fix(web): close P3 chat re-review findings

apps/web/src/spa/pages/chat-error-boundary.spec.tsx

@@ -2,7 +2,16 @@ import { act } from 'react';
 import { createRoot, type Root } from 'react-dom/client';
 import { createMemoryRouter, RouterProvider, type RouteObject } from 'react-router-dom';
 import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from 'vitest';
-import { ChatRouteErrorBoundary } from './chat-error-boundary';
+
+const { useSessionMock } = vi.hoisted(() => ({
+  useSessionMock: vi.fn(),
+}));
+
+vi.mock('@/lib/auth-client', () => ({
+  useSession: useSessionMock,
+}));
+
+import { routes } from '@/routes';
 
 beforeAll(() => {
   Object.defineProperty(globalThis, 'IS_REACT_ACT_ENVIRONMENT', {
@@ -19,6 +28,25 @@ function Boom(): never {
   throw new Error('render blew up');
 }
 
+/** Recursively clones the real exported route table, replacing only the
+ * `/chat` route's `element` with `<Boom />` — every other route (including
+ * the real `AuthGuard` nesting and the real `/chat` `errorElement`) is left
+ * exactly as exported. This is what makes the test fail if a future change
+ * removes the real route's `errorElement`, unlike a hand-built independent
+ * route tree that could drift from production undetected. */
+function replaceChatElementWithBoom(nodes: RouteObject[]): RouteObject[] {
+  return nodes.map((node) => {
+    const cloned: RouteObject = { ...node };
+    if (cloned.path === '/chat') {
+      cloned.element = <Boom />;
+    }
+    if (cloned.children) {
+      cloned.children = replaceChatElementWithBoom(cloned.children);
+    }
+    return cloned;
+  });
+}
+
 let root: Root | null;
 let container: HTMLElement;
 
@@ -28,13 +56,14 @@ afterEach(async () => {
   });
   document.body.replaceChildren();
   root = null;
+  useSessionMock.mockReset();
 });
 
 describe('ChatRouteErrorBoundary', () => {
   it('renders a recoverable, non-blank fallback when the /chat route element throws during render', async () => {
-    const routeObjects: RouteObject[] = [
-      { path: '/chat', element: <Boom />, errorElement: <ChatRouteErrorBoundary /> },
-    ];
+    useSessionMock.mockReturnValue({ data: { user: { id: 'user-1' } }, isPending: false });
+
+    const routeObjects = replaceChatElementWithBoom(routes);
     const router = createMemoryRouter(routeObjects, { initialEntries: ['/chat'] });
 
     container = document.createElement('div');