fix(i18n): translate the GitHub pull request operations' progress and failure titles

The GitHub tool window's long operations (checking out a pull request,
fetching it for a diff, creating its worktree, applying or committing a
suggested change, resolving a thread) passed their banner title as an
untagged string, and the failure notification appended " failed" to it, so
the banner stayed English and the error read "Checking out #12失败". Each
operation now names a translated progress title and its own failure title.

.github/workflows/ci.yml

@@ -71,6 +71,57 @@ jobs:
       - run: cargo build --locked -p ide-host --bin openidea-server --target x86_64-unknown-linux-musl
       - run: target/x86_64-unknown-linux-musl/debug/openidea-server --version
 
+  # The plugin SDK, the official plugins and the test fixtures build in their
+  # own workspaces (the root excludes them), so the jobs above don't see them.
+  plugins:
+    name: Plugins (SDK, official, fixtures)
+    runs-on: ubuntu-22.04
+    env:
+      CARGO_TARGET_DIR: ${{ github.workspace }}/target-plugins
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with: { targets: wasm32-wasip2, components: "clippy, rustfmt" }
+      - uses: Swatinem/rust-cache@v2
+        with:
+          key: plugins
+          cache-directories: target-plugins
+          save-if: ${{ github.ref == 'refs/heads/main' }}
+      - name: Format, lint (host and wasm) and test each crate
+        shell: bash
+        run: |
+          set -euo pipefail
+          for dir in sdk/rust/openidea-plugin plugins/official/*/ crates/ide-plugin/tests/fixtures/*/; do
+            [ -f "$dir/Cargo.toml" ] || continue
+            echo "::group::$dir"
+            cargo fmt --check --manifest-path "$dir/Cargo.toml"
+            cargo clippy --locked --all-targets --manifest-path "$dir/Cargo.toml" -- -D warnings
+            cargo clippy --locked --target wasm32-wasip2 --manifest-path "$dir/Cargo.toml" -- -D warnings
+            cargo test --locked --manifest-path "$dir/Cargo.toml"
+            echo "::endgroup::"
+          done
+      - uses: pnpm/action-setup@v4
+        with: { version: 11 }
+      - uses: actions/setup-node@v4
+        with: { node-version: 22 }
+      # Plugin web pages (`web-src/`, their own pnpm projects): typecheck and test.
+      - name: Web pages typecheck and test
+        shell: bash
+        run: |
+          set -euo pipefail
+          for dir in plugins/official/*/web-src/; do
+            [ -f "$dir/package.json" ] || continue
+            echo "::group::$dir"
+            pnpm --dir "$dir" install --frozen-lockfile --ignore-workspace
+            pnpm --dir "$dir" exec tsc --noEmit
+            pnpm --dir "$dir" test
+            echo "::endgroup::"
+          done
+      # The host's tests run the checked-in components: they must be built from these sources.
+      # Web pages aren't checked in: this builds them and checks the result.
+      - name: Checked-in components are up to date, web pages build
+        run: plugins/build.sh --check
+
   deny:
     name: Cargo deny
     runs-on: ubuntu-latest

.github/workflows/release.yml

@@ -180,6 +180,69 @@ jobs:
           if command -v sha256sum >/dev/null; then sha256sum "$ASSET"; else shasum -a 256 "$ASSET"; fi > "$ASSET.sha256"
           gh release upload "$TAG" "$ASSET" "$ASSET.sha256" --clobber
 
+  # The official plugins, signed, and the marketplace index released apps read
+  # (releases/latest/download/plugins-index.json). They are not in the
+  # installers: users install them from Settings › Plugins. Without the
+  # signing key (secret PLUGIN_SIGNING_KEY: the file `openidea-plugin keygen`
+  # writes) nothing is published and the release goes on.
+  plugins:
+    needs: create-release
+    name: Official plugins
+    runs-on: ubuntu-22.04
+    env:
+      SIGNING_KEY: ${{ secrets.PLUGIN_SIGNING_KEY }}
+    steps:
+      - id: key
+        run: |
+          if [ -z "$SIGNING_KEY" ]; then
+            echo "::warning::PLUGIN_SIGNING_KEY is not set: the official plugins are not published"
+            echo "skip=true" >> "$GITHUB_OUTPUT"
+          fi
+      - uses: actions/checkout@v4
+        if: steps.key.outputs.skip != 'true'
+        with: { ref: "${{ env.TAG }}" }
+      - uses: dtolnay/rust-toolchain@stable
+        if: steps.key.outputs.skip != 'true'
+        with: { targets: wasm32-wasip2 }
+      - uses: Swatinem/rust-cache@v2
+        if: steps.key.outputs.skip != 'true'
+        with: { key: release-plugins }
+      - uses: pnpm/action-setup@v4
+        if: steps.key.outputs.skip != 'true'
+        with: { version: 11 }
+      - uses: actions/setup-node@v4
+        if: steps.key.outputs.skip != 'true'
+        with: { node-version: 22 }
+      # Builds the web pages; fails when a checked-in component isn't built from these sources.
+      - name: Build
+        if: steps.key.outputs.skip != 'true'
+        run: |
+          plugins/build.sh --check
+          cargo build --release --locked -p ide-host --bin openidea-plugin
+      - name: Pack, index and upload
+        if: steps.key.outputs.skip != 'true'
+        shell: bash
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          set -euo pipefail
+          tool="$PWD/target/release/openidea-plugin"
+          key="$RUNNER_TEMP/openidea.key"
+          out="$RUNNER_TEMP/market"
+          (umask 077 && printf '%s' "$SIGNING_KEY" > "$key")
+          trap 'rm -f "$key"' EXIT
+          mkdir -p "$out"
+          for dir in plugins/official/*/; do
+            id="$(sed -n 's/^id *= *"\(.*\)".*/\1/p' "$dir/plugin.toml" | head -1)"
+            version="$(sed -n 's/^version *= *"\(.*\)".*/\1/p' "$dir/plugin.toml" | head -1)"
+            "$tool" pack "$dir" --key "$key" --publisher openidea --out "$out/$id-$version.oiplugin"
+          done
+          # The published index's revocations and earlier keys carry over.
+          curl -fsSL "https://github.com/$GITHUB_REPOSITORY/releases/latest/download/plugins-index.json" \
+            -o "$out/plugins-index.json" || rm -f "$out/plugins-index.json"
+          "$tool" index "$out" --publisher openidea --name OpenIDEA --key "$key" --out "$out/plugins-index.json"
+          gh release upload "$TAG" "$out"/*.oiplugin "$out/plugins-index.json" --clobber
+
   # The updater manifest (latest.json), built once from the signed bundles every build uploaded.
   # Fails when a platform is missing, so a release never ships a manifest without it.
   updater-manifest:
@@ -243,7 +306,7 @@ jobs:
             core.info(`latest.json: ${Object.keys(platforms).sort().join(", ")}`);
 
   publish:
-    needs: [create-release, build, server, updater-manifest]
+    needs: [create-release, build, server, plugins, updater-manifest]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/github-script@v7

.gitignore

@@ -10,6 +10,9 @@ lerna-debug.log*
 node_modules
 dist
 dist-ssr
+# Plugin components are checked in (plugins/build.sh --check keeps them current).
+!plugins/official/*/dist
+!crates/ide-plugin/tests/fixtures/*/dist
 *.local
 
 # Editor directories and files

.oxfmtrc.json

@@ -15,6 +15,8 @@
     "pnpm-lock.yaml",
     "**/*.toml",
     "fixtures",
+    "plugins/*/web",
+    "plugins/official/*/web",
     "crates/**/tests/fixtures"
   ],
   "overrides": [

AGENTS.md

@@ -39,6 +39,7 @@ Visual style: dark, low-contrast greys, one cool accent
   icons from `src/ui/icons.tsx`, never emoji. Real `<button>`/`<input>`; `aria-label` on icon buttons.
 - User-visible text goes through the text catalog: add every new string to both
   `src/platform/locales/text/en.json` and `zh.json` (`textCatalog.test.ts` enforces it).
+  Other locales may lack entries; their UI shows the English text until a translator adds it.
 - Keep comments sparse and purposeful; match surrounding style.
 - For GUI verification, prefer Tauri MCP; use Computer Use only when Tauri MCP is
   unavailable or cannot cover the required checks.

Cargo.lock

@@ -4181,6 +4181,26 @@ dependencies = [
  "which",
 ]
 
+[[package]]
+name = "ide-extension"
+version = "0.1.35"
+dependencies = [
+ "base64 0.22.1",
+ "blake3",
+ "ed25519-dalek",
+ "ide-core",
+ "parking_lot",
+ "semver",
+ "serde",
+ "serde_json",
+ "specta",
+ "specta-typescript",
+ "tempfile",
+ "toml 0.9.12+spec-1.1.0",
+ "tracing",
+ "zip",
+]
+
 [[package]]
 name = "ide-fonts"
 version = "0.1.35"
@@ -4210,9 +4230,13 @@ dependencies = [
 name = "ide-host"
 version = "0.1.35"
 dependencies = [
+ "base64 0.22.1",
+ "criterion",
  "dirs 6.0.0",
  "dunce",
  "encoding_rs",
+ "getrandom 0.3.4",
+ "globset",
  "ide-agent",
  "ide-analysis",
  "ide-build",
@@ -4220,12 +4244,15 @@ dependencies = [
  "ide-coverage",
  "ide-dap",
  "ide-db",
+ "ide-docker",
+ "ide-extension",
  "ide-http",
  "ide-index",
  "ide-jsonrpc",
  "ide-language",
  "ide-lsp",
  "ide-notebook",
+ "ide-plugin",
  "ide-remote",
  "ide-run",
  "ide-sdk",
@@ -4239,7 +4266,9 @@ dependencies = [
  "ide-vcs",
  "ide-vfs",
  "ide-workspace",
+ "ignore",
  "parking_lot",
+ "reqwest",
  "rustix",
  "serde",
  "serde_json",
@@ -4247,10 +4276,12 @@ dependencies = [
  "specta-typescript",
  "tempfile",
  "tokio",
+ "toml 0.9.12+spec-1.1.0",
  "tracing",
  "tracing-subscriber",
  "uuid",
  "windows-sys 0.61.2",
+ "zip",
 ]
 
 [[package]]
@@ -4316,6 +4347,7 @@ dependencies = [
  "blake3",
  "criterion",
  "ide-core",
+ "ide-extension",
  "ide-text",
  "parking_lot",
  "regex-lite",
@@ -4417,19 +4449,20 @@ dependencies = [
 name = "ide-plugin"
 version = "0.1.35"
 dependencies = [
+ "blake3",
  "ide-core",
- "ide-language",
+ "ide-extension",
  "parking_lot",
+ "semver",
  "serde",
  "serde_json",
  "specta",
  "tempfile",
  "thiserror 2.0.21",
- "toml 0.9.12+spec-1.1.0",
+ "tokio",
  "tracing",
  "wasmtime",
  "wasmtime-wasi",
- "zip",
 ]
 
 [[package]]
@@ -6150,6 +6183,7 @@ dependencies = [
 name = "openidea"
 version = "0.1.35"
 dependencies = [
+ "base64 0.22.1",
  "blake3",
  "block2 0.6.2",
  "dirs 6.0.0",
@@ -6164,6 +6198,7 @@ dependencies = [
  "ide-dap",
  "ide-db",
  "ide-docker",
+ "ide-extension",
  "ide-fonts",
  "ide-github",
  "ide-host",
@@ -6195,6 +6230,8 @@ dependencies = [
  "objc2-foundation 0.3.2",
  "objc2-web-kit 0.3.2",
  "parking_lot",
+ "percent-encoding",
+ "security-framework",
  "serde",
  "serde_json",
  "specta",

Cargo.toml

@@ -1,6 +1,8 @@
 [workspace]
 resolver = "3"
 members = ["crates/*", "src-tauri"]
+# Plugins and the guest SDK build for wasm32-wasip2 in their own workspaces.
+exclude = ["sdk", "plugins"]
 
 [workspace.package]
 version = "0.1.35"
@@ -41,6 +43,8 @@ ide-ssh = { path = "crates/ide-ssh" }
 ide-remote = { path = "crates/ide-remote" }
 ide-host = { path = "crates/ide-host" }
 ide-notebook = { path = "crates/ide-notebook" }
+ide-extension = { path = "crates/ide-extension" }
+ide-plugin = { path = "crates/ide-plugin" }
 
 # serialization & IPC typing
 serde = { version = "1", features = ["derive"] }
@@ -69,6 +73,7 @@ ropey = "1.6"
 encoding_rs = "0.8"
 chardetng = "0.1"
 ignore = "0.4"
+base64 = "0.22"
 globset = "0.4"
 notify = "8"
 notify-debouncer-full = "0.6"

crates/ide-agent/src/lib.rs

@@ -345,6 +345,14 @@ impl AgentManager {
         provider::set_builtin_command(&dir, id, command.as_deref())
     }
 
+    /// Sets the environment variables built-in `id` starts with; empty clears them.
+    pub fn set_builtin_env(&self, id: &str, env: std::collections::BTreeMap<String, String>) -> IdeResult<()> {
+        let Some(dir) = self.shared.paths.custom_agents_dir.clone() else {
+            return Err(IdeError::unavailable("there is no custom agents directory"));
+        };
+        provider::set_builtin_env(&dir, id, env)
+    }
+
     /// Re-reads configured/installed agents, drops cached probes, and notifies subscribers.
     pub fn reload_providers(&self) {
         let specs = provider::load(self.shared.paths.custom_agents_dir.as_deref());

crates/ide-agent/src/model.rs

@@ -3,6 +3,7 @@
 use ide_core::IpcPath;
 use serde::{Deserialize, Serialize};
 use specta::Type;
+use std::collections::BTreeMap;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
 #[serde(rename_all = "camelCase")]
@@ -357,6 +358,8 @@ pub struct AgentProvider {
     pub command_read_only_reason: Option<AgentCommandReadOnlyReason>,
     /// Whether the command was found (on `PATH`).
     pub installed: bool,
+    /// Environment variables it starts with (from its agent file).
+    pub env: BTreeMap<String, String>,
     /// Settings (models, modes…) the agent offered last time it ran; empty before its first session.
     pub config: Vec<AgentConfigOption>,
     /// Slash commands it offered last time.

crates/ide-agent/src/provider.rs

@@ -124,6 +124,7 @@ pub(crate) fn describe(spec: &ProviderSpec) -> AgentProvider {
         command_editable: reason.is_none(),
         command_read_only_reason: reason,
         installed: installed(&spec.command),
+        env: spec.env.iter().cloned().collect(),
         config: vec![],
         commands: vec![],
         source: spec.source.clone(),
@@ -133,6 +134,16 @@ pub(crate) fn describe(spec: &ProviderSpec) -> AgentProvider {
 /// Overrides built-in `id`'s command through its agent file, preserving other
 /// customizations. `None` restores the built-in command and removes a redundant file.
 pub(crate) fn set_builtin_command(custom_dir: &Path, id: &str, command: Option<&str>) -> IdeResult<()> {
+    update_builtin(custom_dir, id, |agent, builtin| agent.command = command.unwrap_or(&builtin.command).to_owned())
+}
+
+/// The environment built-in `id` starts with, through its agent file (empty clears it).
+pub(crate) fn set_builtin_env(custom_dir: &Path, id: &str, env: BTreeMap<String, String>) -> IdeResult<()> {
+    update_builtin(custom_dir, id, |agent, _| agent.env = env)
+}
+
+/// Changes built-in `id`'s agent file; a file left with only the built-in's values is removed.
+fn update_builtin(custom_dir: &Path, id: &str, change: impl FnOnce(&mut CustomAgent, &ProviderSpec)) -> IdeResult<()> {
     let Some(builtin) = builtin_spec(id) else {
         return Err(IdeError::invalid(format!("{id} is not a built-in agent")));
     };
@@ -152,7 +163,8 @@ pub(crate) fn set_builtin_command(custom_dir: &Path, id: &str, command: Option<&
     if agent.registry.is_some() {
         return Err(IdeError::invalid(format!("{id} is installed from the ACP Registry")));
     }
-    if command.is_none()
+    change(&mut agent, &builtin);
+    if agent.command == builtin.command
         && agent.name.as_deref() == Some(builtin.name.as_str())
         && agent.driver == builtin.driver
         && agent.args == builtin.args
@@ -164,7 +176,6 @@ pub(crate) fn set_builtin_command(custom_dir: &Path, id: &str, command: Option<&
         }
         return Ok(());
     }
-    agent.command = command.unwrap_or(&builtin.command).to_owned();
     agent.write(&file)?;
     Ok(())
 }
@@ -368,6 +379,23 @@ mod tests {
         assert!(installed("sh"));
     }
 
+    #[test]
+    fn set_builtin_env_writes_and_clears_the_environment() {
+        let dir = tempfile::tempdir().unwrap();
+        let env = BTreeMap::from([("CLAUDE_CODE_ENTRYPOINT".to_owned(), "openidea".to_owned())]);
+        set_builtin_env(dir.path(), "claude", env.clone()).unwrap();
+        let claude = load(Some(dir.path())).into_iter().find(|s| s.id == "claude").unwrap();
+        assert_eq!(claude.env, vec![("CLAUDE_CODE_ENTRYPOINT".to_owned(), "openidea".to_owned())]);
+        assert_eq!(describe(&claude).env, env);
+        // The command override and the environment are kept independently.
+        set_builtin_command(dir.path(), "claude", Some("/opt/claude")).unwrap();
+        set_builtin_command(dir.path(), "claude", None).unwrap();
+        assert!(dir.path().join("claude.toml").is_file());
+        set_builtin_env(dir.path(), "claude", BTreeMap::new()).unwrap();
+        assert!(!dir.path().join("claude.toml").exists());
+        set_builtin_env(dir.path(), "not-a-builtin", env).unwrap_err();
+    }
+
     #[test]
     fn set_builtin_command_overrides_and_clears_a_builtin() {
         let dir = tempfile::tempdir().unwrap();

crates/ide-build/src/compile/mod.rs

@@ -10,6 +10,7 @@ pub use fingerprint::{LaunchFingerprint, launch_fingerprint};
 
 use crate::process::{self, Stream};
 use crate::{BuildModel, maven};
+use ide_core::settings::CMakeProfile;
 use ide_core::{CancellationToken, Diagnostic, IdeError, IdeResult, Pos, Range, Severity};
 use parse::{ColUnit, Format, OutputParser, RawMessage};
 use serde::{Deserialize, Serialize};
@@ -41,6 +42,8 @@ pub enum BuildSystem {
     Go,
     #[serde(rename = "typescript")]
     TypeScript,
+    #[serde(rename = "cmake")]
+    CMake,
 }
 
 /// One command of a build.
@@ -152,6 +155,8 @@ fn detect_dir(dir: &Path, model: &BuildModel, root: &Path) -> Option<BuildSystem
         Some(BuildSystem::Go)
     } else if has(dir, &["tsconfig.json", "package.json"]) {
         Some(BuildSystem::TypeScript)
+    } else if has(dir, &["CMakeLists.txt"]) {
+        Some(BuildSystem::CMake)
     } else {
         None
     }
@@ -176,7 +181,14 @@ fn ancestors_within<'a>(root: &'a Path, file: &'a Path) -> impl Iterator<Item =
 }
 
 /// The build of `root`, or of the module containing `file` (Build Module / Recompile).
-pub fn plan(root: &Path, model: &BuildModel, kind: BuildKind, file: Option<&Path>) -> IdeResult<BuildPlan> {
+/// `cmake`: the CMake profiles of the settings (the first one is built), if any.
+pub fn plan(
+    root: &Path,
+    model: &BuildModel,
+    kind: BuildKind,
+    file: Option<&Path>,
+    cmake: Option<&[CMakeProfile]>,
+) -> IdeResult<BuildPlan> {
     let project_name = root.file_name().map_or_else(|| "project".to_owned(), |n| n.to_string_lossy().into_owned());
     let module_dir = match file {
         Some(f) => {
@@ -192,7 +204,9 @@ pub fn plan(root: &Path, model: &BuildModel, kind: BuildKind, file: Option<&Path
     let system = detect_dir(&dir, model, root)
         .or_else(|| if model.gradle.is_some() { Some(BuildSystem::Gradle) } else { None })
         .or_else(|| model.maven.as_ref().filter(|m| !m.projects.is_empty()).map(|_| BuildSystem::Maven))
-        .ok_or_else(|| IdeError::not_found("no supported build system (Maven, Gradle, Cargo, Go, TypeScript) found"))?;
+        .ok_or_else(|| {
+            IdeError::not_found("no supported build system (Maven, Gradle, Cargo, Go, TypeScript, CMake) found")
+        })?;
     let module = module_dir.as_deref().filter(|d| *d != root);
     let title = match module {
         Some(d) => format!(
@@ -209,6 +223,7 @@ pub fn plan(root: &Path, model: &BuildModel, kind: BuildKind, file: Option<&Path
         // Go builds the file's package (a module holds many).
         BuildSystem::Go => go_steps(file.and_then(Path::parent).unwrap_or(&dir), kind),
         BuildSystem::TypeScript => ts_steps(&dir, kind),
+        BuildSystem::CMake => cmake_steps(&dir, kind, cmake.and_then(<[_]>::first)),
     };
     Ok(BuildPlan { system, title, steps })
 }
@@ -302,6 +317,50 @@ fn cargo_steps(dir: &Path, kind: BuildKind) -> Vec<BuildStep> {
     }
 }
 
+/// CLion's Build Project for a CMake project: configures the build directory when it has no
+/// `CMakeCache.txt` yet, then `cmake --build` (`--clean-first` to rebuild). The directory and
+/// options come from the CMake profile; without one, a configured directory of the project
+/// (the first by name), else `build`, as the generated run configurations use.
+fn cmake_steps(dir: &Path, kind: BuildKind, profile: Option<&CMakeProfile>) -> Vec<BuildStep> {
+    let build_dir = match profile {
+        Some(p) if !p.build_dir.trim().is_empty() => p.build_dir.trim().to_owned(),
+        Some(p) => format!("cmake-build-{}", p.build_type.to_lowercase()),
+        None => {
+            let mut configured: Vec<String> = std::fs::read_dir(dir)
+                .into_iter()
+                .flatten()
+                .flatten()
+                .filter(|e| e.path().join("CMakeCache.txt").is_file())
+                .map(|e| e.file_name().to_string_lossy().into_owned())
+                .collect();
+            configured.sort();
+            configured.into_iter().next().unwrap_or_else(|| "build".into())
+        }
+    };
+    let build_type = profile.map_or("Debug", |p| p.build_type.as_str());
+    let env = profile.map(|p| p.env.clone()).unwrap_or_default();
+    let mut steps = Vec::new();
+    if !dir.join(&build_dir).join("CMakeCache.txt").is_file() {
+        let mut configure = BuildStep::new("cmake", &["-S", ".", "-B", &build_dir], dir, Format::Gcc);
+        if let Some(p) = profile.filter(|p| !p.generator.trim().is_empty()) {
+            configure.args.extend(["-G".into(), p.generator.clone()]);
+        }
+        configure.args.push(format!("-DCMAKE_BUILD_TYPE={build_type}"));
+        configure.args.push("-DCMAKE_EXPORT_COMPILE_COMMANDS=ON".into());
+        configure.args.extend(profile.map(|p| p.cmake_args.clone()).unwrap_or_default());
+        configure.env = env.clone();
+        steps.push(configure);
+    }
+    let mut build = BuildStep::new("cmake", &["--build", &build_dir, "--config", build_type], dir, Format::Gcc);
+    if kind == BuildKind::Rebuild {
+        build.args.push("--clean-first".into());
+    }
+    build.args.extend(profile.map(|p| p.build_args.clone()).unwrap_or_default());
+    build.env = env;
+    steps.push(build);
+    steps
+}
+
 fn go_steps(dir: &Path, kind: BuildKind) -> Vec<BuildStep> {
     let module_root = dir.ancestors().find(|d| d.join("go.mod").is_file()).unwrap_or(dir);
     let target = if module_root == dir { "./...".to_owned() } else { format!("./{}/...", rel_str(module_root, dir)) };
@@ -687,7 +746,7 @@ fn launch_plan(root: &Path, model: &BuildModel, module: &Path, test: bool) -> Id
     } else {
         BuildKind::Build
     };
-    let mut plan = plan(root, model, kind, Some(module))?;
+    let mut plan = plan(root, model, kind, Some(module), None)?;
     if plan.system == BuildSystem::Maven && !test {
         for step in &mut plan.steps {
             if let Some(goal) = step.args.last_mut() {
@@ -796,12 +855,12 @@ mod tests {
         write(&root, "core/pom.xml", "<project><artifactId>core</artifactId></project>");
         write(&root, "core/src/main/java/A.java", "class A {}");
         let model = crate::load(&root, &tmp.path().join("cache"), None);
-        let p = plan(&root, &model, BuildKind::Build, None).unwrap();
+        let p = plan(&root, &model, BuildKind::Build, None, None).unwrap();
         assert_eq!(p.system, BuildSystem::Maven);
         assert_eq!(p.title, "demo");
         assert_eq!(p.steps.len(), 1);
         assert_eq!(p.steps[0].args, ["-B", "-Dstyle.color=never", "test-compile"]);
-        let p = plan(&root, &model, BuildKind::Rebuild, Some(&root.join("core/src/main/java/A.java"))).unwrap();
+        let p = plan(&root, &model, BuildKind::Rebuild, Some(&root.join("core/src/main/java/A.java")), None).unwrap();
         assert_eq!(p.steps[0].args, ["-B", "-Dstyle.color=never", "-pl", "core", "-am", "clean", "test-compile"]);
         assert_eq!(p.steps[0].cwd, root);
         assert_eq!(p.title, "demo: build module 'core'");
@@ -810,24 +869,24 @@ mod tests {
         write(&g, "settings.gradle", "include 'app'");
         write(&g, "app/build.gradle", "apply plugin: 'java'");
         let model = crate::load(&g, &tmp.path().join("cache2"), None);
-        let p = plan(&g, &model, BuildKind::Build, Some(&g.join("app/src/A.java"))).unwrap();
+        let p = plan(&g, &model, BuildKind::Build, Some(&g.join("app/src/A.java")), None).unwrap();
         assert_eq!(p.system, BuildSystem::Gradle);
         assert_eq!(p.steps[0].args, ["--console=plain", ":app:classes", ":app:testClasses"]);
         assert_eq!(
-            plan(&g, &model, BuildKind::Artifacts, None).unwrap().steps[0].args,
+            plan(&g, &model, BuildKind::Artifacts, None, None).unwrap().steps[0].args,
             ["--console=plain", "assemble"]
         );
 
         let c = tmp.path().join("c");
         write(&c, "Cargo.toml", "[package]\nname='c'");
-        let p = plan(&c, &BuildModel::default(), BuildKind::Rebuild, None).unwrap();
+        let p = plan(&c, &BuildModel::default(), BuildKind::Rebuild, None, None).unwrap();
         assert_eq!(p.system, BuildSystem::Cargo);
         assert_eq!(p.steps.len(), 2);
         assert_eq!(p.steps[0].args[0], "clean");
 
         let go = tmp.path().join("go");
         write(&go, "go.mod", "module x");
-        let p = plan(&go, &BuildModel::default(), BuildKind::Build, Some(&go.join("pkg/a/a.go"))).unwrap();
+        let p = plan(&go, &BuildModel::default(), BuildKind::Build, Some(&go.join("pkg/a/a.go")), None).unwrap();
         assert_eq!(p.steps[0].args, ["build", "./pkg/a/..."]);
         assert_eq!(p.steps[0].cwd, go);
 
@@ -835,19 +894,51 @@ mod tests {
         write(&ts, "package.json", r#"{"scripts":{"build":"vite build"}}"#);
         write(&ts, "tsconfig.json", "{}");
         write(&ts, "pnpm-lock.yaml", "");
-        let p = plan(&ts, &BuildModel::default(), BuildKind::Build, None).unwrap();
+        let p = plan(&ts, &BuildModel::default(), BuildKind::Build, None, None).unwrap();
         assert_eq!(p.steps[0].args, ["--noEmit", "--pretty", "false", "-p", "."]);
-        let p = plan(&ts, &BuildModel::default(), BuildKind::Artifacts, None).unwrap();
+        let p = plan(&ts, &BuildModel::default(), BuildKind::Artifacts, None, None).unwrap();
         assert_eq!(
             (p.steps[0].program.as_str(), p.steps[0].args.as_slice()),
             ("pnpm", &["run".to_owned(), "build".to_owned()][..])
         );
 
+        let cm = tmp.path().join("cm");
+        write(&cm, "CMakeLists.txt", "project(app)");
+        let args = |p: &BuildPlan| p.steps.iter().map(|s| s.args.join(" ")).collect::<Vec<_>>();
+        let p = plan(&cm, &BuildModel::default(), BuildKind::Build, None, None).unwrap();
+        assert_eq!(p.system, BuildSystem::CMake);
+        assert_eq!(
+            args(&p),
+            [
+                "-S . -B build -DCMAKE_BUILD_TYPE=Debug -DCMAKE_EXPORT_COMPILE_COMMANDS=ON",
+                "--build build --config Debug"
+            ],
+            "an unconfigured project is configured first"
+        );
+        write(&cm, "cmake-build-release/CMakeCache.txt", "");
+        let p = plan(&cm, &BuildModel::default(), BuildKind::Rebuild, None, None).unwrap();
+        assert_eq!(
+            args(&p),
+            ["--build cmake-build-release --config Debug --clean-first"],
+            "a configured directory is reused"
+        );
+        let profile = CMakeProfile {
+            build_type: "Release".into(),
+            generator: "Ninja".into(),
+            build_args: vec!["-j".into(), "8".into()],
+            ..CMakeProfile::default()
+        };
+        let p =
+            plan(&cm, &BuildModel::default(), BuildKind::Build, None, Some(std::slice::from_ref(&profile))).unwrap();
+        assert_eq!(args(&p), ["--build cmake-build-release --config Release -j 8"]);
+        let p = plan(&cm, &BuildModel::default(), BuildKind::Build, None, Some(&[CMakeProfile::default()])).unwrap();
+        assert_eq!(p.steps[0].args[..4], ["-S", ".", "-B", "cmake-build-debug"]);
+
         let siblings = tmp.path().join("siblings");
         write(&siblings, "core/pom.xml", "<project><artifactId>core</artifactId></project>");
         write(&siblings, "system/pom.xml", "<project><artifactId>system</artifactId></project>");
         let model = crate::load(&siblings, &tmp.path().join("cache3"), None);
-        let p = plan(&siblings, &model, BuildKind::Build, None).unwrap();
+        let p = plan(&siblings, &model, BuildKind::Build, None, None).unwrap();
         assert_eq!(p.system, BuildSystem::Maven);
         assert_eq!(
             p.steps.iter().map(|s| s.cwd.clone()).collect::<Vec<_>>(),
@@ -856,7 +947,7 @@ mod tests {
 
         let none = tmp.path().join("none");
         std::fs::create_dir_all(&none).unwrap();
-        assert!(plan(&none, &BuildModel::default(), BuildKind::Build, None).is_err());
+        assert!(plan(&none, &BuildModel::default(), BuildKind::Build, None, None).is_err());
     }
 
     #[test]

crates/ide-build/src/compile/parse.rs

@@ -22,6 +22,8 @@ pub(crate) enum Format {
     Tsc,
     /// `go build`: `./a.go:12:5: msg`.
     Go,
+    /// GCC / Clang (through `cmake --build`): `src/a.cpp:12:5: error: msg`.
+    Gcc,
 }
 
 /// What a printed column counts.
@@ -296,6 +298,17 @@ fn go_line(line: &str) -> Option<RawMessage> {
     (!msg.is_empty()).then(|| RawMessage::new(Severity::Error, msg, ColUnit::Byte).at(path, ln, col))
 }
 
+/// A GCC / Clang diagnostic line; notes and the context lines after it are left as output.
+fn gcc_line(line: &str) -> Option<RawMessage> {
+    let (path, ln, col, rest) = path_line_col(line)?;
+    let rest = rest.strip_prefix(':')?.trim_start();
+    let (severity, msg) =
+        [("fatal error:", Severity::Error), ("error:", Severity::Error), ("warning:", Severity::Warning)]
+            .into_iter()
+            .find_map(|(prefix, severity)| rest.strip_prefix(prefix).map(|m| (severity, m.trim())))?;
+    (!msg.is_empty()).then(|| RawMessage::new(severity, msg, ColUnit::Byte).at(path, ln, col))
+}
+
 /// rustc's JSON diagnostic (`reason: compiler-message`) → message and its rendered text.
 fn cargo_json(v: &Value) -> Option<(Option<RawMessage>, String)> {
     if v.get("reason")?.as_str()? != "compiler-message" {
@@ -410,6 +423,7 @@ impl OutputParser {
             Format::Gradle => javac_header(&line).or_else(|| kotlin_line(&line)),
             Format::Tsc => tsc_line(&line),
             Format::Go => go_line(&line),
+            Format::Gcc => gcc_line(&line),
             Format::Cargo => None,
         };
         if let Some(msg) = parsed {
@@ -563,6 +577,24 @@ mod tests {
         assert_eq!(out[2].text, "Cannot find name 'foo'.");
     }
 
+    #[test]
+    fn gcc_errors_and_warnings() {
+        let out = parse(
+            Format::Gcc,
+            "[1/2] Building CXX object CMakeFiles/app.dir/main.cpp.o\n\
+             /p/src/main.cpp:12:5: error: use of undeclared identifier 'foo'\n\
+             \x20  12 |     foo();\n\
+             /p/src/util.h:3:10: warning: unused variable 'x' [-Wunused-variable]\n\
+             /p/src/main.cpp:4:10: fatal error: 'missing.h' file not found\n\
+             /p/src/main.cpp:2:1: note: in file included from here\n",
+        );
+        assert_eq!(out.len(), 3, "{out:?}");
+        assert_eq!(out[0].severity, Severity::Error);
+        assert_eq!(out[0].text, "use of undeclared identifier 'foo'");
+        assert_eq!(out[1].severity, Severity::Warning);
+        assert_eq!(out[2].text, "'missing.h' file not found");
+    }
+
     #[test]
     fn go_errors() {
         let out = parse(

crates/ide-build/src/kotlin_bridge.rs

@@ -81,7 +81,7 @@ pub fn build(
     cancel: &CancellationToken,
 ) -> IdeResult<Outcome> {
     std::fs::create_dir_all(generation)?;
-    let mut plan = compile::plan(root, model, BuildKind::Build, None)?;
+    let mut plan = compile::plan(root, model, BuildKind::Build, None, None)?;
     if plan.system != compile::BuildSystem::Maven {
         return Err(IdeError::invalid("Kotlin bridge requires a Maven build root"));
     }

crates/ide-build/src/lib.rs

@@ -53,7 +53,8 @@ pub fn load_linked(
     settings: &ide_core::settings::MavenSettings,
 ) -> BuildModel {
     let maven = maven::is_maven_project(root).then(|| {
-        let mut m = maven::load_with_repo(root, maven_repo.or_else(maven::default_local_repo));
+        let profiles = sync::maven_profiles(cache_dir);
+        let mut m = maven::load_with(root, maven_repo.or_else(maven::default_local_repo), &profiles);
         maven::UnlinkedProjects::from_model(&m, settings).filter(&mut m);
         sync::apply_maven_cache(root, cache_dir, &mut m);
         m

crates/ide-build/src/maven.rs

@@ -460,6 +460,8 @@ const MAX_PARENT_DEPTH: usize = 10;
 
 struct Resolver {
     local_repo: Option<PathBuf>,
+    /// The chosen profiles (`-P` entries; `!id` / `-id` deactivates).
+    profiles: Vec<String>,
     poms: HashMap<PathBuf, Option<RawPom>>,
     contexts: HashMap<PathBuf, Inherited>,
 }
@@ -484,8 +486,16 @@ pub fn local_repository_of(settings: &Path) -> Option<PathBuf> {
 }
 
 impl Resolver {
-    fn new(local_repo: Option<PathBuf>) -> Self {
-        Self { local_repo, poms: HashMap::new(), contexts: HashMap::new() }
+    fn new(local_repo: Option<PathBuf>, profiles: &[String]) -> Self {
+        Self { local_repo, profiles: profiles.to_vec(), poms: HashMap::new(), contexts: HashMap::new() }
+    }
+
+    /// The active profiles of a POM: the chosen ones, and the `activeByDefault` ones not turned
+    /// off while none of the POM's other profiles is chosen (Maven's rule).
+    fn active<'a>(&self, profiles: &'a [RawProfile]) -> impl Iterator<Item = &'a RawProfile> {
+        let chosen = |id: &str| profile_choice(&self.profiles, id);
+        let any_chosen = profiles.iter().any(|p| chosen(&p.id) == Some(true));
+        profiles.iter().filter(move |p| chosen(&p.id).unwrap_or(p.active_by_default && !any_chosen))
     }
 
     fn pom(&mut self, path: &Path) -> Option<RawPom> {
@@ -550,7 +560,7 @@ impl Resolver {
         if pom.compiler_release.is_some() {
             ctx.compiler_release = pom.compiler_release.clone();
         }
-        for p in pom.profiles.iter().filter(|p| p.active_by_default) {
+        for p in self.active(&pom.profiles) {
             merge_by(&mut ctx.properties, &p.properties, |(k, _)| k.clone());
             merge_by(&mut ctx.deps, &p.deps, RawDep::key);
             merge_plugins(&mut ctx.plugins, &p.plugins);
@@ -666,7 +676,7 @@ pub(crate) fn launch_inputs(
         }
         Some(())
     }
-    let mut resolver = Resolver::new(local_repo.or_else(default_local_repo));
+    let mut resolver = Resolver::new(local_repo.or_else(default_local_repo), &[]);
     let mut out = Vec::new();
     for project in projects {
         let dir = root.join(&project.dir);
@@ -1055,8 +1065,32 @@ pub fn load(root: &Path) -> MavenModel {
     load_with_repo(root, default_local_repo())
 }
 
+/// [`load`] with the chosen `profiles` (`-P` entries; `!id` deactivates): their modules,
+/// dependencies and properties are part of the model, those turned off are not.
+pub fn load_with_profiles(root: &Path, profiles: &[String]) -> MavenModel {
+    load_with(root, default_local_repo(), profiles)
+}
+
 pub(crate) fn load_with_repo(root: &Path, local_repo: Option<PathBuf>) -> MavenModel {
-    let mut resolver = Resolver::new(local_repo);
+    load_with(root, local_repo, &[])
+}
+
+/// The `-P` entries' choice for profile `id`: on, off (`!id` / `-id`), or none (the last wins).
+fn profile_choice(chosen: &[String], id: &str) -> Option<bool> {
+    chosen.iter().rev().find_map(|c| {
+        let c = c.trim();
+        if c == id {
+            Some(true)
+        } else if c.strip_prefix('!').or_else(|| c.strip_prefix('-')) == Some(id) {
+            Some(false)
+        } else {
+            None
+        }
+    })
+}
+
+pub(crate) fn load_with(root: &Path, local_repo: Option<PathBuf>, profiles: &[String]) -> MavenModel {
+    let mut resolver = Resolver::new(local_repo, profiles);
     let mut model = MavenModel::default();
     let mut seen: HashSet<PathBuf> = HashSet::new();
     // (pom, aggregated)
@@ -1076,7 +1110,7 @@ pub(crate) fn load_with_repo(root: &Path, local_repo: Option<PathBuf>) -> MavenM
         let i = |s: &str| interpolate(s, &props);
 
         let mut module_names: Vec<String> = pom.modules.clone();
-        for p in pom.profiles.iter().filter(|p| p.active_by_default) {
+        for p in resolver.active(&pom.profiles) {
             module_names.extend(p.modules.iter().cloned());
         }
         let mut modules: Vec<PathBuf> = Vec::new();
@@ -1699,6 +1733,52 @@ mod tests {
         assert!(model.projects.iter().all(|p| p.command == if cfg!(windows) { "mvn.cmd" } else { "mvn" }));
     }
 
+    #[test]
+    fn chosen_profiles_bring_their_modules_and_dependencies() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        write(
+            root,
+            "pom.xml",
+            r#"<project><groupId>demo</groupId><artifactId>parent</artifactId><version>1.0</version><packaging>pom</packaging>
+              <modules><module>core</module></modules>
+              <profiles>
+                <profile><id>flink-1.17</id><activation><activeByDefault>true</activeByDefault></activation>
+                  <modules><module>flink-1.17</module></modules></profile>
+                <profile><id>flink-1.20</id><modules><module>flink-1.20</module></modules>
+                  <dependencies><dependency><groupId>org.apache.flink</groupId><artifactId>flink-core</artifactId><version>1.20.0</version></dependency></dependencies>
+                </profile>
+              </profiles>
+            </project>"#,
+        );
+        for m in ["core", "flink-1.17", "flink-1.20"] {
+            write(
+                root,
+                &format!("{m}/pom.xml"),
+                &format!(
+                    "<project><parent><groupId>demo</groupId><artifactId>parent</artifactId><version>1.0</version></parent><artifactId>{m}</artifactId></project>"
+                ),
+            );
+        }
+        let dirs = |m: &MavenModel| m.projects.iter().map(|p| p.dir.clone()).collect::<Vec<_>>();
+        let flink = |m: &MavenModel, dir: &str| {
+            m.projects.iter().find(|p| p.dir == dir).unwrap().dependencies.iter().any(|d| d.artifact_id == "flink-core")
+        };
+
+        let default = load_with(root, None, &[]);
+        assert_eq!(dirs(&default), ["", "core", "flink-1.17"]);
+        assert!(!flink(&default, "core"));
+
+        // Choosing another profile of the POM turns its activeByDefault one off (as `-P` does).
+        let chosen = load_with(root, None, &["flink-1.20".into()]);
+        assert_eq!(dirs(&chosen), ["", "core", "flink-1.20"]);
+        assert!(flink(&chosen, "core"), "a module inherits the chosen profile's dependencies");
+
+        let both = load_with(root, None, &["flink-1.20".into(), "flink-1.17".into()]);
+        assert_eq!(dirs(&both), ["", "core", "flink-1.17", "flink-1.20"]);
+        assert_eq!(dirs(&load_with(root, None, &["!flink-1.17".into()])), ["", "core"]);
+    }
+
     #[test]
     fn profiles_of_a_parent_pom_are_inherited() {
         let tmp = tempfile::tempdir().unwrap();

crates/ide-build/src/sync.rs

@@ -283,7 +283,7 @@ pub fn sync_maven(
     cancel: &CancellationToken,
     progress: &dyn Fn(SyncProgress),
 ) -> IdeResult<()> {
-    let mut model = maven::load(root);
+    let mut model = maven::load_with_profiles(root, &options.profiles);
     maven::UnlinkedProjects::from_model(&model, &options.maven_settings).filter(&mut model);
     std::fs::create_dir_all(cache_dir)?;
     let mut cache = MavenCache {

crates/ide-core/src/settings.rs

@@ -61,6 +61,9 @@ pub struct Settings {
     pub cmake: CMakeSettings,
     /// Tools › Agents › Chat.
     pub agents: AgentSettings,
+    /// 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>>,
 }
 
 /// What the meters in an agent task's header show.
@@ -154,6 +157,16 @@ pub struct LanguageServerSettings {
     pub languages: Vec<String>,
     /// Files marking a workspace root for a server defined here (`pyproject.toml`).
     pub root_markers: Vec<String>,
+    /// Replaces the definition's `features`: what the server is used for
+    /// (`code-action`, `hover`, …); an empty list means everything.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[specta(optional)]
+    pub features: Option<Vec<String>>,
+    /// Replaces the definition's `code-action-kinds` (`refactor`); an empty
+    /// list keeps every kind.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[specta(optional)]
+    pub code_action_kinds: Option<Vec<String>>,
 }
 
 impl Default for LanguageServerSettings {
@@ -167,6 +180,8 @@ impl Default for LanguageServerSettings {
             settings: None,
             languages: Vec::new(),
             root_markers: Vec::new(),
+            features: None,
+            code_action_kinds: None,
         }
     }
 }
@@ -215,6 +230,7 @@ impl Default for Settings {
             run_targets: Vec::new(),
             cmake: CMakeSettings::default(),
             agents: AgentSettings::default(),
+            plugins: BTreeMap::new(),
         }
     }
 }
@@ -323,7 +339,8 @@ impl Default for NotificationGroupSettings {
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
 #[serde(default, rename_all = "camelCase")]
 pub struct AppearanceSettings {
-    /// `dark` | `light` | `system` | `dark-hc` (high-contrast dark)
+    /// A built-in theme id (`light`, `dark`, `dark-hc`, …), `system` (legacy
+    /// "Sync with OS"), or a plugin's theme: `plugin:<plugin-id>/<theme-id>`.
     pub theme: String,
     pub accent: String,
     pub ui_font_size: f32,
@@ -332,6 +349,8 @@ pub struct AppearanceSettings {
     pub sync_with_os: bool,
     pub preferred_light_theme: String,
     pub preferred_dark_theme: String,
+    /// A plugin's file icon theme (`<plugin-id>/<theme-id>`); empty = the built-in icons.
+    pub file_icon_theme: String,
     /// IDE zoom in percent (50–300).
     pub zoom: u32,
     /// Apply `ui_font_family` / `ui_font_size` (otherwise the theme's).
@@ -386,6 +405,7 @@ impl Default for AppearanceSettings {
             sync_with_os: false,
             preferred_light_theme: "light".into(),
             preferred_dark_theme: "dark".into(),
+            file_icon_theme: String::new(),
             zoom: 100,
             use_custom_font: false,
             ui_font_family: "Inter".into(),

crates/ide-dap/src/adapter.rs

@@ -8,7 +8,7 @@
 
 use ide_core::process::executable_names;
 use ide_core::{IdeError, IdeResult};
-use ide_language::{DebuggerConfig, LanguageRegistry};
+use ide_language::{DebuggerConfig, LanguageRegistry, ProgramPin};
 use std::future::Future;
 use std::path::{Path, PathBuf};
 use std::pin::Pin;
@@ -44,6 +44,8 @@ pub struct AdapterSpec {
     /// `host:port` of an adapter inside another program (the Godot editor): connected to
     /// when it accepts, else `command` is started.
     pub connect: Option<String>,
+    /// A plugin language's adapter: start exactly this approved program.
+    pub pinned: Option<ProgramPin>,
 }
 
 /// Built-in adapters used when no language definition names `adapter`.
@@ -55,6 +57,7 @@ fn builtin(adapter: &str) -> Option<DebuggerConfig> {
         transport: transport.to_owned(),
         connect: None,
         install_hint: Some(hint.to_owned()),
+        pinned: None,
     };
     Some(match adapter {
         "codelldb" => cfg(
@@ -133,6 +136,7 @@ pub fn resolve(config: &DebuggerConfig, cwd: PathBuf) -> AdapterSpec {
         env: Vec::new(),
         server_host: None,
         connect: config.connect.clone(),
+        pinned: config.pinned.clone(),
     }
 }
 
@@ -426,12 +430,20 @@ impl AdapterLauncher for ProcessLauncher {
             if is_plugin_bundle(&spec.command) {
                 return Err(not_standalone(&spec));
             }
-            let (command, cwd) = (spec.command.clone(), spec.cwd.clone());
-            let binary = tokio::task::spawn_blocking(move || resolve_binary(&command, &cwd))
-                .await
-                .ok()
-                .flatten()
-                .ok_or_else(|| missing(&spec))?;
+            let binary = match spec.pinned.clone() {
+                Some(pin) => tokio::task::spawn_blocking(move || pin.verify().map(Path::to_path_buf))
+                    .await
+                    .map_err(|e| IdeError::internal(e.to_string()))?
+                    .map_err(|e| IdeError::new(ide_core::error::ErrorKind::PermissionDenied, e))?,
+                None => {
+                    let (command, cwd) = (spec.command.clone(), spec.cwd.clone());
+                    tokio::task::spawn_blocking(move || resolve_binary(&command, &cwd))
+                        .await
+                        .ok()
+                        .flatten()
+                        .ok_or_else(|| missing(&spec))?
+                }
+            };
             let port = match spec.transport {
                 // An embedded adapter started without `${port}` listens on its usual address.
                 Transport::Tcp => match &embedded {

crates/ide-dap/src/lib.rs

@@ -212,6 +212,19 @@ pub struct Variable {
     pub evaluate_name: Option<String>,
 }
 
+/// A completion the adapter offers for an expression (DAP `completions`).
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct DebugCompletion {
+    pub label: String,
+    /// What to insert, when it differs from `label`.
+    pub text: Option<String>,
+    /// DAP item type: `method`, `field`, `variable`, `class`, `keyword`, …
+    pub kind: Option<String>,
+    pub detail: Option<String>,
+    pub sort_text: Option<String>,
+}
+
 #[derive(Clone, Copy, Debug, Serialize, Deserialize, Type)]
 #[serde(rename_all = "camelCase")]
 pub enum StepKind {
@@ -1157,6 +1170,47 @@ impl DebugManager {
         })
     }
 
+    /// Completions for `text` at `line` / `column` (0-based, UTF-16) in the frame's scope; none
+    /// when the adapter doesn't offer them.
+    pub async fn completions(
+        &self,
+        s: DebugSessionId,
+        frame_id: Option<i64>,
+        text: String,
+        line: u32,
+        column: u32,
+    ) -> IdeResult<Vec<DebugCompletion>> {
+        let session = self.session(s)?;
+        if !session.supports("supportsCompletionsRequest") {
+            return Ok(Vec::new());
+        }
+        let mut args = json!({ "text": text, "line": line + 1, "column": column + 1 });
+        if let Some(f) = frame_id {
+            args["frameId"] = f.into();
+        }
+        let body = session.conn.request_timeout("completions", args, REQUEST_TIMEOUT).await?;
+        let text =
+            |v: &Value, key: &str| v.get(key).and_then(Value::as_str).filter(|t| !t.is_empty()).map(str::to_owned);
+        Ok(body
+            .get("targets")
+            .and_then(Value::as_array)
+            .map(|targets| {
+                targets
+                    .iter()
+                    .filter_map(|t| {
+                        Some(DebugCompletion {
+                            label: text(t, "label")?,
+                            text: text(t, "text"),
+                            kind: text(t, "type"),
+                            detail: text(t, "detail"),
+                            sort_text: text(t, "sortText"),
+                        })
+                    })
+                    .collect()
+            })
+            .unwrap_or_default())
+    }
+
     pub async fn resume(&self, s: DebugSessionId, thread_id: i64) -> IdeResult<()> {
         let session = self.session(s)?;
         let body = session.conn.request_timeout("continue", json!({ "threadId": thread_id }), REQUEST_TIMEOUT).await?;

crates/ide-dap/src/tests.rs

@@ -73,6 +73,7 @@ async fn fake_adapter<S: AsyncRead + AsyncWrite + Unpin + Send + 'static>(stream
                 msg,
                 json!({
                     "supportsConfigurationDoneRequest": true,
+                    "supportsCompletionsRequest": true,
                     "supportsTerminateRequest": true,
                     "supportsSetVariable": true,
                     "supportsFunctionBreakpoints": true,
@@ -172,6 +173,14 @@ async fn fake_adapter<S: AsyncRead + AsyncWrite + Unpin + Send + 'static>(stream
                 ]})
             ),
             "evaluate" => ok!(msg, json!({"result": "42", "type": "int", "variablesReference": 0})),
+            "completions" => ok!(
+                msg,
+                json!({"targets": [
+                    {"label": "getName()", "text": "getName", "type": "method", "detail": "String"},
+                    {"label": "name", "type": "field"},
+                    {"label": ""},
+                ]})
+            ),
             "continue" => {
                 ok!(msg, json!({"allThreadsContinued": true}));
                 send!(json!({"type": "event", "event": "exited", "body": {"exitCode": 3}}));
@@ -368,6 +377,14 @@ async fn full_protocol_flow() {
     let eval = h.request("evaluate");
     assert_eq!(eval["arguments"]["context"], "watch");
     assert_eq!(eval["arguments"]["frameId"], 10);
+    let items = h.manager.completions(id, Some(10), "req.na".into(), 0, 6).await.unwrap();
+    assert_eq!(
+        items.iter().map(|c| (c.label.as_str(), c.text.as_deref(), c.kind.as_deref())).collect::<Vec<_>>(),
+        [("getName()", Some("getName"), Some("method")), ("name", None, Some("field"))]
+    );
+    let asked = h.request("completions");
+    assert_eq!((asked["arguments"]["line"].clone(), asked["arguments"]["column"].clone()), (json!(1), json!(7)));
+    assert_eq!(asked["arguments"]["frameId"], 10);
 
     // Live breakpoint updates reach the session.
     let states = h.manager.set_breakpoints(path.clone(), vec![bp(0)]).await.unwrap();
@@ -915,6 +932,7 @@ fn godot_registry(port: u16, command: &str, args: &[&str]) -> Arc<LanguageRegist
             transport: "tcp".into(),
             connect: Some(format!("127.0.0.1:{port}")),
             install_hint: Some("Open the project in the Godot editor".into()),
+            pinned: None,
         }),
     };
     Arc::new(LanguageRegistry::from_configs(vec![lang]))
@@ -1147,3 +1165,58 @@ async fn java_stack_frames_without_breakpoints_normalize_windows_paths() {
         h.manager.stop(id).await.unwrap();
     }
 }
+
+/// A built-in language definition (GDScript) shipped by a plugin
+/// instead: its debugger starts the program approved for the plugin's
+/// `process:godot` grant, and refuses once that file changed.
+#[cfg(unix)]
+#[tokio::test]
+async fn a_plugin_language_runs_its_debug_adapter_from_the_approved_program() {
+    use ide_language::ProgramPin;
+    use ide_language::plugin_point::{PluginLanguages, parse_definition};
+    use std::os::unix::fs::PermissionsExt;
+
+    let dir = std::env::temp_dir().join(format!("openidea-plugin-dap-{}", std::process::id()));
+    std::fs::create_dir_all(&dir).unwrap();
+    // Stands in for `godot --headless --editor …`.
+    let program = dir.join("godot");
+    std::fs::write(&program, "#!/bin/sh\nexec sleep 30\n").unwrap();
+    std::fs::set_permissions(&program, std::fs::Permissions::from_mode(0o755)).unwrap();
+
+    let port = std::net::TcpListener::bind(("127.0.0.1", 0)).unwrap().local_addr().unwrap().port();
+    let mut gdscript = parse_definition(include_str!("../../../languages/gdscript.toml")).unwrap();
+    let debugger = gdscript.debugger.as_mut().unwrap();
+    debugger.args.clear();
+    debugger.connect = Some(format!("127.0.0.1:{port}"));
+
+    // No built-in GDScript: it comes from the plugin.
+    let registry = Arc::new(LanguageRegistry::from_configs(Vec::new()));
+    let store = PluginLanguages::new();
+    registry.attach_plugins(store.clone());
+    let pin = ProgramPin::approve(&program).unwrap();
+    store.set_process_policy(Arc::new(move |plugin, cap| {
+        (plugin == "acme.godot" && cap.to_string() == "process:godot").then(|| pin.clone())
+    }));
+    let _language = store.add("acme.godot".into(), gdscript);
+
+    let log: Log = Arc::default();
+    let server_log = log.clone();
+    tokio::spawn(async move {
+        tokio::time::sleep(std::time::Duration::from_millis(300)).await;
+        let listener = tokio::net::TcpListener::bind(("127.0.0.1", port)).await.unwrap();
+        let (stream, _) = listener.accept().await.unwrap();
+        fake_adapter(stream, server_log, Script::default()).await;
+    });
+    let (owner, _events) = recording_owner("main");
+    let manager = DebugManager::new(registry.clone());
+    let id = manager.start(godot_launch(&dir), owner).await.unwrap();
+    assert!(log.lock().iter().any(|m| m["command"] == "launch"));
+    manager.stop(id).await.unwrap();
+
+    // Replaced after approval: refused before anything starts.
+    std::fs::write(&program, "#!/bin/sh\nexec sleep 31\n").unwrap();
+    let (owner, _events) = recording_owner("main");
+    let err = manager.start(godot_launch(&dir), owner).await.unwrap_err();
+    assert_eq!(err.kind, ide_core::error::ErrorKind::PermissionDenied, "{}", err.message);
+    let _ = std::fs::remove_dir_all(&dir);
+}

crates/ide-extension/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "ide-extension"
+description = "Plugin manifest, extension points, contribution registry and capability model (no Wasm runtime)"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+ide-core.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+specta.workspace = true
+specta-typescript.workspace = true
+toml.workspace = true
+tracing.workspace = true
+parking_lot.workspace = true
+semver = "1"
+blake3.workspace = true
+zip.workspace = true
+base64.workspace = true
+ed25519-dalek = "3"
+
+[dev-dependencies]
+tempfile.workspace = true

crates/ide-extension/src/capability.rs

@@ -0,0 +1,277 @@
+//! What a plugin may do beyond pure computation, and how risky each grant is.
+//!
+//! Capabilities are written as strings in the manifest (`project.read`,
+//! `net:crates.io`, `process:cargo`) and stored the same way in the grant
+//! ledger. The 0.1 permission names (`project-read`, …) parse as their 0.2
+//! equivalents.
+
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+use specta::Type;
+use std::fmt;
+use std::str::FromStr;
+
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum Capability {
+    /// Read files inside the project root; the project root itself.
+    ProjectRead,
+    /// The focused editor's file, selection and text.
+    EditorRead,
+    /// Edit the focused editor (versioned edits).
+    EditorWrite,
+    VcsRead,
+    VcsWrite,
+    /// The plugin's own key-value store and data directory.
+    Storage,
+    /// The plugin's own secrets (kept in the client's OS keychain).
+    Secrets,
+    /// Workbench events (file opened, saved, focus…), not keystrokes.
+    Events,
+    /// Keystrokes and editor input events.
+    InputEvents,
+    /// The system clipboard, from the plugin's web views.
+    Clipboard,
+    /// HTTP(S) to one host (`*.example.com` matches subdomains).
+    Net(String),
+    /// Run one external program. Full code execution: never fine-grained.
+    Process(String),
+    /// Read files outside the project under one path.
+    FsRead(String),
+}
+
+/// How a grant is presented (plan 4.2).
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub enum Risk {
+    /// Listed on the install page, one confirmation.
+    Low,
+    /// Listed separately with its purpose.
+    Medium,
+    /// Separate dialog: "equivalent to running arbitrary code on this machine".
+    High,
+}
+
+impl Capability {
+    pub fn risk(&self) -> Risk {
+        match self {
+            Self::ProjectRead | Self::EditorRead | Self::Storage | Self::Events | Self::VcsRead => Risk::Low,
+            Self::EditorWrite | Self::VcsWrite | Self::Net(_) | Self::Secrets | Self::InputEvents | Self::Clipboard => {
+                Risk::Medium
+            }
+            Self::Process(_) | Self::FsRead(_) => Risk::High,
+        }
+    }
+
+    /// Low-risk capabilities that the one-time migration of the 0.1 "declared
+    /// means granted" behaviour may grant automatically (plan 4.6).
+    pub fn auto_migrates(&self) -> bool {
+        self.risk() == Risk::Low
+    }
+
+    /// Short user-facing description for install and grant pages.
+    pub fn describe(&self) -> String {
+        match self {
+            Self::ProjectRead => "Read files in the open project".into(),
+            Self::EditorRead => "Read the focused editor's file and selection".into(),
+            Self::EditorWrite => "Change text in the editor".into(),
+            Self::VcsRead => "Read version control state".into(),
+            Self::VcsWrite => "Change version control state (commit, fetch, checkout)".into(),
+            Self::Storage => "Store its own data".into(),
+            Self::Secrets => "Store secrets in the system keychain".into(),
+            Self::Events => "Observe workbench events (files opened, saved, focus)".into(),
+            Self::InputEvents => "Observe keystrokes and editor input".into(),
+            Self::Clipboard => "Read and write the clipboard from its web views".into(),
+            Self::Net(host) => format!("Connect to {host} (from the machine the project is on)"),
+            Self::Process(bin) => format!("Run {bin} — equivalent to running arbitrary code on this machine"),
+            Self::FsRead(path) => format!("Read files under {path}, outside the project"),
+        }
+    }
+
+    /// Whether `self`, granted, also covers `wanted` (`net:*.x.com` covers `net:a.x.com`).
+    pub fn covers(&self, wanted: &Capability) -> bool {
+        match (self, wanted) {
+            (Self::Net(pattern), Self::Net(host)) => host_matches(pattern, host),
+            (Self::FsRead(base), Self::FsRead(path)) => {
+                std::path::Path::new(path).starts_with(std::path::Path::new(base))
+            }
+            _ => self == wanted,
+        }
+    }
+}
+
+/// `example.com` matches exactly; `*.example.com` matches any subdomain (not the apex).
+pub fn host_matches(pattern: &str, host: &str) -> bool {
+    let host = host.trim_end_matches('.').to_ascii_lowercase();
+    let pattern = pattern.to_ascii_lowercase();
+    match pattern.strip_prefix("*.") {
+        Some(suffix) => host.len() > suffix.len() + 1 && host.ends_with(&format!(".{suffix}")),
+        None => host == pattern,
+    }
+}
+
+impl fmt::Display for Capability {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::ProjectRead => f.write_str("project.read"),
+            Self::EditorRead => f.write_str("editor.read"),
+            Self::EditorWrite => f.write_str("editor.write"),
+            Self::VcsRead => f.write_str("vcs.read"),
+            Self::VcsWrite => f.write_str("vcs.write"),
+            Self::Storage => f.write_str("storage"),
+            Self::Secrets => f.write_str("secrets"),
+            Self::Events => f.write_str("events"),
+            Self::InputEvents => f.write_str("events.input"),
+            Self::Clipboard => f.write_str("clipboard"),
+            Self::Net(h) => write!(f, "net:{h}"),
+            Self::Process(b) => write!(f, "process:{b}"),
+            Self::FsRead(p) => write!(f, "fs.read:{p}"),
+        }
+    }
+}
+
+impl FromStr for Capability {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, String> {
+        let s = s.trim();
+        if let Some((kind, arg)) = s.split_once(':') {
+            let arg = arg.trim();
+            if arg.is_empty() {
+                return Err(format!("capability {s:?} needs a value after ':'"));
+            }
+            return match kind {
+                "net" => {
+                    let host = arg.strip_prefix("*.").unwrap_or(arg);
+                    let valid = !host.is_empty()
+                        && host.len() <= 253
+                        && host.split('.').all(|label| {
+                            !label.is_empty()
+                                && label.len() <= 63
+                                && label.bytes().all(|b| b.is_ascii_alphanumeric() || b == b'-')
+                        });
+                    if valid { Ok(Self::Net(arg.to_ascii_lowercase())) } else { Err(format!("invalid host in {s:?}")) }
+                }
+                "process" => {
+                    if arg.contains(['/', '\\']) && !std::path::Path::new(arg).is_absolute() {
+                        return Err(format!("{s:?}: use a program name or an absolute path"));
+                    }
+                    Ok(Self::Process(arg.to_owned()))
+                }
+                "fs.read" => {
+                    if !std::path::Path::new(arg).is_absolute() && !arg.starts_with('~') {
+                        return Err(format!("{s:?}: use an absolute path (or ~/…)"));
+                    }
+                    Ok(Self::FsRead(arg.to_owned()))
+                }
+                _ => Err(format!("unknown capability {s:?}")),
+            };
+        }
+        Ok(match s {
+            "project.read" | "project-read" => Self::ProjectRead,
+            "editor.read" | "editor-read" => Self::EditorRead,
+            "editor.write" | "editor-write" => Self::EditorWrite,
+            "vcs.read" => Self::VcsRead,
+            "vcs.write" => Self::VcsWrite,
+            "storage" => Self::Storage,
+            "secrets" => Self::Secrets,
+            "events" => Self::Events,
+            "events.input" => Self::InputEvents,
+            "clipboard" => Self::Clipboard,
+            _ => return Err(format!("unknown capability {s:?}")),
+        })
+    }
+}
+
+impl Serialize for Capability {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        s.collect_str(self)
+    }
+}
+
+impl<'de> Deserialize<'de> for Capability {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        String::deserialize(d)?.parse().map_err(serde::de::Error::custom)
+    }
+}
+
+/// A capability as the UI shows it.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct CapabilityInfo {
+    /// `project.read`, `net:crates.io`, …
+    pub id: String,
+    pub risk: Risk,
+    pub description: String,
+    /// Declared under `optional`: the plugin runs without it.
+    pub optional: bool,
+    /// Currently granted.
+    pub granted: bool,
+}
+
+impl CapabilityInfo {
+    pub fn new(cap: &Capability, optional: bool, granted: bool) -> Self {
+        Self { id: cap.to_string(), risk: cap.risk(), description: cap.describe(), optional, granted }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_and_prints() {
+        for s in [
+            "project.read",
+            "editor.write",
+            "vcs.write",
+            "storage",
+            "secrets",
+            "events",
+            "events.input",
+            "net:crates.io",
+            "net:*.github.com",
+            "process:cargo",
+        ] {
+            assert_eq!(s.parse::<Capability>().unwrap().to_string(), s);
+        }
+        // Absolute paths are the platform's.
+        let (git, etc) = if cfg!(windows) {
+            (r"process:C:\Program Files\Git\bin\git.exe", r"fs.read:C:\Windows")
+        } else {
+            ("process:/usr/bin/git", "fs.read:/etc")
+        };
+        for s in [git, etc] {
+            assert_eq!(s.parse::<Capability>().unwrap().to_string(), s);
+        }
+        assert_eq!("project-read".parse::<Capability>().unwrap(), Capability::ProjectRead);
+        assert!("net:".parse::<Capability>().is_err());
+        assert!("net:a b".parse::<Capability>().is_err());
+        assert!("process:./evil".parse::<Capability>().is_err());
+        assert!("fs.read:rel".parse::<Capability>().is_err());
+        assert!("network".parse::<Capability>().is_err());
+    }
+
+    #[test]
+    fn risk_levels() {
+        assert_eq!(Capability::ProjectRead.risk(), Risk::Low);
+        assert_eq!(Capability::Net("x".into()).risk(), Risk::Medium);
+        assert_eq!(Capability::InputEvents.risk(), Risk::Medium);
+        assert_eq!("clipboard".parse::<Capability>().unwrap(), Capability::Clipboard);
+        assert_eq!(Capability::Clipboard.risk(), Risk::Medium);
+        assert_eq!(Capability::Process("cargo".into()).risk(), Risk::High);
+        assert!(Capability::Storage.auto_migrates() && !Capability::EditorWrite.auto_migrates());
+    }
+
+    #[test]
+    fn host_patterns() {
+        assert!(host_matches("crates.io", "crates.io"));
+        assert!(host_matches("crates.io", "CRATES.IO."));
+        assert!(!host_matches("crates.io", "static.crates.io"));
+        assert!(host_matches("*.github.com", "api.github.com"));
+        assert!(!host_matches("*.github.com", "github.com"));
+        assert!(!host_matches("*.github.com", "evilgithub.com"));
+        let any_gh: Capability = "net:*.github.com".parse().unwrap();
+        assert!(any_gh.covers(&"net:api.github.com".parse().unwrap()));
+        assert!(Capability::FsRead("/etc".into()).covers(&Capability::FsRead("/etc/hosts".into())));
+        assert!(!Capability::FsRead("/etc".into()).covers(&Capability::FsRead("/etcx".into())));
+    }
+}

crates/ide-extension/src/index.rs

@@ -0,0 +1,104 @@
+//! The contribution index: validated UI
+//! declarations of installed packages, kept on disk so start-up does not
+//! validate them again (sanitising thousands of icon SVGs, say).
+//!
+//! Only packages with a [`Package::digest`] are indexed: installed copies,
+//! which the host never modifies after install. An entry is keyed by that
+//! digest, the extension point, the declaration and a salt naming the
+//! validation logic (the IDE version), so a new package version, a changed
+//! declaration or an IDE upgrade simply misses. A miss or an unreadable entry
+//! only costs the validation.
+
+use crate::point::Package;
+use crate::ui::UiDecl;
+use std::collections::BTreeSet;
+use std::path::PathBuf;
+
+/// Bumped when [`UiDecl`]'s serialized shape changes.
+const FORMAT: u32 = 1;
+
+pub struct ContributionIndex {
+    dir: PathBuf,
+    salt: String,
+}
+
+impl ContributionIndex {
+    /// `salt` names the validators' version (the IDE version).
+    pub fn new(dir: PathBuf, salt: &str) -> Self {
+        Self { dir, salt: format!("{FORMAT}:{salt}") }
+    }
+
+    /// Entries start with a prefix of the package digest, for pruning.
+    fn file(&self, digest: &str, point: &str, decl: &toml::Value) -> PathBuf {
+        let mut h = blake3::Hasher::new();
+        for part in [self.salt.as_str(), digest, point, &decl.to_string()] {
+            h.update(part.as_bytes());
+            h.update(&[0]);
+        }
+        let key = h.finalize().to_hex();
+        self.dir.join(format!("{}-{}.json", prefix(digest), &key[..32]))
+    }
+
+    pub fn get(&self, pkg: &Package, point: &str, decl: &toml::Value) -> Option<UiDecl> {
+        let digest = pkg.digest.as_deref()?;
+        let bytes = std::fs::read(self.file(digest, point, decl)).ok()?;
+        serde_json::from_slice(&bytes).ok()
+    }
+
+    pub fn put(&self, pkg: &Package, point: &str, decl: &toml::Value, ui: &UiDecl) {
+        let Some(digest) = pkg.digest.as_deref() else { return };
+        let Ok(bytes) = serde_json::to_vec(ui) else { return };
+        let file = self.file(digest, point, decl);
+        let _ = std::fs::create_dir_all(&self.dir);
+        let tmp = file.with_extension(format!("tmp{}", std::process::id()));
+        if std::fs::write(&tmp, bytes).and_then(|()| std::fs::rename(&tmp, &file)).is_err() {
+            let _ = std::fs::remove_file(&tmp);
+        }
+    }
+
+    /// Removes entries of packages other than `live` (digests).
+    pub fn prune<'a>(&self, live: impl IntoIterator<Item = &'a str>) {
+        let keep: BTreeSet<String> = live.into_iter().map(|d| prefix(d).to_owned()).collect();
+        let Ok(entries) = std::fs::read_dir(&self.dir) else { return };
+        for e in entries.flatten() {
+            let name = e.file_name().to_string_lossy().into_owned();
+            if !name.split_once('-').is_some_and(|(p, _)| keep.contains(p)) {
+                let _ = std::fs::remove_file(e.path());
+            }
+        }
+    }
+}
+
+fn prefix(digest: &str) -> &str {
+    let d = digest.strip_prefix("blake3:").unwrap_or(digest);
+    let end = d.char_indices().nth(16).map_or(d.len(), |(i, _)| i);
+    &d[..end]
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::manifest::Manifest;
+
+    #[test]
+    fn hits_only_the_same_package_point_declaration_and_salt() {
+        let tmp = tempfile::tempdir().unwrap();
+        let index = ContributionIndex::new(tmp.path().join("idx"), "1.0");
+        let manifest =
+            Manifest::parse("id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n").unwrap();
+        let pkg = Package::new(manifest, tmp.path().to_path_buf()).with_digest("blake3:00aa11bb22cc33dd44ee");
+        let decl: toml::Value = toml::from_str("id = \"x\"").unwrap();
+        let ui = UiDecl::new("x", "X", serde_json::json!({ "id": "x" }));
+        assert!(index.get(&pkg, "pt", &decl).is_none());
+        index.put(&pkg, "pt", &decl, &ui);
+        assert_eq!(index.get(&pkg, "pt", &decl).unwrap().label, "X");
+        assert!(index.get(&pkg, "other", &decl).is_none());
+        assert!(index.get(&pkg, "pt", &toml::from_str("id = \"y\"").unwrap()).is_none());
+        assert!(ContributionIndex::new(tmp.path().join("idx"), "1.1").get(&pkg, "pt", &decl).is_none());
+        let unhashed = Package { digest: None, ..pkg.clone() };
+        assert!(index.get(&unhashed, "pt", &decl).is_none(), "not an installed copy");
+
+        index.prune(["blake3:ffff"]);
+        assert!(index.get(&pkg, "pt", &decl).is_none());
+    }
+}

crates/ide-extension/src/ledger.rs

@@ -0,0 +1,483 @@
+//! The grant ledger (plan 4.6): which capabilities the user granted to which
+//! plugin, saved as `grants.json` next to the installed plugins.
+//!
+//! - Installed plugins are keyed by id and remember the version and package
+//!   hash they were confirmed for. An update that needs no new capability is
+//!   accepted silently; one that does must be confirmed again.
+//! - Linked development plugins and project plugins (`.openidea/plugins/*`)
+//!   are keyed by their directory, not by hash, so rebuilding does not ask
+//!   again; new capabilities still do.
+//! - `process:<program>` grants record the program's absolute path and file
+//!   hash at grant time. Calls use that path, never a `PATH` lookup, and fail
+//!   when the file changed (re-confirmation needed).
+
+use crate::capability::{Capability, Risk};
+use serde::{Deserialize, Serialize};
+use std::collections::{BTreeMap, BTreeSet};
+use std::ffi::OsStr;
+use std::path::{Path, PathBuf};
+
+pub const LEDGER_FILE: &str = "grants.json";
+const FORMAT: u32 = 1;
+
+/// Whose grant an entry is.
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+#[serde(tag = "kind", content = "value", rename_all = "camelCase")]
+pub enum Subject {
+    /// Installed under the plugins directory, by plugin id.
+    Installed(String),
+    /// A linked development plugin or a project plugin, by package directory.
+    Path(PathBuf),
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct BinaryGrant {
+    pub path: PathBuf,
+    /// blake3 of the file when granted.
+    pub hash: String,
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct Grant {
+    pub plugin_id: String,
+    /// The version and package hash the user confirmed (installed plugins).
+    #[serde(default)]
+    pub version: String,
+    #[serde(default)]
+    pub package_hash: String,
+    /// The user confirmed the plugin (the install page or the project-plugin prompt).
+    #[serde(default)]
+    pub confirmed: bool,
+    /// Granted capabilities (`project.read`, `net:x`, …).
+    #[serde(default)]
+    pub granted: BTreeSet<String>,
+    /// Optional capabilities the user declined (not asked again until re-confirmed).
+    #[serde(default)]
+    pub declined: BTreeSet<String>,
+    /// `process:<program>` → the program confirmed for it.
+    #[serde(default)]
+    pub binaries: BTreeMap<String, BinaryGrant>,
+    /// Migrated from 0.1: capabilities not granted yet are asked for on first
+    /// use instead of blocking the plugin from loading.
+    #[serde(default)]
+    pub ask_on_use: bool,
+}
+
+impl Grant {
+    pub fn has(&self, cap: &Capability) -> bool {
+        self.granted.iter().filter_map(|s| s.parse::<Capability>().ok()).any(|g| g.covers(cap))
+    }
+}
+
+/// What a plugin (in its current form) needs, to compare with its grant.
+#[derive(Clone, Debug)]
+pub struct Request<'a> {
+    pub subject: Subject,
+    pub plugin_id: &'a str,
+    pub version: &'a str,
+    pub package_hash: &'a str,
+    pub required: Vec<Capability>,
+    pub optional: Vec<Capability>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum Decision {
+    /// Load with these capabilities. `pending` required ones are asked for when
+    /// the plugin is first used (plugins migrated from 0.1 only).
+    Allowed { granted: Vec<Capability>, pending: Vec<Capability> },
+    /// Ask the user first. `new` lists what was never granted (all of it on first use).
+    NeedsConfirmation { new: Vec<Capability>, first_time: bool },
+}
+
+#[derive(Debug, Default, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct File {
+    #[serde(default)]
+    format: u32,
+    /// The one-time migration from 0.1 ("declared means granted") ran.
+    #[serde(default)]
+    migrated: bool,
+    #[serde(default)]
+    grants: Vec<(Subject, Grant)>,
+}
+
+/// The ledger, loaded into memory; [`Ledger::save`] writes it atomically.
+#[derive(Debug, Default)]
+pub struct Ledger {
+    path: Option<PathBuf>,
+    migrated: bool,
+    grants: BTreeMap<Subject, Grant>,
+}
+
+impl Ledger {
+    /// Loads `<dir>/grants.json`; a missing or unreadable file gives an empty
+    /// ledger with `needs_migration()` true.
+    pub fn load(dir: &Path) -> Self {
+        let path = dir.join(LEDGER_FILE);
+        let file: Option<File> = std::fs::read_to_string(&path).ok().and_then(|s| match serde_json::from_str(&s) {
+            Ok(f) => Some(f),
+            Err(e) => {
+                tracing::warn!("{}: {e}; starting with an empty grant ledger", path.display());
+                None
+            }
+        });
+        let existed = file.is_some();
+        let file = file.unwrap_or_default();
+        Self { path: Some(path), migrated: file.migrated || existed, grants: file.grants.into_iter().collect() }
+    }
+
+    pub fn in_memory() -> Self {
+        Self { path: None, migrated: true, grants: BTreeMap::new() }
+    }
+
+    pub fn save(&self) -> std::io::Result<()> {
+        let Some(path) = &self.path else { return Ok(()) };
+        let file = File {
+            format: FORMAT,
+            migrated: self.migrated,
+            grants: self.grants.iter().map(|(s, g)| (s.clone(), g.clone())).collect(),
+        };
+        let json = serde_json::to_string_pretty(&file).map_err(std::io::Error::other)?;
+        let tmp = path.with_extension("json.tmp");
+        std::fs::write(&tmp, json)?;
+        std::fs::rename(&tmp, path)
+    }
+
+    pub fn get(&self, subject: &Subject) -> Option<&Grant> {
+        self.grants.get(subject)
+    }
+
+    pub fn remove(&mut self, subject: &Subject) -> Option<Grant> {
+        self.grants.remove(subject)
+    }
+
+    /// Puts back an earlier state of `subject`'s grant (`None`: none), e.g.
+    /// after rolling back an update.
+    pub fn restore(&mut self, subject: &Subject, grant: Option<Grant>) {
+        match grant {
+            Some(g) => {
+                self.grants.insert(subject.clone(), g);
+            }
+            None => {
+                self.grants.remove(subject);
+            }
+        }
+    }
+
+    /// The one-time migration of 0.1's "declared means granted" has not run yet.
+    pub fn needs_migration(&self) -> bool {
+        !self.migrated
+    }
+
+    /// Migrates plugins installed before the ledger existed: low-risk
+    /// capabilities are granted, the rest are asked on first use.
+    pub fn migrate(&mut self, installed: &[Request<'_>]) {
+        for req in installed {
+            let granted: BTreeSet<String> =
+                req.required.iter().chain(&req.optional).filter(|c| c.auto_migrates()).map(|c| c.to_string()).collect();
+            self.grants.entry(req.subject.clone()).or_insert_with(|| Grant {
+                plugin_id: req.plugin_id.to_owned(),
+                version: req.version.to_owned(),
+                package_hash: req.package_hash.to_owned(),
+                confirmed: true,
+                granted,
+                ask_on_use: true,
+                ..Grant::default()
+            });
+        }
+        self.migrated = true;
+    }
+
+    /// Compares what the plugin needs with what was granted.
+    pub fn decide(&mut self, req: &Request<'_>) -> Decision {
+        let Some(grant) = self.grants.get_mut(&req.subject) else {
+            return Decision::NeedsConfirmation { new: req.required.clone(), first_time: true };
+        };
+        if !grant.confirmed {
+            return Decision::NeedsConfirmation { new: req.required.clone(), first_time: true };
+        }
+        let new: Vec<Capability> = req.required.iter().filter(|c| !grant.has(c)).cloned().collect();
+        if !new.is_empty() && !grant.ask_on_use {
+            return Decision::NeedsConfirmation { new, first_time: false };
+        }
+        // Same or fewer needs: accept an update silently (plan 4.6).
+        if grant.version != req.version || grant.package_hash != req.package_hash {
+            grant.version = req.version.to_owned();
+            grant.package_hash = req.package_hash.to_owned();
+        }
+        let granted = req.required.iter().chain(&req.optional).filter(|c| grant.has(c)).cloned().collect();
+        Decision::Allowed { granted, pending: new }
+    }
+
+    /// Records the user's confirmation: `required` plus the accepted optional capabilities.
+    pub fn confirm(
+        &mut self,
+        req: &Request<'_>,
+        accepted_optional: &[Capability],
+        binaries: BTreeMap<String, BinaryGrant>,
+    ) {
+        let grant = self.grants.entry(req.subject.clone()).or_default();
+        grant.plugin_id = req.plugin_id.to_owned();
+        grant.version = req.version.to_owned();
+        grant.package_hash = req.package_hash.to_owned();
+        grant.confirmed = true;
+        grant.ask_on_use = false;
+        for cap in req.required.iter().chain(accepted_optional) {
+            grant.granted.insert(cap.to_string());
+        }
+        for cap in &req.optional {
+            let s = cap.to_string();
+            if accepted_optional.contains(cap) {
+                grant.declined.remove(&s);
+            } else if !grant.granted.contains(&s) {
+                grant.declined.insert(s);
+            }
+        }
+        grant.binaries.extend(binaries);
+    }
+
+    /// Grants or revokes one capability (Settings › Plugins › permissions).
+    pub fn set(&mut self, subject: &Subject, cap: &Capability, granted: bool) -> bool {
+        let Some(grant) = self.grants.get_mut(subject) else { return false };
+        let s = cap.to_string();
+        if granted {
+            grant.declined.remove(&s);
+            grant.granted.insert(s)
+        } else {
+            if let Capability::Process(_) = cap {
+                grant.binaries.remove(&s);
+            }
+            grant.granted.remove(&s)
+        }
+    }
+
+    /// Records the program approved for a `process:` grant.
+    pub fn set_binary(&mut self, subject: &Subject, cap: &Capability, binary: BinaryGrant) {
+        if let Some(grant) = self.grants.get_mut(subject) {
+            grant.binaries.insert(cap.to_string(), binary);
+        }
+    }
+
+    /// Checks a `process:` grant at call time: the program confirmed for it,
+    /// unchanged since. Errors name what to do.
+    pub fn check_binary(&self, subject: &Subject, cap: &Capability) -> Result<PathBuf, String> {
+        let Capability::Process(name) = cap else { return Err(format!("{cap} is not a process capability")) };
+        let grant = self.grants.get(subject).ok_or_else(|| format!("{cap} was not granted"))?;
+        let key = cap.to_string();
+        if !grant.granted.contains(&key) {
+            return Err(format!("{cap} was not granted"));
+        }
+        let bin = grant.binaries.get(&key).ok_or_else(|| format!("{cap}: no program was confirmed for {name}"))?;
+        match file_hash(&bin.path) {
+            Ok(hash) if hash == bin.hash => Ok(bin.path.clone()),
+            Ok(_) => Err(format!(
+                "{} changed since it was approved for {cap}; confirm the plugin's permissions again",
+                bin.path.display()
+            )),
+            Err(e) => Err(format!("{}: {e}; confirm the plugin's permissions again", bin.path.display())),
+        }
+    }
+
+    /// The program approved for a granted `process:` capability, without
+    /// checking the file: whoever starts it verifies the hash then
+    /// ([`check_binary`](Self::check_binary) or the pin's own check).
+    pub fn pinned_binary(&self, subject: &Subject, cap: &Capability) -> Option<BinaryGrant> {
+        let grant = self.grants.get(subject)?;
+        let key = cap.to_string();
+        if !grant.granted.contains(&key) {
+            return None;
+        }
+        grant.binaries.get(&key).cloned()
+    }
+
+    pub fn subjects(&self) -> impl Iterator<Item = (&Subject, &Grant)> {
+        self.grants.iter()
+    }
+}
+
+/// What a confirmation page shows: every capability with its risk, high risk first.
+pub fn by_risk(caps: &[Capability]) -> Vec<(Risk, Vec<Capability>)> {
+    let mut groups: BTreeMap<std::cmp::Reverse<Risk>, Vec<Capability>> = BTreeMap::new();
+    for c in caps {
+        groups.entry(std::cmp::Reverse(c.risk())).or_default().push(c.clone());
+    }
+    groups.into_iter().map(|(r, v)| (r.0, v)).collect()
+}
+
+/// Resolves a `process:` program to an absolute path once, at grant time:
+/// absolute names are taken as is, others are looked up in `path_var`.
+pub fn resolve_program(name: &str, path_var: Option<&OsStr>) -> Result<PathBuf, String> {
+    let candidate = Path::new(name);
+    if candidate.is_absolute() {
+        return if candidate.is_file() { Ok(candidate.to_path_buf()) } else { Err(format!("{name}: no such program")) };
+    }
+    let exts: Vec<String> = if cfg!(windows) {
+        std::env::var("PATHEXT").unwrap_or_else(|_| ".EXE;.CMD;.BAT".into()).split(';').map(str::to_owned).collect()
+    } else {
+        vec![String::new()]
+    };
+    for dir in std::env::split_paths(path_var.unwrap_or_default()) {
+        if !dir.is_absolute() {
+            continue; // `.` or relative entries could point into the project
+        }
+        for ext in &exts {
+            let p = dir.join(format!("{name}{ext}"));
+            if is_executable(&p) {
+                return Ok(dunce_canonical(&p));
+            }
+        }
+    }
+    Err(format!("{name} was not found on PATH"))
+}
+
+fn dunce_canonical(p: &Path) -> PathBuf {
+    std::fs::canonicalize(p).unwrap_or_else(|_| p.to_path_buf())
+}
+
+fn is_executable(p: &Path) -> bool {
+    let Ok(meta) = std::fs::metadata(p) else { return false };
+    if !meta.is_file() {
+        return false;
+    }
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        meta.permissions().mode() & 0o111 != 0
+    }
+    #[cfg(not(unix))]
+    true
+}
+
+/// blake3 of a file, hex.
+pub fn file_hash(path: &Path) -> std::io::Result<String> {
+    let mut hasher = blake3::Hasher::new();
+    hasher.update_reader(std::fs::File::open(path)?)?;
+    Ok(hasher.finalize().to_hex().to_string())
+}
+
+/// blake3 over a package's files (sorted relative paths and contents).
+pub fn package_hash(dir: &Path, files: &[PathBuf]) -> std::io::Result<String> {
+    let mut sorted: Vec<&PathBuf> = files.iter().collect();
+    sorted.sort();
+    sorted.dedup();
+    let mut hasher = blake3::Hasher::new();
+    for rel in sorted {
+        hasher.update(rel.to_string_lossy().as_bytes());
+        hasher.update(&[0]);
+        hasher.update_reader(std::fs::File::open(dir.join(rel))?)?;
+        hasher.update(&[0]);
+    }
+    Ok(hasher.finalize().to_hex().to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn caps(list: &[&str]) -> Vec<Capability> {
+        list.iter().map(|s| s.parse().unwrap()).collect()
+    }
+
+    fn req<'a>(version: &'a str, hash: &'a str, required: &[&str], optional: &[&str]) -> Request<'a> {
+        Request {
+            subject: Subject::Installed("p".into()),
+            plugin_id: "p",
+            version,
+            package_hash: hash,
+            required: caps(required),
+            optional: caps(optional),
+        }
+    }
+
+    #[test]
+    fn confirmation_then_silent_update_then_reconfirm_on_new_capability() {
+        let mut l = Ledger::in_memory();
+        let r1 = req("1.0.0", "h1", &["project.read"], &["net:crates.io"]);
+        assert_eq!(l.decide(&r1), Decision::NeedsConfirmation { new: caps(&["project.read"]), first_time: true });
+        l.confirm(&r1, &[], BTreeMap::new());
+        assert_eq!(
+            l.decide(&r1),
+            Decision::Allowed { granted: caps(&["project.read"]), pending: vec![] },
+            "declined optional"
+        );
+        assert!(l.get(&r1.subject).unwrap().declined.contains("net:crates.io"));
+
+        // Same needs, new version: silent.
+        let r2 = req("1.1.0", "h2", &["project.read"], &["net:crates.io"]);
+        assert!(matches!(l.decide(&r2), Decision::Allowed { .. }));
+        assert_eq!(l.get(&r2.subject).unwrap().version, "1.1.0");
+
+        // A new required capability: ask again, only for it.
+        let r3 = req("1.2.0", "h3", &["project.read", "editor.write"], &[]);
+        assert_eq!(l.decide(&r3), Decision::NeedsConfirmation { new: caps(&["editor.write"]), first_time: false });
+        l.confirm(&r3, &[], BTreeMap::new());
+        assert!(matches!(l.decide(&r3), Decision::Allowed { .. }));
+
+        // Revoking a required capability blocks loading again.
+        assert!(l.set(&r3.subject, &Capability::EditorWrite, false));
+        assert!(matches!(l.decide(&r3), Decision::NeedsConfirmation { .. }));
+    }
+
+    #[test]
+    fn migration_grants_low_risk_only() {
+        let tmp = tempfile::tempdir().unwrap();
+        let mut l = Ledger::load(tmp.path());
+        assert!(l.needs_migration());
+        let r = req("0.1.0", "h", &["project.read", "editor.write"], &[]);
+        l.migrate(std::slice::from_ref(&r));
+        // Loads with the low-risk part; the rest is asked for on first use.
+        assert_eq!(
+            l.decide(&r),
+            Decision::Allowed { granted: caps(&["project.read"]), pending: caps(&["editor.write"]) }
+        );
+        l.confirm(&r, &[], BTreeMap::new());
+        assert_eq!(
+            l.decide(&r),
+            Decision::Allowed { granted: caps(&["project.read", "editor.write"]), pending: vec![] }
+        );
+        l.save().unwrap();
+        let again = Ledger::load(tmp.path());
+        assert!(!again.needs_migration());
+        assert!(again.get(&r.subject).unwrap().has(&Capability::ProjectRead));
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn binaries_are_pinned_by_path_and_hash() {
+        use std::os::unix::fs::PermissionsExt;
+        let tmp = tempfile::tempdir().unwrap();
+        let bin_dir = tmp.path().join("bin");
+        std::fs::create_dir(&bin_dir).unwrap();
+        let tool = bin_dir.join("tool");
+        std::fs::write(&tool, "#!/bin/sh\necho v1\n").unwrap();
+        std::fs::set_permissions(&tool, std::fs::Permissions::from_mode(0o755)).unwrap();
+        let path_var = std::env::join_paths([PathBuf::from("relative"), bin_dir.clone()]).unwrap();
+        let resolved = resolve_program("tool", Some(&path_var)).unwrap();
+        assert!(resolved.is_absolute());
+        assert!(resolve_program("missing", Some(&path_var)).is_err());
+
+        let mut l = Ledger::in_memory();
+        let r = req("1.0.0", "h", &["process:tool"], &[]);
+        let cap: Capability = "process:tool".parse().unwrap();
+        let bin = BinaryGrant { path: resolved.clone(), hash: file_hash(&resolved).unwrap() };
+        l.confirm(&r, &[], [(cap.to_string(), bin)].into());
+        assert_eq!(l.check_binary(&r.subject, &cap).unwrap(), resolved);
+        std::fs::write(&tool, "#!/bin/sh\necho evil\n").unwrap();
+        assert!(l.check_binary(&r.subject, &cap).unwrap_err().contains("changed"));
+    }
+
+    #[test]
+    fn hashes_and_grouping() {
+        let tmp = tempfile::tempdir().unwrap();
+        std::fs::write(tmp.path().join("a"), "1").unwrap();
+        std::fs::write(tmp.path().join("b"), "2").unwrap();
+        let h1 = package_hash(tmp.path(), &["a".into(), "b".into()]).unwrap();
+        assert_eq!(h1, package_hash(tmp.path(), &["b".into(), "a".into()]).unwrap());
+        std::fs::write(tmp.path().join("b"), "3").unwrap();
+        assert_ne!(h1, package_hash(tmp.path(), &["a".into(), "b".into()]).unwrap());
+        let groups = by_risk(&caps(&["storage", "process:git", "net:x.io"]));
+        assert_eq!(groups.iter().map(|g| g.0).collect::<Vec<_>>(), [Risk::High, Risk::Medium, Risk::Low]);
+    }
+}

