feat(quick-switcher): derive workspace dir from active tab

The explorer panel's explorerCurrentDir is hardcoded to null, so
the Quick Switcher's workspace toggle was a no-op. Rather than fix
the broken explorer flow, derive the workspace from the active
tab's filePath's parent directory — the most reliable source we
have without restructuring that panel.

deriveWorkspaceDir() handles POSIX and Windows paths (including
mixed separators and trailing separators), returns null for
untitled / empty inputs so the workspace toggle silently stays
off in those cases.

10 new tests cover POSIX, Windows, mixed-separator, trailing
separator, UNC, and invalid input paths.

Amit Haridas

src/quick-switcher/workspace-dir-resolver.js

@@ -0,0 +1,39 @@
+/**
+ * Workspace dir resolver for the Quick Switcher overlay.
+ *
+ * Derives a workspace directory from a single file path by returning its
+ * parent directory. Auto-detects path separator (Windows backslash vs
+ * POSIX forward slash).
+ *
+ * Returns null when no usable file path is supplied (untitled tab, no
+ * active tab) — the renderer then surfaces only recent + open tabs in
+ * the Quick Switcher, and the workspace toggle is a no-op.
+ *
+ * @module workspace-dir-resolver
+ */
+
+/**
+ * @param {string|null|undefined} filePath
+ * @returns {string|null} parent directory, or null if not derivable
+ */
+function deriveWorkspaceDir(filePath) {
+  if (typeof filePath !== 'string' || filePath.length === 0) return null;
+  // Trim trailing separators (so a path like '/foo/bar/' resolves to '/foo',
+  // not '/foo/bar').
+  let end = filePath.length;
+  while (end > 0 && (filePath[end - 1] === '/' || filePath[end - 1] === '\\')) {
+    end--;
+  }
+  if (end === 0) return null;
+  const trimmed = filePath.slice(0, end);
+  // Find the last separator of either kind — mixed paths are ambiguous
+  // but taking the last one of either kind matches what users mean when
+  // they paste a path with mixed separators.
+  const lastSlash = trimmed.lastIndexOf('/');
+  const lastBack = trimmed.lastIndexOf('\\');
+  const lastSep = Math.max(lastSlash, lastBack);
+  if (lastSep <= 0) return null;
+  return trimmed.slice(0, lastSep);
+}
+
+module.exports = { deriveWorkspaceDir };

src/renderer.js

@@ -223,10 +223,15 @@ function getCreateQuickSwitcherOverlay() {
 let _createInlineAiController;
 function getCreateInlineAiController() {
   if (!_createInlineAiController)
-    _createInlineAiController = require('./renderer/inline-ai-controller')
-      .createInlineAiController;
+    _createInlineAiController = require('./renderer/inline-ai-controller').createInlineAiController;
   return _createInlineAiController;
 }
+let _deriveWorkspaceDir;
+function getDeriveWorkspaceDir() {
+  if (!_deriveWorkspaceDir)
+    _deriveWorkspaceDir = require('./quick-switcher/workspace-dir-resolver').deriveWorkspaceDir;
+  return _deriveWorkspaceDir;
+}
 function getPrintPreview() {
   if (!_PrintPreview) _PrintPreview = require('./print-preview').PrintPreview;
   return _PrintPreview;
@@ -2578,7 +2583,18 @@ document.addEventListener('DOMContentLoaded', async () => {
       // v4.13.0 — explorer-driven workspace dir is the next iteration;
       // for now the workspace toggle is a no-op and we surface only
       // recent files + open tabs.
-      getWorkspaceDir: () => null,
+      getWorkspaceDir: () => {
+        // Derive workspace dir from the active tab's file (parent dir).
+        // The explorer panel's currentDir is hardcoded to null, so this is
+        // the most reliable source we have without restructuring that
+        // panel. Returns null for untitled tabs, which makes the workspace
+        // search toggle a no-op (recent + open tabs still surface).
+        const derive = getDeriveWorkspaceDir();
+        const active =
+          tabManager.activeTab ||
+          (tabManager.activeTabId && tabManager.tabs.get(tabManager.activeTabId));
+        return active ? derive(active.filePath) : null;
+      },
     });
     return quickSwitcherOverlayInstance;
   }
@@ -2593,7 +2609,9 @@ document.addEventListener('DOMContentLoaded', async () => {
     const create = getCreateInlineAiController();
     inlineAiControllerInstance = create({
       getEditorView: () => {
-        const active = tabManager.activeTab || (tabManager.activeTabId && tabManager.tabs.get(tabManager.activeTabId));
+        const active =
+          tabManager.activeTab ||
+          (tabManager.activeTabId && tabManager.tabs.get(tabManager.activeTabId));
         return active ? active.editorView : null;
       },
       electronAPI: window.electronAPI,

tests/workspace-dir-resolver.test.js

@@ -0,0 +1,54 @@
+/**
+ * @jest-environment node
+ *
+ * Workspace dir resolver — derive parent dir from a file path.
+ */
+
+const { deriveWorkspaceDir } = require('../src/quick-switcher/workspace-dir-resolver');
+
+describe('deriveWorkspaceDir', () => {
+  test('returns parent dir for a POSIX path', () => {
+    expect(deriveWorkspaceDir('/home/user/notes/readme.md')).toBe('/home/user/notes');
+  });
+
+  test('returns parent dir for a Windows path', () => {
+    expect(deriveWorkspaceDir('C:\\Users\\me\\notes\\readme.md')).toBe('C:\\Users\\me\\notes');
+  });
+
+  test('returns parent dir for a nested POSIX path', () => {
+    expect(deriveWorkspaceDir('/a/b/c/d/e.md')).toBe('/a/b/c/d');
+  });
+
+  test('auto-detects separator when path contains both', () => {
+    // A path with both — backslash takes precedence (Windows convention)
+    expect(deriveWorkspaceDir('C:\\foo/bar.txt')).toBe('C:\\foo');
+  });
+
+  test('returns null for a root-level POSIX file', () => {
+    expect(deriveWorkspaceDir('readme.md')).toBeNull();
+  });
+
+  test('returns null for an empty string', () => {
+    expect(deriveWorkspaceDir('')).toBeNull();
+  });
+
+  test('returns null for null / undefined / non-string', () => {
+    expect(deriveWorkspaceDir(null)).toBeNull();
+    expect(deriveWorkspaceDir(undefined)).toBeNull();
+    expect(deriveWorkspaceDir(42)).toBeNull();
+    expect(deriveWorkspaceDir({})).toBeNull();
+  });
+
+  test('returns null for a single-character filename', () => {
+    expect(deriveWorkspaceDir('/x')).toBeNull();
+    expect(deriveWorkspaceDir('\\x')).toBeNull();
+  });
+
+  test('preserves trailing separators', () => {
+    expect(deriveWorkspaceDir('/home/user/notes/')).toBe('/home/user');
+  });
+
+  test('handles UNC-style Windows path', () => {
+    expect(deriveWorkspaceDir('\\\\server\\share\\file.md')).toBe('\\\\server\\share');
+  });
+});