.php"), "<?php").unwrap();
+    let php = h.root.join("fake-php");
+    std::fs::write(&php, "#!/bin/sh\nfor last; do :; done\nsed 's/  echo/    echo/' \"$last\" > \"$last.new\" && mv \"$last.new\" \"$last\"\n").unwrap();
+    std::fs::set_permissions(&php, std::fs::Permissions::from_mode(0o755)).unwrap();
+    let p = h.host.project("main").unwrap();
+    p.settings.set(ide_workspace::SettingsScope::Project, "languages.php.interpreter", json!(php)).unwrap();
+    let path = h.root.join("src/Example.php");
+    std::fs::write(&path, "<?php\n  echo 1;\n").unwrap();
+    let doc = p.documents.open(&path).unwrap();
+    p.documents
+        .edit(doc.id, doc.version, ChangeSet { changes: vec![TextChange { from: 13, to: 14, insert: "2".into() }] })
+        .unwrap();
+    let before = p.documents.text_snapshot(doc.id).unwrap().text;
+    let diff = h.call("reformat_file", json!({"files":["src/Example.php"]})).await;
+    assert!(diff.contains("+    echo"), "{diff}");
+    assert_eq!(p.documents.text_snapshot(doc.id).unwrap().text, before.replace("  echo", "    echo"));
+    assert_eq!(std::fs::read_to_string(path).unwrap(), "<?php\n  echo 1;\n");
+    assert!(p.documents.is_dirty(doc.id).unwrap());
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn execute_reports_output_exit_code_and_requires_confirmation() {
+    let h = Harness::new();
+    h.trust().await;
+    let config = ide_run::RunConfig {
+        id: "test".into(),
+        name: "MCP test".into(),
+        kind: "shell".into(),
+        command: if cfg!(windows) { "echo captured-output& exit 7" } else { "echo captured-output; exit 7" }.into(),
+        args: vec![],
+        cwd: None,
+        env: Default::default(),
+        detected: false,
+        is_test: false,
+        debug_adapter: None,
+        allow_parallel: false,
+        extras: Default::default(),
+    };
+    ide_run::save_user_configs(&h.root, &[config]).unwrap();
+    assert!(
+        h.error("execute_run_configuration", json!({"configurationName":"MCP test"}))
+            .await
+            .contains("no project window")
+    );
+    h.host.mcp_requests.set_ready("main", true);
+    let denied = h.error("execute_run_configuration", json!({"configurationName":"MCP test"}));
+    let deny = async {
+        let id = h.request().await;
+        h.host.mcp_requests.answer("main", id, false, None).unwrap();
+    };
+    let (error, ()) = tokio::join!(denied, deny);
+    assert!(error.contains("denied by the user"));
+    assert!(h.host.processes.list().is_empty());
+    h.events.lock().unwrap().clear();
+    let run = h.json("execute_run_configuration", json!({"configurationName":"MCP test","timeout":10000}));
+    let allow = async {
+        let id = h.request().await;
+        h.host.mcp_requests.answer("main", id, true, None).unwrap();
+    };
+    let (result, ()) = tokio::join!(run, allow);
+    assert_eq!(result["exitCode"], 7);
+    assert!(result["output"].as_str().unwrap().contains("captured-output"));
+}
+
+#[tokio::test(flavor = "multi_thread")]
+#[ignore = "requires rust-analyzer, like language_smoke::rust"]
+async fn rust_references_and_rename_through_mcp() {
+    let h = Harness::new();
+    h.trust().await;
+    let fixture = Path::new(env!("CARGO_MANIFEST_DIR")).join("../../fixtures/rust-app");
+    for name in ["Cargo.toml", "Cargo.lock"] {
+        std::fs::copy(fixture.join(name), h.root.join(name)).unwrap();
+    }
+    for name in ["lib.rs", "main.rs", "parser.rs"] {
+        std::fs::copy(fixture.join("src").join(name), h.root.join("src").join(name)).unwrap();
+    }
+    let project = h.host.project("main").unwrap();
+    let doc = project.documents.open(&h.root.join("src/lib.rs")).unwrap();
+    let text = project.documents.text_snapshot(doc.id).unwrap().text;
+    let (line, row) = text.lines().enumerate().find(|(_, row)| row.contains("fn format_price")).unwrap();
+    let column = row[..row.find("format_price").unwrap()].encode_utf16().count() + 1;
+    let args = json!({"filePath":"src/lib.rs", "line":line + 1, "column":column});
+    let deadline = std::time::Instant::now() + std::time::Duration::from_secs(120);
+    loop {
+        let result = tokio::task::spawn_blocking({
+            let host = h.host.clone();
+            let root = h.root.clone();
+            let args = args.to_string();
+            move || Registry::new(host).call(&root, "find_references", &args, CancellationToken::new())
+        })
+        .await
+        .unwrap();
+        if let Ok(result) = result {
+            let refs: Value = serde_json::from_str(&result).unwrap();
+            if refs["locations"].as_array().is_some_and(|locations| {
+                locations.iter().any(|l| l["path"].as_str().is_some_and(|p| p.ends_with("main.rs")))
+            }) {
+                break;
+            }
+        }
+        assert!(std::time::Instant::now() < deadline, "language server did not find format_price references");
+        tokio::time::sleep(std::time::Duration::from_millis(500)).await;
+    }
+    let result = h.json("rename_refactoring", json!({"pathInProject":"src/lib.rs", "symbolName":"format_price", "newName":"format_amount", "line":line + 1, "column":column})).await;
+    assert_eq!(result["applied"], true, "{result}");
+    assert!(project.documents.text_snapshot(doc.id).unwrap().text.contains("format_amount"));
+    assert!(std::fs::read_to_string(h.root.join("src/main.rs")).unwrap().contains("format_amount"));
+}

crates/ide-host/tests/trust.rs

@@ -32,7 +32,10 @@ async fn application_commands_work_in_restricted_projects_and_without_a_project(
     assert!(!host.open_project("main", &root).unwrap().is_trusted());
     for command in [
         "app_info",
+        "workspace_discover_projects",
         "app_build_info",
+        "app_cli_install",
+        "app_cli_uninstall",
         "app_log_location",
         "app_check_update",
         "app_startup_update_check",

crates/ide-host/tests/vcs_worktrees.rs

@@ -91,3 +91,109 @@ async fn watcher_picks_up_a_worktree_added_below_the_project() {
     let roots = f.project.repos().roots();
     assert!(roots.contains(&linked), "watcher did not discover the worktree added below the project: {roots:?}");
 }
+
+impl Fixture {
+    async fn open(&self, root: &std::path::Path) {
+        self.host.trust.decide(root, true, false).unwrap();
+        let project = self.host.open_project("main", root).unwrap();
+        wait_for_repos(&project, 1).await;
+    }
+
+    fn linked(&self, path: &std::path::Path, branch: &str) {
+        git(&self.root, &["worktree", "add", "-b", branch, path.to_str().unwrap()]);
+    }
+
+    async fn assert_protected(&self, path: &std::path::Path) {
+        for force in [false, true] {
+            let error =
+                vcs::vcs_remove_worktree(&self.host, "main", None, path.to_path_buf(), force).await.unwrap_err();
+            assert_eq!(error.message, "Cannot remove a worktree containing the open project.");
+            assert!(path.join("file.txt").exists());
+        }
+    }
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn cannot_remove_the_open_linked_worktree_or_its_ancestor() {
+    let f = Fixture::new().await;
+    let linked = f.root.with_file_name("front");
+    f.linked(&linked, "front");
+    let nested = linked.join("src");
+    std::fs::create_dir(&nested).unwrap();
+    std::fs::write(linked.join("file.txt"), "uncommitted changes\n").unwrap();
+    for root in [&linked, &nested] {
+        f.open(root).await;
+        f.assert_protected(&linked).await;
+        assert_eq!(std::fs::read_to_string(linked.join("file.txt")).unwrap(), "uncommitted changes\n");
+        // Relative paths must be judged from the same repository as git uses.
+        let error = vcs::vcs_remove_worktree(&f.host, "main", None, ".".into(), true).await.unwrap_err();
+        assert_eq!(error.message, "Cannot remove a worktree containing the open project.");
+    }
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn sibling_with_a_shared_prefix_and_worktrees_below_the_project_stay_removable() {
+    for force in [false, true] {
+        let f = Fixture::new().await;
+        let linked = f.root.with_file_name("front");
+        let sibling = f.root.with_file_name("front-wt");
+        f.linked(&linked, "front");
+        f.linked(&sibling, "sibling");
+        f.open(&sibling).await;
+        vcs::vcs_remove_worktree(&f.host, "main", None, linked.clone(), force).await.unwrap();
+        assert!(!linked.exists());
+        assert!(sibling.exists());
+
+        let below = sibling.join("below");
+        f.linked(&below, "below");
+        vcs::vcs_remove_worktree(&f.host, "main", Some(sibling.clone()), below.clone(), force).await.unwrap();
+        assert!(!below.exists());
+
+        let parent = f.root.parent().unwrap();
+        f.open(parent).await;
+        vcs::vcs_remove_worktree(&f.host, "main", Some(f.root.clone()), sibling.clone(), force).await.unwrap();
+        assert!(!sibling.exists());
+    }
+}
+
+#[cfg(unix)]
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn symlinked_project_root_is_protected() {
+    let f = Fixture::new().await;
+    let linked = f.root.with_file_name("front");
+    f.linked(&linked, "front");
+    let alias = f.root.with_file_name("alias");
+    std::os::unix::fs::symlink(&linked, &alias).unwrap();
+    f.open(&alias).await;
+    f.assert_protected(&linked).await;
+    f.assert_protected(&alias).await;
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn missing_project_and_worktree_paths_still_use_canonical_ancestors() {
+    let f = Fixture::new().await;
+    let linked = f.root.with_file_name("front");
+    f.linked(&linked, "front");
+    let nested = linked.join("src");
+    std::fs::create_dir(&nested).unwrap();
+    f.open(&nested).await;
+    std::fs::remove_dir(&nested).unwrap();
+    f.assert_protected(&linked).await;
+    std::fs::remove_dir_all(&linked).unwrap();
+    for force in [false, true] {
+        let error =
+            vcs::vcs_remove_worktree(&f.host, "main", Some(f.root.clone()), linked.clone(), force).await.unwrap_err();
+        assert_eq!(error.message, "Cannot remove a worktree containing the open project.");
+    }
+}
+
+#[cfg(target_os = "macos")]
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn tmp_alias_is_protected() {
+    let f = Fixture::new().await;
+    let linked = f.root.with_file_name("front");
+    f.linked(&linked, "front");
+    f.open(&linked).await;
+    let alias = std::path::Path::new("/").join(linked.strip_prefix("/private").unwrap());
+    f.assert_protected(&alias).await;
+}

crates/ide-language/queries/kotlin/highlights.scm

@@ -0,0 +1,21 @@
+(class_declaration name: (identifier) @type)
+(object_declaration name: (identifier) @type)
+(companion_object name: (identifier) @type)
+(type_alias type: (identifier) @type)
+(user_type (identifier) @type)
+(type_parameter (identifier) @type)
+(function_declaration name: (identifier) @function.definition)
+(parameter (identifier) @parameter.kotlin)
+(class_parameter (identifier) @parameter.kotlin ":")
+(property_declaration (variable_declaration (identifier) @variable))
+(class_body (property_declaration (variable_declaration (identifier) @property)))
+(class_parameter ["val" "var"] (identifier) @property ":")
+(enum_entry (identifier) @constant)
+(annotation (user_type (identifier) @attribute))
+(annotation (constructor_invocation (user_type (identifier) @attribute)))
+(call_expression . (identifier) @function)
+(call_expression . (navigation_expression (identifier) @function .))
+(class_modifier) @keyword
+(block_comment) @comment
+((block_comment) @comment.documentation (#match? @comment.documentation "^/\\*\\*"))
+(escape_sequence) @string.escape

crates/ide-language/src/registry.rs

@@ -692,6 +692,27 @@ mod tests {
         }
     }
 
+    #[test]
+    fn laravel_lsp_serves_php_files_only_below_artisan() {
+        let reg = reg();
+        let cfg = reg.get(&LanguageId::new("php")).unwrap();
+        let names: Vec<&str> = cfg.language_servers.iter().map(|s| s.name.as_str()).collect();
+        // After the fallback: hover, rename and symbols stay with Intelephense.
+        assert_eq!(names, ["intelephense", "phpactor", "laravel-lsp"]);
+        let lsp = cfg.language_servers.iter().find(|s| s.name == "laravel-lsp").unwrap();
+        assert_eq!(lsp.command.as_str(), "laravel-lsp");
+        assert!(lsp.require_root_marker && !lsp.fallback);
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        for dir in ["shop", "lib"] {
+            std::fs::create_dir_all(root.join(dir)).unwrap();
+        }
+        std::fs::write(root.join("shop/artisan"), "").unwrap();
+        let served = |file: &str| crate::marked_root(Some(root), &root.join(file), &lsp.root_markers);
+        assert_eq!(served("shop/app/Models/Order.php"), Some(root.join("shop")));
+        assert_eq!(served("lib/src/Parser.php"), None);
+    }
+
     #[test]
     fn ruff_serves_python_files_only_below_its_config() {
         let reg = reg();
@@ -963,6 +984,20 @@ mod tests {
         assert_eq!(res.line_comment.as_deref(), Some(";"));
     }
 
+    #[test]
+    fn go_enables_semantic_tokens_when_the_server_initializes() {
+        let reg = reg();
+        let go = reg.get(&LanguageId::new("go")).unwrap();
+        assert_eq!(
+            go.language_servers[0]
+                .initialization_options
+                .as_ref()
+                .and_then(|options| options.get("semanticTokens"))
+                .and_then(toml::Value::as_bool),
+            Some(true)
+        );
+    }
+
     #[test]
     fn astro_server_reads_the_project_typescript() {
         let reg = reg();

crates/ide-language/src/syntax/grammars.rs

@@ -120,7 +120,7 @@ pub(crate) static SPECS: &[Spec] = &[
         name: "kotlin",
         language: tree_sitter_kotlin_ng::LANGUAGE,
         outline: outline!("kotlin"),
-        highlights: None,
+        highlights: Some(Highlights { query: highlights!("kotlin"), first_wins: false }),
         fold_nodes: &["string_literal"],
         fold_bodies: NONE,
         imports: &["import"],

crates/ide-language/src/syntax/highlight.rs

@@ -42,11 +42,12 @@ pub enum SyntaxHighlightKind {
     Tag,
     Operator,
     Punctuation,
+    Parameter,
 }
 
 impl SyntaxHighlightKind {
     /// Every kind, in `as u32` order: the legend for [`SyntaxHighlights::data`].
-    pub const ALL: [Self; 24] = [
+    pub const ALL: [Self; 25] = [
         Self::Keyword,
         Self::String,
         Self::StringSpecial,
@@ -71,6 +72,7 @@ impl SyntaxHighlightKind {
         Self::Tag,
         Self::Operator,
         Self::Punctuation,
+        Self::Parameter,
     ];
 
     /// The kebab-case name plugins use (`doc-comment`, `function-call`, …).
@@ -162,6 +164,7 @@ const CAPTURES: &[(&str, Paint)] = {
         ("variable.member", Kind(K::Property)),
         ("variable.field", Kind(K::Property)),
         ("variable", Kind(K::Variable)),
+        ("parameter.kotlin", Kind(K::Parameter)),
         ("parameter", Kind(K::Variable)),
         ("property", Kind(K::Property)),
         ("field", Kind(K::Property)),
@@ -361,6 +364,9 @@ mod tests {
         assert_eq!(paint_for("string.special.path"), Some(Paint::Kind(K::StringSpecial)));
         assert_eq!(paint_for("comment.doc.__attribute__"), Some(Paint::Kind(K::DocComment)));
         assert_eq!(paint_for("punctuation.bracket"), Some(Paint::Kind(K::Punctuation)));
+        assert_eq!(paint_for("parameter.kotlin"), Some(Paint::Kind(K::Parameter)));
+        assert_eq!(paint_for("parameter"), Some(Paint::Kind(K::Variable)));
+        assert_eq!(paint_for("variable.parameter"), Some(Paint::Kind(K::Variable)));
         assert_eq!(paint_for("embedded"), Some(Paint::Clear));
         assert_eq!(paint_for("__name__"), None);
         assert_eq!(paint_for("spell"), None);
@@ -376,6 +382,59 @@ mod tests {
             .collect()
     }
 
+    #[test]
+    fn kotlin_supplements_stream_highlighting_with_declaration_roles() {
+        use SyntaxHighlightKind as K;
+        let src = "package palette\n/** Docs */\n@Deprecated(\"old\")\nclass Greeter(val name: String) {\n var count: Int = 0\n fun greet(prefix: String): String { val message = \"hello\\n\"; println(message); return prefix }\n}\ntypealias Handler = (String) -> Unit\nvalue class UserId(val value: String)\n";
+        let got = spans("kotlin", src);
+        for (text, expected) in [
+            ("Deprecated", K::Attribute),
+            ("Greeter", K::Type),
+            ("name", K::Property),
+            ("count", K::Property),
+            ("greet", K::Function),
+            ("prefix", K::Parameter),
+            ("message", K::Variable),
+            ("println", K::FunctionCall),
+            ("Handler", K::Type),
+            ("value", K::Keyword),
+            ("/** Docs */", K::DocComment),
+            ("\\n", K::Escape),
+        ] {
+            assert!(
+                got.iter().any(|(word, kind)| word == text && *kind == expected),
+                "missing {text}: {expected:?} in {got:?}"
+            );
+        }
+    }
+
+    #[test]
+    fn non_kotlin_parameters_keep_variable_highlighting() {
+        for (lang, src) in [
+            ("graphql", "query Hero { hero(id: 1) { name } }"),
+            ("gdscript", "func greet(id: int):\n\tpass\n"),
+            ("zig", "fn greet(id: u32) void {}"),
+            ("nix", "{ id }: id"),
+        ] {
+            let got = spans(lang, src);
+            assert!(
+                got.iter().any(|(text, kind)| text == "id" && *kind == SyntaxHighlightKind::Variable),
+                "{lang}: {got:?}"
+            );
+            assert!(!got.iter().any(|(_, kind)| *kind == SyntaxHighlightKind::Parameter), "{lang}: {got:?}");
+        }
+    }
+
+    #[test]
+    fn kotlin_constructor_defaults_are_not_declarations() {
+        let got = spans("kotlin", "class Example(val name: String = fallback, count: Int = defaultCount)");
+        assert!(got.iter().any(|(text, kind)| text == "name" && *kind == SyntaxHighlightKind::Property));
+        assert!(got.iter().any(|(text, kind)| text == "count" && *kind == SyntaxHighlightKind::Parameter));
+        for reference in ["fallback", "defaultCount"] {
+            assert!(!got.iter().any(|(text, _)| text == reference), "{got:?}");
+        }
+    }
+
     #[test]
     fn highlights_elixir() {
         use SyntaxHighlightKind as K;