crates/ide-extension/src/lib.rs

@@ -0,0 +1,36 @@
+//! The plugin system's kernel, independent of the Wasm runtime:
+//!
+//! - [`Manifest`]: `plugin.toml` (0.2 format; 0.1 still parses);
+//! - [`Capability`]: what a plugin may do, with its [`Risk`] level;
+//! - [`ExtensionPoint`]: one kind of contribution, implemented by the crate that
+//!   owns the feature; [`ExtensionRegistry`] validates a package's declarations
+//!   ([`ExtensionRegistry::prepare`], no side effects), makes them take effect
+//!   all or nothing ([`ExtensionRegistry::commit`]) and withdraws them per plugin;
+//! - [`UiStore`] / [`UiPoint`]: UI contributions, validated here and projected
+//!   by the client without the possibility to fail;
+//! - [`ledger`]: which capabilities the user granted to which plugin;
+//! - [`package`]: the package file, its signature and the marketplace index.
+//!
+//! Dependency direction: `ide-core` ← `ide-extension` ← feature crates (their
+//! extension points) and `ide-plugin` (Wasm) ← `ide-host` (assembly).
+
+mod capability;
+mod index;
+pub mod ledger;
+mod manifest;
+pub mod package;
+mod point;
+mod registry;
+mod ui;
+mod when;
+
+pub use capability::{Capability, CapabilityInfo, Risk, host_matches};
+pub use index::ContributionIndex;
+pub use manifest::{
+    ActivationEvent, Capabilities, ENGINE_VERSION, EVENT_KINDS, LEGACY_API, MANIFEST_FILE, Manifest, check_relative,
+    engine_compatible, validate_item_id, validate_plugin_id, validate_point_id,
+};
+pub use point::{Commit, Disposable, ExtensionPoint, MAX_PACKAGE_FILE, Package, Placement, Prepared, decode};
+pub use registry::{ContributionInfo, ExtensionRegistry, PreparedSet};
+pub use ui::{UiContribution, UiDecl, UiPoint, UiStore, to_json};
+pub use when::validate_when;

crates/ide-extension/src/manifest.rs

@@ -0,0 +1,501 @@
+//! `plugin.toml`, the package manifest (plan 4.4).
+//!
+//! ```toml
+//! id = "acme.rust-tools"          # optional publisher namespace before the first '.'
+//! name = "Rust Tools"
+//! version = "1.2.0"
+//! engines.openidea = "^1.0"
+//! wasm = "plugin.wasm"
+//! activation = ["on-language:rust", "on-command:check"]
+//!
+//! [capabilities]
+//! required = ["project.read", "editor.write"]
+//! optional = ["net:crates.io", "process:cargo"]
+//!
+//! [[contributes.commands]]
+//! id = "check"
+//! title = "Check"
+//! ```
+//!
+//! `contributes` is kept as raw TOML: each `contributes.<point>` is parsed and
+//! validated by the extension point registered under that id
+//! ([`crate::ExtensionRegistry`]), so new contribution types need no change here.
+//!
+//! Manifests in the 0.1 format (`openidea-api = "0.1"`, `permissions = [...]`)
+//! still parse: permissions become required capabilities and the plugin is
+//! activated at start-up, as before.
+
+use crate::capability::Capability;
+use serde::Deserialize;
+use std::collections::BTreeSet;
+use std::path::{Component, Path, PathBuf};
+
+pub const MANIFEST_FILE: &str = "plugin.toml";
+/// The plugin API (engine) version this host implements.
+pub const ENGINE_VERSION: &str = "1.0.0";
+/// The 0.1 API, still accepted for contribution-only packages and 0.1 components.
+pub const LEGACY_API: &str = "0.1";
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Manifest {
+    pub id: String,
+    pub name: String,
+    pub version: String,
+    pub description: String,
+    pub authors: Vec<String>,
+    pub homepage: Option<String>,
+    pub license: Option<String>,
+    /// Release notes of this version (Settings › Plugins › What's New).
+    pub change_notes: Option<String>,
+    /// `engines.openidea` (a semver requirement), or the legacy `openidea-api`.
+    pub engine: String,
+    /// Written in the 0.1 format.
+    pub legacy: bool,
+    /// Component file relative to the package directory.
+    pub wasm: Option<PathBuf>,
+    pub activation: Vec<ActivationEvent>,
+    pub capabilities: Capabilities,
+    /// `contributes.<point>` → its declarations, validated by the extension points.
+    pub contributes: toml::Table,
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub struct Capabilities {
+    pub required: Vec<Capability>,
+    pub optional: Vec<Capability>,
+}
+
+impl Capabilities {
+    pub fn all(&self) -> impl Iterator<Item = &Capability> {
+        self.required.iter().chain(&self.optional)
+    }
+
+    pub fn is_optional(&self, cap: &Capability) -> bool {
+        self.optional.contains(cap) && !self.required.contains(cap)
+    }
+}
+
+/// When a plugin's code is instantiated (plan 4.4). Contributions are live
+/// without it; code only runs once one of these fires.
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum ActivationEvent {
+    /// One of the plugin's commands is run (`on-command:<id>`; `*` = any).
+    Command(String),
+    /// A file of this language is opened.
+    Language(String),
+    /// A file matching this glob (project-relative) is opened.
+    File(String),
+    /// One of the plugin's views is shown.
+    View(String),
+    /// Periodically: `on-schedule:<seconds>`. Does not keep the plugin alive.
+    Schedule(u32),
+    /// A workbench event of this kind (`on-event:file-saved`): the plugin is
+    /// subscribed from the start, and activated to receive it.
+    Event(String),
+    /// Shortly after the workbench is ready.
+    StartupFinished,
+}
+
+impl ActivationEvent {
+    pub fn parse(s: &str) -> Result<Self, String> {
+        let s = s.trim();
+        if s == "on-startup-finished" {
+            return Ok(Self::StartupFinished);
+        }
+        let (kind, arg) = s.split_once(':').ok_or_else(|| format!("unknown activation event {s:?}"))?;
+        let arg = arg.trim();
+        if arg.is_empty() {
+            return Err(format!("activation event {s:?} needs a value"));
+        }
+        Ok(match kind {
+            "on-command" => Self::Command(arg.into()),
+            "on-language" => Self::Language(arg.into()),
+            "on-file" => Self::File(arg.into()),
+            "on-view" => Self::View(arg.into()),
+            "on-schedule" => {
+                let secs: u32 =
+                    arg.trim_end_matches('s').parse().map_err(|_| format!("{s:?}: expected seconds, e.g. 300"))?;
+                if secs < 60 {
+                    return Err(format!("{s:?}: the shortest schedule is 60 seconds"));
+                }
+                Self::Schedule(secs)
+            }
+            "on-event" => {
+                if !EVENT_KINDS.contains(&arg) {
+                    return Err(format!("{s:?}: unknown event kind (one of {})", EVENT_KINDS.join(", ")));
+                }
+                Self::Event(arg.into())
+            }
+            _ => return Err(format!("unknown activation event {s:?}")),
+        })
+    }
+}
+
+/// Workbench event kinds (`on-event:<kind>`, WIT `events.event-kind`).
+/// `scheduled` comes from `on-schedule` instead.
+pub const EVENT_KINDS: &[&str] = &["file-opened", "file-saved", "editor-focused", "action-performed", "vcs-changed"];
+
+impl std::fmt::Display for ActivationEvent {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Command(c) => write!(f, "on-command:{c}"),
+            Self::Language(l) => write!(f, "on-language:{l}"),
+            Self::File(g) => write!(f, "on-file:{g}"),
+            Self::View(v) => write!(f, "on-view:{v}"),
+            Self::Schedule(s) => write!(f, "on-schedule:{s}"),
+            Self::Event(k) => write!(f, "on-event:{k}"),
+            Self::StartupFinished => f.write_str("on-startup-finished"),
+        }
+    }
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "kebab-case", deny_unknown_fields)]
+struct Raw {
+    id: String,
+    name: String,
+    version: String,
+    #[serde(default)]
+    description: String,
+    #[serde(default)]
+    authors: Vec<String>,
+    #[serde(default)]
+    homepage: Option<String>,
+    #[serde(default)]
+    license: Option<String>,
+    #[serde(default)]
+    change_notes: Option<String>,
+    #[serde(default)]
+    engines: Option<Engines>,
+    /// 0.1 format.
+    #[serde(default)]
+    openidea_api: Option<String>,
+    #[serde(default)]
+    wasm: Option<PathBuf>,
+    #[serde(default)]
+    activation: Option<Vec<String>>,
+    #[serde(default)]
+    capabilities: Option<RawCapabilities>,
+    /// 0.1 format.
+    #[serde(default)]
+    permissions: Option<Vec<String>>,
+    #[serde(default)]
+    contributes: toml::Table,
+}
+
+#[derive(Deserialize)]
+#[serde(deny_unknown_fields)]
+struct Engines {
+    openidea: String,
+}
+
+#[derive(Deserialize)]
+#[serde(deny_unknown_fields)]
+struct RawCapabilities {
+    #[serde(default)]
+    required: Vec<String>,
+    #[serde(default)]
+    optional: Vec<String>,
+}
+
+impl Manifest {
+    pub fn parse(src: &str) -> Result<Self, String> {
+        let raw: Raw = toml::from_str(src).map_err(|e| e.to_string())?;
+        let (engine, legacy) = match (raw.engines, raw.openidea_api) {
+            (Some(e), None) => (e.openidea, false),
+            (None, Some(api)) => (api, true),
+            (Some(_), Some(_)) => return Err("use `engines.openidea`, not `openidea-api`".into()),
+            (None, None) => return Err("missing `engines.openidea` (e.g. \"^1.0\")".into()),
+        };
+        if legacy && raw.capabilities.is_some() {
+            return Err("`capabilities` requires `engines.openidea`; 0.1 manifests use `permissions`".into());
+        }
+        if !legacy && raw.permissions.is_some() {
+            return Err("`permissions` is the 0.1 format; use `[capabilities] required = [...]`".into());
+        }
+        let parse_caps = |list: Vec<String>| -> Result<Vec<Capability>, String> {
+            let mut out: Vec<Capability> = Vec::new();
+            for s in list {
+                let cap: Capability = s.parse()?;
+                if !out.contains(&cap) {
+                    out.push(cap);
+                }
+            }
+            Ok(out)
+        };
+        let capabilities = match (raw.capabilities, raw.permissions) {
+            (Some(c), _) => Capabilities { required: parse_caps(c.required)?, optional: parse_caps(c.optional)? },
+            (None, Some(p)) => Capabilities { required: parse_caps(p)?, optional: Vec::new() },
+            (None, None) => Capabilities::default(),
+        };
+        let activation = match raw.activation {
+            Some(list) => list.iter().map(|s| ActivationEvent::parse(s)).collect::<Result<Vec<_>, _>>()?,
+            // 0.1 plugins were activated at start-up; keep that until they move to 1.0.
+            None if legacy && raw.wasm.is_some() => vec![ActivationEvent::StartupFinished],
+            None => Vec::new(),
+        };
+        let m = Manifest {
+            id: raw.id,
+            name: raw.name,
+            version: raw.version,
+            description: raw.description,
+            authors: raw.authors,
+            homepage: raw.homepage,
+            license: raw.license,
+            change_notes: raw.change_notes,
+            engine,
+            legacy,
+            wasm: raw.wasm,
+            activation,
+            capabilities,
+            contributes: raw.contributes,
+        };
+        m.validate()?;
+        Ok(m)
+    }
+
+    pub fn load(dir: &Path) -> Result<Self, String> {
+        let path = dir.join(MANIFEST_FILE);
+        let src = std::fs::read_to_string(&path).map_err(|e| format!("{}: {e}", path.display()))?;
+        Self::parse(&src).map_err(|e| format!("{}: {e}", path.display()))
+    }
+
+    fn validate(&self) -> Result<(), String> {
+        validate_plugin_id(&self.id)?;
+        if self.name.trim().is_empty() {
+            return Err("`name` must not be empty".into());
+        }
+        if semver::Version::parse(&self.version).is_err() {
+            return Err(format!("`version` must be a semantic version like 1.2.3, got {:?}", self.version));
+        }
+        if !engine_compatible(&self.engine, self.legacy) {
+            return Err(if self.legacy {
+                format!(
+                    "unsupported openidea-api {:?} (this IDE implements {LEGACY_API} and {ENGINE_VERSION})",
+                    self.engine
+                )
+            } else {
+                format!("engines.openidea {:?} does not match this IDE's plugin API {ENGINE_VERSION}", self.engine)
+            });
+        }
+        if let Some(wasm) = &self.wasm {
+            check_relative(wasm, "wasm")?;
+        }
+        if self.wasm.is_none() && !self.activation.is_empty() {
+            return Err("`activation` needs `wasm`: there is no code to activate".into());
+        }
+        let mut seen = BTreeSet::new();
+        for event in &self.activation {
+            if !seen.insert(event) {
+                return Err(format!("duplicate activation event {event}"));
+            }
+        }
+        for (point, decls) in &self.contributes {
+            validate_point_id(point)?;
+            if !matches!(decls, toml::Value::Array(_) | toml::Value::Table(_)) {
+                return Err(format!("`contributes.{point}` must be a table or an array of tables"));
+            }
+        }
+        Ok(())
+    }
+
+    /// The declarations of one extension point: `[[contributes.x]]` gives
+    /// several, `[contributes.x]` one.
+    pub fn declarations(&self, point: &str) -> Vec<toml::Value> {
+        match self.contributes.get(point) {
+            Some(toml::Value::Array(items)) => items.clone(),
+            Some(single @ toml::Value::Table(_)) => vec![single.clone()],
+            _ => Vec::new(),
+        }
+    }
+
+    /// Number of declarations per extension point (for listings before loading).
+    pub fn declaration_counts(&self) -> Vec<(String, u32)> {
+        self.contributes.keys().map(|p| (p.clone(), self.declarations(p).len() as u32)).collect()
+    }
+
+    /// Publisher namespace: the id's part before the first `.` (`acme` in `acme.tools`).
+    pub fn publisher(&self) -> Option<&str> {
+        self.id.split_once('.').map(|(p, _)| p)
+    }
+
+    /// Whether `cap` is declared (required or optional).
+    pub fn declares(&self, cap: &Capability) -> bool {
+        self.capabilities.all().any(|c| c.covers(cap))
+    }
+}
+
+/// Whether this host can load a plugin written for `engine`.
+pub fn engine_compatible(engine: &str, legacy: bool) -> bool {
+    if legacy {
+        return engine == LEGACY_API || engine.strip_prefix(LEGACY_API).is_some_and(|rest| rest.starts_with('.'));
+    }
+    let Ok(req) = semver::VersionReq::parse(engine) else { return false };
+    let host = semver::Version::parse(ENGINE_VERSION).expect("valid engine version");
+    req.matches(&host)
+}
+
+/// Segments of `[a-z0-9][a-z0-9_-]*` joined by `.` (an optional publisher
+/// namespace first), at most 64 chars.
+pub fn validate_plugin_id(id: &str) -> Result<(), String> {
+    let ok = id.len() <= 64 && !id.is_empty() && id.split('.').all(segment_ok);
+    if ok {
+        Ok(())
+    } else {
+        Err(format!(
+            "invalid plugin id {id:?}: use a-z, 0-9, '-', '_' in '.'-separated parts (e.g. acme.tools), max 64"
+        ))
+    }
+}
+
+/// `[a-z0-9][a-z0-9._-]*`, at most 64 chars (commands, themes, views…).
+pub fn validate_item_id(id: &str, what: &str) -> Result<(), String> {
+    let ok_first = id.chars().next().is_some_and(|c| c.is_ascii_lowercase() || c.is_ascii_digit());
+    let ok_rest = id.chars().all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || matches!(c, '-' | '_' | '.'));
+    if ok_first && ok_rest && id.len() <= 64 {
+        Ok(())
+    } else {
+        Err(format!("invalid {what} {id:?}: use a-z, 0-9, '.', '-', '_', starting with a letter or digit (max 64)"))
+    }
+}
+
+/// Extension point ids: `camelCase` or `kebab-case` words, dots allowed (`iconThemes`, `menus`).
+pub fn validate_point_id(id: &str) -> Result<(), String> {
+    let ok = !id.is_empty()
+        && id.len() <= 64
+        && id.starts_with(|c: char| c.is_ascii_lowercase())
+        && id.chars().all(|c| c.is_ascii_alphanumeric() || matches!(c, '-' | '.'));
+    if ok { Ok(()) } else { Err(format!("invalid contribution point {id:?}")) }
+}
+
+fn segment_ok(s: &str) -> bool {
+    s.chars().next().is_some_and(|c| c.is_ascii_lowercase() || c.is_ascii_digit())
+        && s.chars().all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || c == '-' || c == '_')
+}
+
+/// Package paths must stay inside the package directory.
+pub fn check_relative(path: &Path, what: &str) -> Result<(), String> {
+    let ok = !path.as_os_str().is_empty() && path.components().all(|c| matches!(c, Component::Normal(_)));
+    if ok { Ok(()) } else { Err(format!("{what} {:?} must be a relative path inside the plugin", path.display())) }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const FULL: &str = r#"
+        id = "acme.rust-tools"
+        name = "Rust Tools"
+        version = "1.2.0"
+        engines.openidea = "^1.0"
+        wasm = "plugin.wasm"
+        activation = ["on-language:rust", "on-command:check", "on-schedule:300"]
+
+        [capabilities]
+        required = ["project.read", "editor.write"]
+        optional = ["net:crates.io", "process:cargo"]
+
+        [[contributes.commands]]
+        id = "check"
+        title = "%check.title%"
+
+        [[contributes.menus]]
+        menu = "editor.context"
+        command = "check"
+        when = "editorLang == rust"
+
+        [contributes.settings]
+        schema = "settings.schema.json"
+    "#;
+
+    #[test]
+    fn event_activation() {
+        assert_eq!(ActivationEvent::parse("on-event:file-saved"), Ok(ActivationEvent::Event("file-saved".into())));
+        assert_eq!(ActivationEvent::Event("vcs-changed".into()).to_string(), "on-event:vcs-changed");
+        let err = ActivationEvent::parse("on-event:keystroke").unwrap_err();
+        assert!(err.contains("unknown event kind") && err.contains("action-performed"), "{err}");
+        assert!(ActivationEvent::parse("on-event:scheduled").is_err(), "declared with on-schedule");
+    }
+
+    #[test]
+    fn parses_the_02_format() {
+        let m = Manifest::parse(FULL).unwrap();
+        assert_eq!(m.publisher(), Some("acme"));
+        assert!(!m.legacy);
+        assert_eq!(m.activation.len(), 3);
+        assert_eq!(m.activation[2], ActivationEvent::Schedule(300));
+        assert_eq!(m.capabilities.required, vec![Capability::ProjectRead, Capability::EditorWrite]);
+        assert!(m.capabilities.is_optional(&Capability::Process("cargo".into())));
+        assert_eq!(m.declarations("commands").len(), 1);
+        assert_eq!(m.declarations("settings").len(), 1, "a single table is one declaration");
+        assert!(m.declarations("nope").is_empty());
+        let counts: Vec<_> = m.declaration_counts();
+        assert!(counts.contains(&("menus".into(), 1)));
+    }
+
+    #[test]
+    fn parses_the_01_format() {
+        let m = Manifest::parse(
+            "id = \"hello\"\nname = \"Hello\"\nversion = \"0.1.0\"\nopenidea-api = \"0.1\"\nwasm = \"dist/plugin.wasm\"\n\
+             permissions = [\"project-read\", \"editor-write\"]\n[[contributes.commands]]\nid = \"x\"\ntitle = \"X\"",
+        )
+        .unwrap();
+        assert!(m.legacy);
+        assert_eq!(m.capabilities.required, vec![Capability::ProjectRead, Capability::EditorWrite]);
+        assert_eq!(m.activation, vec![ActivationEvent::StartupFinished]);
+        assert_eq!(m.publisher(), None);
+    }
+
+    fn err(src: &str) -> String {
+        Manifest::parse(src).unwrap_err()
+    }
+
+    #[test]
+    fn rejects_invalid_manifests() {
+        let base = |extra: &str| format!("id = \"ok\"\nname = \"N\"\nversion = \"1.0.0\"\n{extra}");
+        assert!(err(&base("")).contains("engines.openidea"));
+        assert!(err(&base("engines.openidea = \"^0.3\"")).contains("does not match"));
+        assert!(err(&base("engines.openidea = \"^2\"")).contains("does not match"));
+        assert!(err(&base("engines.openidea = \"^0.2\"")).contains("does not match"));
+        assert!(err(&base("openidea-api = \"0.2\"")).contains("unsupported"));
+        assert!(err(&base("engines.openidea = \"^1.0\"\npermissions = [\"project-read\"]")).contains("0.1 format"));
+        assert!(
+            err(&base("engines.openidea = \"^1.0\"\n[capabilities]\nrequired = [\"network\"]")).contains("unknown")
+        );
+        assert!(err(&base("engines.openidea = \"^1.0\"\nwasm = \"../x.wasm\"")).contains("relative path"));
+        assert!(err(&base("engines.openidea = \"^1.0\"\nactivation = [\"on-command:x\"]")).contains("needs `wasm`"));
+        assert!(
+            err(&base("engines.openidea = \"^1.0\"\nwasm = \"p.wasm\"\nactivation = [\"on-boot\"]"))
+                .contains("unknown")
+        );
+        assert!(
+            err(&base("engines.openidea = \"^1.0\"\nwasm = \"p.wasm\"\nactivation = [\"on-schedule:5\"]"))
+                .contains("60 seconds")
+        );
+        assert!(err(&base("engines.openidea = \"^1.0\"\nbogus = 1")).contains("unknown field"));
+        assert!(err(&base("engines.openidea = \"^1.0\"\ncontributes.commands = 3")).contains("table"));
+        assert!(
+            err("id = \"Bad\"\nname = \"N\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"").contains("plugin id")
+        );
+        assert!(
+            err("id = \"a..b\"\nname = \"N\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"").contains("plugin id")
+        );
+        assert!(err("id = \"ok\"\nname = \"N\"\nversion = \"1.0\"\nengines.openidea = \"^1.0\"").contains("version"));
+    }
+
+    #[test]
+    fn ids() {
+        assert!(validate_plugin_id("openidea.material-icons").is_ok());
+        assert!(validate_plugin_id("hello_2").is_ok());
+        assert!(validate_plugin_id(".x").is_err());
+        assert!(validate_item_id("word-count.v2_x", "command id").is_ok());
+        assert!(validate_item_id("-x", "command id").is_err());
+        assert!(validate_point_id("iconThemes").is_ok());
+        assert!(validate_point_id("Icon").is_err());
+        assert!(engine_compatible("1.0", false));
+        assert!(engine_compatible(">=1.0, <2", false));
+        assert!(!engine_compatible("^0.2", false), "0.x components don't run on 1.0");
+        assert!(engine_compatible("0.1.3", true));
+        assert!(!engine_compatible("0.10", true));
+    }
+}

crates/ide-extension/src/package.rs

@@ -0,0 +1,465 @@
+//! Plugin distribution: the package file, its
+//! signature, and the static marketplace index.
+//!
+//! - **Package** (`<id>-<version>.oiplugin`): a zip of the manifest, the files
+//!   its declarations reference, the component and licence files, plus
+//!   [`SIGNATURE_FILE`] when signed.
+//! - **Signature**: Ed25519 over `openidea-plugin/1\n<id>\n<version>\n<digest>`,
+//!   `digest` being [`package_digest`] of the unpacked files. A signature
+//!   proves who published the bytes; whether to trust that publisher is the
+//!   index's call.
+//! - **Index** (`index.json`): the publishers and their keys (the trust root),
+//!   the published plugins, and revocations. A publisher owns the id prefix
+//!   `<publisher>.`; a revoked key invalidates everything it signed, a
+//!   revoked plugin version is disabled where it is installed.
+
+use crate::MANIFEST_FILE;
+use base64::Engine as _;
+use ed25519_dalek::{Signature, Signer, SigningKey, VerifyingKey};
+use serde::{Deserialize, Serialize};
+use std::io::{Read, Write};
+use std::path::{Component, Path, PathBuf};
+
+pub const SIGNATURE_FILE: &str = "SIGNATURE.json";
+pub const PACKAGE_EXTENSION: &str = "oiplugin";
+pub const INDEX_FORMAT: u32 = 1;
+/// Limits when unpacking an untrusted package.
+const MAX_ENTRIES: usize = 10_000;
+const MAX_TOTAL: u64 = 512 << 20;
+
+const B64: base64::engine::GeneralPurpose = base64::engine::general_purpose::STANDARD;
+
+/// Content digest of a package: the manifest plus `files` (relative paths).
+pub fn package_digest(dir: &Path, files: &[PathBuf]) -> std::io::Result<String> {
+    let mut all = files.to_vec();
+    all.push(PathBuf::from(MANIFEST_FILE));
+    crate::ledger::package_hash(dir, &all)
+}
+
+fn signed_message(id: &str, version: &str, digest: &str) -> Vec<u8> {
+    format!("openidea-plugin/1\n{id}\n{version}\n{digest}").into_bytes()
+}
+
+/// `SIGNATURE.json` of a signed package.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct PackageSignature {
+    pub publisher: String,
+    /// Ed25519 public key, base64.
+    pub key: String,
+    /// Ed25519 signature, base64.
+    pub signature: String,
+}
+
+/// A publisher's key pair (the 32-byte seed, base64, in a file only the publisher has).
+pub struct PublisherKey(SigningKey);
+
+impl PublisherKey {
+    pub fn from_seed(seed: [u8; 32]) -> Self {
+        Self(SigningKey::from_bytes(&seed))
+    }
+
+    /// The seed as written by `openidea-plugin keygen`.
+    pub fn from_base64(text: &str) -> Result<Self, String> {
+        let bytes = B64.decode(text.trim()).map_err(|e| format!("key file: {e}"))?;
+        let seed: [u8; 32] = bytes.try_into().map_err(|_| "key file: expected a 32-byte key".to_owned())?;
+        Ok(Self::from_seed(seed))
+    }
+
+    pub fn seed_base64(&self) -> String {
+        B64.encode(self.0.to_bytes())
+    }
+
+    pub fn public_base64(&self) -> String {
+        B64.encode(self.0.verifying_key().to_bytes())
+    }
+
+    pub fn sign(&self, publisher: &str, id: &str, version: &str, digest: &str) -> PackageSignature {
+        let sig = self.0.sign(&signed_message(id, version, digest));
+        PackageSignature {
+            publisher: publisher.into(),
+            key: self.public_base64(),
+            signature: B64.encode(sig.to_bytes()),
+        }
+    }
+}
+
+impl PackageSignature {
+    /// Whether the signature is valid for `id`, `version` and `digest` (the
+    /// key's validity is checked against an [`Index`]).
+    pub fn check(&self, id: &str, version: &str, digest: &str) -> Result<(), String> {
+        let key: [u8; 32] = B64
+            .decode(&self.key)
+            .ok()
+            .and_then(|b| b.try_into().ok())
+            .ok_or_else(|| "signature: malformed public key".to_owned())?;
+        let key = VerifyingKey::from_bytes(&key).map_err(|_| "signature: invalid public key".to_owned())?;
+        let sig: [u8; 64] = B64
+            .decode(&self.signature)
+            .ok()
+            .and_then(|b| b.try_into().ok())
+            .ok_or_else(|| "signature: malformed".to_owned())?;
+        key.verify_strict(&signed_message(id, version, digest), &Signature::from_bytes(&sig))
+            .map_err(|_| "the signature does not match the package (it was changed after signing)".to_owned())
+    }
+}
+
+/// Writes the package `out` from `dir`: the manifest, `files`, and the signature if any.
+pub fn pack(dir: &Path, files: &[PathBuf], out: &Path, signature: Option<&PackageSignature>) -> Result<(), String> {
+    let io = |e: std::io::Error| e.to_string();
+    let file = std::fs::File::create(out).map_err(io)?;
+    let mut zip = zip::ZipWriter::new(file);
+    let options = zip::write::SimpleFileOptions::default().compression_method(zip::CompressionMethod::Deflated);
+    let mut names: Vec<PathBuf> = std::iter::once(PathBuf::from(MANIFEST_FILE)).chain(files.iter().cloned()).collect();
+    names.sort();
+    names.dedup();
+    for rel in names {
+        let name = rel.to_str().ok_or("non UTF-8 file name")?.replace('\\', "/");
+        zip.start_file(name, options).map_err(|e| e.to_string())?;
+        let bytes = std::fs::read(dir.join(&rel)).map_err(|e| format!("{}: {e}", rel.display()))?;
+        zip.write_all(&bytes).map_err(io)?;
+    }
+    if let Some(sig) = signature {
+        zip.start_file(SIGNATURE_FILE, options).map_err(|e| e.to_string())?;
+        zip.write_all(serde_json::to_string_pretty(sig).map_err(|e| e.to_string())?.as_bytes()).map_err(io)?;
+    }
+    zip.finish().map_err(|e| e.to_string())?;
+    Ok(())
+}
+
+/// What [`unpack`] wrote.
+#[derive(Debug)]
+pub struct Unpacked {
+    /// Every file but the manifest and the signature, relative.
+    pub files: Vec<PathBuf>,
+    pub signature: Option<PackageSignature>,
+}
+
+/// `name` as a relative path that stays inside the package.
+fn safe_path(name: &str) -> Option<PathBuf> {
+    let p = Path::new(name);
+    (!name.is_empty() && p.components().all(|c| matches!(c, Component::Normal(_)))).then(|| p.to_path_buf())
+}
+
+/// Archiver metadata at the top of an archive, not part of a package
+/// (`__MACOSX/…`, `.DS_Store`, AppleDouble `._…` files).
+fn archiver_metadata(name: &str) -> bool {
+    let top = name.split('/').next().unwrap_or_default();
+    top == "__MACOSX" || top == ".DS_Store" || (top.starts_with("._") && top.len() > 2)
+}
+
+/// Where the package is inside an archive: at its root (`.oiplugin`, or a zip
+/// of the package's contents) or in its only folder (a zip of the package
+/// folder). `None` when neither holds a manifest.
+fn package_prefix(names: &[String]) -> Option<String> {
+    if names.iter().any(|n| n == MANIFEST_FILE) {
+        return Some(String::new());
+    }
+    let mut tops = names.iter().filter(|n| !archiver_metadata(n)).map(|n| n.split('/').next().unwrap_or_default());
+    let top = tops.next()?;
+    if tops.any(|t| t != top) {
+        return None;
+    }
+    let prefix = format!("{top}/");
+    names.iter().any(|n| *n == format!("{prefix}{MANIFEST_FILE}")).then_some(prefix)
+}
+
+/// Extracts the package `archive` (an `.oiplugin`, or a `.zip` of a package
+/// folder or of its contents) into the empty directory `dest`, refusing
+/// paths leaving it, links, and oversized contents.
+pub fn unpack(archive: &Path, dest: &Path) -> Result<Unpacked, String> {
+    let file = std::fs::File::open(archive).map_err(|e| format!("{}: {e}", archive.display()))?;
+    let mut zip =
+        zip::ZipArchive::new(file).map_err(|e| format!("{}: not a plugin package ({e})", archive.display()))?;
+    if zip.len() > MAX_ENTRIES {
+        return Err(format!("more than {MAX_ENTRIES} files"));
+    }
+    let mut names = Vec::with_capacity(zip.len());
+    for i in 0..zip.len() {
+        let entry = zip.by_index(i).map_err(|e| e.to_string())?;
+        if !entry.is_dir() {
+            names.push(entry.name().map_err(|e| e.to_string())?.into_owned());
+        }
+    }
+    // An IntelliJ plugin or any other zip: say what is missing rather than fail later.
+    let prefix = package_prefix(&names).ok_or_else(|| {
+        format!("{} is not an OpenIDEA plugin: no {MANIFEST_FILE} at its root or in its only folder", archive.display())
+    })?;
+    std::fs::create_dir_all(dest).map_err(|e| e.to_string())?;
+    let (mut files, mut signature, mut total, mut manifest) = (Vec::new(), None, 0u64, false);
+    for i in 0..zip.len() {
+        let mut entry = zip.by_index(i).map_err(|e| e.to_string())?;
+        if entry.is_dir() {
+            continue;
+        }
+        let full = entry.name().map_err(|e| e.to_string())?.into_owned();
+        // Outside the package folder there is only archiver metadata (`package_prefix` checked).
+        let Some(name) = full.strip_prefix(&prefix).map(str::to_owned) else { continue };
+        if archiver_metadata(&name) {
+            continue;
+        }
+        if entry.is_symlink() {
+            return Err(format!("{full}: links are not allowed in packages"));
+        }
+        let rel = safe_path(&name).ok_or_else(|| format!("invalid path {full:?} in package"))?;
+        let mut bytes = Vec::new();
+        entry.by_ref().take(MAX_TOTAL - total + 1).read_to_end(&mut bytes).map_err(|e| e.to_string())?;
+        total += bytes.len() as u64;
+        if total > MAX_TOTAL {
+            return Err(format!("the package unpacks to more than {} MiB", MAX_TOTAL >> 20));
+        }
+        if rel == Path::new(SIGNATURE_FILE) {
+            signature = Some(serde_json::from_slice(&bytes).map_err(|e| format!("{SIGNATURE_FILE}: {e}"))?);
+            continue;
+        }
+        let to = dest.join(&rel);
+        if let Some(parent) = to.parent() {
+            std::fs::create_dir_all(parent).map_err(|e| e.to_string())?;
+        }
+        std::fs::write(&to, bytes).map_err(|e| e.to_string())?;
+        if rel == Path::new(MANIFEST_FILE) {
+            manifest = true;
+        } else {
+            files.push(rel);
+        }
+    }
+    if !manifest {
+        return Err(format!("the package has no {MANIFEST_FILE}"));
+    }
+    files.sort();
+    Ok(Unpacked { files, signature })
+}
+
+// ---- index -------------------------------------------------------------------
+
+#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct Index {
+    pub format: u32,
+    #[serde(default)]
+    pub publishers: Vec<Publisher>,
+    #[serde(default)]
+    pub plugins: Vec<IndexEntry>,
+    #[serde(default)]
+    pub revoked: Vec<Revocation>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct Publisher {
+    /// Owns plugin ids `<id>.…`.
+    pub id: String,
+    pub name: String,
+    pub keys: Vec<KeyEntry>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct KeyEntry {
+    /// Ed25519 public key, base64.
+    pub key: String,
+    /// Packages signed with it are no longer trusted.
+    #[serde(default)]
+    pub revoked: bool,
+}
+
+/// A published plugin version.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct IndexEntry {
+    pub id: String,
+    pub name: String,
+    pub version: String,
+    #[serde(default)]
+    pub description: String,
+    #[serde(default)]
+    pub authors: Vec<String>,
+    pub publisher: String,
+    /// The package, relative to the index (or an absolute URL).
+    pub download: String,
+    /// [`package_digest`] of its contents.
+    pub digest: String,
+    #[serde(default)]
+    pub capabilities: Vec<String>,
+}
+
+/// A plugin (all versions when `versions` is empty) that must not run.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct Revocation {
+    pub id: String,
+    #[serde(default)]
+    pub versions: Vec<String>,
+    pub reason: String,
+}
+
+impl Index {
+    pub fn parse(text: &str) -> Result<Self, String> {
+        let index: Index = serde_json::from_str(text).map_err(|e| format!("index: {e}"))?;
+        if index.format != INDEX_FORMAT {
+            return Err(format!("index format {} is not supported (this IDE reads {INDEX_FORMAT})", index.format));
+        }
+        Ok(index)
+    }
+
+    /// The revocation that applies to `id` at `version`.
+    pub fn revocation(&self, id: &str, version: &str) -> Option<&Revocation> {
+        self.revoked.iter().find(|r| r.id == id && (r.versions.is_empty() || r.versions.iter().any(|v| v == version)))
+    }
+
+    /// Whether `key` (base64) belongs to a publisher and was revoked.
+    pub fn key_revoked(&self, key: &str) -> bool {
+        self.publishers.iter().flat_map(|p| &p.keys).any(|k| k.key == key && k.revoked)
+    }
+
+    /// The trusted publisher of a signed package: the signature is valid, its
+    /// key is one of the publisher's and not revoked, and the publisher owns
+    /// the plugin's id prefix.
+    pub fn verify(&self, sig: &PackageSignature, id: &str, version: &str, digest: &str) -> Result<String, String> {
+        let publisher = self
+            .publishers
+            .iter()
+            .find(|p| p.id == sig.publisher)
+            .ok_or_else(|| format!("unknown publisher {:?}", sig.publisher))?;
+        let key = publisher
+            .keys
+            .iter()
+            .find(|k| k.key == sig.key)
+            .ok_or_else(|| format!("the key is not one of {}'s", publisher.name))?;
+        if key.revoked {
+            return Err(format!("{}'s signing key was revoked", publisher.name));
+        }
+        if !id.starts_with(&format!("{}.", publisher.id)) {
+            return Err(format!("{} may only publish plugins named {}.*", publisher.name, publisher.id));
+        }
+        sig.check(id, version, digest)?;
+        Ok(publisher.id.clone())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn package(dir: &Path) -> Vec<PathBuf> {
+        std::fs::create_dir_all(dir.join("dist")).unwrap();
+        std::fs::write(dir.join(MANIFEST_FILE), "id = \"acme.tools\"\nversion = \"1.0.0\"").unwrap();
+        std::fs::write(dir.join("dist/plugin.wasm"), b"\0asm").unwrap();
+        vec![PathBuf::from("dist/plugin.wasm")]
+    }
+
+    fn index(key: &PublisherKey) -> Index {
+        Index {
+            format: INDEX_FORMAT,
+            publishers: vec![Publisher {
+                id: "acme".into(),
+                name: "ACME".into(),
+                keys: vec![KeyEntry { key: key.public_base64(), revoked: false }],
+            }],
+            plugins: Vec::new(),
+            revoked: vec![Revocation {
+                id: "acme.bad".into(),
+                versions: vec!["1.0.0".into()],
+                reason: "malware".into(),
+            }],
+        }
+    }
+
+    #[test]
+    fn signed_packages_round_trip_and_tampering_is_caught() {
+        let tmp = tempfile::tempdir().unwrap();
+        let src = tmp.path().join("src");
+        let files = package(&src);
+        let digest = package_digest(&src, &files).unwrap();
+        let key = PublisherKey::from_seed([7; 32]);
+        let sig = key.sign("acme", "acme.tools", "1.0.0", &digest);
+        let out = tmp.path().join("acme.tools-1.0.0.oiplugin");
+        pack(&src, &files, &out, Some(&sig)).unwrap();
+
+        let dest = tmp.path().join("dest");
+        let unpacked = unpack(&out, &dest).unwrap();
+        assert_eq!(unpacked.files, files);
+        assert_eq!(package_digest(&dest, &unpacked.files).unwrap(), digest);
+        let index = index(&key);
+        assert_eq!(index.verify(unpacked.signature.as_ref().unwrap(), "acme.tools", "1.0.0", &digest).unwrap(), "acme");
+
+        // Changed bytes, another id, someone else's prefix, a revoked key.
+        assert!(index.verify(&sig, "acme.tools", "1.0.0", "0000").is_err());
+        assert!(index.verify(&sig, "acme.tools", "1.0.1", &digest).is_err());
+        let other = PublisherKey::from_seed([9; 32]).sign("acme", "acme.tools", "1.0.0", &digest);
+        assert!(index.verify(&other, "acme.tools", "1.0.0", &digest).unwrap_err().contains("not one of"));
+        let foreign = key.sign("acme", "evil.tools", "1.0.0", &digest);
+        assert!(index.verify(&foreign, "evil.tools", "1.0.0", &digest).unwrap_err().contains("acme.*"));
+        let mut revoked = index.clone();
+        revoked.publishers[0].keys[0].revoked = true;
+        assert!(revoked.verify(&sig, "acme.tools", "1.0.0", &digest).unwrap_err().contains("revoked"));
+        assert!(revoked.key_revoked(&sig.key));
+        assert_eq!(index.revocation("acme.bad", "1.0.0").unwrap().reason, "malware");
+        assert!(index.revocation("acme.bad", "1.0.1").is_none());
+        assert_eq!(PublisherKey::from_base64(&key.seed_base64()).unwrap().public_base64(), key.public_base64());
+    }
+
+    #[test]
+    fn unpacking_refuses_paths_leaving_the_package() {
+        let tmp = tempfile::tempdir().unwrap();
+        let out = tmp.path().join("evil.oiplugin");
+        let mut zip = zip::ZipWriter::new(std::fs::File::create(&out).unwrap());
+        let o = zip::write::SimpleFileOptions::default();
+        zip.start_file(MANIFEST_FILE, o).unwrap();
+        zip.write_all(b"id = \"x\"").unwrap();
+        zip.start_file("../outside.txt", o).unwrap();
+        zip.write_all(b"x").unwrap();
+        zip.finish().unwrap();
+        let err = unpack(&out, &tmp.path().join("dest")).unwrap_err();
+        assert!(err.contains("invalid path"), "{err}");
+        assert!(!tmp.path().join("outside.txt").exists());
+        assert!(Index::parse(r#"{"format": 2}"#).is_err());
+    }
+
+    fn zip_of(path: &Path, entries: &[(&str, &str)]) {
+        let mut zip = zip::ZipWriter::new(std::fs::File::create(path).unwrap());
+        for (name, body) in entries {
+            zip.start_file(*name, zip::write::SimpleFileOptions::default()).unwrap();
+            zip.write_all(body.as_bytes()).unwrap();
+        }
+        zip.finish().unwrap();
+    }
+
+    #[test]
+    fn a_zip_holds_the_package_at_its_root_or_in_its_only_folder() {
+        let tmp = tempfile::tempdir().unwrap();
+        let manifest = "id = \"acme.tools\"";
+        let at_root = tmp.path().join("root.zip");
+        zip_of(&at_root, &[(MANIFEST_FILE, manifest), ("dist/plugin.wasm", "w"), (".DS_Store", "x")]);
+        let got = unpack(&at_root, &tmp.path().join("a")).unwrap();
+        assert_eq!(got.files, [PathBuf::from("dist/plugin.wasm")]);
+
+        // What zipping the folder in Finder makes: the folder plus `__MACOSX`.
+        let folder = tmp.path().join("folder.zip");
+        zip_of(
+            &folder,
+            &[
+                ("acme-tools/plugin.toml", manifest),
+                ("acme-tools/dist/plugin.wasm", "w"),
+                ("__MACOSX/acme-tools/._plugin.toml", "x"),
+            ],
+        );
+        let dest = tmp.path().join("b");
+        let got = unpack(&folder, &dest).unwrap();
+        assert_eq!(got.files, [PathBuf::from("dist/plugin.wasm")]);
+        assert!(dest.join(MANIFEST_FILE).is_file());
+        assert!(!dest.join("__MACOSX").exists() && !dest.join("acme-tools").exists());
+
+        // Two folders, a manifest one level too deep, or none (an IntelliJ plugin): not a package.
+        for (name, entries) in [
+            ("two.zip", &[("a/plugin.toml", manifest), ("b/x.txt", "x")][..]),
+            ("deep.zip", &[("a/b/plugin.toml", manifest)][..]),
+            ("intellij.zip", &[("my-plugin/lib/my-plugin.jar", "jar")][..]),
+        ] {
+            let path = tmp.path().join(name);
+            zip_of(&path, entries);
+            let err = unpack(&path, &tmp.path().join(name).with_extension("out")).unwrap_err();
+            assert!(err.contains("is not an OpenIDEA plugin"), "{name}: {err}");
+        }
+    }
+}

crates/ide-extension/src/point.rs

@@ -0,0 +1,175 @@
+//! The extension point contract (plan 4.1).
+
+use crate::capability::Capability;
+use crate::manifest::{Manifest, check_relative};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+/// Where a contribution takes effect (plan 3, placement rules).
+#[derive(Clone, Copy, Debug, PartialEq, Eq, serde::Serialize, serde::Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub enum Placement {
+    /// Projected to the client (menus, keybindings, themes, icons).
+    Ui,
+    /// Takes effect on the machine the project is on (languages, LSP, run configurations).
+    Workspace,
+}
+
+/// The package a declaration comes from, as extension points see it.
+#[derive(Clone, Debug)]
+pub struct Package {
+    pub manifest: Arc<Manifest>,
+    /// Package directory.
+    pub dir: PathBuf,
+    /// Hash of the package's files when they never change (an installed
+    /// copy): validated declarations are then reused from the
+    /// [`ContributionIndex`](crate::ContributionIndex).
+    pub digest: Option<Arc<str>>,
+}
+
+/// Largest single package file an extension point reads.
+pub const MAX_PACKAGE_FILE: u64 = 8 << 20;
+
+impl Package {
+    pub fn new(manifest: Manifest, dir: PathBuf) -> Self {
+        Self { manifest: Arc::new(manifest), dir, digest: None }
+    }
+
+    pub fn with_digest(mut self, digest: &str) -> Self {
+        self.digest = Some(digest.into());
+        self
+    }
+
+    pub fn id(&self) -> &str {
+        &self.manifest.id
+    }
+
+    /// Resolves a package-relative path, refusing anything that leaves the
+    /// package (`..`, absolute paths, symlinks pointing outside).
+    pub fn resolve(&self, rel: &Path) -> Result<PathBuf, String> {
+        check_relative(rel, "path")?;
+        let joined = self.dir.join(rel);
+        let real = joined.canonicalize().map_err(|_| format!("{}: no such file in the plugin", rel.display()))?;
+        let root = self.dir.canonicalize().map_err(|e| format!("plugin directory: {e}"))?;
+        if !real.starts_with(&root) {
+            return Err(format!("{}: points outside the plugin", rel.display()));
+        }
+        Ok(real)
+    }
+
+    pub fn read_bytes(&self, rel: &Path) -> Result<Vec<u8>, String> {
+        let real = self.resolve(rel)?;
+        let meta = std::fs::metadata(&real).map_err(|e| format!("{}: {e}", rel.display()))?;
+        if !meta.is_file() {
+            return Err(format!("{}: not a file", rel.display()));
+        }
+        if meta.len() > MAX_PACKAGE_FILE {
+            return Err(format!("{}: larger than {} MiB", rel.display(), MAX_PACKAGE_FILE >> 20));
+        }
+        std::fs::read(&real).map_err(|e| format!("{}: {e}", rel.display()))
+    }
+
+    pub fn read_text(&self, rel: &Path) -> Result<String, String> {
+        String::from_utf8(self.read_bytes(rel)?).map_err(|_| format!("{}: not UTF-8 text", rel.display()))
+    }
+}
+
+/// Undoes one committed contribution. Dropping without [`dispose`](Self::dispose) also disposes.
+#[must_use = "dropping a Disposable undoes the contribution"]
+pub struct Disposable(Option<Box<dyn FnOnce() + Send>>);
+
+impl Disposable {
+    pub fn new(f: impl FnOnce() + Send + 'static) -> Self {
+        Self(Some(Box::new(f)))
+    }
+
+    /// A contribution with nothing to undo.
+    pub fn noop() -> Self {
+        Self(None)
+    }
+
+    pub fn dispose(mut self) {
+        if let Some(f) = self.0.take() {
+            f();
+        }
+    }
+}
+
+impl Drop for Disposable {
+    fn drop(&mut self) {
+        if let Some(f) = self.0.take() {
+            f();
+        }
+    }
+}
+
+impl std::fmt::Debug for Disposable {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("Disposable")
+    }
+}
+
+pub type Commit = Box<dyn FnOnce() -> Result<Disposable, String> + Send>;
+
+/// A validated declaration, ready to take effect.
+pub struct Prepared {
+    /// Capabilities this declaration needs (a language with an LSP → `process:<binary>`).
+    pub capabilities: Vec<Capability>,
+    /// Package files the declaration references (copied on install).
+    pub files: Vec<PathBuf>,
+    /// Identity within the point: a later declaration with the same key replaces
+    /// the earlier one of the same plugin (re-registering a command).
+    pub key: Option<String>,
+    /// User-facing one-liner for the plugin details page ("Insert Date").
+    pub label: String,
+    /// Makes it take effect. Must not fail for reasons `prepare` could have checked.
+    pub commit: Commit,
+}
+
+impl Prepared {
+    pub fn new(label: impl Into<String>, commit: impl FnOnce() -> Result<Disposable, String> + Send + 'static) -> Self {
+        Self { capabilities: Vec::new(), files: Vec::new(), key: None, label: label.into(), commit: Box::new(commit) }
+    }
+
+    pub fn key(mut self, key: impl Into<String>) -> Self {
+        self.key = Some(key.into());
+        self
+    }
+
+    pub fn file(mut self, path: impl Into<PathBuf>) -> Self {
+        self.files.push(path.into());
+        self
+    }
+
+    pub fn capability(mut self, cap: Capability) -> Self {
+        if !self.capabilities.contains(&cap) {
+            self.capabilities.push(cap);
+        }
+        self
+    }
+}
+
+impl std::fmt::Debug for Prepared {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Prepared").field("key", &self.key).field("label", &self.label).finish_non_exhaustive()
+    }
+}
+
+/// A kind of contribution (`contributes.<id>` in the manifest). Implemented by
+/// the crate that owns the feature; registered once in an [`crate::ExtensionRegistry`].
+pub trait ExtensionPoint: Send + Sync {
+    /// `"languages"`, `"iconThemes"`, …
+    fn id(&self) -> &'static str;
+
+    fn placement(&self) -> Placement;
+
+    /// Parses and validates one declaration without side effects, and works
+    /// out the capabilities it needs. `Ui` points validate completely here: the
+    /// client's projection is not allowed to fail.
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String>;
+}
+
+/// Deserializes a declaration with serde, prefixing errors with the point id.
+pub fn decode<T: serde::de::DeserializeOwned>(point: &str, decl: toml::Value) -> Result<T, String> {
+    decl.try_into().map_err(|e: toml::de::Error| format!("contributes.{point}: {}", e.message()))
+}

crates/ide-extension/src/registry.rs

@@ -0,0 +1,305 @@
+//! Extension points plus the contributions committed to them, accounted per plugin.
+
+use crate::capability::Capability;
+use crate::point::{Disposable, ExtensionPoint, Package, Placement, Prepared};
+use parking_lot::{Mutex, RwLock};
+use serde::{Deserialize, Serialize};
+use specta::Type;
+use std::collections::BTreeMap;
+use std::path::PathBuf;
+use std::sync::Arc;
+
+/// A contribution as the plugin details page lists it.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ContributionInfo {
+    pub point: String,
+    pub label: String,
+}
+
+struct Entry {
+    point: &'static str,
+    key: Option<String>,
+    label: String,
+    disposable: Disposable,
+}
+
+/// Every declaration of a package, validated; nothing has taken effect yet.
+pub struct PreparedSet {
+    pub plugin: String,
+    /// Union of what the declarations need (beyond the manifest's own list).
+    pub capabilities: Vec<Capability>,
+    /// Package files the declarations reference.
+    pub files: Vec<PathBuf>,
+    /// Declarations for extension points this host does not know (skipped).
+    pub warnings: Vec<String>,
+    items: Vec<(&'static str, Prepared)>,
+}
+
+impl PreparedSet {
+    pub fn is_empty(&self) -> bool {
+        self.items.is_empty()
+    }
+
+    pub fn len(&self) -> usize {
+        self.items.len()
+    }
+}
+
+impl std::fmt::Debug for PreparedSet {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("PreparedSet")
+            .field("plugin", &self.plugin)
+            .field("items", &self.items.len())
+            .field("warnings", &self.warnings)
+            .finish()
+    }
+}
+
+#[derive(Default)]
+pub struct ExtensionRegistry {
+    points: RwLock<BTreeMap<&'static str, Arc<dyn ExtensionPoint>>>,
+    /// plugin id → its contributions in commit order.
+    entries: Mutex<BTreeMap<String, Vec<Entry>>>,
+}
+
+impl ExtensionRegistry {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Adds an extension point. Ids are unique.
+    pub fn register(&self, point: Arc<dyn ExtensionPoint>) -> Result<(), String> {
+        let id = point.id();
+        crate::manifest::validate_point_id(id)?;
+        let mut points = self.points.write();
+        if points.contains_key(id) {
+            return Err(format!("extension point {id:?} is already registered"));
+        }
+        points.insert(id, point);
+        Ok(())
+    }
+
+    pub fn point_ids(&self) -> Vec<&'static str> {
+        self.points.read().keys().copied().collect()
+    }
+
+    pub fn placement(&self, point: &str) -> Option<Placement> {
+        self.points.read().get(point).map(|p| p.placement())
+    }
+
+    fn point(&self, id: &str) -> Option<Arc<dyn ExtensionPoint>> {
+        self.points.read().get(id).cloned()
+    }
+
+    /// Validates every `contributes.<point>` declaration of `pkg`. Fails as a
+    /// whole on the first invalid declaration; unknown points are skipped with
+    /// a warning (forward compatibility).
+    pub fn prepare(&self, pkg: &Package) -> Result<PreparedSet, String> {
+        let mut set = PreparedSet {
+            plugin: pkg.id().to_owned(),
+            capabilities: Vec::new(),
+            files: Vec::new(),
+            warnings: Vec::new(),
+            items: Vec::new(),
+        };
+        for point_id in pkg.manifest.contributes.keys() {
+            let Some(point) = self.point(point_id) else {
+                let msg = format!("contributes.{point_id}: not supported by this version of the IDE; skipped");
+                tracing::warn!(plugin = %pkg.id(), "{msg}");
+                set.warnings.push(msg);
+                continue;
+            };
+            for (i, decl) in pkg.manifest.declarations(point_id).into_iter().enumerate() {
+                let prepared = point
+                    .prepare(pkg, decl)
+                    .map_err(|e| format!("contributes.{point_id}[{i}]: {}", strip_prefix(&e, point_id)))?;
+                for cap in &prepared.capabilities {
+                    if !set.capabilities.contains(cap) {
+                        set.capabilities.push(cap.clone());
+                    }
+                }
+                for f in &prepared.files {
+                    if !set.files.contains(f) {
+                        set.files.push(f.clone());
+                    }
+                }
+                set.items.push((point.id(), prepared));
+            }
+        }
+        Ok(set)
+    }
+
+    /// Makes a prepared set take effect, all or nothing: if one commit fails,
+    /// the ones before it are disposed in reverse order.
+    pub fn commit(&self, set: PreparedSet) -> Result<(), String> {
+        let mut committed: Vec<Entry> = Vec::with_capacity(set.items.len());
+        for (point, prepared) in set.items {
+            let Prepared { key, label, commit, .. } = prepared;
+            match commit() {
+                Ok(disposable) => committed.push(Entry { point, key, label, disposable }),
+                Err(e) => {
+                    tracing::error!(plugin = %set.plugin, "contributes.{point}: commit failed: {e}");
+                    while let Some(entry) = committed.pop() {
+                        entry.disposable.dispose();
+                    }
+                    return Err(format!("contributes.{point}: {e}"));
+                }
+            }
+        }
+        let replaced = {
+            let mut entries = self.entries.lock();
+            let list = entries.entry(set.plugin).or_default();
+            let mut replaced = Vec::new();
+            for new in &committed {
+                if let Some(key) = &new.key
+                    && let Some(pos) = list.iter().position(|e| e.point == new.point && e.key.as_ref() == Some(key))
+                {
+                    replaced.push(list.remove(pos));
+                }
+            }
+            list.extend(committed);
+            replaced
+        };
+        for old in replaced.into_iter().rev() {
+            old.disposable.dispose();
+        }
+        Ok(())
+    }
+
+    /// Withdraws everything `plugin` contributed, newest first.
+    pub fn dispose_plugin(&self, plugin: &str) -> bool {
+        let list = self.entries.lock().remove(plugin).unwrap_or_default();
+        let any = !list.is_empty();
+        for entry in list.into_iter().rev() {
+            entry.disposable.dispose();
+        }
+        any
+    }
+
+    pub fn contributions(&self, plugin: &str) -> Vec<ContributionInfo> {
+        self.entries
+            .lock()
+            .get(plugin)
+            .map(|list| {
+                list.iter().map(|e| ContributionInfo { point: e.point.into(), label: e.label.clone() }).collect()
+            })
+            .unwrap_or_default()
+    }
+
+    /// How many contributions `plugin` has at `point`.
+    pub fn count(&self, plugin: &str, point: &str) -> usize {
+        self.entries.lock().get(plugin).map_or(0, |list| list.iter().filter(|e| e.point == point).count())
+    }
+
+    /// Plugins with at least one contribution.
+    pub fn plugins(&self) -> Vec<String> {
+        self.entries.lock().iter().filter(|(_, l)| !l.is_empty()).map(|(id, _)| id.clone()).collect()
+    }
+}
+
+fn strip_prefix<'a>(e: &'a str, point: &str) -> &'a str {
+    e.strip_prefix(&format!("contributes.{point}: ")).unwrap_or(e)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::manifest::Manifest;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    /// Records live items in a shared list; `fail = true` makes commit fail.
+    struct Recording {
+        id: &'static str,
+        live: Arc<Mutex<Vec<String>>>,
+        commits: Arc<AtomicUsize>,
+    }
+
+    impl ExtensionPoint for Recording {
+        fn id(&self) -> &'static str {
+            self.id
+        }
+        fn placement(&self) -> Placement {
+            Placement::Ui
+        }
+        fn prepare(&self, _pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+            let name = decl.get("name").and_then(|v| v.as_str()).ok_or("missing name")?.to_owned();
+            let fail = decl.get("fail").and_then(|v| v.as_bool()).unwrap_or(false);
+            let (live, commits) = (self.live.clone(), self.commits.clone());
+            let label = name.clone();
+            let mut p = Prepared::new(label, move || {
+                commits.fetch_add(1, Ordering::SeqCst);
+                if fail {
+                    return Err("boom".into());
+                }
+                live.lock().push(name.clone());
+                Ok(Disposable::new(move || live.lock().retain(|n| *n != name)))
+            });
+            if let Some(f) = decl.get("file").and_then(|v| v.as_str()) {
+                p = p.file(f);
+            }
+            if decl.get("key").and_then(|v| v.as_bool()).unwrap_or(false) {
+                p = p.key("k");
+            }
+            Ok(p)
+        }
+    }
+
+    fn setup() -> (ExtensionRegistry, Arc<Mutex<Vec<String>>>) {
+        let reg = ExtensionRegistry::new();
+        let live = Arc::new(Mutex::new(Vec::new()));
+        let commits = Arc::new(AtomicUsize::new(0));
+        reg.register(Arc::new(Recording { id: "things", live: live.clone(), commits: commits.clone() })).unwrap();
+        reg.register(Arc::new(Recording { id: "others", live: live.clone(), commits })).unwrap();
+        (reg, live)
+    }
+
+    fn pkg(contributes: &str) -> Package {
+        let src = format!("id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n{contributes}");
+        Package::new(Manifest::parse(&src).unwrap(), PathBuf::from("/nonexistent"))
+    }
+
+    #[test]
+    fn commits_and_disposes_per_plugin() {
+        let (reg, live) = setup();
+        assert!(
+            reg.register(Arc::new(Recording { id: "things", live: live.clone(), commits: Default::default() }))
+                .is_err()
+        );
+        let p = pkg(
+            "[[contributes.things]]\nname = \"a\"\nfile = \"x.json\"\n[[contributes.things]]\nname = \"b\"\n[contributes.others]\nname = \"c\"",
+        );
+        let set = reg.prepare(&p).unwrap();
+        assert_eq!(set.len(), 3);
+        assert_eq!(set.files, [PathBuf::from("x.json")]);
+        assert!(live.lock().is_empty(), "prepare has no side effects");
+        reg.commit(set).unwrap();
+        assert_eq!(*live.lock(), ["c", "a", "b"]);
+        assert_eq!(reg.count("p", "things"), 2);
+        assert_eq!(reg.contributions("p").len(), 3);
+        assert!(reg.dispose_plugin("p"));
+        assert!(live.lock().is_empty());
+    }
+
+    #[test]
+    fn a_failed_commit_rolls_back() {
+        let (reg, live) = setup();
+        let p = pkg("[[contributes.things]]\nname = \"a\"\n[[contributes.things]]\nname = \"b\"\nfail = true");
+        let err = reg.commit(reg.prepare(&p).unwrap()).unwrap_err();
+        assert!(err.contains("boom"));
+        assert!(live.lock().is_empty(), "a was undone");
+        assert!(reg.contributions("p").is_empty());
+    }
+
+    #[test]
+    fn invalid_declarations_fail_prepare_and_unknown_points_warn() {
+        let (reg, _) = setup();
+        let err = reg.prepare(&pkg("[[contributes.things]]\nnope = 1")).unwrap_err();
+        assert_eq!(err, "contributes.things[0]: missing name");
+        let set =
+            reg.prepare(&pkg("[[contributes.futureThing]]\nx = 1\n[[contributes.things]]\nname = \"a\"")).unwrap();
+        assert_eq!(set.len(), 1);
+        assert_eq!(set.warnings.len(), 1);
+        assert!(set.warnings[0].contains("futureThing"));
+    }
+}

crates/ide-extension/src/ui.rs

@@ -0,0 +1,247 @@
+//! UI contributions: validated declarations projected to the client.
+//!
+//! A `Ui` extension point validates a declaration completely in Rust and
+//! commits it as JSON into the [`UiStore`]; the client receives the store's
+//! snapshot and projects each item onto an existing `register*` function
+//! (`defineUiPoint` in `src/features/plugins/projection.ts`). Large payloads
+//! (icon SVGs) go into the store's assets and are fetched on demand.
+
+use crate::index::ContributionIndex;
+use crate::point::{Disposable, ExtensionPoint, Package, Placement, Prepared};
+use parking_lot::RwLock;
+use serde::{Deserialize, Serialize};
+use specta::Type;
+use std::collections::BTreeMap;
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+/// One projected declaration.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct UiContribution {
+    pub plugin_id: String,
+    /// Extension point id (`commands`, `iconThemes`, …).
+    pub point: String,
+    /// Stable within (plugin, point): the client keys its registrations on it.
+    pub key: String,
+    /// The validated declaration, shaped by the point.
+    #[specta(type = specta_typescript::Unknown)]
+    pub decl: serde_json::Value,
+}
+
+struct Item {
+    seq: u64,
+    contribution: UiContribution,
+}
+
+/// Committed UI contributions of all plugins.
+#[derive(Default)]
+pub struct UiStore {
+    items: RwLock<Vec<Item>>,
+    /// (plugin, asset id) → content.
+    assets: RwLock<BTreeMap<(String, String), Arc<str>>>,
+    seq: AtomicU64,
+    revision: AtomicU64,
+    index: RwLock<Option<Arc<ContributionIndex>>>,
+}
+
+impl UiStore {
+    pub fn new() -> Arc<Self> {
+        Arc::new(Self::default())
+    }
+
+    /// Adds an item; the returned disposable removes it.
+    pub fn insert(self: &Arc<Self>, contribution: UiContribution) -> Disposable {
+        let seq = self.seq.fetch_add(1, Ordering::Relaxed);
+        self.items.write().push(Item { seq, contribution });
+        self.revision.fetch_add(1, Ordering::Release);
+        let store = Arc::downgrade(self);
+        Disposable::new(move || {
+            if let Some(store) = store.upgrade() {
+                store.items.write().retain(|i| i.seq != seq);
+                store.revision.fetch_add(1, Ordering::Release);
+            }
+        })
+    }
+
+    /// Stores assets of a plugin (ids are unique per plugin; later ones replace).
+    pub fn insert_assets(self: &Arc<Self>, plugin: &str, assets: Vec<(String, String)>) -> Disposable {
+        let keys: Vec<(String, String)> = assets.iter().map(|(id, _)| (plugin.to_owned(), id.clone())).collect();
+        {
+            let mut map = self.assets.write();
+            for (id, content) in assets {
+                map.insert((plugin.to_owned(), id), Arc::from(content));
+            }
+        }
+        let store = Arc::downgrade(self);
+        Disposable::new(move || {
+            if let Some(store) = store.upgrade() {
+                let mut map = store.assets.write();
+                for k in keys {
+                    map.remove(&k);
+                }
+            }
+        })
+    }
+
+    pub fn asset(&self, plugin: &str, id: &str) -> Option<Arc<str>> {
+        self.assets.read().get(&(plugin.to_owned(), id.to_owned())).cloned()
+    }
+
+    /// Assets of `plugin` whose id starts with `prefix`.
+    pub fn assets_with_prefix(&self, plugin: &str, prefix: &str) -> Vec<(String, Arc<str>)> {
+        self.assets
+            .read()
+            .range((plugin.to_owned(), prefix.to_owned())..)
+            .take_while(|((p, id), _)| p == plugin && id.starts_with(prefix))
+            .map(|((_, id), v)| (id.clone(), v.clone()))
+            .collect()
+    }
+
+    /// Where [`UiPoint`]s keep validated declarations of installed packages.
+    pub fn set_index(&self, index: Option<Arc<ContributionIndex>>) {
+        *self.index.write() = index;
+    }
+
+    /// Bumped on every change: clients compare it to skip re-projection.
+    pub fn revision(&self) -> u64 {
+        self.revision.load(Ordering::Acquire)
+    }
+
+    pub fn snapshot(&self) -> Vec<UiContribution> {
+        self.items.read().iter().map(|i| i.contribution.clone()).collect()
+    }
+
+    /// Items of one point, optionally of one plugin.
+    pub fn items(&self, point: &str, plugin: Option<&str>) -> Vec<UiContribution> {
+        self.items
+            .read()
+            .iter()
+            .filter(|i| i.contribution.point == point && plugin.is_none_or(|p| i.contribution.plugin_id == p))
+            .map(|i| i.contribution.clone())
+            .collect()
+    }
+}
+
+/// What a [`UiPoint`]'s validator produces for one declaration.
+#[derive(Debug, Serialize, Deserialize)]
+pub struct UiDecl {
+    pub key: String,
+    pub label: String,
+    pub json: serde_json::Value,
+    /// Package files referenced (copied on install).
+    pub files: Vec<PathBuf>,
+    /// Large validated payloads fetched separately by the client.
+    pub assets: Vec<(String, String)>,
+}
+
+impl UiDecl {
+    pub fn new(key: impl Into<String>, label: impl Into<String>, json: serde_json::Value) -> Self {
+        Self { key: key.into(), label: label.into(), json, files: Vec::new(), assets: Vec::new() }
+    }
+}
+
+type Validate = dyn Fn(&Package, toml::Value) -> Result<UiDecl, String> + Send + Sync;
+
+/// A `Ui` extension point defined by a validator: committing stores the
+/// validated JSON (and assets) in the [`UiStore`]. Most UI contribution types
+/// (menus, keybindings, status bar items, icon themes) are one of these.
+pub struct UiPoint {
+    id: &'static str,
+    store: Arc<UiStore>,
+    validate: Box<Validate>,
+}
+
+impl UiPoint {
+    pub fn new(
+        id: &'static str,
+        store: Arc<UiStore>,
+        validate: impl Fn(&Package, toml::Value) -> Result<UiDecl, String> + Send + Sync + 'static,
+    ) -> Self {
+        Self { id, store, validate: Box::new(validate) }
+    }
+}
+
+impl ExtensionPoint for UiPoint {
+    fn id(&self) -> &'static str {
+        self.id
+    }
+
+    fn placement(&self) -> Placement {
+        Placement::Ui
+    }
+
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+        let index = pkg.digest.as_ref().and_then(|_| self.store.index.read().clone());
+        let ui = match index.as_ref().and_then(|i| i.get(pkg, self.id, &decl)) {
+            Some(ui) => ui,
+            None => match &index {
+                Some(i) => {
+                    let ui = (self.validate)(pkg, decl.clone())?;
+                    i.put(pkg, self.id, &decl, &ui);
+                    ui
+                }
+                None => (self.validate)(pkg, decl)?,
+            },
+        };
+        let UiDecl { key, label, json, files, assets } = ui;
+        let store = self.store.clone();
+        let contribution =
+            UiContribution { plugin_id: pkg.id().to_owned(), point: self.id.to_owned(), key: key.clone(), decl: json };
+        let plugin = pkg.id().to_owned();
+        let mut prepared = Prepared::new(label, move || {
+            let item = store.insert(contribution);
+            if assets.is_empty() {
+                return Ok(item);
+            }
+            let assets = store.insert_assets(&plugin, assets);
+            Ok(Disposable::new(move || {
+                item.dispose();
+                assets.dispose();
+            }))
+        })
+        .key(key);
+        prepared.files = files;
+        Ok(prepared)
+    }
+}
+
+/// TOML declaration → JSON for the client.
+pub fn to_json(v: &toml::Value) -> serde_json::Value {
+    serde_json::to_value(v).unwrap_or(serde_json::Value::Null)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::manifest::Manifest;
+    use crate::registry::ExtensionRegistry;
+
+    #[test]
+    fn ui_point_projects_into_the_store() {
+        let store = UiStore::new();
+        let reg = ExtensionRegistry::new();
+        reg.register(Arc::new(UiPoint::new("badges", store.clone(), |_pkg, decl| {
+            let text = decl.get("text").and_then(|v| v.as_str()).ok_or("missing text")?.to_owned();
+            let mut d = UiDecl::new(text.clone(), text.clone(), serde_json::json!({ "text": text }));
+            d.assets.push((format!("badge/{text}"), "<svg/>".into()));
+            Ok(d)
+        })))
+        .unwrap();
+        let src = "id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n\
+                   [[contributes.badges]]\ntext = \"hi\"";
+        let pkg = Package::new(Manifest::parse(src).unwrap(), PathBuf::from("/x"));
+        let rev = store.revision();
+        reg.commit(reg.prepare(&pkg).unwrap()).unwrap();
+        assert!(store.revision() > rev);
+        let items = store.items("badges", Some("p"));
+        assert_eq!(items.len(), 1);
+        assert_eq!(items[0].decl["text"], "hi");
+        assert_eq!(store.asset("p", "badge/hi").as_deref(), Some("<svg/>"));
+        assert_eq!(store.assets_with_prefix("p", "badge/").len(), 1);
+        reg.dispose_plugin("p");
+        assert!(store.snapshot().is_empty());
+        assert!(store.asset("p", "badge/hi").is_none());
+    }
+}

crates/ide-extension/src/when.rs

@@ -0,0 +1,136 @@
+//! Syntax check for `when` clauses in UI declarations. The client evaluates
+//! them (`src/platform/context.ts`); validating here keeps the client's
+//! projection from failing. Grammar (same as the client):
+//!
+//! ```text
+//! expr := or ; or := and ("||" and)* ; and := unary ("&&" unary)*
+//! unary := "!" unary | "(" expr ")" | cmp ; cmp := key (("==" | "!=") value)?
+//! ```
+
+const MAX_LEN: usize = 512;
+
+#[derive(Debug, PartialEq)]
+enum Tok<'a> {
+    Id(&'a str),
+    Str,
+    Op(&'a str),
+}
+
+fn tokenize(src: &str) -> Result<Vec<Tok<'_>>, String> {
+    let mut out = Vec::new();
+    let b = src.as_bytes();
+    let mut i = 0;
+    while i < b.len() {
+        let c = b[i] as char;
+        if c.is_whitespace() {
+            i += 1;
+        } else if ["&&", "||", "==", "!="].iter().any(|op| src[i..].starts_with(op)) {
+            out.push(Tok::Op(&src[i..i + 2]));
+            i += 2;
+        } else if matches!(c, '!' | '(' | ')') {
+            out.push(Tok::Op(&src[i..i + 1]));
+            i += 1;
+        } else if c == '\'' || c == '"' {
+            let end = src[i + 1..].find(c).ok_or_else(|| format!("unterminated string in when clause: {src}"))?;
+            out.push(Tok::Str);
+            i += end + 2;
+        } else {
+            let len = src[i..]
+                .find(|ch: char| !(ch.is_alphanumeric() || matches!(ch, '_' | '.' | '-' | ':' | '/')))
+                .unwrap_or(src.len() - i);
+            if len == 0 {
+                return Err(format!("unexpected '{c}' in when clause: {src}"));
+            }
+            out.push(Tok::Id(&src[i..i + len]));
+            i += len;
+        }
+    }
+    Ok(out)
+}
+
+/// Checks a `when` clause; empty means "always".
+pub fn validate_when(src: &str) -> Result<(), String> {
+    if src.len() > MAX_LEN {
+        return Err(format!("when clause longer than {MAX_LEN} bytes"));
+    }
+    if src.trim().is_empty() {
+        return Ok(());
+    }
+    let toks = tokenize(src)?;
+    let mut p = 0;
+    parse_or(&toks, &mut p, src)?;
+    if p != toks.len() {
+        return Err(format!("unexpected token in when clause: {src}"));
+    }
+    Ok(())
+}
+
+fn parse_or(t: &[Tok], p: &mut usize, src: &str) -> Result<(), String> {
+    parse_and(t, p, src)?;
+    while t.get(*p) == Some(&Tok::Op("||")) {
+        *p += 1;
+        parse_and(t, p, src)?;
+    }
+    Ok(())
+}
+
+fn parse_and(t: &[Tok], p: &mut usize, src: &str) -> Result<(), String> {
+    parse_unary(t, p, src)?;
+    while t.get(*p) == Some(&Tok::Op("&&")) {
+        *p += 1;
+        parse_unary(t, p, src)?;
+    }
+    Ok(())
+}
+
+fn parse_unary(t: &[Tok], p: &mut usize, src: &str) -> Result<(), String> {
+    match t.get(*p) {
+        Some(Tok::Op("!")) => {
+            *p += 1;
+            parse_unary(t, p, src)
+        }
+        Some(Tok::Op("(")) => {
+            *p += 1;
+            parse_or(t, p, src)?;
+            if t.get(*p) != Some(&Tok::Op(")")) {
+                return Err(format!("missing ')' in when clause: {src}"));
+            }
+            *p += 1;
+            Ok(())
+        }
+        Some(Tok::Id(_)) => {
+            *p += 1;
+            if matches!(t.get(*p), Some(Tok::Op("==" | "!="))) {
+                *p += 1;
+                match t.get(*p) {
+                    Some(Tok::Id(_) | Tok::Str) => *p += 1,
+                    _ => return Err(format!("missing value after comparison in when clause: {src}")),
+                }
+            }
+            Ok(())
+        }
+        _ => Err(format!("expected a context key in when clause: {src}")),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::validate_when;
+
+    #[test]
+    fn accepts_the_client_grammar() {
+        for ok in [
+            "",
+            "editorFocus",
+            "editorLang == rust",
+            "editorLang != 'rust' && !readOnly",
+            "(a || b) && toolWindow.project.active",
+            "resourceScheme == file:/x",
+        ] {
+            assert!(validate_when(ok).is_ok(), "{ok}");
+        }
+        for bad in ["a &&", "(a", "a == ", "== a", "a b", "a $ b", "'x", "!()"] {
+            assert!(validate_when(bad).is_err(), "{bad}");
+        }
+    }
+}

crates/ide-github/src/account.rs

@@ -0,0 +1,145 @@
+//! The signed-in GitHub account, independent of any project: its repositories for
+//! "Get from Version Control" › GitHub.
+
+use crate::{GhAvailability, QUICK, classify_failure, command, gh_executable, process};
+use serde::{Deserialize, Serialize};
+use specta::Type;
+
+/// A repository of the signed-in account (owned, collaborator, or organization member).
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct GhAccountRepo {
+    /// `owner/name`.
+    pub name_with_owner: String,
+    pub description: Option<String>,
+    pub private: bool,
+    pub fork: bool,
+    pub archived: bool,
+    /// What `git clone` takes: HTTPS, or SSH when gh's `git_protocol` is `ssh`.
+    pub clone_url: String,
+}
+
+/// The account's repositories, or why they can't be listed.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase", tag = "kind")]
+pub enum GhAccountRepos {
+    Ready {
+        login: String,
+        repos: Vec<GhAccountRepo>,
+    },
+    /// No `gh` executable was found.
+    NotInstalled,
+    /// `gh auth login` has not been run (or the token expired).
+    NotLoggedIn {
+        message: String,
+    },
+    Error {
+        message: String,
+    },
+}
+
+#[derive(Deserialize)]
+struct RestRepo {
+    full_name: String,
+    description: Option<String>,
+    #[serde(default)]
+    private: bool,
+    #[serde(default)]
+    fork: bool,
+    #[serde(default)]
+    archived: bool,
+    clone_url: String,
+    ssh_url: String,
+}
+
+/// `gh api --paginate --slurp user/repos` output: one array per page.
+pub fn parse_account_repos(slurped: &str, ssh: bool) -> Result<Vec<GhAccountRepo>, serde_json::Error> {
+    let pages: Vec<Vec<RestRepo>> = serde_json::from_str(slurped)?;
+    Ok(pages
+        .into_iter()
+        .flatten()
+        .map(|r| GhAccountRepo {
+            name_with_owner: r.full_name,
+            description: r.description.filter(|d| !d.trim().is_empty()),
+            private: r.private,
+            fork: r.fork,
+            archived: r.archived,
+            clone_url: if ssh { r.ssh_url } else { r.clone_url },
+        })
+        .collect())
+}
+
+/// Lists the repositories of the account gh is signed in to, most recently pushed first.
+pub fn account_repositories() -> GhAccountRepos {
+    if gh_executable().is_none() {
+        return GhAccountRepos::NotInstalled;
+    }
+    let dir = std::env::temp_dir();
+    let gh = |args: &[&str]| -> Result<String, GhAccountRepos> {
+        let out = command(&dir, args)
+            .and_then(|cmd| process::run(cmd, QUICK, None))
+            .map_err(|e| GhAccountRepos::Error { message: e.message })?;
+        if out.success {
+            return Ok(out.stdout);
+        }
+        let message = if out.stderr.trim().is_empty() { out.stdout } else { out.stderr };
+        Err(match classify_failure(&message) {
+            GhAvailability::NotLoggedIn { message } => GhAccountRepos::NotLoggedIn { message },
+            _ => GhAccountRepos::Error { message: message.trim().to_owned() },
+        })
+    };
+    let result = (|| {
+        let login = gh(&["api", "user", "--jq", ".login"])?.trim().to_owned();
+        let ssh = gh(&["config", "get", "git_protocol", "--host", "github.com"]).is_ok_and(|p| p.trim() == "ssh");
+        let pages = gh(&[
+            "api",
+            "user/repos?per_page=100&sort=pushed&affiliation=owner,collaborator,organization_member",
+            "--paginate",
+            "--slurp",
+        ])?;
+        let repos = parse_account_repos(&pages, ssh)
+            .map_err(|e| GhAccountRepos::Error { message: format!("unexpected gh output: {e}") })?;
+        Ok(GhAccountRepos::Ready { login, repos })
+    })();
+    result.unwrap_or_else(|e| e)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn reads_every_page_and_picks_the_configured_protocol() {
+        let pages = r#"[
+          [{"full_name":"me/app","description":"An app","private":true,"fork":false,"archived":false,
+            "clone_url":"https://github.com/me/app.git","ssh_url":"[email protected]:me/app.git"}],
+          [{"full_name":"org/lib","description":"","fork":true,
+            "clone_url":"https://github.com/org/lib.git","ssh_url":"[email protected]:org/lib.git"}]
+        ]"#;
+        let https = parse_account_repos(pages, false).unwrap();
+        assert_eq!(
+            https,
+            vec![
+                GhAccountRepo {
+                    name_with_owner: "me/app".into(),
+                    description: Some("An app".into()),
+                    private: true,
+                    fork: false,
+                    archived: false,
+                    clone_url: "https://github.com/me/app.git".into(),
+                },
+                GhAccountRepo {
+                    name_with_owner: "org/lib".into(),
+                    description: None,
+                    private: false,
+                    fork: true,
+                    archived: false,
+                    clone_url: "https://github.com/org/lib.git".into(),
+                },
+            ]
+        );
+        let ssh = parse_account_repos(pages, true).unwrap();
+        assert_eq!(ssh[1].clone_url, "[email protected]:org/lib.git");
+        assert!(parse_account_repos("[]", false).unwrap().is_empty());
+    }
+}

crates/ide-github/src/lib.rs

@@ -3,9 +3,11 @@
 //!
 //! Every function blocks; callers run them off the UI / command threads.
 
