🤖 fix: prevent race condition when reloading with stale workspace (#943)

## Problem

On page reload in Electron, the app fails to restore the previously
selected workspace and instead shows the home page with this error:

```
Workspace 6164ccb357 no longer exists, clearing selection
```

## Root Cause

Two race conditions were causing this:

### 1. API connection timing
`WorkspaceContext`'s `loadWorkspaceMetadata()` returned early when `api`
was null (during initial 'connecting' state), but `setLoading(false)`
was still called. This caused `App` to render with empty metadata while
`selectedWorkspace` was restored from localStorage, triggering the
validation effect to clear the selection.

### 2. Missing metadata guard
Even after fixing the API timing, if `selectedWorkspace` from
localStorage referred to a deleted workspace, the `AIView` would try to
render before the validation effect could clear the stale selection.

## Solution

1. **Wait for API**: `loadWorkspaceMetadata` now returns a boolean
indicating success. The effect only calls `setLoading(false)` after
actual load. When `api` becomes available, the effect re-runs.

2. **Guard AIView render**: If `selectedWorkspace` exists but
`currentMetadata` is undefined, return `null` instead of rendering
`AIView`. The validation effect will clear the stale selection on the
next tick.

3. **Remove redundant effect**: Removed the simple validation effect
(lines 126-130) since the comprehensive one (lines 165-189) handles all
cases including missing fields update.

---

_Generated with `mux`_

Author: ammar-agent

src/browser/App.tsx

@@ -121,14 +121,6 @@ function AppInner() {
     prevWorkspaceRef.current = selectedWorkspace;
   }, [selectedWorkspace, telemetry]);
 
-  // Validate selectedWorkspace when metadata changes
-  // Clear selection if workspace was deleted
-  useEffect(() => {
-    if (selectedWorkspace && !workspaceMetadata.has(selectedWorkspace.workspaceId)) {
-      setSelectedWorkspace(null);
-    }
-  }, [selectedWorkspace, workspaceMetadata, setSelectedWorkspace]);
-
   // Track last-read timestamps for unread indicators
   const { lastReadTimestamps, onToggleUnread } = useUnreadTracking(selectedWorkspace);
 
@@ -571,15 +563,22 @@ function AppInner() {
             {selectedWorkspace ? (
               (() => {
                 const currentMetadata = workspaceMetadata.get(selectedWorkspace.workspaceId);
+                // Guard: Don't render AIView if workspace metadata not found.
+                // This can happen when selectedWorkspace (from localStorage) refers to a
+                // deleted workspace, or during a race condition on reload before the
+                // validation effect clears the stale selection.
+                if (!currentMetadata) {
+                  return null;
+                }
                 // Use metadata.name for workspace name (works for both worktree and local runtimes)
                 // Fallback to path-based derivation for legacy compatibility
                 const workspaceName =
-                  currentMetadata?.name ??
+                  currentMetadata.name ??
                   selectedWorkspace.namedWorkspacePath?.split("/").pop() ??
                   selectedWorkspace.workspaceId;
                 // Use live metadata path (updates on rename) with fallback to initial path
                 const workspacePath =
-                  currentMetadata?.namedWorkspacePath ?? selectedWorkspace.namedWorkspacePath ?? "";
+                  currentMetadata.namedWorkspacePath ?? selectedWorkspace.namedWorkspacePath ?? "";
                 return (
                   <ErrorBoundary
                     workspaceInfo={`${selectedWorkspace.projectName}/${workspaceName}`}
@@ -591,9 +590,9 @@ function AppInner() {
                       projectName={selectedWorkspace.projectName}
                       branch={workspaceName}
                       namedWorkspacePath={workspacePath}
-                      runtimeConfig={currentMetadata?.runtimeConfig}
-                      incompatibleRuntime={currentMetadata?.incompatibleRuntime}
-                      status={currentMetadata?.status}
+                      runtimeConfig={currentMetadata.runtimeConfig}
+                      incompatibleRuntime={currentMetadata.incompatibleRuntime}
+                      status={currentMetadata.status}
                     />
                   </ErrorBoundary>
                 );

src/browser/contexts/WorkspaceContext.tsx

@@ -118,7 +118,7 @@ export function WorkspaceProvider(props: WorkspaceProviderProps) {
   );
 
   const loadWorkspaceMetadata = useCallback(async () => {
-    if (!api) return;
+    if (!api) return false; // Return false to indicate metadata wasn't loaded
     try {
       const metadataList = await api.workspace.list(undefined);
       const metadataMap = new Map<string, FrontendWorkspaceMetadata>();
@@ -128,16 +128,22 @@ export function WorkspaceProvider(props: WorkspaceProviderProps) {
         metadataMap.set(metadata.id, metadata);
       }
       setWorkspaceMetadata(metadataMap);
+      return true; // Return true to indicate metadata was loaded
     } catch (error) {
       console.error("Failed to load workspace metadata:", error);
       setWorkspaceMetadata(new Map());
+      return true; // Still return true - we tried to load, just got empty result
     }
   }, [setWorkspaceMetadata, api]);
 
-  // Load metadata once on mount
+  // Load metadata once on mount (and again when api becomes available)
   useEffect(() => {
     void (async () => {
-      await loadWorkspaceMetadata();
+      const loaded = await loadWorkspaceMetadata();
+      if (!loaded) {
+        // api not available yet - effect will run again when api connects
+        return;
+      }
       // After loading metadata (which may trigger migration), reload projects
       // to ensure frontend has the updated config with workspace IDs
       await refreshProjects();