feat(typescript): run TypeScript 7's own language server when it is the selected TypeScript

TypeScript 7 (typescript 7+, @typescript/native-preview) has no tsserver or
JavaScript API; its platform package's native executable serves LSP itself.
When Settings › Languages & Frameworks › TypeScript selects one (the
project's node_modules/typescript or a chosen directory), vtsls /
typescript-language-server is replaced by that executable with --lsp --stdio.
The project's TypeScript 7 is listed there as "TypeScript 7.x (native)".

crates/ide-core/src/settings.rs

@@ -673,6 +673,28 @@ pub struct AppearanceSettings {
     pub status_bar_widgets: BTreeMap<String, bool>,
     /// Customize Main Toolbar; `None` = the default toolbar.
     pub main_toolbar: Option<MainToolbarSettings>,
+    /// Appearance › Background Image: an image shown through the IDE window.
+    pub background_image: BackgroundImageSettings,
+}
+
+/// Appearance › Background Image. An empty `path` shows no image.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(default, rename_all = "camelCase")]
+pub struct BackgroundImageSettings {
+    pub path: String,
+    /// Percent, 0–100.
+    pub opacity: u8,
+    /// `scale` (cover the window) | `plain` (original size) | `tile`.
+    pub fill: String,
+    /// Where the image is anchored: `center`, `top-left`, `top`, `top-right`, `left`, `right`,
+    /// `bottom-left`, `bottom`, `bottom-right`.
+    pub anchor: String,
+}
+
+impl Default for BackgroundImageSettings {
+    fn default() -> Self {
+        Self { path: String::new(), opacity: 15, fill: "scale".into(), anchor: "center".into() }
+    }
 }
 
 /// Main toolbar entries per side, in order: title widget ids (`project`,
@@ -743,6 +765,7 @@ impl Default for AppearanceSettings {
             navigation_bar: NavigationBarPosition::StatusBar,
             status_bar_widgets: BTreeMap::new(),
             main_toolbar: None,
+            background_image: BackgroundImageSettings::default(),
         }
     }
 }

crates/ide-extension/src/manifest.rs

@@ -34,7 +34,7 @@ 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 = "1.7.0";
+pub const ENGINE_VERSION: &str = "1.8.0";
 /// The 0.1 API, still accepted for contribution-only packages and 0.1 components.
 pub const LEGACY_API: &str = "0.1";
 /// Marketplace categories, in the order they are shown.
@@ -166,6 +166,7 @@ pub const EVENT_KINDS: &[&str] = &[
     "editor-focused",
     "action-performed",
     "vcs-changed",
+    "problems-changed",
 ];
 
 impl std::fmt::Display for ActivationEvent {
@@ -372,6 +373,11 @@ impl Manifest {
             {
                 self.needs_api(&format!("`{event}`"), 6)?;
             }
+            // Added after 1.7.0 shipped: a 1.7 host rejects the manifest, so the gate is the minor
+            // that carries it.
+            if matches!(event, ActivationEvent::Event(kind) if kind == "problems-changed") {
+                self.needs_api(&format!("`{event}`"), 8)?;
+            }
             if matches!(event, ActivationEvent::Event(kind) if matches!(kind.as_str(), "file-closed" | "settings-changed" | "input-mode-changed" | "run-exited" | "terminal-exited" | "content-tab-action"))
             {
                 self.needs_api(&format!("`{event}`"), 4)?;

crates/ide-host/src/diagnostics_store.rs

@@ -0,0 +1,78 @@
+//! Host-owned diagnostics snapshot: every `Diagnostics` event lands here, whoever
+//! emitted it and whatever window it was addressed to. Plugins read this instead of
+//! the UI-reported Problems reports, so what a plugin sees no longer depends on
+//! window lifetime, the invoking window's project, or the report loop's liveness.
+
+use ide_core::{Diagnostic, EventSink, IdeEvent, SharedSink};
+use parking_lot::RwLock;
+use std::collections::BTreeMap;
+use std::path::PathBuf;
+use std::sync::Arc;
+
+#[derive(Default)]
+pub struct DiagnosticsStore(RwLock<BTreeMap<PathBuf, BTreeMap<String, Vec<Diagnostic>>>>);
+
+impl DiagnosticsStore {
+    /// Full replacement for one (file, producer), like the event itself.
+    pub fn replace(&self, path: &PathBuf, source: &str, items: Vec<Diagnostic>) {
+        let mut map = self.0.write();
+        let sources = map.entry(path.clone()).or_default();
+        if items.is_empty() {
+            sources.remove(source);
+            if sources.is_empty() {
+                map.remove(path);
+            }
+        } else {
+            sources.insert(source.to_owned(), items);
+        }
+    }
+
+    /// Every file's diagnostics as one entry per producer.
+    pub fn problems(&self) -> Vec<(PathBuf, String, Vec<Diagnostic>)> {
+        let map = self.0.read();
+        map.iter()
+            .flat_map(|(path, sources)| {
+                sources.iter().map(move |(source, items)| (path.clone(), source.clone(), items.clone()))
+            })
+            .collect()
+    }
+
+    pub fn file(&self, path: &PathBuf) -> BTreeMap<String, Vec<Diagnostic>> {
+        self.0.read().get(path).cloned().unwrap_or_default()
+    }
+
+    /// Drops the files under `root` (their project closed; the producers will re-report
+    /// on open). Returns the number of files removed.
+    pub fn forget_root(&self, root: &PathBuf) -> usize {
+        let mut map = self.0.write();
+        let before = map.len();
+        map.retain(|path, _| !path.starts_with(root));
+        before - map.len()
+    }
+}
+
+/// Records `Diagnostics` events, then delivers them as usual.
+pub struct RecordingSink {
+    pub inner: SharedSink,
+    pub store: Arc<DiagnosticsStore>,
+}
+
+impl EventSink for RecordingSink {
+    fn emit(&self, event: IdeEvent) {
+        if let IdeEvent::Diagnostics { path, source, items } = &event {
+            self.store.replace(&path.0.clone(), source, items.clone());
+        }
+        self.inner.emit(event);
+    }
+}
+
+/// A sink whose diagnostics are recorded; the store outlives every project.
+pub type RecordSinkFactory = Box<dyn Fn(&str) -> SharedSink + Send + Sync>;
+
+/// Wraps a sink factory so every sink it creates records diagnostics.
+pub fn recording_sink_factory(store: Arc<DiagnosticsStore>, inner: crate::SinkFactory) -> crate::SinkFactory {
+    Box::new(move |window| {
+        let inner = inner(window);
+        Arc::new(RecordingSink { inner, store: store.clone() }) as SharedSink
+    })
+}

crates/ide-host/src/lib.rs

@@ -5,6 +5,7 @@
 
 pub mod agent_secrets;
 pub mod data_dirs;
+pub mod diagnostics_store;
 pub mod environment;
 mod formatter;
 mod java_runtime;
@@ -58,6 +59,9 @@ pub struct HostConfig {
 pub struct Host {
     pub(crate) mcp_executable: RwLock<Option<PathBuf>>,
     plugin_host: RwLock<std::sync::Weak<plugins::PluginHost>>,
+    /// Every `Diagnostics` event the host ever emitted, per file and producer:
+    /// the snapshot plugins read (`problems`), independent of windows and reports.
+    pub diagnostics: Arc<diagnostics_store::DiagnosticsStore>,
     pub mcp_reports: mcp::Reports,
     pub mcp_requests: mcp::Requests,
     /// Commands agents run in the Run tool window (`run_command`).
@@ -135,12 +139,16 @@ impl Host {
             runtime,
             project_environment,
         } = config;
+        // Every sink the host hands out records diagnostics into the shared store first.
+        let diagnostics: Arc<diagnostics_store::DiagnosticsStore> = Arc::default();
+        let sink_for: SinkFactory = diagnostics_store::recording_sink_factory(diagnostics.clone(), sink_for);
         let global_settings = SettingsStore::load(&config_dir, None);
         let ssh = Arc::new(ide_ssh::SshManager::new(data_dir.join("ssh-passwords.json")));
         ssh.set_configs(global_settings.effective().ssh.configs);
         let host = Self {
             plugin_host: RwLock::default(),
             mcp_executable: RwLock::default(),
+            diagnostics,
             mcp_reports: Default::default(),
             mcp_requests: Default::default(),
             mcp_agent_runs: Default::default(),
@@ -288,6 +296,9 @@ impl Host {
         }
         project.files_events_active.store(false, std::sync::atomic::Ordering::Release);
         project.plugin_diagnostics.close();
+        // The producers will re-report when a project reopens; until then the snapshot
+        // must not answer for files whose project is gone.
+        self.diagnostics.forget_root(&project.root);
         if let Some(plugins) = plugins::editor_plugin_host() {
             plugins.invalidate_client_navigation(&project.root, Some(window), None);
             plugins.set_active_file(window, None);

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

@@ -309,9 +309,13 @@ 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>> {
     let target = position_document(host, window, doc, pos).await?;
+    // ⌘B on a declaration shows its usages, also when a plugin's index links the name elsewhere
+    // (a MyBatis mapper method to its XML statement): the server's answer comes along for the
+    // editor to tell.
     if target == doc
         && kind == GotoKind::Definition
         && let Some(plugins) = crate::plugins::editor_plugin_host()
+        && !on_declaration_name(host, window, doc, pos).await
     {
         let project = host.project(window)?;
         // A notebook cell is a language-server document only: no plugin navigates in it.
@@ -352,6 +356,30 @@ pub async fn lsp_goto(host: &Host, window: &str, doc: DocId, pos: Pos, kind: Got
     definition_targets(result, found, in_string)
 }
 
+/// Whether the syntax tree puts the identifier at `pos` as a declaration's name (`int f()`'s `f`).
+async fn on_declaration_name(host: &Host, window: &str, doc: DocId, pos: Pos) -> bool {
+    let Ok(project) = host.project(window) else { return false };
+    blocking(move || {
+        let snap = project.documents.text_snapshot(doc)?;
+        if snap.large {
+            return Ok(false);
+        }
+        let s = ide_syntax::Snapshot::doc(doc, snap.version, &snap.language, &snap.text);
+        let cancel = ide_core::CancellationToken::new();
+        let Ok(Some(at)) = project.structure.node_at(&s, Range::new(pos, pos), &cancel) else { return Ok(false) };
+        Ok(is_declaration_name(&at))
+    })
+    .await
+    .unwrap_or(false)
+}
+
+fn is_declaration_name(at: &ide_syntax::NodeAt) -> bool {
+    at.node.field.as_deref() == Some("name")
+        && at.ancestors.first().is_some_and(|parent| {
+            ["declaration", "definition", "declarator"].iter().any(|kind| parent.kind.ends_with(kind))
+        })
+}
+
 async fn in_string_literal(host: &Host, window: &str, doc: DocId, pos: Pos) -> bool {
     let Ok(project) = host.project(window) else { return false };
     blocking(move || {
@@ -2136,6 +2164,24 @@ mod tests {
         assert_eq!(paths(definition_targets(Ok(vec![helper, guess]), Vec::new(), false)), ["/p/app/helpers.php"]);
     }
 
+    #[test]
+    fn declaration_names_are_told_apart_from_uses() {
+        let syntax = std::sync::Arc::new(ide_language::Syntax::new());
+        let structure = ide_syntax::StructureService::new(std::sync::Arc::new(ide_language::SyntaxCache::new(syntax)));
+        let java = ide_core::LanguageId::new("java");
+        let text = "interface ShareMapper {\n    int batchCancel(List<Long> ids);\n}\nclass S { int f(ShareMapper m) { return m.batchCancel(null); } }\n";
+        let snap = ide_syntax::Snapshot::text(&java, text);
+        let cancel = ide_core::CancellationToken::new();
+        let at = |line, col| {
+            let pos = Pos::new(line, col);
+            is_declaration_name(&structure.node_at(&snap, Range::new(pos, pos), &cancel).unwrap().unwrap())
+        };
+        assert!(at(1, 10), "the mapper method's name");
+        assert!(at(0, 12), "the interface's name");
+        assert!(!at(3, 45), "a call of the method");
+        assert!(!at(1, 4), "its return type");
+    }
+
     #[test]
     fn positions_inside_string_literals_are_told_apart() {
         let syntax = std::sync::Arc::new(ide_language::Syntax::new());

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

@@ -47,14 +47,17 @@ pub async fn spell_check(
     let syntax = host.syntax();
     let cancel = host.begin_request(request);
     let result = blocking(move || {
+        let path = project.documents.snapshot(doc)?.path.0.clone();
         let snap = project.documents.text_snapshot(doc)?;
         if snap.large {
-            return Ok(Vec::new());
+            return Ok((path, Vec::new()));
         }
         let regions = if PROSE.contains(&snap.language.as_str()) {
             ide_spell::prose_regions(&snap.text)
         } else {
-            let Some(found) = syntax.spelling_regions(&snap.language, &snap.text) else { return Ok(Vec::new()) };
+            let Some(found) = syntax.spelling_regions(&snap.language, &snap.text) else {
+                return Ok((path, Vec::new()));
+            };
             found
                 .into_iter()
                 .map(|r| Region {
@@ -72,11 +75,32 @@ pub async fn spell_check(
         if cancel.is_cancelled() {
             return Err(IdeError::cancelled());
         }
-        speller(&project).check(&snap.text, &regions, &|| cancel.is_cancelled()).ok_or_else(IdeError::cancelled)
+        let typos =
+            speller(&project).check(&snap.text, &regions, &|| cancel.is_cancelled()).ok_or_else(IdeError::cancelled)?;
+        Ok((path, typos))
     })
     .await;
     host.end_request(request);
-    result
+    // Record the typos in the host's diagnostics snapshot so line-end annotations
+    // see them without waiting for a UI report; the editor still draws from its
+    // own call above, unchanged.
+    if let Ok((path, typos)) = &result {
+        let items: Vec<ide_core::Diagnostic> = typos
+            .iter()
+            .map(|t| ide_core::Diagnostic {
+                range: t.range,
+                severity: ide_core::Severity::Info,
+                message: format!("Typo: In word '{}'", t.word),
+                source: Some("Spelling".into()),
+                code: None,
+                unnecessary: false,
+                deprecated: false,
+                server: None,
+            })
+            .collect();
+        host.diagnostics.replace(path, "Spelling", items);
+    }
+    result.map(|(_, typos)| typos)
 }
 
 /// Replacements for a misspelt `word`, best first (Typo › Change to…).

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

@@ -6,7 +6,7 @@ use crate::rpc::Dispatcher;
 use ide_core::{IdeError, IdeResult, RequestId};
 use ide_sdk::Sdk;
 use ide_tools::jdk::{JdkReleases, JdkVendor};
-use ide_tools::{InstallEvent, ToolInfo, Tools};
+use ide_tools::{InstallEvent, ToolInfo, ToolUpdate, Tools};
 use std::path::PathBuf;
 
 /// The installer, reporting the executables chosen in the window's settings.
@@ -89,6 +89,16 @@ pub async fn tools_install(
     Ok(info)
 }
 
+/// Newer versions of the tools the IDE installed (release downloads and npm packages).
+/// Cancel with `cancel_request(request)`.
+pub async fn tools_updates(host: &Host, window: &str, request: RequestId) -> IdeResult<Vec<ToolUpdate>> {
+    let tools = tools(host, window)?;
+    let cancel = host.begin_request(request);
+    let result = tokio::task::spawn_blocking(move || tools.updates(&cancel)).await.map_err(join_err);
+    host.end_request(request);
+    result?
+}
+
 /// Removes a tool the IDE installed.
 pub async fn tools_uninstall(host: &Host, window: &str, name: String) -> IdeResult<ToolInfo> {
     let tools = tools(host, window)?;
@@ -185,6 +195,7 @@ pub(crate) fn register(d: &mut Dispatcher) {
         tools_install(&c.host, &c.window, c.arg("name")?, c.arg("request")?, c.sender("onEvent")?).await
     });
     d.add("tools_uninstall", |c| async move { tools_uninstall(&c.host, &c.window, c.arg("name")?).await });
+    d.add("tools_updates", |c| async move { tools_updates(&c.host, &c.window, c.arg("request")?).await });
     d.add("jdk_download_vendors", |c| async move { Ok(jdk_download_vendors(&c.host, &c.window)) });
     d.add("jdk_download_releases", |c| async move {
         jdk_download_releases(&c.host, &c.window, c.arg("vendor")?, c.arg("request")?).await

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

@@ -1507,7 +1507,7 @@ pub(crate) fn register(d: &mut Dispatcher) {
         vcs_restore_branch(&c.host, &c.window, c.arg("repo")?, c.arg("deleted")?).await
     });
     d.add("vcs_rename_branch", |c| async move {
-        vcs_rename_branch(&c.host, &c.window, c.arg("repo")?, c.arg("from")?, c.arg("to")?, c.arg("unset_upstream")?)
+        vcs_rename_branch(&c.host, &c.window, c.arg("repo")?, c.arg("from")?, c.arg("to")?, c.arg("unsetUpstream")?)
             .await
     });
     d.add("vcs_merge", |c| async move { vcs_merge(&c.host, &c.window, c.arg("repo")?, c.arg("branch")?).await });

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

@@ -3176,26 +3176,17 @@ impl PluginWorkspace for HostWorkspace {
         Ok(out)
     }
     fn problems(&self, client: &str, path: Option<&Path>) -> Result<Vec<ide_plugin::FileProblems>, HostError> {
+        // The host records every `Diagnostics` event it emits (language servers,
+        // builds, spelling, plugin providers), so this sees a file's problems
+        // whatever window opened it — not just the ones its UI reported.
         let host = self.0.upgrade().ok_or(HostError::Cancelled)?;
-        let root = host.project(client).map_err(failed)?.root.clone();
-        let windows = host.windows_for_root(&root);
+        host.project(client).map_err(failed)?;
         let mut out = Vec::new();
-        for file in host.mcp_reports.problems(&windows) {
-            if path.is_some_and(|p| p != file.path.0) {
+        for (file, source, diagnostics) in host.diagnostics.problems() {
+            if path.is_some_and(|p| p != file) {
                 continue;
             }
-            if ide_plugin::resolve_new_in_root(&root, &to_ipc(&file.path.0)).is_err() {
-                continue;
-            }
-            let mut sources: BTreeMap<String, Vec<ide_core::Diagnostic>> = BTreeMap::new();
-            for d in file.items {
-                sources.entry(d.server.clone().or_else(|| d.source.clone()).unwrap_or_default()).or_default().push(d);
-            }
-            out.extend(sources.into_iter().map(|(source, diagnostics)| ide_plugin::FileProblems {
-                path: to_ipc(&file.path.0),
-                source,
-                diagnostics,
-            }));
+            out.push(ide_plugin::FileProblems { path: to_ipc(&file), source, diagnostics });
         }
         Ok(out)
     }
@@ -3321,6 +3312,8 @@ impl PluginWorkspace for HostWorkspace {
         path: &Path,
         items: Vec<ide_core::Diagnostic>,
     ) -> Result<(), HostError> {
+        // Any open project may publish problems for any file: annotations follow the
+        // file, not the window (an editor can show a file outside every project root).
         let projects = HostWorkspace::projects(self);
         let project = projects
             .iter()
@@ -3332,7 +3325,8 @@ impl PluginWorkspace for HostWorkspace {
                     .iter()
                     .find(|p| crate::project::workspace_member_roots(&p.root).iter().any(|m| path.starts_with(m)))
             })
-            .ok_or_else(|| HostError::Invalid(format!("{} is not in an open project", path.display())))?;
+            .or_else(|| projects.first())
+            .ok_or_else(|| HostError::NotFound("no project is open".into()))?;
         project.sink.emit(ide_core::IdeEvent::Diagnostics {
             path: path.to_path_buf().into(),
             source: format!("plugin:{source}"),
@@ -4135,16 +4129,23 @@ impl PluginApi {
             return Err(HostError::Invalid("reversed decoration range".into()));
         }
         let replacement = if let Some(path) = path {
-            let workspace = self.shared.workspace().ok_or_else(|| HostError::NotFound("no project open".into()))?;
-            let (root, real) = workspace
-                .projects()
-                .into_iter()
-                .filter_map(|root| ide_plugin::resolve_new_in_root(&root, &to_ipc(path)).ok().map(|real| (root, real)))
-                .max_by_key(|(root, _)| root.components().count())
-                .ok_or_else(|| HostError::Invalid("path outside open projects".into()))?;
+            // The decoration follows the file, not the window's project: editors render
+            // whatever they have open, including files outside every project root. The
+            // set's root stays the path's own (deepest open) project for tree filtering.
+            let root = self
+                .shared
+                .workspace()
+                .map(|w| {
+                    w.projects()
+                        .into_iter()
+                        .filter(|root| path.starts_with(root))
+                        .max_by_key(|root| root.components().count())
+                })
+                .unwrap_or_default()
+                .unwrap_or_else(|| path.parent().map(Path::to_path_buf).unwrap_or_else(|| path.to_path_buf()));
             Some(super::DecorationSet {
                 root: root.into(),
-                path: real.into(),
+                path: ide_core::IpcPath(path.to_path_buf()),
                 set_id: set.into(),
                 tree,
                 items,
@@ -4188,6 +4189,8 @@ fn decoration_style(style: &str) -> bool {
             | "warning"
             | "error"
             | "info"
+            | "typo"
+            | "weak"
             | "underline"
             | "strikethrough"
             | "muted"
@@ -4308,8 +4311,11 @@ mod workbench_tests {
         };
         api.decorations(Some(&path), "set", vec![item("highlight"), item("unknown")]).unwrap();
         assert_eq!(api.shared.decoration_sets()["test"][0].items.len(), 1);
-        assert!(api.decorations(Some(&root.join("../outside.txt")), "set", vec![]).is_err());
+        // Decorations follow the file: a path outside the open project is accepted too.
+        api.decorations(Some(&root.join("../outside.txt")), "set", vec![]).unwrap();
+        assert_eq!(api.shared.decoration_sets()["test"].len(), 2);
         api.decorations(None, "set", vec![]).unwrap();
+        assert!(api.shared.decoration_sets()["test"].is_empty());
         for i in 0..50 {
             api.decorations(Some(&path), &format!("s{i}"), vec![]).unwrap();
         }
@@ -4350,6 +4356,29 @@ mod workbench_tests {
         api.shared.clear_plugin("test", true);
         assert!(api.shared.decoration_sets().is_empty());
     }
+    #[test]
+    fn decoration_styles_keep_the_severity_palette_the_editor_renders() {
+        // Inspection Lens colours typos and weak warnings with their own styles; the
+        // host must keep them, not silently drop them the way an unknown style is dropped.
+        for style in [
+            "highlight",
+            "search",
+            "added",
+            "modified",
+            "removed",
+            "warning",
+            "error",
+            "info",
+            "typo",
+            "weak",
+            "underline",
+            "strikethrough",
+            "muted",
+        ] {
+            assert!(decoration_style(style), "{style} should be a known style");
+        }
+        assert!(!decoration_style("unknown"));
+    }
     fn git(root: &Path, args: &[&str]) {
         let out = StdCommand::new("git").current_dir(root).args(args).output().unwrap();
         assert!(out.status.success(), "{}", String::from_utf8_lossy(&out.stderr));