+mod account;
 mod model;
 mod process;
 
+pub use account::{GhAccountRepo, GhAccountRepos, account_repositories, parse_account_repos};
 pub use model::*;
 
 use ide_core::{CancellationToken, IdeError, IdeResult};

crates/ide-host/Cargo.toml

@@ -30,15 +30,24 @@ ide-terminal.workspace = true
 ide-run.workspace = true
 ide-sdk.workspace = true
 ide-http.workspace = true
+reqwest.workspace = true
+ignore.workspace = true
+base64.workspace = true
+getrandom = "0.3"
+globset.workspace = true
 ide-db.workspace = true
 ide-ssh.workspace = true
 ide-remote.workspace = true
 ide-jsonrpc.workspace = true
 ide-agent.workspace = true
 ide-notebook.workspace = true
+ide-extension.workspace = true
+ide-plugin.workspace = true
 ide-tools = { path = "../ide-tools" }
+ide-docker = { path = "../ide-docker" }
 serde.workspace = true
 serde_json.workspace = true
+toml.workspace = true
 specta.workspace = true
 specta-typescript.workspace = true
 tokio = { workspace = true, features = ["io-std"] }
@@ -53,9 +62,15 @@ tempfile.workspace = true
 [dev-dependencies]
 ide-ssh = { workspace = true, features = ["testing"] }
 tokio = { workspace = true, features = ["rt-multi-thread", "macros", "io-util", "test-util"] }
+criterion = { version = "0.5", default-features = false }
+zip.workspace = true
 
 [target.'cfg(unix)'.dependencies]
 rustix = { version = "1.1", features = ["fs", "process"] }
 
 [target.'cfg(windows)'.dependencies]
 windows-sys = { version = "0.61", features = ["Win32_Storage_FileSystem"] }
+
+[[bench]]
+name = "plugins"
+harness = false

crates/ide-host/benches/plugins.rs

@@ -0,0 +1,149 @@
+//! `cargo bench -p ide-host`: the plugin runtime budgets, checked by `pnpm perf:rust` against
+//! `perf/budgets.json` › rust (`plugins/…`).
+//!
+//! - `load_50`: start-up load of 50 installed plugins (20 with code, 10
+//!   languages with a syntax provider, 10 icon themes, 10 declarations only),
+//!   from the contribution index; no Wasm is instantiated.
+//! - `cold_activation`: an idle-reclaimed plugin's next command: activation
+//!   from the precompiled component plus the call.
+//! - `syntax_highlights_2k_lines`: an edit-path call (Solidity highlighting).
+
+use criterion::{Criterion, black_box, criterion_group, criterion_main};
+use ide_core::LanguageId;
+use ide_host::plugins::{Consent, PluginHost};
+use ide_plugin::{Invocation, Limits};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::time::Duration;
+
+fn repo() -> PathBuf {
+    Path::new(env!("CARGO_MANIFEST_DIR")).join("../..").canonicalize().unwrap()
+}
+
+fn copy_dir(from: &Path, to: &Path) {
+    std::fs::create_dir_all(to).unwrap();
+    for e in std::fs::read_dir(from).unwrap().flatten() {
+        let name = e.file_name();
+        if matches!(name.to_str(), Some("target" | "src" | "Cargo.lock" | ".gitignore")) {
+            continue;
+        }
+        let dst = to.join(&name);
+        if e.path().is_dir() { copy_dir(&e.path(), &dst) } else { std::fs::copy(e.path(), &dst).map(|_| ()).unwrap() }
+    }
+}
+
+/// A copy of `src` installed under a new id (and new language / theme ids).
+fn variant(work: &Path, src: &Path, n: usize, rename: &[(&str, String)]) -> PathBuf {
+    let dir = work.join(format!("pkg{n}"));
+    copy_dir(src, &dir);
+    for file in ["plugin.toml", "languages/solidity.toml"] {
+        let path = dir.join(file);
+        if let Ok(mut text) = std::fs::read_to_string(&path) {
+            for (from, to) in rename {
+                text = text.replace(from, to);
+            }
+            std::fs::write(&path, text).unwrap();
+        }
+    }
+    dir
+}
+
+fn sink() -> Arc<dyn ide_host::plugins::PluginEventSink> {
+    Arc::new(|_: Option<&str>, _| {})
+}
+
+fn install_50(plugins: &Path, work: &Path) {
+    let host = PluginHost::new(plugins.to_path_buf(), sink(), Limits::default()).unwrap();
+    host.load_all();
+    let root = repo();
+    let mut n = 0;
+    let mut install = |src: PathBuf, rename: Vec<(&str, String)>| {
+        let pkg = variant(work, &src, n, &rename);
+        n += 1;
+        host.install_from_dir(&pkg, &Consent::default()).unwrap();
+    };
+    for i in 0..20 {
+        install(
+            root.join("crates/ide-plugin/tests/fixtures/hello"),
+            vec![("id = \"hello\"", format!("id = \"bench.hello{i}\""))],
+        );
+    }
+    for i in 0..10 {
+        install(
+            root.join("plugins/official/solidity"),
+            vec![
+                ("openidea.solidity", format!("bench.solidity{i}")),
+                ("id = \"solidity\"", format!("id = \"solidity{i}\"")),
+                ("extensions = [\"sol\"]", format!("extensions = [\"sol{i}\"]")),
+                ("on-language:solidity", format!("on-language:solidity{i}")),
+                ("id = \"forge-", format!("id = \"f{i}-")),
+                ("id = \"hardhat-", format!("id = \"h{i}-")),
+            ],
+        );
+    }
+    for i in 0..10 {
+        install(
+            root.join("plugins/official/material-icons"),
+            vec![
+                ("openidea.material-icons", format!("bench.icons{i}")),
+                ("id = \"material\"", format!("id = \"material{i}\"")),
+            ],
+        );
+    }
+    for i in 0..10 {
+        let dir = work.join(format!("static{i}"));
+        std::fs::create_dir_all(&dir).unwrap();
+        std::fs::write(
+            dir.join("plugin.toml"),
+            format!(
+                "id = \"bench.static{i}\"\nname = \"Static {i}\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n\
+                 [[contributes.commands]]\nid = \"a\"\ntitle = \"Static {i}: A\"\nwhen = \"editorLang == rust\"\n"
+            ),
+        )
+        .unwrap();
+        host.install_from_dir(&dir, &Consent::default()).unwrap();
+    }
+}
+
+fn bench(c: &mut Criterion) {
+    let tmp = tempfile::tempdir().unwrap();
+    let plugins = tmp.path().join("plugins");
+    install_50(&plugins, &tmp.path().join("work"));
+
+    let mut g = c.benchmark_group("plugins");
+    g.sample_size(20);
+    g.bench_function("load_50", |b| {
+        b.iter(|| {
+            let host = PluginHost::new(plugins.clone(), sink(), Limits::default()).unwrap();
+            host.load_all();
+            assert_eq!(host.instances(), 0, "start-up instantiates no Wasm");
+            black_box(host.list(None).plugins.len())
+        })
+    });
+
+    let limits = Limits { idle_timeout: Some(Duration::ZERO), ..Limits::default() };
+    let host = Arc::new(PluginHost::new(plugins.clone(), sink(), limits).unwrap());
+    host.load_all();
+    host.warm_component_cache();
+    g.bench_function("cold_activation", |b| {
+        b.iter(|| {
+            host.tick();
+            // Fails for want of an editor, after activating and running.
+            let r = host.run_command("bench.hello0", "word-count", None, Invocation::default());
+            black_box(r.is_err())
+        })
+    });
+
+    let provider = host.syntax_provider();
+    let lang = LanguageId::new("solidity0");
+    let unit = "contract Token {\n    uint256 public total;\n    mapping(address => uint256) balances;\n    event Sent(address to, uint256 v);\n    function send(address to, uint256 v) public returns (bool) {\n        // move funds\n        balances[to] += v;\n        emit Sent(to, v);\n        return true;\n    }\n}\n";
+    let text = unit.repeat(2000 / unit.lines().count());
+    assert!(provider.highlights(&lang, &text).is_some());
+    g.bench_function("syntax_highlights_2k_lines", |b| {
+        b.iter(|| black_box(provider.highlights(&lang, &text).map(|t| t.len())))
+    });
+    g.finish();
+}
+
+criterion_group!(benches, bench);
+criterion_main!(benches);

crates/ide-host/src/bin/openidea-plugin/main.rs

@@ -0,0 +1,624 @@
+//! `openidea-plugin`: scaffolds, builds, checks and links OpenIDEA plugins.
+//!
+//! ```text
+//! openidea-plugin new <dir> [--template command|theme|icon-theme|language] [--id ID] [--name NAME] [--sdk PATH]
+//! openidea-plugin build [dir] [--debug]   # cargo → dist/plugin.wasm, then `check`
+//! openidea-plugin check [dir]             # validate the package as the IDE would install it
+//! openidea-plugin link [dir]              # load the folder in the IDE without installing it
+//! openidea-plugin unlink [dir]
+//! openidea-plugin links                   # list linked folders
+//! openidea-plugin keygen <key-file>       # a publisher's Ed25519 key
+//! openidea-plugin pack [dir] [--key F --publisher ID] [--out FILE]   # <id>-<version>.oiplugin
+//! openidea-plugin index <dir> --publisher ID --name NAME --key F     # marketplace index.json
+//! ```
+//!
+//! `link` writes `links.json` in the IDE's plugins directory
+//! (`$OPENIDEA_PLUGINS_DIR`, or the app data directory); the IDE picks the
+//! change up when Settings › Plugins is opened or refreshed. Linked plugins
+//! are re-read from the folder, so `build` + refresh is the edit loop.
+
+mod templates;
+
+use ide_extension::{Manifest, validate_plugin_id};
+use ide_host::plugins::PluginHost;
+use ide_plugin::{Limits, PluginEngine};
+use std::path::{Path, PathBuf};
+use std::process::{Command, ExitCode};
+use std::sync::Arc;
+
+const USAGE: &str = "\
+usage: openidea-plugin <command> [options]
+
+commands:
+  new <dir> [--template T] [--id ID] [--name NAME] [--sdk PATH]
+        create a plugin; T = command (default), theme, icon-theme, language
+  build [dir] [--debug]   compile a Rust plugin to dist/plugin.wasm and check it
+  check [dir]             validate the package as the IDE would install it
+  link [dir]              load the folder in the IDE without installing it
+  unlink [dir]            stop loading a linked folder
+  links                   list linked folders
+  keygen <key-file>       create a publisher signing key (keep the file secret)
+  pack [dir] [--key F --publisher ID] [--out FILE]
+                          write <id>-<version>.oiplugin, signed with the key
+  index <dir> --publisher ID --name NAME --key F [--out FILE]
+                          write the marketplace index.json for the packages in dir
+
+environment:
+  OPENIDEA_PLUGINS_DIR    the IDE's plugins directory (default: the app data directory)";
+
+fn main() -> ExitCode {
+    let args: Vec<String> = std::env::args().skip(1).collect();
+    let result = match args.first().map(String::as_str) {
+        Some("new") => cmd_new(&args[1..]),
+        Some("build") => cmd_build(&args[1..]),
+        Some("check") => dir_arg(&args[1..]).and_then(|d| check(&d)),
+        Some("link") => dir_arg(&args[1..]).and_then(|d| link(&d, true)),
+        Some("unlink") => dir_arg(&args[1..]).and_then(|d| link(&d, false)),
+        Some("links") => list_links(),
+        Some("keygen") => cmd_keygen(&args[1..]),
+        Some("pack") => cmd_pack(&args[1..]),
+        Some("index") => cmd_index(&args[1..]),
+        Some("--version" | "-V") => {
+            println!("openidea-plugin {} (plugin API {})", env!("CARGO_PKG_VERSION"), ide_extension::ENGINE_VERSION);
+            Ok(())
+        }
+        Some("help" | "--help" | "-h") | None => {
+            println!("{USAGE}");
+            Ok(())
+        }
+        Some(other) => Err(format!("unknown command {other:?}\n\n{USAGE}")),
+    };
+    match result {
+        Ok(()) => ExitCode::SUCCESS,
+        Err(e) => {
+            eprintln!("error: {e}");
+            ExitCode::FAILURE
+        }
+    }
+}
+
+/// Splits `args` into positionals and `--flag value` / `--switch` options.
+struct Args {
+    positional: Vec<String>,
+    options: Vec<(String, Option<String>)>,
+}
+
+impl Args {
+    fn parse(args: &[String], switches: &[&str], valued: &[&str]) -> Result<Self, String> {
+        let mut out = Args { positional: Vec::new(), options: Vec::new() };
+        let mut it = args.iter();
+        while let Some(a) = it.next() {
+            if let Some(name) = a.strip_prefix("--") {
+                let (name, inline) = match name.split_once('=') {
+                    Some((n, v)) => (n, Some(v.to_owned())),
+                    None => (name, None),
+                };
+                if switches.contains(&name) && inline.is_none() {
+                    out.options.push((name.into(), None));
+                } else if valued.contains(&name) {
+                    let v = inline.or_else(|| it.next().cloned()).ok_or_else(|| format!("--{name} needs a value"))?;
+                    out.options.push((name.into(), Some(v)));
+                } else {
+                    return Err(format!("unknown option --{name}"));
+                }
+            } else {
+                out.positional.push(a.clone());
+            }
+        }
+        Ok(out)
+    }
+
+    fn value(&self, name: &str) -> Option<&str> {
+        self.options.iter().rev().find(|(n, _)| n == name).and_then(|(_, v)| v.as_deref())
+    }
+
+    fn has(&self, name: &str) -> bool {
+        self.options.iter().any(|(n, _)| n == name)
+    }
+
+    fn dir(&self) -> Result<PathBuf, String> {
+        match self.positional.as_slice() {
+            [] => Ok(PathBuf::from(".")),
+            [d] => Ok(PathBuf::from(d)),
+            _ => Err("expected at most one directory".into()),
+        }
+    }
+}
+
+fn dir_arg(args: &[String]) -> Result<PathBuf, String> {
+    Args::parse(args, &[], &[])?.dir()
+}
+
+fn canonical(dir: &Path) -> Result<PathBuf, String> {
+    dunce::canonicalize(dir).map_err(|e| format!("{}: {e}", dir.display()))
+}
+
+// ---------------------------------------------------------------- new
+
+fn cmd_new(args: &[String]) -> Result<(), String> {
+    let a = Args::parse(args, &[], &["template", "id", "name", "sdk"])?;
+    let [dir] = a.positional.as_slice() else {
+        return Err("usage: openidea-plugin new <dir> [--template T] [--id ID] [--name NAME]".into());
+    };
+    let dir = PathBuf::from(dir);
+    let template = templates::Template::parse(a.value("template").unwrap_or("command"))?;
+    let base = dir.file_name().and_then(|n| n.to_str()).ok_or("the directory needs a name")?;
+    let id = match a.value("id") {
+        Some(id) => id.to_owned(),
+        None => slugify(base),
+    };
+    validate_plugin_id(&id)?;
+    let name = match a.value("name") {
+        Some(n) => n.to_owned(),
+        None => title_case(id.rsplit('.').next().unwrap_or(&id)),
+    };
+    if name.trim().is_empty() || name.contains(['"', '\\', '\n']) {
+        return Err("--name must not be empty or contain quotes, backslashes or newlines".into());
+    }
+    if dir.exists() && std::fs::read_dir(&dir).map_err(|e| e.to_string())?.next().is_some() {
+        return Err(format!("{} already exists and is not empty", dir.display()));
+    }
+    std::fs::create_dir_all(&dir).map_err(|e| format!("{}: {e}", dir.display()))?;
+    let dir = canonical(&dir)?;
+    let sdk = match template {
+        templates::Template::Command => Some(sdk_path(a.value("sdk"), &dir)?),
+        _ => None,
+    };
+    let vars = templates::Vars { id: &id, name: &name, sdk: sdk.as_deref() };
+    let files = templates::render(template, &vars);
+    for (rel, content) in &files {
+        let path = dir.join(rel);
+        if let Some(parent) = path.parent() {
+            std::fs::create_dir_all(parent).map_err(|e| format!("{}: {e}", parent.display()))?;
+        }
+        std::fs::write(&path, content).map_err(|e| format!("{}: {e}", path.display()))?;
+    }
+    // Generated packages must be valid as written.
+    Manifest::load(&dir).map_err(|e| format!("internal error: the template is invalid: {e}"))?;
+    println!("created {} ({id}) in {}", template.label(), dir.display());
+    let shown = std::env::current_dir().ok().and_then(|cwd| dir.strip_prefix(cwd).ok().map(Path::to_path_buf));
+    let shown = shown.as_deref().unwrap_or(&dir).display().to_string();
+    println!();
+    println!("next:");
+    if template == templates::Template::Command {
+        println!("  cargo test --manifest-path {shown}/Cargo.toml   # unit tests against the mock host");
+        println!("  openidea-plugin build {shown}");
+    } else {
+        println!("  openidea-plugin check {shown}");
+    }
+    println!("  openidea-plugin link {shown}                  # then Settings › Plugins");
+    Ok(())
+}
+
+/// `My Cool_Plugin` → `my-cool-plugin`.
+fn slugify(s: &str) -> String {
+    let mut out = String::new();
+    for c in s.chars() {
+        match c {
+            'a'..='z' | '0'..='9' | '.' => out.push(c),
+            'A'..='Z' => out.push(c.to_ascii_lowercase()),
+            _ if !out.ends_with('-') && !out.is_empty() => out.push('-'),
+            _ => {}
+        }
+    }
+    out.trim_matches(['-', '.']).to_owned()
+}
+
+/// `my-cool_plugin` → `My Cool Plugin`.
+fn title_case(s: &str) -> String {
+    s.split(['-', '_'])
+        .filter(|w| !w.is_empty())
+        .map(|w| {
+            let mut c = w.chars();
+            c.next().map(|f| f.to_uppercase().chain(c).collect::<String>()).unwrap_or_default()
+        })
+        .collect::<Vec<_>>()
+        .join(" ")
+}
+
+/// The SDK dependency path written into a new plugin's Cargo.toml: `--sdk`,
+/// or the SDK of the source tree this tool was built from.
+fn sdk_path(explicit: Option<&str>, plugin_dir: &Path) -> Result<String, String> {
+    let sdk = match explicit {
+        Some(p) => PathBuf::from(p),
+        None => PathBuf::from(concat!(env!("CARGO_MANIFEST_DIR"), "/../../sdk/rust/openidea-plugin")),
+    };
+    let sdk = dunce::canonicalize(&sdk).map_err(|_| {
+        format!("the plugin SDK was not found at {}; pass --sdk <path to sdk/rust/openidea-plugin>", sdk.display())
+    })?;
+    if !sdk.join("Cargo.toml").is_file() {
+        return Err(format!("{} is not the openidea-plugin SDK (no Cargo.toml)", sdk.display()));
+    }
+    let path = relative(plugin_dir, &sdk).unwrap_or(sdk);
+    Ok(path.to_string_lossy().replace('\\', "/"))
+}
+
+/// `to` relative to `from` when they share a root (keeps packages in a repo movable).
+fn relative(from: &Path, to: &Path) -> Option<PathBuf> {
+    let (f, t): (Vec<_>, Vec<_>) = (from.components().collect(), to.components().collect());
+    let common = f.iter().zip(&t).take_while(|(a, b)| a == b).count();
+    if common <= 1 {
+        return None;
+    }
+    let mut out = PathBuf::new();
+    for _ in common..f.len() {
+        out.push("..");
+    }
+    for c in &t[common..] {
+        out.push(c);
+    }
+    Some(out)
+}
+
+// ---------------------------------------------------------------- build / check
+
+fn cmd_build(args: &[String]) -> Result<(), String> {
+    let a = Args::parse(args, &["debug"], &[])?;
+    let dir = canonical(&a.dir()?)?;
+    let manifest = Manifest::load(&dir)?;
+    let cargo_toml = dir.join("Cargo.toml");
+    if !cargo_toml.is_file() {
+        if manifest.wasm.is_some() {
+            return Err(format!(
+                "{} has no Cargo.toml: build the component with your toolchain, then run `check`",
+                dir.display()
+            ));
+        }
+        println!("{} has no code to build", manifest.id);
+        return check(&dir);
+    }
+    let wasm_rel = manifest.wasm.clone().ok_or("plugin.toml has no `wasm = \"dist/plugin.wasm\"`")?;
+    let crate_name = crate_name(&cargo_toml)?;
+    ensure_wasm_target();
+    let release = !a.has("debug");
+    let target_dir = std::env::var_os("CARGO_TARGET_DIR").map(PathBuf::from).unwrap_or_else(|| dir.join("target"));
+    let mut cmd = Command::new(std::env::var_os("CARGO").unwrap_or_else(|| "cargo".into()));
+    cmd.arg("build").arg("--manifest-path").arg(&cargo_toml).args(["--target", "wasm32-wasip2"]);
+    if release {
+        cmd.arg("--release");
+    }
+    cmd.env("CARGO_TARGET_DIR", &target_dir);
+    println!("building {crate_name} for wasm32-wasip2 ({})", if release { "release" } else { "debug" });
+    let status = cmd.status().map_err(|e| format!("cannot run cargo: {e}"))?;
+    if !status.success() {
+        return Err("cargo build failed".into());
+    }
+    let built = target_dir
+        .join("wasm32-wasip2")
+        .join(if release { "release" } else { "debug" })
+        .join(format!("{}.wasm", crate_name.replace('-', "_")));
+    if !built.is_file() {
+        return Err(format!("{} was not produced: is `crate-type = [\"cdylib\"]` set in Cargo.toml?", built.display()));
+    }
+    let out = dir.join(&wasm_rel);
+    if let Some(parent) = out.parent() {
+        std::fs::create_dir_all(parent).map_err(|e| format!("{}: {e}", parent.display()))?;
+    }
+    std::fs::copy(&built, &out).map_err(|e| format!("{}: {e}", out.display()))?;
+    let size = std::fs::metadata(&out).map(|m| m.len()).unwrap_or(0);
+    println!("  -> {} ({})", wasm_rel.display(), human_size(size));
+    check(&dir)
+}
+
+fn crate_name(cargo_toml: &Path) -> Result<String, String> {
+    let src = std::fs::read_to_string(cargo_toml).map_err(|e| format!("{}: {e}", cargo_toml.display()))?;
+    let doc: toml::Table = src.parse().map_err(|e| format!("{}: {e}", cargo_toml.display()))?;
+    let package = doc.get("package").and_then(|p| p.as_table());
+    let lib_name = doc.get("lib").and_then(|l| l.get("name")).and_then(|n| n.as_str());
+    lib_name
+        .or_else(|| package.and_then(|p| p.get("name")).and_then(|n| n.as_str()))
+        .map(str::to_owned)
+        .ok_or_else(|| format!("{}: no [package] name", cargo_toml.display()))
+}
+
+/// Installs the target through rustup when it is missing (no-op without rustup).
+fn ensure_wasm_target() {
+    let Ok(out) = Command::new("rustup").args(["target", "list", "--installed"]).output() else { return };
+    if String::from_utf8_lossy(&out.stdout).lines().any(|l| l.trim() == "wasm32-wasip2") {
+        return;
+    }
+    println!("installing the wasm32-wasip2 target");
+    let _ = Command::new("rustup").args(["target", "add", "wasm32-wasip2"]).status();
+}
+
+/// Validates `dir` exactly as Install from Disk would, and checks the
+/// component imports only the plugin API.
+fn check(dir: &Path) -> Result<(), String> {
+    let dir = canonical(dir)?;
+    let scratch = std::env::temp_dir().join(format!("openidea-plugin-check-{}", std::process::id()));
+    let result = (|| {
+        let host = PluginHost::new(scratch.clone(), Arc::new(|_: Option<&str>, _| {}), Limits::default())
+            .map_err(|e| e.to_string())?;
+        let preview = host.preview_install(&dir).map_err(|e| e.to_string())?;
+        let manifest = Manifest::load(&dir)?;
+        println!("{} {} — {}", preview.id, preview.version, preview.name);
+        if manifest.legacy {
+            println!("  note: plugin.toml uses the 0.1 format (`openidea-api`); see plugins/README.md to move to 0.2");
+        }
+        if let Some(wasm) = &manifest.wasm {
+            let engine = PluginEngine::new()?;
+            let component = engine.compile(&dir.join(wasm))?;
+            let built_for = engine.check_component(&component)?;
+            let size = std::fs::metadata(dir.join(wasm)).map(|m| m.len()).unwrap_or(0);
+            let api = built_for.map(|v| format!(", plugin API {}.{}", v.major, v.minor)).unwrap_or_default();
+            println!("  code: {} ({}{api})", wasm.display(), human_size(size));
+        } else {
+            println!("  code: none (contributions only)");
+        }
+        if !manifest.activation.is_empty() {
+            let events: Vec<String> = manifest.activation.iter().map(ToString::to_string).collect();
+            println!("  activation: {}", events.join(", "));
+        }
+        for c in &preview.contributions {
+            println!("  contributes {} × {}", c.count, c.point);
+        }
+        for c in &preview.capabilities {
+            let kind = if c.optional { "optional" } else { "required" };
+            println!("  capability {} ({kind}, {:?} risk): {}", c.id, c.risk, c.description);
+        }
+        for w in &preview.warnings {
+            println!("  warning: {w}");
+        }
+        println!("ok");
+        Ok(())
+    })();
+    let _ = std::fs::remove_dir_all(&scratch);
+    result
+}
+
+fn human_size(bytes: u64) -> String {
+    match bytes {
+        b if b >= 1 << 20 => format!("{:.1} MiB", b as f64 / (1 << 20) as f64),
+        b if b >= 1 << 10 => format!("{:.1} KiB", b as f64 / 1024.0),
+        b => format!("{b} B"),
+    }
+}
+
+// ---------------------------------------------------------------- link
+
+fn plugins_dir() -> Result<PathBuf, String> {
+    if let Some(dir) = std::env::var_os("OPENIDEA_PLUGINS_DIR") {
+        return Ok(PathBuf::from(dir));
+    }
+    dirs::data_dir()
+        .map(|d| d.join("ai.l0ng.openidea").join("plugins"))
+        .ok_or_else(|| "cannot find the app data directory; set OPENIDEA_PLUGINS_DIR".into())
+}
+
+#[derive(Default, serde::Serialize, serde::Deserialize)]
+struct Links {
+    #[serde(default)]
+    paths: Vec<PathBuf>,
+}
+
+fn read_links(file: &Path) -> Result<Links, String> {
+    match std::fs::read_to_string(file) {
+        Ok(s) => serde_json::from_str(&s).map_err(|e| format!("{}: {e}", file.display())),
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(Links::default()),
+        Err(e) => Err(format!("{}: {e}", file.display())),
+    }
+}
+
+fn link(dir: &Path, add: bool) -> Result<(), String> {
+    let plugins = plugins_dir()?;
+    let file = plugins.join("links.json");
+    let mut links = read_links(&file)?;
+    let dir = if add {
+        let dir = canonical(dir)?;
+        let m = Manifest::load(&dir)?;
+        if let Some(wasm) = &m.wasm
+            && !dir.join(wasm).is_file()
+        {
+            println!("note: {} does not exist yet; run `openidea-plugin build` first", wasm.display());
+        }
+        if links.paths.contains(&dir) {
+            println!("{} is already linked", dir.display());
+            return Ok(());
+        }
+        println!("linked {} ({})", m.id, dir.display());
+        links.paths.push(dir.clone());
+        dir
+    } else {
+        let dir = dunce::canonicalize(dir).unwrap_or_else(|_| dir.to_path_buf());
+        let before = links.paths.len();
+        links.paths.retain(|p| p != &dir);
+        if links.paths.len() == before {
+            return Err(format!("{} is not linked", dir.display()));
+        }
+        println!("unlinked {}", dir.display());
+        dir
+    };
+    let _ = dir;
+    std::fs::create_dir_all(&plugins).map_err(|e| format!("{}: {e}", plugins.display()))?;
+    let json = serde_json::to_string_pretty(&links).map_err(|e| e.to_string())?;
+    let tmp = file.with_extension("json.tmp");
+    std::fs::write(&tmp, json)
+        .and_then(|()| std::fs::rename(&tmp, &file))
+        .map_err(|e| format!("{}: {e}", file.display()))?;
+    println!("open Settings › Plugins in OpenIDEA to load the change");
+    Ok(())
+}
+
+fn list_links() -> Result<(), String> {
+    let links = read_links(&plugins_dir()?.join("links.json"))?;
+    if links.paths.is_empty() {
+        println!("no linked plugins");
+    }
+    for p in links.paths {
+        let id = Manifest::load(&p).map(|m| m.id).unwrap_or_else(|e| format!("invalid: {e}"));
+        println!("{id}\t{}", p.display());
+    }
+    Ok(())
+}
+
+// ---------------------------------------------------------------- distribution
+
+use ide_extension::package::{self, Index, IndexEntry, KeyEntry, PublisherKey};
+
+fn read_key(path: &str) -> Result<PublisherKey, String> {
+    PublisherKey::from_base64(&std::fs::read_to_string(path).map_err(|e| format!("{path}: {e}"))?)
+}
+
+fn cmd_keygen(args: &[String]) -> Result<(), String> {
+    let a = Args::parse(args, &[], &[])?;
+    let [file] = a.positional.as_slice() else { return Err("usage: openidea-plugin keygen <key-file>".into()) };
+    if Path::new(file).exists() {
+        return Err(format!("{file} exists; not overwriting a key"));
+    }
+    let mut seed = [0u8; 32];
+    getrandom::fill(&mut seed).map_err(|e| format!("random: {e}"))?;
+    let key = PublisherKey::from_seed(seed);
+    std::fs::write(file, key.seed_base64()).map_err(|e| format!("{file}: {e}"))?;
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        let _ = std::fs::set_permissions(file, std::fs::Permissions::from_mode(0o600));
+    }
+    println!("public key: {}", key.public_base64());
+    println!("register it with your publisher id in the marketplace index; keep {file} secret");
+    Ok(())
+}
+
+/// A scratch host to list a package's files as the IDE would.
+fn with_scratch_host<T>(f: impl FnOnce(&PluginHost) -> Result<T, String>) -> Result<T, String> {
+    let scratch = std::env::temp_dir().join(format!("openidea-plugin-pack-{}", std::process::id()));
+    let result = PluginHost::new(scratch.clone(), Arc::new(|_: Option<&str>, _| {}), Limits::default())
+        .map_err(|e| e.to_string())
+        .and_then(|h| f(&h));
+    let _ = std::fs::remove_dir_all(&scratch);
+    result
+}
+
+fn cmd_pack(args: &[String]) -> Result<(), String> {
+    let a = Args::parse(args, &[], &["key", "publisher", "out"])?;
+    let dir = canonical(&a.dir()?)?;
+    check(&dir)?;
+    let manifest = Manifest::load(&dir)?;
+    let mut files = with_scratch_host(|h| h.package_files_of(&dir).map_err(|e| e.to_string()))?;
+    let digest = package::package_digest(&dir, &files).map_err(|e| e.to_string())?;
+    let signature = match (a.value("key"), a.value("publisher")) {
+        (Some(key), Some(publisher)) => {
+            if !manifest.id.starts_with(&format!("{publisher}.")) {
+                return Err(format!("publisher {publisher:?} may only sign plugins named {publisher}.*"));
+            }
+            Some(read_key(key)?.sign(publisher, &manifest.id, &manifest.version, &digest))
+        }
+        (None, None) => None,
+        _ => return Err("--key and --publisher go together".into()),
+    };
+    for lic in ["LICENSE", "LICENSE.md", "LICENSE.txt", "NOTICE", "NOTICE.md", "COPYING", "README.md"] {
+        if dir.join(lic).is_file() {
+            files.push(PathBuf::from(lic));
+        }
+    }
+    let out = a.value("out").map(PathBuf::from).unwrap_or_else(|| {
+        PathBuf::from(format!("{}-{}.{}", manifest.id, manifest.version, package::PACKAGE_EXTENSION))
+    });
+    package::pack(&dir, &files, &out, signature.as_ref())?;
+    let size = std::fs::metadata(&out).map(|m| m.len()).unwrap_or(0);
+    let signed = signature.as_ref().map_or("unsigned".to_owned(), |s| format!("signed by {}", s.publisher));
+    println!("-> {} ({}, {signed})", out.display(), human_size(size));
+    Ok(())
+}
+
+fn cmd_index(args: &[String]) -> Result<(), String> {
+    let a = Args::parse(args, &[], &["publisher", "name", "key", "out"])?;
+    let dir = canonical(&a.dir()?)?;
+    let publisher = a.value("publisher").ok_or("--publisher is required")?;
+    let name = a.value("name").unwrap_or(publisher);
+    let key = read_key(a.value("key").ok_or("--key is required")?)?;
+    let out = a.value("out").map(PathBuf::from).unwrap_or_else(|| dir.join("index.json"));
+    // Revocations and other publishers of an existing index are kept.
+    let mut index = match std::fs::read_to_string(&out) {
+        Ok(text) => Index::parse(&text)?,
+        Err(_) => Index { format: package::INDEX_FORMAT, ..Index::default() },
+    };
+    // Earlier keys of the publisher stay listed (packages they signed remain valid until revoked).
+    let current = key.public_base64();
+    let earlier: Vec<KeyEntry> = index
+        .publishers
+        .iter()
+        .filter(|p| p.id == publisher)
+        .flat_map(|p| p.keys.iter().filter(|k| k.key != current).cloned())
+        .collect();
+    index.publishers.retain(|p| p.id != publisher);
+    let keys: Vec<KeyEntry> = std::iter::once(KeyEntry { key: current, revoked: false }).chain(earlier).collect();
+    index.publishers.push(package::Publisher { id: publisher.into(), name: name.into(), keys });
+    index.plugins.clear();
+    let mut packages: Vec<PathBuf> = std::fs::read_dir(&dir)
+        .map_err(|e| e.to_string())?
+        .flatten()
+        .map(|e| e.path())
+        .filter(|p| p.extension().is_some_and(|e| e == package::PACKAGE_EXTENSION))
+        .collect();
+    packages.sort();
+    for path in packages {
+        let scratch = std::env::temp_dir().join(format!("openidea-plugin-index-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&scratch);
+        let unpacked = package::unpack(&path, &scratch)?;
+        let entry = (|| {
+            let m = Manifest::load(&scratch)?;
+            let files = with_scratch_host(|h| h.package_files_of(&scratch).map_err(|e| e.to_string()))?;
+            let digest = package::package_digest(&scratch, &files).map_err(|e| e.to_string())?;
+            let sig = unpacked.signature.as_ref().ok_or_else(|| format!("{}: not signed", path.display()))?;
+            sig.check(&m.id, &m.version, &digest).map_err(|e| format!("{}: {e}", path.display()))?;
+            Ok::<_, String>(IndexEntry {
+                id: m.id.clone(),
+                name: m.name.clone(),
+                version: m.version.clone(),
+                description: m.description.clone(),
+                authors: m.authors.clone(),
+                publisher: sig.publisher.clone(),
+                download: path.file_name().map(|n| n.to_string_lossy().into_owned()).unwrap_or_default(),
+                digest,
+                capabilities: m.capabilities.all().map(|c| c.to_string()).collect(),
+            })
+        })();
+        let _ = std::fs::remove_dir_all(&scratch);
+        let entry = entry?;
+        println!("  {} {}", entry.id, entry.version);
+        index.plugins.push(entry);
+    }
+    let json = serde_json::to_string_pretty(&index).map_err(|e| e.to_string())?;
+    std::fs::write(&out, json).map_err(|e| format!("{}: {e}", out.display()))?;
+    println!("-> {} ({} plugins)", out.display(), index.plugins.len());
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn names() {
+        assert_eq!(slugify("My Cool_Plugin"), "my-cool-plugin");
+        assert_eq!(slugify("acme.Tools"), "acme.tools");
+        assert_eq!(title_case("material-icons"), "Material Icons");
+        assert_eq!(
+            relative(Path::new("/a/b/plugins/x"), Path::new("/a/b/sdk/rust/p")).unwrap(),
+            PathBuf::from("../../sdk/rust/p")
+        );
+        assert_eq!(relative(Path::new("/x/y"), Path::new("/z")), None);
+    }
+
+    #[test]
+    fn every_template_is_a_valid_package() {
+        for t in templates::Template::ALL {
+            let dir =
+                std::env::temp_dir().join(format!("openidea-plugin-template-{}-{}", t.label(), std::process::id()));
+            let _ = std::fs::remove_dir_all(&dir);
+            let vars = templates::Vars { id: "acme.sample", name: "Sample", sdk: Some("../sdk") };
+            for (rel, content) in templates::render(t, &vars) {
+                let path = dir.join(rel);
+                std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+                std::fs::write(path, content).unwrap();
+            }
+            let m = Manifest::load(&dir).unwrap_or_else(|e| panic!("{}: {e}", t.label()));
+            assert_eq!(m.id, "acme.sample");
+            if m.wasm.is_none() {
+                check(&dir).unwrap_or_else(|e| panic!("{}: {e}", t.label()));
+            }
+            std::fs::remove_dir_all(&dir).unwrap();
+        }
+    }
+}

crates/ide-host/src/bin/openidea-plugin/templates.rs

@@ -0,0 +1,278 @@
+//! The files of `openidea-plugin new`. Placeholders: `__ID__` (plugin id),
+//! `__SLUG__` (last id segment), `__NAME__`, `__CRATE__`, `__SDK__`.
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum Template {
+    Command,
+    Theme,
+    IconTheme,
+    Language,
+}
+
+impl Template {
+    pub const ALL: [Template; 4] = [Self::Command, Self::Theme, Self::IconTheme, Self::Language];
+
+    pub fn parse(s: &str) -> Result<Self, String> {
+        Self::ALL
+            .into_iter()
+            .find(|t| t.label() == s)
+            .ok_or_else(|| format!("unknown template {s:?} (command, theme, icon-theme, language)"))
+    }
+
+    pub fn label(self) -> &'static str {
+        match self {
+            Self::Command => "command",
+            Self::Theme => "theme",
+            Self::IconTheme => "icon-theme",
+            Self::Language => "language",
+        }
+    }
+}
+
+pub struct Vars<'a> {
+    pub id: &'a str,
+    pub name: &'a str,
+    pub sdk: Option<&'a str>,
+}
+
+/// `(relative path, contents)` of every file of the template.
+pub fn render(template: Template, vars: &Vars) -> Vec<(String, String)> {
+    let slug = vars.id.rsplit('.').next().unwrap_or(vars.id).to_owned();
+    let crate_name = format!("openidea-plugin-{}", vars.id.replace('.', "-"));
+    let fill = |s: &str| {
+        s.replace("__ID__", vars.id)
+            .replace("__SLUG__", &slug)
+            .replace("__NAME__", vars.name)
+            .replace("__CRATE__", &crate_name)
+            .replace("__SDK__", vars.sdk.unwrap_or(""))
+            // The theme files come from the Harbor Night plugin.
+            .replace("harbor-night", &slug)
+            .replace("Harbor Night", vars.name)
+    };
+    let files: Vec<(String, &str)> = match template {
+        Template::Command => vec![
+            ("plugin.toml".into(), COMMAND_MANIFEST),
+            ("Cargo.toml".into(), COMMAND_CARGO),
+            ("src/lib.rs".into(), COMMAND_LIB),
+            (".gitignore".into(), "/target\n"),
+            ("README.md".into(), COMMAND_README),
+        ],
+        Template::Theme => vec![
+            ("plugin.toml".into(), THEME_MANIFEST),
+            (format!("themes/{slug}.theme.json"), THEME_UI),
+            (format!("themes/{slug}.scheme.json"), THEME_SCHEME),
+        ],
+        Template::IconTheme => vec![
+            ("plugin.toml".into(), ICON_MANIFEST),
+            ("icons/theme.json".into(), ICON_THEME),
+            ("icons/file.svg".into(), ICON_FILE),
+            ("icons/folder.svg".into(), ICON_FOLDER),
+            ("icons/folder-open.svg".into(), ICON_FOLDER_OPEN),
+            ("icons/markdown.svg".into(), ICON_MARKDOWN),
+        ],
+        Template::Language => {
+            vec![("plugin.toml".into(), LANGUAGE_MANIFEST), (format!("languages/{slug}.toml"), LANGUAGE_DEF)]
+        }
+    };
+    files.into_iter().map(|(path, content)| (path, fill(content))).collect()
+}
+
+const COMMAND_MANIFEST: &str = r#"id = "__ID__"
+name = "__NAME__"
+version = "0.1.0"
+description = "Adds two sample commands."
+authors = []
+engines.openidea = "^1.0"
+# Built by `openidea-plugin build`. The code is loaded the first time one of
+# its commands runs; the commands below show in Find Action before that.
+wasm = "dist/plugin.wasm"
+
+# What the code may do. The user approves these when installing.
+[capabilities]
+required = ["editor.read"]
+
+[[contributes.commands]]
+id = "say-hello"
+title = "__NAME__: Say Hello"
+category = "__NAME__"
+
+[[contributes.commands]]
+id = "line-count"
+title = "__NAME__: Line Count of Active File"
+category = "__NAME__"
+"#;
+
+const COMMAND_CARGO: &str = r#"[package]
+name = "__CRATE__"
+version = "0.1.0"
+edition = "2024"
+publish = false
+
+# A plugin builds on its own (target wasm32-wasip2), outside any IDE workspace.
+[workspace]
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+openidea-plugin = { path = "__SDK__" }
+
+[profile.release]
+opt-level = "s"
+lto = true
+strip = true
+codegen-units = 1
+panic = "abort"
+"#;
+
+const COMMAND_LIB: &str = r#"//! __NAME__: an OpenIDEA plugin.
+
+use openidea_plugin::{Invocation, NotificationLevel, Plugin, host, register_plugin};
+
+#[derive(Default)]
+pub struct Main {
+    greetings: u32,
+}
+
+impl Plugin for Main {
+    fn run_command(&mut self, id: &str, ctx: &Invocation, _arg: Option<&str>) -> Result<Option<String>, String> {
+        match id {
+            "say-hello" => {
+                // Instance state lasts until the plugin is idle for a while;
+                // keep what must survive in `host::storage`.
+                self.greetings += 1;
+                let body = format!("Hello #{} from __NAME__!", self.greetings);
+                host::notify(NotificationLevel::Info, "__NAME__", &body);
+                Ok(None)
+            }
+            "line-count" => {
+                let editor = ctx.editor().ok_or("no file is open")?;
+                let text = editor.document()?.text;
+                Ok(Some(format!("{} lines in {}", text.lines().count(), editor.path())))
+            }
+            _ => Err(format!("unknown command {id}")),
+        }
+    }
+}
+
+register_plugin!(Main);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use openidea_plugin::mock::MockHost;
+
+    #[test]
+    fn says_hello() {
+        let host = MockHost::install();
+        let mut plugin = Main::default();
+        plugin.run_command("say-hello", &host.invocation(), None).unwrap();
+        plugin.run_command("say-hello", &host.invocation(), None).unwrap();
+        assert_eq!(host.notifications()[1].body, "Hello #2 from __NAME__!");
+    }
+
+    #[test]
+    fn counts_lines() {
+        let host = MockHost::install();
+        host.open_editor("/project/src/main.rs", "rust", "fn main() {\n}\n", &[]);
+        let out = Main::default().run_command("line-count", &host.invocation(), None).unwrap();
+        assert_eq!(out.as_deref(), Some("2 lines in /project/src/main.rs"));
+    }
+}
+"#;
+
+const COMMAND_README: &str = r#"# __NAME__
+
+An OpenIDEA plugin.
+
+```sh
+cargo test                       # logic, against the SDK's mock host
+openidea-plugin build            # → dist/plugin.wasm, validated like an install
+openidea-plugin link             # load this folder in the IDE (Settings › Plugins)
+```
+
+`plugin.toml` declares the commands, so they appear in Find Action before the
+code is loaded, and the capabilities the code needs. `src/lib.rs` implements
+them with the `openidea-plugin` SDK.
+"#;
+
+const THEME_MANIFEST: &str = r#"id = "__ID__"
+name = "__NAME__"
+version = "0.1.0"
+description = "A dark theme."
+authors = []
+engines.openidea = "^1.0"
+
+# One entry per theme. `editor-scheme` is optional: its tokens are merged over
+# the theme's (IntelliJ's .theme.json + .icls pair). Reference: docs/plugins/themes.md.
+[[contributes.themes]]
+path = "themes/__SLUG__.theme.json"
+editor-scheme = "themes/__SLUG__.scheme.json"
+"#;
+
+const THEME_UI: &str = include_str!("../../../../../plugins/official/harbor-night/themes/harbor-night.theme.json");
+const THEME_SCHEME: &str = include_str!("../../../../../plugins/official/harbor-night/themes/harbor-night.scheme.json");
+
+const ICON_MANIFEST: &str = r#"id = "__ID__"
+name = "__NAME__"
+version = "0.1.0"
+description = "File and folder icons."
+authors = []
+engines.openidea = "^1.0"
+
+# Apply it in Settings › Plugins › __NAME__. SVGs are sanitised on install:
+# no scripts, event handlers, external references or entities.
+[[contributes.iconThemes]]
+id = "__SLUG__"
+label = "__NAME__"
+path = "icons/theme.json"
+"#;
+
+const ICON_THEME: &str = r#"{
+  "iconDefinitions": {
+    "file": "icons/file.svg",
+    "folder": "icons/folder.svg",
+    "folder-open": "icons/folder-open.svg",
+    "markdown": "icons/markdown.svg"
+  },
+  "file": "file",
+  "folder": "folder",
+  "folderExpanded": "folder-open",
+  "fileExtensions": { "md": "markdown", "markdown": "markdown" },
+  "fileNames": { "readme": "markdown" },
+  "folderNames": {}
+}
+"#;
+
+const ICON_FILE: &str = r##"<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><path fill="#90a4ae" d="M4 1.5h5.5L13 5v9.5H4z"/><path fill="#cfd8dc" d="M9.5 1.5V5H13z"/></svg>
+"##;
+
+const ICON_FOLDER: &str = r##"<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><path fill="#90a4ae" d="M1.5 3h5l1.5 1.5h6.5v9h-13z"/></svg>
+"##;
+
+const ICON_FOLDER_OPEN: &str = r##"<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><path fill="#90a4ae" d="M1.5 3h5l1.5 1.5h6v2h-10l-2 7h-.5z"/><path fill="#b0bec5" d="M4 7.5h11.5l-2 6H2z"/></svg>
+"##;
+
+const ICON_MARKDOWN: &str = r##"<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><rect x="1" y="3.5" width="14" height="9" rx="1.5" fill="#42a5f5"/><path fill="#fff" d="M3 10.5v-5h1.5L6 7.5l1.5-2H9v5H7.5V8L6 10 4.5 8v2.5zm8 0L9.5 8h1V5.5H12V8h1z"/></svg>
+"##;
+
+const LANGUAGE_MANIFEST: &str = r#"id = "__ID__"
+name = "__NAME__"
+version = "0.1.0"
+description = "Language support for .__SLUG__ files: detection, comments and indentation."
+authors = []
+engines.openidea = "^1.0"
+
+# Same format as languages/<id>.toml in the IDE repository.
+[[contributes.languages]]
+path = "languages/__SLUG__.toml"
+"#;
+
+const LANGUAGE_DEF: &str = r##"id = "__SLUG__"
+name = "__NAME__"
+extensions = ["__SLUG__"]
+line-comment = "#"
+indent = { tab-size = 2, insert-spaces = true }
+# Borrow an existing CodeMirror mode for instant highlighting.
+ui-mode = "Properties files"
+"##;

crates/ide-host/src/bin/server.rs

@@ -1,6 +1,8 @@
 //! `openidea-server --stdio`: the IDE backend for remote development, serving
 //! one desktop client over stdin / stdout (started by the client over SSH).
 
+use ide_host::plugins::remote::{RemotePluginLanguages, SYNC_COMMAND};
+use ide_host::plugins::remote_host::RemotePlugins;
 use ide_host::rpc::{self, Dispatcher};
 use ide_host::{Host, HostConfig};
 use ide_language::LanguageRegistry;
@@ -51,8 +53,12 @@ async fn run(base: PathBuf) -> i32 {
             return 1;
         }
     };
+    // The desktop's plugin languages (`plugin_sync_languages`); programs pinned on this machine.
+    let plugin_languages = RemotePluginLanguages::new(Some(&data_dir));
+    languages.attach_plugins(plugin_languages.store().clone());
     let peer = Arc::new(OnceLock::new());
     let sink_peer = peer.clone();
+    let plugins_data = data_dir.clone();
     let host = Arc::new(Host::new(HostConfig {
         config_dir,
         local_data_dir: data_dir.clone(),
@@ -64,8 +70,31 @@ async fn run(base: PathBuf) -> i32 {
         runtime: tokio::runtime::Handle::current(),
         project_environment: true,
     }));
+    // The desktop's code plugins run here, next to the project (`plugin_sync_packages`).
+    let plugins = match RemotePlugins::start(&plugins_data, &host, peer.clone()) {
+        Ok(p) => Some(p),
+        Err(e) => {
+            tracing::warn!("plugins are unavailable: {e}");
+            None
+        }
+    };
     tracing::info!("openidea-server {} ready", env!("CARGO_PKG_VERSION"));
-    rpc::serve(host.clone(), Dispatcher::standard(), peer, tokio::io::stdin(), tokio::io::stdout()).await;
+    let mut dispatcher = Dispatcher::standard();
+    if let Some(plugins) = &plugins {
+        plugins.register(&mut dispatcher);
+    }
+    dispatcher.add(SYNC_COMMAND, move |c| {
+        let remote = plugin_languages.clone();
+        async move {
+            let report = remote.sync(c.arg("languages")?);
+            c.host.plugin_languages_changed();
+            Ok(report)
+        }
+    });
+    rpc::serve(host.clone(), dispatcher, peer, tokio::io::stdin(), tokio::io::stdout()).await;
+    if let Some(plugins) = &plugins {
+        plugins.host().shutdown();
+    }
     // `process::exit` skips destructors: nothing started for the client may outlive it.
     if tokio::time::timeout(std::time::Duration::from_secs(10), host.shutdown()).await.is_err() {
         tracing::warn!("language servers did not shut down in time");

crates/ide-host/src/lib.rs

@@ -1,6 +1,6 @@
 //! The IDE backend without a UI toolkit: open projects per window, terminals,
 //! processes, settings and the remote services. The desktop shell (`src-tauri`)
-//! wraps one [`Host`] and adds windows, menus and plugins; `openidea-server`
+//! wraps one [`Host`] and adds windows and menus; `openidea-server`
 //! runs one on a remote machine and serves it over JSON-RPC ([`rpc`]).
 
 pub mod data_dirs;
@@ -10,6 +10,7 @@ mod java_runtime;
 mod kotlin_bridge;
 pub mod notebook;
 pub mod ops;
+pub mod plugins;
 mod project;
 mod proxy;
 mod requests;
@@ -133,6 +134,17 @@ impl Host {
         self.syntax.get_or_init(|| Arc::new(Syntax::new())).clone()
     }
 
+    /// Plugin languages or the servers they may start changed (they are part
+    /// of [`Self::languages`] and every project's fork): open documents are
+    /// detected again and language servers follow their new configuration.
+    pub fn plugin_languages_changed(&self) {
+        for project in self.projects() {
+            project.documents.redetect_languages();
+            let lsp = project.lsp.clone();
+            self.runtime.spawn(async move { lsp.reconfigure().await });
+        }
+    }
+
     /// Every open project (all windows).
     pub fn projects(&self) -> Vec<Arc<Project>> {
         self.projects.read().values().cloned().collect()

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

@@ -30,6 +30,17 @@ pub fn set_command(host: &Host, window: &str, id: String, command: Option<String
     host.project(window)?.agents.set_builtin_command(&id, command)
 }
 
+/// Environment variables built-in agent `id` starts with; empty clears them.
+pub fn set_env(
+    host: &Host,
+    window: &str,
+    id: String,
+    env: std::collections::BTreeMap<String, String>,
+) -> IdeResult<()> {
+    host.require_trust(window)?;
+    host.project(window)?.agents.set_builtin_env(&id, env)
+}
+
 /// Where ACP Registry agents are saved (`<config>/agents`, like the user's own) and installed.
 pub(crate) fn registry_paths(host: &Host) -> RegistryPaths {
     RegistryPaths::new(&host.config_dir, &host.local_data_dir)
@@ -195,6 +206,7 @@ pub(crate) fn register(d: &mut Dispatcher) {
     d.add("agent_subscribe", |c| async move { subscribe(&c.host, &c.window, c.channel("onEvent")?) });
     d.add("agent_providers", |c| async move { providers(&c.host, &c.window) });
     d.add("agent_set_command", |c| async move { set_command(&c.host, &c.window, c.arg("id")?, c.arg("command")?) });
+    d.add("agent_set_env", |c| async move { set_env(&c.host, &c.window, c.arg("id")?, c.arg("env")?) });
     d.add("agent_registry_list", |c| async move { registry_list(&c.host, &c.window, c.arg("request")?).await });
     d.add("agent_registry_install", |c| async move {
         registry_install(&c.host, &c.window, c.arg("id")?, c.arg("request")?, c.sender("onEvent")?).await

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

@@ -116,6 +116,11 @@ pub async fn build_sync(
             tracing::warn!("Maven profiles not saved: {e}");
             false
         });
+    if profiles_changed {
+        // The modules of the chosen profiles are read from the POMs with them from now on (the
+        // project tree's module folders too), whether or not Maven itself can run.
+        project.sink.emit(ide_core::IdeEvent::ProjectRootsChanged { root: project.root.clone().into() });
+    }
     let token = host.begin_project_request(window, request);
     let result = tokio::task::spawn_blocking(move || {
         let current = load(&root, &cache, &settings);
@@ -217,6 +222,22 @@ fn declaring_pom(
     )))
 }
 
+/// The `.toml` of a version catalog the build imports as `group:artifact:version`, once a
+/// build has downloaded it (`ide_sdk::libraries::published_version_catalog`).
+pub async fn gradle_published_catalog(
+    host: &Host,
+    window: &str,
+    coordinates: String,
+) -> IdeResult<Option<ide_core::IpcPath>> {
+    let project = host.project(window)?;
+    tokio::task::spawn_blocking(move || {
+        ide_sdk::libraries::published_version_catalog(&project.root, &project.settings.effective(), &coordinates)
+            .map(Into::into)
+    })
+    .await
+    .map_err(join_err)
+}
+
 /// Where the direct dependency `dependency` of the Maven module `pom` is declared.
 pub async fn maven_dependency_declaration(
     host: &Host,
@@ -296,7 +317,7 @@ pub async fn build_run(
                 let settings = ide_workspace::SettingsStore::load(&config_dir, Some(member)).effective();
                 let member_cache = cache.join(crate::project::project_key(member));
                 let model = with_profiles(load(member, &member_cache, &settings), &member_cache);
-                let plan = compile::plan(member, &model, kind, file.as_deref())?;
+                let plan = compile::plan(member, &model, kind, file.as_deref(), settings.cmake.profiles.as_deref())?;
                 match &mut combined {
                     Some(combined) => combined.steps.extend(plan.steps),
                     None => combined = Some(plan),
@@ -306,7 +327,13 @@ pub async fn build_run(
             plan.title = workspace.name;
             plan
         } else {
-            compile::plan(&root, &with_profiles(load(&root, &cache, &settings), &cache), kind, file.as_deref())?
+            compile::plan(
+                &root,
+                &with_profiles(load(&root, &cache, &settings), &cache),
+                kind,
+                file.as_deref(),
+                settings.cmake.profiles.as_deref(),
+            )?
         };
         let result = compile::run(&root, &plan, &token, &|e| {
             let _ = on_event.send(e);
@@ -337,6 +364,9 @@ pub(crate) fn register(d: &mut Dispatcher) {
         )
         .await
     });
+    d.add("gradle_published_catalog", |c| async move {
+        gradle_published_catalog(&c.host, &c.window, c.arg("coordinates")?).await
+    });
     d.add("maven_dependency_declaration", |c| async move {
         maven_dependency_declaration(&c.host, &c.window, c.arg("pom")?, c.arg("dependency")?).await
     });

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

@@ -188,6 +188,19 @@ pub async fn debug_stop(host: &Host, _window: &str, session: DebugSessionId) ->
     host.debugger.stop(session).await
 }
 
+/// The adapter's completions for an expression being typed in the frame `frame_id`.
+pub async fn debug_completions(
+    host: &Host,
+    _window: &str,
+    session: DebugSessionId,
+    frame_id: Option<i64>,
+    text: String,
+    line: u32,
+    column: u32,
+) -> IdeResult<Vec<ide_dap::DebugCompletion>> {
+    host.debugger.completions(session, frame_id, text, line, column).await
+}
+
 /// Evaluate with an explicit DAP context: `repl`, `watch`, `hover` or `clipboard`.
 pub async fn debug_evaluate_in(
     host: &Host,
@@ -376,6 +389,18 @@ pub(crate) fn register(d: &mut Dispatcher) {
         .await
     });
     d.add("debug_stop", |c| async move { debug_stop(&c.host, &c.window, c.arg("session")?).await });
+    d.add("debug_completions", |c| async move {
+        debug_completions(
+            &c.host,
+            &c.window,
+            c.arg("session")?,
+            c.arg("frameId")?,
+            c.arg("text")?,
+            c.arg("line")?,
+            c.arg("column")?,
+        )
+        .await
+    });
     d.add("debug_evaluate_in", |c| async move {
         debug_evaluate_in(
             &c.host,

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

@@ -0,0 +1,17 @@
+//! Docker run configurations: the environment their `docker` command line runs with.
+use crate::Host;
+use crate::rpc::Dispatcher;
+use ide_core::IdeResult;
+use ide_docker::DockerEndpoint;
+use std::collections::BTreeMap;
+
+/// The endpoint's variables plus a `PATH` that finds this host's `docker`. A remote project
+/// gets them from the server, since its run configurations start on the remote host.
+pub async fn run_env(host: &Host, endpoint: DockerEndpoint) -> IdeResult<BTreeMap<String, String>> {
+    endpoint.validate()?;
+    host.blocking(move || Ok(ide_docker::run_env(&endpoint))).await
+}
+
+pub(crate) fn register(d: &mut Dispatcher) {
+    d.add("docker_run_env", |c| async move { run_env(&c.host, c.arg("endpoint")?).await });
+}

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

@@ -1,9 +1,11 @@
 use super::doc::blocking;
 use crate::Host;
 use crate::apply_workspace_edit as apply_edit;
+use crate::plugins::{ProviderKind, editor_providers_for as editor_providers};
 use crate::rpc::Dispatcher;
 use ide_core::{DocId, IdeResult, Location, Pos, Range, RequestId, ServerId, TextEdit, WorkspaceEdit};
 use ide_lsp::types::*;
+use ide_plugin::ProviderDocument;
 
 async fn prepare_actions(
     project: std::sync::Arc<crate::Project>,
@@ -38,9 +40,99 @@ pub async fn lsp_completion(
 ) -> IdeResult<CompletionList> {
     let lsp = host.project(window)?.lsp.clone();
     let cancel = host.begin_request(request);
-    let result = lsp.completion(doc, pos, trigger, cancel).await;
+    let result = lsp.completion(doc, pos, trigger.clone(), cancel).await;
     host.end_request(request);
-    result
+    // Plugin providers (`[[contributes.providers]]`) add theirs.
+    let Some((plugins, d)) = plugin_providers(host, window, doc, ProviderKind::Completion) else { return result };
+    let items = plugin_call(move || plugins.provide_completion(&d, pos, trigger.as_deref())).await.unwrap_or_default();
+    if items.is_empty() {
+        return result;
+    }
+    let mut list = result.unwrap_or(CompletionList { is_incomplete: false, items: Vec::new() });
+    list.items.extend(items.into_iter().map(|(_, item)| plugin_completion(item)));
+    Ok(list)
+}
+
+/// The plugin host and the document, when some plugin provides `kind`.
+fn plugin_providers(
+    host: &Host,
+    window: &str,
+    doc: DocId,
+    kind: ProviderKind,
+) -> Option<(std::sync::Arc<crate::plugins::PluginHost>, ProviderDocument)> {
+    let plugins = editor_providers(kind)?;
+    let snap = host.project(window).ok()?.documents.snapshot(doc).ok()?;
+    let d = ProviderDocument {
+        path: snap.path.0,
+        language: snap.language.0,
+        version: u64::from(snap.version),
+        text: snap.text,
+    };
+    Some((plugins, d))
+}
+
+/// Plugin calls block (the plugin's actor thread does the work).
+async fn plugin_call<T: Send + 'static>(f: impl FnOnce() -> T + Send + 'static) -> Option<T> {
+    tokio::task::spawn_blocking(f).await.ok()
+}
+
+/// Items from plugins carry no server (resolve and commands don't apply).
+const PLUGIN_SERVER: ServerId = ServerId(0);
+
+/// A plugin's `completion-item.kind` (wit/providers.wit lists them).
+fn plugin_completion_kind(kind: &str) -> Option<CompletionKind> {
+    Some(match kind {
+        "text" => CompletionKind::Text,
+        "method" => CompletionKind::Method,
+        "function" => CompletionKind::Function,
+        "constructor" => CompletionKind::Constructor,
+        "field" => CompletionKind::Field,
+        "variable" => CompletionKind::Variable,
+        "class" => CompletionKind::Class,
+        "interface" => CompletionKind::Interface,
+        "module" => CompletionKind::Module,
+        "property" => CompletionKind::Property,
+        "unit" => CompletionKind::Unit,
+        "value" => CompletionKind::Value,
+        "enum" => CompletionKind::Enum,
+        "keyword" => CompletionKind::Keyword,
+        "snippet" => CompletionKind::Snippet,
+        "color" => CompletionKind::Color,
+        "file" => CompletionKind::File,
+        "reference" => CompletionKind::Reference,
+        "folder" => CompletionKind::Folder,
+        "enum-member" => CompletionKind::EnumMember,
+        "constant" => CompletionKind::Constant,
+        "struct" => CompletionKind::Struct,
+        "event" => CompletionKind::Event,
+        "operator" => CompletionKind::Operator,
+        "type-parameter" => CompletionKind::TypeParameter,
+        _ => return None,
+    })
+}
+
+fn plugin_completion(item: ide_plugin::CompletionItem) -> CompletionItem {
+    let kind = item.kind.as_deref().and_then(plugin_completion_kind);
+    CompletionItem {
+        label: item.label,
+        label_detail: None,
+        detail: item.detail,
+        kind,
+        documentation: item.documentation.map(|value| Markup { kind: "markdown".into(), value }),
+        sort_text: item.sort_text,
+        filter_text: None,
+        preselect: false,
+        deprecated: false,
+        insert_text: item.insert_text,
+        is_snippet: false,
+        replace_range: item.replace,
+        replace_range_tab: None,
+        additional_edits: Vec::new(),
+        commit_characters: Vec::new(),
+        command: None,
+        data: None,
+        server: PLUGIN_SERVER,
+    }
 }
 
 /// Inline (ghost text) suggestions at `pos`; `automatic` when triggered by typing.
@@ -54,9 +146,26 @@ pub async fn lsp_inline_completion(
 ) -> IdeResult<Vec<InlineCompletionItem>> {
     let lsp = host.project(window)?.lsp.clone();
     let cancel = host.begin_request(request);
-    let result = lsp.inline_completion(doc, pos, automatic, cancel).await;
+    let result = lsp.inline_completion(doc, pos, automatic, cancel.clone()).await;
+    // Plugins: cancelled (cooperatively) when the editor cancels the request.
+    let plugin = match plugin_providers(host, window, doc, ProviderKind::InlineCompletion) {
+        Some((plugins, d)) if !matches!(&result, Ok(items) if !items.is_empty()) => {
+            let cancel = cancel.clone();
+            plugin_call(move || plugins.provide_inline_completion(&d, pos, &cancel)).await.flatten()
+        }
+        _ => None,
+    };
     host.end_request(request);
-    result
+    match plugin {
+        Some((_, s)) => Ok(vec![InlineCompletionItem {
+            insert_text: s.insert_text,
+            range: s.replace,
+            filter_text: None,
+            command: None,
+            server: PLUGIN_SERVER,
+        }]),
+        None => result,
+    }
 }
 
 pub async fn lsp_resolve_completion(
@@ -87,7 +196,40 @@ pub async fn lsp_signature_help(host: &Host, window: &str, doc: DocId, pos: Pos)
 }
 
 pub async fn lsp_goto(host: &Host, window: &str, doc: DocId, pos: Pos, kind: GotoKind) -> IdeResult<Vec<Location>> {
-    host.project(window)?.lsp.goto(doc, pos, kind).await
+    let result = host.project(window)?.lsp.goto(doc, pos, kind).await;
+    if kind != GotoKind::Definition {
+        return result;
+    }
+    let Some((plugins, d)) = plugin_providers(host, window, doc, ProviderKind::Definition) else { return result };
+    let found = plugin_call(move || plugins.provide_definition(&d, pos)).await.unwrap_or_default();
+    if found.is_empty() {
+        return result;
+    }
+    let mut out = result.unwrap_or_default();
+    out.extend(found.into_iter().map(|l| Location { path: l.path.into(), range: l.range, uri: None }));
+    Ok(out)
+}
+
+/// Gutter markers from plugins (`line-markers` providers) for `doc`.
+pub async fn plugin_line_markers(
+    host: &Host,
+    window: &str,
+    doc: DocId,
+) -> IdeResult<Vec<crate::plugins::LineMarkerInfo>> {
+    let Some((plugins, d)) = plugin_providers(host, window, doc, ProviderKind::LineMarkers) else {
+        return Ok(Vec::new());
+    };
+    let markers = plugin_call(move || plugins.provide_line_markers(&d)).await.unwrap_or_default();
+    Ok(markers
+        .into_iter()
+        .map(|(plugin_id, m)| crate::plugins::LineMarkerInfo {
+            plugin_id,
+            line: m.line,
+            icon: m.icon,
+            tooltip: m.tooltip,
+            target: m.target.map(|l| Location { path: l.path.into(), range: l.range, uri: None }),
+        })
+        .collect())
 }
 
 /// Implementations of the symbols at `positions`, one list per position (the
@@ -165,10 +307,47 @@ pub async fn lsp_code_actions(
     let project = host.project(window)?;
     let documents = project.documents.clone();
     let version = blocking(move || documents.version(doc)).await?;
-    let actions = project.lsp.code_actions(doc, range, only).await?;
+    let result = project.lsp.code_actions(doc, range, only.clone()).await;
+    let plugin_actions = match plugin_providers(host, window, doc, ProviderKind::CodeActions) {
+        Some((plugins, d)) => plugin_call(move || plugins.provide_code_actions(&d, range)).await.unwrap_or_default(),
+        None => Vec::new(),
+    };
+    let plugin_actions: Vec<CodeAction> = plugin_actions
+        .into_iter()
+        .map(|(_, a)| plugin_code_action(a))
+        .filter(|a| {
+            only.is_empty()
+                || a.kind.as_ref().is_some_and(|k| only.iter().any(|o| k == o || k.starts_with(&format!("{o}."))))
+        })
+        .collect();
+    let actions = if plugin_actions.is_empty() {
+        result?
+    } else {
+        let mut out = result.unwrap_or_default();
+        out.extend(plugin_actions);
+        out
+    };
     prepare_actions(project, doc, version, actions).await
 }
 
+fn plugin_code_action(a: ide_plugin::CodeAction) -> CodeAction {
+    let files = a
+        .edits
+        .into_iter()
+        .map(|(path, edits)| ide_core::FileEdit::Edit { path: path.into(), edits, version: None })
+        .collect();
+    CodeAction {
+        title: a.title,
+        kind: a.kind,
+        is_preferred: a.preferred,
+        disabled_reason: None,
+        edit: Some(WorkspaceEdit { files, preconditions: Vec::new() }),
+        command: None,
+        data: None,
+        server: PLUGIN_SERVER,
+    }
+}
+
 /// Cancellable code actions with the kinds the servers advertise (Refactor This, refactoring availability).
 pub async fn lsp_code_action_query(
     host: &Host,
@@ -551,3 +730,28 @@ pub(crate) fn register(d: &mut Dispatcher) {
         lsp_execute_command(&c.host, &c.window, c.arg("doc")?, c.arg("command")?).await
     });
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn every_completion_kind_the_plugin_api_documents_is_understood() {
+        let wit = include_str!("../../../../wit/providers.wit");
+        let doc: String = wit
+            .lines()
+            .map(|l| l.trim().trim_start_matches("///").trim())
+            .skip_while(|l| !l.starts_with("Icon and sort group:"))
+            .take_while(|l| !l.starts_with("kind:"))
+            .collect::<Vec<_>>()
+            .join(" ");
+        let list = doc.strip_prefix("Icon and sort group:").unwrap().split(". Unknown").next().unwrap();
+        let list = list.replace(" or ", ", ");
+        let kinds: Vec<&str> = list.split(',').map(str::trim).filter(|k| !k.is_empty()).collect();
+        assert_eq!(kinds.len(), 25, "{kinds:?}");
+        for k in kinds {
+            assert!(plugin_completion_kind(k).is_some(), "{k:?}");
+        }
+        assert_eq!(plugin_completion_kind("nonsense"), None);
+    }
+}

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

@@ -12,6 +12,7 @@ pub mod debug;
 pub mod dependencies;
 pub mod deploy;
 pub mod doc;
+pub mod docker;
 pub mod env;
 pub mod fs;
 pub mod history;
@@ -87,6 +88,7 @@ pub fn register_all(d: &mut crate::rpc::Dispatcher) {
     run::register(d);
     env::register(d);
     deploy::register(d);
+    docker::register(d);
     db::register(d);
 }
 

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

@@ -82,6 +82,58 @@ pub fn save_configs(
     ide_run::save_user_configs_with_removals(&project.root, &configs, removed_detected_ids)
 }
 
+/// The project `config` runs in (a workspace member, by its working directory) and its settings.
+fn settings_for(
+    host: &Host,
+    project: &crate::project::Project,
+    config: &RunConfig,
+) -> IdeResult<(std::path::PathBuf, ide_core::settings::Settings)> {
+    let member = ide_workspace::workspace::Workspace::load(&project.root)?.and_then(|workspace| {
+        let cwd = config.cwd.as_deref()?;
+        workspace.projects.into_iter().filter(|root| cwd.starts_with(root)).max_by_key(|root| root.components().count())
+    });
+    Ok(match member {
+        Some(root) => {
+            let settings = ide_workspace::SettingsStore::load(&host.config_dir, Some(&root)).effective();
+            (root, settings)
+        }
+        None => (project.root.clone(), project.settings.effective()),
+    })
+}
+
+/// Temporary configurations as they are kept between sessions: without what settings derived
+/// (toolchain commands, Maven options, `JAVA_HOME`…), so they follow later settings changes.
+pub fn without_derived(host: &Host, window: &str, configs: Vec<RunConfig>) -> IdeResult<Vec<RunConfig>> {
+    host.require_trust(window)?;
+    let project = host.project(window)?;
+    configs
+        .into_iter()
+        .map(|c| {
+            if c.kind == "gradle" {
+                return Ok(c);
+            }
+            let (root, settings) = settings_for(host, &project, &c)?;
+            Ok(ide_sdk::apply::without_derived(&c, &root, &settings))
+        })
+        .collect()
+}
+
+/// Kept temporary configurations with today's settings applied, as [`configs`] lists the others.
+pub fn apply_settings(host: &Host, window: &str, configs: Vec<RunConfig>) -> IdeResult<Vec<RunConfig>> {
+    host.require_trust(window)?;
+    let project = host.project(window)?;
+    configs
+        .into_iter()
+        .map(|mut c| {
+            if c.kind != "gradle" {
+                let (root, settings) = settings_for(host, &project, &c)?;
+                ide_sdk::apply::apply_to_run_configs(std::slice::from_mut(&mut c), &root, &settings);
+            }
+            Ok(c)
+        })
+        .collect()
+}
+
 pub async fn start(host: &Host, window: &str, config: RunConfig, on_output: Emit<OutputChunk>) -> IdeResult<RunInfo> {
     host.require_trust(window)?;
     let project = host.project(window)?;
@@ -100,15 +152,8 @@ pub async fn start(host: &Host, window: &str, config: RunConfig, on_output: Emit
             .run(&settings, &project.root, &config, project.sink.clone(), Box::new(move |c| out(c)))
             .await;
     }
-    let member = ide_workspace::workspace::Workspace::load(&project.root)?.and_then(|workspace| {
-        let cwd = config.cwd.as_deref()?;
-        workspace.projects.into_iter().filter(|root| cwd.starts_with(root)).max_by_key(|root| root.components().count())
-    });
-    let root = member.as_ref().unwrap_or(&project.root);
-    let settings = match &member {
-        Some(root) => ide_workspace::SettingsStore::load(&host.config_dir, Some(root)).effective(),
-        None => project.settings.effective(),
-    };
+    let (root, settings) = settings_for(host, &project, &config)?;
+    let root = &root;
     // Configurations made in the UI name bare tools (`godot`) that may live outside PATH.
     let mut config = config;
     if matches!(config.kind.as_str(), "gradle" | "tomcat") {
@@ -147,7 +192,7 @@ pub async fn start(host: &Host, window: &str, config: RunConfig, on_output: Emit
     let encoding = settings.console.encoding;
     let options = StartOptions {
         encoding: Some(encoding).filter(|e| !e.trim().is_empty()),
-        python_paths: if member.is_some() { vec![root.clone()] } else { super::python::paths(&project) },
+        python_paths: if *root != project.root { vec![root.clone()] } else { super::python::paths(&project) },
     };
     project.require_trust()?;
     let mut sink = project.sink.clone();

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

@@ -241,6 +241,35 @@ pub async fn run_tomcat_update(host: &Host, window: &str, config: RunConfig, mod
         .map_err(|e| IdeError::internal(e.to_string()))?
 }
 
