fix(lsp): Find usages in unopened files outside the language server's scope (#89)

Reference-based features only asked the language server, which analyses its configured scope (e.g. Pyright's `include`) plus open files, so usages in unopened files outside that scope were silently missing.

Find Usages, Show Usages, usage counts, Safe Delete of a symbol, Rename and incoming calls now also search project files that contain the symbol's name (whole word, same language, .gitignore/excludes respected, unsaved edits included, up to 300 files, cancellable). Candidates the first answer didn't cover are opened in the server temporarily, queried and closed again. Files the user has open are never touched, and diagnostics for the temporary files are dropped. An empty result while the server is still indexing is retried once indexing ends. When results may still be incomplete (indexing, file cap), the usages UI says so. `lsp_references` takes a RequestId and is cancelled by newer searches. Not covered yet: the Safe Delete scan when deleting a file or directory.

Fixes #83

Claude-Session: https://claude.ai/code/session_01VUYsdXA2nkF5v6zsC93dpn

src-tauri/src/commands/lsp.rs

@@ -106,16 +106,25 @@ pub async fn lsp_virtual_document(
     project!(window, state).lsp.virtual_document(&uri).await
 }
 
+/// References of the symbol at `pos`. `project_wide` also searches project files
+/// outside the language server's analysis scope; bulk scans over many symbols
+/// leave it off. Cancel with `cancel_request(request)`.
 #[tauri::command]
 #[specta::specta]
 pub async fn lsp_references(
     window: Window,
     state: State<'_, AppState>,
+    request: RequestId,
     doc: DocId,
     pos: Pos,
     include_declaration: bool,
-) -> IdeResult<Vec<Location>> {
-    project!(window, state).lsp.references(doc, pos, include_declaration).await
+    project_wide: bool,
+) -> IdeResult<References> {
+    let lsp = project!(window, state).lsp.clone();
+    let cancel = state.begin_request(request);
+    let result = lsp.references(doc, pos, include_declaration, project_wide, cancel).await;
+    state.end_request(request);
+    result
 }
 
 #[tauri::command]

src-tauri/src/state.rs

@@ -442,6 +442,12 @@ impl AppState {
             content_watchers: Mutex::new(content_watchers),
             _scratch_watcher: scratch_watcher,
         });
+        {
+            let weak = Arc::downgrade(&project);
+            project.lsp.set_candidates_hook(Box::new(move |q, cancel| {
+                weak.upgrade().map(|p| p.reference_candidates(q, cancel)).unwrap_or_default()
+            }));
+        }
         self.projects.write().insert(window.to_owned(), project.clone());
         Ok(project)
     }
@@ -609,6 +615,33 @@ impl Project {
         out
     }
 
+    /// Project files of `q.languages` under `q.root` containing `q.word` as a whole
+    /// word (unsaved buffers included; excluded roots, ignored names and
+    /// `.gitignore`d files skipped): the files a references search opens on its server.
+    pub fn reference_candidates(
+        &self,
+        q: &ide_lsp::CandidateQuery,
+        cancel: &CancellationToken,
+    ) -> ide_lsp::CandidateFiles {
+        if !q.root.starts_with(&self.root) {
+            return ide_lsp::CandidateFiles::default();
+        }
+        let query = ide_search::WordQuery {
+            word: q.word.clone(),
+            dir: q.root.clone(),
+            exclude: self.search_excludes(),
+            limit: q.limit,
+        };
+        let filter = |rel: &str| q.languages.contains(&self.languages.detect(&self.root.join(rel), None));
+        match ide_search::files_with_word(&self.root, &query, Some(&filter), &|p| self.documents.text_of(p), cancel) {
+            Ok(found) => ide_lsp::CandidateFiles { files: found.files, limit_hit: found.limit_hit },
+            Err(e) => {
+                tracing::debug!("reference candidates: {}", e.message);
+                ide_lsp::CandidateFiles::default()
+            }
+        }
+    }
+
     /// `files.exclude`, the ignored names and the effective excluded roots (user-marked and detected).
     pub fn exclude_globs(&self) -> Vec<String> {
         exclude_globs(&self.settings.effective(), &self.detected_roots.read())