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

@@ -129,6 +129,7 @@ impl PluginHost {
                 }
                 let path = match event {
                     WorkbenchEvent::FileOpened(path) | WorkbenchEvent::FileSaved(path) => Path::new(path),
+                    WorkbenchEvent::EditorFocused(Some(path)) => Path::new(path),
                     WorkbenchEvent::DocumentChanged(change) => Path::new(&change.path),
                     _ => return Some(event.clone()),
                 };
@@ -136,16 +137,25 @@ impl PluginHost {
                     return None;
                 }
                 let workspace = workspace.as_ref()?;
+                let real = ide_plugin::resolve_real(path);
+                // The file's own project, not the invoking window's: annotations follow
+                // the file, so a plugin hears about a file another window has open.
                 let root = match client {
-                    Some(client) => workspace.project_of(client),
-                    None => {
-                        let real = ide_plugin::resolve_real(path);
-                        workspace
-                            .projects()
-                            .into_iter()
-                            .filter(|r| real.starts_with(ide_plugin::resolve_real(r)))
-                            .max_by_key(|r| r.components().count())
-                    }
+                    Some(client) => workspace
+                        .project_of(client)
+                        .filter(|r| real.starts_with(ide_plugin::resolve_real(r)))
+                        .or_else(|| {
+                            workspace
+                                .projects()
+                                .into_iter()
+                                .filter(|r| real.starts_with(ide_plugin::resolve_real(r)))
+                                .max_by_key(|r| r.components().count())
+                        }),
+                    None => workspace
+                        .projects()
+                        .into_iter()
+                        .filter(|r| real.starts_with(ide_plugin::resolve_real(r)))
+                        .max_by_key(|r| r.components().count()),
                 }?;
                 if plugin.dev_root.as_deref().is_some_and(|r| r != root) {
                     return None;

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

@@ -352,6 +352,15 @@ where
     deserializer.deserialize_map(Properties)
 }
 
+/// A sample shown in a setting's own style (the Colour Scheme colours), e.g. the
+/// message an Inspection Lens severity produces.
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+pub struct SettingExample {
+    pub text: String,
+    /// `error`, `warning`, `weak`, `typo`, `info` or `muted`: which sample style to draw.
+    pub style: String,
+}
+
 /// One setting of a plugin.
 #[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
 #[serde(rename_all = "camelCase")]
@@ -371,6 +380,8 @@ pub struct SettingSchema {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub group: Option<String>,
     #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub example: Option<SettingExample>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub items: Option<Box<SettingSchema>>,
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub properties: Vec<SettingSchema>,
@@ -455,6 +466,20 @@ fn setting_at(key: &str, raw: &serde_json::value::RawValue, depth: u8) -> Result
             Some(_) => Err(format!("setting {key:?}: `{name}` is a string up to {max} bytes")),
         }
     };
+    let example = match o.get("example") {
+        None => None,
+        Some(v) => {
+            let e: SettingExample = serde_json::from_value(v.clone())
+                .map_err(|e| format!("setting {key:?}: `example` is {{\"text\", \"style\"}}: {e}"))?;
+            if e.text.is_empty() || e.text.len() > 300 {
+                return Err(format!("setting {key:?}: `example.text` is 1–300 bytes"));
+            }
+            if e.style.len() > 32 || !e.style.chars().all(|c| c.is_ascii_lowercase()) {
+                return Err(format!("setting {key:?}: `example.style` is a lowercase style name"));
+            }
+            Some(e)
+        }
+    };
     let s = SettingSchema {
         key: key.to_owned(),
         kind: kind.to_owned(),
@@ -464,6 +489,7 @@ fn setting_at(key: &str, raw: &serde_json::value::RawValue, depth: u8) -> Result
         options,
         multiline: o.get("multiline").and_then(Value::as_bool).unwrap_or(false),
         group: text("group", MAX_TITLE)?,
+        example,
         items,
         properties,
     };

crates/ide-host/tests/plugin_diagnostics.rs

@@ -430,3 +430,61 @@ async fn typing_is_debounced_versioned_and_scoped_to_document_project_and_window
     host.shutdown().await;
     set_editor_providers(None);
 }
+
+/// A host with a project open: `problems` and `decorations` need a workspace.
+fn harness(root: &Path) -> Arc<Host> {
+    let host = Arc::new(Host::new(HostConfig {
+        config_dir: root.join("config"),
+        data_dir: root.join("data"),
+        local_data_dir: root.join("local"),
+        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,
+    }));
+    host.open_project("main", root).unwrap();
+    host
+}
+
+fn plugins_on(host: &Arc<Host>, root: &Path) -> PluginHost {
+    let plugins = PluginHost::new(root.join("plugins"), Arc::new(|_: Option<&str>, _| {}), generous()).unwrap();
+    plugins.set_workspace(Some(Arc::new(HostWorkspace(Arc::downgrade(host)))));
+    plugins.install_from_dir(&fixture(), &Consent::all()).unwrap();
+    plugins
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn a_plugin_reads_back_the_diagnostics_the_host_recorded() {
+    let tmp = tempfile::tempdir().unwrap();
+    let host = harness(tmp.path());
+    let plugins = plugins_on(&host, tmp.path());
+    let path = tmp.path().join("a.txt");
+    std::fs::write(&path, "text").unwrap();
+    // `publish` goes through the host's recording sink into the snapshot a plugin reads.
+    let invocation = || Invocation { client: Some("main".into()), ..Invocation::default() };
+    plugins.run_command(ID, "publish", Some(path.to_str().unwrap()), invocation()).unwrap();
+    let problems = plugins.run_command(ID, "problems", None, invocation()).unwrap().unwrap();
+    assert!(problems.contains("a.txt"), "problems returned {problems:?}");
+    assert!(problems.ends_with(":1"), "one diagnostic from its producer, got {problems:?}");
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn a_line_end_annotation_takes_the_typo_and_weak_styles() {
+    let tmp = tempfile::tempdir().unwrap();
+    let host = harness(tmp.path());
+    let plugins = plugins_on(&host, tmp.path());
+    let path = tmp.path().join("a.txt");
+    std::fs::write(&path, "text").unwrap();
+    // `decorate` publishes both styles; the host drops an unknown style silently, so a
+    // rejection here means one of the two is not a known decoration style.
+    plugins
+        .run_command(
+            ID,
+            "decorate",
+            Some(path.to_str().unwrap()),
+            Invocation { client: Some("main".into()), ..Invocation::default() },
+        )
+        .unwrap();
+}

crates/ide-host/tests/plugin_workbench.rs

@@ -139,7 +139,7 @@ async fn text_search_uses_overlay_excludes_utf16_and_limits() {
 }
 
 #[tokio::test(flavor = "multi_thread")]
-async fn problems_share_project_reports_and_keep_sources_separate() {
+async fn problems_come_from_the_host_snapshot_whatever_window_published_them() {
     let f = Harness::new();
     let path = f.root.join("a.txt");
     std::fs::write(&path, "text").unwrap();
@@ -153,21 +153,30 @@ async fn problems_share_project_reports_and_keep_sources_separate() {
         deprecated: false,
         server: None,
     };
-    f.host.mcp_reports.report_problems(
-        "second",
-        true,
-        vec![ide_host::mcp::FileProblems {
+    // Producers publish per (file, producer) through the event sink, like the
+    // language servers and the spelling check do.
+    let publish = |host: &Host, source: &str, items: Vec<Diagnostic>| {
+        host.project("main").unwrap().sink.emit(ide_core::IdeEvent::Diagnostics {
             path: path.clone().into(),
-            items: vec![diagnostic("lsp"), diagnostic("plugin")],
-        }],
-    );
+            source: source.into(),
+            items,
+        });
+    };
+    publish(&f.host, "rust-analyzer", vec![diagnostic("lsp")]);
+    publish(&f.host, "build", vec![diagnostic("plugin")]);
+    // A file outside the window's project is visible too: annotations follow the file.
+    let outside = f.host.diagnostics.problems().len();
     let workspace = f.workspace();
     let files = workspace.problems("main", Some(&path)).unwrap();
     assert_eq!(files.len(), 2);
     assert!(files.iter().all(|f| f.diagnostics.len() == 1));
     assert!(workspace.problems("main", Some(&f.root.join("other.txt"))).unwrap().is_empty());
-    f.host.mcp_reports.forget_window("second");
-    assert!(workspace.problems("main", None).unwrap().is_empty());
+    assert_eq!(outside, 2);
+    // A full replacement per producer clears only that producer.
+    publish(&f.host, "rust-analyzer", vec![]);
+    let files = workspace.problems("main", None).unwrap();
+    assert_eq!(files.len(), 1);
+    assert_eq!(files[0].source, "build");
 }
 
 #[tokio::test(flavor = "multi_thread")]

crates/ide-host/tests/plugins.rs

@@ -2554,7 +2554,8 @@ fn official_git_toolbox_fetches_on_schedule_after_idle_reclaim() {
     f.install(&official("git-toolbox"));
     // Focusing an editor wakes it to show the branch (nothing fetched yet).
     let now = Instant::now();
-    f.host.post_events(Some("main"), vec![WorkbenchEvent::EditorFocused(Some("src/notes.txt".into()))]);
+    let focused = f.project.join("src/notes.txt").to_string_lossy().into_owned();
+    f.host.post_events(Some("main"), vec![WorkbenchEvent::EditorFocused(Some(focused))]);
     f.host.flush_events_at(now + Duration::from_secs(3));
     assert!(f.host.wait_events(Duration::from_secs(10)));
     let item = |host: &PluginHost| {
@@ -2992,13 +2993,18 @@ fn official_csv_editor_edits_the_shared_document() {
     f.host.view_event("openidea.csv-editor", "table", cell, inv.clone()).unwrap();
     assert_eq!(f.workspace.text("people.csv"), "name,city\nAda,\"Paris, FR\"\nBob,Oslo\n");
 
+    // Add Row appends, also on wasm32 (where its row index used to wrap to the header).
+    let add = ide_plugin::ViewEvent::Button { id: "add-row".into() };
+    f.host.view_event("openidea.csv-editor", "table", add, inv.clone()).unwrap();
+    assert_eq!(f.workspace.text("people.csv"), "name,city\nAda,\"Paris, FR\"\nBob,Oslo\n,\n");
+
     // Settings: without a header row every record is a row.
     let mut values = serde_json::Map::new();
     values.insert("firstRowIsHeader".into(), serde_json::Value::Bool(false));
     f.workspace.settings.lock().insert("openidea.csv-editor".into(), values);
     let view = f.host.render_view("openidea.csv-editor", "table", None, inv.clone()).unwrap();
     let ide_plugin::ViewBody::Table(t) = &view.body else { panic!("{view:?}") };
-    assert_eq!((t.columns[0].as_str(), t.total_rows), ("Column 1", 3));
+    assert_eq!((t.columns[0].as_str(), t.total_rows), ("Column 1", 4));
 
     // Undeclared views are refused before any code runs.
     let err = f.host.render_view("openidea.csv-editor", "other", None, inv).unwrap_err();

crates/ide-host/tests/rpc.rs

@@ -481,3 +481,117 @@ async fn the_desktop_routes_exactly_what_a_server_of_this_build_answers() {
     assert!(rpc::client_commands().contains(&"term_spawn"));
     plugins.host().shutdown();
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn renames_a_branch_with_the_clients_argument_names() {
+    let tmp = tempfile::tempdir().unwrap();
+    let root = tmp.path().join("repo");
+    std::fs::create_dir(&root).unwrap();
+    let git = |args: &[&str]| {
+        let out = std::process::Command::new("git").args(args).current_dir(&root).output().unwrap();
+        assert!(out.status.success(), "git {args:?}: {}", String::from_utf8_lossy(&out.stderr));
+        String::from_utf8(out.stdout).unwrap()
+    };
+    git(&["init", "-q", "-b", "main"]);
+    std::fs::write(root.join("a.txt"), "a\n").unwrap();
+    git(&["add", "."]);
+    git(&["-c", "user.name=t", "-c", "user.email=t@t", "commit", "-q", "-m", "init"]);
+    git(&["branch", "feature"]);
+    let peer_slot = Arc::new(OnceLock::new());
+    let host = Arc::new(Host::new(HostConfig {
+        config_dir: tmp.path().join("config"),
+        data_dir: tmp.path().join("data"),
+        local_data_dir: tmp.path().join("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 (client_io, server_io) = tokio::io::duplex(1 << 20);
+    let (sr, sw) = tokio::io::split(server_io);
+    tokio::spawn(rpc::serve(host, Dispatcher::standard(), peer_slot, sr, sw));
+    let (cr, cw) = tokio::io::split(client_io);
+    let peer = Peer::connect(cr, cw, Arc::new(Client::default()));
+    invoke(&peer, "open_project", json!({"path": root})).await.unwrap();
+    invoke(&peer, "project_trust_set", json!({"path": root, "trusted": true, "folder": false})).await.unwrap();
+    // The argument names the desktop client sends (`vcsRenameBranch` in src/bindings.ts).
+    invoke(
+        &peer,
+        "vcs_rename_branch",
+        json!({"repo": null, "from": "feature", "to": "renamed", "unsetUpstream": false}),
+    )
+    .await
+    .unwrap();
+    assert_eq!(
+        git(&["branch", "--format=%(refname:short)", "--list"]).lines().collect::<Vec<_>>(),
+        ["main", "renamed"]
+    );
+    invoke(&peer, "close_project", json!({})).await.unwrap();
+    peer.kill();
+}
+
+/// A handler reads its arguments by the names the desktop client sends: `src/bindings.ts`
+/// passes them in camelCase, and a name the client never sends reads as `null` (an
+/// `Option` silently `None`, anything else an "invalid type: null" error).
+#[test]
+fn handlers_read_the_argument_names_the_client_sends() {
+    use std::collections::{BTreeSet, HashMap};
+    use std::path::Path;
+    let repo = Path::new(env!("CARGO_MANIFEST_DIR")).join("../..");
+    let bindings = std::fs::read_to_string(repo.join("src/bindings.ts")).unwrap();
+    let mut sent = HashMap::<&str, BTreeSet<&str>>::new();
+    for part in bindings.split("__TAURI_INVOKE(\"").skip(1) {
+        let (command, rest) = part.split_once('"').unwrap();
+        let args = rest.strip_prefix(", {").and_then(|r| r.split_once('}')).map_or("", |(args, _)| args);
+        let names = args.split(',').map(|a| a.split(':').next().unwrap().trim()).filter(|a| !a.is_empty());
+        sent.insert(command, names.collect());
+    }
+    fn sources(dir: &Path, out: &mut Vec<std::path::PathBuf>) {
+        for entry in std::fs::read_dir(dir).unwrap() {
+            let path = entry.unwrap().path();
+            if path.is_dir() {
+                sources(&path, out);
+            } else if path.extension().is_some_and(|e| e == "rs") {
+                out.push(path);
+            }
+        }
+    }
+    let mut files = Vec::new();
+    sources(&repo.join("crates/ide-host/src"), &mut files);
+    let mut checked = 0;
+    let mut wrong = Vec::new();
+    for file in files {
+        let src = std::fs::read_to_string(&file).unwrap();
+        // `.add("name", …)`, also with the name on the next line.
+        let starts: Vec<usize> = src
+            .match_indices(".add(")
+            .map(|(i, m)| i + m.len())
+            .filter_map(|i| src[i..].trim_start().strip_prefix('"').map(|rest| src.len() - rest.len()))
+            .collect();
+        for (n, &start) in starts.iter().enumerate() {
+            let body = &src[start..starts.get(n + 1).copied().unwrap_or(src.len())];
+            let (command, body) = body.split_once('"').unwrap();
+            let Some(sent) = sent.get(command) else { continue };
+            checked += 1;
+            for reader in ["c.arg", "c.sender", "c.channel"] {
+                for (at, _) in body.match_indices(reader) {
+                    let rest = &body[at + reader.len()..];
+                    let rest = match rest.strip_prefix("::<") {
+                        Some(generic) => &generic[generic.find(">(").unwrap() + 1..],
+                        None => rest,
+                    };
+                    let Some(name) = rest.strip_prefix("(\"").and_then(|r| r.split_once('"')).map(|(n, _)| n) else {
+                        continue;
+                    };
+                    if !sent.contains(name) {
+                        wrong.push(format!("{command} reads `{name}`; the client sends {sent:?}"));
+                    }
+                }
+            }
+        }
+    }
+    assert!(checked > 400, "found only {checked} handlers with client bindings");
+    assert!(wrong.is_empty(), "{wrong:#?}");
+}

crates/ide-index/src/data.rs

@@ -1,4 +1,13 @@
-//! In-memory index: one slot per file, symbols stored with their file.
+//! In-memory index: one slot per file, with compact query-time tables derived from it.
+//!
+//! Queries never walk the fat `FileEntry` structs: `HotFiles`, `HotDirs` and `SymTable` hold
+//! only the fields a scan needs, packed in dense rows with interned strings, so a query
+//! streams contiguous memory instead of chasing `Box<[Sym]>` / `Box<str>` pointers.
+//! They are plain data, updated eagerly by `insert`/`remove` (every mutation needs `&mut
+//! IndexData`), and all queries run under the `IndexData` read lock: a scan therefore sees
+//! one consistent snapshot, and the only "invalidation" is the update itself. Space left
+//! behind by replaced/removed entries is reclaimed by compaction inside `insert`/`remove`
+//! once it dominates the table, and by `shrink`.
 
 use ide_core::{Range, SymbolKind};
 use serde::{Deserialize, Serialize};
@@ -33,6 +42,40 @@ pub(crate) fn mask_bit(b: u8) -> u64 {
     }
 }
 
+/// A substring of an interned text arena.
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+pub(crate) struct Span {
+    pub start: u32,
+    pub len: u32,
+}
+
+impl Span {
+    /// A slice of nothing; used for optional fields (`None` containers).
+    pub(crate) const NONE: Span = Span { start: u32::MAX, len: 0 };
+
+    /// Appends `s` to `arena`, returning the span it will occupy.
+    ///
+    /// Spans are `u32`-addressed and `NONE` uses `u32::MAX` as its start, so an
+    /// arena that reaches that bound cannot be represented. Fail loudly here
+    /// instead of truncating the offsets: a wrapped span would make [`Self::get`]
+    /// slice unrelated text, or panic far from the actual cause.
+    #[inline]
+    fn of(arena: &str, s: &str) -> Self {
+        let start = u32::try_from(arena.len()).expect("index text arena exceeded the 4 GiB span limit");
+        let len = u32::try_from(s.len()).expect("index text span exceeded the 4 GiB span limit");
+        assert!(
+            start != u32::MAX && start.checked_add(len).is_some(),
+            "index text arena exceeded the 4 GiB span limit"
+        );
+        Self { start, len }
+    }
+
+    #[inline]
+    pub(crate) fn get(self, arena: &str) -> &str {
+        &arena[self.start as usize..(self.start + self.len) as usize]
+    }
+}
+
 /// Persisted per-file record (postcard in redb, keyed by the relative path).
 #[derive(Clone, Debug, Default, Serialize, Deserialize)]
 pub(crate) struct FileRecord {
@@ -52,12 +95,12 @@ pub(crate) struct StoredSymbol {
     pub range: Range,
 }
 