+/// Updates a running Tomcat artifact deployment from the module's compiled output and web
+/// resources (`ide_run::tomcat::sync_outputs`). `false`: rebuild the WAR instead.
+pub async fn run_tomcat_sync(
+    host: &Host,
+    window: &str,
+    config: RunConfig,
+    module: std::path::PathBuf,
+    class_paths: Vec<String>,
+    resources_only: bool,
+) -> IdeResult<bool> {
+    host.require_trust(window)?;
+    let project = host.project(window)?;
+    if !host.processes.list().iter().any(|r| r.running && r.config_id == config.id) {
+        return Err(IdeError::invalid("Start this Tomcat configuration before updating it"));
+    }
+    if config.extras.params.get("deployment").is_some_and(|v| v != "artifact") {
+        return Ok(false);
+    }
+    tokio::task::spawn_blocking(move || {
+        let module = dunce::canonicalize(project.root.join(module))?;
+        let class_paths: Vec<_> =
+            class_paths.iter().filter_map(|p| dunce::canonicalize(project.root.join(p)).ok()).collect();
+        let base = ide_run::tomcat::base_dir(&project.cache_dir, &config.id);
+        ide_run::tomcat::sync_outputs(&base, &module, &class_paths, resources_only)
+    })
+    .await
+    .map_err(|e| IdeError::internal(e.to_string()))?
+}
+
 /// Commands of this module the remote server answers.
 pub(crate) fn register(d: &mut Dispatcher) {
     d.add("run_dotnet_resolve", |c| async move {
@@ -255,6 +284,17 @@ pub(crate) fn register(d: &mut Dispatcher) {
     d.add("run_tomcat_home", |c| async move { run_tomcat_home(&c.host, &c.window, c.arg("home")?).await });
     d.add("run_tomcat_artifacts", |c| async move { run_tomcat_artifacts(&c.host, &c.window).await });
     d.add("run_tomcat_build", |c| async move { run_tomcat_build(&c.host, &c.window, c.arg("config")?).await });
+    d.add("run_tomcat_sync", |c| async move {
+        run_tomcat_sync(
+            &c.host,
+            &c.window,
+            c.arg("config")?,
+            c.arg("module")?,
+            c.arg("classPaths")?,
+            c.arg("resourcesOnly")?,
+        )
+        .await
+    });
     d.add("run_tomcat_update", |c| async move {
         run_tomcat_update(&c.host, &c.window, c.arg("config")?, c.arg("mode")?).await
     });

crates/ide-host/src/plugins/api.rs

@@ -0,0 +1,803 @@
+//! [`HostApi`] for one plugin's code: what its imports reach in the IDE.
+//! Capabilities were checked by the runtime before any of this runs.
+
+use super::{PluginEvent, PluginEventSink};
+use ide_core::{CancellationToken, TextEdit};
+use ide_extension::Package;
+use ide_language::ProgramPin;
+use ide_plugin::{
+    EventKind, HostApi, HostError, HttpRequest, HttpResponse, NotificationLevel, ProcessOutput, RepositoryStatus,
+    StatusItem,
+};
+use parking_lot::{Mutex, RwLock};
+use std::collections::{BTreeMap, BTreeSet, HashMap};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::time::{Duration, Instant};
+
+/// Largest storage of one plugin (keys + values).
+const MAX_STORAGE: usize = 1 << 20;
+const MAX_KEY: usize = 256;
+/// Most status bar items per plugin.
+const MAX_STATUS_ITEMS: usize = 8;
+
+/// What plugins see of the open projects; provided by the app
+/// ([`super::PluginHost::set_workspace`]), over [`crate::Host`] on the desktop.
+pub trait PluginWorkspace: Send + Sync {
+    /// Roots of the open projects.
+    fn projects(&self) -> Vec<PathBuf>;
+    /// Unsaved text of the open document at `path`.
+    fn buffer_text(&self, path: &Path) -> Option<String>;
+    /// Version and text of the open document at `path`.
+    fn document(&self, path: &Path) -> Option<(u64, String)>;
+    /// Applies `edits` to the open document at `path` if it is still at
+    /// `version`, as one change (one undo step in the editor).
+    fn apply_edits(&self, path: &Path, version: u64, edits: &[TextEdit]) -> Result<u64, HostError>;
+    /// Code from the project may run (git hooks and config on fetch).
+    fn trusted(&self, root: &Path) -> bool;
+    /// Root of the project open in `window`.
+    fn project_of(&self, window: &str) -> Option<PathBuf>;
+    /// Shows `items` as producer `source`'s diagnostics of `path` (replacing earlier ones).
+    fn publish_diagnostics(&self, source: &str, path: &Path, items: Vec<ide_core::Diagnostic>)
+    -> Result<(), HostError>;
+    /// The user's values of `plugin`'s settings: the project's at `root`
+    /// (over global), or global.
+    fn plugin_settings(&self, _plugin: &str, _root: Option<&Path>) -> serde_json::Map<String, serde_json::Value> {
+        serde_json::Map::new()
+    }
+}
+
+/// Where plugin secrets live (the OS keychain on the desktop). Plugins can
+/// only ask whether one is set; values go out only inside `net` requests.
+pub trait SecretStore: Send + Sync {
+    fn get(&self, plugin: &str, name: &str) -> Option<String>;
+    /// Sets, or (`None`) deletes.
+    fn set(&self, plugin: &str, name: &str, value: Option<&str>) -> Result<(), String>;
+}
+
+/// Fallback [`SecretStore`]: one file per plugin, readable only by the user.
+pub struct FileSecretStore {
+    pub dir: PathBuf,
+}
+
+impl FileSecretStore {
+    fn file(&self, plugin: &str) -> PathBuf {
+        self.dir.join(plugin).join("secrets.json")
+    }
+
+    fn load(&self, plugin: &str) -> BTreeMap<String, String> {
+        std::fs::read(self.file(plugin)).ok().and_then(|b| serde_json::from_slice(&b).ok()).unwrap_or_default()
+    }
+}
+
+impl SecretStore for FileSecretStore {
+    fn get(&self, plugin: &str, name: &str) -> Option<String> {
+        self.load(plugin).remove(name)
+    }
+
+    fn set(&self, plugin: &str, name: &str, value: Option<&str>) -> Result<(), String> {
+        let mut map = self.load(plugin);
+        match value {
+            Some(v) => map.insert(name.to_owned(), v.to_owned()),
+            None => map.remove(name),
+        };
+        let file = self.file(plugin);
+        std::fs::create_dir_all(file.parent().expect("has parent")).map_err(|e| e.to_string())?;
+        let bytes = serde_json::to_vec(&map).map_err(|e| e.to_string())?;
+        let tmp = file.with_extension("tmp");
+        std::fs::write(&tmp, bytes).map_err(|e| e.to_string())?;
+        #[cfg(unix)]
+        {
+            use std::os::unix::fs::PermissionsExt;
+            let _ = std::fs::set_permissions(&tmp, std::fs::Permissions::from_mode(0o600));
+        }
+        std::fs::rename(&tmp, &file).map_err(|e| e.to_string())
+    }
+}
+
+/// Largest response body a plugin receives.
+const MAX_RESPONSE: usize = 8 << 20;
+/// Largest stdout / stderr kept from a process.
+const MAX_OUTPUT: usize = 4 << 20;
+/// Most files `find-files` walks before giving up.
+const MAX_WALK: usize = 200_000;
+
+/// Runtime for plugin HTTP requests (actor threads block on it).
+pub(super) fn net_runtime() -> &'static tokio::runtime::Runtime {
+    static RT: std::sync::OnceLock<tokio::runtime::Runtime> = std::sync::OnceLock::new();
+    RT.get_or_init(|| {
+        tokio::runtime::Builder::new_multi_thread()
+            .worker_threads(2)
+            .thread_name("plugin-net")
+            .enable_all()
+            .build()
+            .expect("plugin network runtime")
+    })
+}
+
+/// Replaces `{{secret:<name>}}` in `value` with the plugin's secrets.
+fn fill_secrets(value: &str, lookup: impl Fn(&str) -> Option<String>) -> Result<String, HostError> {
+    let mut out = String::with_capacity(value.len());
+    let mut rest = value;
+    while let Some(i) = rest.find("{{secret:") {
+        out.push_str(&rest[..i]);
+        let after = &rest[i + "{{secret:".len()..];
+        let end = after.find("}}").ok_or_else(|| HostError::Invalid("unterminated {{secret:…}}".into()))?;
+        let name = &after[..end];
+        let secret = lookup(name).ok_or_else(|| HostError::NotFound(format!("secret {name:?} is not set")))?;
+        out.push_str(&secret);
+        rest = &after[end + 2..];
+    }
+    out.push_str(rest);
+    Ok(out)
+}
+
+/// A plugin task shown in the UI.
+struct TaskEntry {
+    plugin: String,
+    cancel: CancellationToken,
+    cancelled: bool,
+}
+
+/// State shared by the host and every plugin's [`PluginApi`].
+pub(super) struct Shared {
+    pub sink: Arc<dyn PluginEventSink>,
+    pub workspace: RwLock<Option<Arc<dyn PluginWorkspace>>>,
+    /// `<plugins>/.data`: one directory per plugin id.
+    pub data_dir: PathBuf,
+    tasks: Mutex<HashMap<u64, TaskEntry>>,
+    next_task: AtomicU64,
+    /// (plugin, item id) → item, for windows opened later.
+    status: Mutex<BTreeMap<(String, String), StatusItem>>,
+    /// plugin → kinds subscribed at run time (kept across idle reclaim).
+    pub subscriptions: Mutex<HashMap<String, BTreeSet<EventKind>>>,
+    /// plugin → files it shows problems for, withdrawn when it stops.
+    diagnostics: Mutex<HashMap<String, BTreeSet<PathBuf>>>,
+    pub secrets: RwLock<Arc<dyn SecretStore>>,
+    /// (plugin, `process:` capability) → the approved program.
+    pub pins: Arc<RwLock<HashMap<(String, String), ProgramPin>>>,
+    /// Validated UI declarations (settings schemas, declared views).
+    pub ui: Arc<ide_extension::UiStore>,
+}
+
+impl Shared {
+    pub fn new(
+        sink: Arc<dyn PluginEventSink>,
+        data_dir: PathBuf,
+        pins: Arc<RwLock<HashMap<(String, String), ProgramPin>>>,
+        ui: Arc<ide_extension::UiStore>,
+    ) -> Arc<Self> {
+        Arc::new(Self {
+            ui,
+            sink,
+            workspace: RwLock::new(None),
+            secrets: RwLock::new(Arc::new(FileSecretStore { dir: data_dir.clone() })),
+            pins,
+            data_dir,
+            tasks: Mutex::default(),
+            next_task: AtomicU64::new(1),
+            status: Mutex::default(),
+            subscriptions: Mutex::default(),
+            diagnostics: Mutex::default(),
+        })
+    }
+
+    fn workspace(&self) -> Option<Arc<dyn PluginWorkspace>> {
+        self.workspace.read().clone()
+    }
+
+    pub fn project_of(&self, window: &str) -> Option<PathBuf> {
+        self.workspace()?.project_of(window)
+    }
+
+    /// Shows `plugin`'s problems of `path`, remembering the file until they are
+    /// cleared (by the plugin, or when it stops).
+    fn publish_diagnostics(
+        &self,
+        plugin: &str,
+        path: &Path,
+        items: Vec<ide_core::Diagnostic>,
+    ) -> Result<(), HostError> {
+        let workspace = self.workspace().ok_or_else(|| HostError::NotFound("no project is open".into()))?;
+        let empty = items.is_empty();
+        workspace.publish_diagnostics(plugin, path, items)?;
+        let mut published = self.diagnostics.lock();
+        if empty {
+            if let Some(paths) = published.get_mut(plugin) {
+                paths.remove(path);
+                if paths.is_empty() {
+                    published.remove(plugin);
+                }
+            }
+        } else {
+            published.entry(plugin.to_owned()).or_default().insert(path.to_path_buf());
+        }
+        Ok(())
+    }
+
+    pub fn status_items(&self) -> Vec<(String, String, StatusItem)> {
+        self.status.lock().iter().map(|((p, id), item)| (p.clone(), id.clone(), item.clone())).collect()
+    }
+
+    /// Withdraws a plugin's run-time state (it stopped or failed). Its
+    /// subscriptions go only with `subscriptions`, as they survive restarts.
+    pub fn clear_plugin(&self, plugin: &str, subscriptions: bool) {
+        let removed: Vec<String> = {
+            let mut status = self.status.lock();
+            let ids: Vec<String> = status.keys().filter(|(p, _)| p == plugin).map(|(_, id)| id.clone()).collect();
+            for id in &ids {
+                status.remove(&(plugin.to_owned(), id.clone()));
+            }
+            ids
+        };
+        for id in removed {
+            self.sink.emit(None, PluginEvent::StatusItemChanged { plugin_id: plugin.to_owned(), id, item: None });
+        }
+        let tasks: Vec<u64> = self.tasks.lock().iter().filter(|(_, t)| t.plugin == plugin).map(|(id, _)| *id).collect();
+        for id in tasks {
+            self.end_task(id);
+        }
+        // Its problems go with it (an idle reclaim keeps them: it isn't cleared then).
+        let paths = self.diagnostics.lock().remove(plugin).unwrap_or_default();
+        if let Some(workspace) = self.workspace() {
+            for path in paths {
+                let _ = workspace.publish_diagnostics(plugin, &path, Vec::new());
+            }
+        }
+        if subscriptions && self.subscriptions.lock().remove(plugin).is_some() {
+            self.sink.emit(None, PluginEvent::SubscriptionsChanged);
+        }
+    }
+
+    /// The user cancelled a task in the UI.
+    pub fn cancel_task(&self, id: u64) -> bool {
+        let mut tasks = self.tasks.lock();
+        let Some(t) = tasks.get_mut(&id) else { return false };
+        t.cancelled = true;
+        t.cancel.cancel();
+        true
+    }
+
+    fn end_task(&self, id: u64) {
+        if let Some(t) = self.tasks.lock().remove(&id) {
+            self.sink.emit(None, PluginEvent::TaskEnded { plugin_id: t.plugin, task_id: id.to_string() });
+        }
+    }
+
+    pub fn storage_file(&self, plugin: &str) -> PathBuf {
+        self.data_dir.join(plugin).join("storage.json")
+    }
+}
+
+pub(super) struct PluginApi {
+    pub pkg: Package,
+    pub shared: Arc<Shared>,
+}
+
+impl PluginApi {
+    fn id(&self) -> &str {
+        self.pkg.id()
+    }
+
+    fn load_storage(&self) -> Result<BTreeMap<String, String>, HostError> {
+        match std::fs::read(self.shared.storage_file(self.id())) {
+            Ok(bytes) => serde_json::from_slice(&bytes).map_err(|e| HostError::Failed(format!("storage: {e}"))),
+            Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(BTreeMap::new()),
+            Err(e) => Err(HostError::Failed(format!("storage: {e}"))),
+        }
+    }
+
+    fn save_storage(&self, map: &BTreeMap<String, String>) -> Result<(), HostError> {
+        let file = self.shared.storage_file(self.id());
+        let bytes = serde_json::to_vec(map).map_err(|e| HostError::Failed(e.to_string()))?;
+        let io = |e: std::io::Error| HostError::Failed(format!("storage: {e}"));
+        std::fs::create_dir_all(file.parent().expect("has parent")).map_err(io)?;
+        let tmp = file.with_extension("tmp");
+        std::fs::write(&tmp, bytes).and_then(|()| std::fs::rename(&tmp, &file)).map_err(io)
+    }
+
+    /// The program approved for the (already checked) `process:` grant,
+    /// verified right before it starts.
+    fn approved_program(&self, program: &str) -> Result<PathBuf, HostError> {
+        let cap = format!("process:{program}");
+        // Granted without a pinned file: the program wasn't found when it was
+        // allowed, and installing it later approves nothing by itself.
+        let pin = self.shared.pins.read().get(&(self.id().to_owned(), cap.clone())).cloned().ok_or_else(|| {
+            HostError::Failed(format!(
+                "{cap}: `{program}` was not found when this permission was allowed; \
+                 install it, then allow {cap} again in Settings › Plugins"
+            ))
+        })?;
+        pin.verify().map(Path::to_path_buf).map_err(|e| HostError::Denied(format!("{cap}: {e}")))
+    }
+}
+
+fn failed(e: impl std::fmt::Display) -> HostError {
+    HostError::Failed(e.to_string())
+}
+
+impl HostApi for PluginApi {
+    fn notify(&self, client: Option<&str>, level: NotificationLevel, title: String, body: String) {
+        self.shared
+            .sink
+            .emit(client, PluginEvent::Notification { plugin_id: self.id().to_owned(), level, title, body });
+    }
+
+    fn status_item(&self, id: &str, item: Option<StatusItem>) {
+        let key = (self.id().to_owned(), id.to_owned());
+        {
+            let mut status = self.shared.status.lock();
+            match &item {
+                Some(item) => {
+                    let count = status.keys().filter(|(p, _)| p == self.id()).count();
+                    if !status.contains_key(&key) && count >= MAX_STATUS_ITEMS {
+                        tracing::warn!(plugin = %self.id(), "more than {MAX_STATUS_ITEMS} status items; {id:?} ignored");
+                        return;
+                    }
+                    if status.get(&key) == Some(item) {
+                        return;
+                    }
+                    status.insert(key, item.clone());
+                }
+                None => {
+                    if status.remove(&key).is_none() {
+                        return;
+                    }
+                }
+            }
+        }
+        self.shared
+            .sink
+            .emit(None, PluginEvent::StatusItemChanged { plugin_id: self.id().to_owned(), id: id.to_owned(), item });
+    }
+
+    fn projects(&self) -> Vec<PathBuf> {
+        self.shared.workspace().map(|w| w.projects()).unwrap_or_default()
+    }
+
+    fn buffer_text(&self, path: &Path) -> Option<String> {
+        self.shared.workspace()?.buffer_text(path)
+    }
+
+    fn document(&self, path: &Path) -> Option<(u64, String)> {
+        self.shared.workspace()?.document(path)
+    }
+
+    fn apply_edits(
+        &self,
+        _client: Option<&str>,
+        path: &Path,
+        version: u64,
+        edits: Vec<TextEdit>,
+    ) -> Result<u64, HostError> {
+        let workspace = self.shared.workspace().ok_or_else(|| HostError::NotFound("no project is open".into()))?;
+        workspace.apply_edits(path, version, &edits)
+    }
+
+    fn storage_get(&self, key: &str) -> Result<Option<String>, HostError> {
+        Ok(self.load_storage()?.get(key).cloned())
+    }
+
+    fn storage_set(&self, key: &str, value: Option<String>) -> Result<(), HostError> {
+        if key.is_empty() || key.len() > MAX_KEY {
+            return Err(HostError::Invalid(format!("keys are 1–{MAX_KEY} bytes")));
+        }
+        let mut map = self.load_storage()?;
+        let changed = match value {
+            Some(v) => map.insert(key.to_owned(), v.clone()).as_ref() != Some(&v),
+            None => map.remove(key).is_some(),
+        };
+        if !changed {
+            return Ok(());
+        }
+        let size: usize = map.iter().map(|(k, v)| k.len() + v.len()).sum();
+        if size > MAX_STORAGE {
+            return Err(HostError::Invalid(format!("storage is limited to {} KiB", MAX_STORAGE >> 10)));
+        }
+        self.save_storage(&map)
+    }
+
+    fn storage_keys(&self, prefix: &str) -> Result<Vec<String>, HostError> {
+        Ok(self.load_storage()?.into_keys().filter(|k| k.starts_with(prefix)).collect())
+    }
+
+    fn vcs_status(&self, root: &Path) -> Result<Option<RepositoryStatus>, HostError> {
+        let Some(repo) = ide_vcs::Repo::discover(root).map_err(failed)? else { return Ok(None) };
+        let info = repo.branch_info().map_err(failed)?;
+        let changed = repo.status().map_err(failed)?.len();
+        Ok(Some(RepositoryStatus {
+            root: repo.root().to_string_lossy().into_owned(),
+            branch: info.head,
+            commit: info.head_commit,
+            upstream: info.upstream,
+            ahead: info.ahead,
+            behind: info.behind,
+            operation: info.operation,
+            changed_files: u32::try_from(changed).unwrap_or(u32::MAX),
+        }))
+    }
+
+    fn vcs_fetch(&self, root: &Path, cancel: &CancellationToken) -> Result<(), HostError> {
+        let workspace = self.shared.workspace();
+        if !workspace.is_some_and(|w| w.trusted(root)) {
+            return Err(HostError::Failed("the project is in Restricted Mode: git does not run there".into()));
+        }
+        let Some(repo) = ide_vcs::Repo::discover(root).map_err(failed)? else {
+            return Err(HostError::NotFound("the project is not in a git repository".into()));
+        };
+        match repo.fetch(cancel, &|_| {}) {
+            Ok(()) => Ok(()),
+            Err(_) if cancel.is_cancelled() => Err(HostError::Cancelled),
+            Err(e) => Err(failed(e.message)),
+        }
+    }
+
+    fn find_files(&self, root: &Path, glob: &str, limit: usize) -> Result<Vec<String>, HostError> {
+        let matcher = globset::GlobBuilder::new(glob)
+            .literal_separator(true)
+            .build()
+            .map_err(|e| HostError::Invalid(format!("{glob:?}: {e}")))?
+            .compile_matcher();
+        let mut out = Vec::new();
+        for (n, entry) in ignore::WalkBuilder::new(root).hidden(true).build().flatten().enumerate() {
+            if n >= MAX_WALK || out.len() >= limit {
+                break;
+            }
+            if !entry.file_type().is_some_and(|t| t.is_file()) {
+                continue;
+            }
+            let Ok(rel) = entry.path().strip_prefix(root) else { continue };
+            if matcher.is_match(rel) {
+                out.push(entry.path().to_string_lossy().into_owned());
+            }
+        }
+        out.sort();
+        Ok(out)
+    }
+
+    fn publish_diagnostics(&self, path: &Path, items: Vec<ide_core::Diagnostic>) -> Result<(), HostError> {
+        self.shared.publish_diagnostics(self.id(), path, items)
+    }
+
+    fn fetch(&self, request: HttpRequest, cancel: &CancellationToken) -> Result<HttpResponse, HostError> {
+        let secrets = self.shared.secrets.read().clone();
+        let id = self.id().to_owned();
+        let mut headers = reqwest::header::HeaderMap::new();
+        for (name, value) in &request.headers {
+            let value = fill_secrets(value, |n| secrets.get(&id, n))?;
+            let name = reqwest::header::HeaderName::from_bytes(name.as_bytes())
+                .map_err(|e| HostError::Invalid(format!("header {name:?}: {e}")))?;
+            let mut value = reqwest::header::HeaderValue::from_str(&value)
+                .map_err(|e| HostError::Invalid(format!("header {name}: {e}")))?;
+            value.set_sensitive(true);
+            headers.append(name, value);
+        }
+        let method = reqwest::Method::from_bytes(request.method.to_ascii_uppercase().as_bytes())
+            .map_err(|_| HostError::Invalid(format!("method {:?}", request.method)))?;
+        let client = ide_http::client::shared().map_err(|e| HostError::Failed(e.message))?;
+        // A redirect to another host is refused after the fact (the shared
+        // client follows redirects).
+        let builder = client.request(method, &request.url).headers(headers).timeout(request.timeout);
+        let builder = match request.body {
+            Some(body) => builder.body(body),
+            None => builder,
+        };
+        let cancel = cancel.clone();
+        let host = ide_plugin::net_host(&request.url).map_err(HostError::Invalid)?;
+        net_runtime().block_on(async move {
+            let send = async {
+                let response = builder.send().await.map_err(|e| HostError::Failed(e.to_string()))?;
+                if ide_plugin::net_host(response.url().as_str()).ok().as_deref() != Some(host.as_str()) {
+                    return Err(HostError::Denied(format!(
+                        "net:{} (redirected)",
+                        response.url().host_str().unwrap_or("?")
+                    )));
+                }
+                let status = response.status().as_u16();
+                let headers = response
+                    .headers()
+                    .iter()
+                    .map(|(k, v)| (k.as_str().to_owned(), String::from_utf8_lossy(v.as_bytes()).into_owned()))
+                    .collect();
+                let mut body = Vec::new();
+                let mut response = response;
+                while let Some(chunk) = response.chunk().await.map_err(|e| HostError::Failed(e.to_string()))? {
+                    if body.len() + chunk.len() > MAX_RESPONSE {
+                        return Err(HostError::Failed("response larger than 8 MiB".into()));
+                    }
+                    body.extend_from_slice(&chunk);
+                }
+                Ok(HttpResponse { status, headers, body })
+            };
+            tokio::select! {
+                r = send => r,
+                () = cancel.cancelled() => Err(HostError::Cancelled),
+            }
+        })
+    }
+
+    fn secret_is_set(&self, name: &str) -> bool {
+        self.shared.secrets.read().get(self.id(), name).is_some()
+    }
+
+    fn run_process(
+        &self,
+        program: &str,
+        args: Vec<String>,
+        cwd: Option<&Path>,
+        stdin: Option<String>,
+        cancel: &CancellationToken,
+        timeout: Duration,
+    ) -> Result<ProcessOutput, HostError> {
+        let binary = self.approved_program(program)?;
+        let cwd = cwd.map(Path::to_path_buf).unwrap_or_else(|| self.shared.data_dir.join(self.id()));
+        let _ = std::fs::create_dir_all(&cwd);
+        let mut child = std::process::Command::new(&binary)
+            .args(&args)
+            .current_dir(&cwd)
+            .stdin(if stdin.is_some() { std::process::Stdio::piped() } else { std::process::Stdio::null() })
+            .stdout(std::process::Stdio::piped())
+            .stderr(std::process::Stdio::piped())
+            .spawn()
+            .map_err(|e| HostError::Failed(format!("{}: {e}", binary.display())))?;
+        if let (Some(input), Some(mut pipe)) = (stdin, child.stdin.take()) {
+            std::thread::spawn(move || {
+                use std::io::Write;
+                let _ = pipe.write_all(input.as_bytes());
+            });
+        }
+        let read = |pipe: Option<Box<dyn std::io::Read + Send>>| {
+            std::thread::spawn(move || {
+                use std::io::Read;
+                let mut out = Vec::new();
+                if let Some(p) = pipe {
+                    let _ = p.take(MAX_OUTPUT as u64).read_to_end(&mut out);
+                }
+                String::from_utf8_lossy(&out).into_owned()
+            })
+        };
+        let stdout = read(child.stdout.take().map(|p| Box::new(p) as Box<dyn std::io::Read + Send>));
+        let stderr = read(child.stderr.take().map(|p| Box::new(p) as Box<dyn std::io::Read + Send>));
+        let deadline = Instant::now() + timeout;
+        let status = loop {
+            if let Some(status) = child.try_wait().map_err(|e| HostError::Failed(e.to_string()))? {
+                break status;
+            }
+            if cancel.is_cancelled() || Instant::now() >= deadline {
+                let _ = child.kill();
+                let _ = child.wait();
+                return Err(if cancel.is_cancelled() {
+                    HostError::Cancelled
+                } else {
+                    HostError::Failed(format!("{program} timed out after {timeout:?}"))
+                });
+            }
+            std::thread::sleep(Duration::from_millis(10));
+        };
+        Ok(ProcessOutput {
+            status: status.code(),
+            stdout: stdout.join().unwrap_or_default(),
+            stderr: stderr.join().unwrap_or_default(),
+        })
+    }
+
+    fn subscribe(&self, kind: EventKind, on: bool) {
+        let changed = {
+            let mut subs = self.shared.subscriptions.lock();
+            let set = subs.entry(self.id().to_owned()).or_default();
+            if on { set.insert(kind) } else { set.remove(&kind) }
+        };
+        if changed {
+            self.shared.sink.emit(None, PluginEvent::SubscriptionsChanged);
+        }
+    }
+
+    fn task_begin(&self, client: Option<&str>, title: String, cancellable: bool, cancel: CancellationToken) -> u64 {
+        let id = self.shared.next_task.fetch_add(1, Ordering::Relaxed);
+        self.shared.tasks.lock().insert(id, TaskEntry { plugin: self.id().to_owned(), cancel, cancelled: false });
+        self.shared.sink.emit(
+            client,
+            PluginEvent::TaskStarted { plugin_id: self.id().to_owned(), task_id: id.to_string(), title, cancellable },
+        );
+        id
+    }
+
+    fn task_report(&self, id: u64, done: u32, total: Option<u32>, message: Option<String>) {
+        if !self.shared.tasks.lock().contains_key(&id) {
+            return;
+        }
+        self.shared.sink.emit(
+            None,
+            PluginEvent::TaskProgress {
+                plugin_id: self.id().to_owned(),
+                task_id: id.to_string(),
+                done,
+                total,
+                message,
+            },
+        );
+    }
+
+    fn task_cancelled(&self, id: u64) -> bool {
+        self.shared.tasks.lock().get(&id).is_some_and(|t| t.cancelled)
+    }
+
+    fn task_end(&self, id: u64) {
+        self.shared.end_task(id);
+    }
+
+    fn refresh_view(&self, view: &str) {
+        self.shared
+            .sink
+            .emit(None, PluginEvent::ViewChanged { plugin_id: self.id().to_owned(), view: view.to_owned() });
+    }
+
+    fn post_view_message(&self, view: &str, message: String) -> Result<(), HostError> {
+        let declared = [super::ui_points::VIEWS, super::ui_points::CUSTOM_EDITORS]
+            .iter()
+            .any(|point| self.shared.ui.items(point, Some(self.id())).iter().any(|i| i.key == view));
+        if !declared {
+            return Err(HostError::NotFound(format!("the plugin declares no view {view:?}")));
+        }
+        let event = PluginEvent::ViewMessage { plugin_id: self.id().to_owned(), view: view.to_owned(), message };
+        self.shared.sink.emit(None, event);
+        Ok(())
+    }
+
+    fn open_terminal(
+        &self,
+        client: Option<&str>,
+        title: String,
+        program: &str,
+        args: Vec<String>,
+        cwd: Option<&Path>,
+    ) -> Result<(), HostError> {
+        let binary = self.approved_program(program)?;
+        let cwd = cwd.map(Path::to_path_buf).unwrap_or_else(|| self.shared.data_dir.join(self.id()));
+        let _ = std::fs::create_dir_all(&cwd);
+        let event = PluginEvent::OpenTerminal {
+            plugin_id: self.id().to_owned(),
+            title,
+            program: binary.into(),
+            args,
+            cwd: cwd.into(),
+        };
+        self.shared.sink.emit(client, event);
+        Ok(())
+    }
+
+    fn setting(&self, root: Option<&Path>, key: &str) -> Option<String> {
+        let schema: Vec<super::ui_points::SettingSchema> = self
+            .shared
+            .ui
+            .items(super::ui_points::SETTINGS, Some(self.id()))
+            .into_iter()
+            .find_map(|i| serde_json::from_value(i.decl.get("properties")?.clone()).ok())?;
+        let setting = schema.into_iter().find(|s| s.key == key)?;
+        let user = self.shared.workspace().map(|w| w.plugin_settings(self.id(), root)).unwrap_or_default();
+        let value = user.get(key).filter(|v| setting.accepts(v)).cloned().unwrap_or(setting.default);
+        serde_json::to_string(&value).ok()
+    }
+}
+
+/// [`PluginWorkspace`] over the desktop host's open projects.
+pub struct HostWorkspace(pub std::sync::Weak<crate::Host>);
+
+impl HostWorkspace {
+    fn projects(&self) -> Vec<Arc<crate::project::Project>> {
+        self.0.upgrade().map(|h| h.projects()).unwrap_or_default()
+    }
+
+    /// The project holding an open document at `path`, and its id.
+    fn open_document(&self, path: &Path) -> Option<(Arc<crate::project::Project>, ide_core::DocId)> {
+        self.projects().into_iter().find_map(|p| p.documents.by_path(path).map(|doc| (p, doc)))
+    }
+}
+
+impl PluginWorkspace for HostWorkspace {
+    fn projects(&self) -> Vec<PathBuf> {
+        let mut roots: Vec<PathBuf> = HostWorkspace::projects(self).iter().map(|p| p.root.clone()).collect();
+        roots.sort();
+        roots.dedup();
+        roots
+    }
+
+    fn buffer_text(&self, path: &Path) -> Option<String> {
+        HostWorkspace::projects(self).iter().find_map(|p| p.documents.text_of(path))
+    }
+
+    fn document(&self, path: &Path) -> Option<(u64, String)> {
+        let (project, doc) = self.open_document(path)?;
+        let snap = project.documents.snapshot(doc).ok()?;
+        Some((u64::from(snap.version), snap.text))
+    }
+
+    fn apply_edits(&self, path: &Path, version: u64, edits: &[TextEdit]) -> Result<u64, HostError> {
+        let (project, doc) =
+            self.open_document(path).ok_or_else(|| HostError::NotFound(format!("{} is not open", path.display())))?;
+        let version = u32::try_from(version).map_err(|_| HostError::Stale)?;
+        match project.documents.apply_edits_at(doc, version, edits) {
+            Ok(Some(v)) => Ok(u64::from(v)),
+            Ok(None) => Err(HostError::Stale),
+            Err(e) if e.kind == ide_core::error::ErrorKind::InvalidInput => Err(HostError::Invalid(e.message)),
+            Err(e) => Err(HostError::Failed(e.message)),
+        }
+    }
+
+    fn trusted(&self, root: &Path) -> bool {
+        HostWorkspace::projects(self).iter().any(|p| p.root == root && p.is_trusted())
+    }
+
+    fn project_of(&self, window: &str) -> Option<PathBuf> {
+        self.0.upgrade()?.project(window).ok().map(|p| p.root.clone())
+    }
+
+    fn publish_diagnostics(
+        &self,
+        source: &str,
+        path: &Path,
+        items: Vec<ide_core::Diagnostic>,
+    ) -> Result<(), HostError> {
+        let projects = HostWorkspace::projects(self);
+        let project = projects
+            .iter()
+            .filter(|p| path.starts_with(&p.root))
+            .max_by_key(|p| p.root.as_os_str().len())
+            .ok_or_else(|| HostError::Invalid(format!("{} is not in an open project", path.display())))?;
+        project.sink.emit(ide_core::IdeEvent::Diagnostics {
+            path: path.to_path_buf().into(),
+            source: format!("plugin:{source}"),
+            items,
+        });
+        Ok(())
+    }
+
+    fn plugin_settings(&self, plugin: &str, root: Option<&Path>) -> serde_json::Map<String, serde_json::Value> {
+        let Some(host) = self.0.upgrade() else { return serde_json::Map::new() };
+        let settings = match root.and_then(|r| host.projects().into_iter().find(|p| p.root == r)) {
+            Some(p) => p.settings.effective(),
+            None => host.global_settings.effective(),
+        };
+        settings.plugins.get(plugin).cloned().unwrap_or_default()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn api(dir: &Path, pins: Arc<RwLock<HashMap<(String, String), ProgramPin>>>) -> PluginApi {
+        let manifest = ide_extension::Manifest::parse(
+            "id = \"acme.lint\"\nname = \"Lint\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n",
+        )
+        .unwrap();
+        let sink: Arc<dyn PluginEventSink> = Arc::new(|_: Option<&str>, _: PluginEvent| {});
+        let shared = Shared::new(sink, dir.join(".data"), pins, ide_extension::UiStore::new());
+        PluginApi { pkg: Package::new(manifest, dir.to_path_buf()), shared }
+    }
+
+    #[test]
+    fn programs_run_only_as_approved() {
+        let tmp = tempfile::tempdir().unwrap();
+        let bin = tmp.path().join("lint");
+        std::fs::write(&bin, "#!/bin/sh\n").unwrap();
+        let pins: Arc<RwLock<HashMap<(String, String), ProgramPin>>> = Arc::default();
+        let api = api(tmp.path(), pins.clone());
+
+        // Allowed while the program was missing: say how to fix it rather than "not granted".
+        let err = api.approved_program("lint").unwrap_err().to_string();
+        assert!(
+            err.contains("was not found when this permission was allowed") && err.contains("allow process:lint again"),
+            "{err}"
+        );
+
+        pins.write().insert(("acme.lint".into(), "process:lint".into()), ProgramPin::approve(&bin).unwrap());
+        assert_eq!(api.approved_program("lint").unwrap(), bin);
+
+        std::fs::write(&bin, "#!/bin/sh\necho replaced\n").unwrap();
+        assert!(
+            matches!(api.approved_program("lint"), Err(HostError::Denied(e)) if e.contains("changed since it was approved"))
+        );
+    }
+}

crates/ide-host/src/plugins/icons.rs

@@ -0,0 +1,615 @@
+//! The `iconThemes` extension point: file and folder icons.
+//!
+//! ```toml
+//! [[contributes.iconThemes]]
+//! id = "material"
+//! label = "Material Icons"
+//! path = "icons/theme.json"
+//! ```
+//!
+//! `theme.json` (paths relative to the package):
+//!
+//! ```json
+//! {
+//!   "iconDefinitions": { "rust": "icons/rust.svg", "folder-src": "icons/folder-src.svg" },
+//!   "file": "file", "folder": "folder", "folderExpanded": "folder-open",
+//!   "fileExtensions": { "rs": "rust" },
+//!   "fileNames": { "cargo.toml": "cargo" },
+//!   "folderNames": { "src": "folder-src" }
+//! }
+//! ```
+//!
+//! Every SVG is sanitised here (allow-listed elements and attributes, no
+//! scripts, event handlers, external references or entities) and stored as an
+//! asset; the client fetches the mapping and the icons only when the theme is
+//! selected, so installed icon themes cost nothing at start-up.
+
+use ide_extension::{Package, UiDecl, check_relative, decode, validate_item_id};
+use serde::Deserialize;
+use std::collections::{BTreeMap, BTreeSet};
+use std::path::PathBuf;
+
+pub const POINT_ID: &str = "iconThemes";
+const MAX_ICONS: usize = 5000;
+const MAX_SVG: usize = 64 << 10;
+const MAX_MAPPINGS: usize = 20_000;
+
+#[derive(Deserialize)]
+#[serde(deny_unknown_fields)]
+struct Decl {
+    id: String,
+    label: String,
+    path: PathBuf,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+struct ThemeFile {
+    icon_definitions: BTreeMap<String, PathBuf>,
+    #[serde(default)]
+    file: Option<String>,
+    #[serde(default)]
+    folder: Option<String>,
+    #[serde(default)]
+    folder_expanded: Option<String>,
+    #[serde(default)]
+    file_extensions: BTreeMap<String, String>,
+    #[serde(default)]
+    file_names: BTreeMap<String, String>,
+    #[serde(default)]
+    folder_names: BTreeMap<String, String>,
+}
+
+/// Asset id of a theme's mapping (JSON).
+pub fn map_asset(theme: &str) -> String {
+    format!("iconTheme/{theme}/map")
+}
+
+/// Asset id prefix of a theme's SVGs (`…/svg/<icon id>`).
+pub fn svg_prefix(theme: &str) -> String {
+    format!("iconTheme/{theme}/svg/")
+}
+
+/// An SVG icon of the package, size-checked and sanitised.
+pub(super) fn read_icon(pkg: &Package, path: &std::path::Path) -> Result<String, String> {
+    check_relative(path, "icon")?;
+    let svg = pkg.read_text(path)?;
+    if svg.len() > MAX_SVG {
+        return Err(format!("{}: larger than {} KiB", path.display(), MAX_SVG >> 10));
+    }
+    sanitize_svg(&svg).map_err(|e| format!("{}: {e}", path.display()))
+}
+
+pub(super) fn icon_theme(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: Decl = decode(POINT_ID, decl)?;
+    validate_item_id(&d.id, "icon theme id")?;
+    if d.label.trim().is_empty() {
+        return Err(format!("icon theme {:?} has an empty label", d.id));
+    }
+    let src = pkg.read_text(&d.path)?;
+    let theme: ThemeFile = serde_json::from_str(&src).map_err(|e| format!("{}: {e}", d.path.display()))?;
+    let at = |what: &str| format!("{} ({what})", d.path.display());
+    if theme.icon_definitions.len() > MAX_ICONS {
+        return Err(format!("{}: more than {MAX_ICONS} icons", d.path.display()));
+    }
+    let mappings = theme.file_extensions.len() + theme.file_names.len() + theme.folder_names.len();
+    if mappings > MAX_MAPPINGS {
+        return Err(format!("{}: more than {MAX_MAPPINGS} mappings", d.path.display()));
+    }
+    let defined: BTreeSet<&str> = theme.icon_definitions.keys().map(String::as_str).collect();
+    let check_ref = |icon: &str, what: &str| -> Result<(), String> {
+        if defined.contains(icon) { Ok(()) } else { Err(format!("{}: unknown icon {icon:?}", at(what))) }
+    };
+    for (what, icon) in [("file", &theme.file), ("folder", &theme.folder), ("folderExpanded", &theme.folder_expanded)] {
+        if let Some(icon) = icon {
+            check_ref(icon, what)?;
+        }
+    }
+    // Extensions may be written with their dot (`.rs`); names keep theirs (`.github`, `.gitignore`).
+    let lower = |map: &BTreeMap<String, String>, what: &str| -> Result<BTreeMap<String, String>, String> {
+        let mut out = BTreeMap::new();
+        for (k, icon) in map {
+            check_ref(icon, what)?;
+            let key = k.trim();
+            let key = if what == "fileExtensions" { key.trim_start_matches('.') } else { key }.to_lowercase();
+            if key.is_empty() || key.contains(['/', '\\']) {
+                return Err(format!("{}: invalid key {k:?}", at(what)));
+            }
+            out.insert(key, icon.clone());
+        }
+        Ok(out)
+    };
+    let file_extensions = lower(&theme.file_extensions, "fileExtensions")?;
+    let file_names = lower(&theme.file_names, "fileNames")?;
+    let folder_names = lower(&theme.folder_names, "folderNames")?;
+
+    let mut assets = Vec::with_capacity(theme.icon_definitions.len() + 1);
+    let mut files = vec![d.path.clone()];
+    for (icon, path) in &theme.icon_definitions {
+        validate_item_id(icon, "icon id")?;
+        let clean = read_icon(pkg, path)?;
+        assets.push((format!("{}{icon}", svg_prefix(&d.id)), clean));
+        files.push(path.clone());
+    }
+    let map = serde_json::json!({
+        "file": theme.file,
+        "folder": theme.folder,
+        "folderExpanded": theme.folder_expanded,
+        "fileExtensions": file_extensions,
+        "fileNames": file_names,
+        "folderNames": folder_names,
+    });
+    assets.push((map_asset(&d.id), map.to_string()));
+    let json = serde_json::json!({ "id": d.id, "label": d.label, "icons": theme.icon_definitions.len() });
+    let mut out = UiDecl::new(d.id.clone(), d.label, json);
+    out.files = files;
+    out.assets = assets;
+    Ok(out)
+}
+
+// ---------------------------------------------------------------------------
+// SVG sanitiser
+
+const ELEMENTS: &[&str] = &[
+    "svg",
+    "g",
+    "path",
+    "circle",
+    "ellipse",
+    "line",
+    "polyline",
+    "polygon",
+    "rect",
+    "defs",
+    "lineargradient",
+    "radialgradient",
+    "stop",
+    "clippath",
+    "mask",
+    "use",
+    "symbol",
+    "pattern",
+    "text",
+    "tspan",
+    "filter",
+    "fegaussianblur",
+    "feoffset",
+    "feblend",
+    "fecolormatrix",
+    "feflood",
+    "fecomposite",
+    "femerge",
+    "femergenode",
+    "fedropshadow",
+];
+
+/// Dropped with their content: harmless metadata.
+const STRIPPED: &[&str] = &["title", "desc", "metadata"];
+
+const ATTRIBUTES: &[&str] = &[
+    "id",
+    "class",
+    "viewbox",
+    "width",
+    "height",
+    "x",
+    "y",
+    "x1",
+    "y1",
+    "x2",
+    "y2",
+    "cx",
+    "cy",
+    "r",
+    "rx",
+    "ry",
+    "fx",
+    "fy",
+    "d",
+    "points",
+    "transform",
+    "fill",
+    "fill-opacity",
+    "fill-rule",
+    "clip-rule",
+    "clip-path",
+    "mask",
+    "stroke",
+    "stroke-width",
+    "stroke-linecap",
+    "stroke-linejoin",
+    "stroke-miterlimit",
+    "stroke-dasharray",
+    "stroke-dashoffset",
+    "stroke-opacity",
+    "opacity",
+    "offset",
+    "stop-color",
+    "stop-opacity",
+    "gradientunits",
+    "gradienttransform",
+    "spreadmethod",
+    "patternunits",
+    "patterncontentunits",
+    "patterntransform",
+    "clippathunits",
+    "maskunits",
+    "maskcontentunits",
+    "preserveaspectratio",
+    "style",
+    "href",
+    "xlink:href",
+    "xmlns",
+    "xmlns:xlink",
+    "version",
+    "font-family",
+    "font-size",
+    "font-weight",
+    "text-anchor",
+    "dominant-baseline",
+    "letter-spacing",
+    "display",
+    "visibility",
+    "color",
+    "filter",
+    "in",
+    "in2",
+    "result",
+    "stddeviation",
+    "dx",
+    "dy",
+    "mode",
+    "operator",
+    "values",
+    "type",
+    "flood-color",
+    "flood-opacity",
+    "k1",
+    "k2",
+    "k3",
+    "k4",
+    "filterunits",
+    "primitiveunits",
+    "vector-effect",
+    "shape-rendering",
+    "isolation",
+    "mix-blend-mode",
+];
+
+/// Parses `src` and re-serialises the allow-listed subset. Fails on anything
+/// that could execute, fetch or escape (scripts, `foreignObject`, event
+/// handlers, external `href`s, `url()` to anything but a local fragment,
+/// DTDs, entities, CDATA).
+pub fn sanitize_svg(src: &str) -> Result<String, String> {
+    let mut out = String::with_capacity(src.len());
+    let mut stack: Vec<String> = Vec::new();
+    // Depth inside a stripped element (its content is skipped).
+    let mut skip_depth = 0usize;
+    let mut seen_root = false;
+    let mut rest = src;
+    while !rest.is_empty() {
+        let Some(lt) = rest.find('<') else {
+            if skip_depth == 0 && !stack.is_empty() {
+                out.push_str(&text(rest)?);
+            } else if !rest.trim().is_empty() && stack.is_empty() {
+                return Err("text outside the <svg> element".into());
+            }
+            break;
+        };
+        if lt > 0 {
+            let t = &rest[..lt];
+            if skip_depth == 0 && !stack.is_empty() {
+                out.push_str(&text(t)?);
+            } else if stack.is_empty() && !t.trim().is_empty() {
+                return Err("text outside the <svg> element".into());
+            }
+        }
+        rest = &rest[lt..];
+        if let Some(after) = rest.strip_prefix("<!--") {
+            let end = after.find("-->").ok_or("unterminated comment")?;
+            rest = &after[end + 3..];
+            continue;
+        }
+        if rest.starts_with("<?") {
+            let end = rest.find("?>").ok_or("unterminated processing instruction")?;
+            rest = &rest[end + 2..];
+            continue;
+        }
+        if rest.starts_with("<!") {
+            return Err("DTDs, entities and CDATA are not allowed".into());
+        }
+        if let Some(after) = rest.strip_prefix("</") {
+            let end = after.find('>').ok_or("unterminated closing tag")?;
+            let name = after[..end].trim().to_ascii_lowercase();
+            rest = &after[end + 1..];
+            let open = stack.pop().ok_or_else(|| format!("unexpected </{name}>"))?;
+            if open != name {
+                return Err(format!("</{name}> does not close <{open}>"));
+            }
+            if skip_depth > 0 {
+                skip_depth -= 1;
+            } else {
+                out.push_str(&format!("</{name}>"));
+            }
+            continue;
+        }
+        // Start tag.
+        let end = tag_end(rest).ok_or("unterminated tag")?;
+        let inner = &rest[1..end];
+        rest = &rest[end + 1..];
+        let self_closing = inner.trim_end().ends_with('/');
+        let inner = inner.trim_end().trim_end_matches('/');
+        let name_end = inner.find(|c: char| c.is_whitespace()).unwrap_or(inner.len());
+        let raw_name = &inner[..name_end];
+        let name = raw_name.to_ascii_lowercase();
+        if name.is_empty() {
+            return Err("empty tag".into());
+        }
+        if stack.is_empty() {
+            if seen_root || name != "svg" {
+                return Err("the file must contain exactly one <svg> element".into());
+            }
+            seen_root = true;
+        }
+        if !self_closing {
+            stack.push(name.clone());
+        }
+        if skip_depth > 0 {
+            if !self_closing {
+                skip_depth += 1;
+            }
+            continue;
+        }
+        if STRIPPED.contains(&name.as_str()) || name.contains(':') {
+            // Editor metadata (sodipodi:namedview) or descriptive text.
+            if !self_closing {
+                skip_depth = 1;
+            }
+            continue;
+        }
+        if !ELEMENTS.contains(&name.as_str()) {
+            return Err(format!("<{raw_name}> is not allowed"));
+        }
+        out.push('<');
+        out.push_str(raw_name);
+        for (attr, value) in attributes(&inner[name_end..])? {
+            let key = attr.to_ascii_lowercase();
+            if key.starts_with("on") {
+                return Err(format!("event handler {attr} is not allowed"));
+            }
+            if key.contains(':') && !matches!(key.as_str(), "xlink:href" | "xmlns:xlink") {
+                continue; // inkscape:label, sodipodi:docname, …
+            }
+            if !ATTRIBUTES.contains(&key.as_str()) && !key.starts_with("data-") && !key.starts_with("aria-") {
+                return Err(format!("attribute {attr} is not allowed"));
+            }
+            check_value(&key, &value).map_err(|e| format!("{attr}: {e}"))?;
+            out.push(' ');
+            out.push_str(&attr);
+            out.push_str("=\"");
+            out.push_str(&escape(&value));
+            out.push('"');
+        }
+        out.push_str(if self_closing { "/>" } else { ">" });
+    }
+    if !stack.is_empty() {
+        return Err(format!("<{}> is not closed", stack.last().map(String::as_str).unwrap_or("?")));
+    }
+    if !seen_root {
+        return Err("no <svg> element".into());
+    }
+    Ok(out)
+}
+
+/// Index of the `>` ending the tag at the start of `s`, skipping quoted values.
+fn tag_end(s: &str) -> Option<usize> {
+    let mut quote: Option<char> = None;
+    for (i, c) in s.char_indices().skip(1) {
+        match (quote, c) {
+            (Some(q), c) if c == q => quote = None,
+            (Some(_), _) => {}
+            (None, '"' | '\'') => quote = Some(c),
+            (None, '>') => return Some(i),
+            (None, '<') => return None,
+            _ => {}
+        }
+    }
+    None
+}
+
+fn attributes(s: &str) -> Result<Vec<(String, String)>, String> {
+    let mut out = Vec::new();
+    let mut rest = s.trim_start();
+    while !rest.is_empty() {
+        let eq = rest.find('=').ok_or_else(|| format!("attribute without value near {:?}", clip(rest)))?;
+        let name = rest[..eq].trim();
+        if name.is_empty() || name.contains(|c: char| c.is_whitespace() || c == '"' || c == '\'') {
+            return Err(format!("malformed attribute near {:?}", clip(rest)));
+        }
+        let after = rest[eq + 1..].trim_start();
+        let quote = after.chars().next().filter(|c| *c == '"' || *c == '\'').ok_or("unquoted attribute value")?;
+        let close = after[1..].find(quote).ok_or("unterminated attribute value")?;
+        let value = decode_entities(&after[1..1 + close])?;
+        if out.iter().any(|(n, _): &(String, String)| n.eq_ignore_ascii_case(name)) {
+            return Err(format!("duplicate attribute {name}"));
+        }
+        out.push((name.to_owned(), value));
+        rest = after[close + 2..].trim_start();
+    }
+    Ok(out)
+}
+
+fn check_value(key: &str, value: &str) -> Result<(), String> {
+    let lower = value.to_ascii_lowercase();
+    if matches!(key, "href" | "xlink:href") {
+        return if value.starts_with('#') { Ok(()) } else { Err("only local references (#id) are allowed".into()) };
+    }
+    if key == "xmlns" || key == "xmlns:xlink" {
+        return Ok(());
+    }
+    if lower.contains("javascript:")
+        || lower.contains("expression(")
+        || lower.contains("@import")
+        || value.contains('\\')
+    {
+        return Err("unsafe value".into());
+    }
+    let mut rest = lower.as_str();
+    while let Some(i) = rest.find("url(") {
+        let inner = rest[i + 4..].trim_start().trim_start_matches(['"', '\'']);
+        if !inner.starts_with('#') {
+            return Err("url() may only reference a local fragment".into());
+        }
+        rest = &rest[i + 4..];
+    }
+    Ok(())
+}
+
+fn decode_entities(s: &str) -> Result<String, String> {
+    if !s.contains('&') {
+        return Ok(s.to_owned());
+    }
+    let mut out = String::with_capacity(s.len());
+    let mut rest = s;
+    while let Some(i) = rest.find('&') {
+        out.push_str(&rest[..i]);
+        let semi = rest[i..].find(';').ok_or("unterminated entity")?;
+        let ent = &rest[i + 1..i + semi];
+        let c = match ent {
+            "amp" => '&',
+            "lt" => '<',
+            "gt" => '>',
+            "quot" => '"',
+            "apos" => '\'',
+            _ => {
+                let code = if let Some(hex) = ent.strip_prefix("#x").or_else(|| ent.strip_prefix("#X")) {
+                    u32::from_str_radix(hex, 16).ok()
+                } else if let Some(dec) = ent.strip_prefix('#') {
+                    dec.parse().ok()
+                } else {
+                    None
+                };
+                code.and_then(char::from_u32).ok_or_else(|| format!("entity &{ent}; is not allowed"))?
+            }
+        };
+        out.push(c);
+        rest = &rest[i + semi + 1..];
+    }
+    out.push_str(rest);
+    Ok(out)
+}
+
+fn text(t: &str) -> Result<String, String> {
+    Ok(escape(&decode_entities(t)?))
+}
+
+fn escape(s: &str) -> String {
+    s.replace('&', "&amp;").replace('<', "&lt;").replace('>', "&gt;").replace('"', "&quot;")
+}
+
+fn clip(s: &str) -> &str {
+    let mut end = s.len().min(24);
+    while !s.is_char_boundary(end) {
+        end -= 1;
+    }
+    &s[..end]
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn keeps_ordinary_icons() {
+        let src = r##"<?xml version="1.0"?>
+<!-- Material icon -->
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:inkscape="x" viewBox="0 0 24 24" inkscape:version="1">
+  <title>rust</title>
+  <defs><linearGradient id="g"><stop offset="0" stop-color="#fff"/></linearGradient></defs>
+  <path fill="url(#g)" d="M1 2h3 &amp; 4" style="opacity:.5"/>
+  <use href="#g"/>
+</svg>"##;
+        let out = sanitize_svg(src).unwrap();
+        assert!(out.starts_with("<svg xmlns="), "{out}");
+        assert!(!out.contains("title") && !out.contains("inkscape") && !out.contains("<!--"));
+        assert!(out.contains(r#"fill="url(#g)""#));
+        assert!(out.contains(r#"d="M1 2h3 &amp; 4""#));
+        assert!(out.ends_with("</svg>"));
+    }
+
+    #[test]
+    fn rejects_active_content() {
+        let bad = [
+            r##"<svg><script>alert(1)</script></svg>"##,
+            r##"<svg onload="alert(1)"></svg>"##,
+            r##"<svg><foreignObject/></svg>"##,
+            r##"<svg><use href="https://evil/x.svg#a"/></svg>"##,
+            r##"<svg><use xlink:href="data:image/svg+xml,..."/></svg>"##,
+            r##"<svg><rect style="fill:url(https://evil)"/></svg>"##,
+            r##"<svg><rect fill="url( 'http://x' )"/></svg>"##,
+            r##"<!DOCTYPE svg [<!ENTITY x "y">]><svg/>"##,
+            r##"<svg><![CDATA[x]]></svg>"##,
+            r##"<svg><a href="#x"/></svg>"##,
+            r##"<svg><rect width="&xx;"/></svg>"##,
+            r##"<svg><rect width=10/></svg>"##,
+            r##"<svg><g></svg>"##,
+            r##"<svg/><svg/>"##,
+            r##"<g/>"##,
+            r##"hello"##,
+            r##"<svg><rect style="behavior:url(#x);x:expression(1)"/></svg>"##,
+        ];
+        for src in bad {
+            assert!(sanitize_svg(src).is_err(), "accepted: {src}");
+        }
+    }
+
+    #[test]
+    fn theme_files_validate_and_produce_assets() {
+        let tmp = tempfile::tempdir().unwrap();
+        let dir = tmp.path();
+        std::fs::create_dir_all(dir.join("icons")).unwrap();
+        std::fs::write(dir.join("icons/rust.svg"), r#"<svg viewBox="0 0 16 16"><path d="M0 0h16v16z"/></svg>"#)
+            .unwrap();
+        std::fs::write(dir.join("icons/file.svg"), r#"<svg viewBox="0 0 16 16"><rect width="16" height="16"/></svg>"#)
+            .unwrap();
+        std::fs::write(
+            dir.join("theme.json"),
+            r#"{"iconDefinitions":{"rust":"icons/rust.svg","file":"icons/file.svg"},"file":"file",
+                "fileExtensions":{".RS":"rust"},"fileNames":{"Cargo.toml":"rust",".gitignore":"file"},
+                "folderNames":{".GitHub":"file","src":"rust"}}"#,
+        )
+        .unwrap();
+        let manifest = ide_extension::Manifest::parse(
+            "id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"",
+        )
+        .unwrap();
+        let pkg = Package::new(manifest, dir.to_path_buf());
+        let decl = |path: &str| {
+            let mut t = toml::Table::new();
+            t.insert("id".into(), "m".into());
+            t.insert("label".into(), "M".into());
+            t.insert("path".into(), path.into());
+            toml::Value::Table(t)
+        };
+        let d = icon_theme(&pkg, decl("theme.json")).unwrap();
+        assert_eq!(d.json["icons"], 2);
+        assert_eq!(d.files.len(), 3);
+        let map: serde_json::Value =
+            serde_json::from_str(&d.assets.iter().find(|(k, _)| *k == map_asset("m")).unwrap().1).unwrap();
+        assert_eq!(map["fileExtensions"]["rs"], "rust");
+        assert_eq!(map["fileNames"]["cargo.toml"], "rust");
+        // Names keep their leading dot (only extensions drop it).
+        assert_eq!(map["fileNames"][".gitignore"], "file");
+        assert_eq!(map["folderNames"][".github"], "file");
+        assert_eq!(map["folderNames"]["src"], "rust");
+        assert!(map["folderNames"].get("github").is_none());
+        assert!(d.assets.iter().any(|(k, _)| *k == format!("{}rust", svg_prefix("m"))));
+
+        std::fs::write(dir.join("bad.json"), r#"{"iconDefinitions":{},"fileExtensions":{"rs":"nope"}}"#).unwrap();
+        assert!(icon_theme(&pkg, decl("bad.json")).unwrap_err().contains("unknown icon"));
+        std::fs::write(dir.join("icons/evil.svg"), r#"<svg><script/></svg>"#).unwrap();
+        std::fs::write(dir.join("evil.json"), r#"{"iconDefinitions":{"e":"icons/evil.svg"}}"#).unwrap();
+        assert!(icon_theme(&pkg, decl("evil.json")).unwrap_err().contains("evil.svg"));
+        assert!(icon_theme(&pkg, decl("../x.json")).is_err());
+    }
+}

crates/ide-host/src/plugins/install.rs

@@ -0,0 +1,288 @@
+//! Copying a package into the plugins directory without ever leaving the
+//! plugin missing. Installed plugins are versioned:
+//! `<plugins>/<id>/<version>/` plus an `active` pointer file (and `previous`,
+//! the version to roll back to). A new version is written to a staging
+//! directory, renamed into place, and only then made active by replacing the
+//! pointer; a swap interrupted by a crash is undone on the next start
+//! ([`recover`]). Older installs used `<plugins>/<id>/` directly; they are
+//! moved into the versioned layout on their next update.
+
+use std::io;
+use std::path::{Path, PathBuf};
+use std::time::{SystemTime, UNIX_EPOCH};
+
+/// Top-level files copied with a package besides those its declarations reference.
+pub const LICENSE_FILES: &[&str] =
+    &["LICENSE", "LICENSE.md", "LICENSE.txt", "NOTICE", "NOTICE.md", "NOTICE.txt", "COPYING", "README.md"];
+/// Written into an installed package: the package hash the grant ledger compares.
+pub const HASH_FILE: &str = ".package-hash";
+
+const STAGING: &str = ".staging-";
+const OLD: &str = ".old-";
+/// `<root>/active`: the version in use.
+pub const ACTIVE_FILE: &str = "active";
+/// `<root>/previous`: the version an update replaced (for rollback).
+pub const PREVIOUS_FILE: &str = "previous";
+
+fn nonce() -> String {
+    let n = SystemTime::now().duration_since(UNIX_EPOCH).map(|d| d.as_nanos()).unwrap_or_default();
+    format!("{n:x}-{}", std::process::id())
+}
+
+/// Copies `files` (plus manifest and licence files) from `src` into `target`
+/// atomically, recording `hash`.
+pub fn install_package(src: &Path, target: &Path, files: &[PathBuf], hash: &str) -> io::Result<()> {
+    let parent = target.parent().ok_or_else(|| io::Error::other("plugin target has no parent"))?;
+    let name = target.file_name().and_then(|n| n.to_str()).ok_or_else(|| io::Error::other("bad target"))?;
+    std::fs::create_dir_all(parent)?;
+    let staging = parent.join(format!("{STAGING}{name}-{}", nonce()));
+    let result = (|| {
+        std::fs::create_dir_all(&staging)?;
+        std::fs::copy(src.join(ide_extension::MANIFEST_FILE), staging.join(ide_extension::MANIFEST_FILE))?;
+        for file in files {
+            let to = staging.join(file);
+            if let Some(dir) = to.parent() {
+                std::fs::create_dir_all(dir)?;
+            }
+            std::fs::copy(src.join(file), to)?;
+        }
+        for lic in LICENSE_FILES {
+            if src.join(lic).is_file() {
+                std::fs::copy(src.join(lic), staging.join(lic))?;
+            }
+        }
+        std::fs::write(staging.join(HASH_FILE), hash)?;
+        swap(&staging, target, |from, to| std::fs::rename(from, to))
+    })();
+    if result.is_err() {
+        let _ = std::fs::remove_dir_all(&staging);
+    }
+    result
+}
+
+/// A version as a directory name (semver: `[0-9A-Za-z.+-]`).
+fn version_dir(version: &str) -> io::Result<&str> {
+    let ok = !version.is_empty()
+        && version.len() <= 64
+        && !version.starts_with('.')
+        && version.chars().all(|c| c.is_ascii_alphanumeric() || matches!(c, '.' | '+' | '-'));
+    if ok { Ok(version) } else { Err(io::Error::other(format!("version {version:?} cannot name a directory"))) }
+}
+
+fn read_pointer(root: &Path, name: &str) -> Option<String> {
+    let v = std::fs::read_to_string(root.join(name)).ok()?;
+    let v = v.trim();
+    (!v.is_empty() && version_dir(v).is_ok()).then(|| v.to_owned())
+}
+
+/// Replaces the pointer file `name` atomically.
+fn write_pointer(root: &Path, name: &str, version: &str) -> io::Result<()> {
+    let tmp = root.join(format!(".{name}.tmp"));
+    std::fs::write(&tmp, version)?;
+    std::fs::rename(&tmp, root.join(name))
+}
+
+/// The directory of a plugin's active version under its `root`
+/// (`<plugins>/<id>`): `<root>/<active>`, or `root` itself in the flat layout.
+pub fn active_dir(root: &Path) -> Option<PathBuf> {
+    if let Some(v) = read_pointer(root, ACTIVE_FILE) {
+        let dir = root.join(v);
+        return dir.join(ide_extension::MANIFEST_FILE).is_file().then_some(dir);
+    }
+    root.join(ide_extension::MANIFEST_FILE).is_file().then(|| root.to_path_buf())
+}
+
+/// The version an update replaced, if it is still there.
+pub fn previous_version(root: &Path) -> Option<String> {
+    read_pointer(root, PREVIOUS_FILE).filter(|v| root.join(v).join(ide_extension::MANIFEST_FILE).is_file())
+}
+
+/// Moves a flat install (`<root>/plugin.toml`) to `<root>/<version>/`.
+fn migrate_flat(root: &Path, version_of: impl Fn(&Path) -> Option<String>) -> io::Result<()> {
+    if read_pointer(root, ACTIVE_FILE).is_some() || !root.join(ide_extension::MANIFEST_FILE).is_file() {
+        return Ok(());
+    }
+    let version = version_of(root).unwrap_or_else(|| "0.0.0".into());
+    let version = version_dir(&version).map(str::to_owned).unwrap_or_else(|_| "0.0.0".into());
+    let parent = root.parent().unwrap_or(Path::new("."));
+    let name = root.file_name().and_then(|n| n.to_str()).ok_or_else(|| io::Error::other("bad plugin directory"))?;
+    // `.old-<name>-…` is restored by `recover` if this is interrupted.
+    let old = parent.join(format!("{OLD}{name}-{}", nonce()));
+    std::fs::rename(root, &old)?;
+    std::fs::create_dir_all(root)?;
+    std::fs::rename(&old, root.join(&version))?;
+    write_pointer(root, ACTIVE_FILE, &version)
+}
+
+/// Installs `files` of `src` as `<root>/<version>` and makes it the active
+/// version. Returns the version it replaced (now `previous`).
+pub fn install_version(
+    src: &Path,
+    root: &Path,
+    version: &str,
+    files: &[PathBuf],
+    hash: &str,
+    version_of: impl Fn(&Path) -> Option<String>,
+) -> io::Result<Option<String>> {
+    let version = version_dir(version)?;
+    std::fs::create_dir_all(root)?;
+    migrate_flat(root, version_of)?;
+    install_package(src, &root.join(version), files, hash)?;
+    let previous = read_pointer(root, ACTIVE_FILE).filter(|v| v != version);
+    if let Some(p) = &previous {
+        write_pointer(root, PREVIOUS_FILE, p)?;
+    }
+    write_pointer(root, ACTIVE_FILE, version)?;
+    Ok(previous)
+}
+
+/// Makes `version` active again (rollback). The replaced version stays until [`prune`].
+pub fn activate_version(root: &Path, version: &str) -> io::Result<()> {
+    let version = version_dir(version)?;
+    if !root.join(version).join(ide_extension::MANIFEST_FILE).is_file() {
+        return Err(io::Error::other(format!("version {version} is not installed")));
+    }
+    let _ = std::fs::remove_file(root.join(PREVIOUS_FILE));
+    write_pointer(root, ACTIVE_FILE, version)
+}
+
+/// Removes versions other than the active and the previous one.
+pub fn prune(root: &Path) {
+    let keep: Vec<String> = [ACTIVE_FILE, PREVIOUS_FILE].iter().filter_map(|f| read_pointer(root, f)).collect();
+    if keep.is_empty() {
+        return;
+    }
+    let Ok(entries) = std::fs::read_dir(root) else { return };
+    for e in entries.flatten() {
+        let path = e.path();
+        let name = e.file_name().to_string_lossy().into_owned();
+        if path.is_dir() && !keep.contains(&name) {
+            let _ = std::fs::remove_dir_all(&path);
+        }
+    }
+}
+
+/// Moves `staging` to `target`, keeping the old `target` until the new one is in place.
+fn swap(staging: &Path, target: &Path, rename: impl Fn(&Path, &Path) -> io::Result<()>) -> io::Result<()> {
+    if !target.exists() {
+        return rename(staging, target);
+    }
+    let parent = target.parent().unwrap_or(Path::new("."));
+    let name = target.file_name().and_then(|n| n.to_str()).unwrap_or("plugin");
+    let old = parent.join(format!("{OLD}{name}-{}", nonce()));
+    rename(target, &old)?;
+    if let Err(e) = rename(staging, target) {
+        // Put the previous version back.
+        rename(&old, target)?;
+        return Err(e);
+    }
+    if let Err(e) = std::fs::remove_dir_all(&old) {
+        tracing::warn!("removing the previous version {}: {e}", old.display());
+    }
+    Ok(())
+}
+
+/// Undoes interrupted installs in `dir`: restores `.old-<name>-*` when
+/// `<name>` is missing, and removes leftover staging and old directories.
+pub fn recover(dir: &Path) {
+    let Ok(entries) = std::fs::read_dir(dir) else { return };
+    for entry in entries.flatten() {
+        let path = entry.path();
+        // Inside a versioned plugin: staging and old versions of a version swap.
+        if path.is_dir() && read_pointer(&path, ACTIVE_FILE).is_some() {
+            recover(&path);
+            continue;
+        }
+        let Some(file) = path.file_name().and_then(|n| n.to_str()).map(str::to_owned) else { continue };
+        if file.starts_with(STAGING) {
+            let _ = std::fs::remove_dir_all(&path);
+        } else if let Some(rest) = file.strip_prefix(OLD) {
+            // `<name>-<nonce>-<pid>`: the name is everything before the last two parts.
+            let parts: Vec<&str> = rest.rsplitn(3, '-').collect();
+            let name = parts.get(2).copied().unwrap_or_default();
+            let target = dir.join(name);
+            // A layout migration interrupted after creating the new root: it is still empty.
+            if !name.is_empty() && target.is_dir() && active_dir(&target).is_none() {
+                let _ = std::fs::remove_dir_all(&target);
+            }
+            if !name.is_empty() && !target.exists() {
+                tracing::warn!("restoring {} after an interrupted install", target.display());
+                let _ = std::fs::rename(&path, &target);
+            } else {
+                let _ = std::fs::remove_dir_all(&path);
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn failed_swap_keeps_the_old_version() {
+        let tmp = tempfile::tempdir().unwrap();
+        let target = tmp.path().join("p");
+        let staging = tmp.path().join(".staging-p-1");
+        std::fs::create_dir_all(&target).unwrap();
+        std::fs::write(target.join("v"), "1").unwrap();
+        std::fs::create_dir_all(&staging).unwrap();
+        std::fs::write(staging.join("v"), "2").unwrap();
+        let calls = std::cell::Cell::new(0);
+        let err = swap(&staging, &target, |a, b| {
+            calls.set(calls.get() + 1);
+            if calls.get() == 2 { Err(io::Error::other("disk full")) } else { std::fs::rename(a, b) }
+        });
+        assert!(err.is_err());
+        assert_eq!(std::fs::read_to_string(target.join("v")).unwrap(), "1");
+        swap(&staging, &target, |a, b| std::fs::rename(a, b)).unwrap();
+        assert_eq!(std::fs::read_to_string(target.join("v")).unwrap(), "2");
+        assert_eq!(std::fs::read_dir(tmp.path()).unwrap().count(), 1, "old version removed");
+    }
+
+    #[test]
+    fn versions_are_installed_side_by_side_and_rolled_back() {
+        let tmp = tempfile::tempdir().unwrap();
+        let src = tmp.path().join("src");
+        std::fs::create_dir_all(&src).unwrap();
+        let root = tmp.path().join("plugins/acme.tools");
+        let version_of = |_: &Path| Some("0.9.0".to_owned());
+        // A flat install from before versioning.
+        std::fs::create_dir_all(&root).unwrap();
+        std::fs::write(root.join(ide_extension::MANIFEST_FILE), "v0.9").unwrap();
+        assert_eq!(active_dir(&root), Some(root.clone()));
+
+        std::fs::write(src.join(ide_extension::MANIFEST_FILE), "v1").unwrap();
+        assert_eq!(install_version(&src, &root, "1.0.0", &[], "h1", version_of).unwrap().as_deref(), Some("0.9.0"));
+        assert_eq!(active_dir(&root), Some(root.join("1.0.0")));
+        std::fs::write(src.join(ide_extension::MANIFEST_FILE), "v2").unwrap();
+        assert_eq!(install_version(&src, &root, "2.0.0", &[], "h2", version_of).unwrap().as_deref(), Some("1.0.0"));
+        assert_eq!(previous_version(&root).as_deref(), Some("1.0.0"));
+        prune(&root);
+        assert!(!root.join("0.9.0").exists(), "older than previous: pruned");
+
+        activate_version(&root, "1.0.0").unwrap();
+        assert_eq!(
+            std::fs::read_to_string(active_dir(&root).unwrap().join(ide_extension::MANIFEST_FILE)).unwrap(),
+            "v1"
+        );
+        assert_eq!(previous_version(&root), None);
+        assert!(install_version(&src, &root, "../x", &[], "h", version_of).is_err());
+    }
+
+    #[test]
+    fn recover_restores_an_interrupted_swap() {
+        let tmp = tempfile::tempdir().unwrap();
+        std::fs::create_dir_all(tmp.path().join(".old-acme.tools-1a2b-77")).unwrap();
+        std::fs::write(tmp.path().join(".old-acme.tools-1a2b-77/v"), "1").unwrap();
+        std::fs::create_dir_all(tmp.path().join(".staging-acme.tools-1a2c-77")).unwrap();
+        std::fs::create_dir_all(tmp.path().join("x")).unwrap();
+        std::fs::create_dir_all(tmp.path().join(".old-x-1-2")).unwrap();
+        recover(tmp.path());
+        assert_eq!(std::fs::read_to_string(tmp.path().join("acme.tools/v")).unwrap(), "1");
+        let mut names: Vec<_> =
+            std::fs::read_dir(tmp.path()).unwrap().flatten().map(|e| e.file_name().into_string().unwrap()).collect();
+        names.sort();
+        assert_eq!(names, ["acme.tools", "x"]);
+    }
+}

crates/ide-host/src/plugins/market.rs

@@ -0,0 +1,314 @@
+//! The marketplace: a static index (`index.json` +
+//! packages, served from any URL or folder) lists publishers and their keys,
+//! plugins, and revocations. The host keeps the last index it read
+//! (`market-index.json`), checks signatures against it, and disables what it
+//! revokes — at start-up and on every refresh (the desktop refreshes daily).
+
+use super::{PluginHost, PluginSource, PluginStatus};
+use ide_core::{IdeError, IdeResult};
+use ide_extension::Manifest;
+use ide_extension::package::{self, Index, IndexEntry, PackageSignature, SIGNATURE_FILE};
+use serde::{Deserialize, Serialize};
+use std::path::{Path, PathBuf};
+
+/// The official marketplace: the index the release workflow publishes with
+/// the app, next to the signed packages of the official plugins.
+pub const OFFICIAL_INDEX: &str = "https://github.com/l0ng-ai/openidea/releases/latest/download/plugins-index.json";
+
+/// The last index read, in the plugins directory.
+pub const INDEX_FILE: &str = "market-index.json";
+const DOWNLOADS: &str = ".downloads";
+const MAX_INDEX: usize = 16 << 20;
+const MAX_PACKAGE: usize = 256 << 20;
+
+/// A marketplace entry with what is installed.
+#[derive(Clone, Debug, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct MarketPlugin {
+    #[serde(flatten)]
+    pub entry: IndexEntry,
+    /// Installed version, if any.
+    pub installed: Option<String>,
+}
+
+/// Reads `url`: `http(s)://…`, `file://…` or a local path.
+pub fn read_url(url: &str, max: usize) -> Result<Vec<u8>, String> {
+    if url.starts_with("https://") || url.starts_with("http://") {
+        let client = ide_http::client::shared().map_err(|e| e.message)?;
+        let url = url.to_owned();
+        return super::api::net_runtime().block_on(async move {
+            let response = client.get(&url).send().await.map_err(|e| format!("{url}: {e}"))?;
+            if !response.status().is_success() {
+                return Err(format!("{url}: HTTP {}", response.status()));
+            }
+            let bytes = response.bytes().await.map_err(|e| format!("{url}: {e}"))?;
+            if bytes.len() > max {
+                return Err(format!("{url}: larger than {} MiB", max >> 20));
+            }
+            Ok(bytes.to_vec())
+        });
+    }
+    let path = url.strip_prefix("file://").unwrap_or(url);
+    let bytes = std::fs::read(path).map_err(|e| format!("{path}: {e}"))?;
+    if bytes.len() > max {
+        return Err(format!("{path}: larger than {} MiB", max >> 20));
+    }
+    Ok(bytes)
+}
+
+/// `href` relative to the index at `base`: a URL, or a local path (with the
+/// platform's separators, e.g. `C:\\market\\index.json`).
+pub fn resolve(base: &str, href: &str) -> String {
+    if href.contains("://") || href.starts_with('/') || Path::new(href).is_absolute() {
+        return href.to_owned();
+    }
+    if base.contains("://") {
+        return match base.rfind('/') {
+            Some(i) => format!("{}/{href}", &base[..i]),
+            None => href.to_owned(),
+        };
+    }
+    match Path::new(base).parent() {
+        Some(dir) => dir.join(href).to_string_lossy().into_owned(),
+        None => href.to_owned(),
+    }
+}
+
+impl PluginHost {
+    pub(super) fn load_market_index(dir: &Path) -> Option<Index> {
+        let text = std::fs::read_to_string(dir.join(INDEX_FILE)).ok()?;
+        Index::parse(&text).map_err(|e| tracing::warn!("{INDEX_FILE}: {e}")).ok()
+    }
+
+    /// The marketplace index URL: the user's, else the default (none: no marketplace).
+    pub fn market_url(&self) -> Option<String> {
+        self.state.lock().market_url.clone().or_else(|| self.default_market_url.read().clone())
+    }
+
+    /// The marketplace used while the user has set none.
+    pub fn set_default_market_url(&self, url: Option<String>) {
+        *self.default_market_url.write() = url.filter(|u| !u.trim().is_empty());
+    }
+
+    pub fn set_market_url(&self, url: Option<String>) {
+        self.state.lock().market_url = url.filter(|u| !u.trim().is_empty());
+        self.save_state();
+    }
+
+    /// Reads the index again, keeps it, and applies its revocations.
+    pub fn refresh_market(&self) -> IdeResult<Vec<MarketPlugin>> {
+        let url = self.market_url().ok_or_else(|| IdeError::unavailable("no plugin marketplace is configured"))?;
+        let bytes = read_url(&url, MAX_INDEX).map_err(IdeError::unavailable)?;
+        let text = String::from_utf8(bytes).map_err(|_| IdeError::invalid("the index is not UTF-8"))?;
+        let index = Index::parse(&text).map_err(IdeError::invalid)?;
+        let _ = std::fs::write(self.plugins_dir.join(INDEX_FILE), &text);
+        *self.market.write() = Some(index);
+        // Trust may have changed: who signed what, what is revoked.
+        let installed: Vec<_> =
+            self.plugins.read().values().filter(|p| p.source == PluginSource::Installed).cloned().collect();
+        for plugin in installed {
+            let publisher = self.verified_publisher(plugin.dir());
+            plugin.meta.lock().publisher = publisher;
+        }
+        self.apply_revocations();
+        Ok(self.market_plugins())
+    }
+
+    /// The plugins of the last index read.
+    pub fn market_plugins(&self) -> Vec<MarketPlugin> {
+        let Some(index) = self.market.read().clone() else { return Vec::new() };
+        let plugins = self.plugins.read();
+        index
+            .plugins
+            .iter()
+            .filter(|e| index.revocation(&e.id, &e.version).is_none())
+            .cloned()
+            .map(|entry| {
+                let installed = plugins
+                    .get(&entry.id)
+                    .filter(|p| p.source == PluginSource::Installed)
+                    .map(|p| p.manifest().version.clone());
+                MarketPlugin { entry, installed }
+            })
+            .collect()
+    }
+
+    /// Downloads a marketplace plugin, checks it against the index (digest and
+    /// signature), and unpacks it for the install page. Returns the folder to
+    /// install from.
+    pub fn download_market_plugin(&self, id: &str) -> IdeResult<PathBuf> {
+        let url = self.market_url().ok_or_else(|| IdeError::unavailable("no plugin marketplace is configured"))?;
+        let index = self.market.read().clone().ok_or_else(|| IdeError::unavailable("refresh the marketplace first"))?;
+        let entry = index
+            .plugins
+            .iter()
+            .find(|e| e.id == id)
+            .cloned()
+            .ok_or_else(|| IdeError::not_found(format!("{id} is not in the marketplace")))?;
+        let bytes = read_url(&resolve(&url, &entry.download), MAX_PACKAGE).map_err(IdeError::unavailable)?;
+        let downloads = self.plugins_dir.join(DOWNLOADS);
+        std::fs::create_dir_all(&downloads)?;
+        let archive = downloads.join(format!("{}-{}.{}", entry.id, entry.version, package::PACKAGE_EXTENSION));
+        std::fs::write(&archive, bytes)?;
+        let dir = self.unpack_package(&archive)?;
+        let _ = std::fs::remove_file(&archive);
+        let manifest = Manifest::load(&dir).map_err(IdeError::invalid)?;
+        let files = self.package_files_in(&dir)?;
+        let digest = package::package_digest(&dir, &files)?;
+        if (manifest.id.as_str(), manifest.version.as_str(), digest.as_str())
+            != (&entry.id, &entry.version, &entry.digest)
+        {
+            let _ = std::fs::remove_dir_all(&dir);
+            return Err(IdeError::invalid("the download does not match the marketplace's entry"));
+        }
+        if self.verified_publisher(&dir).is_none() {
+            let _ = std::fs::remove_dir_all(&dir);
+            return Err(IdeError::invalid("the marketplace package is not signed by a trusted publisher"));
+        }
+        Ok(dir)
+    }
+
+    /// Unpacks a package file (`.oiplugin`, or a `.zip` of a package) next to the downloads; returns the folder.
+    pub fn unpack_package(&self, archive: &Path) -> IdeResult<PathBuf> {
+        let stem = archive.file_stem().and_then(|s| s.to_str()).unwrap_or("package");
+        let dir = self.plugins_dir.join(DOWNLOADS).join(format!("{stem}-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        let unpacked = package::unpack(archive, &dir).map_err(IdeError::invalid)?;
+        // Kept with the files: install checks it and keeps it with the installed copy.
+        if let Some(sig) = unpacked.signature {
+            let json = serde_json::to_string_pretty(&sig).map_err(|e| IdeError::internal(e.to_string()))?;
+            std::fs::write(dir.join(SIGNATURE_FILE), json)?;
+        }
+        Ok(dir)
+    }
+
+    /// Files of the package in `dir` (what its declarations reference, and
+    /// the component): what a package file holds besides the manifest.
+    pub fn package_files_of(&self, dir: &Path) -> IdeResult<Vec<PathBuf>> {
+        self.package_files_in(dir)
+    }
+
+    pub(super) fn package_files_in(&self, dir: &Path) -> IdeResult<Vec<PathBuf>> {
+        let manifest = Manifest::load(dir).map_err(IdeError::invalid)?;
+        let pkg = ide_extension::Package::new(manifest, dir.to_path_buf());
+        let set = self.registry.prepare(&pkg).map_err(IdeError::invalid)?;
+        Ok(set.files.into_iter().chain(pkg.manifest.wasm.clone()).collect())
+    }
+
+    /// The publisher whose valid, trusted signature the package in `dir` carries.
+    pub(super) fn verified_publisher(&self, dir: &Path) -> Option<String> {
+        let sig = read_signature(dir)?;
+        let index = self.market.read().clone()?;
+        let manifest = Manifest::load(dir).ok()?;
+        let files = self.package_files_in(dir).ok()?;
+        let digest = package::package_digest(dir, &files).ok()?;
+        index
+            .verify(&sig, &manifest.id, &manifest.version, &digest)
+            .map_err(|e| tracing::warn!("{}: {e}", dir.display()))
+            .ok()
+    }
+
+    /// A signature that is present but doesn't verify (tampered, foreign prefix,
+    /// revoked or unknown key): installing is refused.
+    pub(super) fn signature_problem(&self, dir: &Path) -> Option<String> {
+        let sig = read_signature(dir)?;
+        let manifest = Manifest::load(dir).ok()?;
+        let files = self.package_files_in(dir).ok()?;
+        let digest = package::package_digest(dir, &files).ok()?;
+        if let Err(e) = sig.check(&manifest.id, &manifest.version, &digest) {
+            return Some(e);
+        }
+        let index = self.market.read().clone()?;
+        index.verify(&sig, &manifest.id, &manifest.version, &digest).err()
+    }
+
+    /// Why an installed plugin must not run (index revocations, revoked signing key).
+    pub(super) fn revoked_reason(&self, id: &str, version: &str, dir: &Path) -> Option<String> {
+        let market = self.market.read();
+        let index = market.as_ref()?;
+        if let Some(r) = index.revocation(id, version) {
+            return Some(r.reason.clone());
+        }
+        let sig = read_signature(dir)?;
+        index.key_revoked(&sig.key).then(|| "its publisher's signing key was revoked".to_owned())
+    }
+
+    /// Disables installed plugins the index revokes (telling the user once),
+    /// and starts again those it no longer revokes.
+    pub(super) fn apply_revocations(&self) {
+        let installed: Vec<_> =
+            self.plugins.read().values().filter(|p| p.source == PluginSource::Installed).cloned().collect();
+        let mut changed = false;
+        for plugin in installed {
+            let reason = self.revoked_reason(plugin.id(), &plugin.manifest().version, plugin.dir());
+            let current = plugin.meta.lock().error.clone().filter(|e| e.starts_with("revoked: "));
+            match (reason, current) {
+                (Some(r), Some(c)) if c == format!("revoked: {r}") => {}
+                (Some(reason), was) => {
+                    self.stop(&plugin);
+                    {
+                        let mut meta = plugin.meta.lock();
+                        meta.status = PluginStatus::Failed;
+                        meta.error = Some(format!("revoked: {reason}"));
+                    }
+                    if was.is_none() {
+                        self.emit(
+                            None,
+                            super::PluginEvent::Notification {
+                                plugin_id: plugin.id().to_owned(),
+                                level: ide_plugin::NotificationLevel::Warning,
+                                title: format!("{} was disabled", plugin.manifest().name),
+                                body: format!("The marketplace revoked this plugin: {reason}"),
+                            },
+                        );
+                    }
+                    changed = true;
+                }
+                (None, Some(_)) => {
+                    {
+                        let mut meta = plugin.meta.lock();
+                        meta.status = PluginStatus::Inactive;
+                        meta.error = None;
+                    }
+                    if !self.state.lock().disabled.contains(plugin.id()) {
+                        self.start(&plugin);
+                    }
+                    changed = true;
+                }
+                (None, None) => {}
+            }
+        }
+        if changed {
+            self.changed();
+        }
+    }
+}
+
+pub(super) fn read_signature(dir: &Path) -> Option<PackageSignature> {
+    let text = std::fs::read_to_string(dir.join(SIGNATURE_FILE)).ok()?;
+    serde_json::from_str(&text).ok()
+}
+
+/// Keeps the signature of a package with its installed copy.
+pub(super) fn copy_signature(src: &Path, installed: &Path) {
+    if src.join(SIGNATURE_FILE).is_file() {
+        let _ = std::fs::copy(src.join(SIGNATURE_FILE), installed.join(SIGNATURE_FILE));
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn downloads_resolve_against_the_index() {
+        assert_eq!(resolve("https://x.dev/market/index.json", "p/a.oiplugin"), "https://x.dev/market/p/a.oiplugin");
+        assert_eq!(
+            Path::new(&resolve("/srv/market/index.json", "a.oiplugin")),
+            Path::new("/srv/market").join("a.oiplugin")
+        );
+        #[cfg(windows)]
+        assert_eq!(resolve(r"C:\market\index.json", "a.oiplugin"), r"C:\market\a.oiplugin");
+        assert_eq!(resolve("https://x.dev/index.json", "https://cdn.dev/a"), "https://cdn.dev/a");
+    }
+}

