fix: harden generation task polling fallback

src/App.tsx

@@ -8,6 +8,7 @@ import ToastContainer from "./components/toast/ToastContainer";
 import { toast } from "./components/toast/toastStore";
 import { aiGenerationClient } from "./api/aiGenerationClient";
 import { keyServerClient } from "./api/keyServerClient";
+import { setUserMaxConcurrency } from "./api/generationConcurrency";
 import { notificationClient } from "./api/notificationClient";
 import {
   SERVER_SESSION_REPLACED_EVENT,
@@ -466,6 +467,7 @@ function App() {
   const clearAuthenticatedState = useCallback((options?: { resetView?: boolean }) => {
     clearAllUserStorage();
     clearSessionState();
+    setUserMaxConcurrency(null);
     setProjects([]);
     setProjectsLoaded(true);
     setUsage(emptyUsageSummary);
@@ -574,6 +576,7 @@ function App() {
       const nextSession = await keyServerClient.getCurrentSession();
       if (cancelled) return;
       setSession(nextSession);
+      setUserMaxConcurrency(nextSession?.user?.maxConcurrency);
       await hydrateAccountData(nextSession);
     };
 
@@ -606,6 +609,7 @@ function App() {
         if (cancelled) return;
         if (nextSession) {
           setSession(nextSession);
+          setUserMaxConcurrency(nextSession?.user?.maxConcurrency);
         } else {
           clearAuthenticatedState({ resetView: true });
         }
@@ -943,6 +947,7 @@ function App() {
     async (nextSession: WebUserSession) => {
       hideSessionReplaced();
       setSession(nextSession);
+      setUserMaxConcurrency(nextSession?.user?.maxConcurrency);
       await hydrateAccountData(nextSession);
 
       if (nextSession.user.email && !nextSession.user.emailVerified) {