crates/ide-lsp/src/jdtls.rs

@@ -351,6 +351,115 @@ pub fn compile_errors(
     (errors, count)
 }
 
+fn launch_path(path: &Path) -> PathBuf {
+    // Resolve existing ancestors too: diagnostics may name a file that was just deleted.
+    let resolved = path.ancestors().find_map(|ancestor| {
+        dunce::canonicalize(ancestor).ok().map(|root| root.join(path.strip_prefix(ancestor).unwrap()))
+    });
+    let mut path = resolved.as_deref().unwrap_or(path).to_string_lossy().replace('\\', "/");
+    if path.as_bytes().get(1) == Some(&b':') {
+        path[..1].make_ascii_lowercase();
+    }
+    PathBuf::from(path)
+}
+
+/// The runtime classpath identifies the launched module's dependencies: a directory
+/// filter alone either drops their errors or includes unrelated reactor modules.
+struct LaunchScope {
+    module: PathBuf,
+    /// None means the dependency scope could not be resolved; retain all errors.
+    roots: Option<Vec<PathBuf>>,
+    test: bool,
+}
+
+impl LaunchScope {
+    fn new(module: &Path, test: bool, cp: Option<&JavaClasspath>) -> Self {
+        let started = Instant::now();
+        let module = launch_path(module);
+        let roots = cp.and_then(|cp| {
+            let mut roots = vec![module.clone()];
+            let mut has_output = false;
+            let mut projects = std::collections::HashMap::<PathBuf, Option<PathBuf>>::new();
+            for entry in cp.class_paths.iter().chain(&cp.module_paths) {
+                let path = project_path(entry).unwrap_or_else(|| PathBuf::from(entry));
+                if path
+                    .extension()
+                    .is_some_and(|ext| ext.eq_ignore_ascii_case("jar") || ext.eq_ignore_ascii_case("zip"))
+                {
+                    continue;
+                }
+                let path = launch_path(&path);
+                let root = path
+                    .ancestors()
+                    .find_map(|ancestor| {
+                        let relative = path.strip_prefix(ancestor).ok()?;
+                        let output = match ancestor.file_name()?.to_str()? {
+                            "target" => relative == Path::new("classes") || relative == Path::new("test-classes"),
+                            "build" => relative.starts_with("classes") || relative.starts_with("resources"),
+                            _ => false,
+                        };
+                        output.then(|| ancestor.parent().map(Path::to_path_buf)).flatten()
+                    })
+                    .or_else(|| {
+                        let mut visited = Vec::new();
+                        let mut project = None;
+                        for ancestor in path.ancestors() {
+                            if let Some(cached) = projects.get(ancestor) {
+                                project = cached.clone();
+                                break;
+                            }
+                            visited.push(ancestor.to_path_buf());
+                            if ["pom.xml", "build.gradle", "build.gradle.kts", ".project"]
+                                .iter()
+                                .any(|name| ancestor.join(name).is_file())
+                            {
+                                project = Some(ancestor.to_path_buf());
+                                break;
+                            }
+                        }
+                        for ancestor in visited {
+                            projects.insert(ancestor, project.clone());
+                        }
+                        project
+                    })?;
+                has_output = true;
+                if !roots.contains(&root) {
+                    roots.push(root);
+                }
+            }
+            has_output.then_some(roots)
+        });
+        tracing::debug!(
+            elapsed_us = started.elapsed().as_micros(),
+            scoped = roots.is_some(),
+            "Java launch diagnostic scope"
+        );
+        Self { module, roots, test }
+    }
+
+    fn includes(&self, path: &Path) -> bool {
+        let Some(roots) = &self.roots else { return true };
+        let path = launch_path(path);
+        let Some(root) =
+            roots.iter().filter(|root| path.starts_with(root)).max_by_key(|root| root.components().count())
+        else {
+            return false;
+        };
+        let relative = path.strip_prefix(root).unwrap();
+        let parts: Vec<_> = relative.components().collect();
+        let test_source = parts.windows(2).any(|pair| pair[0].as_os_str() == "src" && pair[1].as_os_str() == "test");
+        !test_source || (self.test && *root == self.module)
+    }
+}
+
+/// JDTLS reports all imported projects; report errors for the launch and its dependencies.
+fn launch_compile_errors(
+    scope: &LaunchScope,
+    diagnostics: Vec<(PathBuf, lsp_types::Diagnostic)>,
+) -> (Vec<JavaCompileError>, u32) {
+    compile_errors(diagnostics.into_iter().filter(|(path, _)| scope.includes(path)).collect(), MAX_LAUNCH_ERRORS)
+}
+
 /// `java.project.getClasspaths` result.
 pub fn parse_classpaths(v: &Value) -> JavaClasspath {
     let strings = |key: &str| -> Vec<String> {
@@ -740,12 +849,6 @@ impl LspManager {
         if build == Some(JavaBuildStatus::Cancelled) {
             return Err(IdeError::cancelled());
         }
-        let (errors, error_count) = match build {
-            Some(JavaBuildStatus::WithErrors | JavaBuildStatus::Failed) => {
-                cancellable_wait(cancel, self.java_compile_errors(module)).await?
-            }
-            _ => (Vec::new(), 0),
-        };
         let (cp, java_home) = {
             let (server, _) = self.jdtls(module, cancel).await?;
             let _lock = if build_lock_held {
@@ -753,7 +856,15 @@ impl LspManager {
             } else {
                 Some(cancellable_wait(cancel, server.java_build_lock.lock()).await?)
             };
-            let cp = self.java_classpath(module, test, cancel).await?;
+            let cp = match self.java_classpath(module, test, cancel).await {
+                Ok(cp) => Some(cp),
+                Err(e) if e.kind == ErrorKind::Cancelled => return Err(e),
+                Err(e) if matches!(build, Some(JavaBuildStatus::WithErrors | JavaBuildStatus::Failed)) => {
+                    tracing::debug!("java.project.getClasspaths: {e}; retaining all compile errors");
+                    None
+                }
+                Err(e) => return Err(e),
+            };
             let java_home = match self.java_vm_location(module, cancel).await {
                 Ok(home) => home,
                 Err(e) if e.kind == ErrorKind::Cancelled => return Err(e),
@@ -764,6 +875,25 @@ impl LspManager {
             };
             (cp, java_home)
         };
+        let (errors, error_count, scoped) = match build {
+            Some(JavaBuildStatus::WithErrors | JavaBuildStatus::Failed) => {
+                let scope_module = module.to_path_buf();
+                let cp = cp.clone();
+                let scope = tokio::task::spawn_blocking(move || LaunchScope::new(&scope_module, test, cp.as_ref()))
+                    .await
+                    .map_err(|e| IdeError::internal(e.to_string()))?;
+                let scoped = scope.roots.is_some();
+                let (errors, count) = cancellable_wait(cancel, self.java_compile_errors(module, scope)).await??;
+                (errors, count, scoped)
+            }
+            _ => (Vec::new(), 0, false),
+        };
+        let build = if build == Some(JavaBuildStatus::WithErrors) && error_count == 0 && scoped {
+            Some(JavaBuildStatus::Succeeded)
+        } else {
+            build
+        };
+        let cp = cp.unwrap_or_default();
         Ok(JavaLaunchInfo {
             build,
             project_root: cp.project_root,
@@ -779,16 +909,20 @@ impl LspManager {
         })
     }
 
-    /// Compile errors jdtls reports for its workspace (all modules it imported).
-    async fn java_compile_errors(&self, module: &Path) -> (Vec<JavaCompileError>, u32) {
-        let Ok((server, _)) = self.jdtls(module, &CancellationToken::new()).await else { return (Vec::new(), 0) };
-        let collect = || compile_errors(server.diagnostics_snapshot(), MAX_LAUNCH_ERRORS);
-        let found = collect();
-        if found.1 > 0 {
-            return found;
-        }
-        let _ = tokio::time::timeout(ERRORS_WAIT, server.published_notify.notified()).await;
-        collect()
+    /// Wait for late build markers only when no error diagnostics have arrived yet.
+    async fn java_compile_errors(&self, module: &Path, scope: LaunchScope) -> IdeResult<(Vec<JavaCompileError>, u32)> {
+        let (server, _) = self.jdtls(module, &CancellationToken::new()).await?;
+        let diagnostics = server.diagnostics_snapshot();
+        let has_errors = diagnostics.iter().any(|(_, d)| d.severity == Some(lsp_types::DiagnosticSeverity::ERROR));
+        let diagnostics = if has_errors {
+            diagnostics
+        } else {
+            let _ = tokio::time::timeout(ERRORS_WAIT, server.published_notify.notified()).await;
+            server.diagnostics_snapshot()
+        };
+        tokio::task::spawn_blocking(move || launch_compile_errors(&scope, diagnostics))
+            .await
+            .map_err(|e| IdeError::internal(e.to_string()))
     }
 
     /// Resolve a disk/archive class to project source or the server's binary document.
@@ -1058,6 +1192,95 @@ mod tests {
         assert_eq!(count, 1);
     }
 
+    fn error_at(path: impl Into<PathBuf>) -> (PathBuf, lsp_types::Diagnostic) {
+        (
+            path.into(),
+            lsp_types::Diagnostic {
+                severity: Some(lsp_types::DiagnosticSeverity::ERROR),
+                message: "boom".into(),
+                ..Default::default()
+            },
+        )
+    }
+
+    #[test]
+    fn launch_errors_include_dependencies_but_only_the_launched_modules_tests() {
+        for output in ["target/classes", "build/classes/java/main", "build/classes/kotlin/main"] {
+            let cp = JavaClasspath {
+                class_paths: vec!["/p/web/target/classes".into(), format!("/p/service/{output}"), "/m2/lib.jar".into()],
+                module_paths: vec!["/p/api/target/classes".into()],
+                ..Default::default()
+            };
+            let paths = [
+                "/p/web/src/main/java/Main.java",
+                "/p/web/src/test/java/MainTest.java",
+                "/p/service/src/main/java/Service.java",
+                "/p/service/src/test/java/ServiceTest.java",
+                "/p/other/src/main/java/Other.java",
+                "/p/web-other/src/main/java/Other.java",
+                "/p/api/src/main/java/Api.java",
+                "/p/web/src/testing/Real.java",
+            ];
+            for (test, expected) in [(false, 4), (true, 5)] {
+                let scope = LaunchScope::new(Path::new("/p/web"), test, Some(&cp));
+                assert_eq!(launch_compile_errors(&scope, paths.iter().map(|p| error_at(*p)).collect()).1, expected);
+                assert!(scope.includes(Path::new("/p/service/src/main/java/Service.java")));
+                assert!(!scope.includes(Path::new("/p/service/src/test/java/ServiceTest.java")));
+            }
+        }
+    }
+
+    #[test]
+    fn unresolved_classpaths_retain_all_errors() {
+        for cp in [
+            None,
+            Some(JavaClasspath::default()),
+            Some(JavaClasspath { class_paths: vec!["/unknown/output".into()], ..Default::default() }),
+            Some(JavaClasspath { class_paths: vec!["/m2/lib.jar".into()], ..Default::default() }),
+            Some(JavaClasspath {
+                class_paths: vec!["/p/web/target/classes".into(), "/unknown/output".into()],
+                ..Default::default()
+            }),
+        ] {
+            let scope = LaunchScope::new(Path::new("/p/web"), false, cp.as_ref());
+            let diagnostics = ["/p/service/src/main/java/Service.java", "/p/other/src/test/java/Test.java"];
+            assert_eq!(launch_compile_errors(&scope, diagnostics.into_iter().map(error_at).collect()).1, 2);
+        }
+    }
+
+    #[test]
+    fn launch_scope_normalizes_windows_drive_letters_and_separators() {
+        let cp = JavaClasspath { class_paths: vec![r"C:\p\web\target\classes".into()], ..Default::default() };
+        let scope = LaunchScope::new(Path::new(r"c:\p\web"), false, Some(&cp));
+        assert!(scope.includes(Path::new("C:/p/web/src/main/java/Main.java")));
+        assert!(!scope.includes(Path::new(r"C:\p\web\src\test\java\MainTest.java")));
+        assert!(!scope.includes(Path::new("C:/p/web-other/src/main/java/Main.java")));
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn launch_scope_resolves_symlinks_and_project_reference_entries() {
+        let tmp = tempfile::tempdir().unwrap();
+        let module = tmp.path().join("web");
+        let dependency = tmp.path().join("service");
+        std::fs::create_dir_all(module.join("src/main/java")).unwrap();
+        std::fs::create_dir_all(&dependency).unwrap();
+        std::fs::write(dependency.join(".project"), "").unwrap();
+        let alias = tmp.path().join("alias");
+        std::os::unix::fs::symlink(&module, &alias).unwrap();
+        let cp = JavaClasspath {
+            class_paths: vec![
+                alias.join("target/classes").to_string_lossy().into_owned(),
+                crate::uri::path_to_uri_string(&dependency),
+            ],
+            ..Default::default()
+        };
+        let scope = LaunchScope::new(&alias, false, Some(&cp));
+        assert!(scope.includes(&dunce::canonicalize(&module).unwrap().join("src/main/java/Deleted.java")));
+        assert!(scope.includes(&dependency.join("src/main/java/Service.java")));
+        assert!(!scope.includes(&dependency.join("src/test/java/ServiceTest.java")));
+    }
+
     #[test]
     fn classpaths() {
         let v = json!({

crates/ide-lsp/tests/mock_server.rs

@@ -1821,6 +1821,59 @@ async fn java_launch_serializes_the_classpath_with_the_build_lock() {
     assert!(commands.contains(&"java.project.getClasspaths".to_owned()));
 }
 
+#[tokio::test(flavor = "multi_thread")]
+async fn java_launch_scopes_build_status_and_does_not_wait_for_unrelated_errors() {
+    use ide_lsp::jdtls::JavaBuildStatus;
+
+    let h = harness_for("java", "java", &[("jdtls", incremental_caps())], &[]);
+    h.open("Main.java", "class Main {}");
+    h.wait_status("jdtls", ServerStatus::Ready).await;
+    let state = h.launcher.state("jdtls");
+    state.respond("java/buildWorkspace", json!(2));
+    let web = h.root.join("web");
+    let classpath = json!({"classpaths": [web.join("target/classes"), h.root.join("service/target/classes")]});
+    for (path, test, expected, classpaths_available) in [
+        ("other/src/main/java/Other.java", false, JavaBuildStatus::Succeeded, true),
+        ("other/src/main/java/Other.java", false, JavaBuildStatus::Succeeded, true),
+        ("web/src/test/java/MainTest.java", false, JavaBuildStatus::Succeeded, true),
+        ("web/src/test/java/MainTest.java", true, JavaBuildStatus::WithErrors, true),
+        ("service/src/test/java/ServiceTest.java", true, JavaBuildStatus::Succeeded, true),
+        ("service/src/main/java/Service.java", false, JavaBuildStatus::WithErrors, true),
+        ("web/src/main/java/Main.java", false, JavaBuildStatus::WithErrors, true),
+        ("other/src/main/java/Other.java", false, JavaBuildStatus::WithErrors, false),
+    ] {
+        state.respond("workspace/executeCommand", classpath.clone());
+        if !classpaths_available {
+            state.errors.lock().insert("workspace/executeCommand".into(), (-32603, "classpath unavailable".into()));
+        }
+        let file = h.root.join(path);
+        std::fs::create_dir_all(file.parent().unwrap()).unwrap();
+        std::fs::write(&file, "broken").unwrap();
+        let diag = json!({"range": {"start":{"line":0,"character":0},"end":{"line":0,"character":1}},
+            "severity": 1, "message": path});
+        state
+            .peer()
+            .notify("textDocument/publishDiagnostics", json!({"uri": uri_of(&file), "diagnostics": [diag]}))
+            .unwrap();
+        eventually(|| diagnostics_for(&h, &file) == 1).await;
+        let info = tokio::time::timeout(
+            Duration::from_secs(1),
+            h.mgr.java_launch(&web, test, true, false, &Default::default()),
+        )
+        .await
+        .expect("an already-published error must not incur the diagnostics wait")
+        .unwrap();
+        assert_eq!(info.build, Some(expected), "{path}, test={test}, classpath={classpaths_available}");
+        assert_eq!(info.error_count, u32::from(expected == JavaBuildStatus::WithErrors));
+        state
+            .peer()
+            .notify("textDocument/publishDiagnostics", json!({"uri": uri_of(&file), "diagnostics": []}))
+            .unwrap();
+        eventually(|| diagnostics_for(&h, &file) == 2).await;
+        h.events.lock().clear();
+    }
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn open_java_files_are_checked_again_after_a_project_update() {
     let h = harness_for("java", "java", &[("jdtls", incremental_caps())], &[]);

crates/ide-mcp/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "ide-mcp"
+description = "The IDE's MCP server: Streamable HTTP on 127.0.0.1 for AI agents outside the IDE, its discovery file and the stdio bridge"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+bytes = "1"
+dunce.workspace = true
+getrandom = "0.3"
+http-body-util = "0.1"
+hyper = { version = "1", features = ["client", "http1", "server"] }
+hyper-util = { version = "0.1", default-features = false, features = ["tokio"] }
+percent-encoding = "2"
+serde.workspace = true
+serde_json.workspace = true
+tokio = { workspace = true, features = ["net", "io-std"] }
+tracing.workspace = true
+tokio-util.workspace = true
+
+[dev-dependencies]
+tempfile.workspace = true
+tokio = { workspace = true, features = ["net", "io-std", "rt-multi-thread", "macros"] }

crates/ide-mcp/src/discovery.rs

@@ -0,0 +1,94 @@
+//! `<app-data>/mcp/server.json`: where the running IDE's server listens and
+//! its token, for the stdio bridge. Readable only by the user; removed when
+//! the server stops.
+
+use serde::{Deserialize, Serialize};
+use std::io;
+use std::path::{Path, PathBuf};
+
+/// The discovery file, relative to the app data directory.
+pub const DISCOVERY_FILE: &str = "mcp/server.json";
+
+/// The discovery file of the IDE whose app data directory is `app_data`.
+pub fn discovery_path(app_data: &Path) -> PathBuf {
+    app_data.join(DISCOVERY_FILE)
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Discovery {
+    pub port: u16,
+    pub token: String,
+    /// The IDE's process.
+    pub pid: u32,
+    /// The IDE's version.
+    pub version: String,
+}
+
+impl Discovery {
+    pub fn read(path: &Path) -> io::Result<Self> {
+        let bytes = std::fs::read(path)?;
+        serde_json::from_slice(&bytes).map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))
+    }
+
+    /// Writes the file atomically, readable only by the user.
+    pub fn write(&self, path: &Path) -> io::Result<()> {
+        let dir = path.parent().ok_or_else(|| io::Error::other("no parent directory"))?;
+        std::fs::create_dir_all(dir)?;
+        let tmp = path.with_extension(format!("tmp{}", std::process::id()));
+        let bytes = serde_json::to_vec_pretty(self).map_err(io::Error::other)?;
+        let written = write_private(&tmp, &bytes).and_then(|()| std::fs::rename(&tmp, path));
+        if written.is_err() {
+            let _ = std::fs::remove_file(&tmp);
+        }
+        written
+    }
+
+    /// Removes the file at `path` if it still describes this process's server.
+    pub fn remove_if_ours(path: &Path) {
+        if Self::read(path).is_ok_and(|d| d.pid == std::process::id()) {
+            let _ = std::fs::remove_file(path);
+        }
+    }
+}
+
+#[cfg(unix)]
+fn write_private(path: &Path, bytes: &[u8]) -> io::Result<()> {
+    use std::io::Write;
+    use std::os::unix::fs::OpenOptionsExt;
+    let _ = std::fs::remove_file(path);
+    let mut file = std::fs::OpenOptions::new().write(true).create_new(true).mode(0o600).open(path)?;
+    file.write_all(bytes)?;
+    file.sync_all()
+}
+
+/// The app data directory is the user's own on Windows.
+#[cfg(not(unix))]
+fn write_private(path: &Path, bytes: &[u8]) -> io::Result<()> {
+    std::fs::write(path, bytes)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn round_trips_privately_and_only_its_owner_removes_it() {
+        let tmp = tempfile::tempdir().unwrap();
+        let path = discovery_path(tmp.path());
+        let ours = Discovery { port: 1234, token: "t".into(), pid: std::process::id(), version: "0.1.0".into() };
+        ours.write(&path).unwrap();
+        assert_eq!(Discovery::read(&path).unwrap(), ours);
+        #[cfg(unix)]
+        {
+            use std::os::unix::fs::PermissionsExt;
+            assert_eq!(std::fs::metadata(&path).unwrap().permissions().mode() & 0o777, 0o600);
+        }
+        let theirs = Discovery { pid: ours.pid.wrapping_add(1), ..ours.clone() };
+        theirs.write(&path).unwrap();
+        Discovery::remove_if_ours(&path);
+        assert!(path.is_file(), "another process's file stays");
+        ours.write(&path).unwrap();
+        Discovery::remove_if_ours(&path);
+        assert!(!path.exists());
+    }
+}