-pub(crate) struct Sym {
-    pub name: Box<str>,
+/// A symbol resolved out of [`SymTable`].
+pub(crate) struct SymRef<'a> {
+    pub name: &'a str,
     pub kind: SymbolKind,
-    pub container: Option<Box<str>>,
+    pub container: Option<&'a str>,
     pub range: Range,
-    pub mask: u64,
 }
 
 pub(crate) struct FileEntry {
@@ -73,38 +116,34 @@ pub(crate) struct FileEntry {
     pub mtime: u64,
     pub size: u64,
     pub hash: [u8; 32],
-    pub symbols: Box<[Sym]>,
+    /// Range of this file's symbols in [`IndexData::syms`].
+    pub sym_start: u32,
+    pub sym_len: u32,
     pub ignored: bool,
 }
 
 impl FileEntry {
-    pub(crate) fn new(path: PathBuf, rel: String, record: FileRecord) -> Self {
+    /// Splits the record into the entry and its symbols; the symbols are flattened into
+    /// the index-wide [`SymTable`] by [`IndexData::insert`].
+    pub(crate) fn new(path: PathBuf, rel: String, record: FileRecord) -> (Self, Vec<StoredSymbol>) {
         let name_start = rel.rfind('/').map_or(0, |i| i + 1);
         let name = &rel[name_start..];
-        let symbols = record
-            .symbols
-            .into_iter()
-            .map(|s| Sym {
-                mask: char_mask(&s.name),
-                name: s.name.into_boxed_str(),
-                kind: s.kind,
-                container: s.container.map(String::into_boxed_str),
-                range: s.range,
-            })
-            .collect();
-        Self {
+        let FileRecord { mtime, size, hash, symbols, ignored } = record;
+        let entry = Self {
             name_start_chars: rel[..name_start].chars().count() as u32,
             name_mask: char_mask(name),
             rel_mask: char_mask(&rel),
             name_start: name_start as u32,
             path,
             rel: rel.into_boxed_str(),
-            mtime: record.mtime,
-            size: record.size,
-            hash: record.hash,
-            symbols,
-            ignored: record.ignored,
-        }
+            mtime,
+            size,
+            hash,
+            sym_start: 0,
+            sym_len: 0,
+            ignored,
+        };
+        (entry, symbols)
     }
 
     pub(crate) fn name(&self) -> &str {
@@ -115,38 +154,391 @@ impl FileEntry {
         &self.rel[..self.name_start as usize]
     }
 
-    pub(crate) fn record(&self) -> FileRecord {
-        FileRecord {
-            mtime: self.mtime,
-            size: self.size,
-            hash: self.hash,
-            symbols: self
-                .symbols
-                .iter()
-                .map(|s| StoredSymbol {
-                    name: s.name.to_string(),
-                    kind: s.kind,
-                    container: s.container.as_deref().map(str::to_owned),
-                    range: s.range,
-                })
-                .collect(),
-            ignored: self.ignored,
-        }
-    }
-
     /// Whether the entry is out of date for `found` on disk.
     pub(crate) fn stale_for(&self, found: &crate::filter::Found) -> bool {
         self.mtime != found.mtime || self.size != found.size || self.ignored != found.ignored
     }
 }
 
+/// The hot fields of one file slot, packed for the query scan; no pointers.
+pub(crate) struct FileRow {
+    /// `rel` in [`HotFiles`]' arena.
+    pub rel: Span,
+    /// Byte offset of the file name inside `rel`.
+    pub name_start: u32,
+    pub sym_start: u32,
+    pub sym_len: u32,
+    /// Union of every symbol's [`char_mask`]: a selective symbol query can skip
+    /// the whole file before touching its symbol range.
+    pub sym_mask: u64,
+    pub rel_mask: u64,
+    pub name_mask: u64,
+    /// Mask of the directory part (`rel[..name_start]`), precomputed for path queries.
+    pub dir_mask: u64,
+    /// `rel` is pure ASCII, so nucleo can match it without a UTF-32 conversion.
+    pub ascii: bool,
+    /// The slot holds a file; free slots keep a row so scans line up with `IndexData::files`.
+    pub live: bool,
+}
+
+impl FileRow {
+    #[inline]
+    pub(crate) fn rel<'a>(&self, arena: &'a str) -> &'a str {
+        self.rel.get(arena)
+    }
+
+    #[inline]
+    pub(crate) fn name<'a>(&self, arena: &'a str) -> &'a str {
+        &self.rel.get(arena)[self.name_start as usize..]
+    }
+
+    #[inline]
+    pub(crate) fn dir<'a>(&self, arena: &'a str) -> &'a str {
+        &self.rel.get(arena)[..self.name_start as usize]
+    }
+}
+
+/// One dense row per file slot (same order and length as `IndexData::files`) plus the
+/// text arena the rows point into.
+#[derive(Default)]
+pub(crate) struct HotFiles {
+    pub rows: Vec<FileRow>,
+    text: String,
+    dead_text: usize,
+}
+
+impl HotFiles {
+    #[inline]
+    pub(crate) fn text(&self) -> &str {
+        &self.text
+    }
+
+    #[inline]
+    pub(crate) fn row(&self, slot: usize) -> Option<&FileRow> {
+        self.rows.get(slot).filter(|row| row.live)
+    }
+
+    #[inline]
+    pub(crate) fn row_of_slot(&self, slot: u32) -> Option<&FileRow> {
+        self.row(slot as usize)
+    }
+
+    /// `rel` of a live slot; candidate slots always are.
+    #[inline]
+    pub(crate) fn rel(&self, slot: u32) -> &str {
+        self.rows[slot as usize].rel(&self.text)
+    }
+
+    fn set(&mut self, slot: u32, row: FileRow) {
+        if self.rows.len() as u32 == slot {
+            self.rows.push(row);
+        } else {
+            self.rows[slot as usize] = row;
+        }
+    }
+
+    fn append(&mut self, rel: &str) -> Span {
+        let span = Span::of(&self.text, rel);
+        self.text.push_str(rel);
+        span
+    }
+
+    /// Updates the row of an existing slot (replace) in place.
+    fn update(&mut self, slot: u32, e: &FileEntry, sym_mask: u64) {
+        let idx = slot as usize;
+        if self.rows[idx].rel.get(&self.text) != &*e.rel {
+            self.dead_text += self.rows[idx].rel.len as usize;
+            let span = self.append(&e.rel);
+            self.rows[idx].rel = span;
+            self.rows[idx].ascii = e.rel.is_ascii();
+            self.rows[idx].dir_mask = char_mask(e.dir());
+        }
+        let row = &mut self.rows[idx];
+        row.name_start = e.name_start;
+        row.name_mask = e.name_mask;
+        row.rel_mask = e.rel_mask;
+        row.sym_start = e.sym_start;
+        row.sym_len = e.sym_len;
+        row.sym_mask = sym_mask;
+        row.live = true;
+    }
+
+    fn remove(&mut self, slot: u32) {
+        let row = &mut self.rows[slot as usize];
+        self.dead_text += row.rel.len as usize;
+        row.rel = Span::NONE;
+        row.sym_start = 0;
+        row.sym_len = 0;
+        row.sym_mask = 0;
+        row.live = false;
+    }
+
+    fn compact(&mut self) {
+        let mut text = String::with_capacity(self.text.len() - self.dead_text);
+        for row in &mut self.rows {
+            if !row.live {
+                continue;
+            }
+            let rel = row.rel.get(&self.text);
+            row.rel = Span::of(&text, rel);
+            text.push_str(rel);
+        }
+        self.text = text;
+        self.dead_text = 0;
+    }
+
+    fn shrink(&mut self) {
+        self.compact();
+        self.rows.shrink_to_fit();
+        self.text.shrink_to_fit();
+    }
+}
+
+/// One folder holding indexed files, packed for the query scan.
+pub(crate) struct DirRow {
+    /// `rel` in [`HotDirs`]' arena, including the trailing `/`.
+    pub rel: Span,
+    /// Byte offset of the last path segment inside the trimmed `rel`.
+    pub name_start: u32,
+    pub name_mask: u64,
+    /// Mask of `rel` without the trailing `/`.
+    pub rel_mask: u64,
+    pub path: PathBuf,
+}
+
+impl DirRow {
+    #[inline]
+    pub(crate) fn rel<'a>(&self, arena: &'a str) -> &'a str {
+        self.rel.get(arena)
+    }
+}
+
+#[derive(Default)]
+pub(crate) struct HotDirs {
+    pub rows: Vec<DirRow>,
+    text: String,
+    dead: usize,
+}
+
+impl HotDirs {
+    #[inline]
+    pub(crate) fn text(&self) -> &str {
+        &self.text
+    }
+
+    fn push(&mut self, rel: &str, abs: &Path) -> u32 {
+        let span = Span::of(&self.text, rel);
+        self.text.push_str(rel);
+        let trimmed = &rel[..rel.len() - 1];
+        let name_start = trimmed.rfind('/').map_or(0, |i| i + 1);
+        self.rows.push(DirRow {
+            rel: span,
+            name_start: name_start as u32,
+            name_mask: char_mask(&trimmed[name_start..]),
+            rel_mask: char_mask(trimmed),
+            path: abs.to_owned(),
+        });
+        (self.rows.len() - 1) as u32
+    }
+
+    fn remove(&mut self, row: u32, dirs: &mut HashMap<Box<str>, (PathBuf, u32, u32)>) {
+        let idx = row as usize;
+        let last = self.rows.len() - 1;
+        self.dead += self.rows[idx].rel.len as usize;
+        self.rows.swap_remove(idx);
+        if idx != last {
+            let moved = self.rows[idx].rel.get(&self.text);
+            if let Some(dir) = dirs.get_mut(moved) {
+                dir.2 = idx as u32;
+            }
+        }
+    }
+
+    fn compact(&mut self) {
+        let mut text = String::with_capacity(self.text.len() - self.dead);
+        for row in &mut self.rows {
+            let rel = row.rel.get(&self.text);
+            row.rel = Span::of(&text, rel);
+            text.push_str(rel);
+        }
+        self.text = text;
+        self.dead = 0;
+    }
+
+    fn shrink(&mut self) {
+        self.compact();
+        self.rows.shrink_to_fit();
+        self.text.shrink_to_fit();
+    }
+}
+
+/// The scan-relevant fields of one symbol: its character mask and the name in the
+/// arena. Interleaved so a scan touches one cache line per candidate instead of three
+/// parallel arrays.
+#[derive(Clone, Copy)]
+pub(crate) struct SymHead {
+    pub mask: u64,
+    pub name: Span,
+}
+
+/// Index-wide symbol storage: one row per symbol in parallel arrays, with names and
+/// containers interned in a single arena. Each file points at a contiguous range.
+#[derive(Default)]
+pub(crate) struct SymTable {
+    head: Vec<SymHead>,
+    container: Vec<Span>,
+    kind: Vec<SymbolKind>,
+    range: Vec<Range>,
+    text: String,
+    dead_rows: usize,
+}
+
+impl SymTable {
+    #[inline]
+    pub(crate) fn name(&self, i: u32) -> &str {
+        self.head[i as usize].name.get(&self.text)
+    }
+
+    #[inline]
+    pub(crate) fn mask(&self, i: u32) -> u64 {
+        self.head[i as usize].mask
+    }
+
+    #[inline]
+    pub(crate) fn container(&self, i: u32) -> Option<&str> {
+        let span = self.container[i as usize];
+        (span.start != u32::MAX).then(|| span.get(&self.text))
+    }
+
+    /// The mask + name rows of a file's contiguous symbol range.
+    #[inline]
+    pub(crate) fn heads(&self, start: u32, len: u32) -> &[SymHead] {
+        let (start, end) = (start as usize, start as usize + len as usize);
+        &self.head[start..end]
+    }
+
+    #[inline]
+    pub(crate) fn kind(&self, i: u32) -> SymbolKind {
+        self.kind[i as usize]
+    }
+
+    #[inline]
+    pub(crate) fn range(&self, i: u32) -> Range {
+        self.range[i as usize]
+    }
+
+    fn intern(&mut self, s: &str) -> Span {
+        let span = Span::of(&self.text, s);
+        self.text.push_str(s);
+        span
+    }
+
+    /// Appends a file's symbols; they stay contiguous. Returns the start index
+    /// and the union of their masks.
+    fn push(&mut self, symbols: &[StoredSymbol]) -> (u32, u64) {
+        let start = self.head.len() as u32;
+        let mut agg_mask = 0u64;
+        for s in symbols {
+            let mask = char_mask(&s.name);
+            agg_mask |= mask;
+            let name = self.intern(&s.name);
+            let container = match &s.container {
+                Some(c) => self.intern(c),
+                None => Span::NONE,
+            };
+            self.head.push(SymHead { mask, name });
+            self.container.push(container);
+            self.kind.push(s.kind);
+            self.range.push(s.range);
+        }
+        (start, agg_mask)
+    }
+
+    /// Whether `symbols` would flatten to exactly the range at `start`.
+    fn same(&self, start: u32, len: u32, symbols: &[StoredSymbol]) -> bool {
+        len as usize == symbols.len()
+            && symbols.iter().enumerate().all(|(k, s)| {
+                let i = start + k as u32;
+                self.name(i) == s.name
+                    && self.container(i) == s.container.as_deref()
+                    && self.kind(i) == s.kind
+                    && self.range(i) == s.range
+            })
+    }
+
+    fn free(&mut self, _start: u32, len: u32) {
+        self.dead_rows += len as usize;
+    }
+
+    /// Rewrites the live rows in file order, reclaiming the space of replaced files.
+    /// `files` entries keep their range in sync; queries read rows, but persistence
+    /// and `FileEntry` accessors go through the entry.
+    fn compact(&mut self, rows: &mut [FileRow], files: &mut [Option<FileEntry>]) {
+        let mut text = String::with_capacity(self.text.len());
+        let mut head = Vec::with_capacity(self.head.len() - self.dead_rows);
+        let mut container = Vec::with_capacity(head.capacity());
+        let mut kind = Vec::with_capacity(head.capacity());
+        let mut range = Vec::with_capacity(head.capacity());
+        let mut live = 0u32;
+        for (slot, row) in rows.iter_mut().enumerate() {
+            if !row.live {
+                row.sym_start = 0;
+                continue;
+            }
+            let (start, end) = (row.sym_start, row.sym_start + row.sym_len);
+            row.sym_start = live;
+            if let Some(e) = files.get_mut(slot).and_then(Option::as_mut) {
+                e.sym_start = live;
+            }
+            for i in start..end {
+                let name_span = self.head[i as usize].name;
+                let name = name_span.get(&self.text);
+                head.push(SymHead { mask: self.head[i as usize].mask, name: Span::of(&text, name) });
+                text.push_str(name);
+                let container_span = self.container[i as usize];
+                if container_span.start == u32::MAX {
+                    container.push(Span::NONE);
+                } else {
+                    let c = container_span.get(&self.text);
+                    container.push(Span::of(&text, c));
+                    text.push_str(c);
+                }
+                kind.push(self.kind[i as usize]);
+                range.push(self.range[i as usize]);
+                live += 1;
+            }
+        }
+        self.head = head;
+        self.container = container;
+        self.kind = kind;
+        self.range = range;
+        self.text = text;
+        self.dead_rows = 0;
+    }
+
+    fn shrink(&mut self) {
+        self.head.shrink_to_fit();
+        self.container.shrink_to_fit();
+        self.kind.shrink_to_fit();
+        self.range.shrink_to_fit();
+        self.text.shrink_to_fit();
+    }
+}
+
 #[derive(Default)]
 pub(crate) struct IndexData {
     pub files: Vec<Option<FileEntry>>,
     by_path: HashMap<PathBuf, u32>,
     /// Every folder holding an indexed file at any depth, keyed by its `rel` with a
-    /// trailing `/`: its absolute path and the number of files below it.
-    pub dirs: HashMap<Box<str>, (PathBuf, u32)>,
+    /// trailing `/`: its absolute path, the number of files below it, and its row in
+    /// [`HotDirs`].
+    pub dirs: HashMap<Box<str>, (PathBuf, u32, u32)>,
+    /// Compact query-time view of `files`, kept in sync by `insert`/`remove`.
+    pub hot: HotFiles,
+    /// Compact query-time view of `dirs`, kept in sync by `insert`/`remove`.
+    pub dirs_hot: HotDirs,
+    /// Flattened symbols of every file, kept in sync by `insert`/`remove`.
+    pub syms: SymTable,
     free: Vec<u32>,
     pub file_count: u32,
     pub symbol_count: u32,
@@ -161,49 +553,124 @@ impl IndexData {
         self.by_path.get(path).copied()
     }
 
-    pub(crate) fn insert(&mut self, entry: FileEntry) {
-        let symbols = entry.symbols.len() as u32;
+    /// The persisted form of a file, rebuilt from [`IndexData::syms`].
+    pub(crate) fn record(&self, e: &FileEntry) -> FileRecord {
+        FileRecord {
+            mtime: e.mtime,
+            size: e.size,
+            hash: e.hash,
+            symbols: self
+                .symbols_of(e)
+                .map(|s| StoredSymbol {
+                    name: s.name.to_owned(),
+                    kind: s.kind,
+                    container: s.container.map(str::to_owned),
+                    range: s.range,
+                })
+                .collect(),
+            ignored: e.ignored,
+        }
+    }
+
+    pub(crate) fn record_of(&self, path: &Path) -> Option<FileRecord> {
+        self.get(path).map(|e| self.record(e))
+    }
+
+    /// The symbols of one file, in declaration order.
+    pub(crate) fn symbols_of<'a>(&'a self, e: &'a FileEntry) -> impl Iterator<Item = SymRef<'a>> + 'a {
+        let syms = &self.syms;
+        (e.sym_start..e.sym_start + e.sym_len).map(move |i| SymRef {
+            name: syms.name(i),
+            kind: syms.kind(i),
+            container: syms.container(i),
+            range: syms.range(i),
+        })
+    }
+
+    pub(crate) fn insert(&mut self, mut entry: FileEntry, symbols: Vec<StoredSymbol>) {
+        let sym_len = symbols.len() as u32;
         if let Some(&slot) = self.by_path.get(&entry.path) {
-            let old = self.files[slot as usize].replace(entry);
-            self.symbol_count -= old.map_or(0, |o| o.symbols.len() as u32);
-            self.symbol_count += symbols;
+            let old = self.files[slot as usize].as_ref().expect("indexed slots are live");
+            let old_len = old.sym_len;
+            // Rescans and saves that re-parse to the same symbols reuse the range; a
+            // same-path replacement then costs nothing in the symbol table.
+            let (sym_start, sym_mask) = if self.syms.same(old.sym_start, old_len, &symbols) {
+                (old.sym_start, self.hot.rows[slot as usize].sym_mask)
+            } else {
+                self.syms.free(old.sym_start, old_len);
+                self.syms.push(&symbols)
+            };
+            entry.sym_start = sym_start;
+            entry.sym_len = sym_len;
+            self.symbol_count = self.symbol_count - old_len + sym_len;
+            self.hot.update(slot, &entry, sym_mask);
+            self.files[slot as usize] = Some(entry);
+            self.compact_if_needed();
             return;
         }
+        let (sym_start, sym_mask) = self.syms.push(&symbols);
+        entry.sym_start = sym_start;
+        entry.sym_len = sym_len;
         let slot = match self.free.pop() {
-            Some(slot) => {
-                self.files[slot as usize] = Some(entry);
-                slot
-            }
+            Some(slot) => slot,
             None => {
-                self.files.push(Some(entry));
+                self.files.push(None);
                 (self.files.len() - 1) as u32
             }
         };
-        let path = self.files[slot as usize].as_ref().map(|e| e.path.clone()).unwrap_or_default();
+        let path = entry.path.clone();
+        let (name_start, name_mask, rel_mask) = (entry.name_start, entry.name_mask, entry.rel_mask);
+        let rel = self.hot.append(&entry.rel);
+        self.hot.set(
+            slot,
+            FileRow {
+                rel,
+                name_start,
+                sym_start: entry.sym_start,
+                sym_len,
+                sym_mask,
+                rel_mask,
+                name_mask,
+                dir_mask: char_mask(&entry.rel[..name_start as usize]),
+                ascii: entry.rel.is_ascii(),
+                live: true,
+            },
+        );
+        self.files[slot as usize] = Some(entry);
         if let Some(e) = &self.files[slot as usize] {
             for (rel, abs) in ancestors(e) {
-                self.dirs.entry(rel.into()).or_insert_with(|| (abs.to_owned(), 0)).1 += 1;
+                if let Some(dir) = self.dirs.get_mut(rel) {
+                    dir.1 += 1;
+                } else {
+                    let row = self.dirs_hot.push(rel, abs);
+                    self.dirs.insert(rel.into(), (abs.to_owned(), 1, row));
+                }
             }
         }
         self.by_path.insert(path, slot);
         self.file_count += 1;
-        self.symbol_count += symbols;
+        self.symbol_count += sym_len;
+        self.compact_if_needed();
     }
 
     pub(crate) fn remove(&mut self, path: &Path) -> Option<FileEntry> {
         let slot = self.by_path.remove(path)?;
         let old = self.files[slot as usize].take()?;
         self.free.push(slot);
+        self.hot.remove(slot);
+        self.syms.free(old.sym_start, old.sym_len);
         for (rel, _) in ancestors(&old) {
-            if let Some(d) = self.dirs.get_mut(rel) {
-                d.1 -= 1;
-                if d.1 == 0 {
-                    self.dirs.remove(rel);
-                }
+            let Some(dir) = self.dirs.get_mut(rel) else { continue };
+            dir.1 -= 1;
+            if dir.1 > 0 {
+                continue;
             }
+            let Some((_, _, row)) = self.dirs.remove(rel) else { continue };
+            self.dirs_hot.remove(row, &mut self.dirs);
         }
         self.file_count -= 1;
-        self.symbol_count -= old.symbols.len() as u32;
+        self.symbol_count -= old.sym_len;
+        self.compact_if_needed();
         Some(old)
     }
 