crates/ide-host/src/plugins/points.rs

@@ -0,0 +1,71 @@
+//! First-party extension points registered by the host, plus
+//! [`register_builtin_points`], the one place that lists them. Feature crates
+//! own their points (`ide_language::plugin_point`); adding a contribution type
+//! means adding a point here or in its crate, and a `defineUiPoint` projection
+//! on the client for `Ui` points — nothing else.
+
+use ide_extension::{ExtensionRegistry, Package, UiDecl, UiPoint, UiStore, decode, validate_item_id, validate_when};
+use ide_language::plugin_point::{LanguagesPoint, PluginLanguages};
+use serde::{Deserialize, Serialize};
+use std::sync::Arc;
+
+pub const COMMANDS: &str = "commands";
+const MAX_TITLE: usize = 256;
+
+/// `[[contributes.commands]]`: an action `plugin.<plugin-id>.<id>` in Search
+/// Everywhere and the keymap editor; shown before the plugin's code runs.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+pub struct CommandDecl {
+    pub id: String,
+    pub title: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub category: Option<String>,
+    /// Enablement, evaluated by the client against context keys (`editorLang == rust`).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub when: Option<String>,
+}
+
+fn command(_pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let c: CommandDecl = decode(COMMANDS, decl)?;
+    validate_item_id(&c.id, "command id")?;
+    if c.title.trim().is_empty() {
+        return Err(format!("command {:?} has an empty title", c.id));
+    }
+    if c.title.len() > MAX_TITLE || c.category.as_ref().is_some_and(|x| x.len() > MAX_TITLE) {
+        return Err(format!("command {:?}: title or category longer than {MAX_TITLE} bytes", c.id));
+    }
+    if let Some(when) = &c.when {
+        validate_when(when).map_err(|e| format!("command {:?}: {e}", c.id))?;
+    }
+    let c = CommandDecl { category: c.category.filter(|x| !x.trim().is_empty()), ..c };
+    let json = serde_json::to_value(&c).map_err(|e| e.to_string())?;
+    Ok(UiDecl::new(c.id.clone(), c.title, json))
+}
+
+/// Registers every first-party extension point.
+pub fn register_builtin_points(
+    registry: &ExtensionRegistry,
+    ui: &Arc<UiStore>,
+    languages: &Arc<PluginLanguages>,
+    run_detectors: &Arc<super::run_detectors::RunDetectors>,
+    providers: &Arc<super::providers::Providers>,
+) -> Result<(), String> {
+    registry.register(Arc::new(UiPoint::new(COMMANDS, ui.clone(), command)))?;
+    registry.register(Arc::new(super::theme::ThemesPoint::new(ui.clone())))?;
+    registry.register(Arc::new(LanguagesPoint::new(languages.clone())))?;
+    registry.register(Arc::new(UiPoint::new(super::icons::POINT_ID, ui.clone(), super::icons::icon_theme)))?;
+    registry.register(Arc::new(super::run_detectors::RunDetectorsPoint::new(run_detectors.clone())))?;
+    registry.register(Arc::new(super::providers::ProvidersPoint::new(providers.clone())))?;
+    registry.register(Arc::new(UiPoint::new(super::providers::SECRETS_POINT, ui.clone(), super::providers::secret)))?;
+    use super::ui_points as p;
+    registry.register(Arc::new(UiPoint::new(p::MENUS, ui.clone(), p::menu)))?;
+    registry.register(Arc::new(UiPoint::new(p::KEYMAPS, ui.clone(), p::keymap)))?;
+    registry.register(Arc::new(UiPoint::new(p::STATUS_BAR, ui.clone(), p::status_item)))?;
+    registry.register(Arc::new(UiPoint::new(p::SETTINGS, ui.clone(), p::settings)))?;
+    registry.register(Arc::new(UiPoint::new(p::VIEWS, ui.clone(), p::view)))?;
+    registry.register(Arc::new(UiPoint::new(p::CUSTOM_EDITORS, ui.clone(), p::custom_editor)))?;
+    registry.register(Arc::new(UiPoint::new(p::FILE_ICONS, ui.clone(), p::file_icon)))?;
+    registry.register(Arc::new(UiPoint::new(p::FILE_TEMPLATES, ui.clone(), p::file_template)))?;
+    Ok(())
+}

crates/ide-host/src/plugins/providers.rs

@@ -0,0 +1,342 @@
+//! Editor providers of plugins: completion, inline
+//! completion, code actions, go to definition and gutter line markers, for
+//! the languages a plugin declares. The host calls only plugins whose
+//! declaration matches, so the others stay unloaded.
+//!
+//! ```toml
+//! [[contributes.providers]]
+//! kinds = ["definition", "line-markers"]
+//! languages = ["java", "xml"]        # editor language ids; "*" for any
+//! ```
+//!
+//! And `[[contributes.secrets]]`: secrets the user can store for the plugin
+//! (shown in Settings › Plugins), used only through `net` request headers.
+//!
+//! ```toml
+//! [[contributes.secrets]]
+//! name = "api-key"
+//! label = "API key"
+//! description = "Create one at https://example.com/keys"
+//! ```
+
+use ide_extension::{Disposable, ExtensionPoint, Package, Placement, Prepared, UiDecl, decode, validate_item_id};
+use parking_lot::RwLock;
+use serde::{Deserialize, Serialize};
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+pub const POINT_ID: &str = "providers";
+pub const SECRETS_POINT: &str = "secrets";
+
+/// What a plugin can provide in the editor.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize, specta::Type)]
+#[serde(rename_all = "kebab-case")]
+pub enum ProviderKind {
+    Completion,
+    InlineCompletion,
+    CodeActions,
+    Definition,
+    LineMarkers,
+}
+
+#[derive(Clone, Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
+struct Decl {
+    kinds: Vec<ProviderKind>,
+    languages: Vec<String>,
+}
+
+/// (sequence, plugin, kinds, languages) of one declaration.
+type Declared = (u64, String, Vec<ProviderKind>, Vec<String>);
+
+/// Provider declarations of enabled plugins.
+#[derive(Default)]
+pub struct Providers {
+    items: RwLock<Vec<Declared>>,
+    seq: AtomicU64,
+}
+
+impl Providers {
+    fn add(self: &Arc<Self>, plugin: String, decl: Decl) -> Disposable {
+        let seq = self.seq.fetch_add(1, Ordering::Relaxed);
+        self.items.write().push((seq, plugin, decl.kinds, decl.languages));
+        let weak = Arc::downgrade(self);
+        Disposable::new(move || {
+            if let Some(this) = weak.upgrade() {
+                this.items.write().retain(|(s, ..)| *s != seq);
+            }
+        })
+    }
+
+    /// Plugins providing `kind` for `language`, in declaration order.
+    pub fn plugins_for(&self, kind: ProviderKind, language: &str) -> Vec<String> {
+        let mut out: Vec<String> = Vec::new();
+        for (_, plugin, kinds, languages) in self.items.read().iter() {
+            if kinds.contains(&kind) && languages.iter().any(|l| l == "*" || l == language) && !out.contains(plugin) {
+                out.push(plugin.clone());
+            }
+        }
+        out
+    }
+
+    /// Whether any plugin provides `kind` (for any language).
+    pub fn any(&self, kind: ProviderKind) -> bool {
+        self.items.read().iter().any(|(_, _, kinds, _)| kinds.contains(&kind))
+    }
+}
+
+pub struct ProvidersPoint {
+    store: Arc<Providers>,
+}
+
+impl ProvidersPoint {
+    pub fn new(store: Arc<Providers>) -> Self {
+        Self { store }
+    }
+}
+
+impl ExtensionPoint for ProvidersPoint {
+    fn id(&self) -> &'static str {
+        POINT_ID
+    }
+
+    fn placement(&self) -> Placement {
+        Placement::Workspace
+    }
+
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+        let d: Decl = decode(POINT_ID, decl)?;
+        if pkg.manifest.wasm.is_none() {
+            return Err("contributes.providers: providers need code (`wasm`)".into());
+        }
+        if d.kinds.is_empty() || d.languages.is_empty() || d.languages.len() > 64 {
+            return Err("contributes.providers: give `kinds` and 1–64 `languages`".into());
+        }
+        for l in &d.languages {
+            if l != "*"
+                && (l.is_empty()
+                    || l.len() > 64
+                    || !l.chars().all(|c| c.is_ascii_alphanumeric() || "-_.+#".contains(c)))
+            {
+                return Err(format!("contributes.providers: invalid language id {l:?}"));
+            }
+        }
+        let label = format!(
+            "{} for {}",
+            d.kinds
+                .iter()
+                .map(|k| serde_json::to_value(k).ok().and_then(|v| v.as_str().map(str::to_owned)).unwrap_or_default())
+                .collect::<Vec<_>>()
+                .join(", "),
+            d.languages.join(", ")
+        );
+        let (store, plugin) = (self.store.clone(), pkg.id().to_owned());
+        Ok(Prepared::new(label, move || Ok(store.add(plugin, d))))
+    }
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct SecretDecl {
+    name: String,
+    label: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    description: Option<String>,
+}
+
+/// `[[contributes.secrets]]` (a UI point: Settings › Plugins lists them).
+pub(super) fn secret(_pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: SecretDecl = decode(SECRETS_POINT, decl)?;
+    validate_item_id(&d.name, "secret name")?;
+    if d.label.trim().is_empty() || d.label.len() > 128 || d.description.as_ref().is_some_and(|x| x.len() > 1024) {
+        return Err(format!("secret {:?}: `label` 1–128 bytes, `description` up to 1 KiB", d.name));
+    }
+    let json = serde_json::to_value(&d).map_err(|e| e.to_string())?;
+    Ok(UiDecl::new(d.name.clone(), d.label, json))
+}
+
+// ---- dispatch ---------------------------------------------------------------
+
+use super::{LoadedPlugin, PluginHost, PluginStatus};
+use ide_core::CancellationToken;
+use ide_plugin::{
+    ActorError, CallError, CodeAction, CompletionItem, InlineSuggestion, LineMarker, Location, Pending,
+    ProviderDocument, Runtime,
+};
+use std::sync::Weak;
+use std::time::{Duration, Instant};
+
+/// How long a superseded inline completion may take to return after its
+/// request was cancelled before it is interrupted.
+const CANCEL_GRACE: Duration = Duration::from_millis(250);
+
+static EDITOR_PROVIDERS: RwLock<Option<Weak<PluginHost>>> = RwLock::new(None);
+
+/// Makes `host`'s plugin providers part of completion, code actions, go to
+/// definition and inline completion (`None` removes them).
+pub fn set_editor_providers(host: Option<&Arc<PluginHost>>) {
+    *EDITOR_PROVIDERS.write() = host.map(Arc::downgrade);
+}
+
+/// The plugin host whose providers take part, when any declares `kind`.
+pub(crate) fn editor_providers(kind: ProviderKind) -> Option<Arc<PluginHost>> {
+    let host = EDITOR_PROVIDERS.read().as_ref()?.upgrade()?;
+    host.providers.any(kind).then_some(host)
+}
+
+impl PluginHost {
+    /// Usable plugins declaring `kind` for `language`.
+    fn provider_plugins(&self, kind: ProviderKind, language: &str) -> Vec<Arc<LoadedPlugin>> {
+        self.providers
+            .plugins_for(kind, language)
+            .into_iter()
+            .filter_map(|id| self.get(&id).ok())
+            .filter(|p| {
+                let m = p.meta.lock();
+                matches!(m.status, PluginStatus::Active | PluginStatus::Inactive) && m.pending.is_empty()
+            })
+            .collect()
+    }
+
+    /// Edit-path calls (soft / hard deadline) to every usable plugin that
+    /// declares `kind` for `language`, in plugin order, leaving out those that
+    /// failed or were late. Each plugin runs on its own thread, so the calls
+    /// run at the same time: the wait is the slowest plugin's, not the sum.
+    fn edit_calls<R: Send + 'static>(
+        &self,
+        kind: ProviderKind,
+        language: &str,
+        f: impl FnOnce(&mut Runtime, Duration) -> Result<R, CallError> + Clone + Send + 'static,
+    ) -> Vec<(Arc<LoadedPlugin>, R)> {
+        let (soft, hard) = (self.limits.edit_soft, self.limits.edit_hard);
+        let queued: Vec<_> = self
+            .provider_plugins(kind, language)
+            .into_iter()
+            .filter_map(|plugin| {
+                let (actor, activated) = self.ensure_active(&plugin, None).ok()?;
+                if activated {
+                    self.changed();
+                }
+                let f = f.clone();
+                let started = Instant::now();
+                let call = actor.submit(Some(soft), move |rt| f(rt, hard));
+                Some((plugin, actor, started, call))
+            })
+            .collect();
+        queued
+            .into_iter()
+            .filter_map(|(plugin, actor, started, call)| {
+                let result = call.and_then(Pending::wait);
+                self.finish_provider_call(&plugin, &actor, started, result).map(|r| (plugin, r))
+            })
+            .collect()
+    }
+
+    pub(super) fn finish_provider_call<R>(
+        &self,
+        plugin: &Arc<LoadedPlugin>,
+        actor: &Arc<ide_plugin::Actor>,
+        started: Instant,
+        result: Result<R, ActorError>,
+    ) -> Option<R> {
+        let elapsed = started.elapsed();
+        match result {
+            Ok(r) => {
+                self.record_call(plugin, elapsed, true, true);
+                Some(r)
+            }
+            Err(ActorError::SoftTimeout) => {
+                plugin.meta.lock().stats.slow_calls += 1;
+                None
+            }
+            Err(ActorError::Cancelled) => None,
+            Err(ActorError::Call(CallError::Guest(e))) => {
+                self.record_call(plugin, elapsed, !e.is_failure(), true);
+                tracing::debug!(plugin = %plugin.id(), "provider: {e}");
+                None
+            }
+            Err(ActorError::Call(CallError::Trap(_)) | ActorError::Stopped) => {
+                self.record_call(plugin, elapsed, false, false);
+                self.reap(plugin, actor, None);
+                None
+            }
+        }
+    }
+
+    pub fn provide_completion(
+        &self,
+        doc: &ProviderDocument,
+        at: ide_core::Pos,
+        trigger: Option<&str>,
+    ) -> Vec<(String, CompletionItem)> {
+        let (d, t) = (Arc::new(doc.clone()), trigger.map(str::to_owned));
+        self.edit_calls(ProviderKind::Completion, &doc.language, move |rt, timeout| {
+            rt.provide_completion(&d, at, t.as_deref(), timeout)
+        })
+        .into_iter()
+        .flat_map(|(p, items)| items.into_iter().map(move |i| (p.id().to_owned(), i)))
+        .collect()
+    }
+
+    pub fn provide_code_actions(
+        &self,
+        doc: &ProviderDocument,
+        selection: ide_core::Range,
+    ) -> Vec<(String, CodeAction)> {
+        let d = Arc::new(doc.clone());
+        self.edit_calls(ProviderKind::CodeActions, &doc.language, move |rt, timeout| {
+            rt.provide_code_actions(&d, selection, timeout)
+        })
+        .into_iter()
+        .flat_map(|(p, actions)| actions.into_iter().map(move |a| (p.id().to_owned(), a)))
+        .collect()
+    }
+
+    pub fn provide_definition(&self, doc: &ProviderDocument, at: ide_core::Pos) -> Vec<Location> {
+        let d = Arc::new(doc.clone());
+        self.edit_calls(ProviderKind::Definition, &doc.language, move |rt, timeout| {
+            rt.provide_definition(&d, at, timeout)
+        })
+        .into_iter()
+        .flat_map(|(_, locations)| locations)
+        .collect()
+    }
+
+    pub fn provide_line_markers(&self, doc: &ProviderDocument) -> Vec<(String, LineMarker)> {
+        let d = Arc::new(doc.clone());
+        self.edit_calls(ProviderKind::LineMarkers, &doc.language, move |rt, timeout| {
+            rt.provide_line_markers(&d, timeout)
+        })
+        .into_iter()
+        .flat_map(|(p, markers)| markers.into_iter().map(move |m| (p.id().to_owned(), m)))
+        .collect()
+    }
+
+    /// Ghost text from the first plugin that has some. Not bound by the
+    /// edit-path soft deadline (it may need the network) but by `cancel`:
+    /// the editor cancels a request as soon as the user types on.
+    pub fn provide_inline_completion(
+        &self,
+        doc: &ProviderDocument,
+        at: ide_core::Pos,
+        cancel: &CancellationToken,
+    ) -> Option<(String, InlineSuggestion)> {
+        for p in self.provider_plugins(ProviderKind::InlineCompletion, &doc.language) {
+            if cancel.is_cancelled() {
+                return None;
+            }
+            let Ok((actor, activated)) = self.ensure_active(&p, None) else { continue };
+            if activated {
+                self.changed();
+            }
+            let (d, timeout) = (doc.clone(), self.limits.timeout);
+            let started = Instant::now();
+            let result =
+                actor.call_cancellable(cancel, CANCEL_GRACE, move |rt| rt.provide_inline_completion(&d, at, timeout));
+            if let Some(Some(s)) = self.finish_provider_call(&p, &actor, started, result) {
+                return Some((p.id().to_owned(), s));
+            }
+        }
+        None
+    }
+}

crates/ide-host/src/plugins/remote.rs

@@ -0,0 +1,222 @@
+//! Plugin languages of a remote project: `Workspace` contributions take effect where the project is, so the
+//! desktop pushes its plugins' language definitions to `openidea-server`
+//! (`plugin_sync_languages`) together with the `process:` programs the user
+//! granted. The server resolves each granted program on its own `PATH`, pins
+//! the file (path + hash, kept in `plugin-pins.json`) the first time and
+//! starts only that file afterwards; a program missing from a sync is revoked.
+//! Revoking and granting again on the desktop re-pins a replaced program.
+
+use ide_extension::Capability;
+use ide_extension::ledger::{self, BinaryGrant};
+use ide_language::plugin_point::{PluginLanguages, validate_definition};
+use ide_language::{LanguageConfig, ProgramPin};
+use parking_lot::Mutex;
+use serde::{Deserialize, Serialize};
+use std::collections::BTreeMap;
+use std::path::PathBuf;
+use std::sync::Arc;
+
+pub const PINS_FILE: &str = "plugin-pins.json";
+/// The server command the desktop calls.
+pub const SYNC_COMMAND: &str = "plugin_sync_languages";
+
+/// One plugin language as the desktop sends it.
+#[derive(Clone, Debug, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct RemoteLanguage {
+    pub plugin: String,
+    pub language: LanguageConfig,
+    /// Program names of the plugin's granted `process:` capabilities.
+    #[serde(default)]
+    pub granted: Vec<String>,
+}
+
+/// What the server made of a sync.
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "camelCase")]
+pub struct SyncReport {
+    pub languages: usize,
+    /// `plugin: program` → the file it starts.
+    pub pinned: BTreeMap<String, PathBuf>,
+    /// Granted programs not found on this machine's `PATH`.
+    pub unresolved: Vec<String>,
+    /// Definitions that failed validation (not applied).
+    pub rejected: Vec<String>,
+}
+
+#[derive(Default, Serialize, Deserialize)]
+struct PinsFile {
+    /// `plugin\nprocess:program` → the approved file.
+    #[serde(default)]
+    pins: BTreeMap<String, BinaryGrant>,
+}
+
+type PathVar = Arc<dyn Fn() -> Option<std::ffi::OsString> + Send + Sync>;
+
+/// The server's side: an overlay for its language registry, filled by syncs.
+pub struct RemotePluginLanguages {
+    store: Arc<PluginLanguages>,
+    pins: Arc<Mutex<BTreeMap<String, BinaryGrant>>>,
+    file: Option<PathBuf>,
+    applied: Mutex<Vec<ide_extension::Disposable>>,
+    path_var: PathVar,
+}
+
+fn key(plugin: &str, cap: &Capability) -> String {
+    format!("{plugin}\n{cap}")
+}
+
+impl RemotePluginLanguages {
+    /// Pins persist in `data_dir` (none: in memory, for tests).
+    pub fn new(data_dir: Option<&std::path::Path>) -> Arc<Self> {
+        Self::with_path(data_dir, Arc::new(|| std::env::var_os("PATH")))
+    }
+
+    pub fn with_path(data_dir: Option<&std::path::Path>, path_var: PathVar) -> Arc<Self> {
+        let file = data_dir.map(|d| d.join(PINS_FILE));
+        let saved: PinsFile = file
+            .as_ref()
+            .and_then(|f| std::fs::read_to_string(f).ok())
+            .and_then(|s| serde_json::from_str(&s).ok())
+            .unwrap_or_default();
+        let pins = Arc::new(Mutex::new(saved.pins));
+        let store = PluginLanguages::new();
+        let policy_pins = pins.clone();
+        store.set_process_policy(Arc::new(move |plugin, cap| {
+            policy_pins.lock().get(&key(plugin, cap)).map(|b| ProgramPin { path: b.path.clone(), hash: b.hash.clone() })
+        }));
+        Arc::new(Self { store, pins, file, applied: Mutex::default(), path_var })
+    }
+
+    /// For [`ide_language::LanguageRegistry::attach_plugins`].
+    pub fn store(&self) -> &Arc<PluginLanguages> {
+        &self.store
+    }
+
+    /// Replaces every plugin language with `languages`.
+    pub fn sync(&self, languages: Vec<RemoteLanguage>) -> SyncReport {
+        let mut report = SyncReport::default();
+        let mut wanted: BTreeMap<String, (String, Capability)> = BTreeMap::new();
+        let mut accepted = Vec::new();
+        for l in languages {
+            if let Err(e) = validate_definition(&l.language) {
+                report.rejected.push(format!("{} ({}): {e}", l.language.id, l.plugin));
+                continue;
+            }
+            for program in &l.granted {
+                let cap = Capability::Process(program.clone());
+                // Only programs the definition starts: a grant is not a licence for anything else.
+                if ide_language::plugin_point::required_capabilities(&l.language).contains(&cap) {
+                    wanted.insert(key(&l.plugin, &cap), (program.clone(), cap));
+                }
+            }
+            accepted.push(l);
+        }
+        {
+            let mut pins = self.pins.lock();
+            pins.retain(|k, _| wanted.contains_key(k));
+            for (k, (program, _)) in &wanted {
+                if pins.contains_key(k) {
+                    continue;
+                }
+                let resolved = ledger::resolve_program(program, (self.path_var)().as_deref()).and_then(|path| {
+                    ledger::file_hash(&path).map(|hash| BinaryGrant { path, hash }).map_err(|e| e.to_string())
+                });
+                match resolved {
+                    Ok(bin) => {
+                        pins.insert(k.clone(), bin);
+                    }
+                    Err(e) => {
+                        tracing::info!("process:{program}: {e}");
+                        report.unresolved.push(program.clone());
+                    }
+                }
+            }
+            for (k, bin) in pins.iter() {
+                report.pinned.insert(k.replace("\nprocess:", ": "), bin.path.clone());
+            }
+            self.save(&pins);
+        }
+        let mut applied = self.applied.lock();
+        applied.clear(); // disposes the previous sync's languages
+        for l in accepted {
+            applied.push(self.store.add(l.plugin, l.language));
+        }
+        report.languages = applied.len();
+        self.store.invalidate();
+        report
+    }
+
+    fn save(&self, pins: &BTreeMap<String, BinaryGrant>) {
+        let Some(file) = &self.file else { return };
+        let json = serde_json::to_string_pretty(&PinsFile { pins: pins.clone() }).unwrap_or_default();
+        let tmp = file.with_extension("json.tmp");
+        if let Err(e) = std::fs::write(&tmp, json).and_then(|()| std::fs::rename(&tmp, file)) {
+            tracing::warn!("saving {}: {e}", file.display());
+        }
+    }
+}
+
+#[cfg(all(test, unix))]
+mod tests {
+    use super::*;
+    use ide_core::LanguageId;
+    use ide_language::LanguageRegistry;
+    use std::os::unix::fs::PermissionsExt;
+
+    fn toy(granted: &[&str]) -> RemoteLanguage {
+        let language = ide_language::plugin_point::parse_definition(
+            "id = \"toy\"\nname = \"Toy\"\nextensions = [\"toy\"]\n\
+             [[language-servers]]\nname = \"toylsp\"\ncommand = \"toylsp\"\n",
+        )
+        .unwrap();
+        RemoteLanguage {
+            plugin: "acme.toy".into(),
+            language,
+            granted: granted.iter().map(|s| (*s).to_owned()).collect(),
+        }
+    }
+
+    #[test]
+    fn syncs_languages_and_pins_granted_programs_on_this_machine() {
+        let tmp = tempfile::tempdir().unwrap();
+        let bin = tmp.path().join("bin");
+        std::fs::create_dir(&bin).unwrap();
+        std::fs::write(bin.join("toylsp"), "#!/bin/sh\n").unwrap();
+        std::fs::set_permissions(bin.join("toylsp"), std::fs::Permissions::from_mode(0o755)).unwrap();
+        let path = bin.clone().into_os_string();
+        let remote = RemotePluginLanguages::with_path(Some(tmp.path()), Arc::new(move || Some(path.clone())));
+        let registry = LanguageRegistry::load(None).unwrap();
+        registry.attach_plugins(remote.store().clone());
+        let project = registry.fork();
+        let id = LanguageId::new("toy");
+
+        // Not granted: the language, no server.
+        let report = remote.sync(vec![toy(&[])]);
+        assert_eq!(report.languages, 1);
+        assert_eq!(project.detect(std::path::Path::new("/r/a.toy"), None), id);
+        assert!(project.get(&id).unwrap().language_servers.is_empty());
+
+        // Granted: resolved here and pinned; persisted.
+        let report = remote.sync(vec![toy(&["toylsp", "rm"])]);
+        assert_eq!(report.pinned.len(), 1, "only programs the definition starts: {report:?}");
+        let pin = project.get(&id).unwrap().language_servers[0].pinned.clone().unwrap();
+        assert!(pin.verify().is_ok());
+        assert!(tmp.path().join(PINS_FILE).is_file());
+
+        // Replaced: refused at start until revoked and granted again.
+        std::fs::write(bin.join("toylsp"), "#!/bin/sh\necho x\n").unwrap();
+        remote.sync(vec![toy(&["toylsp"])]);
+        assert!(project.get(&id).unwrap().language_servers[0].pinned.as_ref().unwrap().verify().is_err());
+        remote.sync(vec![toy(&[])]);
+        remote.sync(vec![toy(&["toylsp"])]);
+        assert!(project.get(&id).unwrap().language_servers[0].pinned.as_ref().unwrap().verify().is_ok());
+
+        // Missing programs are reported; invalid definitions rejected; empty sync removes all.
+        let mut bad = toy(&[]);
+        bad.language.id = LanguageId::new("a b");
+        let report = remote.sync(vec![bad]);
+        assert_eq!(report.rejected.len(), 1);
+        assert_eq!(project.detect(std::path::Path::new("/r/a.toy"), None), LanguageId::plain_text());
+    }
+}

crates/ide-host/src/plugins/remote_host.rs

@@ -0,0 +1,504 @@
+//! Code plugins of remote projects:
+//! Wasm runs where the project is, so `openidea-server` hosts the desktop's
+//! code plugins and they read, search, run processes and publish diagnostics
+//! on the remote machine.
+//!
+//! The desktop stays the authority over what is installed and granted. It
+//! pushes its live code plugins with [`SYNC_PACKAGES`]: first their digests
+//! and grants, then the files of those the server doesn't have (one package
+//! per request); a package missing from a sync is uninstalled. The server
+//! installs them under `<data>/remote-plugins` and records the desktop's
+//! grants (a `process:` grant is pinned to the program on this machine's
+//! `PATH`).
+//!
+//! The commands a window needs at run time (`plugin_run_command`,
+//! `plugin_post_events`, `plugin_event_kinds`, `plugin_status_items`,
+//! `plugin_cancel_task`, `plugin_set_active_file`, `plugin_line_markers`,
+//! `plugin_view_render`, `plugin_view_event`)
+//! carry the desktop commands' names and arguments, so a remote window's UI
+//! routes them here unchanged. Plugin results come back as `plugin`
+//! notifications ([`PluginEventMessage`]); secrets stay in the desktop's
+//! keychain and are asked for with a `plugin_secret` request
+//! ([`SecretRequest`]) when a request header needs one (rule 4).
+
+use super::{
+    Consent, HostWorkspace, PluginEditor, PluginEvent, PluginHost, PluginSource, PluginStatusItem, SecretStore,
+};
+use crate::rpc::Dispatcher;
+use base64::Engine as _;
+use ide_core::{IdeError, IdeResult};
+use ide_extension::{MANIFEST_FILE, ledger};
+use ide_jsonrpc::Peer;
+use ide_plugin::{Invocation, Limits};
+use parking_lot::Mutex;
+use serde::{Deserialize, Serialize};
+use std::collections::{BTreeMap, BTreeSet};
+use std::path::{Component, Path, PathBuf};
+use std::sync::{Arc, OnceLock, Weak};
+use std::time::Duration;
+
+/// The server command the desktop calls with its packages.
+pub const SYNC_PACKAGES: &str = "plugin_sync_packages";
+/// Server → client notification carrying a [`PluginEventMessage`].
+pub const EVENT_NOTIFICATION: &str = "plugin";
+/// Server → client request ([`SecretRequest`] → `Option<String>`).
+pub const SECRET_REQUEST: &str = "plugin_secret";
+/// Under the server's data directory.
+pub const PLUGINS_DIR: &str = "remote-plugins";
+const INCOMING_DIR: &str = "remote-plugins.incoming";
+const SECRET_TIMEOUT: Duration = Duration::from_secs(10);
+const EVENT_FLUSH: Duration = Duration::from_millis(250);
+const TICKS_PER_SUPERVISION: u32 = 20;
+
+/// One live code plugin of the desktop.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct RemotePackage {
+    pub id: String,
+    /// [`package_digest`] of the package.
+    pub digest: String,
+    /// Capabilities the user granted on the desktop.
+    pub granted: Vec<String>,
+}
+
+/// One file of a package (`path` relative to the package, `data` base64).
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct PackageFile {
+    pub path: String,
+    pub data: String,
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct PackageSyncReport {
+    /// Packages the server needs the files of (send them in another sync).
+    pub missing: Vec<String>,
+    pub installed: Vec<String>,
+    pub removed: Vec<String>,
+    /// `id: reason`.
+    pub failed: Vec<String>,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct PluginEventMessage {
+    /// The window that invoked the plugin (`None`: every window of the connection).
+    pub window: Option<String>,
+    pub event: PluginEvent,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct SecretRequest {
+    pub plugin: String,
+    pub name: String,
+}
+
+/// Identifies a package's content: the manifest, the files its declarations
+/// reference and the component.
+pub fn package_digest(dir: &Path, files: &[PathBuf]) -> IdeResult<String> {
+    let mut all = files.to_vec();
+    all.push(PathBuf::from(MANIFEST_FILE));
+    Ok(ledger::package_hash(dir, &all)?)
+}
+
+/// Whether a plugin event means something to a remote window (the desktop
+/// owns the plugin list, themes and consent).
+pub fn forwarded(event: &PluginEvent) -> bool {
+    matches!(
+        event,
+        PluginEvent::Notification { .. }
+            | PluginEvent::StatusItemChanged { .. }
+            | PluginEvent::TaskStarted { .. }
+            | PluginEvent::TaskProgress { .. }
+            | PluginEvent::TaskEnded { .. }
+            | PluginEvent::SubscriptionsChanged
+            | PluginEvent::ViewChanged { .. }
+            | PluginEvent::ViewMessage { .. }
+            | PluginEvent::OpenTerminal { .. }
+    )
+}
+
+// ---- desktop side -----------------------------------------------------------
+
+impl PluginHost {
+    fn package_files(&self, plugin: &super::LoadedPlugin) -> IdeResult<Vec<PathBuf>> {
+        let set = self.registry.prepare(&plugin.pkg).map_err(IdeError::invalid)?;
+        Ok(set.files.into_iter().chain(plugin.manifest().wasm.clone()).collect())
+    }
+
+    /// The live code plugins (installed or linked) for a remote project's server.
+    pub fn remote_packages(&self) -> Vec<RemotePackage> {
+        let plugins: Vec<_> = self.plugins.read().values().cloned().collect();
+        plugins
+            .iter()
+            .filter(|p| p.dev_root.is_none() && !p.invalid && p.manifest().wasm.is_some())
+            .filter(|p| matches!(p.status(), super::PluginStatus::Active | super::PluginStatus::Inactive))
+            .filter_map(|p| {
+                let files = self.package_files(p).ok()?;
+                let digest = package_digest(p.dir(), &files).ok()?;
+                let granted = p.meta.lock().granted.iter().map(ToString::to_string).collect();
+                Some(RemotePackage { id: p.id().to_owned(), digest, granted })
+            })
+            .collect()
+    }
+
+    /// The files of a package for [`SYNC_PACKAGES`], the manifest first.
+    pub fn remote_package_files(&self, id: &str) -> IdeResult<Vec<PackageFile>> {
+        let plugin = self.get(id)?;
+        let files = self.package_files(&plugin)?;
+        std::iter::once(PathBuf::from(MANIFEST_FILE))
+            .chain(files)
+            .map(|rel| {
+                let bytes = std::fs::read(plugin.dir().join(&rel))?;
+                let path = rel.to_str().ok_or_else(|| IdeError::invalid("non UTF-8 file name"))?.replace('\\', "/");
+                Ok(PackageFile { path, data: base64::engine::general_purpose::STANDARD.encode(bytes) })
+            })
+            .collect()
+    }
+
+    /// A secret a plugin declares, for its remote instance (`plugin_secret`).
+    pub fn declared_secret(&self, id: &str, name: &str) -> Option<String> {
+        let plugin = self.get(id).ok()?;
+        if !self.ui.items(super::providers::SECRETS_POINT, Some(plugin.id())).iter().any(|s| s.key == name) {
+            return None;
+        }
+        let store = self.shared.secrets.read().clone();
+        store.get(plugin.id(), name)
+    }
+}
+
+// ---- server side ------------------------------------------------------------
+
+/// The plugin host of `openidea-server`.
+pub struct RemotePlugins {
+    host: Arc<PluginHost>,
+    incoming: PathBuf,
+    sync: Mutex<()>,
+}
+
+/// Secrets from the desktop's keychain, asked for when used.
+struct ClientSecrets {
+    peer: Arc<OnceLock<Peer>>,
+    runtime: tokio::runtime::Handle,
+}
+
+impl SecretStore for ClientSecrets {
+    fn get(&self, plugin: &str, name: &str) -> Option<String> {
+        let peer = self.peer.get()?.clone();
+        let request = SecretRequest { plugin: plugin.to_owned(), name: name.to_owned() };
+        let ask = async move {
+            tokio::time::timeout(SECRET_TIMEOUT, peer.request::<_, Option<String>>(SECRET_REQUEST, request, None)).await
+        };
+        // Plugin threads block on the runtime; a runtime worker (a host
+        // command asking) must leave its thread to the other tasks first.
+        let answer = if tokio::runtime::Handle::try_current().is_ok() {
+            tokio::task::block_in_place(|| self.runtime.block_on(ask))
+        } else {
+            self.runtime.block_on(ask)
+        };
+        match answer {
+            Ok(Ok(value)) => value,
+            Ok(Err(e)) => {
+                tracing::warn!("plugin secret {plugin}/{name}: {e}");
+                None
+            }
+            Err(_) => None,
+        }
+    }
+
+    fn set(&self, _: &str, _: &str, _: Option<&str>) -> Result<(), String> {
+        Err("secrets are stored on the desktop".into())
+    }
+}
+
+impl RemotePlugins {
+    /// Creates the host over `<data_dir>/remote-plugins`, loads what earlier
+    /// sessions installed and starts event delivery and supervision.
+    pub fn start(data_dir: &Path, projects: &Arc<crate::Host>, peer: Arc<OnceLock<Peer>>) -> IdeResult<Arc<Self>> {
+        let sink_peer = peer.clone();
+        let sink = move |client: Option<&str>, event: PluginEvent| {
+            if forwarded(&event)
+                && let Some(p) = sink_peer.get()
+            {
+                let _ = p.notify(EVENT_NOTIFICATION, PluginEventMessage { window: client.map(str::to_owned), event });
+            }
+        };
+        let host = Arc::new(PluginHost::new(data_dir.join(PLUGINS_DIR), Arc::new(sink), Limits::default())?);
+        host.set_workspace(Some(Arc::new(HostWorkspace(Arc::downgrade(projects)))));
+        host.set_secret_store(Arc::new(ClientSecrets { peer, runtime: projects.runtime.clone() }));
+        let trust = Arc::downgrade(projects);
+        host.set_project_policy(Arc::new(move |root| {
+            trust.upgrade().is_some_and(|h| h.trust.trusted(root).unwrap_or(false))
+        }));
+        super::set_editor_providers(Some(&host));
+        ide_language::set_external_syntax(Some(host.syntax_provider()));
+        ide_run::set_external_detection(Some(host.run_detection()));
+        host.load_all();
+        host.startup_finished();
+        spawn_supervision(Arc::downgrade(&host))?;
+        Ok(Arc::new(Self { host, incoming: data_dir.join(INCOMING_DIR), sync: Mutex::new(()) }))
+    }
+
+    pub fn host(&self) -> &Arc<PluginHost> {
+        &self.host
+    }
+
+    /// Makes the installed packages match `packages`: uninstalls the others,
+    /// follows changed grants, installs those with `files` and reports the
+    /// rest as missing.
+    pub fn sync(
+        &self,
+        packages: Vec<RemotePackage>,
+        mut files: BTreeMap<String, Vec<PackageFile>>,
+    ) -> PackageSyncReport {
+        let _guard = self.sync.lock();
+        let mut report = PackageSyncReport::default();
+        let wanted: BTreeSet<&str> = packages.iter().map(|p| p.id.as_str()).collect();
+        let installed: Vec<String> = self
+            .host
+            .plugins
+            .read()
+            .values()
+            .filter(|p| p.source == PluginSource::Installed)
+            .map(|p| p.id().to_owned())
+            .collect();
+        for id in installed.iter().filter(|id| !wanted.contains(id.as_str())) {
+            match self.host.uninstall(id) {
+                Ok(()) => report.removed.push(id.clone()),
+                Err(e) => report.failed.push(format!("{id}: {e}")),
+            }
+        }
+        for pkg in packages {
+            if !valid_id(&pkg.id) {
+                report.failed.push(format!("{}: invalid plugin id", pkg.id));
+                continue;
+            }
+            let consent = Consent { optional: pkg.granted.clone() };
+            if self.current_digest(&pkg.id).as_deref() == Some(pkg.digest.as_str()) {
+                if let Err(e) = self.follow_grants(&pkg, &consent) {
+                    report.failed.push(format!("{}: {e}", pkg.id));
+                }
+                continue;
+            }
+            match files.remove(&pkg.id) {
+                None => report.missing.push(pkg.id),
+                Some(list) => match self.install(&pkg, list, &consent) {
+                    Ok(()) => report.installed.push(pkg.id),
+                    Err(e) => report.failed.push(format!("{}: {}", pkg.id, e.message)),
+                },
+            }
+        }
+        report
+    }
+
+    fn current_digest(&self, id: &str) -> Option<String> {
+        let plugin = self.host.plugins.read().get(id).cloned()?;
+        if plugin.source != PluginSource::Installed || plugin.invalid {
+            return None;
+        }
+        let files = self.host.package_files(&plugin).ok()?;
+        package_digest(plugin.dir(), &files).ok()
+    }
+
+    fn follow_grants(&self, pkg: &RemotePackage, consent: &Consent) -> IdeResult<()> {
+        let info = self.host.info_of(&pkg.id)?;
+        let have: BTreeSet<&str> = info.capabilities.iter().filter(|c| c.granted).map(|c| c.id.as_str()).collect();
+        let want: BTreeSet<&str> = pkg.granted.iter().map(String::as_str).collect();
+        if have != want || info.status == super::PluginStatus::NeedsConsent {
+            self.host.grant(&pkg.id, consent)?;
+        }
+        Ok(())
+    }
+
+    fn install(&self, pkg: &RemotePackage, files: Vec<PackageFile>, consent: &Consent) -> IdeResult<()> {
+        let dir = self.incoming.join(&pkg.id);
+        let _ = std::fs::remove_dir_all(&dir);
+        let result = (|| {
+            let mut rels = Vec::new();
+            for f in files {
+                let rel = safe_relative(&f.path)?;
+                let bytes = base64::engine::general_purpose::STANDARD
+                    .decode(f.data.as_bytes())
+                    .map_err(|e| IdeError::invalid(format!("{}: {e}", f.path)))?;
+                let to = dir.join(&rel);
+                if let Some(parent) = to.parent() {
+                    std::fs::create_dir_all(parent)?;
+                }
+                std::fs::write(&to, bytes)?;
+                if rel != Path::new(MANIFEST_FILE) {
+                    rels.push(rel);
+                }
+            }
+            if package_digest(&dir, &rels)? != pkg.digest {
+                return Err(IdeError::invalid("the package arrived incomplete or changed"));
+            }
+            let info = self.host.install_from_dir(&dir, consent)?;
+            if info.id != pkg.id {
+                let _ = self.host.uninstall(&info.id);
+                return Err(IdeError::invalid(format!("the package is plugin {:?}", info.id)));
+            }
+            Ok(())
+        })();
+        let _ = std::fs::remove_dir_all(&dir);
+        result
+    }
+
+    /// The run-time commands of remote windows plus [`SYNC_PACKAGES`].
+    pub fn register(self: &Arc<Self>, d: &mut Dispatcher) {
+        let this = self.clone();
+        d.add(SYNC_PACKAGES, move |c| {
+            let this = this.clone();
+            async move {
+                let packages: Vec<RemotePackage> = c.arg("packages")?;
+                let files: Option<BTreeMap<String, Vec<PackageFile>>> = c.arg("files")?;
+                blocking(move || Ok(this.sync(packages, files.unwrap_or_default()))).await
+            }
+        });
+        let host = Arc::downgrade(&self.host);
+        let h = host.clone();
+        d.add("plugin_run_command", move |c| {
+            let h = h.clone();
+            async move {
+                let host = alive(&h)?;
+                let plugin_id: String = c.arg("pluginId")?;
+                let command_id: String = c.arg("commandId")?;
+                let arg: Option<String> = c.arg("arg")?;
+                let editor: Option<PluginEditor> = c.arg("editor")?;
+                let invocation = Invocation {
+                    client: Some(c.window.clone()),
+                    workspace_root: c.host.project(&c.window).ok().map(|p| p.root.clone()),
+                    editor: editor.map(PluginEditor::context),
+                };
+                blocking(move || host.run_command(&plugin_id, &command_id, arg.as_deref(), invocation)).await
+            }
+        });
+        let h = host.clone();
+        d.add("plugin_post_events", move |c| {
+            let h = h.clone();
+            async move {
+                alive(&h)?.post_events(Some(&c.window), c.arg("events")?);
+                Ok(())
+            }
+        });
+        let h = host.clone();
+        d.add("plugin_event_kinds", move |_| {
+            let h = h.clone();
+            async move { Ok(alive(&h)?.event_kinds().into_iter().collect::<Vec<_>>()) }
+        });
+        let h = host.clone();
+        d.add("plugin_status_items", move |_| {
+            let h = h.clone();
+            async move {
+                Ok(alive(&h)?
+                    .status_items()
+                    .into_iter()
+                    .map(|(plugin_id, id, item)| PluginStatusItem { plugin_id, id, item })
+                    .collect::<Vec<_>>())
+            }
+        });
+        let h = host.clone();
+        d.add("plugin_cancel_task", move |c| {
+            let h = h.clone();
+            async move { Ok(alive(&h)?.cancel_task(&c.arg::<String>("taskId")?)) }
+        });
+        let h = host.clone();
+        d.add("plugin_set_active_file", move |c| {
+            let h = h.clone();
+            async move {
+                alive(&h)?.set_active_file(&c.window, c.arg("path")?);
+                Ok(())
+            }
+        });
+        let h = host.clone();
+        d.add("plugin_view_render", move |c| {
+            let h = h.clone();
+            async move {
+                let plugins = alive(&h)?;
+                super::views::render(
+                    &c.host,
+                    plugins,
+                    &c.window,
+                    c.arg("pluginId")?,
+                    c.arg("view")?,
+                    c.arg("viewport")?,
+                    c.arg("doc")?,
+                    c.arg("editor")?,
+                )
+                .await
+            }
+        });
+        let h = host.clone();
+        d.add("plugin_view_event", move |c| {
+            let h = h.clone();
+            async move {
+                let plugins = alive(&h)?;
+                super::views::event(
+                    &c.host,
+                    plugins,
+                    &c.window,
+                    c.arg("pluginId")?,
+                    c.arg("view")?,
+                    c.arg("event")?,
+                    c.arg("doc")?,
+                    c.arg("editor")?,
+                )
+                .await
+            }
+        });
+        d.add("plugin_line_markers", |c| async move {
+            crate::ops::lsp::plugin_line_markers(&c.host, &c.window, c.arg("doc")?).await
+        });
+    }
+}
+
+fn alive(host: &Weak<PluginHost>) -> IdeResult<Arc<PluginHost>> {
+    host.upgrade().ok_or_else(|| IdeError::unavailable("the plugin host has shut down"))
+}
+
+async fn blocking<T: Send + 'static>(f: impl FnOnce() -> IdeResult<T> + Send + 'static) -> IdeResult<T> {
+    tokio::task::spawn_blocking(f).await.map_err(|e| IdeError::internal(e.to_string()))?
+}
+
+fn spawn_supervision(host: Weak<PluginHost>) -> IdeResult<()> {
+    std::thread::Builder::new().name("remote-plugins".into()).spawn(move || {
+        for n in 1u32.. {
+            std::thread::sleep(EVENT_FLUSH);
+            let Some(host) = host.upgrade() else { return };
+            host.flush_events();
+            if n % TICKS_PER_SUPERVISION == 0 {
+                host.tick();
+            }
+        }
+    })?;
+    Ok(())
+}
+
+fn valid_id(id: &str) -> bool {
+    !id.is_empty()
+        && id.len() <= 128
+        && !id.starts_with('.')
+        && id.chars().all(|c| c.is_ascii_alphanumeric() || "-_.".contains(c))
+}
+
+/// `path` as a relative path inside a package (no `..`, no root).
+fn safe_relative(path: &str) -> IdeResult<PathBuf> {
+    let p = Path::new(path);
+    if path.is_empty() || !p.components().all(|c| matches!(c, Component::Normal(_))) {
+        return Err(IdeError::invalid(format!("invalid file path {path:?} in package")));
+    }
+    Ok(p.to_path_buf())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn package_paths_stay_inside_the_package() {
+        assert!(safe_relative("dist/plugin.wasm").is_ok());
+        for bad in ["", "../x", "/etc/passwd", "a/../../b", "./x"] {
+            assert!(safe_relative(bad).is_err(), "{bad}");
+        }
+        assert!(valid_id("ai-completion"));
+        assert!(!valid_id("../x") && !valid_id(".data") && !valid_id(""));
+    }
+}

crates/ide-host/src/plugins/run_detectors.rs

@@ -0,0 +1,167 @@
+//! The `runDetectors` extension point: run configurations a plugin offers in
+//! projects that contain a marker file.
+//!
+//! ```toml
+//! [[contributes.runDetectors]]
+//! id = "forge-test"
+//! name = "forge test"
+//! files = ["foundry.toml"]       # any of these at the project root
+//! command = "forge"
+//! args = ["test"]
+//! test = true                    # results go to the test tree
+//! ```
+//!
+//! The command is a `process:` capability like a language server's: the
+//! configuration is offered only while it is granted, and starts the approved
+//! file (checked right before it starts).
+
+use ide_extension::{
+    Capability, Disposable, ExtensionPoint, Package, Placement, Prepared, check_relative, decode, validate_item_id,
+};
+use ide_language::ProgramPin;
+use ide_run::{EXTERNAL_PREFIX, ExternalDetection, RunConfig};
+use parking_lot::RwLock;
+use serde::Deserialize;
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+pub const POINT_ID: &str = "runDetectors";
+const MAX_FILES: usize = 16;
+const MAX_ARGS: usize = 64;
+
+#[derive(Clone, Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct Detector {
+    pub id: String,
+    pub name: String,
+    pub files: Vec<PathBuf>,
+    pub command: String,
+    #[serde(default)]
+    pub args: Vec<String>,
+    #[serde(default)]
+    pub test: bool,
+}
+
+/// Detectors of enabled plugins.
+#[derive(Default)]
+pub struct RunDetectors {
+    items: RwLock<Vec<(u64, String, Detector)>>,
+    seq: AtomicU64,
+}
+
+impl RunDetectors {
+    fn add(self: &Arc<Self>, plugin: String, detector: Detector) -> Disposable {
+        let seq = self.seq.fetch_add(1, Ordering::Relaxed);
+        self.items.write().push((seq, plugin, detector));
+        let weak = Arc::downgrade(self);
+        Disposable::new(move || {
+            if let Some(this) = weak.upgrade() {
+                this.items.write().retain(|(s, _, _)| *s != seq);
+            }
+        })
+    }
+}
+
+pub struct RunDetectorsPoint {
+    store: Arc<RunDetectors>,
+}
+
+impl RunDetectorsPoint {
+    pub fn new(store: Arc<RunDetectors>) -> Self {
+        Self { store }
+    }
+}
+
+impl ExtensionPoint for RunDetectorsPoint {
+    fn id(&self) -> &'static str {
+        POINT_ID
+    }
+
+    fn placement(&self) -> Placement {
+        Placement::Workspace
+    }
+
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+        let d: Detector = decode(POINT_ID, decl)?;
+        validate_item_id(&d.id, "run detector id")?;
+        if d.name.trim().is_empty() || d.name.len() > 128 {
+            return Err(format!("run detector {:?}: `name` must be 1–128 bytes", d.id));
+        }
+        if d.files.is_empty() || d.files.len() > MAX_FILES {
+            return Err(format!("run detector {:?}: give 1–{MAX_FILES} marker `files`", d.id));
+        }
+        for f in &d.files {
+            check_relative(f, "files")?;
+        }
+        let program = d.command.trim();
+        if program.is_empty() || program.contains(char::is_whitespace) {
+            return Err(format!("run detector {:?}: `command` is one program name (arguments go in `args`)", d.id));
+        }
+        if d.args.len() > MAX_ARGS {
+            return Err(format!("run detector {:?}: at most {MAX_ARGS} arguments", d.id));
+        }
+        let cap = Capability::Process(program.to_owned());
+        let (store, plugin, label) = (self.store.clone(), pkg.id().to_owned(), d.name.clone());
+        let key = d.id.clone();
+        Ok(Prepared::new(label, move || Ok(store.add(plugin, d))).key(key).capability(cap))
+    }
+}
+
+type Pins = Arc<RwLock<HashMap<(String, String), ProgramPin>>>;
+
+/// [`ExternalDetection`] over the detectors and the approved programs.
+pub struct PluginRunDetection {
+    pub(crate) store: Arc<RunDetectors>,
+    pub(crate) pins: Pins,
+}
+
+fn config_id(plugin: &str, detector: &str) -> String {
+    format!("{EXTERNAL_PREFIX}{plugin}:{detector}")
+}
+
+impl PluginRunDetection {
+    fn pin(&self, plugin: &str, d: &Detector) -> Option<ProgramPin> {
+        let cap = Capability::Process(d.command.trim().to_owned());
+        self.pins.read().get(&(plugin.to_owned(), cap.to_string())).cloned()
+    }
+}
+
+impl ExternalDetection for PluginRunDetection {
+    fn detect(&self, root: &Path) -> Vec<RunConfig> {
+        let items = self.store.items.read().clone();
+        items
+            .into_iter()
+            .filter(|(_, plugin, d)| self.pin(plugin, d).is_some() && d.files.iter().any(|f| root.join(f).exists()))
+            .map(|(_, plugin, d)| RunConfig {
+                id: config_id(&plugin, &d.id),
+                name: d.name.clone(),
+                kind: "plugin".into(),
+                command: d.command.trim().to_owned(),
+                args: d.args.clone(),
+                cwd: None,
+                env: Default::default(),
+                detected: true,
+                is_test: d.test,
+                debug_adapter: None,
+                allow_parallel: false,
+                extras: Default::default(),
+            })
+            .collect()
+    }
+
+    fn launch(&self, config: &RunConfig) -> Result<PathBuf, String> {
+        let items = self.store.items.read();
+        let (plugin, d) = items
+            .iter()
+            .find(|(_, plugin, d)| config_id(plugin, &d.id) == config.id)
+            .map(|(_, p, d)| (p.clone(), d.clone()))
+            .ok_or_else(|| "the plugin that detected this configuration is no longer enabled".to_owned())?;
+        drop(items);
+        let pin = self.pin(&plugin, &d).ok_or_else(|| {
+            format!("allow process:{} for plugin {plugin} in Settings › Plugins to run this configuration", d.command)
+        })?;
+        pin.verify().map(Path::to_path_buf)
+    }
+}

crates/ide-host/src/plugins/theme.rs

@@ -1,9 +1,21 @@
-//! Theme contributions: design-token overrides applied as CSS variables on `:root`.
-//! Theme and editor-scheme files are JSON that may contain `//` and `/* */` comments.
+//! The `themes` extension point: design-token overrides applied as CSS
+//! variables on `:root`. Theme and editor-scheme files are JSON that may
+//! contain `//` and `/* */` comments.
+//!
+//! ```toml
+//! [[contributes.themes]]
+//! path = "themes/harbor-night.json"
+//! editor-scheme = "themes/harbor-night.scheme.json"   # optional
+//! ```
 
+use ide_extension::{ExtensionPoint, Package, Placement, Prepared, UiContribution, UiStore, decode};
 use serde::{Deserialize, Serialize};
 use specta::Type;
 use std::collections::BTreeMap;
+use std::path::PathBuf;
+use std::sync::Arc;
+
+pub const POINT_ID: &str = "themes";
 
 const MAX_TOKENS: usize = 512;
 const MAX_VALUE_LEN: usize = 256;
@@ -48,7 +60,7 @@ impl ThemeDef {
     }
 
     pub fn validate(&self) -> Result<(), String> {
-        crate::manifest::validate_command_id(&self.id).map_err(|e| e.replace("command id", "theme id"))?;
+        ide_extension::validate_item_id(&self.id, "theme id")?;
         if self.name.trim().is_empty() {
             return Err("theme name must not be empty".into());
         }
@@ -71,6 +83,55 @@ impl ThemeDef {
     }
 }
 
+pub struct ThemesPoint {
+    store: Arc<UiStore>,
+}
+
+impl ThemesPoint {
+    pub fn new(store: Arc<UiStore>) -> Self {
+        Self { store }
+    }
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "kebab-case", deny_unknown_fields)]
+struct Decl {
+    path: PathBuf,
+    #[serde(default)]
+    editor_scheme: Option<PathBuf>,
+}
+
+impl ExtensionPoint for ThemesPoint {
+    fn id(&self) -> &'static str {
+        POINT_ID
+    }
+
+    fn placement(&self) -> Placement {
+        Placement::Ui
+    }
+
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+        let decl: Decl = decode(POINT_ID, decl)?;
+        let path = &decl.path;
+        let mut theme = ThemeDef::parse(&pkg.read_text(path)?).map_err(|e| format!("{}: {e}", path.display()))?;
+        let mut files = vec![path.clone()];
+        if let Some(scheme) = &decl.editor_scheme {
+            files.push(scheme.clone());
+            theme.merge_editor_scheme(&pkg.read_text(scheme)?).map_err(|e| format!("{}: {e}", scheme.display()))?;
+        }
+        let item = UiContribution {
+            plugin_id: pkg.id().to_owned(),
+            point: POINT_ID.into(),
+            key: theme.id.clone(),
+            decl: serde_json::to_value(&theme).map_err(|e| e.to_string())?,
+        };
+        let store = self.store.clone();
+        let mut prepared = Prepared::new(theme.name.clone(), move || Ok(store.insert(item))).key(theme.id);
+        prepared.files = files;
+        Ok(prepared)
+    }
+}
+
 /// Blanks out `//` and `/* */` comments outside strings, keeping newlines so
 /// parse errors still point at the right line.
 fn strip_json_comments(src: &str) -> String {

crates/ide-host/src/plugins/types.rs

@@ -0,0 +1,236 @@
+//! UI-facing plugin types and the event stream.
+
+use super::theme::ThemeDef;
+use ide_extension::{CapabilityInfo, ContributionInfo, UiContribution};
+pub use ide_plugin::{ActionPerformed, ActionSource, EventKind, NotificationLevel, StatusItem, WorkbenchEvent};
+use serde::{Deserialize, Serialize};
+use specta::Type;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub enum PluginSource {
+    /// Installed under `<app-data>/plugins/<id>/`.
+    Installed,
+    /// Loaded from `<project>/.openidea/plugins/<dir>/` while that project is open.
+    Dev,
+    /// A development plugin linked from any folder (`openidea-plugin link`).
+    Linked,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub enum PluginStatus {
+    /// Code instantiated and activated.
+    Active,
+    /// Has code that has not been needed yet: contributions are live, no Wasm instance.
+    Inactive,
+    /// No code; contributions only.
+    Static,
+    Disabled,
+    /// Waiting for the user to confirm its permissions (project and new plugins).
+    NeedsConsent,
+    /// Failed to load, or failed repeatedly and was stopped for this session (see `error`).
+    Failed,
+}
+
+impl PluginStatus {
+    /// Contributions are in effect.
+    pub fn is_live(self) -> bool {
+        matches!(self, Self::Active | Self::Inactive | Self::Static)
+    }
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PluginInfo {
+    pub id: String,
+    pub name: String,
+    pub version: String,
+    pub description: String,
+    pub authors: Vec<String>,
+    pub homepage: Option<String>,
+    pub change_notes: Option<String>,
+    pub source: PluginSource,
+    /// Package directory.
+    pub path: ide_core::IpcPath,
+    pub enabled: bool,
+    pub status: PluginStatus,
+    pub error: Option<String>,
+    pub has_code: bool,
+    /// Declared capabilities with risk and grant state.
+    pub capabilities: Vec<CapabilityInfo>,
+    /// What it contributes while live (point + label).
+    pub contributions: Vec<ContributionInfo>,
+    /// `activation` events of the manifest.
+    pub activation: Vec<String>,
+    /// Non-fatal problems (unsupported contribution points).
+    pub warnings: Vec<String>,
+    /// Statistics of this session.
+    pub stats: PluginStats,
+    /// The marketplace publisher whose signature the package carries (none: unsigned or untrusted).
+    pub publisher: Option<String>,
+    /// The version an update replaced, to roll back to.
+    pub previous_version: Option<String>,
+}
+
+#[derive(Clone, Copy, Debug, Default, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PluginStats {
+    pub activations: u32,
+    /// Last activation (instantiate + `activate`), ms.
+    pub activation_ms: f64,
+    pub calls: u32,
+    pub errors: u32,
+    /// Slowest call, ms.
+    pub max_call_ms: f64,
+    /// 95th percentile of the recent calls, ms.
+    pub p95_call_ms: f64,
+    /// Edit-path calls whose result came too late and was dropped.
+    pub slow_calls: u32,
+    /// Traps (panics, budgets, permission violations); each drops the instance.
+    pub crashes: u32,
+    /// Instances reclaimed after being idle.
+    pub reclaims: u32,
+}
+
+/// Number of declarations of one extension point.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ContributionCount {
+    pub point: String,
+    pub count: u32,
+}
+
+/// A plugin package available for installation from a local catalog
+/// directory (the samples shipped with the IDE). Not installed by listing it.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct CatalogPlugin {
+    pub id: String,
+    pub name: String,
+    pub version: String,
+    pub description: String,
+    pub authors: Vec<String>,
+    pub homepage: Option<String>,
+    pub change_notes: Option<String>,
+    /// Package directory; install with `install_from_dir(path)`.
+    pub path: ide_core::IpcPath,
+    pub has_code: bool,
+    pub capabilities: Vec<CapabilityInfo>,
+    pub contributions: Vec<ContributionCount>,
+    /// Why the package cannot be installed as is (e.g. its WASM is not built).
+    pub problem: Option<String>,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ActiveTheme {
+    pub plugin_id: String,
+    pub theme: ThemeDef,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PluginsSnapshot {
+    pub plugins: Vec<PluginInfo>,
+    pub active_theme: Option<ActiveTheme>,
+    /// UI contributions of live plugins, projected by the client.
+    pub ui: Vec<UiContribution>,
+}
+
+/// Backend → UI notifications (Tauri event `ide://plugin`).
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(tag = "type", rename_all = "camelCase")]
+pub enum PluginEvent {
+    /// Plugins, their status or their contributions changed: re-fetch `plugin_list`.
+    CommandsChanged,
+    #[serde(rename_all = "camelCase")]
+    Notification { plugin_id: String, level: NotificationLevel, title: String, body: String },
+    /// A plugin's status bar item was set (`item`) or removed.
+    #[serde(rename_all = "camelCase")]
+    StatusItemChanged { plugin_id: String, id: String, item: Option<StatusItem> },
+    /// A plugin began a task: show it with the background tasks.
+    #[serde(rename_all = "camelCase")]
+    TaskStarted { plugin_id: String, task_id: String, title: String, cancellable: bool },
+    #[serde(rename_all = "camelCase")]
+    TaskProgress { plugin_id: String, task_id: String, done: u32, total: Option<u32>, message: Option<String> },
+    #[serde(rename_all = "camelCase")]
+    TaskEnded { plugin_id: String, task_id: String },
+    /// The kinds of workbench events plugins want changed: re-fetch
+    /// `plugin_event_kinds` (the UI reports only those).
+    SubscriptionsChanged,
+    #[serde(rename_all = "camelCase")]
+    ThemeChanged { theme: Option<ActiveTheme> },
+    /// A plugin needs capabilities the user has not granted yet (first use
+    /// after migrating from 0.1): show its consent dialog.
+    #[serde(rename_all = "camelCase")]
+    ConsentRequested { plugin_id: String, capabilities: Vec<CapabilityInfo> },
+    /// A view (or the custom editors) of a plugin must be rendered again.
+    #[serde(rename_all = "camelCase")]
+    ViewChanged { plugin_id: String, view: String },
+    /// For the script of a view's `html` body.
+    #[serde(rename_all = "camelCase")]
+    ViewMessage { plugin_id: String, view: String, message: String },
+    /// Open a terminal running `program` (already approved and verified).
+    #[serde(rename_all = "camelCase")]
+    OpenTerminal {
+        plugin_id: String,
+        title: String,
+        program: ide_core::IpcPath,
+        args: Vec<String>,
+        cwd: ide_core::IpcPath,
+    },
+    /// Plugin languages, or the servers they may start, changed: re-fetch
+    /// `languages` (the host re-detects open documents: [`crate::Host::plugin_languages_changed`]).
+    LanguagesChanged,
+}
+
+/// Delivers events to the UI. `client` is the window that invoked the plugin
+/// (`None` = broadcast, e.g. during activation).
+pub trait PluginEventSink: Send + Sync {
+    fn emit(&self, client: Option<&str>, event: PluginEvent);
+}
+
+impl<F: Fn(Option<&str>, PluginEvent) + Send + Sync> PluginEventSink for F {
+    fn emit(&self, client: Option<&str>, event: PluginEvent) {
+        self(client, event)
+    }
+}
+
+/// The focused editor when a plugin command is invoked.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PluginEditor {
+    pub path: String,
+    pub language: String,
+    pub selections: Vec<ide_core::Range>,
+}
+
+impl PluginEditor {
+    pub fn context(self) -> ide_plugin::EditorContext {
+        ide_plugin::EditorContext { path: self.path.into(), language: self.language, selections: self.selections }
+    }
+}
+
+/// A plugin's status bar item.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PluginStatusItem {
+    pub plugin_id: String,
+    pub id: String,
+    pub item: StatusItem,
+}
+
+/// A gutter marker from a plugin's `line-markers` provider.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct LineMarkerInfo {
+    pub plugin_id: String,
+    /// 0-based.
+    pub line: u32,
+    /// `navigate` (default), `implemented`, `implementing`, `run`.
+    pub icon: Option<String>,
+    pub tooltip: String,
+    /// Opened on click.
+    pub target: Option<ide_core::Location>,
+}

crates/ide-host/src/plugins/ui_points.rs

@@ -0,0 +1,544 @@
+//! Declarative UI contributions: menus, key
+//! bindings, status bar items and settings (L0, shown before any code runs),
+//! and the views and custom editors whose content plugin code renders (L2).
+//! Everything is validated here; the client only projects the JSON.
+//!
+//! ```toml
+//! [[contributes.menus]]
+//! menu = "editor.context"          # projectView.context, editorTab.context, tools
+//! command = "check"
+//! when = "editorLang == java"
+//!
+//! [[contributes.keymaps]]
+//! command = "check"
+//! key = "Ctrl+Alt+C"               # `mac` for a different binding on macOS (`Meta+Alt+C`)
+//!
+//! [[contributes.statusBar]]
+//! id = "branch"
+//! text = "…"                       # code replaces it with `set-status-item("branch", …)`
+//! command = "show"
+//!
+//! [contributes.settings]
+//! schema = "settings.schema.json"  # {"properties": {"key": {"type": "boolean", "default": true, …}}}
+//!
+//! [[contributes.views]]
+//! id = "jobs"
+//! title = "Jobs"
+//! icon = "server"
+//! location = "right"               # left, right, bottom
+//!
+//! [[contributes.customEditors]]
+//! id = "table"
+//! title = "Table"
+//! patterns = ["*.csv", "*.tsv"]
+//! priority = "default"             # or "option": only through Open With
+//! layout = "tab"                   # or "split" / "preview": beside the text editor
+//! web = "web/index.html"           # a web page from the package instead of rendered content
+//!
+//! [[contributes.fileIcons]]
+//! id = "drawing"
+//! patterns = ["*.excalidraw"]
+//! icon = "icons/drawing.svg"
+//! iconDark = "icons/drawing_dark.svg"
+//!
+//! [[contributes.fileTemplates]]
+//! id = "drawing"
+//! name = "Excalidraw Drawing"
+//! extension = "excalidraw"
+//! path = "templates/drawing.excalidraw"
+//! ```
+
+use ide_extension::{Package, UiDecl, decode, validate_item_id, validate_when};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use std::collections::BTreeSet;
+use std::path::PathBuf;
+
+pub const MENUS: &str = "menus";
+pub const KEYMAPS: &str = "keymaps";
+pub const STATUS_BAR: &str = "statusBar";
+pub const SETTINGS: &str = "settings";
+pub const VIEWS: &str = "views";
+pub const CUSTOM_EDITORS: &str = "customEditors";
+pub const FILE_ICONS: &str = "fileIcons";
+pub const FILE_TEMPLATES: &str = "fileTemplates";
+
+const MENU_IDS: [&str; 4] = ["editor.context", "projectView.context", "editorTab.context", "tools"];
+const MAX_TITLE: usize = 256;
+const MAX_SETTINGS: usize = 200;
+const MAX_PATTERNS: usize = 16;
+
+/// Command ids the package declares.
+fn commands(pkg: &Package) -> BTreeSet<String> {
+    pkg.manifest
+        .declarations(super::COMMANDS)
+        .iter()
+        .filter_map(|d| d.get("id").and_then(|v| v.as_str()).map(str::to_owned))
+        .collect()
+}
+
+fn declared_command(pkg: &Package, point: &str, command: &str) -> Result<(), String> {
+    if commands(pkg).contains(command) {
+        Ok(())
+    } else {
+        Err(format!("contributes.{point}: command {command:?} is not declared under [[contributes.commands]]"))
+    }
+}
+
+fn title(point: &str, t: &str) -> Result<(), String> {
+    if t.trim().is_empty() || t.len() > MAX_TITLE {
+        return Err(format!("contributes.{point}: titles are 1–{MAX_TITLE} bytes"));
+    }
+    Ok(())
+}
+
+fn json<T: Serialize>(v: &T) -> Result<Value, String> {
+    serde_json::to_value(v).map_err(|e| e.to_string())
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct MenuDecl {
+    menu: String,
+    command: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    when: Option<String>,
+}
+
+pub(super) fn menu(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: MenuDecl = decode(MENUS, decl)?;
+    if !MENU_IDS.contains(&d.menu.as_str()) {
+        return Err(format!("contributes.menus: unknown menu {:?} (one of {})", d.menu, MENU_IDS.join(", ")));
+    }
+    declared_command(pkg, MENUS, &d.command)?;
+    if let Some(w) = &d.when {
+        validate_when(w).map_err(|e| format!("contributes.menus: {e}"))?;
+    }
+    Ok(UiDecl::new(format!("{}/{}", d.menu, d.command), d.command.clone(), json(&d)?))
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct KeymapDecl {
+    command: String,
+    key: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    mac: Option<String>,
+}
+
+const MODIFIERS: [&str; 4] = ["Meta", "Ctrl", "Alt", "Shift"];
+const NAMED_KEYS: [&str; 22] = [
+    "Enter",
+    "Escape",
+    "Tab",
+    "Space",
+    "Backspace",
+    "Delete",
+    "Insert",
+    "Home",
+    "End",
+    "PageUp",
+    "PageDown",
+    "Up",
+    "Down",
+    "Left",
+    "Right",
+    "Minus",
+    "Equal",
+    "Comma",
+    "Period",
+    "Slash",
+    "Semicolon",
+    "Quote",
+];
+
+/// `Ctrl+Alt+C`, `Meta+K Meta+C` (a chord): at least one modifier per
+/// stroke but for function keys, so plugins can't take plain typing.
+pub fn validate_binding(binding: &str) -> Result<(), String> {
+    let strokes: Vec<&str> = binding.split(' ').collect();
+    if strokes.is_empty() || strokes.len() > 2 {
+        return Err(format!("{binding:?}: one stroke, or two for a chord"));
+    }
+    for stroke in strokes {
+        let parts: Vec<&str> = stroke.split('+').collect();
+        let (key, mods) = parts.split_last().ok_or_else(|| format!("{binding:?}: empty stroke"))?;
+        let mut seen = BTreeSet::new();
+        for m in mods {
+            if !MODIFIERS.contains(m) || !seen.insert(*m) {
+                return Err(format!("{binding:?}: unknown or repeated modifier {m:?}"));
+            }
+        }
+        let function = key.strip_prefix('F').and_then(|n| n.parse::<u8>().ok()).is_some_and(|n| (1..=24).contains(&n));
+        let plain = key.len() == 1 && key.chars().all(|c| c.is_ascii_uppercase() || c.is_ascii_digit());
+        if !(function || plain || NAMED_KEYS.contains(key)) {
+            return Err(format!("{binding:?}: unknown key {key:?}"));
+        }
+        if !function && seen.iter().all(|m| *m == "Shift") {
+            return Err(format!("{binding:?}: needs Ctrl, Alt or Meta (plain keys are for typing)"));
+        }
+    }
+    Ok(())
+}
+
+pub(super) fn keymap(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: KeymapDecl = decode(KEYMAPS, decl)?;
+    declared_command(pkg, KEYMAPS, &d.command)?;
+    validate_binding(&d.key).map_err(|e| format!("contributes.keymaps: {e}"))?;
+    if let Some(m) = &d.mac {
+        validate_binding(m).map_err(|e| format!("contributes.keymaps: {e}"))?;
+    }
+    Ok(UiDecl::new(d.command.clone(), d.key.clone(), json(&d)?))
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct StatusDecl {
+    id: String,
+    text: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    tooltip: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    command: Option<String>,
+    #[serde(default = "right")]
+    align: String,
+    #[serde(default)]
+    priority: u32,
+}
+
+fn right() -> String {
+    "right".into()
+}
+
+pub(super) fn status_item(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: StatusDecl = decode(STATUS_BAR, decl)?;
+    validate_item_id(&d.id, "status bar item id")?;
+    if d.text.is_empty() || d.text.len() > 128 || d.tooltip.as_ref().is_some_and(|t| t.len() > 1024) {
+        return Err(format!("status bar item {:?}: `text` 1–128 bytes, `tooltip` up to 1 KiB", d.id));
+    }
+    if d.align != "left" && d.align != "right" {
+        return Err(format!("status bar item {:?}: `align` is left or right", d.id));
+    }
+    if d.priority > 1000 {
+        return Err(format!("status bar item {:?}: `priority` is 0–1000", d.id));
+    }
+    if let Some(c) = &d.command {
+        declared_command(pkg, STATUS_BAR, c)?;
+    }
+    Ok(UiDecl::new(d.id.clone(), d.text.clone(), json(&d)?))
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
+struct SettingsDecl {
+    #[serde(default)]
+    title: Option<String>,
+    schema: PathBuf,
+}
+
+#[derive(Debug, Deserialize)]
+struct SchemaFile {
+    properties: serde_json::Map<String, Value>,
+}
+
+/// One setting of a plugin.
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct SettingSchema {
+    pub key: String,
+    /// `boolean`, `string`, `number` or `integer`.
+    #[serde(rename = "type")]
+    pub kind: String,
+    pub title: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    pub default: Value,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub options: Option<Vec<String>>,
+    #[serde(default)]
+    pub multiline: bool,
+}
+
+impl SettingSchema {
+    /// Whether `v` is a valid value of this setting.
+    pub fn accepts(&self, v: &Value) -> bool {
+        match self.kind.as_str() {
+            "boolean" => v.is_boolean(),
+            "integer" => v.is_i64() || v.is_u64(),
+            "number" => v.is_number(),
+            _ => v
+                .as_str()
+                .is_some_and(|s| s.len() <= 64 << 10 && self.options.as_ref().is_none_or(|o| o.iter().any(|x| x == s))),
+        }
+    }
+}
+
+fn setting(key: &str, raw: &Value) -> Result<SettingSchema, String> {
+    if key.is_empty() || key.len() > 64 || !key.chars().all(|c| c.is_ascii_alphanumeric() || "-_.".contains(c)) {
+        return Err(format!("setting {key:?}: keys are 1–64 of [A-Za-z0-9._-]"));
+    }
+    let o = raw.as_object().ok_or_else(|| format!("setting {key:?}: expected an object"))?;
+    let kind = o.get("type").and_then(Value::as_str).unwrap_or("");
+    let default = match kind {
+        "boolean" => o.get("default").cloned().unwrap_or(Value::Bool(false)),
+        "string" => o.get("default").cloned().unwrap_or(Value::String(String::new())),
+        "number" | "integer" => o.get("default").cloned().unwrap_or(Value::from(0)),
+        _ => return Err(format!("setting {key:?}: `type` is boolean, string, number or integer")),
+    };
+    let options = match o.get("enum") {
+        None => None,
+        Some(Value::Array(a)) if kind == "string" && !a.is_empty() && a.len() <= 100 => Some(
+            a.iter()
+                .map(|v| v.as_str().map(str::to_owned).ok_or_else(|| format!("setting {key:?}: `enum` lists strings")))
+                .collect::<Result<Vec<_>, _>>()?,
+        ),
+        Some(_) => return Err(format!("setting {key:?}: `enum` is 1–100 strings of a string setting")),
+    };
+    let text = |name: &str, max: usize| -> Result<Option<String>, String> {
+        match o.get(name) {
+            None => Ok(None),
+            Some(Value::String(s)) if s.len() <= max => Ok(Some(s.clone())),
+            Some(_) => Err(format!("setting {key:?}: `{name}` is a string up to {max} bytes")),
+        }
+    };
+    let s = SettingSchema {
+        key: key.to_owned(),
+        kind: kind.to_owned(),
+        title: text("title", MAX_TITLE)?.unwrap_or_else(|| key.to_owned()),
+        description: text("description", 4096)?,
+        default,
+        options,
+        multiline: o.get("multiline").and_then(Value::as_bool).unwrap_or(false),
+    };
+    if !s.accepts(&s.default) {
+        return Err(format!("setting {key:?}: the default does not match its type"));
+    }
+    Ok(s)
+}
+
+/// The validated settings of a `[contributes.settings]` schema file.
+pub fn parse_settings_schema(text: &str) -> Result<Vec<SettingSchema>, String> {
+    let file: SchemaFile = serde_json::from_str(text).map_err(|e| e.to_string())?;
+    if file.properties.len() > MAX_SETTINGS {
+        return Err(format!("more than {MAX_SETTINGS} settings"));
+    }
+    file.properties.iter().map(|(k, v)| setting(k, v)).collect()
+}
+
+pub(super) fn settings(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: SettingsDecl = decode(SETTINGS, decl)?;
+    let text = pkg.read_text(&d.schema)?;
+    let properties = parse_settings_schema(&text).map_err(|e| format!("{}: {e}", d.schema.display()))?;
+    let title = d.title.unwrap_or_else(|| pkg.manifest.name.clone());
+    title_ok(&title)?;
+    let mut decl =
+        UiDecl::new("settings", title.clone(), serde_json::json!({ "title": title, "properties": properties }));
+    decl.files.push(d.schema);
+    Ok(decl)
+}
+
+fn title_ok(t: &str) -> Result<(), String> {
+    title(SETTINGS, t)
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct ViewDecl {
+    id: String,
+    title: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    icon: Option<String>,
+    #[serde(default = "right")]
+    location: String,
+    /// A web page of the package (`web/index.html`) instead of content the code renders.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    web: Option<String>,
+}
+
+/// The files of a `web` entry, or a check that the code renders the view.
+fn web_or_code(pkg: &Package, web: Option<&str>, what: &str) -> Result<Vec<PathBuf>, String> {
+    match web {
+        Some(entry) => super::web::web_files(pkg, entry, what),
+        None if pkg.manifest.wasm.is_none() => {
+            Err(format!("{what}: give a web page (`web`) or the code that renders it (`wasm`)"))
+        }
+        None => Ok(Vec::new()),
+    }
+}
+
+pub(super) fn view(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: ViewDecl = decode(VIEWS, decl)?;
+    validate_item_id(&d.id, "view id")?;
+    title(VIEWS, &d.title)?;
+    let files = web_or_code(pkg, d.web.as_deref(), &format!("view {:?}", d.id))?;
+    if !["left", "right", "bottom"].contains(&d.location.as_str()) {
+        return Err(format!("view {:?}: `location` is left, right or bottom", d.id));
+    }
+    if d.icon.as_ref().is_some_and(|i| i.len() > 64) {
+        return Err(format!("view {:?}: icon names are up to 64 bytes", d.id));
+    }
+    let mut out = UiDecl::new(d.id.clone(), d.title.clone(), json(&d)?);
+    out.files = files;
+    Ok(out)
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+struct CustomEditorDecl {
+    id: String,
+    title: String,
+    patterns: Vec<String>,
+    #[serde(default = "default_priority")]
+    priority: String,
+    /// `tab`: the file opens in this editor's own tab. `split` / `preview`:
+    /// the file opens in the text editor with this editor beside it (Editor /
+    /// Editor and Preview / Preview); the value is the layout files start in.
+    #[serde(default = "default_layout")]
+    layout: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    web: Option<String>,
+}
+
+fn default_priority() -> String {
+    "default".into()
+}
+
+fn default_layout() -> String {
+    "tab".into()
+}
+
+/// File name globs (`*.csv`, `{a,b}.json`): no directories.
+fn file_patterns(patterns: &[String], what: &str) -> Result<(), String> {
+    if patterns.is_empty() || patterns.len() > MAX_PATTERNS {
+        return Err(format!("{what}: 1–{MAX_PATTERNS} file name `patterns`"));
+    }
+    for p in patterns {
+        if p.is_empty() || p.len() > 128 || p.contains(['/', '\\']) || globset::Glob::new(p).is_err() {
+            return Err(format!("{what}: invalid file name pattern {p:?}"));
+        }
+    }
+    Ok(())
+}
+
+pub(super) fn custom_editor(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: CustomEditorDecl = decode(CUSTOM_EDITORS, decl)?;
+    validate_item_id(&d.id, "custom editor id")?;
+    title(CUSTOM_EDITORS, &d.title)?;
+    let what = format!("custom editor {:?}", d.id);
+    let files = web_or_code(pkg, d.web.as_deref(), &what)?;
+    file_patterns(&d.patterns, &what)?;
+    if d.priority != "default" && d.priority != "option" {
+        return Err(format!("{what}: `priority` is default or option"));
+    }
+    if !["tab", "split", "preview"].contains(&d.layout.as_str()) {
+        return Err(format!("{what}: `layout` is tab, split or preview"));
+    }
+    let mut out = UiDecl::new(d.id.clone(), d.title.clone(), json(&d)?);
+    out.files = files;
+    Ok(out)
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+struct FileIconDecl {
+    id: String,
+    patterns: Vec<String>,
+    icon: PathBuf,
+    #[serde(default)]
+    icon_dark: Option<PathBuf>,
+}
+
+/// Asset id of a file icon's SVG (`dark`: its dark-theme variant).
+pub fn file_icon_asset(id: &str, dark: bool) -> String {
+    format!("fileIcon/{id}/{}", if dark { "dark" } else { "light" })
+}
+
+/// `[[contributes.fileIcons]]`: an icon for the files matching `patterns`,
+/// whatever icon theme is in use (the user's own file type icons still win).
+pub(super) fn file_icon(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: FileIconDecl = decode(FILE_ICONS, decl)?;
+    validate_item_id(&d.id, "file icon id")?;
+    let what = format!("file icon {:?}", d.id);
+    file_patterns(&d.patterns, &what)?;
+    let mut files = Vec::new();
+    let mut assets = Vec::new();
+    for (path, dark) in [(Some(&d.icon), false), (d.icon_dark.as_ref(), true)] {
+        let Some(path) = path else { continue };
+        let svg = super::icons::read_icon(pkg, path)?;
+        assets.push((file_icon_asset(&d.id, dark), svg));
+        files.push(path.clone());
+    }
+    let json = serde_json::json!({ "id": d.id, "patterns": d.patterns, "dark": d.icon_dark.is_some() });
+    let mut out = UiDecl::new(d.id.clone(), d.patterns.join(", "), json);
+    out.files = files;
+    out.assets = assets;
+    Ok(out)
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+struct FileTemplateDecl {
+    id: String,
+    name: String,
+    /// Without the dot.
+    extension: String,
+    /// The new file's content (`$NAME$`, `$END$` and the other template variables work).
+    path: PathBuf,
+}
+
+const MAX_TEMPLATE: usize = 256 << 10;
+
+/// `[[contributes.fileTemplates]]`: an entry of the New menu.
+pub(super) fn file_template(pkg: &Package, decl: toml::Value) -> Result<UiDecl, String> {
+    let d: FileTemplateDecl = decode(FILE_TEMPLATES, decl)?;
+    validate_item_id(&d.id, "file template id")?;
+    title(FILE_TEMPLATES, &d.name)?;
+    let what = format!("file template {:?}", d.id);
+    let ext = d.extension.trim_start_matches('.');
+    if ext.is_empty()
+        || ext.len() > 32
+        || !ext.chars().all(|c| c.is_ascii_alphanumeric() || matches!(c, '.' | '-' | '_'))
+    {
+        return Err(format!("{what}: `extension` is a file extension like \"md\" ({:?})", d.extension));
+    }
+    let body = pkg.read_text(&d.path)?;
+    if body.len() > MAX_TEMPLATE {
+        return Err(format!("{what}: {} is larger than {} KiB", d.path.display(), MAX_TEMPLATE >> 10));
+    }
+    let json = serde_json::json!({ "id": d.id, "name": d.name, "extension": ext, "body": body });
+    let mut out = UiDecl::new(d.id.clone(), d.name.clone(), json);
+    out.files = vec![d.path.clone()];
+    Ok(out)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn bindings_need_a_modifier() {
+        for ok in ["Ctrl+Alt+C", "Meta+Shift+K", "F5", "Shift+F6", "Meta+K Meta+C", "Alt+Enter"] {
+            assert!(validate_binding(ok).is_ok(), "{ok}");
+        }
+        for bad in ["C", "Shift+C", "Hyper+C", "Ctrl+Ctrl+C", "Ctrl+é", "Ctrl+A B C", ""] {
+            assert!(validate_binding(bad).is_err(), "{bad}");
+        }
+    }
+
+    #[test]
+    fn settings_schemas_are_typed() {
+        let s = parse_settings_schema(
+            r#"{"properties": {
+                "context": {"type": "string", "title": "Context", "default": ""},
+                "watch": {"type": "boolean", "default": true},
+                "mode": {"type": "string", "enum": ["a", "b"], "default": "b"},
+                "limit": {"type": "integer", "default": 100}
+            }}"#,
+        )
+        .unwrap();
+        assert_eq!(s.len(), 4);
+        assert!(s.iter().find(|x| x.key == "mode").unwrap().accepts(&Value::from("a")));
+        assert!(!s.iter().find(|x| x.key == "mode").unwrap().accepts(&Value::from("c")));
+        assert!(parse_settings_schema(r#"{"properties": {"x": {"type": "string", "default": 3}}}"#).is_err());
+        assert!(parse_settings_schema(r#"{"properties": {"x": {"type": "object"}}}"#).is_err());
+    }
+}

