feat(FN-3843): add chat stream reattach support

Adds the changeset for FN-3843, completing the chat stream reattach feature for the `@runfusion/fusion` CLI package.

Fusion-Task-Id: FN-3843

packages/dashboard/app/hooks/__tests__/useChat.test.ts

@@ -17,6 +17,7 @@ vi.mock("../../api", () => ({
   updateChatSession: vi.fn(),
   deleteChatSession: vi.fn(),
   streamChatResponse: vi.fn(),
+  attachChatStream: vi.fn(),
   cancelChatResponse: vi.fn(),
   fetchAgents: vi.fn().mockResolvedValue([
     { id: "agent-001", name: "Alpha", role: "executor", state: "idle", icon: undefined, createdAt: "2026-04-08T00:00:00.000Z", updatedAt: "2026-04-08T00:00:00.000Z", metadata: {} },
@@ -50,6 +51,7 @@ const mockFetchChatMessages = vi.mocked(apiModule.fetchChatMessages);
 const mockUpdateChatSession = vi.mocked(apiModule.updateChatSession);
 const mockDeleteChatSession = vi.mocked(apiModule.deleteChatSession);
 const mockStreamChatResponse = vi.mocked(apiModule.streamChatResponse);
+const mockAttachChatStream = vi.mocked(apiModule.attachChatStream);
 const mockCancelChatResponse = vi.mocked(apiModule.cancelChatResponse);
 const mockFetchAgents = vi.mocked(apiModule.fetchAgents);
 
@@ -100,6 +102,7 @@ describe("useChat", () => {
     });
     mockDeleteChatSession.mockResolvedValue({ success: true });
     mockStreamChatResponse.mockReturnValue({ close: vi.fn(), isConnected: () => true });
+    mockAttachChatStream.mockReturnValue({ close: vi.fn(), isConnected: () => true });
     mockCancelChatResponse.mockResolvedValue({ success: true });
   });
 
@@ -2066,18 +2069,23 @@ describe("useChat", () => {
       });
     });
 
-    it("clears recovery streaming state when SSE delivers assistant message", async () => {
-      let subscribeHandler: Record<string, (event: MessageEvent) => void> = {};
-      mockSubscribeSse.mockImplementation((_url, options) => {
-        if (options?.events) {
-          subscribeHandler = options.events as typeof subscribeHandler;
-        }
-        return () => {};
-      });
-
+    it("clears recovery streaming state when attach stream completes", async () => {
       const session = { ...makeSession({ id: "session-001", agentId: "agent-001" }), isGenerating: true };
       mockFetchChatSessions.mockResolvedValueOnce({ sessions: [session] });
-      mockFetchChatMessages.mockResolvedValue({ messages: [] });
+      mockFetchChatMessages.mockResolvedValue({
+        messages: [
+          makeMessage({
+            id: "msg-assistant-001",
+            sessionId: "session-001",
+            role: "assistant",
+            content: "Generated response",
+          }),
+        ],
+      });
+      mockAttachChatStream.mockImplementation((_sessionId, handlers) => {
+        setTimeout(() => handlers.onDone?.({ messageId: "msg-assistant-001" }), 0);
+        return { close: vi.fn(), isConnected: () => true };
+      });
 
       const { result } = renderHook(() => useChat("proj-123"));
 
@@ -2089,24 +2097,6 @@ describe("useChat", () => {
         result.current.selectSession("session-001");
       });
 
-      await waitFor(() => {
-        expect(result.current.isStreaming).toBe(true);
-      });
-
-      // Simulate SSE delivering the completed assistant message
-      const assistantMessage = makeMessage({
-        id: "msg-assistant-001",
-        sessionId: "session-001",
-        role: "assistant",
-        content: "Generated response",
-      });
-
-      act(() => {
-        subscribeHandler["chat:message:added"](
-          new MessageEvent("chat:message:added", { data: JSON.stringify(assistantMessage) }),
-        );
-      });
-
       await waitFor(() => {
         expect(result.current.isStreaming).toBe(false);
         expect(result.current.streamingText).toBe("");

packages/dashboard/app/hooks/__tests__/useQuickChat.test.ts

@@ -11,6 +11,7 @@ vi.mock("../../api", () => ({
   createChatSession: vi.fn(),
   fetchChatMessages: vi.fn(),
   streamChatResponse: vi.fn(),
+  attachChatStream: vi.fn(),
   cancelChatResponse: vi.fn(),
 }));
 
@@ -20,6 +21,7 @@ const mockFetchChatSession = vi.mocked(apiModule.fetchChatSession);
 const mockCreateChatSession = vi.mocked(apiModule.createChatSession);
 const mockFetchChatMessages = vi.mocked(apiModule.fetchChatMessages);
 const mockStreamChatResponse = vi.mocked(apiModule.streamChatResponse);
+const mockAttachChatStream = vi.mocked(apiModule.attachChatStream);
 const mockCancelChatResponse = vi.mocked(apiModule.cancelChatResponse);
 
 function makeSession(overrides: Partial<ChatSession> & Pick<ChatSession, "id" | "agentId">): ChatSession {
@@ -57,6 +59,7 @@ describe("useQuickChat", () => {
       session: { ...makeSession({ id: "session-001", agentId: "agent-001" }), isGenerating: false },
     });
     mockStreamChatResponse.mockReturnValue({ close: vi.fn(), isConnected: () => true });
+    mockAttachChatStream.mockReturnValue({ close: vi.fn(), isConnected: () => true });
     mockCancelChatResponse.mockResolvedValue({ success: true });
   });
 
@@ -1305,22 +1308,18 @@ describe("useQuickChat", () => {
       });
     });
 
-    it("clears recovery streaming state when polling detects generation complete", async () => {
-      vi.useFakeTimers({ shouldAdvanceTime: true });
-
+    it("clears recovery streaming state when attach stream completes", async () => {
       const session = { ...makeSession({ id: "session-001", agentId: "agent-001" }), isGenerating: true };
       mockFetchResumeChatSession.mockResolvedValue({ session });
-      mockFetchChatMessages.mockResolvedValue({ messages: [] });
-
-      // After first poll, server reports generation is done and has a new assistant message
-      mockFetchChatSession.mockResolvedValue({
-        session: { ...makeSession({ id: "session-001", agentId: "agent-001" }), isGenerating: false },
-      });
       mockFetchChatMessages.mockResolvedValue({
         messages: [
           { id: "msg-1", sessionId: "session-001", role: "assistant", content: "Done", thinkingOutput: null, metadata: null, createdAt: new Date().toISOString() },
         ],
       });
+      mockAttachChatStream.mockImplementation((_sessionId, handlers) => {
+        setTimeout(() => handlers.onDone?.({ messageId: "msg-1" }), 0);
+        return { close: vi.fn(), isConnected: () => true };
+      });
 
       const { result } = renderHook(() => useQuickChat("proj-123"));
 
@@ -1328,22 +1327,11 @@ describe("useQuickChat", () => {
         await result.current.switchSession("agent-001");
       });
 
-      await waitFor(() => {
-        expect(result.current.isStreaming).toBe(true);
-      });
-
-      // Advance time to trigger the polling interval (3s)
-      await act(async () => {
-        vi.advanceTimersByTime(3500);
-      });
-
       await waitFor(() => {
         expect(result.current.isStreaming).toBe(false);
         expect(result.current.streamingText).toBe("");
         expect(result.current.messages.some((m) => m.id === "msg-1")).toBe(true);
       });
-
-      vi.useRealTimers();
     });
   });
 });