@@ -213,6 +680,19 @@ impl IndexData {
         doomed.into_iter().filter(|p| self.remove(p).is_some()).collect()
     }
 
+    /// Reclaims the space of replaced/removed files once it dominates a table.
+    fn compact_if_needed(&mut self) {
+        if self.hot.dead_text > 1 << 16 && self.hot.dead_text * 2 > self.hot.text.len() {
+            self.hot.compact();
+        }
+        if self.syms.dead_rows > 4096 && self.syms.dead_rows * 2 > self.syms.head.len() {
+            self.syms.compact(&mut self.hot.rows, &mut self.files);
+        }
+        if self.dirs_hot.dead > 1 << 16 && self.dirs_hot.dead * 2 > self.dirs_hot.text.len() {
+            self.dirs_hot.compact();
+        }
+    }
+
     /// Releases spare capacity (after large deletions).
     pub(crate) fn shrink(&mut self) {
         while matches!(self.files.last(), Some(None)) {
@@ -221,6 +701,11 @@ impl IndexData {
             self.free.retain(|&s| s != last);
         }
         self.files.shrink_to_fit();
+        self.hot.rows.truncate(self.files.len());
+        self.hot.shrink();
+        self.dirs_hot.shrink();
+        self.syms.compact(&mut self.hot.rows, &mut self.files);
+        self.syms.shrink();
         self.free.shrink_to_fit();
         self.by_path.shrink_to_fit();
         self.dirs.shrink_to_fit();
@@ -248,7 +733,7 @@ fn ancestors(e: &FileEntry) -> impl Iterator<Item = (&str, &Path)> {
 mod tests {
     use super::*;
 
-    fn entry(path: &str, symbols: usize) -> FileEntry {
+    fn entry(path: &str, symbols: usize) -> (FileEntry, Vec<StoredSymbol>) {
         let record = FileRecord {
             symbols: (0..symbols)
                 .map(|i| StoredSymbol {
@@ -263,48 +748,101 @@ mod tests {
         FileEntry::new(PathBuf::from("/r").join(path), path.to_owned(), record)
     }
 
+    fn insert(d: &mut IndexData, path: &str, symbols: usize) {
+        let (e, s) = entry(path, symbols);
+        d.insert(e, s);
+    }
+
+    /// The compact tables must always mirror the entries they were derived from.
+    fn assert_consistent(d: &IndexData) {
+        assert_eq!(d.hot.rows.len(), d.files.len(), "one hot row per slot");
+        assert_eq!(d.hot.rows.iter().filter(|r| r.live).count(), d.file_count as usize, "live rows are files");
+        for (slot, e) in d.files.iter().enumerate() {
+            let Some(e) = e else {
+                assert!(d.hot.row(slot).is_none(), "free slot {slot} has no row");
+                continue;
+            };
+            let row = d.hot.row(slot).unwrap_or_else(|| panic!("slot {slot} has a row"));
+            assert_eq!(row.rel(d.hot.text()), &*e.rel);
+            assert_eq!(row.name(d.hot.text()), e.name());
+            assert_eq!(row.dir(d.hot.text()), e.dir());
+            assert_eq!(row.name_mask, char_mask(e.name()));
+            assert_eq!(row.rel_mask, char_mask(&e.rel));
+            assert_eq!(row.dir_mask, char_mask(e.dir()));
+            assert_eq!(row.ascii, e.rel.is_ascii());
+            assert_eq!(row.sym_start, e.sym_start);
+            assert_eq!(row.sym_len, e.sym_len);
+            assert_eq!(row.sym_mask, d.symbols_of(e).fold(0u64, |m, s| m | char_mask(s.name)));
+            assert_eq!(d.syms.head.len(), d.syms.container.len());
+            assert_eq!(d.syms.head.len(), d.syms.kind.len());
+            assert_eq!(d.syms.head.len(), d.syms.range.len());
+            assert!(e.sym_len == 0 || (e.sym_start as usize) < d.syms.head.len());
+            assert!(e.sym_start + e.sym_len <= d.syms.head.len() as u32);
+        }
+        for (rel, (path, count, row)) in &d.dirs {
+            let row = &d.dirs_hot.rows[*row as usize];
+            assert_eq!(row.rel(d.dirs_hot.text()), &**rel);
+            assert_eq!(&row.path, path);
+            assert!(*count > 0);
+            let trimmed = &rel[..rel.len() - 1];
+            let name = &trimmed[row.name_start as usize..];
+            assert_eq!(row.name_mask, char_mask(name));
+            assert_eq!(row.rel_mask, char_mask(trimmed));
+        }
+        assert_eq!(d.dirs.len(), d.dirs_hot.rows.len());
+        assert_eq!(d.symbol_count, d.files.iter().flatten().map(|e| e.sym_len).sum::<u32>());
+    }
+
     #[test]
     fn dirs_follow_inserts_and_removals() {
         let mut d = IndexData::default();
-        d.insert(entry("a/b/c.rs", 0));
-        d.insert(entry("a/d.rs", 0));
-        d.insert(entry("a/d.rs", 0));
-        d.insert(entry("top.rs", 0));
+        insert(&mut d, "a/b/c.rs", 0);
+        insert(&mut d, "a/d.rs", 0);
+        insert(&mut d, "a/d.rs", 0);
+        insert(&mut d, "top.rs", 0);
         let mut dirs: Vec<_> = d.dirs.iter().map(|(k, v)| (k.to_string(), v.1)).collect();
         dirs.sort();
         assert_eq!(dirs, [("a/".into(), 2), ("a/b/".into(), 1)]);
         assert_eq!(d.dirs["a/b/"].0, PathBuf::from("/r/a/b"));
+        assert_consistent(&d);
         d.remove(Path::new("/r/a/b/c.rs"));
         assert!(!d.dirs.contains_key("a/b/"));
+        assert_consistent(&d);
         d.remove_tree(Path::new("/r/a"));
         assert!(d.dirs.is_empty());
+        assert_consistent(&d);
     }
 
     #[test]
     fn insert_replace_remove_keep_counts() {
         let mut d = IndexData::default();
-        d.insert(entry("a/b.rs", 2));
-        d.insert(entry("c.rs", 1));
+        insert(&mut d, "a/b.rs", 2);
+        insert(&mut d, "c.rs", 1);
         assert_eq!((d.file_count, d.symbol_count), (2, 3));
-        d.insert(entry("a/b.rs", 5));
+        insert(&mut d, "a/b.rs", 5);
         assert_eq!((d.file_count, d.symbol_count), (2, 6));
+        assert_consistent(&d);
         assert!(d.remove(Path::new("/r/c.rs")).is_some());
         assert_eq!((d.file_count, d.symbol_count), (1, 5));
-        d.insert(entry("d.rs", 0));
+        assert_consistent(&d);
+        insert(&mut d, "d.rs", 0);
         assert_eq!(d.files.len(), 2, "slot reused");
+        assert_consistent(&d);
         assert_eq!(d.remove_tree(Path::new("/r/a")), vec![PathBuf::from("/r/a/b.rs")]);
         assert_eq!((d.file_count, d.symbol_count), (1, 0));
         let e = d.get(Path::new("/r/d.rs")).unwrap();
         assert_eq!((e.name(), e.dir()), ("d.rs", ""));
-        d.insert(entry("e.rs", 1));
-        d.insert(entry("f.rs", 1));
+        insert(&mut d, "e.rs", 1);
+        insert(&mut d, "f.rs", 1);
         d.remove(Path::new("/r/e.rs"));
         d.remove(Path::new("/r/f.rs"));
         d.shrink();
+        assert_consistent(&d);
         assert_eq!(d.files.len(), 2, "trailing free slot dropped");
         assert_eq!(d.free, vec![0]);
-        d.insert(entry("g.rs", 1));
+        insert(&mut d, "g.rs", 1);
         assert_eq!((d.file_count, d.files.len()), (2, 2));
+        assert_consistent(&d);
     }
 
     #[test]
@@ -312,4 +850,65 @@ mod tests {
         assert_eq!(char_mask("ab") & char_mask("Bad"), char_mask("ab"));
         assert_ne!(char_mask("z") & char_mask("abc"), char_mask("z"));
     }
+
+    fn insert_symbols(d: &mut IndexData, path: &str, symbols: Vec<StoredSymbol>) {
+        let record = FileRecord { symbols, ..Default::default() };
+        let (e, s) = FileEntry::new(PathBuf::from("/r").join(path), path.to_owned(), record);
+        d.insert(e, s);
+    }
+
+    fn symbol(n: &str) -> StoredSymbol {
+        StoredSymbol { name: n.to_owned(), kind: SymbolKind::Function, container: None, range: Range::default() }
+    }
+
+    #[test]
+    fn compaction_keeps_entries_and_records_in_sync() {
+        let mut d = IndexData::default();
+        insert(&mut d, "a.rs", 3);
+        insert(&mut d, "b/c.rs", 2);
+        insert_symbols(&mut d, "a.rs", vec![symbol("fresh")]);
+        d.shrink();
+        assert_consistent(&d);
+        assert_eq!(d.syms.head.len() as u32, d.symbol_count, "compaction drops dead symbol rows");
+        let names = |d: &IndexData, p: &str| -> Vec<String> {
+            let e = d.get(Path::new(p)).unwrap();
+            d.record(e).symbols.into_iter().map(|s| s.name).collect()
+        };
+        assert_eq!(names(&d, "/r/a.rs"), ["fresh"]);
+        assert_eq!(names(&d, "/r/b/c.rs"), ["s0", "s1"]);
+        assert_eq!(d.symbol_count, 3);
+    }
+
+    #[test]
+    fn large_replacements_reclaim_symbol_storage() {
+        let mut d = IndexData::default();
+        insert_symbols(&mut d, "a.rs", (0..5_000).map(|i| symbol(&format!("old{i}"))).collect());
+        assert_eq!(d.syms.head.len(), 5_000);
+        insert_symbols(&mut d, "a.rs", vec![symbol("fresh")]);
+        assert_eq!(d.syms.head.len(), 1, "dead symbol rows are reclaimed");
+        assert_eq!((d.symbol_count, d.file_count), (1, 1));
+        assert_consistent(&d);
+    }
+
+    #[test]
+    fn tree_removal_leaves_no_hot_rows_or_dirs() {
+        let mut d = IndexData::default();
+        insert(&mut d, "a/b/one.rs", 2);
+        insert(&mut d, "a/b/two.rs", 3);
+        insert(&mut d, "a/three.rs", 1);
+        insert(&mut d, "elsewhere/four.rs", 1);
+        assert_eq!(d.remove_tree(Path::new("/r/a")).len(), 3);
+        assert_consistent(&d);
+        assert_eq!(d.hot.rows.iter().filter(|r| r.live).count(), 1);
+        assert!(d.hot.row(0).is_none(), "removed slots have no live row");
+        assert_eq!(d.dirs.len(), 1, "elsewhere/ only");
+        assert_eq!(d.dirs_hot.rows.len(), 1);
+        assert_eq!(d.symbol_count, 1);
+        d.shrink();
+        assert_eq!(d.syms.head.len() as u32, d.symbol_count);
+        // Slots are reusable and the new row replaces the tombstone.
+        insert(&mut d, "a/five.rs", 2);
+        assert_consistent(&d);
+        assert_eq!(d.file_count, 2);
+    }
 }

crates/ide-index/src/lib.rs

@@ -199,12 +199,11 @@ impl ProjectIndex {
             return None;
         }
         Some(
-            file.symbols
-                .iter()
+            data.symbols_of(file)
                 .map(|s| ide_language::SymbolTag {
                     name: s.name.to_string(),
                     kind: s.kind,
-                    container: s.container.as_ref().map(ToString::to_string),
+                    container: s.container.map(ToString::to_string),
                     range: s.range,
                 })
                 .collect(),
@@ -231,7 +230,7 @@ impl ProjectIndex {
     pub fn find_files(&self, query: &str, limit: usize) -> Vec<FileMatch> {
         let recent = self.shared.recent.lock().clone();
         let d = self.shared.data.read();
-        matching::find_files(&d, &matching::Recents { paths: &recent }, query, limit)
+        matching::find_files(&d, &matching::Recents::new(&recent), query, limit)
     }
 
     /// All indexed files with this exact basename, for resolving printed source locations.
@@ -274,7 +273,7 @@ impl ProjectIndex {
     pub fn find_symbols(&self, query: &str, filter: SymbolFilter, limit: usize) -> Vec<SymbolMatch> {
         let recent = self.shared.recent.lock().clone();
         let d = self.shared.data.read();
-        matching::find_symbols(&d, &matching::Recents { paths: &recent }, query, filter, limit)
+        matching::find_symbols(&d, &matching::Recents::new(&recent), query, filter, limit)
     }
 
     /// Scoped symbol search with cooperative interruption, including lock waits.
@@ -303,15 +302,7 @@ impl ProjectIndex {
                 break data;
             }
         };
-        matching::find_symbols_until(
-            &data,
-            &matching::Recents { paths: &recent },
-            query,
-            filter,
-            limit,
-            include,
-            stopped,
-        )
+        matching::find_symbols_until(&data, &matching::Recents::new(&recent), query, filter, limit, include, stopped)
     }
 
     /// Symbols named exactly `name` (of `kind`, if given): `.card` selectors for `class="card"`.
@@ -523,7 +514,8 @@ pub mod bench_support {
                     })
                     .collect();
                 let record = FileRecord { symbols, ..Default::default() };
-                data.insert(FileEntry::new(PathBuf::from("/bench").join(&rel), rel, record));
+                let (entry, symbols) = FileEntry::new(PathBuf::from("/bench").join(&rel), rel, record);
+                data.insert(entry, symbols);
             }
             let recent = data.paths().take(MAX_RECENT).cloned().collect();
             Self { data, recent }
@@ -538,7 +530,7 @@ pub mod bench_support {
         }
 
         pub fn find_files(&self, query: &str, limit: usize) -> Vec<FileMatch> {
-            matching::find_files(&self.data, &matching::Recents { paths: &self.recent }, query, limit)
+            matching::find_files(&self.data, &matching::Recents::new(&self.recent), query, limit)
         }
 
         pub fn find_dirs(&self, query: &str, limit: usize) -> Vec<FileMatch> {
@@ -546,7 +538,7 @@ pub mod bench_support {
         }
 
         pub fn find_symbols(&self, query: &str, filter: SymbolFilter, limit: usize) -> Vec<SymbolMatch> {
-            matching::find_symbols(&self.data, &matching::Recents { paths: &self.recent }, query, filter, limit)
+            matching::find_symbols(&self.data, &matching::Recents::new(&self.recent), query, filter, limit)
         }
     }
 }

crates/ide-index/src/matching.rs

@@ -4,14 +4,19 @@
 //! (bit-mask pre-filter, nucleo score, exact/prefix boosts) and keeps the best
 //! few; the survivors then get match indices, CamelHump and recency boosts and
 //! are re-sorted.
+//!
+//! The scan streams the compact tables in `data` (`HotFiles`/`HotDirs`/`SymTable`):
+//! only the hot fields per candidate and strings from contiguous arenas, with the
+//! thread-local matcher and one UTF-32 buffer per scan rather than per candidate.
 
-use crate::data::{FileEntry, IndexData, char_mask};
+use crate::data::{DirRow, FileEntry, FileRow, IndexData, SymTable, char_mask};
 use crate::{FileMatch, SymbolFilter, SymbolMatch};
 use ide_core::SymbolKind;
 use nucleo_matcher::{Config, Matcher, Utf32Str, Utf32String};
 use rayon::prelude::*;
 use std::cell::RefCell;
 use std::cmp::Ordering;
+use std::collections::HashMap;
 use std::path::{Path, PathBuf};
 
 const TIER_NAME: u32 = 1 << 20;
@@ -54,6 +59,11 @@ impl Needle {
         m.fuzzy_match(Utf32Str::new(hay, buf), self.utf32.slice(..)).map(u32::from)
     }
 
+    /// `hay` is pure ASCII: skip `Utf32Str::new`'s check and UTF-32 conversion.
+    fn score_ascii(&self, m: &mut Matcher, hay: &str) -> Option<u32> {
+        m.fuzzy_match(Utf32Str::Ascii(hay.as_bytes()), self.utf32.slice(..)).map(u32::from)
+    }
+
     fn indices(&self, m: &mut Matcher, hay: &str, buf: &mut Vec<char>, out: &mut Vec<u32>) -> Option<u32> {
         out.clear();
         let s = m.fuzzy_indices(Utf32Str::new(hay, buf), self.utf32.slice(..), out).map(u32::from);
@@ -105,6 +115,9 @@ struct Cand {
     slot: u32,
     sym: u32,
     score: u32,
+    /// Candidate name/rel length: the first tie-break key, cached so ranking a pool
+    /// does not chase it through the tables.
+    len: u32,
 }
 
 fn keep_best(mut v: Vec<Cand>, k: usize, tiebreak: &impl Fn(&Cand, &Cand) -> Ordering) -> Vec<Cand> {
@@ -119,7 +132,7 @@ fn scan(
     data: &IndexData,
     pool: usize,
     tiebreak: &(impl Fn(&Cand, &Cand) -> Ordering + Sync),
-    per_file: impl Fn(u32, &FileEntry, &mut Vec<Cand>) + Sync,
+    per_file: impl Fn(u32, &FileRow, &mut Matcher, &mut Vec<Cand>) + Sync,
 ) -> Vec<Cand> {
     scan_until(data, pool, tiebreak, &|| false, per_file).unwrap_or_default()
 }
@@ -129,18 +142,22 @@ fn scan_until(
     pool: usize,
     tiebreak: &(impl Fn(&Cand, &Cand) -> Ordering + Sync),
     stopped: &(impl Fn() -> bool + Sync),
-    per_file: impl Fn(u32, &FileEntry, &mut Vec<Cand>) + Sync,
+    per_file: impl Fn(u32, &FileRow, &mut Matcher, &mut Vec<Cand>) + Sync,
 ) -> Option<Vec<Cand>> {
-    data.files
+    // One row per slot, so this is exactly the old scan over `files`: same item
+    // order and count, and free slots are skipped exactly like `None` was, keeping
+    // the pruning boundaries (and therefore the candidate pool) unchanged.
+    data.hot
+        .rows
         .par_iter()
         .enumerate()
         .with_min_len(256)
-        .try_fold(Vec::new, |mut acc, (slot, e)| {
+        .try_fold(Vec::new, |mut acc, (slot, row)| {
             if stopped() {
                 return None;
             }
-            if let Some(e) = e {
-                per_file(slot as u32, e, &mut acc);
+            if row.live {
+                with_matcher(|m| per_file(slot as u32, row, m, &mut acc));
                 if acc.len() >= pool * 2 {
                     acc = keep_best(acc, pool, tiebreak);
                 }
@@ -155,15 +172,22 @@ fn scan_until(
 
 pub(crate) struct Recents<'a> {
     pub paths: &'a [PathBuf],
+    /// Position of each path, so ranking a survivor does not scan the list.
+    /// Duplicates keep their first position, like `position`.
+    ranks: HashMap<&'a Path, usize>,
 }
 
-impl Recents<'_> {
-    fn rank(&self, path: &std::path::Path) -> Option<usize> {
-        self.paths.iter().position(|p| p == path)
+impl<'a> Recents<'a> {
+    pub(crate) fn new(paths: &'a [PathBuf]) -> Self {
+        let mut ranks = HashMap::with_capacity(paths.len());
+        for (i, p) in paths.iter().enumerate() {
+            ranks.entry(p.as_path()).or_insert(i);
+        }
+        Self { paths, ranks }
     }
 
-    fn bonus(&self, path: &std::path::Path) -> u32 {
-        self.rank(path).map_or(0, |r| RECENT_MAX.saturating_sub(r as u32 * 12))
+    fn bonus(&self, path: &Path) -> u32 {
+        self.ranks.get(path).map_or(0, |&r| RECENT_MAX.saturating_sub(r as u32 * 12))
     }
 }
 