crates/ide-host/src/plugins/views.rs

@@ -0,0 +1,92 @@
+//! Declarative views and custom editors as the
+//! window commands `plugin_view_render` / `plugin_view_event` serve them —
+//! the desktop for local projects, `openidea-server` for remote ones.
+
+use super::{PluginEditor, PluginHost};
+use ide_core::{DocId, IdeError, IdeResult};
+use ide_plugin::{EditorContext, Invocation, View, ViewEvent, Viewport};
+use std::sync::Arc;
+
+/// The window's project, plus the editor the call is about: the document a
+/// custom editor shows, else (a tool window) the window's active editor, as
+/// a command gets it, so a view's buttons can act on what the user is editing.
+pub fn view_invocation(
+    host: &crate::Host,
+    window: &str,
+    doc: Option<DocId>,
+    editor: Option<PluginEditor>,
+) -> IdeResult<Invocation> {
+    let project = host.project(window).ok();
+    let editor = match doc {
+        None => editor.map(PluginEditor::context),
+        Some(doc) => {
+            let project = project.as_ref().ok_or_else(|| IdeError::not_found("no project is open in this window"))?;
+            let info = project.documents.snapshot(doc)?;
+            Some(EditorContext { path: info.path.0, language: info.language.0, selections: Vec::new() })
+        }
+    };
+    Ok(Invocation { client: Some(window.to_owned()), workspace_root: project.as_ref().map(|p| p.root.clone()), editor })
+}
+
+async fn blocking<T: Send + 'static>(f: impl FnOnce() -> IdeResult<T> + Send + 'static) -> IdeResult<T> {
+    tokio::task::spawn_blocking(f).await.map_err(|e| IdeError::internal(e.to_string()))?
+}
+
+#[allow(clippy::too_many_arguments)]
+pub async fn render(
+    host: &crate::Host,
+    plugins: Arc<PluginHost>,
+    window: &str,
+    plugin_id: String,
+    view: String,
+    viewport: Option<Viewport>,
+    doc: Option<DocId>,
+    editor: Option<PluginEditor>,
+) -> IdeResult<View> {
+    let invocation = view_invocation(host, window, doc, editor)?;
+    blocking(move || plugins.render_view(&plugin_id, &view, viewport, invocation)).await
+}
+
+#[allow(clippy::too_many_arguments)]
+pub async fn event(
+    host: &crate::Host,
+    plugins: Arc<PluginHost>,
+    window: &str,
+    plugin_id: String,
+    view: String,
+    event: ViewEvent,
+    doc: Option<DocId>,
+    editor: Option<PluginEditor>,
+) -> IdeResult<()> {
+    let invocation = view_invocation(host, window, doc, editor)?;
+    blocking(move || plugins.view_event(&plugin_id, &view, event, invocation)).await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{Host, HostConfig};
+
+    #[tokio::test]
+    async fn a_tool_window_call_carries_the_active_editor() {
+        let tmp = tempfile::tempdir().unwrap();
+        let host = Host::new(HostConfig {
+            config_dir: tmp.path().join("config"),
+            data_dir: tmp.path().join("data"),
+            local_data_dir: tmp.path().join("data"),
+            languages: Arc::new(ide_language::LanguageRegistry::load(None).unwrap()),
+            syntax: Arc::default(),
+            sink_for: Box::new(|_| Arc::new(ide_core::NullSink)),
+            owner: |w| w,
+            runtime: tokio::runtime::Handle::current(),
+            project_environment: false,
+        });
+        let range = ide_core::Range::new(ide_core::Pos::new(1, 0), ide_core::Pos::new(1, 4));
+        let active = PluginEditor { path: "/p/a.rs".into(), language: "rust".into(), selections: vec![range] };
+        let inv = view_invocation(&host, "main", None, Some(active)).unwrap();
+        let editor = inv.editor.expect("the active editor");
+        assert_eq!((editor.path.to_string_lossy().as_ref(), editor.selections.as_slice()), ("/p/a.rs", &[range][..]));
+        assert_eq!(inv.client.as_deref(), Some("main"));
+        assert!(view_invocation(&host, "main", None, None).unwrap().editor.is_none());
+    }
+}

crates/ide-host/src/plugins/web.rs

@@ -0,0 +1,245 @@
+//! Web views: a view or custom editor whose UI is a web page shipped in the
+//! package (`web = "web/index.html"`) instead of content the plugin's code
+//! renders.
+//!
+//! The entry's directory is the page's root. Every file under it is part of
+//! the declaration: it is checked when the package is prepared (count, size,
+//! no links leaving the package), copied on install and covered by the
+//! package digest and signature. The client loads the page in a sandboxed
+//! frame (an opaque origin with no network and no IDE API) and fetches its
+//! files through [`PluginHost::web_file`] (the desktop's `openidea-plugin`
+//! URL scheme); the page talks to the IDE only through the frame bridge.
+
+use super::PluginHost;
+use ide_core::{IdeError, IdeResult};
+use ide_extension::{Package, check_relative};
+use serde::{Deserialize, Serialize};
+use specta::Type;
+use std::path::{Component, Path, PathBuf};
+
+/// Most files under one web root.
+const MAX_FILES: usize = 4096;
+/// Most bytes under one web root.
+const MAX_BYTES: u64 = 256 << 20;
+/// Deepest directory nesting under a web root.
+const MAX_DEPTH: usize = 16;
+
+/// Checks a declaration's `web` entry: an `.html` file inside a directory of
+/// the package (the directory is what the page can load, so it can't be the
+/// package root), and everything under that directory. Returns those files,
+/// package-relative.
+pub(super) fn web_files(pkg: &Package, entry: &str, what: &str) -> Result<Vec<PathBuf>, String> {
+    let path = Path::new(entry);
+    check_relative(path, "web")?;
+    if entry.contains('\\') || !entry.to_ascii_lowercase().ends_with(".html") {
+        return Err(format!("{what}: `web` names an .html file, `/`-separated ({entry:?})"));
+    }
+    let dir = path.parent().filter(|d| !d.as_os_str().is_empty()).ok_or_else(|| {
+        format!("{what}: put the page in a directory of its own (`web/index.html`): the directory is what it can load")
+    })?;
+    let real_entry = pkg.resolve(path)?;
+    if !real_entry.is_file() {
+        return Err(format!("{what}: {entry} is not a file"));
+    }
+    let root = pkg.resolve(dir)?;
+    let mut files = Vec::new();
+    let mut total = 0u64;
+    let mut stack = vec![(root.clone(), dir.to_path_buf(), 0usize)];
+    while let Some((real, rel, depth)) = stack.pop() {
+        let mut entries: Vec<_> =
+            std::fs::read_dir(&real).map_err(|e| format!("{}: {e}", rel.display()))?.filter_map(Result::ok).collect();
+        entries.sort_by_key(|e| e.file_name());
+        for e in entries {
+            let name = e.file_name();
+            let rel = rel.join(&name);
+            // Links could point anywhere: only what is really in the package counts.
+            let ty = e.file_type().map_err(|err| format!("{}: {err}", rel.display()))?;
+            if ty.is_symlink() {
+                return Err(format!("{what}: {} is a link; web files must be real files", rel.display()));
+            }
+            if ty.is_dir() {
+                if depth + 1 > MAX_DEPTH {
+                    return Err(format!("{what}: {} is nested deeper than {MAX_DEPTH} directories", rel.display()));
+                }
+                stack.push((e.path(), rel, depth + 1));
+                continue;
+            }
+            if name.to_string_lossy() == ".DS_Store" {
+                continue;
+            }
+            let len = e.metadata().map_err(|err| format!("{}: {err}", rel.display()))?.len();
+            if len > ide_extension::MAX_PACKAGE_FILE {
+                return Err(format!(
+                    "{what}: {} is larger than {} MiB",
+                    rel.display(),
+                    ide_extension::MAX_PACKAGE_FILE >> 20
+                ));
+            }
+            total += len;
+            files.push(rel);
+            if files.len() > MAX_FILES || total > MAX_BYTES {
+                return Err(format!(
+                    "{what}: {} holds more than {MAX_FILES} files or {} MiB",
+                    dir.display(),
+                    MAX_BYTES >> 20
+                ));
+            }
+        }
+    }
+    files.sort();
+    Ok(files)
+}
+
+/// The page of a web view, for the client to load in its frame.
+#[derive(Clone, Debug, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct WebPage {
+    /// `<plugin id>/<revision>/<entry>` under the `openidea-plugin` scheme. The
+    /// revision changes with the installed package, so a cached file is never
+    /// stale; relative URLs in the page resolve to the package's files.
+    pub path: String,
+}
+
+/// A file of a web view.
+pub struct WebFile {
+    pub bytes: Vec<u8>,
+    pub mime: &'static str,
+}
+
+impl PluginHost {
+    /// The web roots `plugin` declares (entry directories, package-relative, `/`-terminated).
+    fn web_dirs(&self, plugin: &str) -> Vec<String> {
+        [super::ui_points::VIEWS, super::ui_points::CUSTOM_EDITORS]
+            .iter()
+            .flat_map(|point| self.ui.items(point, Some(plugin)))
+            .filter_map(|item| item.decl.get("web").and_then(|w| w.as_str()).map(str::to_owned))
+            .filter_map(|entry| entry.rsplit_once('/').map(|(dir, _)| format!("{dir}/")))
+            .collect()
+    }
+
+    /// Changes whenever the installed package does (cache key of its web files).
+    fn web_revision(&self, plugin: &super::LoadedPlugin) -> String {
+        let digest = plugin.pkg.digest.as_deref().unwrap_or_default();
+        let short: String = digest.chars().filter(char::is_ascii_alphanumeric).take(16).collect();
+        if short.is_empty() { format!("v{}", plugin.pkg.manifest.version) } else { short }
+    }
+
+    /// The page of `plugin`'s view or custom editor `view`.
+    pub fn web_page(&self, plugin_id: &str, view: &str) -> IdeResult<WebPage> {
+        let plugin = self.get(plugin_id)?;
+        if !plugin.status().is_live() {
+            return Err(IdeError::unavailable(format!("plugin {plugin_id:?} is not enabled")));
+        }
+        let entry = [super::ui_points::VIEWS, super::ui_points::CUSTOM_EDITORS]
+            .iter()
+            .flat_map(|point| self.ui.items(point, Some(plugin_id)))
+            .find(|item| item.key == view)
+            .and_then(|item| item.decl.get("web").and_then(|w| w.as_str()).map(str::to_owned))
+            .ok_or_else(|| IdeError::not_found(format!("plugin {plugin_id:?} has no web view {view:?}")))?;
+        Ok(WebPage { path: format!("{plugin_id}/{}/{entry}", self.web_revision(&plugin)) })
+    }
+
+    /// A file of one of `plugin`'s web views: `path` is `<revision>/<package path>`
+    /// as [`WebPage::path`] makes them. Only files under a declared web root
+    /// of a live plugin are served; the revision must be the installed one.
+    pub fn web_file(&self, plugin_id: &str, path: &str) -> IdeResult<WebFile> {
+        let plugin = self.get(plugin_id)?;
+        if !plugin.status().is_live() {
+            return Err(IdeError::unavailable(format!("plugin {plugin_id:?} is not enabled")));
+        }
+        let (revision, rel) = path.split_once('/').ok_or_else(|| IdeError::not_found(path.to_owned()))?;
+        if revision != self.web_revision(&plugin) {
+            return Err(IdeError::not_found(format!("{path}: not the installed version")));
+        }
+        let rel_path = Path::new(rel);
+        if !rel_path.components().all(|c| matches!(c, Component::Normal(_))) {
+            return Err(IdeError::invalid(format!("{rel}: not a plain relative path")));
+        }
+        if !self.web_dirs(plugin_id).iter().any(|dir| rel.starts_with(dir.as_str())) {
+            return Err(IdeError::not_found(format!("{rel}: not part of a web view")));
+        }
+        let bytes = plugin.pkg.read_bytes(rel_path).map_err(IdeError::not_found)?;
+        Ok(WebFile { bytes, mime: mime(rel) })
+    }
+}
+
+/// Content type by extension; unknown files are opaque bytes (never sniffed as script).
+pub fn mime(path: &str) -> &'static str {
+    let ext = path.rsplit_once('.').map(|(_, e)| e.to_ascii_lowercase()).unwrap_or_default();
+    match ext.as_str() {
+        "html" | "htm" => "text/html; charset=utf-8",
+        "js" | "mjs" | "cjs" => "text/javascript; charset=utf-8",
+        "css" => "text/css; charset=utf-8",
+        "json" | "map" => "application/json",
+        "wasm" => "application/wasm",
+        "svg" => "image/svg+xml",
+        "png" => "image/png",
+        "jpg" | "jpeg" => "image/jpeg",
+        "gif" => "image/gif",
+        "webp" => "image/webp",
+        "avif" => "image/avif",
+        "ico" => "image/x-icon",
+        "woff2" => "font/woff2",
+        "woff" => "font/woff",
+        "ttf" => "font/ttf",
+        "otf" => "font/otf",
+        "txt" | "md" => "text/plain; charset=utf-8",
+        "mp3" => "audio/mpeg",
+        "mp4" => "video/mp4",
+        "webm" => "video/webm",
+        _ => "application/octet-stream",
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ide_extension::Manifest;
+
+    fn pkg(dir: &Path) -> Package {
+        let src = "id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n";
+        Package::new(Manifest::parse(src).unwrap(), dir.to_path_buf())
+    }
+
+    #[test]
+    fn a_web_root_is_its_directory_and_nothing_else() {
+        let tmp = tempfile::tempdir().unwrap();
+        let d = tmp.path();
+        std::fs::create_dir_all(d.join("web/assets/fonts")).unwrap();
+        std::fs::write(d.join("web/index.html"), "<p>hi</p>").unwrap();
+        std::fs::write(d.join("web/assets/app.js"), "1").unwrap();
+        std::fs::write(d.join("web/assets/fonts/a.woff2"), "f").unwrap();
+        std::fs::write(d.join("web/.DS_Store"), "x").unwrap();
+        std::fs::write(d.join("secret.txt"), "no").unwrap();
+        let files = web_files(&pkg(d), "web/index.html", "v").unwrap();
+        let files: Vec<String> = files.iter().map(|f| f.to_string_lossy().replace('\\', "/")).collect();
+        assert_eq!(files, ["web/assets/app.js", "web/assets/fonts/a.woff2", "web/index.html"]);
+
+        std::fs::write(d.join("index.html"), "x").unwrap();
+        let err = |entry: &str| web_files(&pkg(d), entry, "v").err().unwrap_or_default();
+        assert!(err("index.html").contains("directory of its own"), "{}", err("index.html"));
+        assert!(err("web/app.js").contains(".html"));
+        assert!(err("../web/index.html").contains("relative"));
+        assert!(err("web/missing.html").contains("no such file"));
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn links_out_of_a_web_root_are_refused() {
+        let tmp = tempfile::tempdir().unwrap();
+        let d = tmp.path();
+        std::fs::create_dir_all(d.join("web")).unwrap();
+        std::fs::write(d.join("web/index.html"), "x").unwrap();
+        std::os::unix::fs::symlink("/etc/hosts", d.join("web/hosts")).unwrap();
+        assert!(web_files(&pkg(d), "web/index.html", "v").unwrap_err().contains("is a link"));
+    }
+
+    #[test]
+    fn content_types_never_make_unknown_files_scripts() {
+        assert_eq!(mime("a/b.JS"), "text/javascript; charset=utf-8");
+        assert_eq!(mime("x.woff2"), "font/woff2");
+        assert_eq!(mime("x.wasm"), "application/wasm");
+        assert_eq!(mime("x.bin"), "application/octet-stream");
+        assert_eq!(mime("noext"), "application/octet-stream");
+    }
+}

crates/ide-host/src/project.rs

@@ -305,6 +305,7 @@ impl Host {
                     index.update(&changed, &batch.removed);
                     kotlin_bridge.files_changed(changed.iter().chain(&batch.removed));
                     lsp.project_files_changed(batch.created.iter().chain(&batch.removed));
+                    lsp.watched_files_changed(&batch.created, &batch.modified, &batch.removed);
                     // Atomic saves by external tools surface as `created`.
                     documents.on_disk_changed(&changed);
                     // A framework's root marker (`angular.json`) created or deleted: its

crates/ide-host/src/rpc.rs

@@ -9,7 +9,10 @@
 //! * server → client notification `event` `{ window, event }` (an `IdeEvent`
 //!   for that window, or every window when `window` is null);
 //! * server → client notification `channel` `{ id, data }`: one value of a
-//!   streaming argument.
+//!   streaming argument;
+//! * server → client notification `plugin` `{ window, event }` and request
+//!   `plugin_secret` `{ plugin, name }` → `string | null`: code plugins of the
+//!   remote project (`plugins::remote_host`).
 
 use crate::Host;
 use crate::ops::{self, Emit};
@@ -254,6 +257,8 @@ impl Dispatcher {
                 &c.arg::<Option<Vec<String>>>("removedDetectedIds")?.unwrap_or_default(),
             )
         })
+        .add("run_without_derived", |c| async move { ops::run::without_derived(&c.host, &c.window, c.arg("configs")?) })
+        .add("run_apply_settings", |c| async move { ops::run::apply_settings(&c.host, &c.window, c.arg("configs")?) })
         .add("run_system_env", |_| async move { Ok(ide_run::system_env()) })
         .add("run_start", |c| async move {
             let on_output = c.channel("onOutput")?;

crates/ide-host/src/trust.rs

@@ -273,6 +273,7 @@ pub fn restricted_command_allowed(cmd: &str) -> bool {
             | "plugin_set_theme"
             | "plugin_set_theme_frame"
             | "plugin_catalog"
+            | "plugin_assets"
             | "notebook_open"
             | "notebook_get"
             | "notebook_edit"

crates/ide-host/tests/distribution.rs

@@ -0,0 +1,262 @@
+//! Versioned installs with automatic rollback, signed packages from
+//! a static marketplace index, and revocation.
+
+use ide_extension::package::{self, Index, IndexEntry, KeyEntry, Publisher, PublisherKey, Revocation};
+use ide_host::plugins::*;
+use ide_plugin::{Invocation, Limits};
+use parking_lot::Mutex;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+type Events = Arc<Mutex<Vec<PluginEvent>>>;
+
+fn repo() -> PathBuf {
+    Path::new(env!("CARGO_MANIFEST_DIR")).join("../..")
+}
+
+fn copy_dir(from: &Path, to: &Path) {
+    std::fs::create_dir_all(to).unwrap();
+    for entry in std::fs::read_dir(from).unwrap().flatten() {
+        let (src, dst) = (entry.path(), to.join(entry.file_name()));
+        if entry.file_name() == "target" {
+            continue;
+        }
+        if src.is_dir() { copy_dir(&src, &dst) } else { std::fs::copy(&src, &dst).map(|_| ()).unwrap() }
+    }
+}
+
+/// A copy of `from` (under `dir/name`) whose manifest is rewritten by `f`.
+fn variant(from: &Path, dir: &Path, name: &str, f: impl Fn(&str) -> String) -> PathBuf {
+    let pkg = dir.join(name);
+    copy_dir(from, &pkg);
+    let manifest = pkg.join("plugin.toml");
+    std::fs::write(&manifest, f(&std::fs::read_to_string(&manifest).unwrap())).unwrap();
+    pkg
+}
+
+struct Fixture {
+    host: PluginHost,
+    plugins_dir: PathBuf,
+    events: Events,
+    _tmp: tempfile::TempDir,
+    work: PathBuf,
+}
+
+fn fixture() -> Fixture {
+    let tmp = tempfile::tempdir().unwrap();
+    let plugins_dir = tmp.path().join("plugins");
+    let events: Events = Arc::default();
+    let sink = {
+        let events = events.clone();
+        move |_: Option<&str>, e: PluginEvent| events.lock().push(e)
+    };
+    let host = PluginHost::new(plugins_dir.clone(), Arc::new(sink), Limits::default()).unwrap();
+    host.load_all();
+    let work = tmp.path().join("work");
+    std::fs::create_dir_all(&work).unwrap();
+    Fixture { host, plugins_dir, events, work, _tmp: tmp }
+}
+
+fn inv() -> Invocation {
+    Invocation { client: Some("main".into()), workspace_root: None, editor: None }
+}
+
+fn misbehave() -> PathBuf {
+    repo().join("crates/ide-plugin/tests/fixtures/misbehave")
+}
+
+/// P8 acceptance: an update that fails to start rolls back to the version it replaced.
+#[test]
+fn a_failing_update_rolls_back_automatically() {
+    let f = fixture();
+    let v1 = variant(&misbehave(), &f.work, "v1", |t| t.replace("version = \"0.0.2\"", "version = \"1.0.0\""));
+    f.host.install_from_dir(&v1, &Consent::all()).unwrap();
+    assert_eq!(f.host.run_command("misbehave", "echo", Some("hi"), inv()).unwrap().as_deref(), Some("hi"));
+
+    let broken =
+        variant(&misbehave(), &f.work, "v2", |t| t.replace("version = \"0.0.2\"", "version = \"2.0.0-broken\""));
+    let info = f.host.install_from_dir(&broken, &Consent::all()).unwrap();
+    assert_eq!((info.version.as_str(), info.previous_version.as_deref()), ("2.0.0-broken", Some("1.0.0")));
+    let root = f.plugins_dir.join("misbehave");
+    assert!(root.join("2.0.0-broken").is_dir() && root.join("1.0.0").is_dir(), "versions side by side");
+
+    // Its first start fails: back to 1.0.0, without the user doing anything.
+    f.events.lock().clear();
+    let err = f.host.run_command("misbehave", "echo", Some("x"), inv()).unwrap_err();
+    assert!(err.message.contains("version 1.0.0 was restored"), "{}", err.message);
+    let info = f.host.info_of("misbehave").unwrap();
+    assert_eq!((info.version.as_str(), info.status), ("1.0.0", PluginStatus::Inactive));
+    assert!(!root.join("2.0.0-broken").exists(), "the failed version is removed");
+    assert!(
+        f.events
+            .lock()
+            .iter()
+            .any(|e| matches!(e, PluginEvent::Notification { title, .. } if title.contains("rolled back")))
+    );
+    assert_eq!(f.host.run_command("misbehave", "echo", Some("ok"), inv()).unwrap().as_deref(), Some("ok"));
+
+    // A working update is confirmed by its first start; the user can still roll it back.
+    let v3 = variant(&misbehave(), &f.work, "v3", |t| t.replace("version = \"0.0.2\"", "version = \"3.0.0\""));
+    f.host.install_from_dir(&v3, &Consent::all()).unwrap();
+    f.host.run_command("misbehave", "echo", None, inv()).unwrap();
+    assert_eq!(f.host.info_of("misbehave").unwrap().version, "3.0.0");
+    let info = f.host.roll_back_update("misbehave").unwrap();
+    assert_eq!((info.version.as_str(), info.previous_version.as_deref()), ("1.0.0", None));
+    assert!(f.host.roll_back_update("misbehave").is_err(), "nothing older to go back to");
+
+    // A restart loads the active version.
+    let again = PluginHost::new(f.plugins_dir.clone(), Arc::new(|_: Option<&str>, _| {}), Limits::default()).unwrap();
+    again.load_all();
+    assert_eq!(again.info_of("misbehave").unwrap().version, "1.0.0");
+    f.host.uninstall("misbehave").unwrap();
+    assert!(!root.exists(), "every version goes");
+}
+
+#[test]
+fn installs_from_before_versioning_keep_working_and_move_on_update() {
+    let f = fixture();
+    // The flat layout of earlier releases.
+    copy_dir(&misbehave(), &f.plugins_dir.join("misbehave"));
+    let again = PluginHost::new(f.plugins_dir.clone(), Arc::new(|_: Option<&str>, _| {}), Limits::default()).unwrap();
+    again.load_all();
+    assert_eq!(again.info_of("misbehave").unwrap().version, "0.0.2");
+    let v1 = variant(&misbehave(), &f.work, "v1", |t| t.replace("version = \"0.0.2\"", "version = \"1.0.0\""));
+    let info = again.install_from_dir(&v1, &Consent::all()).unwrap();
+    assert_eq!((info.version.as_str(), info.previous_version.as_deref()), ("1.0.0", Some("0.0.2")));
+    assert!(f.plugins_dir.join("misbehave/0.0.2/plugin.toml").is_file());
+    assert!(f.plugins_dir.join("misbehave/1.0.0/plugin.toml").is_file());
+}
+
+// ---- marketplace ------------------------------------------------------------------
+
+/// `hello` as `acme.hello` at `version`, packed and signed with `key`.
+fn signed_hello(dir: &Path, version: &str, key: &PublisherKey, host: &PluginHost) -> (PathBuf, IndexEntry) {
+    let src = variant(&repo().join("crates/ide-plugin/tests/fixtures/hello"), dir, &format!("src-{version}"), |t| {
+        t.replace("id = \"hello\"", "id = \"acme.hello\"")
+            .replace("version = \"0.3.0\"", &format!("version = \"{version}\""))
+    });
+    let files = host.package_files_of(&src).unwrap();
+    let digest = package::package_digest(&src, &files).unwrap();
+    let sig = key.sign("acme", "acme.hello", version, &digest);
+    let out = dir.join(format!("acme.hello-{version}.oiplugin"));
+    package::pack(&src, &files, &out, Some(&sig)).unwrap();
+    let entry = IndexEntry {
+        id: "acme.hello".into(),
+        name: "Hello".into(),
+        version: version.into(),
+        description: String::new(),
+        authors: vec![],
+        publisher: "acme".into(),
+        download: out.file_name().unwrap().to_string_lossy().into_owned(),
+        digest,
+        capabilities: vec![],
+    };
+    (out, entry)
+}
+
+fn write_index(
+    dir: &Path,
+    key: &PublisherKey,
+    plugins: Vec<IndexEntry>,
+    revoked: Vec<Revocation>,
+    key_revoked: bool,
+) -> String {
+    let index = Index {
+        format: package::INDEX_FORMAT,
+        publishers: vec![Publisher {
+            id: "acme".into(),
+            name: "ACME".into(),
+            keys: vec![KeyEntry { key: key.public_base64(), revoked: key_revoked }],
+        }],
+        plugins,
+        revoked,
+    };
+    let path = dir.join("index.json");
+    std::fs::write(&path, serde_json::to_string(&index).unwrap()).unwrap();
+    path.to_string_lossy().into_owned()
+}
+
+#[test]
+fn signed_marketplace_plugins_install_and_revocations_disable_them() {
+    let f = fixture();
+    let market = f.work.join("market");
+    std::fs::create_dir_all(&market).unwrap();
+    let key = PublisherKey::from_seed([3; 32]);
+    let (_, entry) = signed_hello(&market, "1.0.0", &key, &f.host);
+    let url = write_index(&market, &key, vec![entry.clone()], vec![], false);
+
+    assert!(f.host.refresh_market().is_err(), "no marketplace configured yet");
+    f.host.set_market_url(Some(url.clone()));
+    let listed = f.host.refresh_market().unwrap();
+    assert_eq!((listed[0].entry.id.as_str(), listed[0].installed.as_deref()), ("acme.hello", None));
+
+    let dir = f.host.download_market_plugin("acme.hello").unwrap();
+    let preview = f.host.preview_install(&dir).unwrap();
+    assert_eq!((preview.unsigned, preview.publisher.as_deref()), (false, Some("acme")));
+    let info = f.host.install_from_dir(&dir, &Consent::all()).unwrap();
+    assert_eq!(info.publisher.as_deref(), Some("acme"));
+    assert_eq!(f.host.market_plugins()[0].installed.as_deref(), Some("1.0.0"));
+
+    // A changed file breaks the signature: refused.
+    let tampered = f.host.download_market_plugin("acme.hello").unwrap();
+    let manifest = std::fs::read_to_string(tampered.join("plugin.toml")).unwrap();
+    std::fs::write(tampered.join("plugin.toml"), manifest.replace("Sample plugin", "Totally safe plugin")).unwrap();
+    let err = f.host.preview_install(&tampered).unwrap_err();
+    assert!(err.message.contains("changed after signing"), "{}", err.message);
+
+    // Someone else's key, or another publisher's prefix: not trusted.
+    let stranger = PublisherKey::from_seed([4; 32]);
+    let (foreign, _) = signed_hello(&f.work, "1.0.1", &stranger, &f.host);
+    let unpacked = f.host.unpack_package(&foreign).unwrap();
+    assert!(f.host.preview_install(&unpacked).unwrap_err().message.contains("not one of"));
+
+    // The index revokes the installed version: disabled, the user told.
+    f.events.lock().clear();
+    let revoked =
+        vec![Revocation { id: "acme.hello".into(), versions: vec!["1.0.0".into()], reason: "steals tokens".into() }];
+    write_index(&market, &key, vec![entry.clone()], revoked, false);
+    f.host.refresh_market().unwrap();
+    let info = f.host.info_of("acme.hello").unwrap();
+    assert_eq!((info.status, info.error.as_deref()), (PluginStatus::Failed, Some("revoked: steals tokens")));
+    assert!(
+        f.events
+            .lock()
+            .iter()
+            .any(|e| matches!(e, PluginEvent::Notification { body, .. } if body.contains("steals tokens")))
+    );
+    assert!(f.host.market_plugins().is_empty(), "revoked versions are not offered");
+    assert!(f.host.install_from_dir(&dir, &Consent::all()).is_err(), "nor installable");
+    f.host.set_enabled("acme.hello", true).unwrap();
+    assert_eq!(f.host.info_of("acme.hello").unwrap().status, PluginStatus::Failed, "enabling doesn't bring it back");
+
+    // Revocations hold across restarts (the index is kept).
+    let again = PluginHost::new(f.plugins_dir.clone(), Arc::new(|_: Option<&str>, _| {}), Limits::default()).unwrap();
+    again.load_all();
+    assert_eq!(again.info_of("acme.hello").unwrap().status, PluginStatus::Failed);
+
+    // A revoked signing key disables what it signed.
+    write_index(&market, &key, vec![entry.clone()], vec![], true);
+    f.host.refresh_market().unwrap();
+    let info = f.host.info_of("acme.hello").unwrap();
+    assert!(info.error.as_deref().unwrap_or("").contains("signing key was revoked"), "{:?}", info.error);
+
+    // Lifted: it runs again.
+    write_index(&market, &key, vec![entry], vec![], false);
+    f.host.refresh_market().unwrap();
+    let info = f.host.info_of("acme.hello").unwrap();
+    assert_eq!((info.status, info.error), (PluginStatus::Inactive, None));
+}
+
+#[test]
+fn package_files_install_from_disk_unsigned() {
+    let f = fixture();
+    let src = variant(&misbehave(), &f.work, "pkg", |t| t.to_owned());
+    let files = f.host.package_files_of(&src).unwrap();
+    let out = f.work.join("misbehave-0.0.2.oiplugin");
+    package::pack(&src, &files, &out, None).unwrap();
+    let dir = f.host.unpack_package(&out).unwrap();
+    let preview = f.host.preview_install(&dir).unwrap();
+    assert_eq!((preview.unsigned, preview.publisher), (true, None));
+    let info = f.host.install_from_dir(&dir, &Consent::all()).unwrap();
+    assert_eq!((info.status, info.publisher), (PluginStatus::Inactive, None));
+}

crates/ide-host/tests/remote_plugins.rs

@@ -0,0 +1,304 @@
+//! Code plugins of a remote project run on the
+//! server. The desktop's plugin host syncs its live
+//! code plugins over the remote protocol; Checkstyle then checks the file on
+//! the server's disk when it is saved, and secrets come from the desktop.
+
+#![cfg(unix)]
+
+use ide_core::IdeEvent;
+use ide_host::plugins::remote_host::{
+    EVENT_NOTIFICATION, PackageSyncReport, PluginEventMessage, RemotePlugins, SECRET_REQUEST, SYNC_PACKAGES,
+    SecretRequest,
+};
+use ide_host::plugins::{Consent, PluginEvent, PluginHost, PluginStatus, WorkbenchEvent};
+use ide_host::rpc::{self, Dispatcher, EventMessage, Invoke};
+use ide_host::{Host, HostConfig};
+use ide_jsonrpc::{Handler, Peer};
+use ide_plugin::Limits;
+use parking_lot::Mutex;
+use serde_json::{Value, json};
+use std::os::unix::fs::PermissionsExt;
+use std::path::{Path, PathBuf};
+use std::sync::{Arc, OnceLock};
+use std::time::Duration;
+
+#[derive(Default)]
+struct Client {
+    events: Mutex<Vec<EventMessage>>,
+    plugin_events: Mutex<Vec<PluginEventMessage>>,
+    secret_requests: Mutex<Vec<SecretRequest>>,
+}
+
+impl Handler for Client {
+    fn on_notification(&self, method: &str, params: Value) {
+        match method {
+            "event" => self.events.lock().push(serde_json::from_value(params).unwrap()),
+            EVENT_NOTIFICATION => self.plugin_events.lock().push(serde_json::from_value(params).unwrap()),
+            _ => {}
+        }
+    }
+
+    fn on_request(&self, method: &str, params: Value) -> Result<Value, (i64, String)> {
+        if method == SECRET_REQUEST {
+            let r: SecretRequest = serde_json::from_value(params).unwrap();
+            let value = (r.name == "api-key").then(|| "sk-desktop".to_owned());
+            self.secret_requests.lock().push(r);
+            return Ok(serde_json::to_value(value).unwrap());
+        }
+        Err((ide_jsonrpc::codes::METHOD_NOT_FOUND, method.to_owned()))
+    }
+}
+
+async fn invoke(peer: &Peer, cmd: &str, args: Value) -> Result<Value, ide_core::IdeError> {
+    let call = Invoke { window: "main".into(), cmd: cmd.into(), args };
+    peer.request::<_, Value>("invoke", call, None).await.map_err(rpc::error_from_reply)
+}
+
+async fn sync(peer: &Peer, desktop: &PluginHost, files: &[&str]) -> PackageSyncReport {
+    let files: serde_json::Map<String, Value> = files
+        .iter()
+        .map(|id| ((*id).to_owned(), serde_json::to_value(desktop.remote_package_files(id).unwrap()).unwrap()))
+        .collect();
+    let args = json!({ "packages": desktop.remote_packages(), "files": files });
+    serde_json::from_value(invoke(peer, SYNC_PACKAGES, args).await.unwrap()).unwrap()
+}
+
+fn official(name: &str) -> PathBuf {
+    Path::new(env!("CARGO_MANIFEST_DIR")).join("../../plugins/official").join(name)
+}
+
+/// A test fixture plugin (`crates/ide-plugin/tests/fixtures/<name>`).
+fn fixture(name: &str) -> PathBuf {
+    Path::new(env!("CARGO_MANIFEST_DIR")).join("../ide-plugin/tests/fixtures").join(name)
+}
+
+/// A `checkstyle` that reports a tab on line 2 of the file it is given.
+fn fake_checkstyle(bin: &Path) {
+    std::fs::create_dir_all(bin).unwrap();
+    std::fs::write(
+        bin.join("checkstyle"),
+        "#!/bin/sh\nfor a; do file=\"$a\"; done\ngrep -q '\t' \"$file\" || { echo '<checkstyle/>'; exit 0; }\n\
+         echo '<?xml version=\"1.0\"?><checkstyle><file name=\"'\"$file\"'\">'\n\
+         echo '<error line=\"2\" column=\"1\" severity=\"warning\" message=\"Line contains a tab character.\" source=\"com.puppycrawl.tools.checkstyle.checks.whitespace.FileTabCharacterCheck\"/>'\n\
+         echo '</file></checkstyle>'\nexit 1\n",
+    )
+    .unwrap();
+    std::fs::set_permissions(bin.join("checkstyle"), std::fs::Permissions::from_mode(0o755)).unwrap();
+}
+
+async fn until(what: &str, secs: u64, mut done: impl FnMut() -> bool) {
+    for _ in 0..secs * 50 {
+        if done() {
+            return;
+        }
+        tokio::time::sleep(Duration::from_millis(20)).await;
+    }
+    panic!("timed out waiting for {what}");
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+async fn remote_projects_run_the_desktops_code_plugins_on_the_server() {
+    let tmp = tempfile::tempdir().unwrap();
+    let bin = tmp.path().join("bin");
+    fake_checkstyle(&bin);
+    let path_var = {
+        let bin = bin.clone();
+        Arc::new(move || Some(bin.clone().into_os_string()))
+    };
+
+    // The desktop: Checkstyle and AI Completion installed and granted.
+    let desktop =
+        PluginHost::new(tmp.path().join("desktop/plugins"), Arc::new(|_: Option<&str>, _| {}), Limits::default())
+            .unwrap();
+    desktop.set_program_path(path_var.clone());
+    for name in ["checkstyle", "ai-completion"] {
+        let info = desktop.install_from_dir(&official(name), &Consent::all()).unwrap();
+        assert_eq!(info.status, PluginStatus::Inactive, "{:?}", info.error);
+    }
+
+    // The server, with the project on "its" disk.
+    // Canonical, as the UI reports paths (macOS: /var → /private/var).
+    let project = tmp.path().join("remote/demo");
+    std::fs::create_dir_all(project.join("src")).unwrap();
+    let project = std::fs::canonicalize(project).unwrap();
+    let base = tmp.path().join("server");
+    let peer_slot = Arc::new(OnceLock::new());
+    let sink_peer = peer_slot.clone();
+    let host = Arc::new(Host::new(HostConfig {
+        config_dir: base.join("config"),
+        data_dir: base.join("data"),
+        local_data_dir: base.join("data"),
+        languages: Arc::new(ide_language::LanguageRegistry::load(None).unwrap()),
+        syntax: Arc::default(),
+        sink_for: Box::new(move |w| rpc::event_sink(sink_peer.clone(), Some(w.to_owned()))),
+        owner: |w| w,
+        runtime: tokio::runtime::Handle::current(),
+        project_environment: false,
+    }));
+    let plugins = RemotePlugins::start(&base.join("data"), &host, peer_slot.clone()).unwrap();
+    plugins.host().set_program_path(path_var);
+    let mut dispatcher = Dispatcher::standard();
+    plugins.register(&mut dispatcher);
+    let (client_io, server_io) = tokio::io::duplex(1 << 20);
+    let (sr, sw) = tokio::io::split(server_io);
+    tokio::spawn(rpc::serve(host.clone(), dispatcher, peer_slot, sr, sw));
+    let (cr, cw) = tokio::io::split(client_io);
+    let client = Arc::new(Client::default());
+    let peer = Peer::connect(cr, cw, client.clone());
+    let _: Value = peer.request("initialize", json!({ "version": rpc::PROTOCOL_VERSION }), None).await.unwrap();
+    invoke(&peer, "open_project", json!({ "path": project })).await.unwrap();
+    invoke(&peer, "project_trust_set", json!({ "path": project, "trusted": true, "folder": false })).await.unwrap();
+
+    // Digests first; then the files of what the server lacks; then nothing to do.
+    let first = sync(&peer, &desktop, &[]).await;
+    assert_eq!(first.missing, ["openidea.ai-completion", "openidea.checkstyle"], "{first:?}");
+    let second = sync(&peer, &desktop, &["openidea.ai-completion", "openidea.checkstyle"]).await;
+    assert_eq!(second.installed.len(), 2, "{second:?}");
+    assert!(second.failed.is_empty(), "{second:?}");
+    assert_eq!(sync(&peer, &desktop, &[]).await, PackageSyncReport::default());
+    let remote = plugins.host().info_of("openidea.checkstyle").unwrap();
+    assert_eq!(remote.status, PluginStatus::Inactive, "{:?}", remote.error);
+    assert!(remote.capabilities.iter().any(|c| c.id == "process:checkstyle" && c.granted));
+
+    // The remote window's UI routes the run-time commands to the server.
+    let kinds = invoke(&peer, "plugin_event_kinds", json!({})).await.unwrap();
+    assert!(kinds.as_array().unwrap().contains(&json!("file-saved")), "{kinds}");
+
+    // Saving a file that exists only on the server: Checkstyle reads that file.
+    let java = project.join("src/A.java");
+    std::fs::write(&java, "class A {\n\tint x;\n}\n").unwrap();
+    let saved = WorkbenchEvent::FileSaved(java.to_string_lossy().into_owned());
+    invoke(&peer, "plugin_post_events", json!({ "events": [saved] })).await.unwrap();
+    let published = || {
+        client.events.lock().iter().find_map(|m| match &m.event {
+            IdeEvent::Diagnostics { path, source, items } if source == "plugin:openidea.checkstyle" => {
+                Some((path.0.clone(), items.clone()))
+            }
+            _ => None,
+        })
+    };
+    until("remote checkstyle diagnostics", 20, || published().is_some()).await;
+    let (path, items) = published().unwrap();
+    assert_eq!(path, java);
+    assert_eq!((items.len(), items[0].range.start.line), (1, 1));
+
+    // Secrets stay on the desktop: the server asks for them when used.
+    let secrets = plugins.host().secrets("openidea.ai-completion").unwrap();
+    assert_eq!(secrets, [("api-key".to_owned(), true)]);
+    assert_eq!(client.secret_requests.lock()[0].plugin, "openidea.ai-completion");
+
+    // A command of a remote plugin, with this window as its client.
+    invoke(
+        &peer,
+        "plugin_run_command",
+        json!({ "pluginId": "openidea.ai-completion", "commandId": "toggle", "arg": null, "editor": null }),
+    )
+    .await
+    .unwrap();
+    until("the command's notification", 5, || {
+        client
+            .plugin_events
+            .lock()
+            .iter()
+            .any(|m| m.window.as_deref() == Some("main") && matches!(m.event, PluginEvent::Notification { .. }))
+    })
+    .await;
+
+    // Disabled on the desktop: gone from the server.
+    desktop.set_enabled("openidea.checkstyle", false).unwrap();
+    let removed = sync(&peer, &desktop, &[]).await;
+    assert_eq!(removed.removed, ["openidea.checkstyle"]);
+    assert!(plugins.host().info_of("openidea.checkstyle").is_err());
+    plugins.host().shutdown();
+}
+
+/// CSV Editor and a tool window with a terminal (the `jobs` fixture) in a
+/// remote project. The table edits the document on the server; the jobs are
+/// the server's `jobs` program's, and the terminal opens in the remote window.
+#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+async fn remote_projects_get_plugin_views_and_custom_editors() {
+    let tmp = tempfile::tempdir().unwrap();
+    let bin = tmp.path().join("bin");
+    std::fs::create_dir_all(&bin).unwrap();
+    std::fs::write(bin.join("jobs"), "#!/bin/sh\n[ \"$1\" = list ] && echo remote-job\n").unwrap();
+    std::fs::set_permissions(bin.join("jobs"), std::fs::Permissions::from_mode(0o755)).unwrap();
+    let path_var = {
+        let bin = bin.clone();
+        Arc::new(move || Some(bin.clone().into_os_string()))
+    };
+    let desktop =
+        PluginHost::new(tmp.path().join("desktop/plugins"), Arc::new(|_: Option<&str>, _| {}), Limits::default())
+            .unwrap();
+    desktop.set_program_path(path_var.clone());
+    for dir in [official("csv-editor"), fixture("jobs")] {
+        let info = desktop.install_from_dir(&dir, &Consent::all()).unwrap();
+        assert_eq!(info.status, PluginStatus::Inactive, "{:?}", info.error);
+    }
+
+    let project = tmp.path().join("remote/demo");
+    std::fs::create_dir_all(&project).unwrap();
+    let project = std::fs::canonicalize(project).unwrap();
+    std::fs::write(project.join("people.csv"), "name,city\nAda,London\n").unwrap();
+    let base = tmp.path().join("server");
+    let peer_slot = Arc::new(OnceLock::new());
+    let sink_peer = peer_slot.clone();
+    let host = Arc::new(Host::new(HostConfig {
+        config_dir: base.join("config"),
+        data_dir: base.join("data"),
+        local_data_dir: base.join("data"),
+        languages: Arc::new(ide_language::LanguageRegistry::load(None).unwrap()),
+        syntax: Arc::default(),
+        sink_for: Box::new(move |w| rpc::event_sink(sink_peer.clone(), Some(w.to_owned()))),
+        owner: |w| w,
+        runtime: tokio::runtime::Handle::current(),
+        project_environment: false,
+    }));
+    let plugins = RemotePlugins::start(&base.join("data"), &host, peer_slot.clone()).unwrap();
+    plugins.host().set_program_path(path_var);
+    let mut dispatcher = Dispatcher::standard();
+    plugins.register(&mut dispatcher);
+    let (client_io, server_io) = tokio::io::duplex(1 << 20);
+    let (sr, sw) = tokio::io::split(server_io);
+    tokio::spawn(rpc::serve(host.clone(), dispatcher, peer_slot, sr, sw));
+    let (cr, cw) = tokio::io::split(client_io);
+    let client = Arc::new(Client::default());
+    let peer = Peer::connect(cr, cw, client.clone());
+    let _: Value = peer.request("initialize", json!({ "version": rpc::PROTOCOL_VERSION }), None).await.unwrap();
+    invoke(&peer, "open_project", json!({ "path": project })).await.unwrap();
+    invoke(&peer, "project_trust_set", json!({ "path": project, "trusted": true, "folder": false })).await.unwrap();
+    let report = sync(&peer, &desktop, &["openidea.csv-editor", "jobs"]).await;
+    assert_eq!(report.installed.len(), 2, "{report:?}");
+
+    // CSV Editor: the document is the server's.
+    let opened = invoke(&peer, "doc_open", json!({ "path": project.join("people.csv") })).await.unwrap();
+    let doc = opened["id"].as_u64().expect("doc id");
+    let args = |extra: Value| {
+        let mut a = json!({ "pluginId": "openidea.csv-editor", "view": "table", "doc": doc });
+        a.as_object_mut().unwrap().extend(extra.as_object().unwrap().clone());
+        a
+    };
+    let view =
+        invoke(&peer, "plugin_view_render", args(json!({ "viewport": { "firstRow": 0, "rows": 50 } }))).await.unwrap();
+    assert_eq!(view["body"]["kind"], "table");
+    assert_eq!(view["body"]["value"]["rows"], json!([["Ada", "London"]]));
+    let cell = json!({ "event": { "kind": "cell", "row": 0, "column": 1, "value": "Oslo" } });
+    invoke(&peer, "plugin_view_event", args(cell)).await.unwrap();
+    let snap = invoke(&peer, "doc_snapshot", json!({ "doc": doc })).await.unwrap();
+    assert_eq!(snap["text"], "name,city\nAda,Oslo\n");
+
+    // Jobs: the server's program; the terminal opens in this window.
+    let jobs = |event: Value| json!({ "pluginId": "jobs", "view": "jobs", "doc": null, "event": event });
+    let view =
+        invoke(&peer, "plugin_view_render", json!({ "pluginId": "jobs", "view": "jobs", "doc": null })).await.unwrap();
+    assert_eq!(view["body"]["value"][0]["label"], "remote-job", "{view}");
+    invoke(&peer, "plugin_view_event", jobs(json!({ "kind": "select", "key": "remote-job" }))).await.unwrap();
+    invoke(&peer, "plugin_view_event", jobs(json!({ "kind": "button", "id": "follow" }))).await.unwrap();
+    until("the job's terminal", 5, || {
+        client.plugin_events.lock().iter().any(|m| {
+            m.window.as_deref() == Some("main")
+                && matches!(&m.event, PluginEvent::OpenTerminal { program, .. } if program.0.starts_with(bin.canonicalize().unwrap()))
+        })
+    })
+    .await;
+    plugins.host().shutdown();
+}

crates/ide-host/tests/rpc.rs

@@ -218,6 +218,13 @@ async fn serves_projects_files_documents_search_and_runs() {
     invoke(&peer, "vcs_init", json!({ "dir": project })).await.unwrap();
     until("git repository", || project.join(".git").is_dir()).await;
 
+    // A Docker run configuration's environment comes from the host its command runs on.
+    let env =
+        invoke(&peer, "docker_run_env", json!({ "endpoint": { "kind": "socket", "path": "/run/user/1/docker.sock" } }))
+            .await
+            .unwrap();
+    assert_eq!(env["DOCKER_HOST"], "unix:///run/user/1/docker.sock");
+
     // Real project-host ignore writes travel through the remote command dispatcher.
     assert!(Dispatcher::standard().commands().contains(&"vcs_add_to_ignore"));
     let ignore_root = dunce::canonicalize(&project).unwrap();

crates/ide-http/src/client.rs

@@ -35,8 +35,16 @@ pub fn build(proxy: &ProxySettings) -> IdeResult<reqwest::Client> {
         .with_platform_verifier()
         .map_err(|e| fail(e.to_string()))?
         .with_no_client_auth();
+    // `localhost` is tried on IPv4 first: local servers (Ollama, dev servers)
+    // usually listen there, and on Windows a refused `::1` costs ~2 s before
+    // the system resolver's order falls back. Ports come from the URL.
+    let loopback = [
+        std::net::SocketAddr::from((std::net::Ipv4Addr::LOCALHOST, 0)),
+        std::net::SocketAddr::from((std::net::Ipv6Addr::LOCALHOST, 0)),
+    ];
     let builder = reqwest::Client::builder()
         .tls_backend_preconfigured(tls)
+        .resolve_to_addrs("localhost", &loopback)
         .connect_timeout(Duration::from_secs(30))
         .user_agent(concat!("OpenIDEA-HttpClient/", env!("CARGO_PKG_VERSION")));
     with_proxy(builder, proxy).build().map_err(|e| fail(e.to_string()))
@@ -113,7 +121,11 @@ mod tests {
 
     /// A one-shot HTTP server on loopback: answers `200` and hands back the request head.
     fn server() -> (u16, std::thread::JoinHandle<String>) {
-        let listener = TcpListener::bind("127.0.0.1:0").unwrap();
+        server_on("127.0.0.1:0")
+    }
+
+    fn server_on(addr: &str) -> (u16, std::thread::JoinHandle<String>) {
+        let listener = TcpListener::bind(addr).unwrap();
         let port = listener.local_addr().unwrap().port();
         let handle = std::thread::spawn(move || {
             let (stream, _) = listener.accept().unwrap();
@@ -141,6 +153,21 @@ mod tests {
         check_connection(proxy, url, &CancellationToken::new()).await
     }
 
+    /// `localhost` reaches a server on either loopback address.
+    #[tokio::test]
+    async fn localhost_reaches_ipv4_and_ipv6_servers() {
+        let direct = ProxySettings::default();
+        let (port, v4) = server();
+        assert_eq!(get(&direct, &format!("http://localhost:{port}/")).await.unwrap(), "200 OK");
+        v4.join().unwrap();
+        // Hosts without IPv6 loopback skip this half.
+        if TcpListener::bind("[::1]:0").is_ok() {
+            let (port, v6) = server_on("[::1]:0");
+            assert_eq!(get(&direct, &format!("http://localhost:{port}/")).await.unwrap(), "200 OK");
+            v6.join().unwrap();
+        }
+    }
+
     #[tokio::test]
     async fn builds_for_every_mode() {
         for mode in [ProxyMode::None, ProxyMode::Auto, ProxyMode::Manual] {

crates/ide-language/Cargo.toml

@@ -7,6 +7,7 @@ license.workspace = true
 
 [dependencies]
 ide-core.workspace = true
+ide-extension.workspace = true
 ide-text.workspace = true
 serde.workspace = true
 serde_json.workspace = true

crates/ide-language/src/lib.rs

@@ -8,16 +8,20 @@ use ide_core::{LanguageId, Range, SymbolKind};
 use serde::{Deserialize, Serialize};
 use specta::Type;
 use std::collections::BTreeMap;
+use std::path::{Path, PathBuf};
 
 mod markers;
+pub mod plugin_point;
 mod registry;
 mod syntax;
 pub use markers::marked_root;
+pub use plugin_point::PluginLanguages;
 pub use registry::{FileTypes, LanguageRegistry};
 pub use syntax::{
-    CSS_CLASS, CSS_ID, CSS_VARIABLE, ConfigurationKey, FileReference, Literal, LiteralKind, MAX_CACHED_TREES,
-    MAX_PARSE_BYTES, ParsedTree, SpellingKind, SpellingRegion, Syntax, SyntaxCache, SyntaxCacheStats,
-    SyntaxHighlightKind, SyntaxHighlights, TreeError, WebReference, WebReferenceKind, merge_visibility,
+    CSS_CLASS, CSS_ID, CSS_VARIABLE, ConfigurationKey, ExternalFold, ExternalSymbol, ExternalSyntax, ExternalToken,
+    FileReference, Literal, LiteralKind, MAX_CACHED_TREES, MAX_PARSE_BYTES, ParsedTree, SpellingKind, SpellingRegion,
+    Syntax, SyntaxCache, SyntaxCacheStats, SyntaxHighlightKind, SyntaxHighlights, TreeError, WebReference,
+    WebReferenceKind, merge_visibility, set_external_syntax,
 };
 
 /// Parsed form of `languages/<id>.toml`. Backend-only; the UI gets [`LanguageInfo`].
@@ -127,6 +131,16 @@ pub struct LanguageServerConfig {
     /// basedpyright): only used while none of those is installed.
     #[serde(default)]
     pub fallback: bool,
+    /// What the server is used for (`completion`, `code-action`, `diagnostics`,
+    /// … `FEATURES` in `ide-lsp/src/caps.rs`); empty means everything. The other
+    /// capabilities it announces are ignored, so a refactoring-only server next
+    /// to the language's own one adds no completion, hover or formatting.
+    #[serde(default)]
+    pub features: Vec<String>,
+    /// Code action kinds kept from the server, matched like LSP's `only`
+    /// (`refactor` keeps `refactor.extract`); empty keeps every kind.
+    #[serde(default)]
+    pub code_action_kinds: Vec<String>,
     /// Newest Java release the server runs on (kotlin-language-server: 21). A
     /// newer `JAVA_HOME` is replaced by the newest installed JDK that fits.
     #[serde(default)]
@@ -138,6 +152,9 @@ pub struct LanguageServerConfig {
     /// Register source files with tsserver when no project configuration exists.
     #[serde(default)]
     pub tsserver_project: bool,
+    /// Set on plugin languages: start exactly this approved program.
+    #[serde(skip)]
+    pub pinned: Option<ProgramPin>,
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -157,6 +174,41 @@ pub struct DebuggerConfig {
     pub connect: Option<String>,
     #[serde(default)]
     pub install_hint: Option<String>,
+    /// Set on plugin languages: start exactly this approved program.
+    #[serde(skip)]
+    pub pinned: Option<ProgramPin>,
+}
+
+/// The program a plugin's `process:` grant approved:
+/// a plugin language's server or debug adapter starts from this exact path,
+/// and only while the file still has the approved content. Set by the plugin
+/// host, never read from a definition.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct ProgramPin {
+    pub path: PathBuf,
+    /// blake3 of the file when approved.
+    pub hash: String,
+}
+
+impl ProgramPin {
+    /// Approves `path` as it is now.
+    pub fn approve(path: impl Into<PathBuf>) -> std::io::Result<Self> {
+        let path = path.into();
+        let hash = ide_extension::ledger::file_hash(&path)?;
+        Ok(Self { path, hash })
+    }
+
+    /// Checks the file right before it is started; the error tells the user what to do.
+    pub fn verify(&self) -> Result<&Path, String> {
+        match ide_extension::ledger::file_hash(&self.path) {
+            Ok(hash) if hash == self.hash => Ok(&self.path),
+            Ok(_) => Err(format!(
+                "{} changed since it was approved; review the plugin's permissions in Settings › Plugins",
+                self.path.display()
+            )),
+            Err(e) => Err(format!("{}: {e}", self.path.display())),
+        }
+    }
 }
 
 fn default_transport() -> String {

crates/ide-language/src/plugin_point.rs

@@ -0,0 +1,294 @@
+//! The `languages` extension point: language definitions contributed by
+//! plugins, in the same format as `languages/<id>.toml`.
+//!
+//! ```toml
+//! [[contributes.languages]]
+//! path = "languages/solidity.toml"
+//! ```
+//!
+//! A definition that starts programs (`language-servers.command`,
+//! `debugger.command`) needs `process:<program>` for each: a declaration is a
+//! capability too, or registering languages would bypass the sandbox.
+//! Committed definitions live in [`PluginLanguages`], an overlay over the
+//! built-in registry (built-in definitions win on id clashes): see
+//! [`crate::LanguageRegistry::attach_plugins`]. A server or debugger whose
+//! program is not granted is left out; the language itself still works.
+
+use crate::{LanguageConfig, ProgramPin};
+use ide_extension::{Capability, Disposable, ExtensionPoint, Package, Placement, Prepared, decode};
+use parking_lot::RwLock;
+use serde::Deserialize;
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+pub const POINT_ID: &str = "languages";
+
+/// Decides whether a plugin may start a program: the approved file for a
+/// granted `process:` capability, or `None`.
+pub type ProcessPolicy = dyn Fn(&str, &Capability) -> Option<ProgramPin> + Send + Sync;
+
+/// Languages of enabled plugins, in commit order.
+#[derive(Default)]
+pub struct PluginLanguages {
+    items: RwLock<Vec<(u64, String, LanguageConfig)>>,
+    seq: AtomicU64,
+    revision: AtomicU64,
+    policy: RwLock<Option<Arc<ProcessPolicy>>>,
+}
+
+impl PluginLanguages {
+    pub fn new() -> Arc<Self> {
+        Arc::new(Self::default())
+    }
+
+    pub fn all(&self) -> Vec<LanguageConfig> {
+        self.items.read().iter().map(|(_, _, c)| c.clone()).collect()
+    }
+
+    /// `(plugin id, definition)` pairs.
+    pub fn with_owners(&self) -> Vec<(String, LanguageConfig)> {
+        self.items.read().iter().map(|(_, p, c)| (p.clone(), c.clone())).collect()
+    }
+
+    /// The plugin that contributes language `id`.
+    pub fn owner_of(&self, id: &ide_core::LanguageId) -> Option<String> {
+        self.items.read().iter().find(|(_, _, c)| &c.id == id).map(|(_, p, _)| p.clone())
+    }
+
+    /// Changes whenever [`effective`](Self::effective) may give something else.
+    pub fn revision(&self) -> u64 {
+        self.revision.load(Ordering::Acquire)
+    }
+
+    /// Who may start what. Without a policy no plugin program starts.
+    pub fn set_process_policy(&self, policy: Arc<ProcessPolicy>) {
+        *self.policy.write() = Some(policy);
+        self.invalidate();
+    }
+
+    /// Grants changed: registries recompute [`effective`](Self::effective).
+    pub fn invalidate(&self) {
+        self.revision.fetch_add(1, Ordering::Release);
+    }
+
+    /// The definitions as they take effect: servers and the debugger whose
+    /// program is granted are pinned to the approved file, the others are
+    /// left out.
+    pub fn effective(&self) -> Vec<LanguageConfig> {
+        let policy = self.policy.read().clone();
+        let pin = |plugin: &str, program: &str| {
+            policy.as_ref().and_then(|p| p(plugin, &Capability::Process(program.to_owned())))
+        };
+        self.items
+            .read()
+            .iter()
+            .map(|(_, plugin, cfg)| {
+                let mut cfg = cfg.clone();
+                cfg.language_servers.retain_mut(|s| {
+                    s.pinned = pin(plugin, &s.command);
+                    s.pinned.is_some()
+                });
+                let debugger_pin = cfg.debugger.as_ref().and_then(|d| pin(plugin, &d.command));
+                match (&mut cfg.debugger, debugger_pin) {
+                    (Some(d), Some(p)) => d.pinned = Some(p),
+                    (debugger, _) => *debugger = None,
+                }
+                cfg
+            })
+            .collect()
+    }
+
+    /// Adds a definition until the returned handle is dropped.
+    pub fn add(self: &Arc<Self>, plugin: String, cfg: LanguageConfig) -> Disposable {
+        let seq = self.seq.fetch_add(1, Ordering::Relaxed);
+        self.items.write().push((seq, plugin, cfg));
+        self.revision.fetch_add(1, Ordering::Release);
+        let weak = Arc::downgrade(self);
+        Disposable::new(move || {
+            if let Some(this) = weak.upgrade() {
+                this.items.write().retain(|(s, _, _)| *s != seq);
+                this.revision.fetch_add(1, Ordering::Release);
+            }
+        })
+    }
+}
+
+pub struct LanguagesPoint {
+    store: Arc<PluginLanguages>,
+}
+
+impl LanguagesPoint {
+    pub fn new(store: Arc<PluginLanguages>) -> Self {
+        Self { store }
+    }
+}
+
+#[derive(Deserialize)]
+#[serde(deny_unknown_fields)]
+struct Decl {
+    /// A `languages/<id>.toml`-style file in the package.
+    path: PathBuf,
+}
+
+/// Parses and checks one language definition.
+pub fn parse_definition(src: &str) -> Result<LanguageConfig, String> {
+    let cfg: LanguageConfig = toml::from_str(src).map_err(|e| format!("invalid language definition: {e}"))?;
+    validate_definition(&cfg)?;
+    Ok(cfg)
+}
+
+/// Checks a definition that did not come from a package file (a remote sync).
+pub fn validate_definition(cfg: &LanguageConfig) -> Result<(), String> {
+    let id = cfg.id.as_str();
+    if id.is_empty() || cfg.name.trim().is_empty() {
+        return Err("language `id` and `name` must not be empty".into());
+    }
+    if !id.chars().all(|c| c.is_ascii_alphanumeric() || matches!(c, '-' | '_' | '.' | '+')) || id.len() > 64 {
+        return Err(format!("invalid language id {id:?}"));
+    }
+    if let Some(first) = &cfg.first_line {
+        regex_lite::Regex::new(first).map_err(|e| format!("invalid first-line pattern: {e}"))?;
+    }
+    Ok(())
+}
+
+/// The programs a definition starts, as `process:` capabilities.
+pub fn required_capabilities(cfg: &LanguageConfig) -> Vec<Capability> {
+    let mut caps: Vec<Capability> = Vec::new();
+    let servers = cfg.language_servers.iter().map(|s| s.command.as_str());
+    for program in servers.chain(cfg.debugger.iter().map(|d| d.command.as_str())) {
+        let cap = Capability::Process(program.to_owned());
+        if !program.trim().is_empty() && !caps.contains(&cap) {
+            caps.push(cap);
+        }
+    }
+    caps
+}
+
+impl ExtensionPoint for LanguagesPoint {
+    fn id(&self) -> &'static str {
+        POINT_ID
+    }
+
+    fn placement(&self) -> Placement {
+        Placement::Workspace
+    }
+
+    fn prepare(&self, pkg: &Package, decl: toml::Value) -> Result<Prepared, String> {
+        let decl: Decl = decode(POINT_ID, decl)?;
+        let src = pkg.read_text(&decl.path)?;
+        let cfg = parse_definition(&src).map_err(|e| format!("{}: {e}", decl.path.display()))?;
+        let caps = required_capabilities(&cfg);
+        let (store, plugin, key, label) = (
+            self.store.clone(),
+            pkg.id().to_owned(),
+            cfg.id.to_string(),
+            format!("{} (.{})", cfg.name, cfg.extensions.join(", .")),
+        );
+        let mut prepared = Prepared::new(label, move || Ok(store.add(plugin, cfg))).key(key).file(decl.path);
+        for cap in caps {
+            prepared = prepared.capability(cap);
+        }
+        Ok(prepared)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ide_extension::{ExtensionRegistry, Manifest};
+
+    #[test]
+    fn languages_point_registers_and_requires_process_capabilities() {
+        let tmp = tempfile::tempdir().unwrap();
+        std::fs::create_dir(tmp.path().join("l")).unwrap();
+        std::fs::write(
+            tmp.path().join("l/sol.toml"),
+            "id = \"solidity\"\nname = \"Solidity\"\nextensions = [\"sol\"]\n\
+             [[language-servers]]\nname = \"solc\"\ncommand = \"solc\"\nargs = [\"--lsp\"]\n",
+        )
+        .unwrap();
+        let src = "id = \"p\"\nname = \"P\"\nversion = \"1.0.0\"\nengines.openidea = \"^1.0\"\n\
+                   [[contributes.languages]]\npath = \"l/sol.toml\"";
+        let pkg = Package::new(Manifest::parse(src).unwrap(), tmp.path().to_path_buf());
+        let store = PluginLanguages::new();
+        let reg = ExtensionRegistry::new();
+        reg.register(Arc::new(LanguagesPoint::new(store.clone()))).unwrap();
+        let set = reg.prepare(&pkg).unwrap();
+        assert_eq!(set.capabilities, [Capability::Process("solc".into())]);
+        assert_eq!(set.files, [PathBuf::from("l/sol.toml")]);
+        reg.commit(set).unwrap();
+        assert_eq!(store.all()[0].id.as_str(), "solidity");
+        reg.dispose_plugin("p");
+        assert!(store.all().is_empty());
+
+        let bad = |def: &str| parse_definition(def).unwrap_err();
+        assert!(bad("not toml [").contains("invalid language"));
+        assert!(bad("id = \"\"\nname = \"x\"").contains("must not be empty"));
+        assert!(bad("id = \"a b\"\nname = \"x\"").contains("invalid language id"));
+    }
+
+    #[test]
+    fn registry_overlay_follows_the_store_and_the_grants() {
+        use crate::LanguageRegistry;
+        use ide_core::LanguageId;
+        use std::path::Path;
+
+        let base = LanguageRegistry::load(None).unwrap();
+        let store = PluginLanguages::new();
+        base.attach_plugins(store.clone());
+        // Projects fork before plugins load: the fork follows the store anyway.
+        let project = base.fork();
+        assert_eq!(project.detect(Path::new("a.sol"), None), LanguageId::plain_text());
+
+        let sol = parse_definition(
+            "id = \"solidity\"\nname = \"Solidity\"\nextensions = [\"sol\"]\n\
+             [[language-servers]]\nname = \"solc\"\ncommand = \"solc\"\n\
+             [debugger]\nadapter = \"soldbg\"\ncommand = \"soldbg\"\n",
+        )
+        .unwrap();
+        let rust_clash = parse_definition("id = \"rust\"\nname = \"Evil Rust\"\nextensions = [\"rs\"]").unwrap();
+        let ext_clash = parse_definition(
+            "id = \"rusty\"\nname = \"Rusty\"\nextensions = [\"rs\", \"rsy\"]\nfilenames = [\"Cargo.lock\"]",
+        )
+        .unwrap();
+        let _sol = store.add("acme.sol".into(), sol);
+        let _clash = store.add("acme.evil".into(), rust_clash);
+        let _ext = store.add("acme.evil".into(), ext_clash);
+
+        assert_eq!(project.detect(Path::new("a.sol"), None).as_str(), "solidity");
+        let rust = project.get(&LanguageId::new("rust")).unwrap();
+        assert_eq!(rust.name, "Rust", "built-in definitions win on id clashes");
+        assert_eq!(project.detect(Path::new("main.rs"), None).as_str(), "rust", "and keep their extensions");
+        assert_ne!(project.detect(Path::new("Cargo.lock"), None).as_str(), "rusty", "and file names");
+        assert_eq!(project.detect(Path::new("x.rsy"), None).as_str(), "rusty");
+        // No policy: the language works, its programs do not start.
+        let cfg = project.get(&LanguageId::new("solidity")).unwrap();
+        assert!(cfg.language_servers.is_empty() && cfg.debugger.is_none());
+
+        let pin = ProgramPin { path: "/opt/solc".into(), hash: "h".into() };
+        let granted = pin.clone();
+        store.set_process_policy(Arc::new(move |plugin, cap| {
+            (plugin == "acme.sol" && *cap == Capability::Process("solc".into())).then(|| granted.clone())
+        }));
+        let cfg = project.get(&LanguageId::new("solidity")).unwrap();
+        assert_eq!(cfg.language_servers[0].pinned.as_ref(), Some(&pin));
+        assert!(cfg.debugger.is_none(), "soldbg was not granted");
+
+        drop(_sol);
+        assert_eq!(project.detect(Path::new("a.sol"), None), LanguageId::plain_text());
+        assert!(base.get(&LanguageId::new("solidity")).is_none());
+    }
+
+    #[test]
+    fn program_pins_check_the_file() {
+        let tmp = tempfile::tempdir().unwrap();
+        let bin = tmp.path().join("tool");
+        std::fs::write(&bin, "v1").unwrap();
+        let pin = ProgramPin { path: bin.clone(), hash: ide_extension::ledger::file_hash(&bin).unwrap() };
+        assert_eq!(pin.verify().unwrap(), bin);
+        std::fs::write(&bin, "v2").unwrap();
+        assert!(pin.verify().unwrap_err().contains("changed since it was approved"));
+    }
+}

crates/ide-language/src/registry.rs

@@ -1,10 +1,11 @@
 use crate::LanguageConfig;
+use crate::plugin_point::PluginLanguages;
 use ide_core::settings::{FileSettings, FileTypeAssociation};
 use ide_core::{IdeError, IdeResult, LanguageId};
 use parking_lot::RwLock;
 use std::collections::{BTreeMap, HashMap};
 use std::path::{Path, PathBuf};
-use std::sync::Arc;
+use std::sync::{Arc, OnceLock};
 
 /// Built-in definitions, embedded at compile time. Add new languages here.
 const BUILTIN: &[(&str, &str)] = &[
@@ -88,12 +89,22 @@ const BUILTIN: &[(&str, &str)] = &[
 ];
 
 pub struct LanguageRegistry {
-    languages: Vec<LanguageConfig>,
-    /// Lookup tables of the definitions with the user's file types applied.
-    tables: RwLock<Arc<Tables>>,
+    /// Built-in definitions and the user's `languages/*.toml`.
+    base: Vec<LanguageConfig>,
+    /// Languages of enabled plugins, shared by every fork; `base` wins on id clashes.
+    plugins: OnceLock<Arc<PluginLanguages>>,
+    state: RwLock<Arc<State>>,
     file_types: RwLock<FileTypes>,
 }
 
+/// The effective definitions and their lookup tables (the user's file types applied).
+struct State {
+    languages: Vec<LanguageConfig>,
+    tables: Tables,
+    /// [`PluginLanguages::revision`] they were built from.
+    plugins_revision: u64,
+}
+
 /// The user's file type associations (Settings › Editor › File Types) and
 /// per-file overrides (Override File Type), resolved for one project.
 #[derive(Clone, Debug, Default, PartialEq)]
@@ -247,12 +258,73 @@ impl LanguageRegistry {
             }
         }
         let tables = Tables::build(&languages, &FileTypes::default());
-        Self { languages, tables: RwLock::new(Arc::new(tables)), file_types: RwLock::default() }
+        let state = State { languages: languages.clone(), tables, plugins_revision: 0 };
+        Self {
+            base: languages,
+            plugins: OnceLock::new(),
+            state: RwLock::new(Arc::new(state)),
+            file_types: RwLock::default(),
+        }
+    }
+
+    /// Adds the languages of enabled plugins (once, before projects fork the
+    /// registry). They follow the store: installing, disabling or changing a
+    /// grant takes effect on the next lookup in every fork.
+    pub fn attach_plugins(&self, plugins: Arc<PluginLanguages>) {
+        if self.plugins.set(plugins).is_err() {
+            tracing::warn!("plugin languages are already attached");
+        }
     }
 
     /// A registry with the same definitions and no user file types (one per project).
     pub fn fork(&self) -> Self {
-        Self::from_configs(self.languages.clone())
+        let fork = Self::from_configs(self.base.clone());
+        if let Some(p) = self.plugins.get() {
+            let _ = fork.plugins.set(p.clone());
+        }
+        fork
+    }
+
+    /// The current effective state, rebuilt when the plugin languages changed.
+    fn state(&self) -> Arc<State> {
+        let Some(plugins) = self.plugins.get() else { return self.state.read().clone() };
+        let revision = plugins.revision();
+        {
+            let state = self.state.read();
+            if state.plugins_revision == revision {
+                return state.clone();
+            }
+        }
+        let file_types = self.file_types.read();
+        let mut state = self.state.write();
+        if state.plugins_revision != revision {
+            *state = Arc::new(self.build(&file_types, Some(revision)));
+        }
+        state.clone()
+    }
+
+    fn build(&self, file_types: &FileTypes, revision: Option<u64>) -> State {
+        let mut languages = self.base.clone();
+        let mut plugins_revision = 0;
+        if let Some(plugins) = self.plugins.get() {
+            plugins_revision = revision.unwrap_or_else(|| plugins.revision());
+            // A plugin adds languages; it can't take over a built-in or user
+            // definition's id, extensions or file names (File Types can).
+            let base_ext: std::collections::HashSet<String> =
+                self.base.iter().flat_map(|l| &l.extensions).map(|e| e.to_ascii_lowercase()).collect();
+            let base_names: std::collections::HashSet<&str> =
+                self.base.iter().flat_map(|l| &l.filenames).map(String::as_str).collect();
+            for mut cfg in plugins.effective() {
+                if languages.iter().any(|l| l.id == cfg.id) {
+                    continue;
+                }
+                cfg.extensions.retain(|e| !base_ext.contains(&e.to_ascii_lowercase()));
+                cfg.filenames.retain(|n| !base_names.contains(n.as_str()));
+                languages.push(cfg);
+            }
+        }
+        let tables = Tables::build(&languages, file_types);
+        State { languages, tables, plugins_revision }
     }
 
     /// A copy with the same definitions and file types (to compare detection before / after a change).
@@ -268,17 +340,19 @@ impl LanguageRegistry {
         if *current == file_types {
             return false;
         }
-        *self.tables.write() = Arc::new(Tables::build(&self.languages, &file_types));
+        let state = self.build(&file_types, None);
+        *self.state.write() = Arc::new(state);
         *current = file_types;
         true
     }
 
+    /// Built-in, user and plugin definitions.
     pub fn all(&self) -> Vec<LanguageConfig> {
-        self.languages.clone()
+        self.state().languages.clone()
     }
 
     pub fn get(&self, id: &LanguageId) -> Option<LanguageConfig> {
-        self.languages.iter().find(|l| &l.id == id).cloned()
+        self.state().languages.iter().find(|l| &l.id == id).cloned()
     }
 
     /// The `framework-ui-modes` mode of a `language` file at `path`: the first
@@ -286,7 +360,8 @@ impl LanguageRegistry {
     /// directory without one: loose files). `None` keeps the language's own
     /// `ui-mode`.
     pub fn framework_ui_mode(&self, language: &LanguageId, path: &Path, project_root: Option<&Path>) -> Option<String> {
-        let cfg = self.languages.iter().find(|l| &l.id == language)?;
+        let state = self.state();
+        let cfg = state.languages.iter().find(|l| &l.id == language)?;
         cfg.framework_ui_modes
             .iter()
             .find(|f| crate::marked_root(project_root, path, &f.root_markers).is_some())
@@ -296,7 +371,8 @@ impl LanguageRegistry {
     /// Creating or removing `path` can change a file's `framework_ui_mode`:
     /// it is a framework's root marker.
     pub fn is_framework_marker(&self, path: &Path) -> bool {
-        self.languages
+        self.state()
+            .languages
             .iter()
             .flat_map(|l| &l.framework_ui_modes)
             .any(|f| f.root_markers.iter().any(|m| crate::markers::is_marker_path(path, m)))
@@ -307,33 +383,34 @@ impl LanguageRegistry {
     /// then hashbang / first line; falls back to plaintext. The user's patterns
     /// win over the definitions'.
     pub fn detect(&self, path: &Path, first_line: Option<&str>) -> LanguageId {
-        let t = self.tables.read().clone();
+        let state = self.state();
+        let (t, languages) = (&state.tables, &state.languages);
         if !t.overrides.is_empty()
             && let Some(&i) = t.overrides.get(path)
         {
-            return self.languages[i].id.clone();
+            return languages[i].id.clone();
         }
         let file_name = path.file_name().and_then(|n| n.to_str()).unwrap_or_default();
         if let Some(&i) = t.by_name.get(file_name) {
-            return self.languages[i].id.clone();
+            return languages[i].id.clone();
         }
         if let Some((_, i)) = t.name_globs.iter().find(|(p, _)| wildcard_match(p, file_name)) {
-            return self.languages[*i].id.clone();
+            return languages[*i].id.clone();
         }
         let lower = file_name.to_ascii_lowercase();
         let mut rest = lower.as_str();
         while let Some(dot) = rest.find('.') {
             rest = &rest[dot + 1..];
             if let Some(&i) = t.by_ext.get(rest) {
-                return self.languages[i].id.clone();
+                return languages[i].id.clone();
             }
         }
         if let Some(line) = first_line {
             if let Some((_, i)) = t.hashbangs.iter().find(|(h, _)| hashbang_runs(line, h)) {
-                return self.languages[*i].id.clone();
+                return languages[*i].id.clone();
             }
             if let Some((_, i)) = t.first_line.iter().find(|(re, _)| re.is_match(line)) {
-                return self.languages[*i].id.clone();
+                return languages[*i].id.clone();
             }
         }
         LanguageId::plain_text()

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

@@ -197,6 +197,7 @@ impl SyntaxCache {
                     let query = g.outline_query()?;
                     Some(outline::outline(g, query, tree, text))
                 })
+                .or_else(|| super::external::outline(lang, text))
             },
         )
     }
@@ -211,6 +212,7 @@ impl SyntaxCache {
                 self.with_tree(doc, lang, version, text, |g, tree, text| {
                     Some(folding::folding(g.spec, g.kinds(), tree, text, self.syntax.comment_tokens(lang)))
                 })
+                .or_else(|| super::external::folding(lang, text))
                 .or_else(|| Some(self.syntax.custom_folding(lang, text)))
             },
         )
@@ -227,6 +229,7 @@ impl SyntaxCache {
                 self.with_tree(doc, lang, version, text, |g, tree, text| {
                     Some(highlight::highlights(g.highlight_query()?, tree, text))
                 })
+                .or_else(|| super::external::highlights(lang, text))
             },
         ))
     }

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

@@ -0,0 +1,239 @@
+//! Syntax from outside this crate for languages without a built-in grammar: a
+//! plugin's `syntax-provider`. Providers return flat
+//! results in UTF-8 byte offsets; they are validated and converted here into
+//! the same [`OutlineItem`], [`FoldRange`] and highlight data the grammars
+//! produce, so the editor can't tell the difference. Results are memoized per
+//! document version by the [`super::SyntaxCache`] like the grammars' answers.
+
+use super::highlight::SyntaxHighlightKind;
+use super::lines::LineIndex;
+use crate::{FoldKind, FoldRange};
+use ide_core::{LanguageId, OutlineItem, SymbolKind};
+use parking_lot::RwLock;
+use std::sync::Arc;
+
+/// A highlighted range (UTF-8 byte offsets); `kind` is a kebab-case
+/// [`SyntaxHighlightKind`] name.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct ExternalToken {
+    pub start: u32,
+    pub end: u32,
+    pub kind: String,
+}
+
+/// A structure-view symbol (UTF-8 byte offsets); `parent` indexes an earlier
+/// symbol of the same list.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct ExternalSymbol {
+    pub name: String,
+    pub detail: Option<String>,
+    pub kind: String,
+    pub start: u32,
+    pub end: u32,
+    pub name_start: u32,
+    pub name_end: u32,
+    pub parent: Option<u32>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct ExternalFold {
+    pub start_line: u32,
+    pub end_line: u32,
+    pub kind: String,
+}
+
+/// Answers for languages it provides, `None` for the others.
+pub trait ExternalSyntax: Send + Sync {
+    fn highlights(&self, lang: &LanguageId, text: &str) -> Option<Vec<ExternalToken>>;
+    fn outline(&self, lang: &LanguageId, text: &str) -> Option<Vec<ExternalSymbol>>;
+    fn folding(&self, lang: &LanguageId, text: &str) -> Option<Vec<ExternalFold>>;
+}
+
+static PROVIDER: RwLock<Option<Arc<dyn ExternalSyntax>>> = RwLock::new(None);
+
+/// Installs (or removes) the provider every project's syntax cache consults.
+pub fn set_external_syntax(provider: Option<Arc<dyn ExternalSyntax>>) {
+    *PROVIDER.write() = provider;
+}
+
+fn provider() -> Option<Arc<dyn ExternalSyntax>> {
+    PROVIDER.read().clone()
+}
+
+fn clamp(text: &str, offset: u32) -> usize {
+    let mut at = (offset as usize).min(text.len());
+    while !text.is_char_boundary(at) {
+        at -= 1;
+    }
+    at
+}
+
+/// `[from, to, kind]` triples in UTF-16 offsets, sorted and non-overlapping.
+pub(crate) fn highlights(lang: &LanguageId, text: &str) -> Option<Vec<u32>> {
+    let mut tokens = provider()?.highlights(lang, text)?;
+    tokens.sort_by_key(|t| (t.start, t.end));
+    let lines = LineIndex::new(text);
+    let mut data = Vec::with_capacity(tokens.len() * 3);
+    let mut covered = 0usize;
+    for t in tokens {
+        let Some(kind) = SyntaxHighlightKind::from_name(&t.kind) else { continue };
+        let (start, end) = (clamp(text, t.start), clamp(text, t.end));
+        if end <= start || start < covered {
+            continue;
+        }
+        covered = end;
+        let index = SyntaxHighlightKind::ALL.iter().position(|k| *k == kind).unwrap_or_default() as u32;
+        data.extend([lines.utf16_at(start) as u32, lines.utf16_at(end) as u32, index]);
+    }
+    Some(data)
+}
+
+fn symbol_kind(name: &str) -> SymbolKind {
+    let camel: String = {
+        let mut out = String::with_capacity(name.len());
+        let mut upper = false;
+        for c in name.chars() {
+            if c == '-' {
+                upper = true;
+            } else if upper {
+                out.push(c.to_ascii_uppercase());
+                upper = false;
+            } else {
+                out.push(c);
+            }
+        }
+        out
+    };
+    serde_json::from_value(serde_json::Value::String(camel)).unwrap_or(SymbolKind::Unknown)
+}
+
+pub(crate) fn outline(lang: &LanguageId, text: &str) -> Option<Vec<OutlineItem>> {
+    let symbols = provider()?.outline(lang, text)?;
+    let lines = LineIndex::new(text);
+    // Built bottom-up: children are attached to their parent (an earlier index).
+    let mut items: Vec<Option<OutlineItem>> = Vec::with_capacity(symbols.len());
+    let mut parents: Vec<Option<usize>> = Vec::with_capacity(symbols.len());
+    for (i, s) in symbols.iter().enumerate() {
+        let (start, end) = (clamp(text, s.start), clamp(text, s.end.max(s.start)));
+        let name_start = clamp(text, s.name_start).clamp(start, end);
+        let name_end = clamp(text, s.name_end).clamp(name_start, end);
+        items.push(Some(OutlineItem {
+            name: s.name.clone(),
+            detail: s.detail.clone(),
+            kind: symbol_kind(&s.kind),
+            range: lines.range(start, end),
+            selection_range: lines.range(name_start, name_end),
+            children: Vec::new(),
+            visibility: None,
+        }));
+        parents.push(s.parent.map(|p| p as usize).filter(|&p| p < i));
+    }
+    for i in (0..items.len()).rev() {
+        if let Some(p) = parents[i] {
+            let child = items[i].take().expect("each item is moved once");
+            if let Some(parent) = items[p].as_mut() {
+                parent.children.insert(0, child);
+            }
+        }
+    }
+    Some(items.into_iter().flatten().collect())
+}
+
+pub(crate) fn folding(lang: &LanguageId, text: &str) -> Option<Vec<FoldRange>> {
+    let folds = provider()?.folding(lang, text)?;
+    let last_line = LineIndex::new(text).line_of(text.len()) as u32;
+    let mut out: Vec<FoldRange> = folds
+        .into_iter()
+        .filter(|f| f.start_line < f.end_line && f.end_line <= last_line)
+        .map(|f| FoldRange {
+            start_line: f.start_line,
+            end_line: f.end_line,
+            kind: match f.kind.as_str() {
+                "comment" => FoldKind::Comment,
+                "imports" => FoldKind::Imports,
+                _ => FoldKind::Region,
+            },
+        })
+        .collect();
+    out.sort_by_key(|f| (f.start_line, std::cmp::Reverse(f.end_line)));
+    out.dedup_by_key(|f| (f.start_line, f.end_line));
+    Some(out)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    struct Fake;
+
+    impl ExternalSyntax for Fake {
+        fn highlights(&self, lang: &LanguageId, _: &str) -> Option<Vec<ExternalToken>> {
+            (lang.as_str() == "fake").then(|| {
+                vec![
+                    ExternalToken { start: 9, end: 12, kind: "keyword".into() },
+                    // "é" is 2 bytes, 1 UTF-16 unit.
+                    ExternalToken { start: 0, end: 6, kind: "string".into() },
+                    ExternalToken { start: 2, end: 4, kind: "number".into() }, // overlaps: dropped
+                    ExternalToken { start: 13, end: 14, kind: "nonsense".into() },
+                    ExternalToken { start: 7, end: 99, kind: "doc-comment".into() },
+                ]
+            })
+        }
+        fn outline(&self, lang: &LanguageId, _: &str) -> Option<Vec<ExternalSymbol>> {
+            let sym = |name: &str, kind: &str, start, end, parent| ExternalSymbol {
+                name: name.into(),
+                detail: None,
+                kind: kind.into(),
+                start,
+                end,
+                name_start: start,
+                name_end: start + 1,
+                parent,
+            };
+            (lang.as_str() == "fake").then(|| {
+                vec![
+                    sym("C", "class", 0, 14, None),
+                    sym("f", "function", 8, 12, Some(0)),
+                    sym("g", "event", 12, 13, Some(0)),
+                    sym("bad", "method", 1, 2, Some(9)),
+                ]
+            })
+        }
+        fn folding(&self, lang: &LanguageId, _: &str) -> Option<Vec<ExternalFold>> {
+            (lang.as_str() == "fake").then(|| {
+                vec![
+                    ExternalFold { start_line: 0, end_line: 1, kind: "comment".into() },
+                    ExternalFold { start_line: 1, end_line: 1, kind: "region".into() },
+                    ExternalFold { start_line: 0, end_line: 9, kind: "region".into() },
+                ]
+            })
+        }
+    }
+
+    #[test]
+    fn converts_and_validates_provider_results() {
+        set_external_syntax(Some(Arc::new(Fake)));
+        let text = "\"héllo\"\nfn x(){}";
+        let lang = LanguageId::new("fake");
+        assert!(highlights(&LanguageId::new("other"), text).is_none());
+        let data = highlights(&lang, text).unwrap();
+        let string = SyntaxHighlightKind::ALL.iter().position(|k| *k == SyntaxHighlightKind::String).unwrap() as u32;
+        let doc = SyntaxHighlightKind::ALL.iter().position(|k| *k == SyntaxHighlightKind::DocComment).unwrap() as u32;
+        // UTF-16: `"héllo"` is 7 units (bytes 0..8 → 0..7); byte 6 is inside "o\"" → 5.
+        assert_eq!(&data[..3], &[0, 5, string]);
+        assert_eq!(&data[3..], &[6, 16, doc], "clamped to the text, keyword dropped as overlapping");
+
+        let outline = outline(&lang, text).unwrap();
+        assert_eq!(outline.len(), 2, "orphan with a bad parent stays top-level");
+        assert_eq!(outline[0].kind, SymbolKind::Class);
+        assert_eq!(
+            outline[0].children.iter().map(|c| c.kind).collect::<Vec<_>>(),
+            [SymbolKind::Function, SymbolKind::Event]
+        );
+        assert_eq!(outline[1].kind, SymbolKind::Method);
+
+        let folds = folding(&lang, text).unwrap();
+        assert_eq!(folds, [FoldRange { start_line: 0, end_line: 1, kind: FoldKind::Comment }]);
+        set_external_syntax(None);
+    }
+}

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

@@ -72,6 +72,24 @@ impl SyntaxHighlightKind {
         Self::Operator,
         Self::Punctuation,
     ];
+
+    /// The kebab-case name plugins use (`doc-comment`, `function-call`, …).
+    pub fn from_name(name: &str) -> Option<Self> {
+        Self::ALL.into_iter().find(|k| {
+            let camel = serde_json::to_value(k).ok();
+            let camel = camel.as_ref().and_then(|v| v.as_str()).unwrap_or_default();
+            let mut kebab = String::with_capacity(camel.len() + 2);
+            for c in camel.chars() {
+                if c.is_ascii_uppercase() {
+                    kebab.push('-');
+                    kebab.push(c.to_ascii_lowercase());
+                } else {
+                    kebab.push(c);
+                }
+            }
+            kebab == name
+        })
+    }
 }
 
 /// Highlighted ranges of a whole document, packed like LSP semantic tokens.