crates/ide-mcp/src/lib.rs

@@ -0,0 +1,154 @@
+//! The IDE's MCP server: AI agents outside the IDE (Claude Code, Codex…) call
+//! the IDE's built-in tools.
+//!
+//! - **Transport:** MCP Streamable HTTP (2025-06-18; 2025-03-26 and 2024-11-05
+//!   clients too) on `127.0.0.1:<random port>`, endpoint `/mcp`. Responses are
+//!   plain JSON (no SSE streams: `GET` is 405). Every request carries
+//!   `Authorization: Bearer <token>` (random, per run); requests from another
+//!   `Origin` or `Host` are refused (DNS rebinding).
+//! - **Projects:** the `X-OpenIDEA-Project` header or the `?project=` query
+//!   names a folder; the server picks the open project containing it.
+//! - **Discovery:** `<app-data>/mcp/server.json` (`port`, `token`, `pid`,
+//!   `version`; readable only by the user) while the server runs.
+//! - **Stdio:** `<app exe> --mcp-stdio [--project <path>]` reads the discovery
+//!   file and relays newline-delimited JSON-RPC to the server ([`stdio`]), so
+//!   persisted client configurations hold no token.
+//!
+//! The tools themselves come from a [`ToolRegistry`] (the IDE host); this
+//! crate knows nothing about plugins.
+
+mod discovery;
+mod protocol;
+mod server;
+pub mod stdio;
+
+pub use discovery::{DISCOVERY_FILE, Discovery, discovery_path};
+pub use server::McpServer;
+pub use tokio_util::sync::CancellationToken;
+
+use std::path::{Path, PathBuf};
+
+/// The header naming the project a request is about (an absolute path).
+pub const PROJECT_HEADER: &str = "x-openidea-project";
+/// The command-line flag that runs the executable as the stdio bridge.
+pub const STDIO_FLAG: &str = "--mcp-stdio";
+
+/// A tool as `tools/list` shows it.
+#[derive(Clone, Debug, PartialEq)]
+pub struct Tool {
+    pub name: String,
+    pub description: String,
+    /// A JSON Schema of the `arguments` object.
+    pub input_schema: serde_json::Value,
+    pub output_schema: Option<serde_json::Value>,
+    /// Only reads (`annotations.readOnlyHint`).
+    pub read_only: bool,
+    /// May destroy data (`annotations.destructiveHint`).
+    pub destructive: bool,
+}
+
+/// A failed `tools/call`.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum ToolCallError {
+    /// No such tool for the project: a protocol error.
+    UnknownTool(String),
+    /// The tool ran and failed, or couldn't run: a result with `isError`.
+    Failed(String),
+}
+
+/// Where the tools come from (the IDE host). Calls block; the server runs
+/// them off its async threads.
+pub trait ToolRegistry: Send + Sync + 'static {
+    /// Roots of the projects open in the IDE that the server serves.
+    fn projects(&self) -> Vec<PathBuf>;
+    /// The tools callable for `project` (one of [`Self::projects`]). `Err`
+    /// says why there are none (an unsupported project).
+    fn tools(&self, project: &Path) -> Result<Vec<Tool>, String>;
+    fn call_with_client(
+        &self,
+        project: &Path,
+        name: &str,
+        arguments: &str,
+        cancel: CancellationToken,
+        _client: &str,
+    ) -> Result<String, ToolCallError> {
+        self.call(project, name, arguments, cancel)
+    }
+
+    /// Runs tool `name` with `arguments` (a JSON object, as text) for `project`.
+    fn call(
+        &self,
+        project: &Path,
+        name: &str,
+        arguments: &str,
+        cancel: CancellationToken,
+    ) -> Result<String, ToolCallError>;
+}
+
+/// The URL of the server at `port` for `project`.
+pub fn endpoint_url(port: u16, project: &Path) -> String {
+    format!("http://127.0.0.1:{port}/mcp?project={}", encode_query(&project.to_string_lossy()))
+}
+
+/// The stdio bridge's command line for `project`: `exe --mcp-stdio --project <project>`.
+pub fn stdio_command(exe: &Path, project: &Path) -> Vec<String> {
+    vec![
+        exe.to_string_lossy().into_owned(),
+        STDIO_FLAG.to_owned(),
+        "--project".to_owned(),
+        project.to_string_lossy().into_owned(),
+    ]
+}
+
+/// Whether `args` (the process's, program name first) ask for the stdio
+/// bridge; then the project it is for (`--project <path>`, `None`: the
+/// current directory).
+pub fn stdio_request(args: &[String]) -> Option<Option<PathBuf>> {
+    let rest = args.get(1..).unwrap_or_default();
+    if !rest.iter().any(|a| a == STDIO_FLAG) {
+        return None;
+    }
+    let project = rest
+        .iter()
+        .position(|a| a == "--project")
+        .and_then(|i| rest.get(i + 1))
+        .map(PathBuf::from)
+        .or_else(|| rest.iter().find_map(|a| a.strip_prefix("--project=").map(PathBuf::from)));
+    Some(project)
+}
+
+/// Characters escaped in a query value: everything but unreserved characters and `/`.
+const QUERY: &percent_encoding::AsciiSet =
+    &percent_encoding::NON_ALPHANUMERIC.remove(b'-').remove(b'_').remove(b'.').remove(b'~').remove(b'/');
+
+pub(crate) fn encode_query(value: &str) -> String {
+    percent_encoding::utf8_percent_encode(value, QUERY).to_string()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn urls_and_commands_name_the_project() {
+        let url = endpoint_url(4321, Path::new("/home/me/my app/项目"));
+        assert_eq!(url, "http://127.0.0.1:4321/mcp?project=/home/me/my%20app/%E9%A1%B9%E7%9B%AE");
+        assert_eq!(
+            stdio_command(Path::new("/Applications/OpenIDEA.app/Contents/MacOS/openidea"), Path::new("/p")),
+            ["/Applications/OpenIDEA.app/Contents/MacOS/openidea", "--mcp-stdio", "--project", "/p"]
+        );
+    }
+
+    #[test]
+    fn stdio_requests_are_recognized() {
+        let args = |a: &[&str]| a.iter().map(|s| (*s).to_owned()).collect::<Vec<_>>();
+        assert_eq!(stdio_request(&args(&["openidea"])), None);
+        assert_eq!(stdio_request(&args(&["openidea", "/some/project"])), None);
+        assert_eq!(stdio_request(&args(&["openidea", "--mcp-stdio"])), Some(None));
+        assert_eq!(
+            stdio_request(&args(&["openidea", "--mcp-stdio", "--project", "/p"])),
+            Some(Some(PathBuf::from("/p")))
+        );
+        assert_eq!(stdio_request(&args(&["openidea", "--project=/q", "--mcp-stdio"])), Some(Some(PathBuf::from("/q"))));
+    }
+}

crates/ide-mcp/src/protocol.rs

@@ -0,0 +1,298 @@
+//! MCP over JSON-RPC 2.0: `initialize`, `ping`, `tools/list`, `tools/call`
+//! and notifications, for one POST body (a message or a batch). Blocking: the
+//! server runs it on a blocking thread.
+
+use crate::{CancellationToken, Tool, ToolCallError, ToolRegistry};
+use serde_json::{Value, json};
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+use std::sync::Mutex;
+
+#[derive(Default)]
+pub(crate) struct Requests(Mutex<RequestState>);
+#[derive(Default)]
+struct RequestState {
+    clients: HashMap<String, String>,
+    running: HashMap<(String, String), CancellationToken>,
+    early: HashMap<(String, String), std::time::Instant>,
+}
+struct InFlight<'a> {
+    requests: &'a Requests,
+    key: (String, String),
+}
+impl Drop for InFlight<'_> {
+    fn drop(&mut self) {
+        self.requests.0.lock().unwrap().running.remove(&self.key);
+    }
+}
+
+/// The protocol version answered when the client asks for one this server doesn't know.
+pub(crate) const LATEST: &str = "2025-06-18";
+pub(crate) const SUPPORTED: [&str; 3] = ["2025-06-18", "2025-03-26", "2024-11-05"];
+
+const PARSE_ERROR: i64 = -32700;
+const INVALID_REQUEST: i64 = -32600;
+const METHOD_NOT_FOUND: i64 = -32601;
+const INVALID_PARAMS: i64 = -32602;
+/// The requested folder isn't a project open in the IDE (or has no tools there).
+pub(crate) const NOT_OPEN: i64 = -32001;
+
+pub(crate) struct RpcError {
+    code: i64,
+    message: String,
+}
+
+impl RpcError {
+    fn new(code: i64, message: impl Into<String>) -> Self {
+        Self { code, message: message.into() }
+    }
+}
+
+pub(crate) fn error_response(id: Value, code: i64, message: &str) -> Value {
+    json!({ "jsonrpc": "2.0", "id": id, "error": { "code": code, "message": message } })
+}
+
+/// Answers one POST body: `Ok(None)` when it held only notifications and
+/// responses (HTTP 202), `Err` with the error response when it isn't JSON.
+pub(crate) fn handle_body(
+    registry: &dyn ToolRegistry,
+    project: Option<&str>,
+    body: &[u8],
+    requests: &Requests,
+    scope: &str,
+    cancel: CancellationToken,
+) -> Result<Option<Value>, Value> {
+    let message: Value = serde_json::from_slice(body)
+        .map_err(|e| error_response(Value::Null, PARSE_ERROR, &format!("not JSON: {e}")))?;
+    let session = Session { registry, project, requests, scope, cancel };
+    Ok(match message {
+        Value::Array(batch) if batch.is_empty() => Some(error_response(Value::Null, INVALID_REQUEST, "an empty batch")),
+        Value::Array(batch) => {
+            let replies: Vec<Value> = batch.into_iter().filter_map(|m| session.handle(m)).collect();
+            (!replies.is_empty()).then_some(Value::Array(replies))
+        }
+        message => session.handle(message),
+    })
+}
+
+struct Session<'a> {
+    registry: &'a dyn ToolRegistry,
+    project: Option<&'a str>,
+    requests: &'a Requests,
+    scope: &'a str,
+    cancel: CancellationToken,
+}
+
+impl Session<'_> {
+    /// The response to one message (`None` for notifications and responses).
+    fn handle(&self, message: Value) -> Option<Value> {
+        let Value::Object(mut message) = message else {
+            return Some(error_response(Value::Null, INVALID_REQUEST, "not a JSON-RPC message"));
+        };
+        let id = message.remove("id");
+        if message.get("jsonrpc") != Some(&json!("2.0"))
+            || id.as_ref().is_some_and(|id| !id.is_null() && !id.is_string() && !id.is_number())
+        {
+            return Some(error_response(Value::Null, INVALID_REQUEST, "invalid JSON-RPC envelope"));
+        }
+        let Some(method) = message.get("method").and_then(Value::as_str).map(str::to_owned) else {
+            // A response to a request of ours (we send none), or garbage.
+            return id.map(|id| error_response(id, INVALID_REQUEST, "not a JSON-RPC request"));
+        };
+        if method == "notifications/cancelled" {
+            if let Some(id) = message.get("params").and_then(|p| p.get("requestId")) {
+                let key = (self.scope.to_owned(), id.to_string());
+                let mut state = self.requests.0.lock().unwrap();
+                if let Some(cancel) = state.running.get(&key) {
+                    cancel.cancel();
+                } else if state.early.len() < 1024 {
+                    state.early.insert(key, std::time::Instant::now());
+                }
+            }
+            return None;
+        }
+        let id = id?;
+        let key = (self.scope.to_owned(), id.to_string());
+        let cancel = self.cancel.child_token();
+        {
+            let mut requests = self.requests.0.lock().unwrap();
+            requests.early.retain(|_, at| at.elapsed() < std::time::Duration::from_secs(60));
+            if requests.running.contains_key(&key) {
+                return Some(error_response(id, INVALID_REQUEST, "request id already in flight"));
+            }
+            if requests.early.remove(&key).is_some() {
+                cancel.cancel();
+            }
+            requests.running.insert(key.clone(), cancel.clone());
+        }
+        let _in_flight = InFlight { requests: self.requests, key };
+        let params = message.remove("params").unwrap_or(Value::Null);
+        let result = match self.request(&method, params, cancel) {
+            Ok(result) => json!({ "jsonrpc": "2.0", "id": id, "result": result }),
+            Err(e) => error_response(id, e.code, &e.message),
+        };
+        Some(result)
+    }
+
+    fn request(&self, method: &str, params: Value, cancel: CancellationToken) -> Result<Value, RpcError> {
+        match method {
+            "initialize" => Ok(self.initialize(&params)),
+            "ping" => Ok(json!({})),
+            "tools/list" => {
+                let project = self.project()?;
+                let tools = self.registry.tools(&project).map_err(|e| RpcError::new(NOT_OPEN, e))?;
+                Ok(json!({ "tools": tools.iter().map(tool_json).collect::<Vec<_>>() }))
+            }
+            "tools/call" => self.call(params, cancel),
+            _ => Err(RpcError::new(METHOD_NOT_FOUND, format!("no method {method:?}"))),
+        }
+    }
+
+    fn initialize(&self, params: &Value) -> Value {
+        if let Some(name) = params.pointer("/clientInfo/name").and_then(Value::as_str) {
+            let mut requests = self.requests.0.lock().unwrap();
+            if requests.clients.len() < 1024 {
+                requests.clients.insert(self.scope.into(), name.chars().take(128).collect());
+            }
+        }
+        let asked = params.get("protocolVersion").and_then(Value::as_str).unwrap_or(LATEST);
+        let version = if SUPPORTED.contains(&asked) { asked } else { LATEST };
+        let about = match self.project() {
+            Ok(root) => format!("the project open in OpenIDEA at {}", root.display()),
+            Err(_) => "a project open in OpenIDEA".to_owned(),
+        };
+        json!({
+            "protocolVersion": version,
+            "capabilities": { "tools": { "listChanged": false } },
+            "serverInfo": { "name": "OpenIDEA", "version": env!("CARGO_PKG_VERSION") },
+            "instructions": format!(
+                "Built-in OpenIDEA tools for {about}: they see the files and editors the IDE has open."
+            ),
+        })
+    }
+
+    fn call(&self, params: Value, cancel: CancellationToken) -> Result<Value, RpcError> {
+        let name = params
+            .get("name")
+            .and_then(Value::as_str)
+            .ok_or_else(|| RpcError::new(INVALID_PARAMS, "tools/call needs a tool `name`"))?;
+        let arguments = match params.get("arguments") {
+            None | Some(Value::Null) => "{}".to_owned(),
+            Some(args @ Value::Object(_)) => args.to_string(),
+            Some(_) => return Err(RpcError::new(INVALID_PARAMS, "`arguments` must be an object")),
+        };
+        let requested = params.pointer("/arguments/projectPath");
+        if requested.is_some_and(|v| !v.is_string()) {
+            return Err(RpcError::new(INVALID_PARAMS, "projectPath must be a string"));
+        }
+        let project = self.resolve_project(requested.and_then(Value::as_str).or(self.project))?;
+        let outcome = if cancel.is_cancelled() {
+            Err(ToolCallError::Failed("cancelled".into()))
+        } else {
+            let client =
+                self.requests.0.lock().unwrap().clients.get(self.scope).cloned().unwrap_or_else(|| "MCP client".into());
+            self.registry.call_with_client(&project, name, &arguments, cancel, &client)
+        };
+        let (text, is_error) = match outcome {
+            Ok(text) => (text, false),
+            Err(ToolCallError::Failed(message)) => (message, true),
+            Err(ToolCallError::UnknownTool(message)) => return Err(RpcError::new(INVALID_PARAMS, message)),
+        };
+        let mut result = json!({ "content": [{ "type": "text", "text": text }], "isError": is_error });
+        if !is_error && let Ok(value @ Value::Object(_)) = serde_json::from_str::<Value>(&text) {
+            result["structuredContent"] = value;
+        }
+        Ok(result)
+    }
+
+    /// The open project the request names.
+    fn project(&self) -> Result<PathBuf, RpcError> {
+        self.resolve_project(self.project)
+    }
+
+    fn resolve_project(&self, requested: Option<&str>) -> Result<PathBuf, RpcError> {
+        let mut roots = self.registry.projects();
+        roots.sort();
+        roots.dedup();
+        if let Some(requested) = requested.filter(|p| !p.trim().is_empty()) {
+            return resolve(&roots, Path::new(requested)).ok_or_else(|| {
+                RpcError::new(
+                    NOT_OPEN,
+                    format!(
+                        "this folder isn't open in OpenIDEA: {requested}. Open projects: {}",
+                        roots.iter().map(|p| p.display().to_string()).collect::<Vec<_>>().join(", ")
+                    ),
+                )
+            });
+        }
+        if roots.len() == 1 {
+            return Ok(roots.remove(0));
+        }
+        Err(RpcError::new(
+            INVALID_PARAMS,
+            format!(
+                "Specify projectPath, X-OpenIDEA-Project or ?project=. Open projects: {}",
+                roots.iter().map(|p| p.display().to_string()).collect::<Vec<_>>().join(", ")
+            ),
+        ))
+    }
+}
+
+/// The project among `roots` containing `path` (the innermost one).
+fn resolve(roots: &[PathBuf], path: &Path) -> Option<PathBuf> {
+    if !path.is_absolute() {
+        return None;
+    }
+    let path = dunce::canonicalize(path).unwrap_or_else(|_| {
+        let mut out = PathBuf::new();
+        for part in path.components() {
+            match part {
+                std::path::Component::CurDir => {}
+                std::path::Component::ParentDir => {
+                    out.pop();
+                }
+                part => out.push(part.as_os_str()),
+            }
+        }
+        out
+    });
+    roots
+        .iter()
+        .filter_map(|root| {
+            let canonical = dunce::canonicalize(root).unwrap_or_else(|_| root.clone());
+            path.starts_with(&canonical).then(|| (canonical.components().count(), root))
+        })
+        .max_by_key(|(depth, _)| *depth)
+        .map(|(_, root)| root.clone())
+}
+
+fn tool_json(tool: &Tool) -> Value {
+    let mut value = json!({
+        "name": tool.name, "description": tool.description, "inputSchema": tool.input_schema,
+        "annotations": { "readOnlyHint": tool.read_only, "destructiveHint": tool.destructive },
+    });
+    if let Some(schema) = &tool.output_schema {
+        value["outputSchema"] = schema.clone();
+    }
+    value
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn the_innermost_open_project_containing_the_path_answers() {
+        let tmp = tempfile::tempdir().unwrap();
+        let outer = dunce::canonicalize(tmp.path()).unwrap();
+        let inner = outer.join("inner");
+        std::fs::create_dir_all(inner.join("src")).unwrap();
+        let roots = [outer.clone(), inner.clone()];
+        assert_eq!(resolve(&roots, &inner.join("src")), Some(inner.clone()));
+        assert_eq!(resolve(&roots, &outer.join("other")), Some(outer.clone()));
+        assert_eq!(resolve(&roots[1..], &outer), None);
+        assert_eq!(resolve(&roots, Path::new("relative/path")), None);
+        // Siblings sharing a prefix are not inside.
+        assert_eq!(resolve(&roots[1..], &outer.join("inner-two")), None);
+    }
+}

