feat(webui): refresh session titles from live updates

webui/src/tests/useSessions.test.tsx

@@ -17,12 +17,20 @@ vi.mock("@/lib/api", async (importOriginal) => {
 });
 
 function fakeClient() {
+  const sessionUpdateHandlers = new Set<(chatId: string) => void>();
   return {
     status: "open" as const,
     defaultChatId: null as string | null,
     onStatus: () => () => {},
     onError: () => () => {},
     onChat: () => () => {},
+    onSessionUpdate: (handler: (chatId: string) => void) => {
+      sessionUpdateHandlers.add(handler);
+      return () => sessionUpdateHandlers.delete(handler);
+    },
+    emitSessionUpdate: (chatId: string) => {
+      for (const handler of sessionUpdateHandlers) handler(chatId);
+    },
     sendMessage: vi.fn(),
     newChat: vi.fn(),
     attach: vi.fn(),
@@ -87,6 +95,45 @@ describe("useSessions", () => {
     expect(result.current.sessions.map((s) => s.key)).toEqual(["websocket:chat-b"]);
   });
 
+  it("refreshes sessions when the websocket reports a session update", async () => {
+    vi.mocked(api.listSessions)
+      .mockResolvedValueOnce([
+        {
+          key: "websocket:chat-a",
+          channel: "websocket",
+          chatId: "chat-a",
+          createdAt: "2026-04-16T10:00:00Z",
+          updatedAt: "2026-04-16T10:00:00Z",
+          preview: "",
+        },
+      ])
+      .mockResolvedValueOnce([
+        {
+          key: "websocket:chat-a",
+          channel: "websocket",
+          chatId: "chat-a",
+          createdAt: "2026-04-16T10:00:00Z",
+          updatedAt: "2026-04-16T10:01:00Z",
+          title: "生成的小标题",
+          preview: "用户第一句话",
+        },
+      ]);
+    const client = fakeClient();
+
+    const { result } = renderHook(() => useSessions(), {
+      wrapper: wrap(client),
+    });
+
+    await waitFor(() => expect(result.current.sessions[0]?.title).toBeUndefined());
+
+    act(() => {
+      client.emitSessionUpdate("chat-a");
+    });
+
+    await waitFor(() => expect(result.current.sessions[0]?.title).toBe("生成的小标题"));
+    expect(api.listSessions).toHaveBeenCalledTimes(2);
+  });
+
   it("hydrates media_urls from historical user turns into UIMessage.images", async () => {
     // Round-trip check for the signed-media replay: the backend emits
     // ``media_urls`` on a historical user row and the hook must surface them