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

@@ -2,6 +2,7 @@
 
 mod cache;
 mod configuration;
+mod external;
 mod folding;
 mod grammars;
 mod highlight;
@@ -14,6 +15,7 @@ mod web;
 use crate::{FoldRange, LanguageConfig, LanguageRegistry, SymbolTag};
 pub use cache::{MAX_CACHED_TREES, SyntaxCache, SyntaxCacheStats};
 pub use configuration::ConfigurationKey;
+pub use external::{ExternalFold, ExternalSymbol, ExternalSyntax, ExternalToken, set_external_syntax};
 use grammars::{SPECS, Spec};
 pub use highlight::{SyntaxHighlightKind, SyntaxHighlights};
 use ide_core::{LanguageId, OutlineItem, Pos, Range};

crates/ide-lsp/src/caps.rs

@@ -183,6 +183,8 @@ pub struct ServerCaps {
     /// `Some(include_text)` when the server wants `didSave`.
     pub save: Option<bool>,
     pub semantic_legend: Option<(Vec<String>, Vec<String>)>,
+    /// Applied to what the server announces, now and in later registrations.
+    pub restriction: Restriction,
 }
 
 /// LSP request method → server capability key, for features and dynamic registration.
@@ -215,6 +217,104 @@ pub fn capability_key(method: &str) -> Option<&'static str> {
     })
 }
 
+/// Names for a server's `features` → the capability keys each one keeps.
+pub const FEATURES: &[(&str, &[&str])] = &[
+    ("completion", &["completionProvider"]),
+    ("inline-completion", &["inlineCompletionProvider"]),
+    ("hover", &["hoverProvider"]),
+    ("signature-help", &["signatureHelpProvider"]),
+    ("definition", &["definitionProvider"]),
+    ("declaration", &["declarationProvider"]),
+    ("type-definition", &["typeDefinitionProvider"]),
+    ("implementation", &["implementationProvider"]),
+    ("references", &["referencesProvider"]),
+    ("document-highlight", &["documentHighlightProvider"]),
+    ("document-symbol", &["documentSymbolProvider"]),
+    ("workspace-symbol", &["workspaceSymbolProvider"]),
+    ("code-action", &["codeActionProvider", "executeCommandProvider"]),
+    ("code-lens", &["codeLensProvider", "executeCommandProvider"]),
+    ("rename", &["renameProvider"]),
+    (
+        "formatting",
+        &["documentFormattingProvider", "documentRangeFormattingProvider", "documentOnTypeFormattingProvider"],
+    ),
+    ("inlay-hint", &["inlayHintProvider"]),
+    ("semantic-tokens", &["semanticTokensProvider"]),
+    ("document-link", &["documentLinkProvider"]),
+    ("call-hierarchy", &["callHierarchyProvider"]),
+    ("type-hierarchy", &["typeHierarchyProvider"]),
+    ("folding-range", &["foldingRangeProvider"]),
+    ("selection-range", &["selectionRangeProvider"]),
+    ("diagnostics", &["diagnosticProvider"]),
+];
+
+/// A server's `features` and `code-action-kinds`: the part of its capabilities
+/// the IDE uses.
+#[derive(Clone, Debug, Default, PartialEq)]
+pub struct Restriction {
+    /// Allowed `*Provider` keys; `None` allows all.
+    keys: Option<Vec<&'static str>>,
+    /// Code action kind prefixes kept; empty keeps all.
+    action_kinds: Vec<String>,
+}
+
+impl Restriction {
+    /// Unknown feature names are logged and ignored.
+    pub fn new(server: &str, features: &[String], action_kinds: &[String]) -> Self {
+        let keys = (!features.is_empty()).then(|| {
+            let mut keys = Vec::new();
+            for name in features {
+                match FEATURES.iter().find(|(n, _)| n == name) {
+                    Some((_, k)) => keys.extend_from_slice(k),
+                    None => tracing::warn!("{server}: unknown feature `{name}` in `features`"),
+                }
+            }
+            keys
+        });
+        Self { keys, action_kinds: action_kinds.to_vec() }
+    }
+
+    fn allows(&self, key: &str) -> bool {
+        self.keys.as_ref().is_none_or(|k| k.contains(&key))
+    }
+
+    /// Whether the server's `publishDiagnostics` are shown.
+    pub fn diagnostics(&self) -> bool {
+        self.allows("diagnosticProvider")
+    }
+
+    /// Whether a code action of `kind` is kept; one without a kind only when
+    /// every kind is.
+    pub fn keeps_action(&self, kind: Option<&str>) -> bool {
+        self.action_kinds.is_empty() || kind.is_some_and(|k| self.action_kinds.iter().any(|p| kind_within(k, p)))
+    }
+
+    /// The kinds the server can still return: those it lists that are kept,
+    /// narrowed to the kept prefixes below them (`refactor` → `refactor.extract`).
+    fn advertised_kinds(&self, listed: Option<Vec<String>>) -> Vec<String> {
+        let Some(listed) = listed else { return self.action_kinds.clone() };
+        let mut out = Vec::new();
+        for k in &listed {
+            let narrowed: Vec<&String> = if self.keeps_action(Some(k)) {
+                vec![k]
+            } else {
+                self.action_kinds.iter().filter(|p| kind_within(p, k)).collect()
+            };
+            for k in narrowed {
+                if !out.contains(k) {
+                    out.push(k.clone());
+                }
+            }
+        }
+        out
+    }
+}
+
+/// `kind` is `prefix` or below it (`refactor.extract` within `refactor`).
+fn kind_within(kind: &str, prefix: &str) -> bool {
+    kind.strip_prefix(prefix).is_some_and(|rest| rest.is_empty() || rest.starts_with('.'))
+}
+
 fn truthy(v: Option<&Value>) -> bool {
     !matches!(v, None | Some(Value::Null) | Some(Value::Bool(false)))
 }
@@ -244,7 +344,34 @@ impl ServerCaps {
             };
             (strings("tokenTypes"), strings("tokenModifiers"))
         });
-        Self { raw, encoding, open_close, sync, save, semantic_legend }
+        Self { raw, encoding, open_close, sync, save, semantic_legend, restriction: Restriction::default() }
+    }
+
+    /// Drops the capabilities outside the server's `features`, and code action
+    /// kinds outside its `code-action-kinds`. Document sync, workspace options
+    /// and `experimental` stay.
+    pub fn restrict(&mut self, restriction: Restriction) {
+        if let Some(o) = self.raw.as_object_mut() {
+            o.retain(|key, _| !key.ends_with("Provider") || restriction.allows(key));
+        }
+        if self.has("codeActionProvider") && !restriction.action_kinds.is_empty() {
+            let kinds = restriction.advertised_kinds(self.code_action_kinds());
+            if kinds.is_empty() {
+                // It lists only kinds that aren't kept: nothing to ask it for.
+                if let Some(o) = self.raw.as_object_mut() {
+                    o.remove("codeActionProvider");
+                }
+            } else {
+                if !self.raw["codeActionProvider"].is_object() {
+                    self.raw["codeActionProvider"] = json!({});
+                }
+                self.raw["codeActionProvider"]["codeActionKinds"] = json!(kinds);
+            }
+        }
+        if !restriction.allows("semanticTokensProvider") {
+            self.semantic_legend = None;
+        }
+        self.restriction = restriction;
     }
 
     /// Whether the server statically advertises the capability under `key`.
@@ -325,11 +452,18 @@ impl ServerCaps {
             self.raw["workspace"]["textDocumentContent"] = opts.clone();
             return;
         }
+        if let Some(key) = capability_key(method)
+            && !self.restriction.allows(key)
+        {
+            return;
+        }
         if method == "textDocument/semanticTokens"
             && let Some(opts) = options
         {
             self.raw["semanticTokensProvider"] = opts.clone();
+            let restriction = std::mem::take(&mut self.restriction);
             *self = Self::parse(std::mem::take(&mut self.raw));
+            self.restriction = restriction;
             return;
         }
         if method == "textDocument/didSave" {
@@ -349,6 +483,11 @@ impl ServerCaps {
             && !self.has(key)
         {
             self.raw[key] = options.cloned().filter(|o| o.is_object()).unwrap_or(Value::Bool(true));
+            if key == "codeActionProvider" {
+                // Registered kinds go through the same narrowing as announced ones.
+                let restriction = std::mem::take(&mut self.restriction);
+                self.restrict(restriction);
+            }
         }
     }
 
@@ -426,4 +565,122 @@ mod tests {
         c.unregister("workspace/willRenameFiles");
         assert!(c.file_operation("willRename").is_none());
     }
+
+    fn restriction(features: &[&str], kinds: &[&str]) -> Restriction {
+        let owned = |v: &[&str]| v.iter().map(|s| s.to_string()).collect::<Vec<_>>();
+        Restriction::new("test", &owned(features), &owned(kinds))
+    }
+
+    #[test]
+    fn features_drop_other_capabilities() {
+        let mut c = ServerCaps::parse(json!({
+            "textDocumentSync": 2,
+            "completionProvider": {},
+            "hoverProvider": true,
+            "documentFormattingProvider": true,
+            "foldingRangeProvider": true,
+            "codeActionProvider": { "resolveProvider": true },
+            "executeCommandProvider": { "commands": ["rope.extract"] },
+            "semanticTokensProvider": { "legend": { "tokenTypes": [], "tokenModifiers": [] }, "full": true },
+            "workspace": { "fileOperations": { "willRename": { "filters": [] } } },
+            "experimental": { "x": true }
+        }));
+        c.restrict(restriction(&["code-action", "nope"], &[]));
+        assert!(c.has("codeActionProvider") && c.has_sub("codeActionProvider", "resolveProvider"));
+        assert_eq!(c.commands(), ["rope.extract"]);
+        for key in ["completionProvider", "hoverProvider", "documentFormattingProvider", "foldingRangeProvider"] {
+            assert!(!c.has(key), "{key}");
+        }
+        assert!(c.semantic_legend.is_none() && !c.semantic_tokens_full());
+        assert_eq!((c.sync, c.open_close), (SyncKind::Incremental, true));
+        assert!(c.file_operation("willRename").is_some() && c.raw["experimental"]["x"] == true);
+        assert!(!c.restriction.diagnostics());
+        assert_eq!(c.code_action_kinds(), None, "no kind filter: the server may return any kind");
+
+        // Later registrations go through the same filter.
+        c.register("textDocument/hover", None);
+        c.register("textDocument/semanticTokens", Some(&json!({ "legend": {}, "full": true })));
+        assert!(!c.has("hoverProvider") && !c.has("semanticTokensProvider"));
+        c.register("textDocument/didSave", None);
+        assert_eq!(c.save, Some(false));
+
+        let mut c = ServerCaps::parse(json!({ "hoverProvider": true, "semanticTokensProvider": { "full": true } }));
+        c.restrict(Restriction::default());
+        assert!(c.has("hoverProvider") && c.restriction.diagnostics(), "no `features`: everything");
+        c.restrict(restriction(&["semantic-tokens", "diagnostics"], &[]));
+        c.register("textDocument/semanticTokens", Some(&json!({ "legend": {}, "full": true })));
+        assert!(!c.has("hoverProvider") && c.semantic_tokens_full() && c.restriction.diagnostics());
+        c.register("textDocument/hover", None);
+        assert!(!c.has("hoverProvider"), "the restriction survives re-parsing semantic tokens");
+    }
+
+    #[test]
+    fn code_action_kinds_narrow_what_is_asked_and_kept() {
+        let r = restriction(&[], &["refactor", "source.fixAll"]);
+        assert!(r.keeps_action(Some("refactor")) && r.keeps_action(Some("refactor.extract.function")));
+        assert!(r.keeps_action(Some("source.fixAll.ruff")));
+        assert!(!r.keeps_action(Some("refactorx")) && !r.keeps_action(Some("source")) && !r.keeps_action(None));
+        assert!(Restriction::default().keeps_action(None));
+
+        let kinds = |provider: Value| {
+            let mut c = ServerCaps::parse(json!({ "codeActionProvider": provider }));
+            c.restrict(r.clone());
+            c.has("codeActionProvider").then(|| c.code_action_kinds().unwrap())
+        };
+        assert_eq!(kinds(json!(true)), Some(vec!["refactor".into(), "source.fixAll".into()]));
+        assert_eq!(
+            kinds(json!({ "codeActionKinds": ["quickfix", "refactor.extract", "source"] })),
+            Some(vec!["refactor.extract".into(), "source.fixAll".into()]),
+        );
+        assert_eq!(kinds(json!({ "codeActionKinds": ["quickfix"] })), None, "nothing it lists is kept");
+
+        let mut c = ServerCaps::parse(json!({}));
+        c.restrict(r.clone());
+        c.register("textDocument/codeAction", Some(&json!({ "codeActionKinds": ["quickfix", "refactor.inline"] })));
+        assert_eq!(c.code_action_kinds(), Some(vec!["refactor.inline".into()]));
+    }
+
+    #[test]
+    fn language_definitions_use_known_feature_names() {
+        for lang in ide_language::LanguageRegistry::load(None).unwrap().all() {
+            for server in &lang.language_servers {
+                for name in &server.features {
+                    assert!(FEATURES.iter().any(|(n, _)| n == name), "{}: unknown feature `{name}`", server.name);
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn feature_names_cover_every_capability_the_ide_asks_for() {
+        let named: Vec<&str> = FEATURES.iter().flat_map(|(_, keys)| keys.iter().copied()).collect();
+        for method in [
+            "textDocument/completion",
+            "textDocument/hover",
+            "textDocument/signatureHelp",
+            "textDocument/definition",
+            "textDocument/declaration",
+            "textDocument/typeDefinition",
+            "textDocument/implementation",
+            "textDocument/references",
+            "textDocument/documentHighlight",
+            "textDocument/documentSymbol",
+            "workspace/symbol",
+            "textDocument/codeAction",
+            "workspace/executeCommand",
+            "textDocument/rename",
+            "textDocument/formatting",
+            "textDocument/rangeFormatting",
+            "textDocument/inlayHint",
+            "textDocument/inlineCompletion",
+            "textDocument/semanticTokens",
+            "textDocument/codeLens",
+            "textDocument/documentLink",
+            "textDocument/prepareCallHierarchy",
+            "textDocument/prepareTypeHierarchy",
+        ] {
+            let key = capability_key(method).unwrap();
+            assert!(named.contains(&key), "{method} ({key}) has no feature name");
+        }
+    }
 }

crates/ide-lsp/src/handler.rs

@@ -111,6 +111,10 @@ impl ClientHandler {
     }
 
     fn publish_diagnostics(&self, mgr: &LspManager, params: Value) {
+        // Problems come only from servers used for `diagnostics`.
+        if self.server.running_gen(self.generation).is_some_and(|run| !run.caps.read().restriction.diagnostics()) {
+            return;
+        }
         let params: lsp::PublishDiagnosticsParams = match serde_json::from_value(params) {
             Ok(p) => p,
             Err(e) => {

crates/ide-lsp/src/inspect.rs

@@ -156,6 +156,7 @@ impl LspManager {
             .iter()
             .zip(ready)
             .filter_map(|(s, run)| Some(Target { server: s.clone(), run: run? }))
+            .filter(|t| t.caps().restriction.diagnostics())
             .collect();
         if targets.is_empty() {
             return Ok(None);

crates/ide-lsp/src/launch.rs

@@ -96,8 +96,12 @@ impl Launcher for ProcessLauncher {
         cancel: &CancellationToken,
     ) -> Result<(Peer, Option<PathBuf>), LaunchError> {
         let search = server_search_path(config);
-        let binary = ide_core::tool_path::find_command(&config.command, &search, root)
-            .and_then(|b| resolve_rustup_proxy(&config.command, b));
+        let binary = match &config.pinned {
+            // A plugin's server: the approved program, unchanged since.
+            Some(pin) => Some(pin.verify().map_err(LaunchError::Failed)?.to_path_buf()),
+            None => ide_core::tool_path::find_command(&config.command, &search, root)
+                .and_then(|b| resolve_rustup_proxy(&config.command, b)),
+        };
         let mut env: Vec<(String, String)> = vec![("PATH".into(), search.to_string_lossy().into_owned())];
         env.extend(config.env.iter().filter(|(k, _)| *k != "PATH").map(|(k, v)| (k.clone(), v.clone())));
         if let Some(addr) = &config.connect {
@@ -120,6 +124,9 @@ impl Launcher for ProcessLauncher {
     }
 
     fn available(&self, config: &LanguageServerConfig, root: &Path) -> bool {
+        if let Some(pin) = &config.pinned {
+            return pin.path.is_file();
+        }
         ide_core::tool_path::find_command(&config.command, &server_search_path(config), root).is_some()
     }
 }

crates/ide-lsp/src/lib.rs

@@ -570,7 +570,10 @@ impl LspManager {
                 if let Some(info) = result.get("serverInfo") {
                     tracing::info!("{} initialized: {info}", server.name);
                 }
-                ServerCaps::parse(result.get("capabilities").cloned().unwrap_or_else(|| json!({})))
+                let mut caps = ServerCaps::parse(result.get("capabilities").cloned().unwrap_or_else(|| json!({})));
+                let cfg = server.effective_config();
+                caps.restrict(caps::Restriction::new(&server.name, &cfg.features, &cfg.code_action_kinds));
+                caps
             }
             Err(e) => {
                 tracing::warn!("{}: initialize failed: {e}", server.name);
@@ -1593,8 +1596,14 @@ impl LspManager {
                 Ok(actions) => {
                     let conv = self.conv(t.enc());
                     let acc = out.value.get_or_insert_with(Vec::new);
+                    let caps = t.caps();
                     acc.extend(
-                        actions.unwrap_or_default().into_iter().map(|a| convert::code_action(&conv, a, t.server.id)),
+                        actions
+                            .unwrap_or_default()
+                            .into_iter()
+                            .map(|a| convert::code_action(&conv, a, t.server.id))
+                            // Servers may ignore `only`, and the kinds kept for this one.
+                            .filter(|a| caps.restriction.keeps_action(a.kind.as_deref())),
                     );
                 }
                 Err(e) => out.fail(e),
@@ -1964,6 +1973,29 @@ impl LspManager {
         }
     }
 
+    /// Files that changed on disk, outside the editor too (a checkout, another tool): each running
+    /// server hears of those of its languages under its root through `workspace/didChangeWatchedFiles`.
+    /// Without it jdtls's incremental build never sees them, so a launch runs stale classes.
+    pub fn watched_files_changed(&self, created: &[PathBuf], modified: &[PathBuf], removed: &[PathBuf]) {
+        let servers: Vec<Arc<Server>> = self.servers.lock().clone();
+        for s in servers {
+            let Some(run) = s.running() else { continue };
+            let languages = s.languages();
+            let changes: Vec<Value> = [(created, 1), (modified, 2), (removed, 3)]
+                .into_iter()
+                .flat_map(|(paths, kind)| paths.iter().map(move |p| (p, kind)))
+                .filter(|(p, _)| p.starts_with(&s.root) && languages.contains(&self.languages.detect(p, None)))
+                .map(|(p, kind)| json!({ "uri": uri::path_to_uri(p), "type": kind }))
+                .collect();
+            if changes.is_empty() {
+                continue;
+            }
+            if let Err(e) = run.peer.notify("workspace/didChangeWatchedFiles", json!({ "changes": changes })) {
+                tracing::debug!("{}: didChangeWatchedFiles: {e}", s.name);
+            }
+        }
+    }
+
     /// Checks initialized capabilities, including dynamic registrations, before choosing a formatter.
     pub async fn can_format(&self, doc: DocId) -> IdeResult<bool> {
         let snap = self.snapshot(doc)?;

crates/ide-lsp/tests/mock_server.rs

@@ -225,9 +225,12 @@ fn server_cfg(name: &str) -> LanguageServerConfig {
         install_hint: Some(format!("install {name}")),
         connect: None,
         fallback: false,
+        features: Vec::new(),
+        code_action_kinds: Vec::new(),
         max_java: None,
         launch_error: None,
         tsserver_project: false,
+        pinned: None,
     }
 }
 
@@ -402,6 +405,37 @@ async fn linked_projects_initialize_separate_language_server_roots() {
     h.mgr.shutdown_all().await;
 }
 
+#[tokio::test(flavor = "multi_thread")]
+async fn files_changed_on_disk_reach_the_servers_of_their_language() {
+    let h = harness(&[("mock", incremental_caps())]);
+    h.open("a.mk", "x");
+    h.wait_status("mock", ServerStatus::Ready).await;
+    let s = h.launcher.state("mock");
+    let (created, modified, removed) = (h.root.join("new.mk"), h.root.join("a.mk"), h.root.join("old.mk"));
+    // Other languages and files outside the server's root are left out.
+    let other = h.root.join("notes.txt");
+    let outside = tempfile::tempdir().unwrap().path().join("far.mk");
+    h.mgr.watched_files_changed(
+        &[created.clone(), other],
+        &[modified.clone(), outside],
+        std::slice::from_ref(&removed),
+    );
+    eventually(|| !s.notified("workspace/didChangeWatchedFiles").is_empty()).await;
+    assert_eq!(
+        s.notified("workspace/didChangeWatchedFiles")[0]["changes"],
+        json!([
+            { "uri": uri_of(&created), "type": 1 },
+            { "uri": uri_of(&modified), "type": 2 },
+            { "uri": uri_of(&removed), "type": 3 },
+        ])
+    );
+    // Nothing of its languages: no notification.
+    h.mgr.watched_files_changed(&[h.root.join("b.txt")], &[], &[]);
+    tokio::time::sleep(std::time::Duration::from_millis(100)).await;
+    assert_eq!(s.notified("workspace/didChangeWatchedFiles").len(), 1);
+    h.mgr.shutdown_all().await;
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn initialize_and_incremental_sync() {
     let h = harness(&[("mock", incremental_caps())]);
@@ -1748,6 +1782,64 @@ async fn code_action_query_without_listed_kinds() {
     assert_eq!(q.advertised_kinds, None, "`codeActionProvider` without `codeActionKinds` may return any kind");
 }
 
+#[tokio::test(flavor = "multi_thread")]
+async fn features_limit_what_a_server_is_used_for() {
+    // A refactoring-only server listed first, announcing everything the main one does.
+    let h = harness_configured("mock", "mk", &[("rope", incremental_caps()), ("main", incremental_caps())], |cfg| {
+        if cfg.name == "rope" {
+            cfg.features = vec!["code-action".into()];
+            cfg.code_action_kinds = vec!["refactor".into()];
+        }
+    });
+    let (doc, path) = h.open("a.mk", "let x = 1;\n");
+    for name in ["rope", "main"] {
+        h.wait_status(name, ServerStatus::Ready).await;
+    }
+    let (rope, main) = (h.launcher.state("rope"), h.launcher.state("main"));
+    for s in [&rope, &main] {
+        s.respond("textDocument/hover", json!({ "contents": "x" }));
+        s.respond("textDocument/formatting", json!([]));
+    }
+
+    h.mgr.hover(doc, Pos::new(0, 4), Default::default()).await.unwrap();
+    assert_eq!(main.requested("textDocument/hover").len(), 1);
+    h.mgr
+        .format(doc, None, FormatOptions { tab_size: 2, insert_spaces: true, on_save: false, tool: None })
+        .await
+        .unwrap();
+    assert_eq!(main.requested("textDocument/formatting").len(), 1);
+    assert!(rope.requested("textDocument/hover").is_empty() && rope.requested("textDocument/formatting").is_empty());
+
+    rope.respond(
+        "textDocument/codeAction",
+        json!([
+            { "title": "Organize imports", "kind": "source.organizeImports" },
+            { "title": "Extract variable", "kind": "refactor.extract.variable" },
+            { "title": "Run", "command": "mock.run" }
+        ]),
+    );
+    main.respond("textDocument/codeAction", json!([{ "title": "Fix", "kind": "quickfix" }]));
+    let q = h.mgr.code_action_query(doc, rng(0, 8, 0, 9), vec![], ide_core::CancellationToken::new()).await.unwrap();
+    let mut titles: Vec<&str> = q.actions.iter().map(|a| a.title.as_str()).collect();
+    titles.sort();
+    assert_eq!(titles, ["Extract variable", "Fix"], "rope's other kinds and bare commands are dropped");
+
+    let diag =
+        json!([{ "range": {"start":{"line":0,"character":4},"end":{"line":0,"character":5}}, "message": "unused" }]);
+    rope.peer()
+        .notify("textDocument/publishDiagnostics", json!({ "uri": uri_of(&path), "diagnostics": diag }))
+        .unwrap();
+    main.peer()
+        .notify("textDocument/publishDiagnostics", json!({ "uri": uri_of(&path), "diagnostics": diag }))
+        .unwrap();
+    eventually(|| {
+        h.events.lock().iter().any(|e| matches!(e, IdeEvent::Diagnostics { source, .. } if source == "main"))
+    })
+    .await;
+    tokio::time::sleep(Duration::from_millis(100)).await;
+    assert!(!h.events.lock().iter().any(|e| matches!(e, IdeEvent::Diagnostics { source, .. } if source == "rope")));
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn shutdown_all_stops_gracefully() {
     let h = harness(&[("mock", incremental_caps())]);

crates/ide-lsp/tests/real_servers.rs

@@ -129,9 +129,12 @@ async fn missing_binary_is_reported_with_install_hint() {
         install_hint: Some("npm i -g nope-ls".into()),
         connect: None,
         fallback: false,
+        features: Vec::new(),
+        code_action_kinds: Vec::new(),
         max_java: None,
         launch_error: None,
         tsserver_project: false,
+        pinned: None,
     };
     let (mgr, events) = manager(dir.path(), LanguageRegistry::from_configs(vec![lang("nope", "nope", server)]));
     let path = dir.path().join("a.nope");
@@ -395,9 +398,12 @@ async fn typescript_language_server_end_to_end() {
         install_hint: None,
         connect: None,
         fallback: false,
+        features: Vec::new(),
+        code_action_kinds: Vec::new(),
         max_java: None,
         launch_error: None,
         tsserver_project: false,
+        pinned: None,
     };
     let (mgr, events) = manager(&root, LanguageRegistry::from_configs(vec![lang("typescript", "ts", server)]));
     let doc = DocId::next();
@@ -441,9 +447,12 @@ fn npm_server(tools: &Path, name: &str, bin: &str, init: Option<serde_json::Valu
         install_hint: None,
         connect: None,
         fallback: false,
+        features: Vec::new(),
+        code_action_kinds: Vec::new(),
         max_java: None,
         launch_error: None,
         tsserver_project: false,
+        pinned: None,
     }
 }
 

crates/ide-plugin/Cargo.toml

@@ -1,21 +1,24 @@
 [package]
 name = "ide-plugin"
-description = "Sandboxed WebAssembly plugin host (wasmtime component model + WASI preview 2)"
+description = "WebAssembly runtime for plugins (wasmtime component model + WASI preview 2)"
 version.workspace = true
 edition.workspace = true
 license.workspace = true
 
 [dependencies]
 ide-core.workspace = true
-ide-language.workspace = true
+ide-extension.workspace = true
+blake3.workspace = true
 serde.workspace = true
 serde_json.workspace = true
 specta.workspace = true
-toml.workspace = true
 thiserror.workspace = true
 tracing.workspace = true
 parking_lot.workspace = true
-tempfile.workspace = true
-zip.workspace = true
-wasmtime = { version = "49.0.4", default-features = false, features = ["runtime", "cranelift", "component-model", "std", "parallel-compilation"] }
+semver = "1"
+wasmtime = { version = "49.0.4", default-features = false, features = ["runtime", "cranelift", "component-model", "std", "parallel-compilation", "async"] }
 wasmtime-wasi = { version = "49.0.4", default-features = false, features = ["p2"] }
+
+[dev-dependencies]
+tempfile.workspace = true
+tokio = { workspace = true, features = ["rt-multi-thread", "macros", "time"] }

crates/ide-plugin/src/actor.rs

@@ -0,0 +1,312 @@
+//! One thread per active plugin owning its [`Runtime`].
+//!
+//! Callers queue jobs and wait on a reply channel instead of holding a lock
+//! across the call, so an edit-path caller can stop waiting at its soft
+//! deadline while the call runs on (and is interrupted at the hard deadline
+//! by the store's epoch callback), and the call can be cancelled from any
+//! thread. A trap poisons the instance: the actor drops it and ends; the
+//! host's supervisor decides when to start a new one.
+//!
+//! wasmtime's async API would let one thread drive every instance, but needs
+//! async host bindings throughout; with a plugin's instance only ever entered
+//! by one job at a time a parked thread per active plugin costs little, and
+//! idle reclaim ends it.
+
+use crate::runtime::{CallCancel, CallError, Runtime};
+use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
+use std::sync::{Arc, Mutex, mpsc};
+use std::thread::JoinHandle;
+use std::time::{Duration, Instant};
+
+type Job = Box<dyn FnOnce(&mut Option<Runtime>) + Send>;
+
+/// Why an [`Actor::call`] produced no result.
+#[derive(Debug)]
+pub enum ActorError {
+    /// The plugin's own outcome: an error it returned, or a trap (the actor has ended).
+    Call(CallError),
+    /// The caller's wait ran out; the result, if any, is dropped.
+    SoftTimeout,
+    /// The actor ended (an earlier call trapped, or it was stopped) before running the call.
+    Stopped,
+    /// The caller cancelled the call (`call_cancellable`).
+    Cancelled,
+}
+
+/// A call queued with [`Actor::submit`].
+pub struct Pending<R> {
+    /// The outcome and when the plugin's thread produced it.
+    result: mpsc::Receiver<(Result<R, CallError>, Instant)>,
+    give_up: Option<Instant>,
+    alive: Arc<AtomicBool>,
+}
+
+impl<R> Pending<R> {
+    /// Waits for the outcome, until the call's soft deadline if it has one. A
+    /// result produced after that deadline is dropped even when it is already
+    /// there (the caller was not scheduled in time, or waited on another call
+    /// first), so the deadline holds however busy the machine is; a failure is
+    /// still reported.
+    pub fn wait(self) -> Result<R, ActorError> {
+        let outcome = match self.give_up {
+            Some(t) => match self.result.recv_timeout(t.saturating_duration_since(Instant::now())) {
+                Ok((Ok(_), done)) if done > t => return Err(ActorError::SoftTimeout),
+                Ok((r, _)) => r,
+                Err(mpsc::RecvTimeoutError::Timeout) => return Err(ActorError::SoftTimeout),
+                Err(mpsc::RecvTimeoutError::Disconnected) => {
+                    // Skipped as too late, or the actor ended.
+                    let alive = self.alive.load(Ordering::Acquire);
+                    return Err(if alive { ActorError::SoftTimeout } else { ActorError::Stopped });
+                }
+            },
+            None => self.result.recv().map_err(|_| ActorError::Stopped)?.0,
+        };
+        outcome.map_err(ActorError::Call)
+    }
+}
+
+pub struct Actor {
+    tx: Mutex<Option<mpsc::Sender<Job>>>,
+    thread: Mutex<Option<JoinHandle<()>>>,
+    cancel: Arc<CallCancel>,
+    alive: Arc<AtomicBool>,
+    /// The trap that ended the actor, until someone takes it to report it.
+    crash: Arc<Mutex<Option<String>>>,
+    busy: Arc<AtomicBool>,
+    /// Milliseconds since `epoch` at the last call's end.
+    last_used: Arc<AtomicU64>,
+    epoch: Instant,
+}
+
+impl Actor {
+    /// Moves an activated runtime onto its own thread.
+    pub fn spawn(name: &str, runtime: Runtime) -> std::io::Result<Self> {
+        let (tx, rx) = mpsc::channel::<Job>();
+        let cancel = runtime.cancel_handle();
+        let alive = Arc::new(AtomicBool::new(true));
+        let busy = Arc::new(AtomicBool::new(false));
+        let last_used = Arc::new(AtomicU64::new(0));
+        let epoch = Instant::now();
+        let thread = {
+            let (alive, busy, last_used) = (alive.clone(), busy.clone(), last_used.clone());
+            std::thread::Builder::new().name(format!("plugin:{name}")).spawn(move || {
+                let mut slot = Some(runtime);
+                while let Ok(job) = rx.recv() {
+                    busy.store(true, Ordering::Release);
+                    job(&mut slot);
+                    last_used.store(epoch.elapsed().as_millis() as u64, Ordering::Release);
+                    busy.store(false, Ordering::Release);
+                    if slot.is_none() {
+                        break;
+                    }
+                }
+                alive.store(false, Ordering::Release);
+                // Queued jobs are dropped with `rx`: their callers see `Stopped`.
+                drop(rx);
+                if let Some(mut rt) = slot {
+                    rt.deactivate();
+                }
+            })?
+        };
+        Ok(Self {
+            tx: Mutex::new(Some(tx)),
+            thread: Mutex::new(Some(thread)),
+            cancel,
+            alive,
+            crash: Arc::default(),
+            busy,
+            last_used,
+            epoch,
+        })
+    }
+
+    /// Runs `f` on the plugin's thread. With `wait`, gives up after that long
+    /// (counting the time queued behind other calls) and the call, if it has
+    /// not started yet, is skipped. Without, waits for the outcome: the
+    /// runtime's own deadline bounds it.
+    pub fn call<R: Send + 'static>(
+        &self,
+        wait: Option<Duration>,
+        f: impl FnOnce(&mut Runtime) -> Result<R, CallError> + Send + 'static,
+    ) -> Result<R, ActorError> {
+        self.submit(wait, f)?.wait()
+    }
+
+    /// Queues `f` like [`call`](Self::call) and returns at once, so a caller
+    /// can start calls on several plugins and then wait for all of them: the
+    /// wait is the slowest one's, not the sum.
+    pub fn submit<R: Send + 'static>(
+        &self,
+        wait: Option<Duration>,
+        f: impl FnOnce(&mut Runtime) -> Result<R, CallError> + Send + 'static,
+    ) -> Result<Pending<R>, ActorError> {
+        let give_up = wait.map(|w| Instant::now() + w);
+        let (reply, result) = mpsc::sync_channel(1);
+        let (crash, alive) = (self.crash.clone(), self.alive.clone());
+        let job: Job = Box::new(move |slot| {
+            if give_up.is_some_and(|t| Instant::now() >= t) {
+                return;
+            }
+            let Some(rt) = slot.as_mut() else { return };
+            let outcome = f(rt);
+            if let Err(CallError::Trap(e)) = &outcome {
+                *crash.lock().unwrap_or_else(|e| e.into_inner()) = Some(e.clone());
+                // Before the reply: the caller sees the actor dead.
+                alive.store(false, Ordering::Release);
+                *slot = None;
+            }
+            let _ = reply.send((outcome, Instant::now()));
+        });
+        {
+            let tx = self.tx.lock().unwrap_or_else(|e| e.into_inner());
+            let Some(tx) = tx.as_ref() else { return Err(ActorError::Stopped) };
+            tx.send(job).map_err(|_| ActorError::Stopped)?;
+        }
+        Ok(Pending { result, give_up, alive: self.alive.clone() })
+    }
+
+    /// Like [`call`](Self::call) without a soft deadline, but `cancel` (the
+    /// caller's request was superseded) cancels the call cooperatively, and
+    /// interrupts it if it has not returned `grace` later. Returns
+    /// [`ActorError::Cancelled`] then.
+    pub fn call_cancellable<R: Send + 'static>(
+        &self,
+        cancel: &ide_core::CancellationToken,
+        grace: Duration,
+        f: impl FnOnce(&mut Runtime) -> Result<R, CallError> + Send + 'static,
+    ) -> Result<R, ActorError> {
+        let (reply, result) = mpsc::sync_channel(1);
+        let (crash, alive) = (self.crash.clone(), self.alive.clone());
+        let skip = cancel.clone();
+        let job: Job = Box::new(move |slot| {
+            if skip.is_cancelled() {
+                return;
+            }
+            let Some(rt) = slot.as_mut() else { return };
+            let outcome = f(rt);
+            if let Err(CallError::Trap(e)) = &outcome {
+                *crash.lock().unwrap_or_else(|e| e.into_inner()) = Some(e.clone());
+                alive.store(false, Ordering::Release);
+                *slot = None;
+            }
+            let _ = reply.send(outcome);
+        });
+        {
+            let tx = self.tx.lock().unwrap_or_else(|e| e.into_inner());
+            let Some(tx) = tx.as_ref() else { return Err(ActorError::Stopped) };
+            tx.send(job).map_err(|_| ActorError::Stopped)?;
+        }
+        let mut cancelled_at: Option<Instant> = None;
+        loop {
+            match result.recv_timeout(Duration::from_millis(5)) {
+                Ok(outcome) if cancelled_at.is_some() => {
+                    drop(outcome);
+                    return Err(ActorError::Cancelled);
+                }
+                Ok(outcome) => return outcome.map_err(ActorError::Call),
+                Err(mpsc::RecvTimeoutError::Disconnected) => {
+                    return Err(if cancel.is_cancelled() { ActorError::Cancelled } else { ActorError::Stopped });
+                }
+                Err(mpsc::RecvTimeoutError::Timeout) => {}
+            }
+            if !cancel.is_cancelled() {
+                continue;
+            }
+            match cancelled_at {
+                None => {
+                    cancelled_at = Some(Instant::now());
+                    if self.is_busy() {
+                        self.cancel.cancel_soft();
+                    }
+                }
+                Some(at) if at.elapsed() >= grace => {
+                    // Did not return in time: interrupt it (the instance is rebuilt).
+                    self.cancel();
+                    return Err(ActorError::Cancelled);
+                }
+                Some(_) => {}
+            }
+        }
+    }
+
+    /// Queues `f` without waiting; `done` gets the outcome on the actor's
+    /// thread (`Stopped` if the actor ended before running it).
+    pub fn post<R: Send + 'static>(
+        &self,
+        f: impl FnOnce(&mut Runtime) -> Result<R, CallError> + Send + 'static,
+        done: impl FnOnce(Result<R, ActorError>) + Send + 'static,
+    ) {
+        let (crash, alive) = (self.crash.clone(), self.alive.clone());
+        let job: Job = Box::new(move |slot| {
+            let Some(rt) = slot.as_mut() else { return done(Err(ActorError::Stopped)) };
+            let outcome = f(rt);
+            if let Err(CallError::Trap(e)) = &outcome {
+                *crash.lock().unwrap_or_else(|e| e.into_inner()) = Some(e.clone());
+                alive.store(false, Ordering::Release);
+                *slot = None;
+            }
+            done(outcome.map_err(ActorError::Call));
+        });
+        let tx = self.tx.lock().unwrap_or_else(|e| e.into_inner());
+        // A job that can't be queued is dropped, and with it `done` (unrun):
+        // the caller sees the actor dead on its next look.
+        if let Some(tx) = tx.as_ref() {
+            let _ = tx.send(job);
+        }
+    }
+
+    /// Cooperatively cancels the running call (see [`call_cancellable`](Self::call_cancellable)).
+    pub fn cancel_soft(&self) {
+        if self.is_busy() {
+            self.cancel.cancel_soft();
+        }
+    }
+
+    /// Interrupts the running call (it fails as a trap: the instance is dropped).
+    pub fn cancel(&self) {
+        if self.busy.load(Ordering::Acquire) {
+            self.cancel.cancel();
+        }
+    }
+
+    /// The trap that ended this actor; `Some` only for the first caller, which
+    /// reports it (also when the caller that saw it had stopped waiting).
+    pub fn take_crash(&self) -> Option<String> {
+        self.crash.lock().unwrap_or_else(|e| e.into_inner()).take()
+    }
+
+    /// The runtime is still usable (no call trapped, not stopped).
+    pub fn is_alive(&self) -> bool {
+        self.alive.load(Ordering::Acquire)
+    }
+
+    pub fn is_busy(&self) -> bool {
+        self.busy.load(Ordering::Acquire)
+    }
+
+    /// Time since the last call ended (or since start).
+    pub fn idle_for(&self) -> Duration {
+        let last = Duration::from_millis(self.last_used.load(Ordering::Acquire));
+        self.epoch.elapsed().saturating_sub(last)
+    }
+
+    /// Deactivates the plugin and ends the thread after the queued calls.
+    /// With `join`, waits for that (bounded by the runtime's deadlines).
+    pub fn stop(&self, join: bool) {
+        self.tx.lock().unwrap_or_else(|e| e.into_inner()).take();
+        if join {
+            let thread = self.thread.lock().unwrap_or_else(|e| e.into_inner()).take();
+            if let Some(t) = thread
+                && t.thread().id() != std::thread::current().id()
+            {
+                let _ = t.join();
+            }
+        }
+    }
+}
+
+impl Drop for Actor {
+    fn drop(&mut self) {
+        self.stop(false);
+    }
+}

crates/ide-plugin/src/lib.rs

@@ -1,771 +1,24 @@
-//! Sandboxed WebAssembly plugin host (Zed-style).
+//! The WebAssembly runtime for plugins (wasmtime, component model, WASI
+//! preview 2). Package handling, extension points and grants live in
+//! `ide-extension`; the host that assembles them is `ide-host::plugins`.
 //!
-//! A plugin is a directory with a `plugin.toml` manifest ([`PluginManifest`])
-//! and, optionally, a WebAssembly component implementing the
-//! `openidea:plugin/[email protected]` world (`wit/plugin.wit`). Contribution-only
-//! plugins (themes, languages) need no code.
-//!
-//! Each plugin with code runs in its own wasmtime `Store` with WASI preview 2
-//! (no files, env, network), a fuel budget and wall-clock deadline per call,
-//! and a linear-memory cap. A trap (panic, budget exhausted, permission
-//! violation) drops the instance and marks the plugin `Failed` for the session;
-//! the IDE keeps running.
-//!
-//! Sources: `<plugins_dir>/<id>/` (installed) and `<project>/.openidea/plugins/*/`
-//! (dev plugins, loaded by [`PluginHost::sync_project`]).
+//! Each plugin with code runs in its own wasmtime `Store`: no files, env or
+//! network beyond what [`HostApi`] grants, a fuel budget and wall-clock
+//! deadline per call, and a linear-memory cap. A trap (panic, budget
+//! exhausted, permission violation, cancellation) poisons the instance; the
+//! host drops it. Each active plugin's runtime lives on its own [`Actor`] thread.
 
-mod manifest;
-mod package;
+mod actor;
 mod runtime;
 mod sandbox;
-mod theme;
 mod types;
+mod wit_host;
 
-pub use manifest::{
-    API_VERSION, CommandDecl, Contributions, FileDecl, MANIFEST_FILE, Permission, PluginManifest, ThemeDecl,
+pub use actor::{Actor, ActorError, Pending};
+pub use runtime::{
+    API_VERSION, CANCELLED, CallCancel, CallError, GuestError, HostApi, PluginEngine, Runtime, RuntimeSetup, check_api,
+    component_api, host_api,
 };
-pub use sandbox::resolve_in_root;
-pub use theme::{ThemeDef, ThemeKind};
+pub use sandbox::{MAX_READ_BYTES, read_text, resolve_in_root};
 pub use types::*;
-
-use ide_core::{IdeError, IdeResult};
-use ide_language::LanguageConfig;
-use parking_lot::{Condvar, Mutex, RwLock};
-use runtime::{CallEffects, CallError, PluginEngine, Registrations, Runtime, RuntimeSetup};
-use serde::{Deserialize, Serialize};
-use std::collections::{BTreeMap, BTreeSet, HashMap};
-use std::path::{Path, PathBuf};
-use std::sync::Arc;
-use std::time::Duration;
-
-const STATE_FILE: &str = "state.json";
-/// Top-level files copied with a package on install besides those the manifest references.
-const LICENSE_FILES: &[&str] =
-    &["LICENSE", "LICENSE.md", "LICENSE.txt", "NOTICE", "NOTICE.md", "NOTICE.txt", "COPYING"];
-/// Dev plugins live here, relative to a project root.
-pub const DEV_PLUGINS_DIR: &str = ".openidea/plugins";
-
-#[derive(Default, Serialize, Deserialize)]
-struct PersistedState {
-    #[serde(default)]
-    disabled: BTreeSet<String>,
-    #[serde(default)]
-    theme: Option<ThemeRef>,
-}
-
-#[derive(Clone, PartialEq, Serialize, Deserialize)]
-struct ThemeRef {
-    plugin: String,
-    theme: String,
-    /// The theme's window frame colour as the UI resolved it (`#rrggbb[aa]`), so
-    /// new windows open in it before the plugin is loaded.
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    frame: Option<String>,
-}
-
-struct Meta {
-    status: PluginStatus,
-    error: Option<String>,
-}
-
-struct LoadedPlugin {
-    manifest: PluginManifest,
-    dir: PathBuf,
-    source: PluginSource,
-    /// Project that owns a dev plugin.
-    dev_root: Option<PathBuf>,
-    /// Manifest contributions, restored on every (re)start.
-    static_regs: Registrations,
-    registrations: Arc<Mutex<Registrations>>,
-    meta: Mutex<Meta>,
-    runtime: Mutex<Option<Runtime>>,
-}
-
-impl LoadedPlugin {
-    fn is_live(&self) -> bool {
-        matches!(self.meta.lock().status, PluginStatus::Active | PluginStatus::Static)
-    }
-
-    fn set_failed(&self, error: String) {
-        let mut meta = self.meta.lock();
-        meta.status = PluginStatus::Failed;
-        meta.error = Some(error);
-    }
-}
-
-type ProjectPolicy = Arc<dyn Fn(&Path) -> bool + Send + Sync>;
-
-pub struct PluginHost {
-    project_policy: RwLock<ProjectPolicy>,
-    engine: PluginEngine,
-    plugins_dir: PathBuf,
-    sink: Arc<dyn PluginEventSink>,
-    limits: Limits,
-    plugins: RwLock<BTreeMap<String, Arc<LoadedPlugin>>>,
-    state: Mutex<PersistedState>,
-    /// client (window) → path of its focused editor.
-    active_files: Arc<Mutex<HashMap<String, String>>>,
-    /// Serializes loading / unloading so concurrent windows can't race.
-    lifecycle: Mutex<()>,
-    /// Set once the first [`load_all`](Self::load_all) has finished.
-    initial_load: (Mutex<bool>, Condvar),
-}
-
-impl PluginHost {
-    /// Creates the host; call [`load_all`](Self::load_all) to load installed plugins.
-    pub fn new(plugins_dir: PathBuf, sink: Arc<dyn PluginEventSink>, limits: Limits) -> IdeResult<Self> {
-        std::fs::create_dir_all(&plugins_dir)?;
-        let state = std::fs::read_to_string(plugins_dir.join(STATE_FILE))
-            .ok()
-            .and_then(|s| serde_json::from_str(&s).ok())
-            .unwrap_or_default();
-        Ok(Self {
-            project_policy: RwLock::new(Arc::new(|_| false)),
-            engine: PluginEngine::new().map_err(IdeError::internal)?,
-            plugins_dir,
-            sink,
-            limits,
-            plugins: RwLock::default(),
-            state: Mutex::new(state),
-            active_files: Arc::default(),
-            lifecycle: Mutex::new(()),
-            initial_load: (Mutex::new(false), Condvar::new()),
-        })
-    }
-
-    pub fn plugins_dir(&self) -> &Path {
-        &self.plugins_dir
-    }
-
-    /// Loads every package under the plugins directory (already loaded ones are kept).
-    pub fn load_all(&self) {
-        let _guard = self.lifecycle.lock();
-        for dir in package_dirs(&self.plugins_dir) {
-            if !self.is_loaded_from(&dir) {
-                self.load_dir(&dir, PluginSource::Installed, None);
-            }
-        }
-        let (done, cv) = &self.initial_load;
-        *done.lock() = true;
-        cv.notify_all();
-        self.emit(None, PluginEvent::CommandsChanged);
-    }
-
-    /// Waits (at most `timeout`) for the first [`load_all`](Self::load_all), so a
-    /// listing made at startup already holds the installed plugins and the
-    /// selected theme. Returns whether loading has finished.
-    pub fn wait_initial_load(&self, timeout: Duration) -> bool {
-        let (done, cv) = &self.initial_load;
-        let mut done = done.lock();
-        if !*done {
-            cv.wait_while_for(&mut done, |d| !*d, timeout);
-        }
-        *done
-    }
-
-    /// Loads new dev plugins from `<root>/.openidea/plugins/` and unloads vanished ones.
-    pub fn set_project_policy(&self, policy: ProjectPolicy) {
-        *self.project_policy.write() = policy;
-    }
-
-    pub fn restrict_project(&self, root: &Path) {
-        let _guard = self.lifecycle.lock();
-        let ids: Vec<_> = self
-            .plugins
-            .read()
-            .iter()
-            .filter(|(_, p)| p.dev_root.as_deref() == Some(root))
-            .map(|(id, _)| id.clone())
-            .collect();
-        for id in ids {
-            self.unload(&id);
-        }
-        self.emit(None, PluginEvent::CommandsChanged);
-    }
-
-    pub fn sync_project(&self, root: &Path) {
-        if !(self.project_policy.read())(root) {
-            self.restrict_project(root);
-            return;
-        }
-        let _guard = self.lifecycle.lock();
-        let dirs = package_dirs(&ide_core::project_dir::path(root, "plugins"));
-        let stale: Vec<String> = self
-            .plugins
-            .read()
-            .iter()
-            .filter(|(_, p)| p.dev_root.as_deref() == Some(root) && !dirs.contains(&p.dir))
-            .map(|(id, _)| id.clone())
-            .collect();
-        let mut changed = !stale.is_empty();
-        for id in stale {
-            self.unload(&id);
-        }
-        for dir in dirs {
-            if !self.is_loaded_from(&dir) {
-                self.load_dir(&dir, PluginSource::Dev, Some(root.to_path_buf()));
-                changed = true;
-            }
-        }
-        if changed {
-            self.emit(None, PluginEvent::CommandsChanged);
-        }
-    }
-
-    /// Installed plugins plus the dev plugins of `project` (if any).
-    pub fn list(&self, project: Option<&Path>) -> PluginsSnapshot {
-        let mut plugins: Vec<PluginInfo> = self
-            .plugins
-            .read()
-            .values()
-            .filter(|p| p.dev_root.is_none() || p.dev_root.as_deref() == project)
-            .map(|p| self.info(p))
-            .collect();
-        plugins.sort_by_key(|p| p.name.to_lowercase());
-        PluginsSnapshot { plugins, active_theme: self.active_theme() }
-    }
-
-    pub fn info_of(&self, id: &str) -> IdeResult<PluginInfo> {
-        Ok(self.info(&*self.get(id)?))
-    }
-
-    pub fn set_enabled(&self, id: &str, enabled: bool) -> IdeResult<()> {
-        let _guard = self.lifecycle.lock();
-        let plugin = self.get(id)?;
-        {
-            let mut state = self.state.lock();
-            if enabled {
-                state.disabled.remove(id)
-            } else {
-                state.disabled.insert(id.to_owned())
-            };
-        }
-        self.save_state();
-        self.stop(&plugin);
-        if enabled {
-            self.start(&plugin);
-        } else {
-            plugin.meta.lock().status = PluginStatus::Disabled;
-        }
-        self.emit(None, PluginEvent::CommandsChanged);
-        self.emit_theme_if_owned(id);
-        Ok(())
-    }
-
-    /// Re-reads a plugin from disk (e.g. after rebuilding a dev plugin).
-    pub fn reload(&self, id: &str) -> IdeResult<PluginInfo> {
-        let _guard = self.lifecycle.lock();
-        let plugin = self.get(id)?;
-        let (dir, source, root) = (plugin.dir.clone(), plugin.source, plugin.dev_root.clone());
-        self.unload(id);
-        let new_id = self.load_dir(&dir, source, root);
-        self.emit(None, PluginEvent::CommandsChanged);
-        self.emit_theme_if_owned(&new_id);
-        self.info_of(&new_id)
-    }
-
-    /// Installs the package at `path`: a folder, its `plugin.toml`, or a `.zip` of the folder.
-    pub fn install_from_path(&self, path: &Path) -> IdeResult<PluginInfo> {
-        if package::is_zip(path) && path.is_file() {
-            // Outside the plugins directory: a crash must not leave a package that loads.
-            let unpacked = tempfile::Builder::new().prefix("openidea-plugin-").tempdir()?;
-            let root = package::unpack_zip(path, unpacked.path())?;
-            return self.install_from_dir(&root);
-        }
-        if path.file_name().is_some_and(|name| name == MANIFEST_FILE) && path.is_file() {
-            return self.install_from_dir(path.parent().unwrap_or(path));
-        }
-        self.install_from_dir(path)
-    }
-
-    /// Copies a plugin package (manifest + referenced files) into the plugins
-    /// directory, replacing an installed version with the same id.
-    pub fn install_from_dir(&self, src: &Path) -> IdeResult<PluginInfo> {
-        let _guard = self.lifecycle.lock();
-        let manifest = PluginManifest::load(src).map_err(IdeError::invalid)?;
-        for file in manifest.files() {
-            if !src.join(file).is_file() {
-                return Err(IdeError::invalid(format!(
-                    "{} is missing (referenced by plugin.toml); build the plugin first",
-                    file.display()
-                )));
-            }
-        }
-        if let Some(wasm) = &manifest.wasm {
-            self.engine.compile(&src.join(wasm)).map_err(IdeError::invalid)?;
-        }
-        let id = manifest.id.clone();
-        if let Some(existing) = self.plugins.read().get(&id)
-            && existing.source == PluginSource::Dev
-        {
-            return Err(IdeError::new(
-                ide_core::error::ErrorKind::AlreadyExists,
-                format!("a dev plugin with id {id:?} is loaded from {}", existing.dir.display()),
-            ));
-        }
-        let target = self.plugins_dir.join(&id);
-        let same_dir = src.canonicalize().ok().zip(target.canonicalize().ok()).is_some_and(|(a, b)| a == b);
-        self.unload(&id);
-        if !same_dir {
-            let staging = self.plugins_dir.join(format!(".install-{id}"));
-            let _ = std::fs::remove_dir_all(&staging);
-            let copy = || -> std::io::Result<()> {
-                std::fs::create_dir_all(&staging)?;
-                std::fs::copy(src.join(MANIFEST_FILE), staging.join(MANIFEST_FILE))?;
-                for file in manifest.files() {
-                    let to = staging.join(file);
-                    if let Some(parent) = to.parent() {
-                        std::fs::create_dir_all(parent)?;
-                    }
-                    std::fs::copy(src.join(file), to)?;
-                }
-                for name in LICENSE_FILES {
-                    if src.join(name).is_file() {
-                        std::fs::copy(src.join(name), staging.join(name))?;
-                    }
-                }
-                if target.exists() {
-                    std::fs::remove_dir_all(&target)?;
-                }
-                std::fs::rename(&staging, &target)
-            };
-            if let Err(e) = copy() {
-                let _ = std::fs::remove_dir_all(&staging);
-                return Err(e.into());
-            }
-        }
-        self.load_dir(&target, PluginSource::Installed, None);
-        self.emit(None, PluginEvent::CommandsChanged);
-        self.emit_theme_if_owned(&id);
-        self.info_of(&id)
-    }
-
-    pub fn uninstall(&self, id: &str) -> IdeResult<()> {
-        let _guard = self.lifecycle.lock();
-        let plugin = self.get(id)?;
-        if plugin.source != PluginSource::Installed {
-            return Err(IdeError::invalid("dev plugins are removed by deleting them from .openidea/plugins"));
-        }
-        self.unload(id);
-        std::fs::remove_dir_all(&plugin.dir)?;
-        let theme_cleared = {
-            let mut state = self.state.lock();
-            state.disabled.remove(id);
-            let owned = state.theme.as_ref().is_some_and(|t| t.plugin == id);
-            if owned {
-                state.theme = None;
-            }
-            owned
-        };
-        self.save_state();
-        self.emit(None, PluginEvent::CommandsChanged);
-        if theme_cleared {
-            self.emit(None, PluginEvent::ThemeChanged { theme: None });
-        }
-        Ok(())
-    }
-
-    /// Runs a plugin command. Blocks for up to the configured time limit.
-    pub fn run_command(
-        &self,
-        id: &str,
-        command: &str,
-        arg: Option<&str>,
-        invocation: Invocation,
-    ) -> IdeResult<Option<String>> {
-        let plugin = self.get(id)?;
-        let client = invocation.client.clone();
-        let mut runtime = plugin.runtime.lock();
-        let Some(rt) = runtime.as_mut() else {
-            let meta = plugin.meta.lock();
-            return Err(IdeError::unavailable(match meta.status {
-                PluginStatus::Disabled => format!("plugin {id:?} is disabled"),
-                PluginStatus::Static => format!("plugin {id:?} has no code to run commands"),
-                _ => format!("plugin {id:?} is not running: {}", meta.error.as_deref().unwrap_or("failed")),
-            }));
-        };
-        match rt.run_command(command, arg, invocation) {
-            Ok((value, fx)) => {
-                drop(runtime);
-                self.apply_effects(&plugin, fx);
-                Ok(value)
-            }
-            Err(CallError::Guest(e)) => Err(IdeError::internal(e)),
-            Err(CallError::Trap(e)) => {
-                *runtime = None;
-                drop(runtime);
-                self.fail(&plugin, &e, client.as_deref());
-                Err(IdeError::internal(format!("plugin {id:?} {e}")))
-            }
-        }
-    }
-
-    /// The UI reports which file its focused editor shows (for `active-file`).
-    pub fn set_active_file(&self, client: &str, path: Option<String>) {
-        let mut files = self.active_files.lock();
-        match path {
-            Some(p) => files.insert(client.to_owned(), p),
-            None => files.remove(client),
-        };
-    }
-
-    /// Selects a plugin theme (`None` restores the built-in theme).
-    pub fn set_theme(&self, selection: Option<(&str, &str)>) -> IdeResult<Option<ActiveTheme>> {
-        if let Some((plugin, theme)) = selection {
-            let p = self.get(plugin)?;
-            if !p.registrations.lock().themes.iter().any(|t| t.id == theme) {
-                return Err(IdeError::not_found(format!("plugin {plugin:?} has no theme {theme:?}")));
-            }
-        }
-        self.state.lock().theme =
-            selection.map(|(plugin, theme)| ThemeRef { plugin: plugin.into(), theme: theme.into(), frame: None });
-        self.save_state();
-        let active = self.active_theme();
-        self.emit(None, PluginEvent::ThemeChanged { theme: active.clone() });
-        Ok(active)
-    }
-
-    /// Records the selected theme's resolved window frame colour (`#rgb`,
-    /// `#rrggbb` or `#rrggbbaa`); ignored without a selected theme.
-    pub fn set_theme_frame(&self, frame: Option<&str>) -> IdeResult<()> {
-        if let Some(f) = frame
-            && !is_hex_color(f)
-        {
-            return Err(IdeError::invalid(format!("not a hex colour: {f:?}")));
-        }
-        let changed = match self.state.lock().theme.as_mut() {
-            Some(t) if t.frame.as_deref() != frame => {
-                t.frame = frame.map(str::to_owned);
-                true
-            }
-            _ => false,
-        };
-        if changed {
-            self.save_state();
-        }
-        Ok(())
-    }
-
-    /// Frame colour for a new window: the recorded one of the selected theme,
-    /// unless its plugin is disabled. Available before plugins are loaded.
-    pub fn startup_frame(&self) -> Option<String> {
-        let state = self.state.lock();
-        let t = state.theme.as_ref()?;
-        if state.disabled.contains(&t.plugin) {
-            return None;
-        }
-        t.frame.clone()
-    }
-
-    /// The selected plugin theme, when its plugin is enabled and running.
-    pub fn active_theme(&self) -> Option<ActiveTheme> {
-        let sel = self.state.lock().theme.clone()?;
-        let plugin = self.plugins.read().get(&sel.plugin).cloned()?;
-        if !plugin.is_live() {
-            return None;
-        }
-        let theme = plugin.registrations.lock().themes.iter().find(|t| t.id == sel.theme).cloned()?;
-        Some(ActiveTheme { plugin_id: sel.plugin, theme })
-    }
-
-    /// Languages contributed by live plugins (for runtime language registration).
-    pub fn languages(&self) -> Vec<LanguageConfig> {
-        self.plugins
-            .read()
-            .values()
-            .filter(|p| p.is_live())
-            .flat_map(|p| p.registrations.lock().languages.clone())
-            .collect()
-    }
-
-    /// Deactivates every plugin (also done on drop).
-    pub fn shutdown(&self) {
-        for plugin in self.plugins.read().values() {
-            if let Some(mut rt) = plugin.runtime.lock().take() {
-                rt.deactivate();
-            }
-        }
-    }
-
-    // ---- internals ----
-
-    fn get(&self, id: &str) -> IdeResult<Arc<LoadedPlugin>> {
-        let plugin =
-            self.plugins.read().get(id).cloned().ok_or_else(|| IdeError::not_found(format!("no plugin {id:?}")))?;
-        if plugin.dev_root.as_deref().is_some_and(|root| !(self.project_policy.read())(root)) {
-            return Err(IdeError::unavailable("Project is in Restricted Mode"));
-        }
-        Ok(plugin)
-    }
-
-    fn is_loaded_from(&self, dir: &Path) -> bool {
-        self.plugins.read().values().any(|p| p.dir == dir)
-    }
-
-    /// Loads one package and starts it unless disabled. Returns the plugin id.
-    fn load_dir(&self, dir: &Path, source: PluginSource, dev_root: Option<PathBuf>) -> String {
-        let (manifest, static_regs, error) = match PluginManifest::load(dir) {
-            Ok(m) => match static_contributions(dir, &m) {
-                Ok(regs) => (m, regs, None),
-                Err(e) => (m, Registrations::default(), Some(e)),
-            },
-            Err(e) => (placeholder_manifest(dir), Registrations::default(), Some(e)),
-        };
-        let id = manifest.id.clone();
-        let plugin = Arc::new(LoadedPlugin {
-            manifest,
-            dir: dir.to_path_buf(),
-            source,
-            dev_root,
-            registrations: Arc::new(Mutex::new(static_regs.clone())),
-            static_regs,
-            meta: Mutex::new(Meta { status: PluginStatus::Disabled, error: None }),
-            runtime: Mutex::new(None),
-        });
-        {
-            let mut plugins = self.plugins.write();
-            if let Some(existing) = plugins.get(&id) {
-                tracing::warn!(
-                    "plugin {id:?} at {} ignored: already loaded from {}",
-                    dir.display(),
-                    existing.dir.display()
-                );
-                return id;
-            }
-            plugins.insert(id.clone(), plugin.clone());
-        }
-        if let Some(e) = error {
-            tracing::warn!("plugin {}: {e}", dir.display());
-            plugin.set_failed(e);
-        } else if !self.state.lock().disabled.contains(&id) {
-            self.start(&plugin);
-        }
-        id
-    }
-
-    fn unload(&self, id: &str) {
-        let Some(plugin) = self.plugins.write().remove(id) else { return };
-        self.stop(&plugin);
-    }
-
-    fn start(&self, plugin: &Arc<LoadedPlugin>) {
-        *plugin.registrations.lock() = plugin.static_regs.clone();
-        let Some(wasm) = &plugin.manifest.wasm else {
-            *plugin.meta.lock() = Meta { status: PluginStatus::Static, error: None };
-            return;
-        };
-        let started = self.engine.compile(&plugin.dir.join(wasm)).and_then(|component| {
-            let active_files = self.active_files.clone();
-            let setup = RuntimeSetup {
-                plugin_id: plugin.manifest.id.clone(),
-                version: plugin.manifest.version.clone(),
-                permissions: plugin.manifest.permissions.clone(),
-                registrations: plugin.registrations.clone(),
-                sink: self.sink.clone(),
-                active_file: Arc::new(move |client| client.and_then(|c| active_files.lock().get(c).cloned())),
-                limits: self.limits,
-            };
-            let mut rt = Runtime::instantiate(&self.engine, &component, setup)?;
-            match rt.activate() {
-                Ok(fx) => Ok((rt, fx)),
-                Err(CallError::Guest(e)) => Err(format!("activation failed: {e}")),
-                Err(CallError::Trap(e)) => Err(format!("activation {e}")),
-            }
-        });
-        match started {
-            Ok((rt, _fx)) => {
-                *plugin.runtime.lock() = Some(rt);
-                *plugin.meta.lock() = Meta { status: PluginStatus::Active, error: None };
-            }
-            Err(e) => self.fail(plugin, &e, None),
-        }
-    }
-
-    fn stop(&self, plugin: &LoadedPlugin) {
-        if let Some(mut rt) = plugin.runtime.lock().take() {
-            rt.deactivate();
-        }
-    }
-
-    fn fail(&self, plugin: &LoadedPlugin, error: &str, client: Option<&str>) {
-        tracing::warn!(plugin = %plugin.manifest.id, "disabled after failure: {error}");
-        plugin.set_failed(error.to_owned());
-        self.emit(
-            client,
-            PluginEvent::Notification {
-                plugin_id: plugin.manifest.id.clone(),
-                level: NotificationLevel::Error,
-                title: format!("Plugin \u{201c}{}\u{201d} was disabled", plugin.manifest.name),
-                body: error.to_owned(),
-            },
-        );
-        self.emit(None, PluginEvent::CommandsChanged);
-        self.emit_theme_if_owned(&plugin.manifest.id);
-    }
-
-    fn apply_effects(&self, plugin: &LoadedPlugin, fx: CallEffects) {
-        if fx.commands_changed {
-            self.emit(None, PluginEvent::CommandsChanged);
-        }
-        let sel = self.state.lock().theme.clone();
-        if let Some(sel) = sel
-            && sel.plugin == plugin.manifest.id
-            && fx.themes_changed.contains(&sel.theme)
-        {
-            self.emit(None, PluginEvent::ThemeChanged { theme: self.active_theme() });
-        }
-    }
-
-    fn emit_theme_if_owned(&self, id: &str) {
-        let owned = self.state.lock().theme.as_ref().is_some_and(|t| t.plugin == id);
-        if owned {
-            self.emit(None, PluginEvent::ThemeChanged { theme: self.active_theme() });
-        }
-    }
-
-    fn emit(&self, client: Option<&str>, event: PluginEvent) {
-        self.sink.emit(client, event);
-    }
-
-    fn save_state(&self) {
-        let json = serde_json::to_string_pretty(&*self.state.lock()).unwrap_or_default();
-        if let Err(e) = std::fs::write(self.plugins_dir.join(STATE_FILE), json) {
-            tracing::warn!("saving plugin state: {e}");
-        }
-    }
-
-    fn info(&self, p: &LoadedPlugin) -> PluginInfo {
-        let m = &p.manifest;
-        let regs = p.registrations.lock().clone();
-        let meta = p.meta.lock();
-        PluginInfo {
-            id: m.id.clone(),
-            name: m.name.clone(),
-            version: m.version.clone(),
-            description: m.description.clone(),
-            authors: m.authors.clone(),
-            homepage: m.homepage.clone(),
-            change_notes: m.change_notes.clone(),
-            source: p.source,
-            path: p.dir.clone().into(),
-            enabled: !self.state.lock().disabled.contains(&m.id),
-            status: meta.status,
-            error: meta.error.clone(),
-            has_code: m.wasm.is_some(),
-            permissions: m.permissions.clone(),
-            commands: regs.commands,
-            languages: regs
-                .languages
-                .iter()
-                .map(|l| PluginLanguage {
-                    id: l.id.to_string(),
-                    name: l.name.clone(),
-                    extensions: l.extensions.clone(),
-                })
-                .collect(),
-            themes: regs
-                .themes
-                .iter()
-                .map(|t| PluginTheme { id: t.id.clone(), name: t.name.clone(), kind: t.kind })
-                .collect(),
-        }
-    }
-}
-
-impl Drop for PluginHost {
-    fn drop(&mut self) {
-        self.shutdown();
-    }
-}
-
-fn is_hex_color(s: &str) -> bool {
-    s.strip_prefix('#').is_some_and(|h| matches!(h.len(), 3 | 6 | 8) && h.bytes().all(|b| b.is_ascii_hexdigit()))
-}
-
-/// Plugin packages found in `dirs` (first occurrence of an id wins). Invalid
-/// manifests are skipped; packages with missing files carry a `problem`.
-pub fn scan_catalog(dirs: &[PathBuf]) -> Vec<CatalogPlugin> {
-    let mut out: Vec<CatalogPlugin> = Vec::new();
-    for dir in dirs.iter().flat_map(|d| package_dirs(d)) {
-        let Ok(m) = PluginManifest::load(&dir) else { continue };
-        if out.iter().any(|c| c.id == m.id) {
-            continue;
-        }
-        let problem = m
-            .files()
-            .into_iter()
-            .find(|f| !dir.join(f).is_file())
-            .map(|f| format!("{} is missing; build the plugin first", f.display()));
-        out.push(CatalogPlugin {
-            has_code: m.wasm.is_some(),
-            language_count: m.contributes.languages.len() as u32,
-            theme_count: m.contributes.themes.len() as u32,
-            commands: m.contributes.commands.clone(),
-            permissions: m.permissions.clone(),
-            id: m.id,
-            name: m.name,
-            version: m.version,
-            description: m.description,
-            authors: m.authors,
-            homepage: m.homepage,
-            change_notes: m.change_notes,
-            path: dir.into(),
-            problem,
-        });
-    }
-    out.sort_by_key(|a| a.name.to_lowercase());
-    out
-}
-
-/// Subdirectories of `dir` that contain a `plugin.toml`, sorted.
-fn package_dirs(dir: &Path) -> Vec<PathBuf> {
-    let Ok(entries) = std::fs::read_dir(dir) else { return Vec::new() };
-    let mut dirs: Vec<PathBuf> = entries
-        .flatten()
-        .map(|e| e.path())
-        .filter(|p| {
-            p.join(MANIFEST_FILE).is_file()
-                && !p.file_name().and_then(|n| n.to_str()).is_some_and(|n| n.starts_with('.'))
-        })
-        .collect();
-    dirs.sort();
-    dirs
-}
-
-fn static_contributions(dir: &Path, m: &PluginManifest) -> Result<Registrations, String> {
-    let mut regs = Registrations::default();
-    for cmd in &m.contributes.commands {
-        regs.add_command(cmd.clone());
-    }
-    let read = |p: &Path| std::fs::read_to_string(dir.join(p)).map_err(|e| format!("{}: {e}", p.display()));
-    for f in &m.contributes.languages {
-        let cfg = runtime::parse_language(&read(&f.path)?).map_err(|e| format!("{}: {e}", f.path.display()))?;
-        regs.add_language(cfg);
-    }
-    for f in &m.contributes.themes {
-        let mut theme = ThemeDef::parse(&read(&f.path)?).map_err(|e| format!("{}: {e}", f.path.display()))?;
-        if let Some(scheme) = &f.editor_scheme {
-            theme.merge_editor_scheme(&read(scheme)?).map_err(|e| format!("{}: {e}", scheme.display()))?;
-        }
-        regs.add_theme(theme);
-    }
-    Ok(regs)
-}
-
-/// Stand-in for a package whose manifest failed to parse, so it still shows up (as failed).
-fn placeholder_manifest(dir: &Path) -> PluginManifest {
-    let name = dir.file_name().map(|n| n.to_string_lossy().into_owned()).unwrap_or_default();
-    PluginManifest {
-        id: format!("invalid-{}", name.to_lowercase().replace(|c: char| !c.is_ascii_alphanumeric(), "-")),
-        name,
-        version: "0.0.0".into(),
-        description: String::new(),
-        authors: Vec::new(),
-        homepage: None,
-        change_notes: None,
-        openidea_api: API_VERSION.into(),
-        wasm: None,
-        permissions: Vec::new(),
-        contributes: Contributions::default(),
-    }
-}
+pub use wasmtime::component::Component;