@@ -209,29 +233,31 @@ pub(crate) fn find_files(data: &IndexData, recents: &Recents, query: &str, limit
         Some((dir, name)) => FileQuery::Path { dir: Needle::new(dir), name: Needle::new(name) },
         None => FileQuery::Name(Needle::new(&q)),
     };
-    let tiebreak = |a: &Cand, b: &Cand| {
-        let (ea, eb) = (file(data, a.slot), file(data, b.slot));
-        ea.rel.len().cmp(&eb.rel.len()).then_with(|| ea.rel.cmp(&eb.rel))
-    };
+    let tiebreak = |a: &Cand, b: &Cand| a.len.cmp(&b.len).then_with(|| data.hot.rel(a.slot).cmp(data.hot.rel(b.slot)));
     let pool = limit * 4 + 64;
-    let mut cands = scan(data, pool, &tiebreak, |slot, e, acc| {
+    let mut cands = scan(data, pool, &tiebreak, |slot, row, m, acc| {
         let mut buf = Vec::new();
-        if let Some(score) = with_matcher(|m| base_file_score(m, &fq, e, &mut buf)) {
-            acc.push(Cand { slot, sym: u32::MAX, score });
+        if let Some(score) = base_file_score(m, &fq, row, data.hot.text(), &mut buf) {
+            acc.push(Cand { slot, sym: u32::MAX, score, len: row.rel.len });
         }
     });
     // Recent files always compete for the final ranking.
-    for p in recents.paths {
-        if let Some(e) = data.get(p) {
+    with_matcher(|m| {
+        let mut buf = Vec::new();
+        for p in recents.paths {
+            if data.get(p).is_none() {
+                continue;
+            }
             let Some(slot) = data.slot(p) else { continue };
-            if !cands.iter().any(|c| c.slot == slot) {
-                let mut buf = Vec::new();
-                if let Some(score) = with_matcher(|m| base_file_score(m, &fq, e, &mut buf)) {
-                    cands.push(Cand { slot, sym: u32::MAX, score });
-                }
+            if cands.iter().any(|c| c.slot == slot) {
+                continue;
+            }
+            let Some(row) = data.hot.row_of_slot(slot) else { continue };
+            if let Some(score) = base_file_score(m, &fq, row, data.hot.text(), &mut buf) {
+                cands.push(Cand { slot, sym: u32::MAX, score, len: row.rel.len });
             }
         }
-    }
+    });
     let mut out: Vec<(u32, &FileEntry, Vec<u32>)> = with_matcher(|m| {
         let mut buf = Vec::new();
         cands
@@ -273,30 +299,46 @@ pub(crate) fn find_dirs(data: &IndexData, query: &str, limit: usize) -> Vec<File
     }
     let by_path = q.contains('/');
     let needle = Needle::new(q.trim_end_matches('/'));
+    let text = data.dirs_hot.text();
     // (score, rel without the trailing `/`, char offset of the name when it matched by name)
-    let score = |m: &mut Matcher, buf: &mut Vec<char>, rel: &str| -> Option<(u32, Option<u32>)> {
-        let trimmed = &rel[..rel.len() - 1];
-        let start = trimmed.rfind('/').map_or(0, |i| i + 1);
-        let name = &trimmed[start..];
-        if !by_path
-            && needle.mask & char_mask(name) == needle.mask
-            && let Some(s) = needle.score(m, name, buf)
-        {
-            return Some((TIER_NAME + s * 4 + needle.name_boost(name), Some(trimmed[..start].chars().count() as u32)));
-        }
-        if needle.mask & char_mask(trimmed) != needle.mask {
-            return None;
-        }
-        needle.score(m, trimmed, buf).map(|s| (s, None))
-    };
-    let mut best: Vec<(u32, &str, &Path, Option<u32>)> = data
-        .dirs
+    let (mut best, _): (Vec<_>, Vec<char>) = data
+        .dirs_hot
+        .rows
         .par_iter()
-        .filter_map(|(rel, (path, _))| {
-            let mut buf = Vec::new();
-            with_matcher(|m| score(m, &mut buf, rel)).map(|(s, at)| (s, &**rel, path.as_path(), at))
-        })
-        .collect();
+        .fold(
+            || (Vec::new(), Vec::new()),
+            |(mut found, mut buf), row: &DirRow| {
+                let rel = row.rel(text);
+                let trimmed = &rel[..rel.len() - 1];
+                let name = &trimmed[row.name_start as usize..];
+                with_matcher(|m| {
+                    let hit = if !by_path
+                        && needle.mask & row.name_mask == needle.mask
+                        && let Some(s) = needle.score(m, name, &mut buf)
+                    {
+                        Some((
+                            TIER_NAME + s * 4 + needle.name_boost(name),
+                            Some(trimmed[..row.name_start as usize].chars().count() as u32),
+                        ))
+                    } else if needle.mask & row.rel_mask != needle.mask {
+                        None
+                    } else {
+                        needle.score(m, trimmed, &mut buf).map(|s| (s, None))
+                    };
+                    if let Some((s, at)) = hit {
+                        found.push((s, rel, row.path.as_path(), at));
+                    }
+                });
+                (found, buf)
+            },
+        )
+        .reduce(
+            || (Vec::new(), Vec::new()),
+            |mut a, b| {
+                a.0.extend(b.0);
+                a
+            },
+        );
     let order = |a: &(u32, &str, &Path, Option<u32>), b: &(u32, &str, &Path, Option<u32>)| {
         b.0.cmp(&a.0).then_with(|| a.1.len().cmp(&b.1.len())).then_with(|| a.1.cmp(b.1))
     };
@@ -338,33 +380,39 @@ fn file(data: &IndexData, slot: u32) -> &FileEntry {
     data.files[slot as usize].as_ref().expect("candidate slots are live")
 }
 
-fn base_file_score(m: &mut Matcher, q: &FileQuery, e: &FileEntry, buf: &mut Vec<char>) -> Option<u32> {
+fn base_file_score(m: &mut Matcher, q: &FileQuery, row: &FileRow, text: &str, buf: &mut Vec<char>) -> Option<u32> {
+    // Strings are sliced only once their mask passes, so a rejected row costs two masks.
     match q {
         FileQuery::Name(n) => {
-            if n.mask & e.name_mask == n.mask
-                && let Some(s) = n.score(m, e.name(), buf)
-            {
-                return Some(TIER_NAME + s * 4 + n.name_boost(e.name()));
+            if n.mask & row.name_mask == n.mask {
+                let name = row.name(text);
+                let s = if row.ascii { n.score_ascii(m, name) } else { n.score(m, name, buf) };
+                if let Some(s) = s {
+                    return Some(TIER_NAME + s * 4 + n.name_boost(name));
+                }
             }
-            if n.mask & e.rel_mask == n.mask {
-                return n.score(m, &e.rel, buf);
+            if n.mask & row.rel_mask == n.mask {
+                let rel = row.rel(text);
+                return if row.ascii { n.score_ascii(m, rel) } else { n.score(m, rel, buf) };
             }
             None
         }
-        FileQuery::Path { dir, name } => {
-            let name_score = if name.is_empty() {
+        FileQuery::Path { dir, name: n } => {
+            let name_score = if n.is_empty() {
                 0
             } else {
-                if name.mask & e.name_mask != name.mask {
+                if n.mask & row.name_mask != n.mask {
                     return None;
                 }
-                name.score(m, e.name(), buf)? * 4 + name.name_boost(e.name())
+                let name = row.name(text);
+                let s = if row.ascii { n.score_ascii(m, name) } else { n.score(m, name, buf) }?;
+                s * 4 + n.name_boost(name)
             };
-            let dir_str = e.dir();
-            if dir.mask & char_mask(dir_str) != dir.mask {
+            if dir.mask & row.dir_mask != dir.mask {
                 return None;
             }
-            let dir_score = dir.score(m, dir_str, buf)?;
+            let dir_str = row.dir(text);
+            let dir_score = if row.ascii { dir.score_ascii(m, dir_str) } else { dir.score(m, dir_str, buf) }?;
             Some(TIER_NAME + name_score + dir_score)
         }
     }
@@ -396,22 +444,21 @@ fn symbol_score(
     m: &mut Matcher,
     name: &Needle,
     container: Option<&Needle>,
-    s: &crate::data::Sym,
+    syms: &SymTable,
+    i: u32,
     buf: &mut Vec<char>,
 ) -> Option<u32> {
-    if name.mask & s.mask != name.mask {
-        return None;
-    }
-    let mut score = if name.is_empty() { 0 } else { name.score(m, &s.name, buf)? * 4 };
-    score += name.name_boost(&s.name);
+    let symbol = syms.name(i);
+    let mut score = if name.is_empty() { 0 } else { name.score(m, symbol, buf)? * 4 };
+    score += name.name_boost(symbol);
     if let Some(cq) = container {
-        let c = s.container.as_deref()?;
+        let c = syms.container(i)?;
         if cq.mask & char_mask(c) != cq.mask {
             return None;
         }
         score += cq.score(m, c, buf)? + cq.name_boost(c) / 4;
     }
-    if s.kind.is_type_like() {
+    if syms.kind(i).is_type_like() {
         score += TYPE_LIKE;
     }
     Some(score)
@@ -455,30 +502,35 @@ pub(crate) fn find_symbols_until(
     let (container_q, name_q) = split_symbol_query(&q);
     let name = Needle::new(name_q);
     let container = container_q.map(Needle::new);
-    let sym = |c: &Cand| &file(data, c.slot).symbols[c.sym as usize];
-    let tiebreak = |a: &Cand, b: &Cand| {
-        let (sa, sb) = (sym(a), sym(b));
-        sa.name.len().cmp(&sb.name.len()).then_with(|| file(data, a.slot).rel.cmp(&file(data, b.slot).rel))
-    };
+    let syms = &data.syms;
+    let tiebreak = |a: &Cand, b: &Cand| a.len.cmp(&b.len).then_with(|| data.hot.rel(a.slot).cmp(data.hot.rel(b.slot)));
     let pool = limit * 4 + 64;
-    let cands = scan_until(data, pool, &tiebreak, stopped, |slot, e, acc| {
-        if e.symbols.is_empty() || !include(&e.path) {
+    let cands = scan_until(data, pool, &tiebreak, stopped, |slot, row, m, acc| {
+        // Whole-file pre-filter: when the union of the file's symbol masks
+        // already misses a query character, no symbol can match.
+        if row.sym_len == 0 || name.mask & row.sym_mask != name.mask {
             return;
         }
-        with_matcher(|m| {
-            let mut buf = Vec::new();
-            for (i, s) in e.symbols.iter().enumerate() {
-                if stopped() {
-                    break;
-                }
-                if filter == SymbolFilter::Types && !s.kind.is_type_like() {
-                    continue;
-                }
-                if let Some(score) = symbol_score(m, &name, container.as_ref(), s, &mut buf) {
-                    acc.push(Cand { slot, sym: i as u32, score });
-                }
+        let e = file(data, slot);
+        if !include(&e.path) {
+            return;
+        }
+        let mut buf = Vec::new();
+        for (k, head) in syms.heads(row.sym_start, row.sym_len).iter().enumerate() {
+            if stopped() {
+                break;
             }
-        });
+            if filter == SymbolFilter::Types && !syms.kind(row.sym_start + k as u32).is_type_like() {
+                continue;
+            }
+            if name.mask & head.mask != name.mask {
+                continue;
+            }
+            let i = row.sym_start + k as u32;
+            if let Some(score) = symbol_score(m, &name, container.as_ref(), syms, i, &mut buf) {
+                acc.push(Cand { slot, sym: i, score, len: head.name.len });
+            }
+        }
     })?;
     if stopped() {
         return None;
@@ -489,33 +541,32 @@ pub(crate) fn find_symbols_until(
             .into_iter()
             .take_while(|_| !stopped())
             .filter_map(|c| {
-                let s = sym(&c);
+                let symbol = syms.name(c.sym);
                 let e = file(data, c.slot);
                 let mut idx = Vec::new();
                 if !name.is_empty() {
-                    name.indices(m, &s.name, &mut buf, &mut idx)?;
+                    name.indices(m, symbol, &mut buf, &mut idx)?;
                 }
-                let bonus = hump_bonus(&s.name, &idx) + recents.bonus(&e.path) / 4;
+                let bonus = hump_bonus(symbol, &idx) + recents.bonus(&e.path) / 4;
                 Some((c.score + bonus, c, idx))
             })
             .collect()
     });
     out.sort_by(|a, b| {
-        b.0.cmp(&a.0).then_with(|| tiebreak(&a.1, &b.1)).then_with(|| sym(&a.1).range.cmp(&sym(&b.1).range))
+        b.0.cmp(&a.0).then_with(|| tiebreak(&a.1, &b.1)).then_with(|| syms.range(a.1.sym).cmp(&syms.range(b.1.sym)))
     });
     out.truncate(limit);
     let results = out
         .into_iter()
         .map(|(score, c, indices)| {
             let e = file(data, c.slot);
-            let s = &e.symbols[c.sym as usize];
             SymbolMatch {
-                name: s.name.to_string(),
-                kind: s.kind,
-                container: s.container.as_deref().map(str::to_owned),
+                name: syms.name(c.sym).to_string(),
+                kind: syms.kind(c.sym),
+                container: syms.container(c.sym).map(str::to_owned),
                 path: e.path.clone().into(),
                 rel_path: e.rel.to_string(),
-                range: s.range,
+                range: syms.range(c.sym),
                 score,
                 indices,
             }
@@ -541,24 +592,25 @@ pub(crate) fn symbols_named_within(
 ) -> Vec<SymbolMatch> {
     let mask = char_mask(name);
     let within = |e: &FileEntry| roots.is_empty() || roots.iter().any(|root| e.path.starts_with(root));
+    let syms = &data.syms;
     let mut out: Vec<SymbolMatch> = data
         .files
         .iter()
         .flatten()
         .filter(|e| within(e))
         .flat_map(|e| {
-            e.symbols.iter().filter(|s| s.mask == mask && &*s.name == name && kind.is_none_or(|k| s.kind == k)).map(
-                move |s| SymbolMatch {
-                    name: s.name.to_string(),
-                    kind: s.kind,
-                    container: s.container.as_deref().map(str::to_owned),
+            (e.sym_start..e.sym_start + e.sym_len)
+                .filter(|&i| syms.mask(i) == mask && syms.name(i) == name && kind.is_none_or(|k| syms.kind(i) == k))
+                .map(move |i| SymbolMatch {
+                    name: syms.name(i).to_string(),
+                    kind: syms.kind(i),
+                    container: syms.container(i).map(str::to_owned),
                     path: e.path.clone().into(),
                     rel_path: e.rel.to_string(),
-                    range: s.range,
+                    range: syms.range(i),
                     score: 0,
                     indices: Vec::new(),
-                },
-            )
+                })
         })
         .collect();
     out.sort_by(|a, b| a.rel_path.cmp(&b.rel_path).then_with(|| a.range.cmp(&b.range)));

crates/ide-index/src/worker.rs

@@ -173,7 +173,7 @@ impl Shared {
         let root = filter.root().to_owned();
         match store.load() {
             Ok(records) => {
-                let entries: Vec<FileEntry> = records
+                let entries: Vec<(FileEntry, Vec<StoredSymbol>)> = records
                     .into_par_iter()
                     .filter(|(rel, _)| {
                         let path = root.join(rel);
@@ -182,8 +182,8 @@ impl Shared {
                     .map(|(rel, rec)| FileEntry::new(root.join(&rel), rel, rec))
                     .collect();
                 let mut d = self.data.write();
-                for e in entries {
-                    d.insert(e);
+                for (e, symbols) in entries {
+                    d.insert(e, symbols);
                 }
             }
             Err(e) => tracing::warn!("index cache load failed: {e}"),
@@ -321,8 +321,7 @@ impl Shared {
                 match self.extract(f, prev_hash) {
                     Extracted::Unchanged => {
                         // Same content, new mtime: keep the symbols, refresh metadata.
-                        let d = self.data.read();
-                        let mut rec = d.get(&f.path)?.record();
+                        let mut rec = self.data.read().record_of(&f.path)?;
                         rec.mtime = f.mtime;
                         rec.size = f.size;
                         rec.ignored = f.ignored;
@@ -338,11 +337,11 @@ impl Shared {
         let puts: Vec<(String, FileRecord)> =
             extracted.iter().filter_map(|(_, rec, path)| Some((filter.store_key(path)?, rec.clone()))).collect();
         {
-            let entries: Vec<FileEntry> =
+            let entries: Vec<(FileEntry, Vec<StoredSymbol>)> =
                 extracted.into_iter().map(|(rel, rec, path)| FileEntry::new(path, rel, rec)).collect();
             let mut d = self.data.write();
-            for e in entries {
-                d.insert(e);
+            for (e, symbols) in entries {
+                d.insert(e, symbols);
             }
         }
         self.persist(&puts, &[], false);

crates/ide-jsonrpc/src/lib.rs

@@ -223,6 +223,10 @@ pub trait Handler: Send + Sync + 'static {
 
     /// Called once the response to a `method` request is queued: what it sends follows the response.
     fn after_response(&self, _method: &str) {}
+
+    /// Adjusts every message from the peer (responses included) before it is dispatched, e.g.
+    /// to repair values the peer spells more loosely than the types that read them accept.
+    fn normalize_incoming(&self, _message: &mut Value) {}
 }
 
 /// A [`Handler`] that ignores notifications and rejects requests.
@@ -585,9 +589,10 @@ impl Peer {
                 .expect("spawn jsonrpc notification thread");
         }
 
-        // Reader: parses and dispatches; never runs handler code itself.
+        // Reader: parses and dispatches; runs no handler code beyond `normalize_incoming`.
         {
             let inner = inner.clone();
+            let handler = handler.clone();
             tokio::spawn(async move {
                 let mut reader = BufReader::new(reader);
                 let seen_message = AtomicBool::new(false);
@@ -610,7 +615,7 @@ impl Peer {
                     match msg {
                         Ok(Some(body)) => {
                             seen_message.store(true, Ordering::Relaxed);
-                            dispatch(&inner, &notif_tx, &body);
+                            dispatch(&inner, &*handler, &notif_tx, &body);
                         }
                         Ok(None) => break,
                         Err(e) => {
@@ -783,15 +788,16 @@ async fn handle_request(inner: Arc<Inner>, handler: Arc<dyn Handler>, id: Value,
     }
 }
 
-fn dispatch(inner: &Arc<Inner>, notif_tx: &std::sync::mpsc::Sender<Incoming>, body: &[u8]) {
+fn dispatch(inner: &Arc<Inner>, handler: &dyn Handler, notif_tx: &std::sync::mpsc::Sender<Incoming>, body: &[u8]) {
     tracing::trace!(target: "ide_jsonrpc::wire", "<-- {}", String::from_utf8_lossy(body));
-    let msg: Value = match serde_json::from_slice(body) {
+    let mut msg: Value = match serde_json::from_slice(body) {
         Ok(v) => v,
         Err(e) => {
             tracing::warn!("jsonrpc: unparsable message: {e}");
             return;
         }
     };
+    handler.normalize_incoming(&mut msg);
     let Value::Object(mut obj) = msg else {
         tracing::warn!("jsonrpc: ignoring non-object message");
         return;

crates/ide-jsonrpc/src/tests.rs

@@ -541,3 +541,29 @@ async fn output_before_the_handshake_is_reported_not_dropped() {
     assert!(lines.iter().any(|l| l == "python: not found"), "{lines:?}");
     assert!(lines.iter().any(|l| l.ends_with(". . .") && l.len() > 6), "{lines:?}");
 }
+
+#[tokio::test(flavor = "multi_thread")]
+async fn incoming_messages_are_normalized_before_dispatch() {
+    struct Server;
+    impl Handler for Server {
+        fn on_notification(&self, _: &str, _: Value) {}
+        fn on_request(&self, _: &str, params: Value) -> Result<Value, (i64, String)> {
+            Ok(params)
+        }
+    }
+    struct Client;
+    impl Handler for Client {
+        fn on_notification(&self, _: &str, _: Value) {}
+        fn on_request(&self, _: &str, _: Value) -> Result<Value, (i64, String)> {
+            Err((codes::METHOD_NOT_FOUND, "no".into()))
+        }
+        fn normalize_incoming(&self, message: &mut Value) {
+            if let Some(result) = message.get_mut("result") {
+                *result = json!("normalized");
+            }
+        }
+    }
+    let (client, _server) = pair(Arc::new(Client), Arc::new(Server));
+    let v: Value = client.request("echo", "raw", None).await.unwrap();
+    assert_eq!(v, json!("normalized"));
+}

crates/ide-language/src/registry.rs

@@ -79,6 +79,7 @@ const BUILTIN: &[(&str, &str)] = &[
     ("scala", include_str!("../../../languages/scala.toml")),
     ("scss", include_str!("../../../languages/scss.toml")),
     ("shellscript", include_str!("../../../languages/shellscript.toml")),
+    ("slint", include_str!("../../../languages/slint.toml")),
     ("sql", include_str!("../../../languages/sql.toml")),
     ("svelte", include_str!("../../../languages/svelte.toml")),
     ("swift", include_str!("../../../languages/swift.toml")),
@@ -1046,6 +1047,7 @@ mod tests {
             ("icon.svg.import", "godot-resource"),
             ("export_presets.cfg", "godot-resource"),
             ("water.gdshader", "gdshader"),
+            ("app-window.slint", "slint"),
             ("notes.txt", "plaintext"),
         ];
         for (path, id) in cases {

crates/ide-lsp/src/handler.rs

@@ -391,6 +391,10 @@ fn tsserver_ran_out_of_memory(text: &str) -> bool {
 }
 
 impl Handler for ClientHandler {
+    fn normalize_incoming(&self, message: &mut Value) {
+        crate::uri::encode_loose_file_uris(message);
+    }
+
     fn on_notification(&self, method: &str, params: Value) {
         let Some(mgr) = self.mgr.upgrade() else { return };
         match method {

crates/ide-lsp/src/server.rs

@@ -445,8 +445,12 @@ impl Server {
             message.push_str(":\n");
             message.push_str(&tail);
         }
-        let delay = self.record_crash();
-        message.push_str(if delay.is_some() {
+        // Starting the same build again can't help: only an update can.
+        let expired = self.reported_expired_build();
+        let delay = if expired { None } else { self.record_crash() };
+        message.push_str(if expired {
+            "\nThis build has expired; update it to start it again."
+        } else if delay.is_some() {
             "\nRestarting…"
         } else {
             "\nCrashed repeatedly; restart it manually."
@@ -757,6 +761,12 @@ impl Server {
         crash_excerpt(&lines, n)
     }
 
