Improve messaging and dashboard reliability

tests/dashboard/conversations.test.tsx

@@ -12,6 +12,7 @@ import { ConversationsPage } from '../../apps/dashboard/src/features/conversatio
 interface ChatFixtureOptions {
   username: string;
   roomId: string;
+  lastMessageTime?: number;
   unread?: boolean;
   isFromUs?: boolean;
   lastMessageSnippet?: string;
@@ -24,7 +25,7 @@ function chatFixture(options: ChatFixtureOptions) {
     roomName: options.username,
     roomId: options.roomId,
     url: `https://chat.reddit.com/room/${options.roomId}`,
-    lastMessageTime: 1_786_000_000_000,
+    lastMessageTime: options.lastMessageTime ?? 1_786_000_000_000,
     lastMessageSnippet: options.lastMessageSnippet ?? `Latest from ${options.username}`,
     isFromUs: options.isFromUs ?? false,
     unread: options.unread ?? false,
@@ -141,6 +142,36 @@ describe('ConversationsPage', () => {
     );
   });
 
+  it('orders conversations by latest message activity', async () => {
+    const oldest = chatFixture({ username: 'oldest', roomId: 'room-oldest', lastMessageTime: 100 });
+    const newest = chatFixture({ username: 'newest', roomId: 'room-newest', lastMessageTime: 300 });
+    const middle = chatFixture({ username: 'middle', roomId: 'room-middle', lastMessageTime: 200 });
+    server.use(http.get('/api/conversations', () => HttpResponse.json([oldest, newest, middle])));
+    renderConversations();
+
+    await screen.findByRole('button', { name: /u\/newest/ });
+    expect(screen.getAllByRole('button', { name: /u\/(?:oldest|newest|middle)/ }).map((button) => button.getAttribute('aria-label')))
+      .toEqual([
+        expect.stringContaining('u/newest'),
+        expect.stringContaining('u/middle'),
+        expect.stringContaining('u/oldest'),
+      ]);
+  });
+
+  it('shows short relative times for the latest message', async () => {
+    const now = Date.now();
+    const minutesAgo = chatFixture({ username: 'minutes', roomId: 'room-minutes', lastMessageTime: now - (5 * 60_000) });
+    const daysAgo = chatFixture({ username: 'days', roomId: 'room-days', lastMessageTime: now - (2 * 86_400_000) });
+    server.use(http.get('/api/conversations', () => HttpResponse.json([daysAgo, minutesAgo])));
+    renderConversations();
+
+    const recentTime = await screen.findByText('5m ago');
+    expect(recentTime.tagName).toBe('TIME');
+    expect(recentTime).toHaveAttribute('dateTime', new Date(minutesAgo.lastMessageTime).toISOString());
+    expect(recentTime).toHaveAttribute('title');
+    expect(screen.getByText('2d ago')).toBeInTheDocument();
+  });
+
   it('marks and filters conversations with received images and renders the images in chat', async () => {
     const imageChat = chatFixture({
       username: 'alice',