crates/ide-plugin/src/manifest.rs

@@ -1,279 +0,0 @@
-//! `plugin.toml`: the plugin package manifest.
-
-use serde::{Deserialize, Serialize};
-use specta::Type;
-use std::path::{Component, Path, PathBuf};
-
-/// Plugin API version implemented by this host (`openidea-api` in the manifest).
-pub const API_VERSION: &str = "0.1";
-pub const MANIFEST_FILE: &str = "plugin.toml";
-
-/// Capabilities a plugin must declare to use the gated host functions.
-#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize, Type)]
-#[serde(rename_all = "kebab-case")]
-pub enum Permission {
-    /// `workspace-root`, `read-file` (inside the project root only).
-    ProjectRead,
-    /// `active-file`.
-    EditorRead,
-    /// `insert-text`, `replace-selection`.
-    EditorWrite,
-}
-
-impl Permission {
-    pub fn as_str(self) -> &'static str {
-        match self {
-            Permission::ProjectRead => "project-read",
-            Permission::EditorRead => "editor-read",
-            Permission::EditorWrite => "editor-write",
-        }
-    }
-}
-
-#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
-#[serde(rename_all = "kebab-case", deny_unknown_fields)]
-pub struct PluginManifest {
-    pub id: String,
-    pub name: String,
-    pub version: String,
-    #[serde(default)]
-    pub description: String,
-    #[serde(default)]
-    pub authors: Vec<String>,
-    #[serde(default)]
-    pub homepage: Option<String>,
-    /// Release notes of this version (Settings › Plugins › What's New).
-    #[serde(default)]
-    pub change_notes: Option<String>,
-    pub openidea_api: String,
-    /// Component file relative to the package directory; absent for
-    /// contribution-only plugins (themes, languages).
-    #[serde(default)]
-    pub wasm: Option<PathBuf>,
-    #[serde(default)]
-    pub permissions: Vec<Permission>,
-    #[serde(default)]
-    pub contributes: Contributions,
-}
-
-#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
-#[serde(rename_all = "kebab-case", deny_unknown_fields)]
-pub struct Contributions {
-    #[serde(default)]
-    pub commands: Vec<CommandDecl>,
-    #[serde(default)]
-    pub languages: Vec<FileDecl>,
-    #[serde(default)]
-    pub themes: Vec<ThemeDecl>,
-}
-
-#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
-#[serde(rename_all = "camelCase")]
-pub struct CommandDecl {
-    pub id: String,
-    pub title: String,
-    #[serde(default)]
-    pub category: Option<String>,
-}
-
-/// A contributed file, relative to the package directory.
-#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(deny_unknown_fields)]
-pub struct FileDecl {
-    pub path: PathBuf,
-}
-
-/// A contributed theme: the UI theme file plus an optional editor colour scheme
-/// whose tokens are merged over it (IntelliJ's `.theme.json` + `.icls`).
-#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(rename_all = "kebab-case", deny_unknown_fields)]
-pub struct ThemeDecl {
-    pub path: PathBuf,
-    #[serde(default)]
-    pub editor_scheme: Option<PathBuf>,
-}
-
-impl PluginManifest {
-    pub fn parse(src: &str) -> Result<Self, String> {
-        let manifest: Self = toml::from_str(src).map_err(|e| e.to_string())?;
-        manifest.validate()?;
-        Ok(manifest)
-    }
-
-    pub fn load(dir: &Path) -> Result<Self, String> {
-        let path = dir.join(MANIFEST_FILE);
-        let src = std::fs::read_to_string(&path).map_err(|e| format!("{}: {e}", path.display()))?;
-        Self::parse(&src).map_err(|e| format!("{}: {e}", path.display()))
-    }
-
-    pub fn validate(&self) -> Result<(), String> {
-        validate_plugin_id(&self.id)?;
-        if self.name.trim().is_empty() {
-            return Err("`name` must not be empty".into());
-        }
-        if !is_version(&self.version) {
-            return Err(format!("`version` must look like 1.2.3, got {:?}", self.version));
-        }
-        if !api_compatible(&self.openidea_api) {
-            return Err(format!(
-                "unsupported openidea-api {:?} (this IDE implements {API_VERSION})",
-                self.openidea_api
-            ));
-        }
-        if let Some(wasm) = &self.wasm {
-            check_relative(wasm, "wasm")?;
-        }
-        let mut seen = std::collections::HashSet::new();
-        for c in &self.contributes.commands {
-            validate_command_id(&c.id)?;
-            if !seen.insert(c.id.as_str()) {
-                return Err(format!("duplicate command id {:?}", c.id));
-            }
-            if c.title.trim().is_empty() {
-                return Err(format!("command {:?} has an empty title", c.id));
-            }
-        }
-        let theme_files = self.contributes.themes.iter().flat_map(|t| std::iter::once(&t.path).chain(&t.editor_scheme));
-        for path in self.contributes.languages.iter().map(|f| &f.path).chain(theme_files) {
-            check_relative(path, "contributes path")?;
-        }
-        Ok(())
-    }
-
-    /// Every file of the package besides the manifest (what an install copies).
-    pub fn files(&self) -> Vec<&Path> {
-        let mut files: Vec<&Path> = self.wasm.iter().map(PathBuf::as_path).collect();
-        files.extend(self.contributes.languages.iter().map(|f| f.path.as_path()));
-        for t in &self.contributes.themes {
-            files.push(t.path.as_path());
-            files.extend(t.editor_scheme.as_deref());
-        }
-        files
-    }
-
-    pub fn has(&self, p: Permission) -> bool {
-        self.permissions.contains(&p)
-    }
-}
-
-/// `[a-z0-9][a-z0-9_-]*`, at most 64 chars (no dots: it is one segment of an action id).
-pub fn validate_plugin_id(id: &str) -> Result<(), String> {
-    validate_ident(id, "plugin id", false)
-}
-
-/// `[a-z0-9][a-z0-9._-]*`, at most 64 chars.
-pub fn validate_command_id(id: &str) -> Result<(), String> {
-    validate_ident(id, "command id", true)
-}
-
-fn validate_ident(id: &str, what: &str, dots: bool) -> Result<(), String> {
-    let ok_first = id.chars().next().is_some_and(|c| c.is_ascii_lowercase() || c.is_ascii_digit());
-    let ok_rest =
-        id.chars().all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || c == '-' || c == '_' || (dots && c == '.'));
-    if ok_first && ok_rest && id.len() <= 64 {
-        Ok(())
-    } else {
-        let allowed = if dots { "a-z, 0-9, '.', '-', '_'" } else { "a-z, 0-9, '-', '_'" };
-        Err(format!("invalid {what} {id:?}: use {allowed}, starting with a letter or digit (max 64)"))
-    }
-}
-
-fn is_version(v: &str) -> bool {
-    let core = v.split(['-', '+']).next().unwrap_or_default();
-    let parts: Vec<&str> = core.split('.').collect();
-    parts.len() == 3 && parts.iter().all(|p| !p.is_empty() && p.bytes().all(|b| b.is_ascii_digit()))
-}
-
-/// `0.1` and `0.1.x` are compatible with API 0.1 (pre-1.0: minor is breaking).
-fn api_compatible(v: &str) -> bool {
-    v == API_VERSION || v.strip_prefix(API_VERSION).is_some_and(|rest| rest.starts_with('.'))
-}
-
-/// Package paths must stay inside the package directory.
-fn check_relative(path: &Path, what: &str) -> Result<(), String> {
-    let ok = !path.as_os_str().is_empty() && path.components().all(|c| matches!(c, Component::Normal(_)));
-    if ok { Ok(()) } else { Err(format!("{what} {:?} must be a relative path inside the plugin", path.display())) }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    const FULL: &str = r#"
-        id = "hello"
-        name = "Hello"
-        version = "0.1.0"
-        description = "Says hello"
-        authors = ["A"]
-        openidea-api = "0.1"
-        wasm = "dist/plugin.wasm"
-        permissions = ["project-read", "editor-write"]
-
-        [[contributes.commands]]
-        id = "say.hi"
-        title = "Say Hi"
-        category = "Hello"
-
-        [[contributes.themes]]
-        path = "themes/dark.json"
-        editor-scheme = "themes/dark.scheme.json"
-    "#;
-
-    #[test]
-    fn parses_full_manifest() {
-        let m = PluginManifest::parse(FULL).unwrap();
-        assert_eq!(m.id, "hello");
-        assert_eq!(m.permissions, vec![Permission::ProjectRead, Permission::EditorWrite]);
-        assert_eq!(m.contributes.commands[0].category.as_deref(), Some("Hello"));
-        assert_eq!(
-            m.files(),
-            vec![Path::new("dist/plugin.wasm"), Path::new("themes/dark.json"), Path::new("themes/dark.scheme.json")]
-        );
-        assert!(m.has(Permission::EditorWrite) && !m.has(Permission::EditorRead));
-    }
-
-    #[test]
-    fn minimal_contribution_only_manifest() {
-        let m =
-            PluginManifest::parse("id = \"t\"\nname = \"T\"\nversion = \"1.0.0\"\nopenidea-api = \"0.1.3\"").unwrap();
-        assert!(m.wasm.is_none() && m.permissions.is_empty());
-    }
-
-    fn err(src: &str) -> String {
-        PluginManifest::parse(src).unwrap_err()
-    }
-
-    #[test]
-    fn rejects_invalid_manifests() {
-        let base = |extra: &str, id: &str, api: &str| {
-            format!("id = \"{id}\"\nname = \"N\"\nversion = \"1.0.0\"\nopenidea-api = \"{api}\"\n{extra}")
-        };
-        assert!(err(&base("", "Bad.Id", "0.1")).contains("invalid plugin id"));
-        assert!(err(&base("", "ok", "0.2")).contains("unsupported openidea-api"));
-        assert!(err(&base("", "ok", "0.10")).contains("unsupported openidea-api"));
-        assert!(err(&base("permissions = [\"network\"]", "ok", "0.1")).contains("unknown variant"));
-        assert!(err(&base("wasm = \"../evil.wasm\"", "ok", "0.1")).contains("relative path"));
-        assert!(err(&base("wasm = \"/abs.wasm\"", "ok", "0.1")).contains("relative path"));
-        assert!(err(&base("bogus = 1", "ok", "0.1")).contains("unknown field"));
-        let dup =
-            "[[contributes.commands]]\nid = \"a\"\ntitle = \"A\"\n[[contributes.commands]]\nid = \"a\"\ntitle = \"B\"";
-        assert!(err(&base(dup, "ok", "0.1")).contains("duplicate command"));
-        let traversal = "[[contributes.languages]]\npath = \"a/../../x.toml\"";
-        assert!(err(&base(traversal, "ok", "0.1")).contains("relative path"));
-        let scheme_escape = "[[contributes.themes]]\npath = \"t.json\"\neditor-scheme = \"../s.json\"";
-        assert!(err(&base(scheme_escape, "ok", "0.1")).contains("relative path"));
-        assert!(err("id = \"ok\"\nname = \"N\"\nversion = \"1.0\"\nopenidea-api = \"0.1\"").contains("version"));
-        assert!(err("id = \"ok\"\nname = \" \"\nversion = \"1.0.0\"\nopenidea-api = \"0.1\"").contains("name"));
-    }
-
-    #[test]
-    fn ident_rules() {
-        assert!(validate_command_id("word-count.v2_x").is_ok());
-        assert!(validate_command_id("-x").is_err());
-        assert!(validate_command_id("").is_err());
-        assert!(validate_command_id(&"a".repeat(65)).is_err());
-        assert!(validate_plugin_id("a.b").is_err());
-        assert!(is_version("1.2.3-beta.1+build"));
-        assert!(!is_version("1.2.x"));
-    }
-}

crates/ide-plugin/src/package.rs

@@ -1,74 +0,0 @@
-//! Plugin packages on disk: a folder, its `plugin.toml`, or a `.zip` of the folder.
-
-use crate::MANIFEST_FILE;
-use ide_core::{IdeError, IdeResult};
-use std::fs::{self, File};
-use std::io::{self, BufReader, Read};
-use std::path::{Path, PathBuf};
-
-/// Far above any real package; stops a zip bomb before it fills the disk.
-const MAX_ENTRIES: usize = 10_000;
-const MAX_UNPACKED_BYTES: u64 = 1024 * 1024 * 1024;
-
-pub(crate) fn is_zip(path: &Path) -> bool {
-    path.extension().is_some_and(|e| e.eq_ignore_ascii_case("zip"))
-}
-
-fn invalid_zip(zip: &Path, reason: impl std::fmt::Display) -> IdeError {
-    IdeError::invalid(format!("{} is not a valid plugin archive: {reason}", zip.display()))
-}
-
-/// Unpacks `zip` into `dest` and returns the package folder inside it. Refuses the
-/// whole archive when an entry would leave `dest` or is a symbolic link.
-pub(crate) fn unpack_zip(zip: &Path, dest: &Path) -> IdeResult<PathBuf> {
-    let mut archive = zip::ZipArchive::new(BufReader::new(File::open(zip)?)).map_err(|e| invalid_zip(zip, e))?;
-    if archive.len() > MAX_ENTRIES {
-        return Err(invalid_zip(zip, format!("more than {MAX_ENTRIES} entries")));
-    }
-    let mut budget = MAX_UNPACKED_BYTES;
-    for i in 0..archive.len() {
-        let mut entry = archive.by_index(i).map_err(|e| invalid_zip(zip, e))?;
-        let name = entry.name().to_owned();
-        let Some(rel) = entry.enclosed_name() else {
-            return Err(invalid_zip(zip, format!("unsafe path {name:?}")));
-        };
-        if entry.is_symlink() {
-            return Err(invalid_zip(zip, format!("symbolic link {name:?}")));
-        }
-        let out = dest.join(rel);
-        if entry.is_dir() {
-            fs::create_dir_all(&out)?;
-            continue;
-        }
-        if let Some(parent) = out.parent() {
-            fs::create_dir_all(parent)?;
-        }
-        // One byte over the budget tells a full budget from a file that exactly fits.
-        let written =
-            io::copy(&mut (&mut entry).take(budget + 1), &mut File::create(&out)?).map_err(|e| invalid_zip(zip, e))?;
-        if written > budget {
-            return Err(invalid_zip(zip, "it unpacks to more than 1 GB"));
-        }
-        budget -= written;
-    }
-    package_root(dest).ok_or_else(|| {
-        IdeError::invalid(format!(
-            "{} is not an OpenIDEA plugin: no {MANIFEST_FILE} at its root or in its only folder",
-            zip.display()
-        ))
-    })
-}
-
-/// `dir` itself, or its only folder as when a zip holds the package folder.
-/// Archiver metadata (`__MACOSX`, dot files) does not count as a second folder.
-fn package_root(dir: &Path) -> Option<PathBuf> {
-    if dir.join(MANIFEST_FILE).is_file() {
-        return Some(dir.to_path_buf());
-    }
-    let mut folders = fs::read_dir(dir).ok()?.flatten().map(|e| e.path()).filter(|p| {
-        let name = p.file_name().unwrap_or_default().to_string_lossy();
-        p.is_dir() && !name.starts_with('.') && name != "__MACOSX"
-    });
-    let only = folders.next().filter(|_| folders.next().is_none())?;
-    only.join(MANIFEST_FILE).is_file().then_some(only)
-}

crates/ide-plugin/src/types.rs

@@ -1,11 +1,8 @@
-//! UI-facing types and the event stream.
+//! Types shared by the runtime and the host.
 
-use crate::manifest::{CommandDecl, Permission};
-use crate::theme::{ThemeDef, ThemeKind};
 use serde::{Deserialize, Serialize};
 use specta::Type;
-use std::path::{Path, PathBuf};
-use std::sync::Arc;
+use std::path::PathBuf;
 use std::time::Duration;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
@@ -16,156 +13,457 @@ pub enum NotificationLevel {
     Error,
 }
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
-#[serde(rename_all = "camelCase")]
-pub enum PluginSource {
-    /// Installed under `<app-data>/plugins/<id>/`.
-    Installed,
-    /// Loaded from `<project>/.openidea/plugins/<dir>/` while that project is open.
-    Dev,
+/// The focused editor of the window a command came from.
+#[derive(Clone, Debug, Default)]
+pub struct EditorContext {
+    pub path: PathBuf,
+    pub language: String,
+    /// Selections when the command was invoked (cursors are empty ranges).
+    pub selections: Vec<ide_core::Range>,
 }
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
-#[serde(rename_all = "camelCase")]
-pub enum PluginStatus {
-    /// Code loaded and activated.
-    Active,
-    /// No code; static contributions only.
-    Static,
-    Disabled,
-    /// Failed to load, or trapped and was disabled for this session (see `error`).
-    Failed,
-}
-
-#[derive(Clone, Debug, Serialize, Deserialize, Type)]
-#[serde(rename_all = "camelCase")]
-pub struct PluginLanguage {
-    pub id: String,
-    pub name: String,
-    pub extensions: Vec<String>,
-}
-
-#[derive(Clone, Debug, Serialize, Deserialize, Type)]
-#[serde(rename_all = "camelCase")]
-pub struct PluginTheme {
-    pub id: String,
-    pub name: String,
-    pub kind: ThemeKind,
-}
-
-#[derive(Clone, Debug, Serialize, Deserialize, Type)]
-#[serde(rename_all = "camelCase")]
-pub struct PluginInfo {
-    pub id: String,
-    pub name: String,
-    pub version: String,
-    pub description: String,
-    pub authors: Vec<String>,
-    pub homepage: Option<String>,
-    pub change_notes: Option<String>,
-    pub source: PluginSource,
-    /// Package directory.
-    pub path: ide_core::IpcPath,
-    pub enabled: bool,
-    pub status: PluginStatus,
-    pub error: Option<String>,
-    pub has_code: bool,
-    pub permissions: Vec<Permission>,
-    /// Commands contributed while enabled (manifest + registered at runtime).
-    pub commands: Vec<CommandDecl>,
-    pub languages: Vec<PluginLanguage>,
-    pub themes: Vec<PluginTheme>,
-}
-
-/// A plugin package available for installation from a local catalog
-/// directory (the samples shipped with the IDE). Not installed by listing it.
-#[derive(Clone, Debug, Serialize, Deserialize, Type)]
-#[serde(rename_all = "camelCase")]
-pub struct CatalogPlugin {
-    pub id: String,
-    pub name: String,
-    pub version: String,
-    pub description: String,
-    pub authors: Vec<String>,
-    pub homepage: Option<String>,
-    pub change_notes: Option<String>,
-    /// Package directory; install with `install_from_path(path)`.
-    pub path: ide_core::IpcPath,
-    pub has_code: bool,
-    pub permissions: Vec<Permission>,
-    pub commands: Vec<CommandDecl>,
-    pub language_count: u32,
-    pub theme_count: u32,
-    /// Why the package cannot be installed as is (e.g. its WASM is not built).
-    pub problem: Option<String>,
-}
-
-#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
-#[serde(rename_all = "camelCase")]
-pub struct ActiveTheme {
-    pub plugin_id: String,
-    pub theme: ThemeDef,
-}
-
-#[derive(Clone, Debug, Serialize, Deserialize, Type)]
-#[serde(rename_all = "camelCase")]
-pub struct PluginsSnapshot {
-    pub plugins: Vec<PluginInfo>,
-    pub active_theme: Option<ActiveTheme>,
-}
-
-/// Backend → UI notifications (Tauri event `ide://plugin`).
-#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
-#[serde(tag = "type", rename_all = "camelCase")]
-pub enum PluginEvent {
-    /// Plugins, their status or their commands changed: re-fetch `plugin_list`.
-    CommandsChanged,
-    #[serde(rename_all = "camelCase")]
-    Notification { plugin_id: String, level: NotificationLevel, title: String, body: String },
-    #[serde(rename_all = "camelCase")]
-    InsertText { plugin_id: String, text: String },
-    #[serde(rename_all = "camelCase")]
-    ReplaceSelection { plugin_id: String, text: String },
-    #[serde(rename_all = "camelCase")]
-    ThemeChanged { theme: Option<ActiveTheme> },
-}
-
-/// Delivers events to the UI. `client` is the window that invoked the plugin
-/// (`None` = broadcast, e.g. during activation).
-pub trait PluginEventSink: Send + Sync {
-    fn emit(&self, client: Option<&str>, event: PluginEvent);
-}
-
-impl<F: Fn(Option<&str>, PluginEvent) + Send + Sync> PluginEventSink for F {
-    fn emit(&self, client: Option<&str>, event: PluginEvent) {
-        self(client, event)
-    }
-}
-
-pub type BufferText = Arc<dyn Fn(&Path) -> Option<String> + Send + Sync>;
-
-/// Where a command runs: the invoking window and its project.
-#[derive(Clone, Default)]
+/// Where a command or event batch comes from: the window and its project.
+#[derive(Clone, Debug, Default)]
 pub struct Invocation {
     pub client: Option<String>,
     pub workspace_root: Option<PathBuf>,
-    /// Unsaved editor contents win over disk for `read-file`.
-    pub buffer_text: Option<BufferText>,
+    pub editor: Option<EditorContext>,
 }
 
-/// Per-call resource limits for plugin code.
+/// A failed host call, as the plugin sees it (WIT `types.error`).
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum HostError {
+    /// Not granted; names the capability.
+    Denied(String),
+    /// The document changed since the version an edit was made for.
+    Stale,
+    NotFound(String),
+    Invalid(String),
+    Cancelled,
+    Failed(String),
+}
+
+impl std::fmt::Display for HostError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Denied(c) => write!(f, "permission denied: {c} is not granted"),
+            Self::Stale => f.write_str("the document changed"),
+            Self::NotFound(m) => write!(f, "not found: {m}"),
+            Self::Invalid(m) => write!(f, "invalid: {m}"),
+            Self::Cancelled => f.write_str("cancelled"),
+            Self::Failed(m) => f.write_str(m),
+        }
+    }
+}
+
+/// A plugin's status bar item.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct StatusItem {
+    pub text: String,
+    pub tooltip: Option<String>,
+    /// One of the plugin's commands, run on click.
+    pub command: Option<String>,
+}
+
+/// Kinds of workbench events a plugin can subscribe to (`on-event:<kind>`).
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize, Type)]
+#[serde(rename_all = "kebab-case")]
+pub enum EventKind {
+    FileOpened,
+    FileSaved,
+    EditorFocused,
+    ActionPerformed,
+    VcsChanged,
+    Scheduled,
+}
+
+impl EventKind {
+    pub const ALL: [Self; 6] = [
+        Self::FileOpened,
+        Self::FileSaved,
+        Self::EditorFocused,
+        Self::ActionPerformed,
+        Self::VcsChanged,
+        Self::Scheduled,
+    ];
+
+    pub fn name(self) -> &'static str {
+        match self {
+            Self::FileOpened => "file-opened",
+            Self::FileSaved => "file-saved",
+            Self::EditorFocused => "editor-focused",
+            Self::ActionPerformed => "action-performed",
+            Self::VcsChanged => "vcs-changed",
+            Self::Scheduled => "scheduled",
+        }
+    }
+
+    pub fn parse(s: &str) -> Option<Self> {
+        Self::ALL.into_iter().find(|k| k.name() == s)
+    }
+
+    /// The capability a subscription needs (`None`: `scheduled`, which the
+    /// manifest declares).
+    pub fn capability(self) -> Option<ide_extension::Capability> {
+        match self {
+            Self::ActionPerformed => Some(ide_extension::Capability::InputEvents),
+            Self::Scheduled => None,
+            _ => Some(ide_extension::Capability::Events),
+        }
+    }
+}
+
+/// How the user started an action.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub enum ActionSource {
+    Keyboard,
+    Menu,
+    Toolbar,
+    ContextMenu,
+    Search,
+    Other,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ActionPerformed {
+    pub action: String,
+    pub title: String,
+    pub source: ActionSource,
+    pub shortcut: Option<String>,
+}
+
+/// A workbench event delivered to plugins.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase", tag = "kind", content = "value")]
+pub enum WorkbenchEvent {
+    FileOpened(String),
+    FileSaved(String),
+    EditorFocused(Option<String>),
+    ActionPerformed(ActionPerformed),
+    VcsChanged(String),
+    Scheduled,
+}
+
+impl WorkbenchEvent {
+    pub fn kind(&self) -> EventKind {
+        match self {
+            Self::FileOpened(_) => EventKind::FileOpened,
+            Self::FileSaved(_) => EventKind::FileSaved,
+            Self::EditorFocused(_) => EventKind::EditorFocused,
+            Self::ActionPerformed(_) => EventKind::ActionPerformed,
+            Self::VcsChanged(_) => EventKind::VcsChanged,
+            Self::Scheduled => EventKind::Scheduled,
+        }
+    }
+}
+
+/// State of the repository containing a project (WIT `vcs.repository-status`).
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub struct RepositoryStatus {
+    pub root: String,
+    pub branch: Option<String>,
+    pub commit: Option<String>,
+    pub upstream: Option<String>,
+    pub ahead: u32,
+    pub behind: u32,
+    pub operation: Option<String>,
+    pub changed_files: u32,
+}
+
+/// Resource limits and supervision policy for plugin code.
 #[derive(Clone, Copy, Debug)]
 pub struct Limits {
     /// Wasm fuel (≈ instructions) per host → plugin call.
     pub fuel: u64,
-    /// Wall-clock limit per call (epoch interruption).
+    /// Wall-clock limit of commands, events, activation and deactivation.
     pub timeout: Duration,
+    /// Wall-clock limit of a call that began a task (`tasks.begin`).
+    pub background: Duration,
+    /// Edit-path calls (syntax): the caller stops waiting after this and the
+    /// result is dropped; the plugin keeps its instance.
+    pub edit_soft: Duration,
+    /// Edit-path calls still running after this are interrupted (the instance
+    /// is rebuilt on next use).
+    pub edit_hard: Duration,
     /// Linear memory cap per plugin.
     pub memory_bytes: usize,
+    /// Wait before restarting after a crash; doubles with each consecutive crash.
+    pub restart_backoff: Duration,
+    /// Consecutive crashes after which the plugin is stopped for the session.
+    pub max_failures: u32,
+    /// Instances unused for this long are reclaimed (`None`: kept).
+    pub idle_timeout: Option<Duration>,
 }
 
 impl Default for Limits {
     fn default() -> Self {
-        Self { fuel: 5_000_000_000, timeout: Duration::from_secs(5), memory_bytes: 256 << 20 }
+        Self {
+            fuel: 5_000_000_000,
+            timeout: Duration::from_secs(5),
+            background: Duration::from_secs(60),
+            edit_soft: Duration::from_millis(50),
+            edit_hard: Duration::from_millis(500),
+            memory_bytes: 256 << 20,
+            restart_backoff: Duration::from_secs(1),
+            max_failures: 3,
+            idle_timeout: Some(Duration::from_secs(300)),
+        }
     }
 }
+
+impl Limits {
+    /// Delay before the restart that follows the `failures`-th consecutive crash.
+    pub fn backoff(&self, failures: u32) -> Duration {
+        let factor = 1u32 << failures.saturating_sub(1).min(6);
+        (self.restart_backoff * factor).min(Duration::from_secs(60).max(self.restart_backoff))
+    }
+}
+
+/// A highlighted range from a plugin's `syntax-provider` (UTF-8 byte offsets).
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct SyntaxToken {
+    pub start: u32,
+    pub end: u32,
+    pub kind: String,
+}
+
+/// A structure-view symbol from a plugin's `syntax-provider` (UTF-8 byte offsets).
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct SyntaxSymbol {
+    pub name: String,
+    pub detail: Option<String>,
+    pub kind: String,
+    pub start: u32,
+    pub end: u32,
+    pub name_start: u32,
+    pub name_end: u32,
+    /// Index of the enclosing symbol in the same list.
+    pub parent: Option<u32>,
+}
+
+/// A foldable line range from a plugin's `syntax-provider`.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct SyntaxFold {
+    pub start_line: u32,
+    pub end_line: u32,
+    pub kind: String,
+}
+
+/// An HTTP request from a plugin (WIT `net.request`); headers may hold
+/// `{{secret:<name>}}` placeholders for the host to fill in.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct HttpRequest {
+    pub method: String,
+    pub url: String,
+    pub headers: Vec<(String, String)>,
+    pub body: Option<Vec<u8>>,
+    pub timeout: Duration,
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub struct HttpResponse {
+    pub status: u16,
+    pub headers: Vec<(String, String)>,
+    pub body: Vec<u8>,
+}
+
+/// What a one-off process printed (WIT `process.output`).
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub struct ProcessOutput {
+    pub status: Option<i32>,
+    pub stdout: String,
+    pub stderr: String,
+}
+
+/// Where `net:` requests may go: the URL's host when it is `https`, or
+/// `http` to the loopback interface.
+pub fn net_host(url: &str) -> Result<String, String> {
+    let (scheme, rest) = url.split_once("://").ok_or_else(|| format!("{url:?} is not an absolute URL"))?;
+    let authority = rest.split(['/', '?', '#']).next().unwrap_or_default();
+    let authority = authority.rsplit_once('@').map_or(authority, |(_, h)| h);
+    let host = if let Some(v6) = authority.strip_prefix('[') {
+        v6.split(']').next().unwrap_or_default().to_owned()
+    } else {
+        authority.split(':').next().unwrap_or_default().to_ascii_lowercase()
+    };
+    if host.is_empty() {
+        return Err(format!("{url:?} has no host"));
+    }
+    let loopback = matches!(host.as_str(), "localhost" | "127.0.0.1" | "::1");
+    match scheme.to_ascii_lowercase().as_str() {
+        "https" => Ok(host),
+        "http" if loopback => Ok(host),
+        "http" => Err(format!("{url:?}: plain http is only allowed to localhost")),
+        other => Err(format!("{url:?}: unsupported scheme {other:?}")),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn net_hosts() {
+        assert_eq!(net_host("https://API.example.com:8443/v1?x").unwrap(), "api.example.com");
+        assert_eq!(net_host("http://localhost:11434/api").unwrap(), "localhost");
+        assert_eq!(net_host("https://user:[email protected]/").unwrap(), "h.io");
+        assert!(net_host("http://example.com/").is_err());
+        assert!(net_host("file:///etc/passwd").is_err());
+        assert!(net_host("example.com").is_err());
+    }
+}
+
+/// The document a provider request is about.
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub struct ProviderDocument {
+    pub path: PathBuf,
+    pub language: String,
+    pub version: u64,
+    pub text: String,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Location {
+    pub path: PathBuf,
+    pub range: ide_core::Range,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct CompletionItem {
+    pub label: String,
+    pub detail: Option<String>,
+    /// WIT `completion-kind` name (`method`, `keyword`, …).
+    pub kind: Option<String>,
+    pub insert_text: String,
+    pub replace: Option<ide_core::Range>,
+    pub sort_text: Option<String>,
+    pub documentation: Option<String>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct InlineSuggestion {
+    pub insert_text: String,
+    pub replace: Option<ide_core::Range>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct CodeAction {
+    pub title: String,
+    pub kind: Option<String>,
+    pub preferred: bool,
+    pub edits: Vec<(PathBuf, Vec<ide_core::TextEdit>)>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct LineMarker {
+    pub line: u32,
+    pub icon: Option<String>,
+    pub tooltip: String,
+    pub target: Option<Location>,
+}
+
+// ---- declarative views (wit/views.wit) ---------------------------------------
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ViewButton {
+    pub id: String,
+    pub label: String,
+    pub icon: Option<String>,
+    pub enabled: bool,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ViewTreeItem {
+    pub key: String,
+    pub parent: Option<String>,
+    pub label: String,
+    pub icon: Option<String>,
+    pub detail: Option<String>,
+    pub expandable: bool,
+    pub expanded: bool,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ViewListItem {
+    pub key: String,
+    pub label: String,
+    pub icon: Option<String>,
+    pub detail: Option<String>,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase", tag = "kind", content = "value")]
+pub enum FieldValue {
+    Text(String),
+    Multiline(String),
+    Checkbox(bool),
+    Choice { options: Vec<String>, selected: String },
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ViewField {
+    pub key: String,
+    pub label: String,
+    pub value: FieldValue,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ViewTable {
+    pub columns: Vec<String>,
+    pub total_rows: u32,
+    pub first_row: u32,
+    pub rows: Vec<Vec<String>>,
+    pub editable: bool,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase", tag = "kind", content = "value")]
+pub enum ViewBody {
+    Message(String),
+    Tree(Vec<ViewTreeItem>),
+    List(Vec<ViewListItem>),
+    Form(Vec<ViewField>),
+    Table(ViewTable),
+    Html(String),
+}
+
+/// What a view or custom editor shows.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct View {
+    pub toolbar: Vec<ViewButton>,
+    pub body: ViewBody,
+    pub status: Option<String>,
+}
+
+/// The table rows the UI shows.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct Viewport {
+    pub first_row: u32,
+    pub rows: u32,
+}
+
+/// A user action in a view.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase", tag = "kind")]
+pub enum ViewEvent {
+    Button { id: String },
+    Activate { key: String },
+    Select { key: String },
+    Expand { key: String },
+    Collapse { key: String },
+    Field { key: String, value: String },
+    Cell { row: u32, column: u32, value: String },
+    InsertRow { before: u32 },
+    DeleteRows { rows: Vec<u32> },
+    Message { text: String },
+}

crates/ide-plugin/src/wit_host.rs

@@ -0,0 +1,662 @@
+//! The host side of the `openidea:[email protected]` world: bindings, resource
+//! types and the implementation of every import. Capabilities are checked
+//! here; a missing one returns `error::denied` (the plugin can degrade).
+
+use crate::runtime::{StoreData, clip};
+use crate::sandbox;
+use crate::types::{EditorContext, EventKind, HostError, HttpRequest, NotificationLevel, StatusItem, net_host};
+use ide_extension::Capability;
+use std::path::{Path, PathBuf};
+use std::time::{Duration, Instant};
+use wasmtime::component::Resource;
+
+pub(crate) mod bindings {
+    wasmtime::component::bindgen!({
+        world: "plugin",
+        path: "../../wit",
+        imports: { default: trappable },
+        with: {
+            "openidea:plugin/workspace.project": super::ProjectRes,
+            "openidea:plugin/editor.text-editor": super::EditorRes,
+            "openidea:plugin/invocation.invocation": super::InvocationRes,
+            "openidea:plugin/tasks.task": super::TaskRes,
+        },
+    });
+}
+
+/// The optional `syntax-provider` export, bound on its own when present.
+pub(crate) mod syntax_bindings {
+    wasmtime::component::bindgen!({
+        world: "plugin-syntax",
+        path: "../../wit",
+        imports: { default: trappable },
+        with: {
+            "openidea:plugin/types": super::bindings::openidea::plugin::types,
+            "openidea:plugin/log": super::bindings::openidea::plugin::log,
+            "openidea:plugin/ui": super::bindings::openidea::plugin::ui,
+            "openidea:plugin/storage": super::bindings::openidea::plugin::storage,
+            "openidea:plugin/workspace": super::bindings::openidea::plugin::workspace,
+            "openidea:plugin/editor": super::bindings::openidea::plugin::editor,
+            "openidea:plugin/invocation": super::bindings::openidea::plugin::invocation,
+            "openidea:plugin/vcs": super::bindings::openidea::plugin::vcs,
+            "openidea:plugin/events": super::bindings::openidea::plugin::events,
+            "openidea:plugin/tasks": super::bindings::openidea::plugin::tasks,
+            "openidea:plugin/diagnostics": super::bindings::openidea::plugin::diagnostics,
+            "openidea:plugin/net": super::bindings::openidea::plugin::net,
+            "openidea:plugin/secrets": super::bindings::openidea::plugin::secrets,
+            "openidea:plugin/process": super::bindings::openidea::plugin::process,
+            "openidea:plugin/views": super::bindings::openidea::plugin::views,
+            "openidea:plugin/settings": super::bindings::openidea::plugin::settings,
+        },
+    });
+}
+
+/// The optional `providers` export.
+pub(crate) mod providers_bindings {
+    wasmtime::component::bindgen!({
+        world: "plugin-providers",
+        path: "../../wit",
+        imports: { default: trappable },
+        with: {
+            "openidea:plugin/types": super::bindings::openidea::plugin::types,
+            "openidea:plugin/log": super::bindings::openidea::plugin::log,
+            "openidea:plugin/ui": super::bindings::openidea::plugin::ui,
+            "openidea:plugin/storage": super::bindings::openidea::plugin::storage,
+            "openidea:plugin/workspace": super::bindings::openidea::plugin::workspace,
+            "openidea:plugin/editor": super::bindings::openidea::plugin::editor,
+            "openidea:plugin/invocation": super::bindings::openidea::plugin::invocation,
+            "openidea:plugin/vcs": super::bindings::openidea::plugin::vcs,
+            "openidea:plugin/events": super::bindings::openidea::plugin::events,
+            "openidea:plugin/tasks": super::bindings::openidea::plugin::tasks,
+            "openidea:plugin/diagnostics": super::bindings::openidea::plugin::diagnostics,
+            "openidea:plugin/net": super::bindings::openidea::plugin::net,
+            "openidea:plugin/secrets": super::bindings::openidea::plugin::secrets,
+            "openidea:plugin/process": super::bindings::openidea::plugin::process,
+            "openidea:plugin/views": super::bindings::openidea::plugin::views,
+            "openidea:plugin/settings": super::bindings::openidea::plugin::settings,
+        },
+    });
+}
+
+/// The optional `view-provider` export.
+pub(crate) mod views_bindings {
+    wasmtime::component::bindgen!({
+        world: "plugin-views",
+        path: "../../wit",
+        imports: { default: trappable },
+        with: {
+            "openidea:plugin/types": super::bindings::openidea::plugin::types,
+            "openidea:plugin/log": super::bindings::openidea::plugin::log,
+            "openidea:plugin/ui": super::bindings::openidea::plugin::ui,
+            "openidea:plugin/storage": super::bindings::openidea::plugin::storage,
+            "openidea:plugin/workspace": super::bindings::openidea::plugin::workspace,
+            "openidea:plugin/editor": super::bindings::openidea::plugin::editor,
+            "openidea:plugin/invocation": super::bindings::openidea::plugin::invocation,
+            "openidea:plugin/vcs": super::bindings::openidea::plugin::vcs,
+            "openidea:plugin/events": super::bindings::openidea::plugin::events,
+            "openidea:plugin/tasks": super::bindings::openidea::plugin::tasks,
+            "openidea:plugin/diagnostics": super::bindings::openidea::plugin::diagnostics,
+            "openidea:plugin/net": super::bindings::openidea::plugin::net,
+            "openidea:plugin/secrets": super::bindings::openidea::plugin::secrets,
+            "openidea:plugin/process": super::bindings::openidea::plugin::process,
+            "openidea:plugin/views": super::bindings::openidea::plugin::views,
+            "openidea:plugin/settings": super::bindings::openidea::plugin::settings,
+        },
+    });
+}
+
+use bindings::openidea::plugin::{
+    diagnostics, editor, events, invocation, log, net, process, secrets, settings, storage, tasks, types as wit, ui,
+    vcs, views, workspace,
+};
+
+/// A project handle: its root.
+pub struct ProjectRes {
+    root: PathBuf,
+}
+
+/// The invoking window's focused editor.
+pub struct EditorRes {
+    ctx: EditorContext,
+}
+
+/// The current call's invocation (read from [`StoreData`]).
+pub struct InvocationRes;
+
+pub struct TaskRes {
+    id: u64,
+}
+
+const MAX_EDITS: usize = 10_000;
+const MAX_DIAGNOSTICS: usize = 5_000;
+const MAX_REQUEST_BODY: usize = 8 << 20;
+const MAX_FIND: u32 = 10_000;
+const MAX_STATUS_TEXT: usize = 128;
+
+type Fallible<T> = wasmtime::Result<Result<T, wit::Error>>;
+
+pub(crate) fn to_wit(e: HostError) -> wit::Error {
+    match e {
+        HostError::Denied(c) => wit::Error::Denied(c),
+        HostError::Stale => wit::Error::Stale,
+        HostError::NotFound(m) => wit::Error::NotFound(m),
+        HostError::Invalid(m) => wit::Error::Invalid(m),
+        HostError::Cancelled => wit::Error::Cancelled,
+        HostError::Failed(m) => wit::Error::Failed(m),
+    }
+}
+
+/// A guest's `error` as text (`denied: net:example.com`, `stale`, …).
+impl From<wit::Error> for crate::runtime::GuestError {
+    fn from(e: wit::Error) -> Self {
+        let clip = |m: String| clip(m, crate::runtime::MAX_TITLE * 16);
+        match e {
+            wit::Error::Denied(c) => Self::Denied(clip(c)),
+            wit::Error::Stale => Self::Stale,
+            wit::Error::NotFound(m) => Self::NotFound(clip(m)),
+            wit::Error::Invalid(m) => Self::Invalid(clip(m)),
+            wit::Error::Cancelled => Self::Cancelled,
+            wit::Error::Failed(m) => Self::Failed(clip(m)),
+        }
+    }
+}
+
+fn pos(p: wit::Position) -> ide_core::Pos {
+    ide_core::Pos::new(p.line, p.character)
+}
+
+fn range_to_wit(r: &ide_core::Range) -> wit::Range {
+    wit::Range {
+        start: wit::Position { line: r.start.line, character: r.start.col },
+        end: wit::Position { line: r.end.line, character: r.end.col },
+    }
+}
+
+impl StoreData {
+    fn require(&self, cap: Capability) -> Result<(), wit::Error> {
+        if self.granted.iter().any(|g| g.covers(&cap)) { Ok(()) } else { Err(wit::Error::Denied(cap.to_string())) }
+    }
+
+    fn client(&self) -> Option<&str> {
+        self.invocation.client.as_deref()
+    }
+
+    fn push<T: Send + 'static>(&mut self, value: T) -> wasmtime::Result<Resource<T>> {
+        Ok(self.table.push(value)?)
+    }
+
+    pub(crate) fn new_invocation(&mut self) -> wasmtime::Result<Resource<InvocationRes>> {
+        self.push(InvocationRes)
+    }
+
+    pub(crate) fn drop_invocation(&mut self, res: Resource<InvocationRes>) {
+        let _ = self.table.delete(res);
+    }
+}
+
+impl wit::Host for StoreData {}
+
+impl log::Host for StoreData {
+    fn log(&mut self, level: wit::LogLevel, message: String) -> wasmtime::Result<()> {
+        let id = &self.plugin_id;
+        let message = clip(message, crate::runtime::MAX_TEXT);
+        match level {
+            wit::LogLevel::Trace => tracing::trace!(plugin = %id, "{message}"),
+            wit::LogLevel::Debug => tracing::debug!(plugin = %id, "{message}"),
+            wit::LogLevel::Info => tracing::info!(plugin = %id, "{message}"),
+            wit::LogLevel::Warn => tracing::warn!(plugin = %id, "{message}"),
+            wit::LogLevel::Error => tracing::error!(plugin = %id, "{message}"),
+        }
+        Ok(())
+    }
+}
+
+impl ui::Host for StoreData {
+    fn show_notification(
+        &mut self,
+        level: wit::NotificationLevel,
+        title: String,
+        body: String,
+    ) -> wasmtime::Result<()> {
+        let level = match level {
+            wit::NotificationLevel::Info => NotificationLevel::Info,
+            wit::NotificationLevel::Warning => NotificationLevel::Warning,
+            wit::NotificationLevel::Error => NotificationLevel::Error,
+        };
+        let max = crate::runtime::MAX_TITLE;
+        self.host.notify(self.client(), level, clip(title, max), clip(body, 16 << 10));
+        Ok(())
+    }
+
+    fn set_status_item(&mut self, id: String, item: ui::StatusItem) -> wasmtime::Result<()> {
+        let item = StatusItem {
+            text: clip(item.text, MAX_STATUS_TEXT),
+            tooltip: item.tooltip.map(|t| clip(t, 1024)),
+            command: item.command.map(|c| clip(c, 128)),
+        };
+        self.host.status_item(&clip(id, 64), Some(item));
+        Ok(())
+    }
+
+    fn remove_status_item(&mut self, id: String) -> wasmtime::Result<()> {
+        self.host.status_item(&clip(id, 64), None);
+        Ok(())
+    }
+}
+
+impl storage::Host for StoreData {
+    fn get(&mut self, key: String) -> Fallible<Option<String>> {
+        if let Err(e) = self.require(Capability::Storage) {
+            return Ok(Err(e));
+        }
+        Ok(self.host.storage_get(&key).map_err(to_wit))
+    }
+
+    fn set(&mut self, key: String, value: String) -> Fallible<()> {
+        if let Err(e) = self.require(Capability::Storage) {
+            return Ok(Err(e));
+        }
+        Ok(self.host.storage_set(&key, Some(value)).map_err(to_wit))
+    }
+
+    fn delete(&mut self, key: String) -> Fallible<()> {
+        if let Err(e) = self.require(Capability::Storage) {
+            return Ok(Err(e));
+        }
+        Ok(self.host.storage_set(&key, None).map_err(to_wit))
+    }
+
+    fn keys(&mut self, prefix: String) -> Fallible<Vec<String>> {
+        if let Err(e) = self.require(Capability::Storage) {
+            return Ok(Err(e));
+        }
+        Ok(self.host.storage_keys(&prefix).map_err(to_wit))
+    }
+}
+
+impl workspace::Host for StoreData {
+    fn projects(&mut self) -> Fallible<Vec<Resource<ProjectRes>>> {
+        if let Err(e) = self.require(Capability::ProjectRead) {
+            return Ok(Err(e));
+        }
+        let mut out = Vec::new();
+        for root in self.host.projects() {
+            out.push(self.push(ProjectRes { root })?);
+        }
+        Ok(Ok(out))
+    }
+}
+
+impl workspace::HostProject for StoreData {
+    fn root(&mut self, this: Resource<ProjectRes>) -> Fallible<String> {
+        if let Err(e) = self.require(Capability::ProjectRead) {
+            return Ok(Err(e));
+        }
+        Ok(Ok(self.table.get(&this)?.root.to_string_lossy().into_owned()))
+    }
+
+    fn read_file(&mut self, this: Resource<ProjectRes>, path: String) -> Fallible<String> {
+        if let Err(e) = self.require(Capability::ProjectRead) {
+            return Ok(Err(e));
+        }
+        let root = self.table.get(&this)?.root.clone();
+        let real = match sandbox::resolve_in_root(&root, &path) {
+            Ok(real) => real,
+            Err(e) => return Ok(Err(wit::Error::Invalid(e))),
+        };
+        if let Some(text) = self.host.buffer_text(&real) {
+            return Ok(Ok(text));
+        }
+        Ok(sandbox::read_text(&real).map_err(wit::Error::Failed))
+    }
+
+    fn find_files(&mut self, this: Resource<ProjectRes>, glob: String, limit: u32) -> Fallible<Vec<String>> {
+        if let Err(e) = self.require(Capability::ProjectRead) {
+            return Ok(Err(e));
+        }
+        let root = self.table.get(&this)?.root.clone();
+        Ok(self.host.find_files(&root, &glob, limit.min(MAX_FIND) as usize).map_err(to_wit))
+    }
+
+    fn drop(&mut self, rep: Resource<ProjectRes>) -> wasmtime::Result<()> {
+        self.table.delete(rep)?;
+        Ok(())
+    }
+}
+
+impl editor::Host for StoreData {}
+
+impl editor::HostTextEditor for StoreData {
+    fn path(&mut self, this: Resource<EditorRes>) -> wasmtime::Result<String> {
+        Ok(self.table.get(&this)?.ctx.path.to_string_lossy().into_owned())
+    }
+
+    fn language(&mut self, this: Resource<EditorRes>) -> wasmtime::Result<String> {
+        Ok(self.table.get(&this)?.ctx.language.clone())
+    }
+
+    fn document(&mut self, this: Resource<EditorRes>) -> Fallible<editor::Document> {
+        if let Err(e) = self.require(Capability::EditorRead) {
+            return Ok(Err(e));
+        }
+        let path = self.table.get(&this)?.ctx.path.clone();
+        Ok(match self.host.document(&path) {
+            Some((version, text)) => Ok(editor::Document { version, text }),
+            None => Err(wit::Error::NotFound(format!("{} is not open", path.display()))),
+        })
+    }
+
+    fn selections(&mut self, this: Resource<EditorRes>) -> Fallible<Vec<wit::Range>> {
+        if let Err(e) = self.require(Capability::EditorRead) {
+            return Ok(Err(e));
+        }
+        Ok(Ok(self.table.get(&this)?.ctx.selections.iter().map(range_to_wit).collect()))
+    }
+
+    fn apply_edits(&mut self, this: Resource<EditorRes>, version: u64, edits: Vec<wit::TextEdit>) -> Fallible<u64> {
+        if let Err(e) = self.require(Capability::EditorWrite) {
+            return Ok(Err(e));
+        }
+        if edits.len() > MAX_EDITS {
+            return Ok(Err(wit::Error::Invalid(format!("more than {MAX_EDITS} edits"))));
+        }
+        let total: usize = edits.iter().map(|e| e.text.len()).sum();
+        if total > crate::runtime::MAX_TEXT * 8 {
+            return Ok(Err(wit::Error::Invalid("edits too large".into())));
+        }
+        let path = self.table.get(&this)?.ctx.path.clone();
+        let edits: Vec<ide_core::TextEdit> = edits
+            .into_iter()
+            .map(|e| ide_core::TextEdit {
+                range: ide_core::Range::new(pos(e.range.start), pos(e.range.end)),
+                new_text: e.text,
+            })
+            .collect();
+        let client = self.invocation.client.clone();
+        Ok(self.host.apply_edits(client.as_deref(), &path, version, edits).map_err(to_wit))
+    }
+
+    fn drop(&mut self, rep: Resource<EditorRes>) -> wasmtime::Result<()> {
+        self.table.delete(rep)?;
+        Ok(())
+    }
+}
+
+impl invocation::Host for StoreData {}
+
+impl invocation::HostInvocation for StoreData {
+    fn project(&mut self, _this: Resource<InvocationRes>) -> wasmtime::Result<Option<Resource<ProjectRes>>> {
+        match self.invocation.workspace_root.clone() {
+            Some(root) => Ok(Some(self.push(ProjectRes { root })?)),
+            None => Ok(None),
+        }
+    }
+
+    fn editor(&mut self, _this: Resource<InvocationRes>) -> wasmtime::Result<Option<Resource<EditorRes>>> {
+        match self.invocation.editor.clone() {
+            Some(ctx) => Ok(Some(self.push(EditorRes { ctx })?)),
+            None => Ok(None),
+        }
+    }
+
+    fn drop(&mut self, rep: Resource<InvocationRes>) -> wasmtime::Result<()> {
+        // Owned by the host for the duration of the call.
+        let _ = rep;
+        Ok(())
+    }
+}
+
+impl vcs::Host for StoreData {
+    fn status(&mut self, project: Resource<ProjectRes>) -> Fallible<Option<vcs::RepositoryStatus>> {
+        if let Err(e) = self.require(Capability::VcsRead) {
+            return Ok(Err(e));
+        }
+        let root = self.table.get(&project)?.root.clone();
+        Ok(self
+            .host
+            .vcs_status(&root)
+            .map(|s| {
+                s.map(|s| vcs::RepositoryStatus {
+                    root: s.root,
+                    branch: s.branch,
+                    commit: s.commit,
+                    upstream: s.upstream,
+                    ahead: s.ahead,
+                    behind: s.behind,
+                    operation: s.operation,
+                    changed_files: s.changed_files,
+                })
+            })
+            .map_err(to_wit))
+    }
+
+    fn fetch(&mut self, project: Resource<ProjectRes>) -> Fallible<()> {
+        if let Err(e) = self.require(Capability::VcsWrite) {
+            return Ok(Err(e));
+        }
+        let root = self.table.get(&project)?.root.clone();
+        let token = self.cancel.token();
+        Ok(self.host.vcs_fetch(&root, &token).map_err(to_wit))
+    }
+}
+
+fn kind_from_wit(k: events::EventKind) -> EventKind {
+    match k {
+        events::EventKind::FileOpened => EventKind::FileOpened,
+        events::EventKind::FileSaved => EventKind::FileSaved,
+        events::EventKind::EditorFocused => EventKind::EditorFocused,
+        events::EventKind::ActionPerformed => EventKind::ActionPerformed,
+        events::EventKind::VcsChanged => EventKind::VcsChanged,
+        events::EventKind::Scheduled => EventKind::Scheduled,
+    }
+}
+
+impl events::Host for StoreData {
+    fn subscribe(&mut self, kind: events::EventKind) -> Fallible<()> {
+        let kind = kind_from_wit(kind);
+        if let Some(cap) = kind.capability()
+            && let Err(e) = self.require(cap)
+        {
+            return Ok(Err(e));
+        }
+        self.host.subscribe(kind, true);
+        Ok(Ok(()))
+    }
+
+    fn unsubscribe(&mut self, kind: events::EventKind) -> wasmtime::Result<()> {
+        self.host.subscribe(kind_from_wit(kind), false);
+        Ok(())
+    }
+}
+
+impl tasks::Host for StoreData {
+    fn begin(&mut self, title: String, cancellable: bool) -> wasmtime::Result<Resource<TaskRes>> {
+        let token = self.cancel.token();
+        let id = self.host.task_begin(self.client(), clip(title, crate::runtime::MAX_TITLE), cancellable, token);
+        self.open_tasks.push(id);
+        // The call may now run for the background budget.
+        let extended = self.call_started + self.limits.background;
+        if extended > self.deadline {
+            self.deadline = extended;
+            self.timeout = self.limits.background;
+        }
+        self.push(TaskRes { id })
+    }
+}
+
+impl tasks::HostTask for StoreData {
+    fn report(
+        &mut self,
+        this: Resource<TaskRes>,
+        done: u32,
+        total: Option<u32>,
+        message: Option<String>,
+    ) -> wasmtime::Result<()> {
+        let id = self.table.get(&this)?.id;
+        let now = Instant::now();
+        // At most ~10 updates per second reach the UI.
+        if self.last_report.is_none_or(|t| now.duration_since(t).as_millis() >= 100) || total.is_some_and(|t| done >= t)
+        {
+            self.last_report = Some(now);
+            self.host.task_report(id, done, total, message.map(|m| clip(m, 256)));
+        }
+        Ok(())
+    }
+
+    fn is_cancelled(&mut self, this: Resource<TaskRes>) -> wasmtime::Result<bool> {
+        let id = self.table.get(&this)?.id;
+        Ok(self.cancel.token().is_cancelled() || self.host.task_cancelled(id))
+    }
+
+    fn drop(&mut self, rep: Resource<TaskRes>) -> wasmtime::Result<()> {
+        let id = self.table.delete(rep)?.id;
+        self.open_tasks.retain(|t| *t != id);
+        self.host.task_end(id);
+        Ok(())
+    }
+}
+
+impl StoreData {
+    /// What is left of the running call's wall-clock budget (host operations
+    /// can't be interrupted by the epoch callback, so they get this as timeout).
+    fn remaining(&self) -> Duration {
+        self.deadline.saturating_duration_since(Instant::now())
+    }
+}
+
+impl diagnostics::Host for StoreData {
+    fn publish(&mut self, path: String, items: Vec<diagnostics::Diagnostic>) -> Fallible<()> {
+        if let Err(e) = self.require(Capability::ProjectRead) {
+            return Ok(Err(e));
+        }
+        let source = self.plugin_id.clone();
+        let items = items
+            .into_iter()
+            .take(MAX_DIAGNOSTICS)
+            .map(|d| ide_core::Diagnostic {
+                range: ide_core::Range::new(pos(d.range.start), pos(d.range.end)),
+                severity: match d.severity {
+                    diagnostics::Severity::Error => ide_core::Severity::Error,
+                    diagnostics::Severity::Warning => ide_core::Severity::Warning,
+                    diagnostics::Severity::Info => ide_core::Severity::Info,
+                    diagnostics::Severity::Hint => ide_core::Severity::Hint,
+                },
+                message: clip(d.message, 4096),
+                source: Some(source.clone()),
+                code: d.code.map(|c| clip(c, 128)),
+                unnecessary: false,
+                deprecated: false,
+                server: Some(source.clone()),
+            })
+            .collect();
+        Ok(self.host.publish_diagnostics(Path::new(&path), items).map_err(to_wit))
+    }
+}
+
+impl net::Host for StoreData {
+    fn fetch(&mut self, req: net::Request) -> Fallible<net::Response> {
+        let host = match net_host(&req.url) {
+            Ok(h) => h,
+            Err(e) => return Ok(Err(wit::Error::Invalid(e))),
+        };
+        if let Err(e) = self.require(Capability::Net(host)) {
+            return Ok(Err(e));
+        }
+        if req.headers.iter().any(|h| h.value.contains("{{secret:"))
+            && let Err(e) = self.require(Capability::Secrets)
+        {
+            return Ok(Err(e));
+        }
+        if req.body.as_ref().is_some_and(|b| b.len() > MAX_REQUEST_BODY) {
+            return Ok(Err(wit::Error::Invalid("request body larger than 8 MiB".into())));
+        }
+        let wanted = Duration::from_millis(u64::from(req.timeout_ms.unwrap_or(30_000)));
+        let request = HttpRequest {
+            method: req.method,
+            url: req.url,
+            headers: req.headers.into_iter().map(|h| (h.name, h.value)).collect(),
+            body: req.body,
+            timeout: wanted.min(self.remaining()),
+        };
+        let token = self.cancel.token();
+        Ok(self
+            .host
+            .fetch(request, &token)
+            .map(|r| net::Response {
+                status: r.status,
+                headers: r.headers.into_iter().map(|(name, value)| net::Header { name, value }).collect(),
+                body: r.body,
+            })
+            .map_err(to_wit))
+    }
+}
+
+impl secrets::Host for StoreData {
+    fn is_set(&mut self, name: String) -> wasmtime::Result<bool> {
+        Ok(self.granted.iter().any(|g| g.covers(&Capability::Secrets)) && self.host.secret_is_set(&name))
+    }
+}
+
+impl process::Host for StoreData {
+    fn run(
+        &mut self,
+        program: String,
+        args: Vec<String>,
+        cwd: Option<Resource<ProjectRes>>,
+        stdin: Option<String>,
+    ) -> Fallible<process::Output> {
+        if let Err(e) = self.require(Capability::Process(program.clone())) {
+            return Ok(Err(e));
+        }
+        let cwd = match &cwd {
+            Some(p) => Some(self.table.get(p)?.root.clone()),
+            None => None,
+        };
+        let token = self.cancel.token();
+        let timeout = self.remaining();
+        Ok(self
+            .host
+            .run_process(&program, args, cwd.as_deref(), stdin, &token, timeout)
+            .map(|o| process::Output { status: o.status, stdout: o.stdout, stderr: o.stderr })
+            .map_err(to_wit))
+    }
+}
+
+impl views::Host for StoreData {
+    fn refresh(&mut self, view: String) -> wasmtime::Result<()> {
+        self.host.refresh_view(&clip(view, 64));
+        Ok(())
+    }
+
+    fn post_message(&mut self, view: String, message: String) -> Fallible<()> {
+        if message.len() > MAX_VIEW_MESSAGE {
+            return Ok(Err(wit::Error::Invalid(format!("messages are limited to {MAX_VIEW_MESSAGE} bytes"))));
+        }
+        Ok(self.host.post_view_message(&clip(view, 64), message).map_err(to_wit))
+    }
+
+    fn open_terminal(&mut self, title: String, program: String, args: Vec<String>) -> Fallible<()> {
+        if let Err(e) = self.require(Capability::Process(program.clone())) {
+            return Ok(Err(e));
+        }
+        if args.len() > 256 || args.iter().any(|a| a.len() > 4096) {
+            return Ok(Err(wit::Error::Invalid("too many or too long arguments".into())));
+        }
+        let cwd = self.invocation.workspace_root.clone();
+        let client = self.invocation.client.clone();
+        let title = clip(title, crate::runtime::MAX_TITLE);
+        Ok(self.host.open_terminal(client.as_deref(), title, &program, args, cwd.as_deref()).map_err(to_wit))
+    }
+}
+
+impl settings::Host for StoreData {
+    fn get(&mut self, key: String) -> wasmtime::Result<Option<String>> {
+        let root = self.invocation.workspace_root.clone();
+        Ok(self.host.setting(root.as_deref(), &clip(key, 128)))
+    }
+}
+
+impl views_bindings::openidea::plugin::view_types::Host for StoreData {}
+
+/// Largest message between a plugin and its view's frame.
+const MAX_VIEW_MESSAGE: usize = 1 << 20;

crates/ide-plugin/tests/api_compat.rs

@@ -0,0 +1,270 @@
+//! Plugin API versioning (plugins/README.md, "Evolving the plugin API").
+//!
+//! - The `wit/` package version, `ENGINE_VERSION` and `API_VERSION` agree.
+//! - The version check accepts components the host can run and explains the rest.
+//! - Components built for 1.0 link against a host of a later 1.x minor that
+//!   adds functions and interfaces (wasmtime resolves `@1.0.0` names to a
+//!   semver-compatible definition), and the host finds their exports under
+//!   the newer name; a 2.0 host does not link them. The newer host is
+//!   simulated with a linker that stubs every plugin import the component has
+//!   at the newer version, so no copy of the WIT is needed.
+//!
+//! Components: the checked-in `dist/plugin.wasm` of the `hello` fixture, the
+//! official plugins (`plugins/build.sh` rebuilds them).
+
+use ide_plugin::{API_VERSION, PluginEngine, check_api, component_api, host_api};
+use std::path::{Path, PathBuf};
+use wasmtime::component::types::ComponentItem;
+use wasmtime::component::{Component, Linker, ResourceTable, ResourceType};
+use wasmtime::{Config, Engine};
+use wasmtime_wasi::{WasiCtx, WasiCtxView, WasiView};
+
+fn repo() -> PathBuf {
+    Path::new(env!("CARGO_MANIFEST_DIR")).join("../..")
+}
+
+/// Every component the repository builds for users: the official plugins with code, plus the `hello` fixture.
+fn components() -> Vec<PathBuf> {
+    let mut out = vec![repo().join("crates/ide-plugin/tests/fixtures/hello/dist/plugin.wasm")];
+    let official = repo().join("plugins/official");
+    let mut dirs: Vec<_> = std::fs::read_dir(&official).unwrap().map(|e| e.unwrap().path()).collect();
+    dirs.sort();
+    out.extend(dirs.into_iter().map(|d| d.join("dist/plugin.wasm")).filter(|p| p.is_file()));
+    assert!(out.len() >= 9, "expected hello and the official plugins, found {out:?}");
+    out
+}
+
+fn v(s: &str) -> semver::Version {
+    semver::Version::parse(s).unwrap()
+}
+
+#[test]
+fn wit_package_engine_and_api_versions_agree() {
+    let host = host_api();
+    assert_eq!(API_VERSION, format!("{}.{}", host.major, host.minor));
+    let want = format!("package openidea:plugin@{host};");
+    let mut files = 0;
+    for entry in std::fs::read_dir(repo().join("wit")).unwrap() {
+        let path = entry.unwrap().path();
+        if path.extension().is_some_and(|e| e == "wit") {
+            let src = std::fs::read_to_string(&path).unwrap();
+            assert!(src.lines().any(|l| l.trim() == want), "{} does not declare `{want}`", path.display());
+            files += 1;
+        }
+    }
+    assert!(files > 1);
+}
+
+/// The SDK ships its own copy of `wit/` (it builds outside this repository);
+/// it must be the API this host implements.
+#[test]
+fn the_sdk_carries_the_hosts_wit() {
+    let read = |dir: PathBuf| {
+        let mut files: Vec<(String, String)> = std::fs::read_dir(&dir)
+            .unwrap()
+            .map(|e| e.unwrap().path())
+            .filter(|p| p.extension().is_some_and(|e| e == "wit"))
+            .map(|p| (p.file_name().unwrap().to_string_lossy().into_owned(), std::fs::read_to_string(&p).unwrap()))
+            .collect();
+        files.sort();
+        files
+    };
+    let host = read(repo().join("wit"));
+    let sdk = read(repo().join("sdk/rust/openidea-plugin/wit"));
+    let names = |f: &[(String, String)]| f.iter().map(|(n, _)| n.clone()).collect::<Vec<_>>();
+    assert_eq!(names(&sdk), names(&host), "sdk/rust/openidea-plugin/wit has other files than wit/");
+    for ((name, a), (_, b)) in host.iter().zip(&sdk) {
+        assert!(a == b, "sdk/rust/openidea-plugin/wit/{name} differs from wit/{name}: copy wit/ into the SDK");
+    }
+}
+
+#[test]
+fn the_version_check_runs_compatible_components_and_explains_the_rest() {
+    let host = v("1.3.0");
+    for ok in ["1.0.0", "1.3.0", "1.3.7", "1.0.0-rc.1"] {
+        assert_eq!(check_api(&v(ok), &host), Ok(()), "{ok}");
+    }
+    let newer = check_api(&v("1.4.0"), &host).unwrap_err();
+    assert!(newer.contains("1.4") && newer.contains("update OpenIDEA"), "{newer}");
+    assert!(check_api(&v("2.0.0"), &host).unwrap_err().contains("update OpenIDEA"));
+    let older = check_api(&v("0.2.0"), &host).unwrap_err();
+    assert!(older.contains("rebuild it with the 1.3 SDK"), "{older}");
+    // 0.x: every minor is its own API.
+    assert_eq!(check_api(&v("0.2.0"), &v("0.2.5")), Ok(()));
+    assert!(check_api(&v("0.1.0"), &v("0.2.0")).is_err());
+    assert!(check_api(&v("0.3.0"), &v("0.2.0")).is_err());
+}
+
+#[test]
+fn a_components_api_is_the_highest_plugin_interface_version() {
+    let names = ["wasi:io/[email protected]", "openidea:plugin/[email protected]", "openidea:plugin/[email protected]"];
+    assert_eq!(component_api(names), Ok(Some(v("1.2.0"))));
+    assert_eq!(component_api(["wasi:cli/[email protected]"]), Ok(None));
+    assert!(component_api(["openidea:plugin/log"]).unwrap_err().contains("unversioned"));
+}
+
+#[test]
+fn shipped_components_are_built_for_this_api() {
+    let engine = PluginEngine::new().unwrap();
+    let host = host_api();
+    for wasm in components() {
+        let component = engine.compile(&wasm).unwrap();
+        let built_for = engine.check_component(&component).unwrap_or_else(|e| panic!("{}: {e}", wasm.display()));
+        let built_for = built_for.unwrap_or_else(|| panic!("{} uses no plugin interface", wasm.display()));
+        assert_eq!((built_for.major, built_for.minor), (host.major, host.minor), "{}", wasm.display());
+    }
+}
+
+// --- a later host, simulated -------------------------------------------------------------
+
+struct Data {
+    wasi: WasiCtx,
+    table: ResourceTable,
+}
+
+impl WasiView for Data {
+    fn ctx(&mut self) -> WasiCtxView<'_> {
+        WasiCtxView { ctx: &mut self.wasi, table: &mut self.table }
+    }
+}
+
+/// Distinct host types for the stubbed resources (a component may import several).
+struct Stub<const N: usize>;
+
+fn stub_resource(n: usize) -> ResourceType {
+    macro_rules! pick { ($($i:literal)*) => { match n { $($i => ResourceType::host::<Stub<$i>>(),)* _ => panic!("more than 16 resources") } } }
+    pick!(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15)
+}
+
+enum Host<'a> {
+    /// Defines everything the component imports, plus a function and an
+    /// interface the component doesn't know.
+    Superset,
+    /// Leaves out one function, so linking must fail.
+    Without(&'a str),
+}
+
+/// A linker with WASI and every `openidea:plugin/*` interface `component`
+/// imports, defined at `version` with functions that are never called.
+fn host_at(engine: &Engine, component: &Component, version: &str, host: Host<'_>) -> Linker<Data> {
+    let mut linker = Linker::new(engine);
+    wasmtime_wasi::p2::add_to_linker_sync(&mut linker).unwrap();
+    // The component's resource → its stub. A resource re-exported through
+    // `use` (`invocation` uses `editor.text-editor`) is the same type, so it
+    // must get the same stub.
+    let mut resources: Vec<(ResourceType, ResourceType)> = Vec::new();
+    for (name, item) in component.component_type().imports(engine) {
+        let Some(rest) = name.strip_prefix("openidea:plugin/") else { continue };
+        let iface = rest.split_once('@').map_or(rest, |(i, _)| i);
+        let ComponentItem::ComponentInstance(instance) = item.ty else { panic!("{name} is not an instance") };
+        let mut defined = linker.instance(&format!("openidea:plugin/{iface}@{version}")).unwrap();
+        for (export, item) in instance.exports(engine) {
+            match item.ty {
+                ComponentItem::ComponentFunc(_) if !matches!(host, Host::Without(f) if f == export) => {
+                    defined.func_new(export, |_, _, _, _| Err(wasmtime::Error::msg("stub"))).unwrap();
+                }
+                ComponentItem::Resource(ty) => {
+                    let stub = match resources.iter().find(|(r, _)| *r == ty) {
+                        Some((_, stub)) => *stub,
+                        None => {
+                            let stub = stub_resource(resources.len());
+                            resources.push((ty, stub));
+                            stub
+                        }
+                    };
+                    defined.resource(export, stub, |_, _| Ok(())).unwrap();
+                }
+                _ => {}
+            }
+        }
+        if matches!(host, Host::Superset) {
+            defined.func_new("added-in-a-later-minor", |_, _, _, _| Ok(())).unwrap();
+        }
+    }
+    if matches!(host, Host::Superset) {
+        let mut added = linker.instance(&format!("openidea:plugin/added-interface@{version}")).unwrap();
+        added.func_new("call", |_, _, _, _| Ok(())).unwrap();
+    }
+    linker
+}
+
+fn engine() -> Engine {
+    let mut config = Config::new();
+    config.wasm_component_model(true);
+    Engine::new(&config).unwrap()
+}
+
+/// The next minor of the API this host implements.
+fn next_minor() -> String {
+    let host = host_api();
+    format!("{}.{}.0", host.major, host.minor + 1)
+}
+
+#[test]
+fn components_link_against_a_later_minor_that_adds_functions_and_interfaces() {
+    let engine = engine();
+    let next = next_minor();
+    for wasm in components() {
+        let component = Component::from_file(&engine, &wasm).unwrap();
+        let linker = host_at(&engine, &component, &next, Host::Superset);
+        linker.instantiate_pre(&component).unwrap_or_else(|e| panic!("{}: {e:?}", wasm.display()));
+
+        let exports: Vec<String> = component
+            .component_type()
+            .exports(&engine)
+            .map(|(n, _)| n.to_owned())
+            .filter(|n| n.starts_with("openidea:plugin/"))
+            .collect();
+        assert!(!exports.is_empty(), "{} exports no plugin interface", wasm.display());
+        for name in exports {
+            let iface = name.split_once('@').unwrap().0;
+            let newer = format!("{iface}@{next}");
+            assert!(
+                component.get_export_index(None, &newer).is_some(),
+                "{}: a {next} host can't find export {name}",
+                wasm.display()
+            );
+        }
+    }
+}
+
+#[test]
+fn components_do_not_link_against_another_major() {
+    let engine = engine();
+    let next_major = format!("{}.0.0", host_api().major + 1);
+    let wasm = repo().join("crates/ide-plugin/tests/fixtures/hello/dist/plugin.wasm");
+    let component = Component::from_file(&engine, &wasm).unwrap();
+    let linker = host_at(&engine, &component, &next_major, Host::Superset);
+    assert!(linker.instantiate_pre(&component).is_err());
+    let iface = component
+        .component_type()
+        .exports(&engine)
+        .map(|(n, _)| n.to_owned())
+        .find(|n| n.starts_with("openidea:plugin/"))
+        .unwrap();
+    let newer = format!("{}@{next_major}", iface.split_once('@').unwrap().0);
+    assert!(component.get_export_index(None, &newer).is_none());
+}
+
+#[test]
+fn a_later_minor_that_drops_a_function_does_not_link() {
+    // Keeps the test above honest: the stub host really is type-checked.
+    let engine = engine();
+    let wasm = repo().join("crates/ide-plugin/tests/fixtures/hello/dist/plugin.wasm");
+    let component = Component::from_file(&engine, &wasm).unwrap();
+    let (iface, func) = component
+        .component_type()
+        .imports(&engine)
+        .filter(|(n, _)| n.starts_with("openidea:plugin/"))
+        .find_map(|(n, item)| match item.ty {
+            ComponentItem::ComponentInstance(i) => i
+                .exports(&engine)
+                .find(|(_, it)| matches!(it.ty, ComponentItem::ComponentFunc(_)))
+                .map(|(f, _)| (n.to_owned(), f.to_owned())),
+            _ => None,
+        })
+        .expect("hello imports a plugin function");
+    let linker = host_at(&engine, &component, &next_minor(), Host::Without(&func));
+    let err = linker.instantiate_pre(&component).err().unwrap_or_else(|| panic!("{iface} without {func} linked"));
+    assert!(format!("{err:?}").contains(&func), "{err:?}");
+}

crates/ide-plugin/tests/fixtures/hello/Cargo.lock

@@ -95,12 +95,19 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98"
 
 [[package]]
-name = "openidea-plugin-hello"
+name = "openidea-plugin"
 version = "0.1.0"
 dependencies = [
  "wit-bindgen",
 ]
 
+[[package]]
+name = "openidea-plugin-hello"
+version = "0.1.0"
+dependencies = [
+ "openidea-plugin",
+]
+
 [[package]]
 name = "prettyplease"
 version = "0.3.0"

crates/ide-plugin/tests/fixtures/hello/Cargo.toml

@@ -8,10 +8,10 @@ publish = false
 [workspace]
 
 [lib]
-crate-type = ["cdylib"]
+crate-type = ["cdylib", "rlib"]
 
 [dependencies]
-wit-bindgen = "0.63"
+openidea-plugin = { path = "../../../../../sdk/rust/openidea-plugin" }
 
 [profile.release]
 opt-level = "s"

crates/ide-plugin/tests/fixtures/hello/dist/plugin.wasm.sources

@@ -0,0 +1 @@
+86dfe70a30ab1f7955a16e96c1b32c8be663456b871cc4d3bed7dc6052c062da

crates/ide-plugin/tests/fixtures/hello/plugin.toml

@@ -0,0 +1,52 @@
+id = "hello"
+name = "Hello"
+version = "0.3.0"
+description = "Sample plugin: inserts today's date, counts words in the active file and shows a tool window with a tree."
+authors = ["OpenIDEA contributors"]
+change-notes = """
+0.3.0 — a Greetings tool window (tree view), an editor context menu entry, a shortcut and a status bar item.
+0.2.0 — plugin API 0.2: edits are versioned, one undo step for every cursor.
+0.1.0 — first release: Insert Date and Word Count of Active File commands.
+"""
+engines.openidea = "^1.0"
+wasm = "dist/plugin.wasm"
+# Loaded the first time one of its commands runs.
+activation = ["on-command:*", "on-view:greetings"]
+
+[capabilities]
+required = ["editor.read", "editor.write"]
+
+# Static declarations make the commands visible before the plugin activates;
+# a command must be declared here to exist.
+[[contributes.commands]]
+id = "insert-date"
+title = "Hello: Insert Date"
+category = "Hello"
+
+[[contributes.commands]]
+id = "word-count"
+title = "Hello: Word Count of Active File"
+category = "Hello"
+
+# Declarative UI: shown without loading the plugin's code.
+[[contributes.menus]]
+menu = "editor.context"
+command = "word-count"
+
+[[contributes.keymaps]]
+command = "insert-date"
+key = "Ctrl+Alt+D"
+mac = "Meta+Alt+D"
+
+[[contributes.statusBar]]
+id = "hello"
+text = "Hello"
+tooltip = "Word count of the active file"
+command = "word-count"
+
+# A tool window whose tree the plugin renders (view-provider).
+[[contributes.views]]
+id = "greetings"
+title = "Greetings"
+icon = "plugin"
+location = "right"

crates/ide-plugin/tests/fixtures/hello/src/lib.rs

@@ -0,0 +1,180 @@
+//! Sample OpenIDEA plugin, written with the `openidea-plugin` SDK.
+//! Build with `openidea-plugin build plugins/hello` (see plugins/README.md).
+
+use openidea_plugin::views::{Body, Button, TreeItem, View, ViewEvent, Viewport, Views};
+use openidea_plugin::{Context, Error, Invocation, LogLevel, NotificationLevel, Plugin, host, register_plugin};
+use std::collections::BTreeSet;
+
+#[derive(Default)]
+struct Hello {
+    /// Expanded languages of the Greetings tree.
+    expanded: BTreeSet<String>,
+}
+
+/// The Greetings tree: languages, then their greetings (loaded when expanded).
+const GREETINGS: &[(&str, &[&str])] = &[
+    ("English", &["Hello", "Good morning", "Hi"]),
+    ("Deutsch", &["Hallo", "Guten Morgen", "Servus"]),
+    ("日本語", &["こんにちは", "おはよう"]),
+];
+
+impl Plugin for Hello {
+    fn activate(&mut self, ctx: &Context) -> Result<(), Error> {
+        host::log(LogLevel::Info, &format!("hello {} activated", ctx.plugin_version));
+        Ok(())
+    }
+
+    fn deactivate(&mut self) {
+        host::log(LogLevel::Info, "hello deactivated");
+    }
+
+    fn run_command(&mut self, id: &str, ctx: &Invocation, _arg: Option<&str>) -> Result<Option<String>, Error> {
+        let editor = ctx.editor().ok_or("no file is open in the editor")?;
+        match id {
+            "insert-date" => {
+                // Replaces every selection (inserts at every cursor), as one undo step.
+                let date = today();
+                editor.transform_selections(|_| date.clone())?;
+                Ok(Some(date))
+            }
+            "word-count" => {
+                let text = editor.document()?.text;
+                let path = editor.path();
+                let words = text.split_whitespace().count();
+                let lines = text.lines().count();
+                let name = path.rsplit(['/', '\\']).next().unwrap_or(&path);
+                let body = format!("{words} words, {lines} lines, {} characters", text.chars().count());
+                host::notify(NotificationLevel::Info, &format!("Word count: {name}"), &body);
+                Ok(Some(body))
+            }
+            other => Err(Error::NotFound(format!("command {other}"))),
+        }
+    }
+}
+
+impl Views for Hello {
+    fn render(&mut self, view: &str, _viewport: Option<Viewport>, _ctx: &Invocation) -> Result<View, Error> {
+        if view != "greetings" {
+            return Err(Error::NotFound(view.into()));
+        }
+        let mut items = Vec::new();
+        for (language, words) in GREETINGS {
+            let open = self.expanded.contains(*language);
+            items.push(
+                TreeItem::new(language, language).icon("folder").detail(&words.len().to_string()).expandable(open),
+            );
+            if open {
+                for w in *words {
+                    items.push(TreeItem::new(&format!("{language}/{w}"), w).parent(language).icon("text"));
+                }
+            }
+        }
+        Ok(View::new(Body::Tree(items))
+            .button(Button::new("collapse", "Collapse All").icon("collapse-all").enabled(!self.expanded.is_empty()))
+            .status(&format!("{} languages", GREETINGS.len())))
+    }
+
+    fn handle(&mut self, view: &str, event: ViewEvent, _ctx: &Invocation) -> Result<(), Error> {
+        match event {
+            ViewEvent::Expand(key) => {
+                self.expanded.insert(key);
+            }
+            ViewEvent::Collapse(key) => {
+                self.expanded.remove(&key);
+            }
+            ViewEvent::Button(b) if b == "collapse" => self.expanded.clear(),
+            ViewEvent::Activate(key) => {
+                if let Some((language, word)) = key.split_once('/') {
+                    host::notify(NotificationLevel::Info, word, &format!("A greeting in {language}"));
+                }
+                return Ok(());
+            }
+            _ => return Ok(()),
+        }
+        host::refresh_view(view);
+        Ok(())
+    }
+}
+
+register_plugin!(Hello, views);
+
+/// Today's UTC date as `YYYY-MM-DD` (WASI wall clock).
+fn today() -> String {
+    let secs =
+        std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).map(|d| d.as_secs() as i64).unwrap_or(0);
+    let (y, m, d) = civil_from_days(secs.div_euclid(86_400));
+    format!("{y:04}-{m:02}-{d:02}")
+}
+
+/// Howard Hinnant's days-to-civil algorithm.
+fn civil_from_days(z: i64) -> (i64, u32, u32) {
+    let z = z + 719_468;
+    let era = z.div_euclid(146_097);
+    let doe = z.rem_euclid(146_097);
+    let yoe = (doe - doe / 1460 + doe / 36_524 - doe / 146_096) / 365;
+    let doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
+    let mp = (5 * doy + 2) / 153;
+    let d = (doy - (153 * mp + 2) / 5 + 1) as u32;
+    let m = if mp < 10 { mp + 3 } else { mp - 9 } as u32;
+    let y = yoe + era * 400 + i64::from(m <= 2);
+    (y, m, d)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use openidea_plugin::mock::MockHost;
+
+    #[test]
+    fn civil_dates() {
+        assert_eq!(civil_from_days(0), (1970, 1, 1));
+        assert_eq!(civil_from_days(19_782), (2024, 2, 29));
+    }
+
+    #[test]
+    fn word_count_reads_the_focused_editor() {
+        let host = MockHost::install();
+        host.open_editor("/project/notes.txt", "text", "one two\nthree\n", &[]);
+        let out = Hello::default().run_command("word-count", &host.invocation(), None).unwrap();
+        assert_eq!(out.as_deref(), Some("3 words, 2 lines, 14 characters"));
+        assert_eq!(host.notifications()[0].title, "Word count: notes.txt");
+    }
+
+    #[test]
+    fn insert_date_replaces_every_selection_at_once() {
+        let host = MockHost::install();
+        host.open_editor("/project/a.txt", "text", "a\nXX b", &[(0, 1, 0, 1), (1, 0, 1, 2)]);
+        let date = Hello::default().run_command("insert-date", &host.invocation(), None).unwrap().unwrap();
+        assert_eq!(host.editor_text(), format!("a{date}\n{date} b"));
+        assert_eq!(host.editor_version(), 2, "one change");
+    }
+
+    #[test]
+    fn the_greetings_tree_loads_children_when_expanded() {
+        let host = MockHost::install();
+        let mut p = Hello::default();
+        let tree = |p: &mut Hello| match p.render("greetings", None, &host.invocation()).unwrap().body {
+            Body::Tree(items) => items,
+            other => panic!("{other:?}"),
+        };
+        assert_eq!(tree(&mut p).len(), 3);
+        p.handle("greetings", ViewEvent::Expand("Deutsch".into()), &host.invocation()).unwrap();
+        let items = tree(&mut p);
+        assert_eq!(items.len(), 6);
+        assert_eq!((items[2].label.as_str(), items[2].parent.as_deref()), ("Hallo", Some("Deutsch")));
+        assert_eq!(host.refreshed_views(), ["greetings"]);
+        p.handle("greetings", ViewEvent::Activate("Deutsch/Servus".into()), &host.invocation()).unwrap();
+        assert_eq!(host.notifications()[0].title, "Servus");
+        p.handle("greetings", ViewEvent::Button("collapse".into()), &host.invocation()).unwrap();
+        assert_eq!(tree(&mut p).len(), 3);
+    }
+
+    #[test]
+    fn without_editor_write_the_command_fails_cleanly() {
+        let host = MockHost::install().with_capabilities(&["editor.read"]);
+        host.open_editor("/project/a.txt", "text", "", &[(0, 0, 0, 0)]);
+        let err = Hello::default().run_command("insert-date", &host.invocation(), None).unwrap_err();
+        assert_eq!(err, Error::Denied("editor.write".into()));
+        assert_eq!(host.editor_text(), "");
+    }
+}