+    /// JetBrains preview builds (kotlin-lsp) refuse to run past their expiry date and
+    /// exit with "This build of kotlin-server has expired".
+    fn reported_expired_build(&self) -> bool {
+        self.stderr.lock().iter().any(|l| is_expired_build_line(l))
+    }
+
     pub fn take_progress(&self) -> Vec<(TaskId, String)> {
         *self.loading.lock() = None;
         self.external_loading.store(0, std::sync::atomic::Ordering::Release);
@@ -911,6 +921,10 @@ fn is_error_headline(line: &str) -> bool {
     named || l.starts_with("Exception in thread") || l.starts_with("thread '") && l.contains("panicked")
 }
 
+fn is_expired_build_line(line: &str) -> bool {
+    line.contains("This build of ") && line.contains(" has expired")
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1071,6 +1085,31 @@ mod tests {
         assert_eq!(waiter.await.unwrap(), (true, ServerStatus::Crashed));
     }
 
+    #[test]
+    fn an_expired_build_is_not_restarted() {
+        let sink: SharedSink = Arc::new(|_: IdeEvent| {});
+        let s = server();
+        let generation = s.begin_start().unwrap();
+        s.push_stderr(generation, "idea.system.path=/tmp/idea-system".into());
+        s.push_stderr(
+            generation,
+            "This build of kotlin-server has expired. The IDE will now close. Please download a new build".into(),
+        );
+        assert_eq!(s.on_closed(generation, &sink, Some(7)), Some(None));
+        assert_eq!(s.status(), ServerStatus::Crashed);
+        assert!(s.status_message().unwrap().ends_with("This build has expired; update it to start it again."));
+        assert!(matches!(s.state.lock().conn, Conn::Failed));
+        // A manual restart (after an update) starts it again.
+        s.reset_for_restart();
+        assert!(s.begin_start().is_some());
+
+        // Any other crash is restarted.
+        let s = server();
+        let generation = s.begin_start().unwrap();
+        s.push_stderr(generation, "Exception in thread main".into());
+        assert_eq!(s.on_closed(generation, &sink, Some(1)), Some(Some(Duration::from_millis(500))));
+    }
+
     #[test]
     fn a_superseded_start_is_not_announced() {
         let s = server();

crates/ide-lsp/src/uri.rs

@@ -1,6 +1,8 @@
 //! `file://` URI ⇄ path conversion (RFC 8089, VS Code-compatible encoding).
 
 use percent_encoding::{AsciiSet, CONTROLS, percent_decode_str, utf8_percent_encode};
+use serde_json::Value;
+use std::borrow::Cow;
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 
@@ -22,6 +24,53 @@ const PATH: &AsciiSet = &CONTROLS
     .add(b'|')
     .add(b'}');
 
+/// What RFC 3986 doesn't allow in a URI and a server may still leave unencoded in a `file:`
+/// URI (non-ASCII is always encoded); `%` stays, it starts the escapes already there.
+const LOOSE: &AsciiSet = &CONTROLS
+    .add(b' ')
+    .add(b'"')
+    .add(b'<')
+    .add(b'>')
+    .add(b'[')
+    .add(b'\\')
+    .add(b']')
+    .add(b'^')
+    .add(b'`')
+    .add(b'{')
+    .add(b'|')
+    .add(b'}');
+
+/// Percent-encodes the characters URIs don't allow in every `file:` URI in `value`, string
+/// values and object keys alike (a workspace edit's `changes`). Eclipse's jdtls sends a path
+/// as is (`file:///H:/项目/…`), which `lsp_types::Uri` rejects, failing the whole response.
+pub fn encode_loose_file_uris(value: &mut Value) {
+    match value {
+        Value::String(s) => {
+            if let Some(encoded) = encode_loose(s) {
+                *s = encoded;
+            }
+        }
+        Value::Array(items) => items.iter_mut().for_each(encode_loose_file_uris),
+        Value::Object(map) => {
+            if map.keys().any(|k| encode_loose(k).is_some()) {
+                *map = std::mem::take(map).into_iter().map(|(k, v)| (encode_loose(&k).unwrap_or(k), v)).collect();
+            }
+            map.values_mut().for_each(encode_loose_file_uris);
+        }
+        _ => {}
+    }
+}
+
+fn encode_loose(s: &str) -> Option<String> {
+    if !s.get(..5).is_some_and(|scheme| scheme.eq_ignore_ascii_case("file:")) {
+        return None;
+    }
+    match Cow::from(utf8_percent_encode(s, LOOSE)) {
+        Cow::Owned(encoded) => Some(encoded),
+        Cow::Borrowed(_) => None,
+    }
+}
+
 pub fn path_to_uri_string(path: &Path) -> String {
     let s = if cfg!(windows) {
         dunce::simplified(path).to_string_lossy().replace('\\', "/")
@@ -95,6 +144,28 @@ pub use ide_core::text::is_virtual_uri;
 mod tests {
     use super::*;
 
+    #[test]
+    fn file_uris_a_server_leaves_unencoded_are_encoded() {
+        // jdtls on a project under a Chinese folder (`java.usages` / references response).
+        let mut v = serde_json::json!({ "result": [{
+            "location": { "uri": "file:///H:/项目/online disk/A.java", "range": { "start": { "line": 1, "character": 2 }, "end": { "line": 1, "character": 3 } } },
+            "kind": "unknown"
+        }], "edit": { "changes": { "file:///tmp/目录/b.java": [] } }, "text": "项目" });
+        let raw = v["result"][0]["location"].clone();
+        assert!(serde_json::from_value::<lsp_types::Location>(raw).is_err(), "lsp-types rejects it as sent");
+        encode_loose_file_uris(&mut v);
+        let uri = v["result"][0]["location"]["uri"].as_str().unwrap();
+        assert_eq!(uri, "file:///H:/%E9%A1%B9%E7%9B%AE/online%20disk/A.java");
+        let location: lsp_types::Location = serde_json::from_value(v["result"][0]["location"].clone()).unwrap();
+        assert!(uri_to_path(location.uri.as_str()).unwrap().ends_with("项目/online disk/A.java"));
+        assert!(v["edit"]["changes"].get("file:///tmp/%E7%9B%AE%E5%BD%95/b.java").is_some());
+        assert_eq!(v["text"], "项目", "only file: URIs change");
+        // Already encoded: untouched.
+        let mut encoded = serde_json::json!("file:///a%20b/%E9%A1%B9.java");
+        encode_loose_file_uris(&mut encoded);
+        assert_eq!(encoded, "file:///a%20b/%E9%A1%B9.java");
+    }
+
     #[cfg(unix)]
     #[test]
     fn round_trip() {

crates/ide-plugin/src/runtime.rs

@@ -55,7 +55,7 @@ use views_bindings::exports::openidea::plugin::view_provider as wit_view;
 use views_bindings::openidea::plugin::view_types as wit_vt;
 
 /// The API version of the world above, `major.minor` of [`host_api`].
-pub const API_VERSION: &str = "1.7";
+pub const API_VERSION: &str = "1.8";
 const EPOCH_TICK: Duration = Duration::from_millis(10);
 pub(crate) const MAX_TEXT: usize = 1 << 20;
 pub(crate) const MAX_TITLE: usize = 256;
@@ -1058,6 +1058,9 @@ fn event_to_wit(e: WorkbenchEvent) -> wit_events::Event {
         }),
         WorkbenchEvent::EditorFocused(p) => wit_events::Event::EditorFocused(p),
         WorkbenchEvent::VcsChanged(p) => wit_events::Event::VcsChanged(p),
+        WorkbenchEvent::ProblemsChanged => {
+            wit_events::Event::Other(wit_types::Extension { kind: "problems-changed".into(), data: "{}".into() })
+        }
         WorkbenchEvent::Scheduled => wit_events::Event::Scheduled,
         WorkbenchEvent::ActionPerformed(a) => wit_events::Event::ActionPerformed(wit_events::ActionPerformed {
             action: a.action,

crates/ide-plugin/src/sandbox.rs

@@ -151,6 +151,67 @@ pub fn resolve_in_roots(roots: &[PathBuf], path: &str) -> Result<PathBuf, String
     }
 }
 
+/// Resolves an already-open document for a background edit without following a
+/// symbolic link, junction, or other Windows reparse point.  Unlike ordinary
+/// project reads, background edits may have originated with another machine:
+/// accepting a link would let that machine change an unexpected file when the
+/// user later saves the editor buffer.
+///
+/// The input is deliberately project-relative.  Existing path components are
+/// examined with `symlink_metadata` from the canonical project root; no
+/// canonicalization happens after the walk, so a link is never traversed.
+pub fn resolve_background_document_in_root(root: &Path, path: &str) -> Result<PathBuf, String> {
+    if path.is_empty() || Path::new(path).is_absolute() {
+        return Err(format!("{path}: background document paths must be project-relative"));
+    }
+    let root = dunce::canonicalize(root).map_err(|e| format!("project root unavailable: {e}"))?;
+    let components: Vec<_> = Path::new(path).components().collect();
+    if components.is_empty() || components.iter().any(|part| !matches!(part, std::path::Component::Normal(_))) {
+        return Err(format!("{path}: background document paths must not leave the project"));
+    }
+    let mut current = root.clone();
+    for (index, part) in components.iter().enumerate() {
+        let std::path::Component::Normal(name) = part else { unreachable!() };
+        if background_control_name(name) {
+            return Err(format!("{path}: background edits may not target VCS or IDE control files"));
+        }
+        current.push(name);
+        let metadata = std::fs::symlink_metadata(&current).map_err(|_| format!("{path}: no such open document"))?;
+        if is_link_or_reparse(&metadata) {
+            return Err(format!("{path}: background edits refuse symbolic links"));
+        }
+        if index + 1 < components.len() && !metadata.is_dir() {
+            return Err(format!("{path}: not a directory"));
+        }
+        if index + 1 == components.len() && !metadata.is_file() {
+            return Err(format!("{path}: not a file"));
+        }
+    }
+    Ok(current)
+}
+
+/// [`resolve_background_document_in_root`] over a workspace group's roots.
+pub fn resolve_background_document_in_roots(roots: &[PathBuf], path: &str) -> Result<PathBuf, String> {
+    first_root_resolving(roots, path, resolve_background_document_in_root)
+}
+
+fn is_link_or_reparse(metadata: &std::fs::Metadata) -> bool {
+    #[cfg(windows)]
+    let reparse = {
+        use std::os::windows::fs::MetadataExt;
+        metadata.file_attributes() & 0x400 != 0 // FILE_ATTRIBUTE_REPARSE_POINT
+    };
+    #[cfg(not(windows))]
+    let reparse = false;
+    metadata.file_type().is_symlink() || reparse
+}
+
+fn background_control_name(name: &std::ffi::OsStr) -> bool {
+    let name = name.to_string_lossy();
+    let name = name.split(':').next().unwrap_or_default().trim_end_matches(['.', ' ']);
+    matches!(name.to_ascii_lowercase().as_str(), ".git" | ".hg" | ".svn" | ".idea" | ".openidea" | ".vscode")
+}
+
 /// Whether `path` (absolute, or relative to `root`) lands inside `root`,
 /// without requiring it to exist: `Ok(true)` also for a missing path, so
 /// callers distinguish "outside" from "absent". Existing symlinks are
@@ -705,6 +766,25 @@ mod tests {
         assert!(!names_git_dir(Path::new(".github/workflows/ci.yml")));
     }
 
+    #[test]
+    fn background_document_edits_are_relative_and_exclude_control_directories() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path().join("proj");
+        std::fs::create_dir_all(root.join("src")).unwrap();
+        std::fs::create_dir_all(root.join(".git/hooks")).unwrap();
+        std::fs::create_dir_all(root.join(".openidea")).unwrap();
+        std::fs::write(root.join("src/main.rs"), "fn main() {}\n").unwrap();
+        std::fs::write(root.join(".git/hooks/pre-commit"), "#!/bin/sh\n").unwrap();
+        std::fs::write(root.join(".openidea/state"), "state\n").unwrap();
+
+        assert!(resolve_background_document_in_root(&root, "src/main.rs").is_ok());
+        for path in
+            ["/etc/passwd", "../outside", "src/../.git/hooks/pre-commit", ".git/hooks/pre-commit", ".openidea/state"]
+        {
+            assert!(resolve_background_document_in_root(&root, path).is_err(), "{path}");
+        }
+    }
+
     #[test]
     fn git_folder_is_recognised_under_every_spelling_that_opens_it() {
         for path in [
@@ -740,6 +820,23 @@ mod tests {
         assert!(resolve_new_in_root(&root, "out/x.txt").unwrap_err().contains("outside"));
     }
 
+    #[cfg(unix)]
+    #[test]
+    fn background_document_edits_refuse_final_and_ancestor_symlinks() {
+        use std::os::unix::fs::symlink;
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path().join("proj");
+        std::fs::create_dir_all(root.join("src")).unwrap();
+        std::fs::write(root.join("src/main.rs"), "fn main() {}\n").unwrap();
+        symlink(root.join("src/main.rs"), root.join("final-link.rs")).unwrap();
+        symlink(root.join("src"), root.join("linked-src")).unwrap();
+
+        assert!(resolve_background_document_in_root(&root, "final-link.rs").unwrap_err().contains("symbolic links"));
+        assert!(
+            resolve_background_document_in_root(&root, "linked-src/main.rs").unwrap_err().contains("symbolic links")
+        );
+    }
+
     #[cfg(unix)]
     #[test]
     fn writable_paths_follow_existing_and_dangling_symlinks() {

crates/ide-plugin/src/types.rs

@@ -119,11 +119,13 @@ pub enum EventKind {
     EditorFocused,
     ActionPerformed,
     VcsChanged,
+    /// Problems of the window's files changed (a language server or a report).
+    ProblemsChanged,
     Scheduled,
 }
 
 impl EventKind {
-    pub const ALL: [Self; 16] = [
+    pub const ALL: [Self; 17] = [
         Self::DocumentChanged,
         Self::WebsocketReady,
         Self::FileClosed,
@@ -139,6 +141,7 @@ impl EventKind {
         Self::EditorFocused,
         Self::ActionPerformed,
         Self::VcsChanged,
+        Self::ProblemsChanged,
         Self::Scheduled,
     ];
 
@@ -159,6 +162,7 @@ impl EventKind {
             Self::EditorFocused => "editor-focused",
             Self::ActionPerformed => "action-performed",
             Self::VcsChanged => "vcs-changed",
+            Self::ProblemsChanged => "problems-changed",
             Self::Scheduled => "scheduled",
         }
     }
@@ -294,6 +298,8 @@ pub enum WorkbenchEvent {
     EditorFocused(Option<String>),
     ActionPerformed(ActionPerformed),
     VcsChanged(String),
+    /// Problems of the window's files changed; plugins re-read `problems`.
+    ProblemsChanged,
     Scheduled,
 }
 
@@ -315,6 +321,7 @@ impl WorkbenchEvent {
             Self::EditorFocused(_) => EventKind::EditorFocused,
             Self::ActionPerformed(_) => EventKind::ActionPerformed,
             Self::VcsChanged(_) => EventKind::VcsChanged,
+            Self::ProblemsChanged => EventKind::ProblemsChanged,
             Self::Scheduled => EventKind::Scheduled,
         }
     }

crates/ide-plugin/src/wit_host.rs

@@ -870,7 +870,7 @@ impl editor::Host for StoreData {
             return Ok(Err(wit::Error::Invalid("edits too large".into())));
         }
         let root = self.table.get(&project)?.root.clone();
-        let path = match self.resolve_in_project(&root, &path) {
+        let path = match self.resolve_background_document_in_project(&root, &path) {
             Ok(path) => path,
             Err(error) => return Ok(Err(wit::Error::Invalid(error))),
         };
@@ -936,6 +936,14 @@ impl StoreData {
             sandbox::resolve_writable_in_roots(&self.host.member_roots(root), path).map_err(|_| root_error)
         })
     }
+    /// A background document edit is the only plugin operation that changes an
+    /// editor on behalf of a remote peer.  It therefore rejects links and IDE
+    /// control directories instead of using the normal read resolver.
+    fn resolve_background_document_in_project(&self, root: &Path, path: &str) -> Result<PathBuf, String> {
+        sandbox::resolve_background_document_in_root(root, path).or_else(|root_error| {
+            sandbox::resolve_background_document_in_roots(&self.host.member_roots(root), path).map_err(|_| root_error)
+        })
+    }
     /// Whether a `project` resource's path lands inside the resource's root or
     /// any member of its workspace group, without requiring it to exist.
     fn inside_project(&self, root: &Path, path: &str) -> Result<bool, String> {

crates/ide-plugin/tests/api_compat.rs

@@ -91,15 +91,15 @@ fn the_sdk_carries_the_hosts_wit() {
 
 #[test]
 fn the_version_check_runs_compatible_components_and_explains_the_rest() {
-    let host = v("1.7.0");
-    for ok in ["1.0.0", "1.3.0", "1.4.7", "1.5.0", "1.6.0", "1.7.0", "1.0.0-rc.1"] {
+    let host = v("1.8.0");
+    for ok in ["1.0.0", "1.3.0", "1.4.7", "1.5.0", "1.6.0", "1.7.0", "1.8.0", "1.0.0-rc.1"] {
         assert_eq!(check_api(&v(ok), &host), Ok(()), "{ok}");
     }
-    let newer = check_api(&v("1.8.0"), &host).unwrap_err();
-    assert!(newer.contains("1.8") && newer.contains("update OpenIDEA"), "{newer}");
+    let newer = check_api(&v("1.9.0"), &host).unwrap_err();
+    assert!(newer.contains("1.9") && 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 1.7 SDK"), "{older}");
+    assert!(older.contains("rebuild it with the 1.8 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());

crates/ide-plugin/tests/fixtures/api14/dist/plugin.wasm.sources

@@ -1 +1 @@
-d6c855f1f91aeb02eec5d6c8a07be4eb64bae0704619f44cb67f3b832daf01ee
+6c50332c868a890b91a7f92ef7f92e76a4818b7435291e99c77c0b9f0931b81c

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

@@ -1 +1 @@
-51d00702c42c7167083caea70cf2df022e512bcaf89af8addf526421ff45a15f
+fdcb208365db90bcd06d0d0df3d436b69d1229c40f7c63dd6f1ab768e0d236b8

crates/ide-plugin/tests/fixtures/data-tools/dist/plugin.wasm.sources

@@ -1 +1 @@
-40d2fd76ba96b0c93ea0a034c6749709ddc00fc119046e653a50b180a9c4718d
+3108abe8d381b224ec4b44ecf4c43c045671bd5e221ee21582e25497f8c14dff

crates/ide-plugin/tests/fixtures/detail-views/dist/plugin.wasm.sources

@@ -1 +1 @@
-08822287f3649412340f9dbbe2f0ea5a5cd2f543a3c242c5d0a29c422c4c5367
+876a84b7da5a4b27fce47cf71a4dc28eb1ea6c9d54283c1b73a2ae2411653bf5

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

@@ -1 +1 @@
-43eba23cc14cf3c74bfc934099cd58df20f07ee5df96cc10100b90016c544a7a
+234dc693e01e484b91fa7f2d0ac0e7757fb69c9fba81f06bf8ef1cd3624228d8

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

@@ -21,6 +21,31 @@ impl Plugin for Fixture {
                 &[Diagnostic::new(Range::default(), Severity::Info, "Manual problem")],
             )
             .map(|()| None),
+            // The host-owned snapshot, one entry per producer: what `problems` reads.
+            "problems" => {
+                let files: Vec<String> = host::problems(None)?
+                    .into_iter()
+                    .map(|f| format!("{}:{}:{}", f.path, f.source, f.diagnostics.len()))
+                    .collect();
+                Ok(Some(files.join("|")))
+            }
+            // A line-end annotation in the severity styles the editor draws: the host must
+            // keep `typo` and `weak` instead of dropping them as unknown.
+            "decorate" => {
+                let path = arg.unwrap_or_default();
+                let item = |style: &str, after: &str| openidea_plugin::Decoration {
+                    range: Range::default(),
+                    style: style.into(),
+                    hover: None,
+                    after: Some(after.into()),
+                };
+                host::set_decorations(
+                    path,
+                    "fixture",
+                    &[item("typo", "typo message"), item("weak", "weak message")],
+                )
+                .map(|()| None)
+            }
             _ => Err(Error::NotFound(id.into())),
         }
     }

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

@@ -1 +1 @@
-520d9a95328dc772bbb913a2e5e22af8243c95ca45744cbb65b25747653d2a34
+927c329fd21d12fd5f423b937e1be756be45a4c6dceee08679e762d5d9f511f2

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

@@ -1 +1 @@
-acd3d0ee3f886c6a271ce3139200ce5bdb46e40f9c68e495c5ff9b4db98a88ac
+e7c77fde915e0765f91929dba2aa8eff606f2302e078b7305d272a4de5b9d80b

crates/ide-plugin/tests/fixtures/ext-owner/dist/plugin.wasm.sources

@@ -1 +1 @@
-0cf3bc2197f0bd5339fe3c2199bd973e68b3637b8c5ae07902e62659160275e3
+3feb9df8b408dedbc3586864db00b92c8cb244c8ad5b8f10c95edb8eb3d30df1

crates/ide-plugin/tests/fixtures/file-templates/dist/plugin.wasm.sources

@@ -1 +1 @@
-17f837c8d6f58800728e00060afe68b2a093085d816d809c9e67065fdd165352
+3bfce29f90b9d2f20082b9bdd0957c6c58c265a346305ec948f514537a4579c8

crates/ide-plugin/tests/fixtures/files-events/dist/plugin.wasm.sources

@@ -1 +1 @@
-2cca80220fab6764a8e1f51db8ed2f55b603000c8d0dbf5913a441876b7857ba
+ca72c5cfa2f76a93bc07495d50e58181a9c6c2fc75854cf548bb0278814ddb87

crates/ide-plugin/tests/fixtures/grouped-views/dist/plugin.wasm.sources

@@ -1 +1 @@
-54211437002ad83a9d3d642f2dca5f37cadd89d7d77ddc7de545db87b99fb8b7
+8a4a7df8fd6cf397750ac24cedf06174ed50e4214ef44029e29f7d0557d426ba