crates/ide-mcp/src/server.rs

@@ -0,0 +1,301 @@
+//! The HTTP side: one endpoint, `/mcp`, on the loopback interface.
+
+use crate::discovery::Discovery;
+use crate::{CancellationToken, PROJECT_HEADER, ToolRegistry, protocol};
+use bytes::Bytes;
+use http_body_util::{BodyExt, Full, Limited};
+use hyper::body::Incoming;
+use hyper::header::{self, HeaderMap, HeaderValue};
+use hyper::{Method, Request, Response, StatusCode};
+use std::convert::Infallible;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use tokio::sync::watch;
+
+/// Largest request body.
+const MAX_BODY: usize = 8 << 20;
+
+struct Shared {
+    registry: Arc<dyn ToolRegistry>,
+    token: String,
+    port: u16,
+    requests: protocol::Requests,
+    cancel: CancellationToken,
+}
+
+/// The running server. Stopping it (or dropping it) closes the port and
+/// removes its discovery file.
+pub struct McpServer {
+    port: u16,
+    token: String,
+    discovery: Option<PathBuf>,
+    shutdown: watch::Sender<bool>,
+    cancel: CancellationToken,
+}
+
+impl McpServer {
+    /// Starts listening on `127.0.0.1:<random port>` with a new token, on
+    /// `runtime`, and writes the discovery file at `discovery` if given.
+    pub fn start(
+        registry: Arc<dyn ToolRegistry>,
+        discovery: Option<PathBuf>,
+        runtime: &tokio::runtime::Handle,
+    ) -> std::io::Result<Self> {
+        let listener = std::net::TcpListener::bind(("127.0.0.1", 0))?;
+        listener.set_nonblocking(true)?;
+        let port = listener.local_addr()?.port();
+        let token = new_token()?;
+        let listener = {
+            let _entered = runtime.enter();
+            tokio::net::TcpListener::from_std(listener)?
+        };
+        if let Some(path) = &discovery {
+            let info = Discovery {
+                port,
+                token: token.clone(),
+                pid: std::process::id(),
+                version: env!("CARGO_PKG_VERSION").to_owned(),
+            };
+            info.write(path)?;
+        }
+        let (shutdown, stopped) = watch::channel(false);
+        let cancel = CancellationToken::new();
+        let shared = Arc::new(Shared {
+            registry,
+            token: token.clone(),
+            port,
+            requests: Default::default(),
+            cancel: cancel.clone(),
+        });
+        runtime.spawn(accept(listener, shared, stopped));
+        tracing::info!("MCP server on 127.0.0.1:{port}");
+        Ok(Self { port, token, discovery, shutdown, cancel })
+    }
+
+    pub fn port(&self) -> u16 {
+        self.port
+    }
+
+    /// The bearer token of this run.
+    pub fn token(&self) -> &str {
+        &self.token
+    }
+
+    /// The endpoint URL for `project`.
+    pub fn url(&self, project: &Path) -> String {
+        crate::endpoint_url(self.port, project)
+    }
+
+    pub fn stop(self) {}
+}
+
+impl Drop for McpServer {
+    fn drop(&mut self) {
+        self.cancel.cancel();
+        let _ = self.shutdown.send(true);
+        if let Some(path) = &self.discovery {
+            Discovery::remove_if_ours(path);
+        }
+    }
+}
+
+pub(crate) fn new_token() -> std::io::Result<String> {
+    let mut bytes = [0u8; 32];
+    getrandom::fill(&mut bytes).map_err(|e| std::io::Error::other(e.to_string()))?;
+    Ok(bytes.iter().map(|b| format!("{b:02x}")).collect())
+}
+
+async fn accept(listener: tokio::net::TcpListener, shared: Arc<Shared>, mut stopped: watch::Receiver<bool>) {
+    loop {
+        let stream = tokio::select! {
+            _ = stopped.changed() => return,
+            accepted = listener.accept() => match accepted {
+                Ok((stream, _)) => stream,
+                Err(e) => {
+                    tracing::warn!("MCP server accept: {e}");
+                    tokio::time::sleep(std::time::Duration::from_millis(100)).await;
+                    continue;
+                }
+            },
+        };
+        let (shared, mut stopped) = (shared.clone(), stopped.clone());
+        tokio::spawn(async move {
+            let scope = match new_token() {
+                Ok(scope) => scope,
+                Err(_) => return,
+            };
+            let service = hyper::service::service_fn(move |req| serve(req, shared.clone(), scope.clone()));
+            let conn = hyper::server::conn::http1::Builder::new()
+                .serve_connection(hyper_util::rt::TokioIo::new(stream), service);
+            tokio::pin!(conn);
+            tokio::select! {
+                result = conn.as_mut() => {
+                    if let Err(e) = result {
+                        tracing::debug!("MCP connection: {e}");
+                    }
+                }
+                _ = stopped.changed() => {}
+            }
+        });
+    }
+}
+
+async fn serve(
+    req: Request<Incoming>,
+    shared: Arc<Shared>,
+    scope: String,
+) -> Result<Response<Full<Bytes>>, Infallible> {
+    Ok(respond(req, &shared, scope).await)
+}
+
+type Reply = Response<Full<Bytes>>;
+
+async fn respond(req: Request<Incoming>, shared: &Arc<Shared>, scope: String) -> Reply {
+    if req.uri().path() != "/mcp" {
+        return plain(StatusCode::NOT_FOUND, "not found: the endpoint is /mcp");
+    }
+    if !local_request(req.headers(), shared.port) {
+        return plain(StatusCode::FORBIDDEN, "requests from web pages are refused");
+    }
+    if !authorized(req.headers(), &shared.token) {
+        let mut response = plain(StatusCode::UNAUTHORIZED, "missing or wrong bearer token");
+        response.headers_mut().insert(header::WWW_AUTHENTICATE, HeaderValue::from_static("Bearer"));
+        return response;
+    }
+    if req.method() != Method::POST {
+        // No server-sent event streams: every answer is in the POST's response.
+        let mut response = plain(StatusCode::METHOD_NOT_ALLOWED, "only POST");
+        response.headers_mut().insert(header::ALLOW, HeaderValue::from_static("POST"));
+        return response;
+    }
+    if let Some(version) = req.headers().get("mcp-protocol-version")
+        && !version.to_str().is_ok_and(|v| protocol::SUPPORTED.contains(&v))
+    {
+        return plain(StatusCode::BAD_REQUEST, "unsupported MCP-Protocol-Version");
+    }
+    let scope = req.headers().get("mcp-session-id").and_then(|v| v.to_str().ok()).unwrap_or(&scope).to_owned();
+    let project = project_of(&req);
+    let body = match Limited::new(req.into_body(), MAX_BODY).collect().await {
+        Ok(body) => body.to_bytes(),
+        Err(e) => return plain(StatusCode::PAYLOAD_TOO_LARGE, &format!("request body: {e}")),
+    };
+    let initializing = serde_json::from_slice::<serde_json::Value>(&body)
+        .is_ok_and(|m| m.get("method").and_then(|v| v.as_str()) == Some("initialize"));
+    let response_scope = scope.clone();
+    let registry = shared.registry.clone();
+    let shared = shared.clone();
+    let cancel = shared.cancel.child_token();
+    let _guard = cancel.clone().drop_guard();
+    let handled = tokio::task::spawn_blocking(move || {
+        protocol::handle_body(registry.as_ref(), project.as_deref(), &body, &shared.requests, &scope, cancel)
+    })
+    .await;
+    match handled {
+        Ok(Ok(Some(reply))) => {
+            let mut response = json(StatusCode::OK, &reply);
+            if initializing && let Ok(value) = HeaderValue::from_str(&response_scope) {
+                response.headers_mut().insert("mcp-session-id", value);
+            }
+            response
+        }
+        Ok(Ok(None)) => empty(StatusCode::ACCEPTED),
+        Ok(Err(parse_error)) => json(StatusCode::BAD_REQUEST, &parse_error),
+        Err(e) => plain(StatusCode::INTERNAL_SERVER_ERROR, &format!("the request failed: {e}")),
+    }
+}
+
+/// No `Origin` other than this server's own, and a loopback `Host`: a web
+/// page (DNS rebinding) can't reach the tools even before the token check.
+fn local_request(headers: &HeaderMap, port: u16) -> bool {
+    let ours = |authority: &str| {
+        ["127.0.0.1", "localhost", "[::1]"].iter().any(|host| authority.eq_ignore_ascii_case(&format!("{host}:{port}")))
+    };
+    let host_ok = headers.get(header::HOST).is_none_or(|h| h.to_str().is_ok_and(ours));
+    let origin_ok = headers.get(header::ORIGIN).is_none_or(|o| {
+        o.to_str()
+            .is_ok_and(|o| o.strip_prefix("http://").is_some_and(|authority| ours(authority.trim_end_matches('/'))))
+    });
+    host_ok && origin_ok
+}
+
+fn authorized(headers: &HeaderMap, token: &str) -> bool {
+    let Some(given) = headers.get(header::AUTHORIZATION).and_then(|v| v.to_str().ok()) else { return false };
+    let Some((scheme, given)) = given.trim().split_once(' ') else { return false };
+    scheme.eq_ignore_ascii_case("bearer") && constant_time_eq(given.trim().as_bytes(), token.as_bytes())
+}
+
+fn constant_time_eq(a: &[u8], b: &[u8]) -> bool {
+    a.len() == b.len() && a.iter().zip(b).fold(0u8, |acc, (x, y)| acc | (x ^ y)) == 0
+}
+
+/// The project the request names: the header (UTF-8), else `?project=` (percent-encoded).
+fn project_of(req: &Request<Incoming>) -> Option<String> {
+    if let Some(value) = req.headers().get(PROJECT_HEADER) {
+        return String::from_utf8(value.as_bytes().to_vec()).ok();
+    }
+    req.uri().query()?.split('&').find_map(|pair| {
+        let (key, value) = pair.split_once('=')?;
+        (key == "project").then(|| {
+            let value = value.replace('+', " ");
+            percent_encoding::percent_decode_str(&value).decode_utf8_lossy().into_owned()
+        })
+    })
+}
+
+fn plain(status: StatusCode, text: &str) -> Response<Full<Bytes>> {
+    let mut response = Response::new(Full::new(Bytes::from(text.to_owned())));
+    *response.status_mut() = status;
+    response.headers_mut().insert(header::CONTENT_TYPE, HeaderValue::from_static("text/plain; charset=utf-8"));
+    response
+}
+
+fn json(status: StatusCode, value: &serde_json::Value) -> Response<Full<Bytes>> {
+    let mut response = Response::new(Full::new(Bytes::from(value.to_string())));
+    *response.status_mut() = status;
+    response.headers_mut().insert(header::CONTENT_TYPE, HeaderValue::from_static("application/json"));
+    response
+}
+
+fn empty(status: StatusCode) -> Response<Full<Bytes>> {
+    let mut response = Response::new(Full::new(Bytes::new()));
+    *response.status_mut() = status;
+    response
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn only_loopback_hosts_and_origins_of_this_server_pass() {
+        let headers = |pairs: &[(header::HeaderName, &str)]| {
+            let mut h = HeaderMap::new();
+            for (k, v) in pairs {
+                h.insert(k.clone(), HeaderValue::from_str(v).unwrap());
+            }
+            h
+        };
+        assert!(local_request(&headers(&[]), 80));
+        assert!(local_request(&headers(&[(header::HOST, "127.0.0.1:80")]), 80));
+        assert!(local_request(
+            &headers(&[(header::HOST, "localhost:80"), (header::ORIGIN, "http://localhost:80")]),
+            80
+        ));
+        assert!(!local_request(&headers(&[(header::HOST, "evil.example:80")]), 80));
+        assert!(!local_request(&headers(&[(header::HOST, "127.0.0.1:81")]), 80));
+        assert!(!local_request(&headers(&[(header::ORIGIN, "https://evil.example")]), 80));
+        assert!(!local_request(&headers(&[(header::ORIGIN, "null")]), 80));
+    }
+
+    #[test]
+    fn bearer_tokens_compare_exactly() {
+        let mut h = HeaderMap::new();
+        assert!(!authorized(&h, "abc"));
+        h.insert(header::AUTHORIZATION, HeaderValue::from_static("Bearer abc"));
+        assert!(authorized(&h, "abc"));
+        assert!(!authorized(&h, "abcd"));
+        h.insert(header::AUTHORIZATION, HeaderValue::from_static("Basic abc"));
+        assert!(!authorized(&h, "abc"));
+        assert_eq!(new_token().unwrap().len(), 64);
+    }
+}

crates/ide-mcp/src/stdio.rs

@@ -0,0 +1,130 @@
+//! The stdio bridge: `<app exe> --mcp-stdio [--project <path>]`. MCP clients
+//! that start servers as processes (and configurations that must not hold a
+//! token) talk newline-delimited JSON-RPC to it; it relays each message to the
+//! running IDE's server, found through the discovery file.
+
+use crate::discovery::Discovery;
+use crate::protocol::{NOT_OPEN, error_response};
+use bytes::Bytes;
+use http_body_util::{BodyExt, Full};
+use hyper::{Request, StatusCode, header};
+use serde_json::Value;
+use std::path::{Path, PathBuf};
+use tokio::io::{AsyncBufRead, AsyncBufReadExt, AsyncWrite, AsyncWriteExt};
+
+/// Runs the bridge on this process's stdin and stdout until stdin closes.
+/// `project` defaults to the current directory. Returns the exit code.
+pub fn run(discovery: &Path, project: Option<PathBuf>) -> i32 {
+    let cwd = std::env::current_dir().unwrap_or_default();
+    let project = project.map_or_else(|| cwd.clone(), |p| if p.is_absolute() { p } else { cwd.join(p) });
+    let runtime = match tokio::runtime::Builder::new_current_thread().enable_all().build() {
+        Ok(rt) => rt,
+        Err(e) => {
+            eprintln!("openidea --mcp-stdio: {e}");
+            return 1;
+        }
+    };
+    let stdin = tokio::io::BufReader::new(tokio::io::stdin());
+    match runtime.block_on(bridge(discovery, &project, stdin, tokio::io::stdout())) {
+        Ok(()) => 0,
+        Err(e) => {
+            eprintln!("openidea --mcp-stdio: {e}");
+            1
+        }
+    }
+}
+
+/// Relays each line of `input` (a JSON-RPC message or batch) to the IDE and
+/// writes its answer, if any, as one line to `output`.
+pub async fn bridge<R, W>(discovery: &Path, project: &Path, input: R, mut output: W) -> std::io::Result<()>
+where
+    R: AsyncBufRead + Unpin,
+    W: AsyncWrite + Unpin,
+{
+    let scope = crate::server::new_token()?;
+    let mut lines = input.lines();
+    let mut pending = tokio::task::JoinSet::new();
+    let mut eof = false;
+    loop {
+        let reply = tokio::select! {
+            line = lines.next_line(), if !eof => {
+                let Some(line) = line? else { eof = true; continue };
+                if line.trim().is_empty() { continue; }
+                match serde_json::from_str::<Value>(&line) {
+                    Ok(message) => {
+                        let (discovery, project, scope) = (discovery.to_owned(), project.to_owned(), scope.clone());
+                        pending.spawn(async move { relay(&discovery, &project, &message, &scope).await });
+                        continue;
+                    }
+                    Err(e) => Some(error_response(Value::Null, -32700, &format!("not JSON: {e}"))),
+                }
+            }
+            reply = pending.join_next(), if !pending.is_empty() => match reply { Some(reply) => reply.map_err(std::io::Error::other)?, None => None },
+            else => break,
+        };
+        if let Some(reply) = reply {
+            output.write_all(reply.to_string().as_bytes()).await?;
+            output.write_all(b"\n").await?;
+            output.flush().await?;
+        }
+    }
+    Ok(())
+}
+
+/// The IDE's answer to `message`, or an error response for each request in
+/// it when the IDE can't be reached.
+async fn relay(discovery: &Path, project: &Path, message: &Value, scope: &str) -> Option<Value> {
+    let failure = match post(discovery, project, message, scope).await {
+        Ok((StatusCode::ACCEPTED, _)) => return None,
+        Ok((_, body)) if !body.is_empty() => match serde_json::from_slice::<Value>(&body) {
+            Ok(reply) => return Some(reply),
+            Err(_) => String::from_utf8_lossy(&body).trim().to_owned(),
+        },
+        Ok((status, _)) => format!("OpenIDEA answered {status}"),
+        Err(e) => e,
+    };
+    let errors: Vec<Value> = requests(message).into_iter().map(|id| error_response(id, NOT_OPEN, &failure)).collect();
+    match (message, errors.len()) {
+        (_, 0) => None,
+        (Value::Array(_), _) => Some(Value::Array(errors)),
+        (_, _) => errors.into_iter().next(),
+    }
+}
+
+/// Ids of the requests in a message or batch (notifications have none).
+fn requests(message: &Value) -> Vec<Value> {
+    let ids = |m: &Value| m.get("method").is_some().then(|| m.get("id").cloned()).flatten();
+    match message {
+        Value::Array(batch) => batch.iter().filter_map(ids).collect(),
+        m => ids(m).into_iter().collect(),
+    }
+}
+
+/// POSTs `message` to the server in the discovery file; a message for the
+/// user when that fails.
+async fn post(discovery: &Path, project: &Path, message: &Value, scope: &str) -> Result<(StatusCode, Bytes), String> {
+    let not_running = || {
+        format!(
+            "OpenIDEA's MCP server is not running. Start OpenIDEA, open {} in it, and turn on Settings › Tools › MCP Server",
+            project.display()
+        )
+    };
+    let info = Discovery::read(discovery).map_err(|_| not_running())?;
+    let stream = tokio::net::TcpStream::connect(("127.0.0.1", info.port)).await.map_err(|_| not_running())?;
+    let (mut sender, conn) = hyper::client::conn::http1::handshake(hyper_util::rt::TokioIo::new(stream))
+        .await
+        .map_err(|e| format!("cannot reach OpenIDEA: {e}"))?;
+    tokio::spawn(conn);
+    let request = Request::post(format!("/mcp?project={}", crate::encode_query(&project.to_string_lossy())))
+        .header(header::HOST, format!("127.0.0.1:{}", info.port))
+        .header(header::AUTHORIZATION, format!("Bearer {}", info.token))
+        .header("mcp-session-id", scope)
+        .header(header::CONTENT_TYPE, "application/json")
+        .header(header::ACCEPT, "application/json, text/event-stream")
+        .body(Full::new(Bytes::from(message.to_string())))
+        .map_err(|e| e.to_string())?;
+    let response = sender.send_request(request).await.map_err(|e| format!("cannot reach OpenIDEA: {e}"))?;
+    let status = response.status();
+    let body = response.into_body().collect().await.map_err(|e| format!("OpenIDEA's answer: {e}"))?.to_bytes();
+    Ok((status, body))
+}

