feat(FN-1764): merge fusion/fn-1764

packages/dashboard/app/hooks/useLiveTranscript.ts

@@ -17,11 +17,53 @@ export interface TranscriptEntry {
   content?: string;
 }
 
+/**
+ * Hook that manages live transcript streaming for a task.
+ *
+ * Features project-context isolation to prevent cross-project transcript bleed:
+ * - Tracks project context version to detect stale events after project switches
+ * - Resets entries and connection state immediately on context change
+ * - Rejects stale SSE events from previous EventSource instances
+ *
+ * When `taskId` changes, a new SSE connection is opened for the new task.
+ * When `projectId` changes, all state is reset and a new connection is opened.
+ */
 export function useLiveTranscript(taskId: string | undefined, projectId?: string) {
   const [entries, setEntries] = useState<TranscriptEntry[]>([]);
   const [isConnected, setIsConnected] = useState(false);
+
+  // Refs for state that needs to survive re-renders
   const esRef = useRef<EventSource | null>(null);
 
+  // Track the project context version to detect stale events after project switches.
+  // Incremented whenever projectId changes, invalidating any in-flight SSE handlers.
+  const projectContextVersionRef = useRef(0);
+
+  // Track previous values to detect context changes
+  const previousTaskIdRef = useRef<string | undefined>(taskId);
+  const previousProjectIdRef = useRef<string | undefined>(projectId);
+
+  // Detect context changes and reset state immediately
+  const contextChanged =
+    previousTaskIdRef.current !== taskId ||
+    previousProjectIdRef.current !== projectId;
+
+  if (contextChanged) {
+    previousTaskIdRef.current = taskId;
+    previousProjectIdRef.current = projectId;
+    projectContextVersionRef.current++;
+
+    // Close existing EventSource
+    if (esRef.current) {
+      esRef.current.close();
+      esRef.current = null;
+    }
+
+    // Reset state immediately to prevent stale data visibility
+    setEntries([]);
+    setIsConnected(false);
+  }
+
   useEffect(() => {
     if (!taskId) {
       setEntries([]);
@@ -29,6 +71,9 @@ export function useLiveTranscript(taskId: string | undefined, projectId?: string
       return;
     }
 
+    // Capture context version at effect start - stale events will be rejected
+    const contextVersionAtStart = projectContextVersionRef.current;
+
     // Build stream URL with optional projectId for multi-project support
     let url = `/api/tasks/${encodeURIComponent(taskId)}/logs/stream`;
     if (projectId) {
@@ -39,6 +84,11 @@ export function useLiveTranscript(taskId: string | undefined, projectId?: string
     esRef.current = es;
 
     es.addEventListener("agent:log", (event) => {
+      // Reject events from stale contexts (project/task switch)
+      if (projectContextVersionRef.current !== contextVersionAtStart) {
+        return;
+      }
+
       try {
         const raw = JSON.parse(event.data) as Partial<TranscriptEntry>;
         // Normalize: canonical `text` field, with legacy `content` fallback
@@ -53,13 +103,28 @@ export function useLiveTranscript(taskId: string | undefined, projectId?: string
       } catch { /* skip malformed events */ }
     });
 
-    es.addEventListener("open", () => setIsConnected(true));
-    es.addEventListener("error", () => setIsConnected(false));
+    es.addEventListener("open", () => {
+      // Only update connected state if not stale
+      if (projectContextVersionRef.current === contextVersionAtStart) {
+        setIsConnected(true);
+      }
+    });
+
+    es.addEventListener("error", () => {
+      // Only update connected state if not stale
+      if (projectContextVersionRef.current === contextVersionAtStart) {
+        setIsConnected(false);
+      }
+    });
 
     return () => {
       es.close();
       esRef.current = null;
-      setIsConnected(false);
+
+      // Only reset state if not stale
+      if (projectContextVersionRef.current === contextVersionAtStart) {
+        setIsConnected(false);
+      }
     };
   }, [taskId, projectId]);