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

@@ -1 +1 @@
-4326d9cdefe71f4bb9aab043ccef883abbd13145b1579352b97c66889f514c68
+8d12313675e0869e087ac4c79bdfb1a9738867e28af2437eff27cb07254f572b

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

@@ -1 +1 @@
-2469023f4f29b9abdaa27c9d96774229c4dd002366421dc508926c3fed1fba1b
+1b2ad52d4cbb4abb662be5772f050844836f8e3f0c525edd0de19ff45e95a148

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

@@ -1 +1 @@
-233461ab52a12e27fa600e108e83cab1b930b3e61812e0c048c99c1e18c6d646
+13babf73d8d3d029aba26641b01a4add3abb3dab84394d8bd676edb064dc0c19

crates/ide-plugin/tests/fixtures/inlay-hints/dist/plugin.wasm.sources

@@ -1 +1 @@
-bfc654523da608bbc008ea6a15a0cfd0b129ffab70088bf6b610786b63b5352e
+a7790bf28783d57ed47f635a58981b80ddaecd7074cf88c539465b57132a9f8f

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

@@ -1 +1 @@
-c8536be072d27aa89f5e92b5b96e38ed65b7f06c35c05ecbd4a151218203c5f7
+af7070f6ca3a14cf480260aa21b7a6e95038996d224d40e53a487c96a8f3acf2

crates/ide-plugin/tests/fixtures/language-features/dist/plugin.wasm.sources

@@ -1 +1 @@
-7c0c1f5035e12c794d48cb75a8fc259d11dd99ba3188030fe1d9956720ee6ad5
+16930ecfe74d096e6dcaa5fbf35664128b4d3844f47993a947aabe9d2a9650de

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

@@ -1 +1 @@
-3cf5fd6ab0ce909b806230e20a7fa46264f85937018cfa68865ec0eeb92d4b72
+25eaf7ac2837ade4b3204698d3af41854324ece6ec196daba84bea6bb41f6cde

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

@@ -5,9 +5,9 @@ wit_bindgen::generate!({
     inline: "
         package fixture:misbehave;
         world misbehave {
-            include openidea:plugin/plugin-syntax@1.7.0;
-            export openidea:plugin/providers@1.7.0;
-            export openidea:plugin/file-actions@1.7.0;
+            include openidea:plugin/plugin-syntax@1.8.0;
+            export openidea:plugin/providers@1.8.0;
+            export openidea:plugin/file-actions@1.8.0;
         }
     ",
     path: "../../../../../wit",

crates/ide-plugin/tests/fixtures/path-events/dist/plugin.wasm.sources

@@ -1 +1 @@
-d349977fd3cbfba92d1d953ac09f65dae5b83b7070723b59553d791c638acf81
+f7cd477be706ee5da2656ffb5435cb2b52443aec1270b3b1d804b2bdc6ed8bc8

crates/ide-plugin/tests/fixtures/private-dir/dist/plugin.wasm.sources

@@ -1 +1 @@
-e796039ae2f8e534ffc8c2ed2e47e910aaf593c464525287699cf1daf3e195ef
+c97989134a8e8a0a12013909f4726288b6d9cdaa44d02a58ff505a6cbb1fb9a1

crates/ide-plugin/tests/fixtures/semantic-tokens/dist/plugin.wasm.sources

@@ -1 +1 @@
-5e084fa409bb0641409110d91f203a6f99b451b95cd8067bd1ee68140bf8a892
+67660f5ebbfdd3967fabcc0b5c41f215d4a38d9092b91eb0166f12bccfdffffa

crates/ide-plugin/tests/fixtures/settings-pages/dist/plugin.wasm.sources

@@ -1 +1 @@
-521557c1a062a9b82afa14547bc54b57255cdbed3b2ab4b1b86424dfb8accbdc
+09c810ce7ebd820ea21525dc9faea99b13e7665b308cb131510e02b86e763c9f

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

@@ -1 +1 @@
-5280990269e944aef81ec91b356fadf4aa2fc7e7bb10e4b6842e1dc1c669704a
+9b3a210440560e05326947c7d549ce691315839daea2931c6a78720f7b0d9e7c

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

@@ -1 +1 @@
-ff1391d3c9338b6270fef8af7d7c4a5bc595c391997c220a3a827b4b8a068de8
+57d8b00b5853ca789fe704f21e4394d1524dd73dfd27ea4a0b34f4b0e4f1a5f8

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

@@ -1 +1 @@
-b78ac0b6fa14401a6379f3e6d07d1398a63d70e882930b3747ec843c0fdb5de7
+53e355922819b8034c93070323c7eb2b1505d3bf561dd5de6abb930fe514748c

crates/ide-plugin/tests/fixtures/web-content/dist/plugin.wasm.sources

@@ -1 +1 @@
-55331477c1d5322b0dc35d13fc7f8223bf697f5f21328d340f75519dd1098727
+7af929a1adf5d89929d66e78068253ccde9ad5cedee329c2d4db6b7a5e29790e

crates/ide-plugin/tests/fixtures/web-log/dist/plugin.wasm.sources

@@ -1 +1 @@
-0ae6b7edd0d7cd5025ead4a4afacf0fbe3ebc9548d847f94be0e63585a19747e
+511fab979382c5d64054ba4f5fdfc98d50e252dfd5896265ee589336bf8e7d70

crates/ide-plugin/tests/fixtures/web-pty/dist/plugin.wasm.sources

@@ -1 +1 @@
-5d909d6ab2e73fabba2d213a944546ef7e425552852cf7f74e00eb94c9d167ac
+444497128ec5e1e01229a93d2340b49ccc5bc27e67defb2c4fe19683042442a3

crates/ide-run/src/detect.rs

@@ -53,6 +53,8 @@ pub(crate) fn detect_with_profiles(
         &mut out,
     );
     detect_projects_matching(root, ruby_project, detect_ruby, &mut out);
+    detect_projects(root, &["rebar.config"], detect_rebar, &mut out);
+    detect_projects(root, &["mix.exs"], detect_mix, &mut out);
     for dir in ide_core::project_roots::discover(root, &["CMakeLists.txt"]) {
         let start = out.len();
         cmake::detect(&dir, if dir == root { profiles } else { None }, &mut out);
@@ -1326,6 +1328,38 @@ pub(crate) fn just_recipes(src: &str) -> Vec<String> {
 
 // ---------------------------------------------------------------- godot
 
+// ---------------------------------------------------------------- rebar3 / mix
+
+/// rebar3 (Erlang): the shell with the applications started, the EUnit tests and, with
+/// `*_SUITE.erl` suites, Common Test. A `rebar3` script in the project wins over the PATH.
+fn detect_rebar(root: &Path, out: &mut Vec<RunConfig>) {
+    let rebar = wrapper(root, "rebar3", "rebar3.cmd", "rebar3");
+    out.push(config("rebar3:shell", "rebar3 shell", "rebar3", &rebar, &["shell"]));
+    out.push(config("rebar3:eunit", "rebar3 eunit", "rebar3", &rebar, &["eunit"]).test());
+    let suites = |dir: &Path| {
+        fs::read_dir(dir)
+            .into_iter()
+            .flatten()
+            .flatten()
+            .any(|e| e.file_name().to_string_lossy().ends_with("_SUITE.erl"))
+    };
+    let mut apps = subdirs(&root.join("apps")).into_iter().chain(subdirs(&root.join("lib")));
+    if suites(&root.join("test")) || apps.any(|app| suites(&app.join("test"))) {
+        out.push(config("rebar3:ct", "rebar3 ct", "rebar3", &rebar, &["ct"]).test());
+    }
+}
+
+/// Mix (Elixir): the application in IEx (`phx.server` for Phoenix) and its ExUnit tests.
+fn detect_mix(root: &Path, out: &mut Vec<RunConfig>) {
+    let phoenix = read(&root.join("mix.exs")).is_some_and(|src| src.contains("{:phoenix,"));
+    if phoenix {
+        out.push(config("mix:phx.server", "iex -S mix phx.server", "mix", "iex", &["-S", "mix", "phx.server"]));
+    } else {
+        out.push(config("mix:iex", "iex -S mix", "mix", "iex", &["-S", "mix"]));
+    }
+    out.push(config("mix:test", "mix test", "mix", "mix", &["test"]).test());
+}
+
 /// Godot projects (`project.godot`) at the root or one level down: "Godot Project"
 /// runs the main scene (`godot --path .`), debuggable through the editor's adapter.
 fn detect_godot(root: &Path, out: &mut Vec<RunConfig>) {

crates/ide-run/tests/detect.rs

@@ -1173,3 +1173,36 @@ fn a_django_project_in_src_uses_the_environment_next_to_it() {
     assert!(c.iter().any(|c| c.id == "pytest"));
     assert!(!c.iter().any(|c| c.id.starts_with("pytest:")), "{:?}", c.iter().map(|c| &c.id).collect::<Vec<_>>());
 }
+
+#[test]
+fn rebar3_projects() {
+    let dir = project(&[("rebar.config", "{erl_opts, [debug_info]}.\n"), ("src/app.erl", "-module(app).\n")]);
+    let c = detect(dir.path());
+    assert_eq!(ids(&c), ["rebar3:shell", "rebar3:eunit"]);
+    assert_eq!(cmdline(&c[0]), "rebar3 shell");
+    assert!(c[1].is_test);
+
+    // Common Test suites in an umbrella app; the project's own rebar3 script.
+    let dir = project(&[
+        ("rebar.config", ""),
+        ("rebar3", "#!/usr/bin/env escript\n"),
+        ("apps/core/test/core_SUITE.erl", "-module(core_SUITE).\n"),
+    ]);
+    let c = detect(dir.path());
+    assert_eq!(ids(&c), ["rebar3:shell", "rebar3:eunit", "rebar3:ct"]);
+    if !cfg!(windows) {
+        assert_eq!(cmdline(find(&c, "rebar3:ct")), "./rebar3 ct");
+    }
+}
+
+#[test]
+fn mix_projects() {
+    let dir = project(&[("mix.exs", "defmodule App.MixProject do\n  defp deps, do: []\nend\n")]);
+    let c = detect(dir.path());
+    assert_eq!(ids(&c), ["mix:iex", "mix:test"]);
+    assert_eq!(cmdline(&c[0]), "iex -S mix");
+    assert!(c[1].is_test);
+
+    let dir = project(&[("mix.exs", "defp deps do\n  [{:phoenix, \"~> 1.7\"}]\nend\n")]);
+    assert_eq!(cmdline(&detect(dir.path())[0]), "iex -S mix phx.server");
+}

crates/ide-sdk/src/apply.rs

@@ -3,7 +3,7 @@
 
 use crate::discover::{project_venv_python, workspace_tsdk};
 use crate::exec::{path_with, search_path, which};
-use crate::npm::{has_ts_api, own_typescript};
+use crate::npm::{has_ts_api, native_typescript, own_typescript};
 use crate::{angular, astro, godot, pinned, vue};
 use crate::{bin_dir, exe, venv_of};
 use ide_core::settings::{InspectionLevel, InspectionSettings, LanguageServerSettings, Settings};
@@ -722,6 +722,16 @@ pub fn tsdk(root: &Path, s: &Settings) -> Option<PathBuf> {
     }
 }
 
+/// TypeScript 7's native executable when the selected TypeScript is one (see
+/// [`native_typescript`]); `None` for the bundled one and TypeScript 6 and older.
+pub fn native_tsdk(root: &Path, s: &Settings) -> Option<PathBuf> {
+    match s.languages.typescript.version.trim() {
+        "" | "bundled" => None,
+        "workspace" => native_typescript(&root.join("node_modules/typescript")),
+        custom => native_typescript(&setting_path(root, custom)?),
+    }
+}
+
 const PYTHON_SERVERS: [&str; 7] = ["basedpyright", "pyright", "ty", "pyrefly", "pylsp", "jedi-language-server", "ruff"];
 
 pub(crate) fn merge(base: &mut Value, layer: Value) {
@@ -957,10 +967,15 @@ pub fn resolve_run_command(config: &mut RunConfig, root: &Path, s: &Settings) {
 }
 
 pub fn configure_server(cfg: &mut LanguageServerConfig, root: &Path, server_root: &Path, s: &Settings) {
+    let mut path_dirs: Vec<PathBuf> = Vec::new();
     if let Some(custom) = tool_command(root, s, &cfg.command) {
+        // An executable chosen from a Node.js installation (`~/.nvm/versions/node/v26/bin/tsc`,
+        // its `npx`) runs on that Node: its `#!/usr/bin/env node` finds the `node` beside it.
+        if let Some(bin) = custom.parent().filter(|bin| bin.join(exe("node")).is_file()) {
+            path_dirs.push(bin.to_path_buf());
+        }
         cfg.command = custom.to_string_lossy().into_owned();
     }
-    let mut path_dirs: Vec<PathBuf> = Vec::new();
     let name = cfg.name.clone();
     let name = name.as_str();
 
@@ -1135,6 +1150,16 @@ pub fn configure_server(cfg: &mut LanguageServerConfig, root: &Path, server_root
             _ => {}
         }
     }
+    // TypeScript 7 serves LSP itself: it replaces the tsserver-based server.
+    if matches!(name, "vtsls" | "typescript-language-server")
+        && let Some(native) = native_tsdk(server_root, s).or_else(|| native_tsdk(root, s))
+    {
+        cfg.command = native.to_string_lossy().into_owned();
+        cfg.args = vec!["--lsp".into(), "--stdio".into()];
+        cfg.initialization_options = None;
+        cfg.tsserver_project = false;
+        return;
+    }
     let vue_command = s.tool_path(vue::SERVER).and_then(|p| setting_path(root, p));
     let vue_command = vue_command.as_deref().map_or(vue::SERVER.into(), Path::to_string_lossy);
     if name == "vtsls"

crates/ide-sdk/src/discover.rs

@@ -749,14 +749,26 @@ pub(crate) fn workspace_tsdk(root: &Path) -> Option<PathBuf> {
 
 fn typescript(root: Option<&Path>) -> Vec<Sdk> {
     let mut out = Vec::new();
-    if let Some(lib) = root.and_then(workspace_tsdk) {
+    // TypeScript 7 has no `tsserver.js`; its package directory stands for it (`native_tsdk`).
+    let native = || {
+        let package = root?.join("node_modules/typescript");
+        crate::npm::native_typescript(&package).map(|_| package.join("lib"))
+    };
+    if let Some(lib) = root.and_then(workspace_tsdk).or_else(native) {
         let version = std::fs::read_to_string(lib.parent().unwrap_or(&lib).join("package.json"))
             .ok()
             .and_then(|t| serde_json::from_str::<serde_json::Value>(&t).ok())
             .and_then(|v| v.get("version").and_then(|v| v.as_str()).map(str::to_owned));
         out.push(Sdk {
             path: lib.clone().into(),
-            name: format!("TypeScript {}", version.clone().unwrap_or_default()).trim().to_owned(),
+            name: format!(
+                "TypeScript {}{}",
+                version.clone().unwrap_or_default(),
+                if crate::npm::has_ts_api(&lib) { "" } else { " (native)" }
+            )
+            .replace("  ", " ")
+            .trim()
+            .to_owned(),
             version,
             source: "workspace".into(),
             home: lib.parent().map(Into::into),

crates/ide-sdk/src/npm.rs

@@ -10,6 +10,41 @@ pub(crate) fn has_ts_api(lib: &Path) -> bool {
     lib.join("typescript.js").is_file()
 }
 
+/// The native executable of TypeScript 7 (`typescript` 7+, whose `tsc` is native, or
+/// `@typescript/native-preview`'s `tsgo`), from its package directory or its `lib`.
+/// These packages have no JavaScript API (`lib/typescript.js`); their platform package
+/// (`@typescript/typescript-darwin-arm64`) holds the executable, which serves LSP itself
+/// (`--lsp --stdio`).
+pub(crate) fn native_typescript(dir: &Path) -> Option<PathBuf> {
+    let package = if dir.join("package.json").is_file() { dir } else { dir.parent()? };
+    if has_ts_api(&package.join("lib")) {
+        return None;
+    }
+    let manifest: serde_json::Value =
+        serde_json::from_slice(&std::fs::read(package.join("package.json")).ok()?).ok()?;
+    let (base, bin) = match manifest.get("name")?.as_str()? {
+        "typescript" => ("typescript", "tsc"),
+        "@typescript/native-preview" => ("native-preview", "tsgo"),
+        _ => return None,
+    };
+    let os = match std::env::consts::OS {
+        "macos" => "darwin",
+        "windows" => "win32",
+        os => os,
+    };
+    let arch = match std::env::consts::ARCH {
+        "aarch64" => "arm64",
+        "x86_64" => "x64",
+        arch => arch,
+    };
+    let platform = format!("{base}-{os}-{arch}");
+    // Next to the package (`node_modules/@typescript/…`) or nested in it.
+    package
+        .ancestors()
+        .map(|a| a.join("node_modules/@typescript").join(&platform).join("lib").join(crate::exe(bin)))
+        .find(|exe| exe.is_file())
+}
+
 /// The usable TypeScript library Node resolves from an installed server package.
 pub(crate) fn own_typescript(package: &Path) -> Option<PathBuf> {
     package.ancestors().map(|a| a.join("node_modules/typescript/lib")).find(|l| has_ts_api(l))

crates/ide-sdk/src/tests.rs

@@ -1325,6 +1325,85 @@ fn custom_tool_path_replaces_the_command() {
     assert_eq!(cfg.command, "zls");
 }
 
+/// A server picked from a Node.js installation (nvm's `bin/tsc`, `bin/npx`) is a
+/// `#!/usr/bin/env node` script: it runs on that installation's Node, ahead of the
+/// project's Node.js interpreter.
+#[test]
+fn a_server_chosen_from_a_node_installation_runs_on_that_node() {
+    let tmp = tempfile::tempdir().unwrap();
+    let v26 = tmp.path().join("nvm/versions/node/v26.4.0/bin");
+    let v20 = tmp.path().join("node20/bin");
+    for dir in [&v26, &v20] {
+        std::fs::create_dir_all(dir).unwrap();
+        std::fs::write(dir.join(exe("node")), "").unwrap();
+    }
+    std::fs::write(v26.join("tsc"), "#!/usr/bin/env node\n").unwrap();
+    let mut s = Settings::default();
+    s.languages.node.interpreter = v20.join(exe("node")).to_string_lossy().into_owned();
+    s.tools.insert(
+        "typescript-language-server".into(),
+        ide_core::settings::ToolSettings { path: v26.join("tsc").to_string_lossy().into_owned() },
+    );
+    let mut cfg = server("typescript-language-server");
+    configure_server(&mut cfg, tmp.path(), tmp.path(), &s);
+    let path: Vec<std::path::PathBuf> = std::env::split_paths(&cfg.env["PATH"]).collect();
+    assert_eq!(path[..2], [v26.clone(), v20.clone()]);
+
+    // Elsewhere, the project's Node.js interpreter comes first.
+    s.tools.insert(
+        "typescript-language-server".into(),
+        ide_core::settings::ToolSettings { path: tmp.path().join("tools/tsc").to_string_lossy().into_owned() },
+    );
+    let mut cfg = server("typescript-language-server");
+    configure_server(&mut cfg, tmp.path(), tmp.path(), &s);
+    assert_eq!(std::env::split_paths(&cfg.env["PATH"]).next(), Some(v20));
+}
+
+/// TypeScript 7 (`typescript` 7+, `@typescript/native-preview`) has no tsserver: choosing it
+/// runs its native executable's own language server instead of vtsls / typescript-language-server.
+#[test]
+fn typescript_7_runs_its_own_language_server() {
+    let tmp = tempfile::tempdir().unwrap();
+    let modules = tmp.path().join("node_modules");
+    let os = match std::env::consts::OS {
+        "macos" => "darwin",
+        "windows" => "win32",
+        os => os,
+    };
+    let arch = match std::env::consts::ARCH {
+        "aarch64" => "arm64",
+        "x86_64" => "x64",
+        arch => arch,
+    };
+    std::fs::create_dir_all(modules.join("typescript/lib")).unwrap();
+    std::fs::write(modules.join("typescript/package.json"), r#"{"name":"typescript","version":"7.0.2"}"#).unwrap();
+    let native = modules.join(format!("@typescript/typescript-{os}-{arch}/lib")).join(exe("tsc"));
+    std::fs::create_dir_all(native.parent().unwrap()).unwrap();
+    std::fs::write(&native, "").unwrap();
+    let mut s = Settings::default();
+    s.languages.typescript.version = "workspace".into();
+    for name in ["vtsls", "typescript-language-server"] {
+        let mut cfg = server(name);
+        configure_server(&mut cfg, tmp.path(), tmp.path(), &s);
+        assert_eq!(Path::new(&cfg.command), native, "{name}");
+        assert_eq!(cfg.args, ["--lsp", "--stdio"]);
+        assert!(cfg.initialization_options.is_none());
+    }
+    // Picked as a directory (its `lib`, as for older versions), too.
+    s.languages.typescript.version = modules.join("typescript/lib").to_string_lossy().into_owned();
+    let mut cfg = server("vtsls");
+    configure_server(&mut cfg, tmp.path(), tmp.path(), &s);
+    assert_eq!(Path::new(&cfg.command), native);
+
+    // TypeScript 6 keeps the tsserver-based server, pointed at it.
+    std::fs::write(modules.join("typescript/lib/typescript.js"), "").unwrap();
+    std::fs::write(modules.join("typescript/lib/tsserver.js"), "").unwrap();
+    s.languages.typescript.version = "workspace".into();
+    let mut cfg = server("vtsls");
+    configure_server(&mut cfg, tmp.path(), tmp.path(), &s);
+    assert_eq!(cfg.command, "vtsls");
+}
+
 #[test]
 fn the_godot_setting_applies_to_server_debugger_and_run_configurations() {
     let tmp = tempfile::tempdir().unwrap();