crates/ide-mcp/tests/server.rs

@@ -0,0 +1,350 @@
+//! The server over real HTTP, and the stdio bridge in front of it, with a
+//! registry standing in for the IDE host.
+
+use ide_mcp::{Discovery, McpServer, Tool, ToolCallError, ToolRegistry, discovery_path, stdio};
+use serde_json::{Value, json};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+
+struct Registry {
+    project: PathBuf,
+}
+
+impl ToolRegistry for Registry {
+    fn projects(&self) -> Vec<PathBuf> {
+        vec![self.project.clone()]
+    }
+
+    fn tools(&self, project: &Path) -> Result<Vec<Tool>, String> {
+        assert_eq!(project, self.project);
+        Ok(vec![Tool {
+            name: "echo".into(),
+            description: "Says it back".into(),
+            input_schema: json!({ "type": "object", "properties": { "text": { "type": "string" } } }),
+            read_only: true,
+            destructive: false,
+            output_schema: None,
+        }])
+    }
+
+    fn call(
+        &self,
+        project: &Path,
+        name: &str,
+        arguments: &str,
+        _cancel: ide_mcp::CancellationToken,
+    ) -> Result<String, ToolCallError> {
+        let args: Value = serde_json::from_str(arguments).unwrap();
+        match name {
+            "echo" if args["text"] == "fail" => Err(ToolCallError::Failed("it failed".into())),
+            "echo" => Ok(format!("{} in {}", args["text"].as_str().unwrap_or(""), project.display())),
+            _ => Err(ToolCallError::UnknownTool(format!("no tool {name:?}"))),
+        }
+    }
+}
+
+struct Setup {
+    _tmp: tempfile::TempDir,
+    project: PathBuf,
+    discovery: PathBuf,
+    server: Option<McpServer>,
+}
+
+fn setup() -> Setup {
+    let tmp = tempfile::tempdir().unwrap();
+    let project = dunce::canonicalize(tmp.path()).unwrap().join("project");
+    std::fs::create_dir_all(project.join("src")).unwrap();
+    let discovery = discovery_path(&tmp.path().join("app-data"));
+    let registry = Arc::new(Registry { project: project.clone() });
+    let server = McpServer::start(registry, Some(discovery.clone()), &tokio::runtime::Handle::current()).unwrap();
+    Setup { _tmp: tmp, project, discovery, server: Some(server) }
+}
+
+impl Setup {
+    fn server(&self) -> &McpServer {
+        self.server.as_ref().unwrap()
+    }
+}
+
+/// A raw HTTP/1.1 exchange: (status, body).
+async fn http(port: u16, request: &str) -> (u16, String) {
+    let mut stream = tokio::net::TcpStream::connect(("127.0.0.1", port)).await.unwrap();
+    stream.write_all(request.as_bytes()).await.unwrap();
+    let mut out = String::new();
+    stream.read_to_string(&mut out).await.unwrap();
+    let status = out.split(' ').nth(1).unwrap().parse().unwrap();
+    let body = out.split_once("\r\n\r\n").map(|(_, b)| b.to_owned()).unwrap_or_default();
+    (status, body)
+}
+
+/// POSTs `body` to `path` with extra header lines; closes the connection after.
+async fn post(s: &Setup, path: &str, headers: &[&str], body: &Value) -> (u16, String) {
+    let body = body.to_string();
+    let port = s.server().port();
+    let mut head = format!(
+        "POST {path} HTTP/1.1\r\nHost: 127.0.0.1:{port}\r\nContent-Type: application/json\r\nAccept: application/json, text/event-stream\r\nContent-Length: {}\r\nConnection: close\r\n",
+        body.len()
+    );
+    for h in headers {
+        head.push_str(h);
+        head.push_str("\r\n");
+    }
+    http(port, &format!("{head}\r\n{body}")).await
+}
+
+fn bearer(s: &Setup) -> String {
+    format!("Authorization: Bearer {}", s.server().token())
+}
+
+async fn rpc(s: &Setup, method: &str, params: Value) -> Value {
+    let project = format!("X-OpenIDEA-Project: {}", s.project.display());
+    let (status, body) = post(
+        s,
+        "/mcp",
+        &[&bearer(s), &project],
+        &json!({ "jsonrpc": "2.0", "id": 7, "method": method, "params": params }),
+    )
+    .await;
+    assert_eq!(status, 200, "{body}");
+    let reply: Value = serde_json::from_str(&body).unwrap();
+    assert_eq!(reply["id"], 7);
+    reply
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn initialize_list_and_call_tools() {
+    let s = setup();
+    let init = rpc(
+        &s,
+        "initialize",
+        json!({ "protocolVersion": "2025-03-26", "capabilities": {}, "clientInfo": { "name": "t", "version": "1" } }),
+    )
+    .await;
+    assert_eq!(init["result"]["protocolVersion"], "2025-03-26");
+    assert_eq!(init["result"]["serverInfo"]["name"], "OpenIDEA");
+    assert!(init["result"]["capabilities"]["tools"].is_object());
+    let newer = rpc(&s, "initialize", json!({ "protocolVersion": "2099-01-01" })).await;
+    assert_eq!(newer["result"]["protocolVersion"], "2025-06-18");
+
+    // Notifications are accepted without a body.
+    let (status, body) =
+        post(&s, "/mcp", &[&bearer(&s)], &json!({ "jsonrpc": "2.0", "method": "notifications/initialized" })).await;
+    assert_eq!((status, body.as_str()), (202, ""));
+
+    let list = rpc(&s, "tools/list", json!({})).await;
+    let tool = &list["result"]["tools"][0];
+    assert_eq!(tool["name"], "echo");
+    assert_eq!(tool["inputSchema"]["type"], "object");
+    assert_eq!(tool["annotations"], json!({ "readOnlyHint": true, "destructiveHint": false }));
+
+    let call = rpc(&s, "tools/call", json!({ "name": "echo", "arguments": { "text": "hi" } })).await;
+    let expected = format!("hi in {}", s.project.display());
+    assert_eq!(call["result"], json!({ "content": [{ "type": "text", "text": expected }], "isError": false }));
+    let failed = rpc(&s, "tools/call", json!({ "name": "echo", "arguments": { "text": "fail" } })).await;
+    assert_eq!(failed["result"]["isError"], true);
+    assert_eq!(failed["result"]["content"][0]["text"], "it failed");
+    let unknown = rpc(&s, "tools/call", json!({ "name": "nope" })).await;
+    assert_eq!(unknown["error"]["code"], -32602);
+    assert_eq!(rpc(&s, "ping", json!({})).await["result"], json!({}));
+    assert_eq!(rpc(&s, "resources/list", json!({})).await["error"]["code"], -32601);
+
+    // The project by query, from a folder inside it; a batch.
+    let query = format!("/mcp?project={}", ide_mcp::endpoint_url(1, &s.project.join("src")).split_once('=').unwrap().1);
+    let batch = json!([
+        { "jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": { "name": "echo", "arguments": { "text": "a" } } },
+        { "jsonrpc": "2.0", "method": "notifications/cancelled", "params": { "requestId": 9 } },
+        { "jsonrpc": "2.0", "id": 2, "method": "ping" }
+    ]);
+    let (status, body) = post(&s, &query, &[&bearer(&s)], &batch).await;
+    assert_eq!(status, 200, "{body}");
+    let replies: Value = serde_json::from_str(&body).unwrap();
+    assert_eq!(replies.as_array().unwrap().len(), 2);
+    assert_eq!(replies[0]["result"]["content"][0]["text"], expected.replacen("hi", "a", 1));
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn requests_without_the_token_or_from_web_pages_are_refused() {
+    let s = setup();
+    let ping = json!({ "jsonrpc": "2.0", "id": 1, "method": "ping" });
+    assert_eq!(post(&s, "/mcp", &[], &ping).await.0, 401);
+    assert_eq!(post(&s, "/mcp", &["Authorization: Bearer wrong"], &ping).await.0, 401);
+    assert_eq!(post(&s, "/mcp", &[&bearer(&s), "Origin: https://evil.example"], &ping).await.0, 403);
+    let port = s.server().port();
+    let (status, _) = http(
+        port,
+        &format!(
+            "POST /mcp HTTP/1.1\r\nHost: evil.example:{port}\r\nContent-Length: 2\r\nConnection: close\r\n\r\n{{}}"
+        ),
+    )
+    .await;
+    assert_eq!(status, 403, "a rebound host name");
+    // No SSE stream to open; other paths don't exist.
+    let get = format!("GET /mcp HTTP/1.1\r\nHost: 127.0.0.1:{port}\r\n{}\r\nConnection: close\r\n\r\n", bearer(&s));
+    assert_eq!(http(port, &get).await.0, 405);
+    assert_eq!(post(&s, "/other", &[&bearer(&s)], &ping).await.0, 404);
+    assert_eq!(post(&s, "/mcp", &[&bearer(&s), "MCP-Protocol-Version: 1999-01-01"], &ping).await.0, 400);
+    let (status, body) = post(&s, "/mcp", &[&bearer(&s)], &json!("{")).await;
+    assert_eq!(status, 200, "a JSON string is a message, just not a request: {body}");
+    let garbage = format!(
+        "POST /mcp HTTP/1.1\r\nHost: 127.0.0.1:{port}\r\n{}\r\nContent-Length: 1\r\nConnection: close\r\n\r\n{{",
+        bearer(&s)
+    );
+    let (status, body) = http(port, &garbage).await;
+    assert_eq!(status, 400);
+    assert_eq!(serde_json::from_str::<Value>(&body).unwrap()["error"]["code"], -32700);
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn folders_that_are_not_open_are_named_in_the_error() {
+    let s = setup();
+    let elsewhere = s.project.parent().unwrap().join("elsewhere");
+    let header = format!("X-OpenIDEA-Project: {}", elsewhere.display());
+    let (status, body) =
+        post(&s, "/mcp", &[&bearer(&s), &header], &json!({"jsonrpc":"2.0","id":3,"method":"tools/list"})).await;
+    assert_eq!(status, 200);
+    let reply: Value = serde_json::from_str(&body).unwrap();
+    assert!(reply["error"]["message"].as_str().unwrap().contains("isn't open in OpenIDEA"));
+    let (_, body) = post(&s, "/mcp", &[&bearer(&s)], &json!({"jsonrpc":"2.0","id":3,"method":"tools/list"})).await;
+    assert!(serde_json::from_str::<Value>(&body).unwrap()["result"]["tools"].is_array());
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn the_discovery_file_lives_while_the_server_runs() {
+    let mut s = setup();
+    let info = Discovery::read(&s.discovery).unwrap();
+    assert_eq!((info.port, info.token.as_str(), info.pid), (s.server().port(), s.server().token(), std::process::id()));
+    let port = info.port;
+    s.server.take().unwrap().stop();
+    assert!(!s.discovery.exists());
+    tokio::time::sleep(std::time::Duration::from_millis(50)).await;
+    assert!(tokio::net::TcpStream::connect(("127.0.0.1", port)).await.is_err(), "the port is closed");
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn the_stdio_bridge_relays_lines_and_explains_a_missing_ide() {
+    let mut s = setup();
+    let input = [
+        json!({ "jsonrpc": "2.0", "id": 1, "method": "initialize", "params": { "protocolVersion": "2025-06-18" } }),
+        json!({ "jsonrpc": "2.0", "method": "notifications/initialized" }),
+        json!({ "jsonrpc": "2.0", "id": 2, "method": "tools/call", "params": { "name": "echo", "arguments": { "text": "x" } } }),
+    ]
+    .iter()
+    .map(|m| format!("{m}\n"))
+    .collect::<String>()
+        + "\n";
+    let mut output = Vec::new();
+    stdio::bridge(&s.discovery, &s.project.join("src"), input.as_bytes(), &mut output).await.unwrap();
+    let mut replies: Vec<Value> =
+        String::from_utf8(output).unwrap().lines().map(|l| serde_json::from_str(l).unwrap()).collect();
+    replies.sort_by_key(|r| r["id"].as_i64());
+    assert_eq!(replies.len(), 2, "nothing for the notification: {replies:?}");
+    assert_eq!(replies[0]["result"]["protocolVersion"], "2025-06-18");
+    assert_eq!(replies[1]["result"]["content"][0]["text"], format!("x in {}", s.project.display()));
+
+    // The IDE quit: each request gets an error saying what to do.
+    s.server.take().unwrap().stop();
+    let mut output = Vec::new();
+    let input = format!("{}\n", json!({ "jsonrpc": "2.0", "id": 5, "method": "initialize", "params": {} }));
+    stdio::bridge(&s.discovery, &s.project, input.as_bytes(), &mut output).await.unwrap();
+    let reply: Value = serde_json::from_slice(&output).unwrap();
+    assert_eq!(reply["id"], 5);
+    assert!(reply["error"]["message"].as_str().unwrap().contains("MCP server is not running"), "{reply}");
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn routing_an_argument_overrides_the_header_and_ambiguity_lists_projects() {
+    struct Many(Vec<PathBuf>);
+    impl ToolRegistry for Many {
+        fn projects(&self) -> Vec<PathBuf> {
+            self.0.clone()
+        }
+        fn tools(&self, _: &Path) -> Result<Vec<Tool>, String> {
+            Ok(Vec::new())
+        }
+        fn call(
+            &self,
+            project: &Path,
+            _: &str,
+            _: &str,
+            _: ide_mcp::CancellationToken,
+        ) -> Result<String, ToolCallError> {
+            Ok(json!({"project":project}).to_string())
+        }
+    }
+    let mut s = setup();
+    s.server.take().unwrap().stop();
+    let second = s.project.parent().unwrap().join("second");
+    std::fs::create_dir_all(second.join("nested")).unwrap();
+    s.server = Some(
+        McpServer::start(
+            Arc::new(Many(vec![s.project.clone(), second.clone()])),
+            None,
+            &tokio::runtime::Handle::current(),
+        )
+        .unwrap(),
+    );
+    let (_, body) = post(&s, "/mcp", &[&bearer(&s)], &json!({"jsonrpc":"2.0","id":1,"method":"tools/list"})).await;
+    let reply: Value = serde_json::from_str(&body).unwrap();
+    let message = reply["error"]["message"].as_str().unwrap();
+    assert!(message.contains(s.project.to_str().unwrap()) && message.contains(second.to_str().unwrap()));
+    let result = rpc(&s, "tools/call", json!({"name":"where","arguments":{"projectPath":second.join("nested")}})).await;
+    assert_eq!(result["result"]["structuredContent"]["project"], json!(second));
+    let unknown = rpc(&s, "tools/call", json!({"name":"where","arguments":{"projectPath":"/unknown/project"}})).await;
+    assert_eq!(unknown["error"]["code"], -32001);
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn cancellation_reaches_a_running_tool_without_affecting_another_client() {
+    struct Waiting(Arc<tokio::sync::Notify>);
+    impl ToolRegistry for Waiting {
+        fn projects(&self) -> Vec<PathBuf> {
+            vec![PathBuf::from("/project")]
+        }
+        fn tools(&self, _: &Path) -> Result<Vec<Tool>, String> {
+            Ok(Vec::new())
+        }
+        fn call(
+            &self,
+            _: &Path,
+            _: &str,
+            _: &str,
+            cancel: ide_mcp::CancellationToken,
+        ) -> Result<String, ToolCallError> {
+            self.0.notify_one();
+            tokio::runtime::Handle::current().block_on(cancel.cancelled());
+            Err(ToolCallError::Failed("cancelled".into()))
+        }
+    }
+    let mut s = setup();
+    s.server.take().unwrap().stop();
+    let started = Arc::new(tokio::sync::Notify::new());
+    s.server =
+        Some(McpServer::start(Arc::new(Waiting(started.clone())), None, &tokio::runtime::Handle::current()).unwrap());
+    let body = json!({"jsonrpc":"2.0","id":11,"method":"tools/call","params":{"name":"wait"}});
+    let auth = bearer(&s);
+    let headers = [&*auth, "Mcp-Session-Id: client-one"];
+    let call = post(&s, "/mcp", &headers, &body);
+    let cancel = async {
+        started.notified().await;
+        let notification = json!({"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":11}});
+        assert_eq!(post(&s, "/mcp", &[&bearer(&s), "Mcp-Session-Id: client-two"], &notification).await.0, 202);
+        assert_eq!(post(&s, "/mcp", &[&bearer(&s), "Mcp-Session-Id: client-one"], &notification).await.0, 202);
+    };
+    let ((status, body), ()) =
+        tokio::time::timeout(std::time::Duration::from_secs(5), async { tokio::join!(call, cancel) }).await.unwrap();
+    assert_eq!(status, 200);
+    assert_eq!(serde_json::from_str::<Value>(&body).unwrap()["result"]["isError"], true);
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn a_cancellation_that_arrives_before_the_call_is_remembered() {
+    let s = setup();
+    let auth = bearer(&s);
+    let headers = [auth.as_str(), "Mcp-Session-Id: early-cancel"];
+    let notification = json!({"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":8}});
+    assert_eq!(post(&s, "/mcp", &headers, &notification).await.0, 202);
+    let call = json!({"jsonrpc":"2.0","id":8,"method":"tools/call","params":{"name":"echo","arguments":{"text":"hi"}}});
+    let (_, body) = post(&s, "/mcp", &headers, &call).await;
+    assert_eq!(serde_json::from_str::<Value>(&body).unwrap()["result"]["isError"], true);
+}

crates/ide-run/src/detect.rs

@@ -1168,6 +1168,7 @@ fn detect_ruby(root: &Path, out: &mut Vec<RunConfig>) {
             ("ruby".into(), Vec::new()),
             &["bin/rails", "server"],
         );
+        c = c.debug("rdbg");
         c.extras.folder = Some("Rails".into());
         out.push(c);
     }
@@ -1180,12 +1181,15 @@ fn detect_ruby(root: &Path, out: &mut Vec<RunConfig>) {
             if task == "test" || task == "spec" || task.ends_with(":test") || task.ends_with(":spec") {
                 c = c.test();
             }
+            c = c.debug("rdbg");
             c.extras.folder = Some("Rake".into());
             out.push(c);
         }
     }
     if uses_rspec(root) {
-        out.push(ruby_config("rspec".into(), "rspec".into(), "rspec", ruby_tool(root, "rspec"), &[]).test());
+        out.push(
+            ruby_config("rspec".into(), "rspec".into(), "rspec", ruby_tool(root, "rspec"), &[]).test().debug("rdbg"),
+        );
     } else if root.join("test").is_dir() && !out.iter().any(|c| c.id == "rake:test") {
         // Minitest / Test::Unit without a `test` Rake task: load every test file under `test/`.
         let mut args = Vec::new();
@@ -1196,7 +1200,11 @@ fn detect_ruby(root: &Path, out: &mut Vec<RunConfig>) {
         }
         args.extend(["-e".to_owned(), MINITEST_RUNNER.to_owned(), "test".to_owned()]);
         let extra: Vec<&str> = args.iter().map(String::as_str).collect();
-        out.push(ruby_config("minitest".into(), "minitest".into(), "ruby", ruby_tool(root, "ruby"), &extra).test());
+        out.push(
+            ruby_config("minitest".into(), "minitest".into(), "ruby", ruby_tool(root, "ruby"), &extra)
+                .test()
+                .debug("rdbg"),
+        );
     }
 }
 

crates/ide-run/src/process.rs

@@ -57,6 +57,7 @@ struct Entry {
     stop: Option<StopCommand>,
     output: OutputFn,
     exited: AtomicBool,
+    code: Mutex<Option<i32>>,
     stopping: AtomicBool,
 }
 
@@ -436,6 +437,7 @@ impl ProcessManager {
             stop,
             output: on_output.clone(),
             exited: AtomicBool::new(false),
+            code: Mutex::new(None),
             stopping: AtomicBool::new(false),
         });
         self.register(entry.clone());
@@ -547,6 +549,7 @@ impl ProcessManager {
             stop,
             output: on_output.clone(),
             exited: AtomicBool::new(false),
+            code: Mutex::new(None),
             stopping: AtomicBool::new(false),
         });
         self.register(entry.clone());
@@ -685,6 +688,15 @@ impl ProcessManager {
         Ok(())
     }
 
