fix(ui): prevent async listener leaks on back navigation

src/components/layout/NotificationCenter.tsx

@@ -66,10 +66,12 @@ export default function NotificationCenter() {
   }, [projectId]);
 
   useEffect(() => {
+    let cancelled = false;
     let unlisten: (() => void) | null = null;
 
     const setup = async () => {
-      unlisten = await listen<NewNotificationEvent>("new-notification", (event) => {
+      try {
+        const cleanup = await listen<NewNotificationEvent>("new-notification", (event) => {
           const incoming = event.payload.notification;
 
           if (projectId && incoming.project_id !== projectId) {
@@ -83,11 +85,22 @@ export default function NotificationCenter() {
 
           void showSystemNotification(incoming);
         });
+
+        if (cancelled) {
+          cleanup();
+          return;
+        }
+
+        unlisten = cleanup;
+      } catch (error: unknown) {
+        console.error("Failed to subscribe to notifications", error);
+      }
     };
 
     void setup();
 
     return () => {
+      cancelled = true;
       if (unlisten) {
         unlisten();
       }

src/components/projects/ProjectLiveAgent.tsx

@@ -160,9 +160,11 @@ export default function ProjectLiveAgent() {
   useEffect(() => {
     if (!projectId) return;
 
+    let cancelled = false;
     let stop: (() => void) | null = null;
 
-    void (async () => {
+    const setup = async () => {
+      try {
         const [unlistenMessage, unlistenStarted, unlistenChunk, unlistenFinished, unlistenError] =
           await Promise.all([
             listen<LiveEventPayload>("live-agent-message", (event) => {
@@ -217,17 +219,34 @@ export default function ProjectLiveAgent() {
             }),
           ]);
 
-      stop = () => {
+        const cleanup = () => {
           unlistenMessage();
           unlistenStarted();
           unlistenChunk();
           unlistenFinished();
           unlistenError();
         };
-    })();
+
+        if (cancelled) {
+          cleanup();
+          return;
+        }
+
+        stop = cleanup;
+      } catch (err: unknown) {
+        if (!cancelled) {
+          setError(getErrorMessage(err));
+        }
+      }
+    };
+
+    void setup();
 
     return () => {
-      if (stop) stop();
+      cancelled = true;
+      if (stop) {
+        stop();
+      }
     };
   }, [projectId, selectedSessionId]);
 

src/components/projects/ProjectTasks.tsx

@@ -76,18 +76,31 @@ export default function ProjectTasks() {
 
   useEffect(() => {
     if (!projectId) return;
-    let stop: (() => void) | null = null;
+    let cancelled = false;
+    let unlisten: (() => void) | null = null;
 
-    void (async () => {
-      const unlisten = await listen<TaskEventPayload>("agent-task-updated", (event) => {
+    void listen<TaskEventPayload>("agent-task-updated", (event) => {
       if (event.payload.project_id !== projectId) return;
       void refresh();
+    })
+      .then((cleanup) => {
+        if (cancelled) {
+          cleanup();
+          return;
+        }
+        unlisten = cleanup;
+      })
+      .catch((err: unknown) => {
+        if (!cancelled) {
+          setError(getErrorMessage(err));
+        }
       });
-      stop = unlisten;
-    })();
 
     return () => {
-      if (stop) stop();
+      cancelled = true;
+      if (unlisten) {
+        unlisten();
+      }
     };
   }, [projectId]);