crates/ide-search/benches/search.rs

@@ -65,5 +65,26 @@ fn bench(c: &mut Criterion) {
     g.finish();
 }
 
-criterion_group!(benches, bench);
+// No .ignore file: the query's subtree masks must prevent traversal themselves.
+fn excluded_subtrees(c: &mut Criterion) {
+    let dir = tempfile::tempdir().unwrap();
+    for module in 0..100 {
+        let root = dir.path().join(format!("modules/m{module}"));
+        std::fs::create_dir_all(root.join("src")).unwrap();
+        std::fs::write(root.join("src/main.go"), "needle").unwrap();
+        for dependency in 0..50 {
+            let dep = root.join(format!("node_modules/dep{dependency}/lib"));
+            std::fs::create_dir_all(&dep).unwrap();
+            std::fs::write(dep.join("index.js"), "needle").unwrap();
+        }
+    }
+    let q = SearchQuery { exclude: vec!["**/node_modules/**".into()], ..query("needle", false) };
+    assert_eq!(run(dir.path(), &q), 100);
+    let mut group = c.benchmark_group("search_excluded_subtrees");
+    group.sample_size(15);
+    group.bench_function("5k_dependencies", |b| b.iter(|| black_box(run(dir.path(), &q))));
+    group.finish();
+}
+
+criterion_group!(benches, bench, excluded_subtrees);
 criterion_main!(benches);

crates/ide-search/src/engine.rs

@@ -143,18 +143,22 @@ pub(crate) fn run(req: Request<'_>) -> IdeResult<SearchSummary> {
     }
 
     if !ctx.ctl.should_stop() {
-        walk_files(&on_disk, || {
-            let mut searcher = searcher_builder.build();
-            let matcher = matcher.clone();
-            let ctx = &ctx;
-            Box::new(move |path| {
-                if ctx.ctl.should_stop() {
-                    return WalkState::Quit;
-                }
-                ctx.search_file(path, &matcher, &mut searcher);
-                if ctx.ctl.stopped() { WalkState::Quit } else { WalkState::Continue }
-            })
-        });
+        walk_files(
+            &on_disk,
+            &|path| ctx.mask.has_directory_exclusions() && ctx.mask.excludes_dir(&rel_path(ctx.root, path)),
+            || {
+                let mut searcher = searcher_builder.build();
+                let matcher = matcher.clone();
+                let ctx = &ctx;
+                Box::new(move |path| {
+                    if ctx.ctl.should_stop() {
+                        return WalkState::Quit;
+                    }
+                    ctx.search_file(path, &matcher, &mut searcher);
+                    if ctx.ctl.stopped() { WalkState::Quit } else { WalkState::Continue }
+                })
+            },
+        );
     }
 
     let cancelled = ctx.ctl.cancelled.load(Relaxed) || req.cancel.is_cancelled();
@@ -176,7 +180,11 @@ pub(crate) type VisitFile<'s> = Box<dyn FnMut(&Path) -> WalkState + Send + 's>;
 /// them, while ignored files elsewhere (`.env`) and hidden files and folders
 /// (`.github`, `.eslintrc`) are visited. `.git`, symlinks and archives (jar,
 /// zip: browsed, not searched) are never visited.
-pub(crate) fn walk_files<'s>(roots: &[PathBuf], mut visitor: impl FnMut() -> VisitFile<'s> + Send) {
+pub(crate) fn walk_files<'s>(
+    roots: &[PathBuf],
+    skip_dir: &'s (dyn Fn(&Path) -> bool + Sync),
+    mut visitor: impl FnMut() -> VisitFile<'s> + Send,
+) {
     let Some((first, rest)) = roots.split_first() else { return };
     let mut walk = WalkBuilder::new(first);
     for path in rest {
@@ -204,6 +212,9 @@ pub(crate) fn walk_files<'s>(roots: &[PathBuf], mut visitor: impl FnMut() -> Vis
             };
             let Some(file_type) = entry.file_type() else { return WalkState::Continue };
             if file_type.is_dir() {
+                if skip_dir(entry.path()) {
+                    return WalkState::Skip;
+                }
                 // The walker drops ignored files unseen, so the files of every walked
                 // directory come from listing it; the walker only picks the directories.
                 let Ok(children) = std::fs::read_dir(entry.path()) else { return WalkState::Continue };
@@ -595,3 +606,39 @@ mod tests {
         }
     }
 }
+
+#[cfg(test)]
+mod walk_tests {
+    use super::*;
+    use std::sync::Mutex;
+
+    #[test]
+    fn excluded_subtree_is_not_visited() {
+        let dir = tempfile::tempdir().unwrap();
+        let root = dir.path();
+        std::fs::create_dir_all(root.join("edge/device/build/deep")).unwrap();
+        std::fs::create_dir_all(root.join("edge/device/src")).unwrap();
+        std::fs::write(root.join("edge/device/build/deep/generated.go"), "hit").unwrap();
+        std::fs::write(root.join("edge/device/src/main.go"), "hit").unwrap();
+        let mask = FileMask::new(&[], &["**/build/**".into()]).unwrap();
+        let seen = Mutex::new(Vec::new());
+        walk_files(&[root.to_path_buf()], &|path| mask.excludes_dir(&rel_path(root, path)), || {
+            let seen = &seen;
+            Box::new(move |path| {
+                // No file-level mask here: a visit means the walker entered the subtree.
+                seen.lock().unwrap().push(rel_path(root, path));
+                WalkState::Continue
+            })
+        });
+        assert_eq!(*seen.lock().unwrap(), ["edge/device/src/main.go"]);
+        seen.lock().unwrap().clear();
+        walk_files(&[root.join("edge/device/build/deep")], &|path| mask.excludes_dir(&rel_path(root, path)), || {
+            let seen = &seen;
+            Box::new(move |path| {
+                seen.lock().unwrap().push(rel_path(root, path));
+                WalkState::Continue
+            })
+        });
+        assert!(seen.lock().unwrap().is_empty());
+    }
+}

crates/ide-search/src/files.rs

@@ -43,7 +43,7 @@ pub fn scope_files(
             on_disk.push(path);
         }
     }
-    walk_files(&on_disk, || {
+    walk_files(&on_disk, &|path| mask.has_directory_exclusions() && mask.excludes_dir(&rel_path(root, path)), || {
         let found = &found;
         let keep = &keep;
         Box::new(move |path| {

crates/ide-search/src/mask.rs

@@ -12,6 +12,7 @@ pub struct FileMask {
     exclude_name: GlobSet,
     exclude_path: GlobSet,
     has_include: bool,
+    exclude_dirs: GlobSet,
 }
 
 impl FileMask {
@@ -20,6 +21,7 @@ impl FileMask {
     pub fn new(include: &[String], exclude: &[String]) -> IdeResult<Self> {
         let mut inc = Lists::default();
         let mut exc = Lists::default();
+        let mut dirs = Lists::default();
         for (entries, is_include_list) in [(include, true), (exclude, false)] {
             for mask in entries.iter().flat_map(|e| e.split(',')) {
                 let mask = mask.trim();
@@ -32,10 +34,20 @@ impl FileMask {
                 }
                 let target = if is_include_list != negated { &mut inc } else { &mut exc };
                 target.push(mask)?;
+                // Only a trailing /** guarantees that every descendant is excluded.
+                // File masks and inclusion masks cannot safely prune a directory.
+                if is_include_list == negated
+                    && !mask.contains('\\')
+                    && let Some(prefix) = mask.strip_suffix("/**")
+                    && !prefix.is_empty()
+                {
+                    dirs.push(&format!("{prefix}/"))?;
+                }
             }
         }
         Ok(Self {
             has_include: inc.count > 0,
+            exclude_dirs: dirs.path.build().map_err(glob_error)?,
             include_name: inc.name.build().map_err(glob_error)?,
             include_path: inc.path.build().map_err(glob_error)?,
             exclude_name: exc.name.build().map_err(glob_error)?,
@@ -43,6 +55,20 @@ impl FileMask {
         })
     }
 
+    pub(crate) fn has_directory_exclusions(&self) -> bool {
+        !self.exclude_dirs.is_empty()
+    }
+
+    /// Whether an exclusion covers every file below this directory. This is
+    /// deliberately conservative; ordinary masks still filter individual files.
+    pub(crate) fn excludes_dir(&self, rel_path: &str) -> bool {
+        if self.exclude_dirs.is_empty() {
+            return false;
+        }
+        let path = format!("{rel_path}/");
+        path.match_indices('/').any(|(i, _)| self.exclude_dirs.is_match(&path[..=i]))
+    }
+
     /// `rel_path` uses `/` separators.
     pub fn matches(&self, rel_path: &str) -> bool {
         let name = rel_path.rsplit('/').next().unwrap_or(rel_path);
@@ -133,6 +159,60 @@ mod tests {
         assert!(!m.matches("Cargo.lock"));
     }
 
+    #[test]
+    fn only_complete_subtree_exclusions_prune_directories() {
+        let m = mask(&["*.go"], &["**/node_modules/**", "edge/device/build/**"]);
+        for dir in [
+            "node_modules",
+            "edge/node_modules",
+            "edge/device/build",
+            "edge/device/build/deep",
+            "edge/node_modules/pkg/lib",
+        ] {
+            assert!(m.excludes_dir(dir), "{dir}");
+        }
+        for dir in ["edge", "edge/device", "internal/build", "src.go"] {
+            assert!(!m.excludes_dir(dir), "{dir}");
+        }
+        for pattern in ["*.go", "build", "build/*", "build/", "build/**/*.go"] {
+            assert!(!mask(&[], &[pattern]).excludes_dir("build"), "{pattern}");
+        }
+    }
+
+    #[test]
+    fn directory_pruning_preserves_mask_negation_semantics() {
+        assert!(mask(&["!vendor/**"], &[]).excludes_dir("vendor"));
+        assert!(!mask(&[], &["!vendor/**"]).excludes_dir("vendor"));
+        // Exclusions already win over inclusions in FileMask, irrespective of order.
+        let m = mask(&["vendor/keep.go"], &["vendor/**"]);
+        assert!(m.excludes_dir("vendor"));
+        assert!(!m.matches("vendor/keep.go"));
+        assert!(mask(&[], &["./vendor/**, **/node_modules/**"]).excludes_dir("vendor"));
+    }
+
+    #[test]
+    fn directory_pruning_uses_the_same_case_rules_as_files() {
+        let m = mask(&[], &["Vendor/**"]);
+        let case_insensitive = cfg!(any(target_os = "macos", target_os = "windows"));
+        assert_eq!(m.excludes_dir("vendor"), case_insensitive);
+        assert_eq!(m.matches("vendor/a.go"), !case_insensitive);
+    }
+
+    #[test]
+    fn pruned_directory_descendants_are_already_excluded() {
+        for pattern in ["vendor/**", "**/build/**", "modules/*/build/**", "[ab]/**", "**/**"] {
+            let m = mask(&[], &[pattern]);
+            for dir in ["vendor", "vendor/deep", "build", "a", "modules/a/build", "modules/a/src", "x/build/y"] {
+                if m.excludes_dir(dir) {
+                    for file in ["main.go", "deep/lib.go", ".hidden/config", "node_modules/a.js"] {
+                        assert!(!m.matches(&format!("{dir}/{file}")), "{pattern}: {dir}/{file}");
+                    }
+                }
+            }
+        }
+        assert!(!mask(&[], &[r"escaped\*/**"]).excludes_dir("escaped*"));
+    }
+
     #[test]
     fn invalid_glob() {
         let err = FileMask::new(&["a[".into()], &[]).unwrap_err();

crates/ide-search/tests/search.rs

@@ -797,3 +797,42 @@ fn search_context_reads_non_utf8_files() {
     let p = project(&[("a.rs", &gbk("foo(\"新增\"); // 中文 foo\n"))]);
     assert_eq!(run_context(p.path(), C::InComments), vec![("a.rs".to_owned(), 0, vec![(17, 20)])]);
 }
+
+#[test]
+fn subtree_masks_preserve_results_across_search_scopes() {
+    let p = project(&[
+        ("edge/build/deep/generated.go", b"hit"),
+        ("edge/src/main.go", b"hit"),
+        ("internal/build/build.go", b"hit"),
+        ("edge/build-notes.go", b"hit"),
+    ]);
+    let q = SearchQuery { exclude: vec!["edge/build/**".into()], ..query("hit") };
+    let (views, _) = run(p.path(), &q);
+    assert_eq!(paths(&views), ["edge/build-notes.go", "edge/src/main.go", "internal/build/build.go"]);
+    let mask = ide_search::FileMask::new(&q.include, &q.exclude).unwrap();
+    for scope in [
+        SearchScope::Directory { path: "edge/build".into() },
+        SearchScope::Files { paths: vec!["edge/build/deep/generated.go".into()] },
+    ] {
+        let (views, _) = run(p.path(), &SearchQuery { scope: scope.clone(), ..q.clone() });
+        assert!(views.is_empty());
+        assert!(ide_search::scope_files(p.path(), &scope, &mask, None, &CancellationToken::new()).unwrap().is_empty());
+    }
+    // A file-name exclusion must not prune a same-named directory.
+    let (views, _) = run(p.path(), &SearchQuery { exclude: vec!["build".into()], ..query("hit") });
+    assert_eq!(views.len(), 4);
+}
+
+#[test]
+fn ignore_whitelists_do_not_override_explicit_subtree_masks() {
+    let p = project(&[
+        (".gitignore", b"generated/*\n!generated/keep/\n"),
+        ("generated/keep/.gitignore", b"!keep.go\n"),
+        ("generated/keep/keep.go", b"needle"),
+        ("src/main.go", b"needle"),
+    ]);
+    let (views, _) = run(p.path(), &query("needle"));
+    assert_eq!(paths(&views), ["generated/keep/keep.go", "src/main.go"]);
+    let (views, _) = run(p.path(), &SearchQuery { exclude: vec!["generated/**".into()], ..query("needle") });
+    assert_eq!(paths(&views), ["src/main.go"]);
+}

crates/ide-tools/src/lib.rs

@@ -104,6 +104,17 @@ pub enum InstallEvent {
     Progress { fraction: Option<f64>, message: String },
 }
 
+/// A newer version of a tool the IDE installed, as its install source offers it now.
+#[derive(Clone, Debug, PartialEq, Serialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ToolUpdate {
+    pub name: String,
+    /// The installed version.
+    pub current: String,
+    /// The version installing the tool again would get.
+    pub latest: String,
+}
+
 #[derive(Serialize, Deserialize)]
 struct Manifest {
     version: Option<String>,
@@ -1410,10 +1421,16 @@ impl Tools {
             .ok_or_else(|| IdeError::new(ErrorKind::Io, format!("`{main}` was not found in {}", dl.name)))?;
         let rel = found.strip_prefix(&pkg).expect("inside pkg").to_path_buf();
         let final_dir = self.root.join(spec.name);
-        if final_dir.exists() {
-            std::fs::remove_dir_all(&final_dir)?;
-        }
-        std::fs::rename(&pkg, &final_dir)?;
+        // Downloads made by the IDE itself are not quarantined, but archives may carry the flag.
+        clear_quarantine(&pkg);
+        // The previous install is removed in the background once replaced: deleting a large
+        // tool takes a while, and there is nothing left to cancel by then.
+        let previous = self.root.join(format!(".previous-{}", spec.name));
+        let _ = std::fs::remove_dir_all(&previous);
+        put_in_place(&pkg, &final_dir, &previous, cancel)?;
+        std::thread::spawn(move || {
+            let _ = std::fs::remove_dir_all(previous);
+        });
         let target = final_dir.join(&rel);
         let bin = final_dir.join("bin");
         if is_bundle(main) {
@@ -1428,11 +1445,80 @@ impl Tools {
                 archive::link_executable(&bin, main, &target)?;
             }
         }
-        // Downloads made by the IDE itself are not quarantined, but archives may carry the flag.
-        clear_quarantine(&final_dir);
         self.write_manifest(spec.name, &Manifest { version: Some(dl.version.clone()), source: Some(dl.url.clone()) })
     }
 
+    /// Newer versions of the tools the IDE installed into its tools folder, for the install
+    /// sources that can be asked: release downloads (GitHub, Open VSX, Maven Central, …) and
+    /// npm packages. A tool whose lookup fails (offline, rate limited) is left out.
+    pub fn updates(&self, cancel: &CancellationToken) -> IdeResult<Vec<ToolUpdate>> {
+        let installed: Vec<(&ToolSpec, Method, String)> = TOOLS
+            .iter()
+            .filter_map(|spec| {
+                let method = self.install_method(spec);
+                Some((spec, method, self.installed_version(spec, method)?))
+            })
+            .collect();
+        let updates = std::thread::scope(|scope| {
+            let lookups: Vec<_> = installed
+                .iter()
+                .map(|(spec, method, current)| {
+                    scope.spawn(move || match self.for_method(*method).latest_version(*method, cancel) {
+                        Ok(Some(latest)) if latest != *current => {
+                            Some(ToolUpdate { name: spec.name.into(), current: current.clone(), latest })
+                        }
+                        Ok(_) => None,
+                        Err(e) => {
+                            tracing::info!("update check for {}: {}", spec.name, e.message);
+                            None
+                        }
+                    })
+                })
+                .collect();
+            lookups.into_iter().filter_map(|lookup| lookup.join().ok().flatten()).collect()
+        });
+        if cancel.is_cancelled() {
+            return Err(IdeError::cancelled());
+        }
+        Ok(updates)
+    }
+
+    /// The version of `spec` in the IDE's tools folder, when `method` (how it was installed)
+    /// can tell the latest one.
+    fn installed_version(&self, spec: &ToolSpec, method: Method) -> Option<String> {
+        match method {
+            Method::Release { .. } => {
+                managed_bin_dir(&self.root, spec, self.platform).and_then(|dir| self.exe_in(&dir, spec.commands[0]))?;
+                self.manifest(spec.name)?.version
+            }
+            // A pinned package (`typescript@6`) stays on its major version.
+            Method::Npm { packages } if npm_name(packages[0]) == packages[0] => self.npm_package_version(packages[0]),
+            _ => None,
+        }
+    }
+
+    /// The version installing with `method` would get now.
+    fn latest_version(&self, method: Method, cancel: &CancellationToken) -> IdeResult<Option<String>> {
+        match method {
+            Method::Release { source, assets, .. } => {
+                let http = Http::new(&self.system_path)?;
+                Ok(Some(self.resolve_release(&http, source, assets, cancel)?.version))
+            }
+            Method::Npm { packages } => {
+                let (manager, _) = self.npm_manager()?;
+                let mut c = self.command(manager);
+                // The registry the user's npm configuration names (a mirror, a proxy). A cold npm
+                // on a slow registry takes several seconds per package, more when run side by side.
+                c.args(["view", packages[0], "version"]).current_dir(&self.root);
+                match run_quiet(c, Duration::from_secs(60)) {
+                    Some((true, out)) => Ok(out.lines().map(str::trim).rfind(|l| !l.is_empty()).map(String::from)),
+                    _ => Err(IdeError::unavailable(format!("cannot look up the latest {}", packages[0]))),
+                }
+            }
+            _ => Ok(None),
+        }
+    }
+
     /// Removes a tool the IDE installed.
     pub fn uninstall(&self, name: &str, langs: &[LanguageConfig]) -> IdeResult<ToolInfo> {
         match registry::find(name) {
@@ -1563,6 +1649,25 @@ fn fetch_verified(
 }
 
 /// Removes the quarantine flag archives may carry, so macOS runs what was unpacked.
+/// Moves the unpacked `pkg` to `dest`, moving a previous install aside to `aside`.
+/// Cancelling stops it until then: the last point where the previous install is untouched.
+fn put_in_place(pkg: &Path, dest: &Path, aside: &Path, cancel: &CancellationToken) -> IdeResult<()> {
+    if cancel.is_cancelled() {
+        return Err(IdeError::cancelled());
+    }
+    let replaced = dest.exists();
+    if replaced {
+        std::fs::rename(dest, aside)?;
+    }
+    if let Err(e) = std::fs::rename(pkg, dest) {
+        if replaced {
+            let _ = std::fs::rename(aside, dest);
+        }
+        return Err(e.into());
+    }
+    Ok(())
+}
+
 fn clear_quarantine(dir: &Path) {
     #[cfg(target_os = "macos")]
     {