+    /// Returns `None` while running, or the exit code once output has drained.
+    pub fn exit_code(&self, id: RunId) -> IdeResult<Option<Option<i32>>> {
+        let entry = self.entry(id)?;
+        if !entry.exited.load(Ordering::Acquire) {
+            return Ok(None);
+        }
+        Ok(Some(*entry.code.lock()))
+    }
+
     pub fn list(&self) -> Vec<RunInfo> {
         self.runs.lock().values().map(|e| e.info()).collect()
     }
@@ -1078,6 +1090,7 @@ fn spawn_pump(
                 std::thread::sleep(Duration::from_millis(50));
             }
         }
+        *entry.code.lock() = code;
         entry.exited.store(true, Ordering::Release);
         tracing::debug!(id = %entry.id, ?code, "run exited");
         sink.emit(IdeEvent::RunExited { run: entry.id, code });

crates/ide-run/src/tomcat.rs

@@ -395,6 +395,10 @@ fn canonical_path(path: &Path) -> IdeResult<PathBuf> {
     let mut resolved = PathBuf::new();
     for component in std::path::absolute(path)?.components() {
         match component {
+            std::path::Component::Prefix(_) => {
+                resolved.push(component);
+                continue;
+            }
             std::path::Component::ParentDir => {
                 resolved.pop();
             }

crates/ide-run/tests/detect.rs

@@ -1063,6 +1063,7 @@ task default: :build
     assert_eq!(cmdline(find(&c, "rspec")), "bundle exec rspec");
     assert!(find(&c, "rspec").is_test);
     assert_eq!(find(&c, "rake:build").extras.folder.as_deref(), Some("Rake"));
+    assert!(c.iter().all(|c| c.debug_adapter.as_deref() == Some("rdbg")));
 }
 
 #[test]
@@ -1077,6 +1078,7 @@ fn ruby_minitest_projects_get_a_test_runner() {
         ("bundle", &["exec", "ruby", "-Ilib", "-Itest"].map(String::from)[..])
     );
     assert_eq!(m.args.last().map(String::as_str), Some("test"));
+    assert_eq!(m.debug_adapter.as_deref(), Some("rdbg"));
     // A `test` Rake task or RSpec already runs the tests.
     let dir = project(&[("Rakefile", "task :test\n"), ("test/a_test.rb", "")]);
     assert!(!ids(&detect(dir.path())).contains(&"minitest"));

crates/ide-sdk/src/apply.rs

@@ -408,33 +408,34 @@ pub fn gradle_env(
 }
 
 /// Maven options from settings, placed before the goals: `-s <settings.xml>`,
-/// `-Dmaven.repo.local=<dir>` and `-T <count>` (the thread count).
+/// `-t <toolchains.xml>`, `-Dmaven.repo.local=<dir>`, `-T <count>` and `-P <profiles>`.
 pub fn maven_options(root: &Path, s: &Settings) -> Vec<String> {
     let m = &s.languages.java.maven;
     let mut out = Vec::new();
     if let Some(file) = setting_path(root, &m.user_settings) {
         out.extend(["-s".to_owned(), file.to_string_lossy().into_owned()]);
     }
+    if let Some(file) = setting_path(root, &m.toolchains) {
+        out.extend(["-t".to_owned(), file.to_string_lossy().into_owned()]);
+    }
     if let Some(dir) = setting_path(root, &m.local_repository) {
         out.push(format!("-Dmaven.repo.local={}", dir.to_string_lossy()));
     }
     if let Some(threads) = m.thread_count() {
         out.extend(["-T".to_owned(), threads.to_owned()]);
     }
+    if let Some(profiles) = non_empty(&m.active_profiles) {
+        out.extend(["-P".to_owned(), profiles.to_owned()]);
+    }
     out
 }
 
 fn maven_settings_prefixes(args: &[String]) -> Vec<usize> {
     let mut prefixes = vec![0];
     let mut i = 0;
-    while let Some(arg) = args.get(i) {
-        if (arg == "-s" || arg == "-T") && args.get(i + 1).is_some() {
-            i += 2;
-        } else if arg.starts_with("-Dmaven.repo.local=") {
-            i += 1;
-        } else {
-            break;
-        }
+    while i < args.len() {
+        let Some(n) = maven_option_len(&args[i..]) else { break };
+        i += n;
         prefixes.push(i);
     }
     prefixes
@@ -1110,43 +1111,62 @@ fn is_python_command(cmd: &str) -> bool {
 
 const PY_RUNNERS: [&str; 3] = ["uv", "poetry", "pdm"];
 
-/// [`maven_options`] as the groups they are passed in (`-s <file>`, `-Dmaven.repo.local=…`,
-/// `-T <count>`).
+fn maven_option_flag(arg: &str) -> Option<&'static str> {
+    for (short, long) in
+        [("-s", "--settings"), ("-t", "--toolchains"), ("-T", "--threads"), ("-P", "--activate-profiles")]
+    {
+        if arg.starts_with(short) || arg == long || arg.starts_with(&format!("{long}=")) {
+            return Some(short);
+        }
+    }
+    arg.starts_with("-Dmaven.repo.local=").then_some("-Dmaven.repo.local")
+}
+
+fn maven_option_len(args: &[String]) -> Option<usize> {
+    let arg = args.first()?;
+    maven_option_flag(arg)?;
+    let separate = matches!(
+        arg.as_str(),
+        "-s" | "--settings" | "-t" | "--toolchains" | "-T" | "--threads" | "-P" | "--activate-profiles"
+    );
+    Some(if separate { 2.min(args.len()) } else { 1 })
+}
+
+/// [`maven_options`] grouped with each option's value.
 fn maven_option_groups(options: &[String]) -> Vec<&[String]> {
     let mut groups = Vec::new();
     let mut i = 0;
     while i < options.len() {
-        let n = if options[i] == "-s" || options[i] == "-T" { 2.min(options.len() - i) } else { 1 };
+        let n = maven_option_len(&options[i..]).unwrap_or(1);
         groups.push(&options[i..i + n]);
         i += n;
     }
     groups
 }
 
-/// Whether `args` set what `group` sets: a user settings file, the local
-/// repository, or the thread count.
+/// Whether the configuration sets the same option, including attached and long forms.
 fn sets_maven_option(args: &[String], group: &[String]) -> bool {
-    match group.first().map(String::as_str) {
-        Some("-s") => args.iter().any(|a| a == "-s" || a == "--settings" || a.starts_with("--settings=")),
-        // `-T 4`, `--threads 4`, `-T4` and `--threads=4` all set the thread count.
-        Some("-T") => args.iter().any(|a| {
-            a == "-T" || a == "--threads" || a.starts_with("--threads=") || (a.starts_with("-T") && a.len() > 2)
-        }),
-        Some(flag) => {
-            let key = flag.split_once('=').map_or(flag, |(k, _)| k);
-            args.iter().any(|a| a.split_once('=').map_or(a.as_str(), |(k, _)| k) == key)
-                || args
-                    .windows(2)
-                    .any(|a| a[0] == "-D" && format!("-D{}", a[1].split('=').next().unwrap_or_default()) == key)
-        }
-        None => true,
-    }
+    let Some(flag) = group.first().and_then(|a| maven_option_flag(a)) else { return true };
+    args.iter().any(|a| maven_option_flag(a) == Some(flag))
+        || (flag == "-Dmaven.repo.local"
+            && args.windows(2).any(|a| a[0] == "-D" && a[1].starts_with("maven.repo.local=")))
 }
 
-/// Settings › Maven's options ahead of the goals, each unless the configuration sets it itself.
-fn add_maven_options(args: &mut Vec<String>, options: &[String]) {
-    let missing: Vec<String> =
-        maven_option_groups(options).into_iter().filter(|g| !sets_maven_option(args, g)).flatten().cloned().collect();
+/// Settings options precede the goals. Tool-window checkbox profiles are additive;
+/// profiles explicitly typed in the configuration replace the Settings profiles.
+fn add_maven_options(args: &mut Vec<String>, options: &[String], additive_profiles: bool) {
+    let missing: Vec<String> = maven_option_groups(options)
+        .into_iter()
+        .filter(|g| {
+            if additive_profiles && g[0] == "-P" {
+                !args.windows(g.len()).any(|w| w == *g)
+            } else {
+                !sets_maven_option(args, g)
+            }
+        })
+        .flatten()
+        .cloned()
+        .collect();
     args.splice(0..0, missing);
 }
 
@@ -1315,7 +1335,11 @@ pub fn apply_to_run_configs(configs: &mut [RunConfig], root: &Path, s: &Settings
                 {
                     c.command = mvn.to_string_lossy().into_owned();
                 }
-                add_maven_options(&mut c.args, &mvn_options);
+                let additive_profiles = generated_maven_goal(c)
+                    && c.id.split_once(".xml:").is_some_and(|(_, goals)| {
+                        !goals.split_whitespace().any(|a| maven_option_flag(a) == Some("-P"))
+                    });
+                add_maven_options(&mut c.args, &mvn_options, additive_profiles);
             }
             _ => {}
         }

crates/ide-sdk/src/maven_profiles.rs

@@ -12,15 +12,15 @@ use std::path::{Path, PathBuf};
 const PREFIX: &str = "jdtls-maven-settings-";
 
 /// Points jdtls at a user `settings.xml` activating `profiles` (`-P` entries of the
-/// last Maven sync), written to `dir`. Through `settings`, so a running server
+/// last Maven sync), combined with Settings profiles and written to `dir`. Through `settings`, so a running server
 /// re-imports its Maven projects instead of restarting. `!id` entries can't be
 /// expressed in `settings.xml` and are left to the POMs' own activation.
 pub fn configure_jdtls(cfg: &mut LanguageServerConfig, root: &Path, s: &Settings, profiles: &[String], dir: &Path) {
     if cfg.name != "jdtls" {
         return;
     }
-    let active: Vec<&str> =
-        profiles.iter().map(|p| p.trim()).filter(|p| !p.is_empty() && !p.starts_with('!')).collect();
+    let profiles = s.languages.java.maven.profiles(profiles);
+    let active: Vec<&str> = profiles.iter().map(String::as_str).filter(|p| !p.starts_with(['!', '-'])).collect();
     let Some(file) = (!active.is_empty()).then(|| write_settings(root, s, &active, dir)).flatten() else {
         remove_generated(dir, None);
         return;
@@ -192,6 +192,30 @@ mod tests {
         assert!(with_active_profiles("<settings></settings>", &["a&b"]).unwrap().contains("a&amp;b"));
     }
 
+    #[test]
+    fn jdtls_combines_settings_profiles_and_checkbox_choices() {
+        let tmp = tempfile::tempdir().unwrap();
+        let mut s = Settings::default();
+        s.languages.java.maven.user_settings = "config files/settings.xml".into();
+        s.languages.java.maven.active_profiles = " a, c, !d, a ".into();
+        std::fs::create_dir_all(tmp.path().join("config files")).unwrap();
+        std::fs::write(tmp.path().join("config files/settings.xml"), "<settings><mirrors/></settings>").unwrap();
+        let mut cfg = jdtls();
+        configure_jdtls(&mut cfg, tmp.path(), &s, &["b".into(), "!c".into(), "d".into()], &tmp.path().join("cache"));
+        let text = std::fs::read_to_string(user_settings(&cfg).unwrap()).unwrap();
+        assert!(text.contains("<mirrors/>"));
+        assert_eq!(text.matches("<activeProfile>a</activeProfile>").count(), 1);
+        assert!(text.contains("<activeProfile>b</activeProfile>"));
+        assert!(!text.contains("<activeProfile>c</activeProfile>"));
+        assert!(!text.contains("<activeProfile>d</activeProfile>"));
+
+        let mut cfg = jdtls();
+        configure_jdtls(&mut cfg, tmp.path(), &s, &[], &tmp.path().join("cache"));
+        let text = std::fs::read_to_string(user_settings(&cfg).unwrap()).unwrap();
+        assert!(text.contains("<activeProfile>a</activeProfile>"));
+        assert!(text.contains("<activeProfile>c</activeProfile>"));
+    }
+
     #[test]
     fn jdtls_imports_with_the_synced_profiles() {
         let tmp = tempfile::tempdir().unwrap();

crates/ide-sdk/src/ruby.rs

@@ -148,6 +148,28 @@ pub fn gem_bin_dirs(ruby: &Path, root: &Path) -> Vec<PathBuf> {
         .unwrap_or_default()
 }
 
+/// Prepares a Ruby debug session (rdbg) running in `dir` of the project `root`: the
+/// project Ruby's `bin` leads `env`'s `PATH` unless the configuration sets one, and the
+/// `bundle` and `rdbg` installed with that Ruby are returned by name, to start the adapter.
+pub fn debug_environment(
+    root: &Path,
+    dir: &Path,
+    s: &ide_core::settings::Settings,
+    env: &mut std::collections::BTreeMap<String, String>,
+) -> Vec<(&'static str, PathBuf)> {
+    let ruby = crate::apply::setting_path(root, &s.languages.ruby.interpreter).or_else(|| project_ruby(dir));
+    let Some((ruby, bin)) = ruby.and_then(|r| bin_dir_of(&r).map(|b| (r, b))) else { return Vec::new() };
+    env.entry("PATH".into()).or_insert_with(|| crate::exec::path_with(&[&bin]));
+    let mut gem_bins: Option<Vec<PathBuf>> = None;
+    let mut find = |name: &str| {
+        ide_core::process::find_executable(name, bin.as_os_str()).or_else(|| {
+            let dirs = gem_bins.get_or_insert_with(|| gem_bin_dirs(&ruby, dir));
+            ide_core::process::find_executable(name, &std::env::join_paths(dirs.iter()).ok()?)
+        })
+    };
+    ["bundle", "rdbg"].into_iter().filter_map(|name| Some((name, find(name)?))).collect()
+}
+
 type NamedRoots = Vec<(String, PathBuf)>;
 
 /// Standard-library / site directories (`ruby/3.3.0`) and the gems Bundler resolves
@@ -216,6 +238,40 @@ mod tests {
         assert_eq!(gems, vec![("rake-13.4.0".into(), gem), ("rspec-3.13.2".into(), external)]);
     }
 
+    #[cfg(unix)]
+    #[test]
+    fn debug_sessions_use_the_rdbg_of_the_project_ruby_and_its_path() {
+        use std::os::unix::fs::PermissionsExt;
+
+        let dir = tempfile::tempdir().unwrap();
+        let bin = dir.path().join("ruby/bin");
+        let gem_bin = dir.path().join("gems/bin");
+        for path in [&bin, &gem_bin] {
+            std::fs::create_dir_all(path).unwrap();
+        }
+        // Homebrew's Ruby installs gem executables outside its `bin`.
+        let scripts = [
+            (bin.join("ruby"), format!("#!/bin/sh\necho '{}'\n", gem_bin.display())),
+            (bin.join("bundle"), String::new()),
+            (gem_bin.join("rdbg"), String::new()),
+        ];
+        for (path, text) in scripts {
+            std::fs::write(&path, text).unwrap();
+            std::fs::set_permissions(path, std::fs::Permissions::from_mode(0o755)).unwrap();
+        }
+        let mut s = ide_core::settings::Settings::default();
+        s.languages.ruby.interpreter = bin.join("ruby").to_string_lossy().into_owned();
+
+        let mut env = std::collections::BTreeMap::new();
+        let tools = debug_environment(dir.path(), dir.path(), &s, &mut env);
+        assert_eq!(tools, [("bundle", bin.join("bundle")), ("rdbg", gem_bin.join("rdbg"))]);
+        assert_eq!(std::env::split_paths(&env["PATH"]).next(), Some(bin.clone()));
+        // The configuration's own PATH stays.
+        let mut env = std::collections::BTreeMap::from([("PATH".to_owned(), "/custom".to_owned())]);
+        debug_environment(dir.path(), dir.path(), &s, &mut env);
+        assert_eq!(env["PATH"], "/custom");
+    }
+
     #[test]
     fn parses_ruby_version_output() {
         assert_eq!(

crates/ide-sdk/src/tests.rs

@@ -343,20 +343,27 @@ fn project_jdk_and_maven_settings() {
     s.languages.java.jdk = "jdk17/bin/java".into();
     s.languages.java.maven.home = maven.to_string_lossy().into_owned();
     s.languages.java.maven.user_settings = "/m2/settings.xml".into();
+    s.languages.java.maven.toolchains = "/m2/toolchains.xml".into();
     s.languages.java.maven.local_repository = "/m2/repo".into();
     assert_eq!(project_jdk(tmp.path(), &s).map(|j| j.major), Some(17));
     assert_eq!(maven_command(tmp.path(), &s), Some(maven.join("bin/mvn")));
-    assert_eq!(maven_options(tmp.path(), &s), ["-s", "/m2/settings.xml", "-Dmaven.repo.local=/m2/repo"]);
+    assert_eq!(
+        maven_options(tmp.path(), &s),
+        ["-s", "/m2/settings.xml", "-t", "/m2/toolchains.xml", "-Dmaven.repo.local=/m2/repo"]
+    );
 
     let mut configs = vec![run("maven", "./mvnw", &["package"]), run("gradle", "./gradlew", &["build"])];
     apply_to_run_configs(&mut configs, tmp.path(), &s);
     let home = project_jdk(tmp.path(), &s).unwrap().home.to_string_lossy().into_owned();
     assert_eq!(configs[0].command, maven.join("bin/mvn").to_string_lossy());
-    assert_eq!(configs[0].args, ["-s", "/m2/settings.xml", "-Dmaven.repo.local=/m2/repo", "package"]);
+    assert_eq!(
+        configs[0].args,
+        ["-s", "/m2/settings.xml", "-t", "/m2/toolchains.xml", "-Dmaven.repo.local=/m2/repo", "package"]
+    );
     assert_eq!(configs[0].env["JAVA_HOME"], home);
     assert_eq!(configs[1].env["JAVA_HOME"], home);
     apply_to_run_configs(&mut configs, tmp.path(), &s);
-    assert_eq!(configs[0].args.len(), 4, "applied once");
+    assert_eq!(configs[0].args.len(), 6, "applied once");
 
     s.languages.java.jdk = "missing".into();
     assert_eq!(project_jdk(tmp.path(), &s), None);
@@ -448,6 +455,122 @@ fn maven_daemon_uses_the_runner_jre_version() {
     }
 }
 
