chore(deps): update dependency vitest to v4

apps/penpal/frontend/package.json

@@ -46,6 +46,6 @@
     "typescript": "~5.9.0",
     "unist-util-visit": "^5.1.0",
     "vite": "^7.0.0",
-    "vitest": "^3.0.0"
+    "vitest": "^4.0.0"
   }
 }

apps/penpal/frontend/src/App.test.tsx

@@ -8,6 +8,7 @@ vi.mock('./api', () => ({
   isDesktopApp: false,
   api: {
     listProjects: vi.fn().mockResolvedValue([]),
+    getRecentFiles: vi.fn().mockResolvedValue([]),
     getInReview: vi.fn().mockResolvedValue([]),
   },
 }));
@@ -19,7 +20,7 @@ vi.mock('./hooks/useSSE', () => ({
 describe('App', () => {
   it('renders the layout', async () => {
     render(<App />);
-    // The router redirects / to /workspace/default
+    // With no projects, IndexRedirect falls back to /recent
     expect(await screen.findByTestId('app-layout')).toBeInTheDocument();
   });
 

apps/penpal/frontend/src/test/setup.ts

@@ -1,16 +1,5 @@
 import '@testing-library/jest-dom';
 
-// Suppress unhandled AbortSignal rejections from react-router in jsdom.
-// Node 24+ (undici v7) rejects jsdom's AbortSignal polyfill as not a "real" instance.
-// See: https://github.com/vitest-dev/vitest/issues/8374
-// This will be unnecessary once we upgrade to Vitest 4.
-process.removeAllListeners('unhandledRejection');
-process.on('unhandledRejection', (reason: unknown) => {
-  if (reason instanceof TypeError && String(reason).includes('AbortSignal')) return;
-  // Re-throw anything that isn't the known jsdom/undici mismatch
-  throw reason;
-});
-
 // Ensure localStorage is available in jsdom environment
 if (typeof globalThis.localStorage === 'undefined' || typeof globalThis.localStorage.clear !== 'function') {
   const store: Record<string, string> = {};