+#[test]
+fn maven_options_carry_active_profiles_into_the_command_line() {
+    let tmp = tempfile::tempdir().unwrap();
+    let mut s = Settings::default();
+    s.languages.java.maven.active_profiles = "dev, integration".into();
+    assert_eq!(maven_options(tmp.path(), &s), ["-P", "dev, integration"]);
+    s.languages.java.maven.active_profiles = "  ".into();
+    assert!(maven_options(tmp.path(), &s).is_empty());
+
+    // A run configuration's own -P wins; repeated application does not duplicate the settings group.
+    s.languages.java.maven.active_profiles = "dev".into();
+    let mut configs = vec![run("maven", "./mvnw", &["package"])];
+    apply_to_run_configs(&mut configs, tmp.path(), &s);
+    assert_eq!(configs[0].args, ["-P", "dev", "package"]);
+    apply_to_run_configs(&mut configs, tmp.path(), &s);
+    assert_eq!(configs[0].args, ["-P", "dev", "package"]);
+    let mut configured = vec![run("maven", "./mvnw", &["-P", "prod", "package"])];
+    apply_to_run_configs(&mut configured, tmp.path(), &s);
+    assert_eq!(configured[0].args, ["-P", "prod", "package"]);
+}
+
+#[test]
+fn maven_profile_and_toolchain_overrides_accept_every_option_form() {
+    let tmp = tempfile::tempdir().unwrap();
+    let mut s = Settings::default();
+    s.languages.java.maven.active_profiles = "a".into();
+    s.languages.java.maven.toolchains = "config files/toolchains.xml".into();
+    let toolchains = tmp.path().join("config files/toolchains.xml").to_string_lossy().into_owned();
+    assert_eq!(maven_options(tmp.path(), &s), ["-t", &toolchains, "-P", "a"]);
+    for own in [
+        vec!["-P", "b,!c", "-t", "own file.xml"],
+        vec!["-Pb,!c", "-town file.xml"],
+        vec!["--activate-profiles", "b,!c", "--toolchains", "own file.xml"],
+        vec!["--activate-profiles=b,!c", "--toolchains=own file.xml"],
+    ] {
+        let mut args = own.clone();
+        args.push("test");
+        let mut config = run("maven", "mvn", &args);
+        config.detected = false;
+        for _ in 0..3 {
+            apply_to_run_configs(std::slice::from_mut(&mut config), tmp.path(), &s);
+            assert_eq!(config.args, args, "configuration options win: {own:?}");
+        }
+    }
+}
+
+#[test]
+fn maven_goal_profiles_combine_settings_and_checkboxes_but_keep_explicit_overrides() {
+    use crate::apply::prepare_maven_run;
+
+    let tmp = tempfile::tempdir().unwrap();
+    let mut s = Settings::default();
+    s.languages.java.maven.active_profiles = "a".into();
+    s.languages.java.maven.toolchains = "config files/toolchains.xml".into();
+    let mut config = run("maven", "mvn", &["test", "-Pb,!c"]);
+    config.id = "maven:goal:pom.xml:test".into();
+    config.detected = false;
+    let mut expected = maven_options(tmp.path(), &s);
+    expected.extend(["test".into(), "-Pb,!c".into()]);
+    for _ in 0..3 {
+        prepare_maven_run(&mut config, tmp.path(), &s);
+        assert_eq!(config.args, expected);
+        apply_to_run_configs(std::slice::from_mut(&mut config), tmp.path(), &s);
+        assert_eq!(config.args, expected);
+    }
+    s.languages.java.maven.active_profiles = "new".into();
+    prepare_maven_run(&mut config, tmp.path(), &s);
+    assert_eq!(&config.args[2..], ["-P", "new", "test", "-Pb,!c"]);
+
+    for own in
+        [vec!["-P", "prod"], vec!["-Pprod"], vec!["--activate-profiles", "prod"], vec!["--activate-profiles=prod"]]
+    {
+        let mut args = vec!["test"];
+        args.extend(own);
+        let mut config = run("maven", "mvn", &args);
+        config.id = format!("maven:goal:pom.xml:{}", args.join(" "));
+        config.detected = false;
+        for _ in 0..3 {
+            prepare_maven_run(&mut config, tmp.path(), &s);
+            assert_eq!(&config.args[2..], args);
+        }
+    }
+}
+
+#[test]
+fn maven_launch_refreshes_attached_and_long_settings_prefixes() {
+    use crate::apply::prepare_maven_run;
+
+    let tmp = tempfile::tempdir().unwrap();
+    std::fs::write(tmp.path().join("pom.xml"), "<project/>").unwrap();
+    let mut s = Settings::default();
+    s.languages.java.maven.active_profiles = "new".into();
+    s.languages.java.maven.toolchains = "new toolchains.xml".into();
+    for prefix in [
+        vec!["-told file.xml", "-Pa"],
+        vec!["--toolchains", "old file.xml", "--activate-profiles", "a"],
+        vec!["--toolchains=old file.xml", "--activate-profiles=a"],
+    ] {
+        for id in
+            ["maven:goal:pom.xml:test", "maven:test", "context:maven:test:ExampleTest", "workspace:abc:maven:test"]
+        {
+            let mut args = prefix.clone();
+            args.push("test");
+            let mut config = run("maven", "mvn", &args);
+            config.id = id.into();
+            config.detected = !id.starts_with("maven:goal:");
+            let mut expected = maven_options(tmp.path(), &s);
+            expected.push("test".into());
+            for _ in 0..3 {
+                prepare_maven_run(&mut config, tmp.path(), &s);
+                assert_eq!(config.args, expected, "{id}: {prefix:?}");
+            }
+        }
+    }
+}
+
 #[test]
 fn maven_options_carry_the_thread_count_into_the_command_line() {
     let tmp = tempfile::tempdir().unwrap();

crates/ide-search/src/lib.rs

@@ -253,6 +253,18 @@ pub fn validate_query(query: &SearchQuery) -> IdeResult<()> {
     Ok(())
 }
 
+/// Byte ranges of the matches of `query` in `text`, matched as [`search`] does.
+/// Unlike [`LineMatch`]es, a match spanning lines comes back whole.
+pub fn match_ranges(text: &str, query: &SearchQuery) -> IdeResult<Vec<(usize, usize)>> {
+    if query.pattern.is_empty() {
+        return Ok(Vec::new());
+    }
+    let compiled = query::compile(query)?;
+    let mut out = Vec::new();
+    iter::for_each_match(&compiled.matcher, text.as_bytes(), 0, |m| out.push((m.start(), m.end())));
+    Ok(out)
+}
+
 /// Computes the replacement text for every match of `query` in `text`
 /// (supports `$1` group references for regex queries).
 ///

crates/ide-tools/src/platform.rs

@@ -151,6 +151,25 @@ mod tests {
         assert_eq!(select_asset(&names, rules, WIN), Some(names[4]));
     }
 
+    #[test]
+    fn laravel_lsp_assets() {
+        let names = [
+            "server-v0.0.32-arm64-darwin",
+            "server-v0.0.32-x64-darwin",
+            "server-v0.0.32-arm64-linux",
+            "server-v0.0.32-x64-linux",
+            "server-v0.0.32-x64-win32.exe",
+        ];
+        let rules = crate::registry::find("laravel-lsp").unwrap().asset_rules();
+        assert_eq!(select_asset(&names, rules, MAC_ARM), Some(names[0]));
+        assert_eq!(select_asset(&names, rules, MAC_X64), Some(names[1]));
+        assert_eq!(select_asset(&names, rules, LINUX_ARM), Some(names[2]));
+        assert_eq!(select_asset(&names, rules, LINUX_X64), Some(names[3]));
+        assert_eq!(select_asset(&names, rules, WIN), Some(names[4]));
+        // The composer-installed helper is not a release asset.
+        assert_eq!(select_asset(&["laravel-lsp"], rules, LINUX_X64), None);
+    }
+
     #[test]
     fn kmp_lsp_assets_include_the_native_jar_indexer() {
         let names = [

crates/ide-tools/src/registry.rs

@@ -396,6 +396,35 @@ pub static TOOLS: &[ToolSpec] = &[
         homepage: "https://intelephense.com",
         needs: &[],
     },
+    ToolSpec {
+        name: "laravel-lsp",
+        display: "Laravel LSP",
+        kind: LanguageServer,
+        commands: &["laravel-lsp"],
+        // Plain binaries per platform (`server-v*-<arch>-<os>[.exe]`).
+        method: Method::Release {
+            source: ReleaseSource::GitHub { repo: "laravel/lsp" },
+            assets: &[
+                rule(Mac, Arm64, "server-v*-arm64-darwin"),
+                rule(Mac, X64, "server-v*-x64-darwin"),
+                rule(Linux, Arm64, "server-v*-arm64-linux"),
+                rule(Linux, X64, "server-v*-x64-linux"),
+                rule(Windows, X64, "server-v*-x64-win32.exe"),
+            ],
+            locate: &[
+                "laravel-lsp",
+                "server-v*-arm64-darwin",
+                "server-v*-x64-darwin",
+                "server-v*-arm64-linux",
+                "server-v*-x64-linux",
+                "server-v*-x64-win32",
+            ],
+        },
+        fallback: None,
+        version: ver("laravel-lsp"),
+        homepage: "https://github.com/laravel/lsp",
+        needs: &[],
+    },
     ToolSpec {
         name: "gopls",
         display: "gopls",

crates/ide-workspace/src/lib.rs

@@ -12,6 +12,7 @@ pub mod file_refs;
 pub mod history;
 pub mod memory;
 pub mod process;
+pub mod project_discovery;
 pub mod recent;
 pub mod roots;
 pub mod settings;

crates/ide-workspace/src/project_discovery.rs

@@ -0,0 +1,247 @@
+//! Bounded discovery of independent projects selected through the workspace folder picker.
+
+use ide_core::{CancellationToken, IdeError, IdeResult, IpcPath};
+use serde::{Deserialize, Serialize};
+use std::collections::{HashSet, VecDeque};
+use std::path::{Path, PathBuf};
+
+const MAX_DEPTH: usize = 4;
+const MAX_ENTRIES: usize = 20_000;
+const SKIP_DIRS: &[&str] = &["node_modules", "target", "build", "dist", "vendor", ".venv", ".git"];
+
+#[derive(Debug, Serialize, Deserialize, specta::Type)]
+pub struct DiscoveredProject {
+    pub path: IpcPath,
+    pub root: IpcPath,
+    pub relative_path: String,
+}
+
+#[derive(Debug, Default, Serialize, Deserialize, specta::Type)]
+pub struct ProjectDiscovery {
+    /// Selected projects and folders with no discovered projects retain the direct-add behaviour.
+    pub direct: Vec<IpcPath>,
+    pub projects: Vec<DiscoveredProject>,
+    pub truncated: bool,
+}
+
+fn check_cancel(cancel: &CancellationToken) -> IdeResult<()> {
+    if cancel.is_cancelled() { Err(IdeError::cancelled()) } else { Ok(()) }
+}
+
+fn is_project(dir: &Path, cancel: &CancellationToken) -> IdeResult<bool> {
+    for marker in crate::roots::BUILD_FILES.iter().chain([".git", ".idea", "CMakeLists.txt"].iter()) {
+        check_cancel(cancel)?;
+        if std::fs::symlink_metadata(dir.join(marker))
+            .is_ok_and(|m| m.is_file() || matches!(*marker, ".git" | ".idea") && m.is_dir())
+        {
+            return Ok(true);
+        }
+    }
+    Ok(false)
+}
+
+/// Does not follow symlinks or descend into a project. The entry budget spans all selected folders.
+pub fn discover(folders: Vec<PathBuf>, cancel: &CancellationToken) -> IdeResult<ProjectDiscovery> {
+    discover_with_limit(folders, cancel, MAX_ENTRIES)
+}
+
+fn discover_with_limit(
+    folders: Vec<PathBuf>,
+    cancel: &CancellationToken,
+    mut remaining: usize,
+) -> IdeResult<ProjectDiscovery> {
+    let mut result = ProjectDiscovery::default();
+    let mut seen_roots = HashSet::new();
+    let mut seen_projects = HashSet::new();
+    for root in folders {
+        check_cancel(cancel)?;
+        if !seen_roots.insert(root.clone()) {
+            continue;
+        }
+        let metadata = std::fs::symlink_metadata(&root)?;
+        // A link explicitly selected by the picker may still be added, but never traversed.
+        if metadata.is_symlink() || is_project(&root, cancel)? {
+            result.direct.push(root.into());
+            continue;
+        }
+        if !metadata.is_dir() {
+            return Err(IdeError::invalid("Choose a project folder"));
+        }
+        let mut found = false;
+        let mut queue = VecDeque::from([(root.clone(), 0)]);
+        while let Some((dir, depth)) = queue.pop_front() {
+            check_cancel(cancel)?;
+            if depth > 0 && is_project(&dir, cancel)? {
+                found = true;
+                if seen_projects.insert(dir.clone()) {
+                    result.projects.push(DiscoveredProject {
+                        relative_path: ide_core::ipc_path::to_ipc(dir.strip_prefix(&root).unwrap()),
+                        path: dir.into(),
+                        root: root.clone().into(),
+                    });
+                }
+                continue;
+            }
+            if depth == MAX_DEPTH {
+                continue;
+            }
+            if remaining == 0 {
+                result.truncated = true;
+                continue;
+            }
+            let entries = match std::fs::read_dir(&dir) {
+                Ok(entries) => entries,
+                Err(error) if depth == 0 => return Err(error.into()),
+                Err(_) => continue,
+            };
+            let mut children = Vec::new();
+            for entry in entries {
+                check_cancel(cancel)?;
+                if remaining == 0 {
+                    result.truncated = true;
+                    break;
+                }
+                remaining -= 1;
+                let Ok(entry) = entry else { continue };
+                let name = entry.file_name();
+                let name = name.to_string_lossy();
+                if name.starts_with('.') || SKIP_DIRS.contains(&name.as_ref()) {
+                    continue;
+                }
+                if entry.file_type().is_ok_and(|kind| kind.is_dir()) {
+                    children.push(entry.path());
+                }
+            }
+            children.sort();
+            queue.extend(children.into_iter().map(|path| (path, depth + 1)));
+        }
+        if !found {
+            result.direct.push(root.into());
+        }
+    }
+    check_cancel(cancel)?;
+    Ok(result)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::fs;
+
+    fn project(root: &Path, relative: &str, marker: &str) -> PathBuf {
+        let dir = root.join(relative);
+        fs::create_dir_all(&dir).unwrap();
+        if marker == ".idea" || marker == ".git" {
+            fs::create_dir(dir.join(marker)).unwrap();
+        } else {
+            fs::write(dir.join(marker), "").unwrap();
+        }
+        dir
+    }
+
+    #[test]
+    fn detects_shared_build_files_and_workspace_markers_without_descending() {
+        for marker in crate::roots::BUILD_FILES.iter().chain([".git", ".idea", "CMakeLists.txt"].iter()) {
+            let tmp = tempfile::tempdir().unwrap();
+            let parent = project(tmp.path(), "app", marker);
+            project(&parent, "module", "package.json");
+            let result = discover(vec![tmp.path().into()], &CancellationToken::new()).unwrap();
+            assert!(result.direct.is_empty(), "{marker}");
+            assert_eq!(result.projects.len(), 1, "{marker}");
+            assert_eq!(result.projects[0].path, parent);
+            assert_eq!(result.projects[0].relative_path, "app");
+            let direct = discover(vec![parent.clone()], &CancellationToken::new()).unwrap();
+            assert_eq!(direct.direct[0], parent);
+            assert!(direct.projects.is_empty());
+        }
+    }
+
+    #[test]
+    fn skips_dependencies_outputs_and_hidden_directories() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        // .git is itself a marker, so test it below a hidden directory.
+        for skip in SKIP_DIRS.iter().filter(|name| **name != ".git").chain([&".hidden"]) {
+            project(root, &format!("{skip}/app"), "Cargo.toml");
+        }
+        project(root, ".hidden/.git/app", "go.mod");
+        let result = discover(vec![root.into()], &CancellationToken::new()).unwrap();
+        assert!(result.projects.is_empty());
+        assert_eq!(result.direct[0], root);
+    }
+
+    #[test]
+    fn finds_depth_four_but_not_five_and_retains_empty_folders() {
+        let tmp = tempfile::tempdir().unwrap();
+        let expected = project(tmp.path(), "a/b/c/app", "pom.xml");
+        project(tmp.path(), "deep/b/c/d/app", "package.json");
+        let empty = tmp.path().join("empty");
+        fs::create_dir(&empty).unwrap();
+        let result = discover(vec![tmp.path().into(), empty.clone()], &CancellationToken::new()).unwrap();
+        assert_eq!(result.projects.len(), 1);
+        assert_eq!(result.projects[0].path, expected);
+        assert_eq!(result.direct[0], empty);
+    }
+
+    #[test]
+    fn deduplicates_overlapping_selections_and_shares_the_entry_budget() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        project(root, "a/app", "go.mod");
+        let result = discover(vec![root.into(), root.join("a"), root.into()], &CancellationToken::new()).unwrap();
+        assert_eq!(result.projects.len(), 1);
+        assert!(result.direct.is_empty());
+        let result = discover_with_limit(vec![root.into(), root.join("a")], &CancellationToken::new(), 1).unwrap();
+        assert!(result.truncated);
+        assert!(result.projects.is_empty());
+    }
+
+    #[test]
+    fn cancellation_also_stops_direct_adds() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = project(tmp.path(), "app", "Cargo.toml");
+        let cancel = CancellationToken::new();
+        cancel.cancel();
+        let error = discover(vec![root], &cancel).unwrap_err();
+        assert_eq!(error.kind, ide_core::error::ErrorKind::Cancelled);
+    }
+
+    #[test]
+    fn git_worktree_files_are_project_markers() {
+        let tmp = tempfile::tempdir().unwrap();
+        fs::write(tmp.path().join(".git"), "gitdir: ../main/.git/worktrees/app").unwrap();
+        let result = discover(vec![tmp.path().into()], &CancellationToken::new()).unwrap();
+        assert_eq!(result.direct[0], tmp.path().to_path_buf());
+        assert!(result.projects.is_empty());
+    }
+
+    #[test]
+    fn reports_truncation_and_keeps_projects_found_before_the_limit() {
+        let tmp = tempfile::tempdir().unwrap();
+        let first = tmp.path().join("first");
+        let expected = project(&first, "app", "Cargo.toml");
+        let second = tmp.path().join("second");
+        project(&second, "app", "package.json");
+        let result = discover_with_limit(vec![first, second.clone()], &CancellationToken::new(), 1).unwrap();
+        assert!(result.truncated);
+        assert_eq!(result.projects.len(), 1);
+        assert_eq!(result.projects[0].path, expected);
+        assert_eq!(result.direct[0], second);
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn never_follows_symlink_loops_or_linked_projects_or_markers() {
+        use std::os::unix::fs::symlink;
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path().join("container");
+        fs::create_dir(&root).unwrap();
+        let external = project(tmp.path(), "outside", "package.json");
+        symlink(&root, root.join("loop")).unwrap();
+        symlink(&external, root.join("linked")).unwrap();
+        symlink(external.join("package.json"), root.join("package.json")).unwrap();
+        let result = discover(vec![root.clone()], &CancellationToken::new()).unwrap();
+        assert!(result.projects.is_empty());
+        assert_eq!(result.direct[0], root);
+    }
+}

crates/ide-workspace/src/roots/detect.rs

@@ -18,7 +18,7 @@ const SKIP_DIRS: &[&str] =
     &["node_modules", "target", "build", "dist", "out", "venv", "__pycache__", "vendor", "bower_components"];
 
 /// Build files whose changes can change the detected roots.
-const BUILD_FILES: &[&str] = &[
+pub(crate) const BUILD_FILES: &[&str] = &[
     "pom.xml",
     "build.gradle",
     "build.gradle.kts",

crates/ide-workspace/src/roots/mod.rs

@@ -6,6 +6,7 @@
 //! project-relative and `/`-separated; `""` is the project root itself.
 
 mod detect;
+pub(crate) use detect::BUILD_FILES;
 mod gradle;
 mod java;
 mod maven;

crates/ide-workspace/src/settings.rs

@@ -27,7 +27,10 @@ pub enum SettingsScope {
     Project,
 }
 
-fn remove_custom_schemes(layer: &mut Json) {
+fn remove_global_settings(layer: &mut Json) {
+    if let Some(layer) = layer.as_object_mut() {
+        layer.remove("mcpServer");
+    }
     if let Some(editor) = layer.get_mut("editor").and_then(Json::as_object_mut) {
         editor.remove("customSchemes");
     }
@@ -187,7 +190,7 @@ impl SettingsStore {
         for (scope, file) in self.layers() {
             let Some(mut layer) = read_layer(&file) else { continue };
             if scope == SettingsScope::Project {
-                remove_custom_schemes(&mut layer);
+                remove_global_settings(&mut layer);
             }
             if let Err(e) = try_merge(&mut merged, layer) {
                 tracing::warn!("{} has invalid settings, ignoring it: {e}", file.display());
@@ -220,6 +223,9 @@ impl SettingsStore {
         {
             return Err(IdeError::invalid("custom color schemes belong to user settings"));
         }
+        if scope == SettingsScope::Project && (key == "mcpServer" || key.starts_with("mcpServer.")) {
+            return Err(IdeError::invalid("MCP server belongs to user settings"));
+        }
         let file = self.file(scope).ok_or_else(|| IdeError::invalid("no project is open"))?.to_path_buf();
         let segments: Vec<&str> = key.split('.').collect();
         if segments.iter().any(|s| s.is_empty()) {
@@ -259,7 +265,7 @@ impl SettingsStore {
             let layer = if is_target { parse_layer(&new_text).ok() } else { read_layer(&layer_file) };
             let Some(mut layer) = layer else { continue };
             if layer_scope == SettingsScope::Project {
-                remove_custom_schemes(&mut layer);
+                remove_global_settings(&mut layer);
             }
             if let Err(e) = try_merge(&mut merged, layer)
                 && is_target
@@ -637,4 +643,22 @@ mod tests {
         let s = store.set(SettingsScope::Global, "appearance.mainToolbar", Json::Null).unwrap();
         assert_eq!(s.appearance.main_toolbar, None);
     }
+    #[test]
+    fn mcp_server_is_default_off_and_cannot_be_enabled_by_a_project() {
+        let tmp = tempfile::tempdir().unwrap();
+        let config = tmp.path().join("config");
+        let project = tmp.path().join("project");
+        std::fs::create_dir_all(project.join(".openidea")).unwrap();
+        std::fs::write(project.join(".openidea/settings.toml"), "[mcpServer]\nenabled = true\n").unwrap();
+        let settings = SettingsStore::load(&config, Some(&project));
+        assert!(!settings.effective().mcp_server.enabled);
+        assert!(settings.set(SettingsScope::Project, "mcpServer.enabled", serde_json::json!(true)).is_err());
+        assert!(
+            settings
+                .set(SettingsScope::Global, "mcpServer.enabled", serde_json::json!(true))
+                .unwrap()
+                .mcp_server
+                .enabled
+        );
+    }
 }

docs/command-line.md

@@ -0,0 +1,41 @@
+# Command-line launcher
+
+Install the `openidea` command from **OpenIDEA → Install 'openidea' Command** on
+macOS, or **Tools → Install 'openidea' Command** on Windows and Linux. The same
+action is available in Find Action. Open a new terminal after installation.
+
+- **macOS:** move OpenIDEA to Applications first. The command links to the launcher
+  inside the app bundle. It uses `~/.local/bin` when that directory is on PATH;
+  otherwise it uses `/usr/local/bin` and may request an administrator password.
+- **Windows:** installation creates `openidea.cmd` in
+  `%LOCALAPPDATA%\OpenIDEA\bin` and adds that directory to the user PATH. This
+  works with installed and portable copies, without administrator rights.
+- **Linux:** installation creates `~/.local/bin/openidea`. If another command
+  takes precedence or this directory is absent from PATH, the notification asks
+  you to put it at the beginning of your shell's PATH. For Bash and Zsh, add
+  `export PATH="$HOME/.local/bin:$PATH"` to your shell profile. For Fish, run
+  `fish_add_path --prepend ~/.local/bin`. An AppImage launcher targets the original
+  AppImage; keep that file in a permanent location.
+
+```sh
+openidea .
+openidea src/main.rs README.md
+openidea --line 12 --column 5 src/main.rs
+openidea src/main.rs:12:5
+openidea diff before.txt after.txt
+openidea --help
+openidea --version
+```
+
+Folders open as projects. Files open in their project's window, or in LightEdit
+when no project contains them. Lines and columns start at 1. With no paths, the
+command focuses OpenIDEA. It starts the app if necessary and returns after handing
+off the request. Unknown options and missing files exit with code 1.
+
+Use `--` before a filename beginning with `-`, or before a file named `diff`.
+The existing GUI executable and OS file associations still work.
+
+**Uninstall 'openidea' Command** removes only OpenIDEA's launcher, and on Windows
+its dedicated user PATH entry. A command belonging to another application is
+never overwritten or removed. Reinstall the command after moving a portable
+copy or AppImage to a different location.

docs/plugins/themes.md

@@ -103,6 +103,10 @@ Three things still layer on top of it:
 The selection is remembered. When the plugin is disabled or uninstalled the
 built-in theme returns.
 
+Stripe tooltips use `--bg-stripe-tooltip`, `--fg-stripe-tooltip`,
+`--border-stripe-tooltip` and `--shadow-stripe-tooltip`. A plugin that omits
+these tokens inherits its corresponding base tooltip tokens, including in light themes.
+
 ## Building, packaging, installing
 
 There is no build step. The package *is* the folder.
@@ -324,7 +328,7 @@ a token.
 
 <!-- BEGIN GENERATED TOKEN REFERENCE: pnpm gen:theme-docs -->
 
-242 themeable tokens: 121 in the UI theme file, 121 in the editor colour scheme file.
+247 themeable tokens: 125 in the UI theme file, 122 in the editor colour scheme file.
 
 ### Surfaces (UI theme)
 
@@ -431,6 +435,7 @@ a token.
 | `--syn-punct` | `#bcbec4` | `#080808` |
 | `--syn-variable` | `#bcbec4` | `#080808` |
 | `--syn-global` | `var(--syn-variable)` | `var(--syn-variable)` |
+| `--syn-namespace` | `var(--fg-editor)` | `var(--fg-editor)` |
 | `--syn-param` | `#bcbec4` | `#080808` |
 | `--syn-property` | `#c77dbb` | `#871094` |
 | `--syn-constant` | `#c77dbb` | `#871094` |
@@ -570,6 +575,10 @@ a token.
 
 | Token | Islands Dark | Islands Light |
 |---|---|---|
+| `--bg-stripe-tooltip` | `var(--bg-tooltip)` | `#27282e` |
+| `--fg-stripe-tooltip` | `var(--fg-tooltip)` | `#ffffff` |
+| `--border-stripe-tooltip` | `var(--border-tooltip)` | `#383a42` |
+| `--shadow-stripe-tooltip` | `var(--shadow-tooltip)` | `0 2px 8px rgba(0, 0, 0, 0.24)` |
 | `--bg-tooltip` | `#33353b` | `#ffffff` |
 | `--fg-tooltip` | `#d1d3d9` | `#000000` |
 | `--border-tooltip` | `#33353b` | `#d1d3d9` |

e2e/agentApproval.spec.ts

@@ -112,9 +112,10 @@ for (const theme of ["dark", "light"] as const) {
       });
       expect(geometry.scroll).toBe(geometry.client);
       expect(geometry.contained).toBe(true);
-      expect(geometry.promptRadius).toBeLessThanOrEqual(4);
-      expect(geometry.replyBackground).not.toBe("rgba(0, 0, 0, 0)");
-      expect(geometry.replyBorder).toBe("1px");
+      expect(geometry.promptRadius).toBeLessThanOrEqual(6);
+      // Replies read as plain text on the panel.
+      expect(geometry.replyBackground).toBe("rgba(0, 0, 0, 0)");
+      expect(geometry.replyBorder).toBe("0px");
       expect(geometry.userOnRight).toBe(true);
       expect(geometry.approvalAligned).toBe(true);
       expect(geometry.authorBeforeWork).toBe(true);

e2e/boot.spec.ts

@@ -0,0 +1,89 @@
+import { expect, test } from "@playwright/test";
+
+test("a module evaluation failure replaces the splash with copyable details", async ({ page }) => {
+  await page.route("**/src/main.tsx", (route) =>
+    route.fulfill({ contentType: "text/javascript", body: 'throw new Error("Simulated startup failure");' }),
+  );
+  await page.goto("/");
+  await expect(page.getByRole("heading", { name: "OpenIDEA could not start" })).toBeVisible();
+  await expect(page.locator("#splash")).toHaveCount(0);
+  await expect(page.getByRole("textbox", { name: "Startup error details" })).toHaveValue(/Simulated startup failure/);
+  await expect(page.getByRole("button", { name: "Copy details" })).toBeFocused();
+  await expect(page.getByRole("link", { name: "Report an issue" })).toHaveAttribute("href", /github.com/);
+});
+
+test("an unresolved module gets a startup timeout", async ({ page }) => {
+  await page.clock.install();
+  await page.route("**/src/main.tsx", (route) =>
+    route.fulfill({ contentType: "text/javascript", body: "await new Promise(() => {});" }),
+  );
+  await page.goto("/", { waitUntil: "commit" });
+  await page.locator("#splash").waitFor({ state: "attached" });
+  await page.clock.runFor(30_000);
+  await expect(page.getByRole("textbox", { name: "Startup error details" })).toHaveValue(
+    /Startup did not finish within 30 seconds/,
+  );
+});
+
+test("a rejected boot shows Chinese diagnostics without application modules", async ({ browser }) => {
+  const context = await browser.newContext({ locale: "zh-CN" });
+  const page = await context.newPage();
+  try {
+    await context.route("https://github.com/**", (route) =>
+      route.fulfill({ contentType: "text/html", body: "Issue report destination" }),
+    );
+    await page.route("**/src/main.tsx", (route) =>
+      route.fulfill({ contentType: "text/javascript", body: 'await Promise.reject(new Error("Boot rejected"));' }),
+    );
+    await page.goto("/");
+    await expect(page.getByRole("heading", { name: "OpenIDEA 无法启动" })).toBeVisible();
+    await expect(page.getByRole("textbox", { name: "启动错误详情" })).toHaveValue(/Boot rejected/);
+    await page.evaluate(() => {
+      Object.defineProperty(navigator, "clipboard", {
+        value: { writeText: async (value: string) => sessionStorage.setItem("copied-diagnostics", value) },
+      });
+    });
+    await page.getByRole("button", { name: "复制详情" }).click();
+    await expect(page.getByRole("status")).toHaveText("已复制");
+    expect(await page.evaluate(() => sessionStorage.getItem("copied-diagnostics"))).toContain("Boot rejected");
+    const popup = page.waitForEvent("popup");
+    await page.getByRole("link", { name: "报告问题" }).click();
+    await expect(await popup).toHaveURL("https://github.com/l0ng-ai/openidea/issues/new?template=bug_report.yml");
+  } finally {
+    await context.close();
+  }
+});
+
+test("a slow module load succeeds before the deadline and cancels the startup timer", async ({ page }) => {
+  await page.clock.install();
+  await page.addInitScript(() => {
+    new MutationObserver((records) => {
+      if (
+        records.some((record) =>
+          [...record.addedNodes].some((node) => node instanceof Element && node.id === "boot-error"),
+        )
+      )
+        sessionStorage.setItem("boot-error-seen", "true");
+    }).observe(document, { childList: true, subtree: true });
+  });
+  let release!: () => void;
+  const gate = new Promise<void>((resolve) => (release = resolve));
+  await page.route("**/src/main.tsx", async (route) => {
+    const response = await route.fetch();
+    await gate;
+    await route.fulfill({ response });
+  });
+  const moduleRequest = page.waitForRequest("**/src/main.tsx");
+  await page.goto("/", { waitUntil: "commit" });
+  await moduleRequest;
+  await page.locator("#splash").waitFor({ state: "attached" });
+  await page.clock.runFor(15_000);
+  await expect(page.locator("#boot-error")).toHaveCount(0);
+  release();
+  await expect(page.locator("#root")).not.toBeEmpty();
+  await page.clock.runFor(4000);
+  await expect(page.locator("#splash")).toHaveCount(0);
+  await page.clock.runFor(35_000);
+  await expect(page.locator("#boot-error")).toHaveCount(0);
+  expect(await page.evaluate(() => sessionStorage.getItem("boot-error-seen"))).toBeNull();
+});

e2e/commentToggle.spec.ts

@@ -0,0 +1,32 @@
+import { expect, openFromTree, test } from "./fixtures";
+
+// A JSX comment is `{/* … */}` among JSX children, while its own text parses as
+// JavaScript, where the tokens are `/* … */`. Toggling must still take it back out.
+const SRC = `export function App() {
+  return (
+    <div>
+      <b>x</b>
+    </div>
+  );
+}
+`;
+
+test("⌘/ twice on a JSX line gives the line back", async ({ workbench: page }) => {
+  await page.evaluate(async (src) => {
+    const backendModule = "/src/editor/core/backend.ts";
+    const mod = await import(/* @vite-ignore */ backendModule);
+    const backend = mod.docBackend() as { files: Map<string, string> };
+    backend.files.set("/dev/acme-api/App.tsx", src);
+  }, SRC);
+
+  const editor = await openFromTree(page, "App.tsx");
+  const content = editor.locator(".cm-content");
+  await editor.locator(".cm-line", { hasText: "<b>x</b>" }).click();
+
+  await page.keyboard.press("Meta+/");
+  await expect(content).toContainText("{/* <b>x</b> */}");
+
+  await page.keyboard.press("Meta+/");
+  await expect(content).not.toContainText("/*");
+  await expect(editor.locator(".cm-line", { hasText: "<b>x</b>" })).toHaveText("<b>x</b>");
+});

e2e/compactSettingsControls.spec.ts

@@ -0,0 +1,59 @@
+import { expect, test } from "./fixtures";
+
+for (const [id, selector] of [
+  ["general", "[class*='radios'] label"],
+  ["notifications", "table tbody td:first-child"],
+  ["keymap", "[class*='presetLabel']"],
+  ["editor.inspections", "[class*='profileRow'] > span:first-child"],
+  ["vcs.issueNavigation", "[class*='pageBody'] button:not([aria-label])"],
+]) {
+  test(`${id} keeps compact labels inside their controls`, async ({ workbench: page }) => {
+    await page.keyboard.press("Meta+,");
+    const dialog = page.getByRole("dialog");
+    await expect(dialog).toBeVisible();
+    await page.evaluate(async (id) => {
+      const localePath = "/src/platform/i18n.ts";
+      await (await import(/* @vite-ignore */ localePath)).setLocale("zh");
+      const stagingPath = "/src/features/settings/model/staging.ts";
+      (await import(/* @vite-ignore */ stagingPath)).selectPage(id);
+    }, id);
+    const labels = dialog.locator(selector);
+    await expect(labels.first()).toBeVisible();
+    for (const width of [1000, 640, 520]) {
+      await page.setViewportSize({ width, height: 760 });
+      const fits = await labels.evaluateAll((labels) =>
+        labels.every((label) => {
+          const box = label.getBoundingClientRect();
+          const range = document.createRange();
+          range.selectNodeContents(label);
+          const lines = [...range.getClientRects()].filter((r) => r.width > 0 && r.height > 0);
+          return (
+            lines.every((r) => r.left >= box.left - 1 && r.right <= box.right + 1 && r.height <= 24) &&
+            Math.max(...lines.map((r) => r.bottom)) - Math.min(...lines.map((r) => r.top)) <= 24
+          );
+        }),
+      );
+      expect(fits).toBe(true);
+    }
+  });
+}
+
+for (const [id, selector] of [
+  ["general", "[class*='fontRow'] > label"],
+  ["build.console", "[class*='inlineRow'] > label"],
+]) {
+  test(`${id} keeps a readable width for inline text`, async ({ workbench: page }) => {
+    await page.keyboard.press("Meta+,");
+    await expect(page.getByRole("dialog", { name: "Settings", exact: true })).toBeVisible();
+    await page.evaluate(async (id) => {
+      const localePath = "/src/platform/i18n.ts";
+      await (await import(/* @vite-ignore */ localePath)).setLocale("zh");
+      const path = "/src/features/settings/model/staging.ts";
+      (await import(/* @vite-ignore */ path)).selectPage(id);
+    }, id);
+    const text = page.locator(selector).first();
+    await expect(text).toBeVisible();
+    await page.setViewportSize({ width: 520, height: 760 });
+    expect((await text.boundingBox())!.width).toBeGreaterThan(100);
+  });
+}

e2e/databaseDialogLayout.spec.ts

@@ -0,0 +1,34 @@
+import { expect, test } from "./fixtures";
+
+for (const kind of ["password", "sshSecret", "params"] as const) {
+  test(`database ${kind} dialog keeps its fields inside the window`, async ({ workbench: page }) => {
+    await page.evaluate(async (kind) => {
+      const path = "/src/features/database/store.ts";
+      const { openDialog } = await import(/* @vite-ignore */ path);
+      const source = {
+        id: "layout-test",
+        name: "Layout test",
+        driver: "postgres",
+        user: "account_".repeat(30),
+        ssh: { enabled: true, host: "bastion.example.invalid", auth: "password" },
+      };
+      if (kind === "password") openDialog({ kind, source, resolve: () => {} });
+      else if (kind === "sshSecret")
+        openDialog({ kind, source, prompt: "SSH password required for " + "host_".repeat(30), resolve: () => {} });
+      else openDialog({ kind, names: ["parameter_".repeat(25)], resolve: () => {} });
+    }, kind);
+    const dialog = page.getByRole("dialog");
+    await expect(dialog).toBeVisible();
+    for (const width of [1000, 640, 500]) {
+      await page.setViewportSize({ width, height: 760 });
+      const fits = await dialog.evaluate((dialog) => {
+        const box = dialog.getBoundingClientRect();
+        return [...dialog.querySelectorAll("input, [class*='form_']")].every((el) => {
+          const r = el.getBoundingClientRect();
+          return r.left >= box.left && r.right <= box.right && el.scrollWidth <= el.clientWidth + 1;
+        });
+      });
+      expect(fits).toBe(true);
+    }
+  });
+}

e2e/diff-navigation.spec.ts

@@ -56,10 +56,7 @@ test("skips binary and unchanged siblings and restores after changing preview fi
   const toolbar = await openChain(page);
   await page.evaluate(async () => {
     const inputPath = "/src/features/vcs/diffInput.ts";
-    const layoutPath = "/src/workbench/toolwindows/store.ts";
     const { openDiff, withChain } = await import(inputPath);
-    const { useToolWindowLayout } = await import(layoutPath);
-    useToolWindowLayout.setState({ maximized: "left" });
     const files = [
       ["a.ts", "after\n"],
       ["binary.dat", "\0binary"],
@@ -73,7 +70,13 @@ test("skips binary and unchanged siblings and restores after changing preview fi
     await openDiff(withChain(files, 0), { preview: true });
   });
   await expect(toolbar).toContainText("1 difference");
-  await toolbar.getByRole("button", { name: "Maximize Editor", exact: true }).click();
+  await page.evaluate(async () => {
+    const layoutPath = "/src/workbench/toolwindows/store.ts";
+    const { useToolWindowLayout, hideAllToolWindows } = await import(layoutPath);
+    useToolWindowLayout.setState({ maximized: "left" });
+    hideAllToolWindows();
+  });
+  await toolbar.locator("..").locator(".cm-content").last().focus();
   const selected = page.getByRole("tablist", { name: "Editor tabs" }).locator('[aria-selected="true"]');
   await page.keyboard.press("F7");
   await page.keyboard.press("F7");
@@ -90,5 +93,6 @@ test("skips binary and unchanged siblings and restores after changing preview fi
     return (await import(layoutPath)).useToolWindowLayout.getState().maximized;
   });
   expect(maximized).toBe("left");
+  await expect(toolbar).toBeHidden();
   await expect(page.getByRole("tree", { name: "Project", exact: true })).toBeVisible();
 });

e2e/diff.spec.ts

@@ -294,18 +294,19 @@ test.describe("10,000-line files", () => {
       await page.keyboard.press("Meta+ArrowUp");
       await page.keyboard.press("F7");
       await expect(counter(page)).toHaveText("1 of 42 differences");
-      const first = await rendered(page);
       if (opts.mode !== "unified") {
-        expect(first.a.words).toContainEqual(["compute", "modified"]);
-        expect(first.b.words).toContainEqual(["computeFast", "modified"]);
+        await expect.poll(async () => (await rendered(page)).a.words).toContainEqual(["compute", "modified"]);
+        await expect.poll(async () => (await rendered(page)).b.words).toContainEqual(["computeFast", "modified"]);
       }
       // The last difference is reachable and still highlighted.
       await page.keyboard.press("Meta+ArrowDown");
       await page.keyboard.press("Shift+F7");
       await expect(counter(page)).toHaveText("42 of 42 differences");
-      const last = await rendered(page);
-      if (opts.mode === "unified") expect(last.b.lines).toContain("inserted");
-      else expect(last.b.words).toContainEqual(["computeFast", "modified"]);
+      if (opts.mode === "unified") {
+        await expect.poll(async () => (await rendered(page)).b.lines).toContain("inserted");
+      } else {
+        await expect.poll(async () => (await rendered(page)).b.words).toContainEqual(["computeFast", "modified"]);
+      }
       await scrollToEnd(page);
       if (opts.mode !== "unified") {
         const [a, b] = await topLines(page);