fix: surface reviewer response failures

frontend/src/shell/AppShell.tsx

@@ -372,12 +372,29 @@ export function AppShell() {
   // condition the final workflow step — which ends with no follow-up gate — would
   // leave the working state on forever.
   const pendingWidget = useSessionStore((s) => s.pendingWidget);
+  const sessionToasts = useSessionStore((s) => s.toasts);
   const resetSession = useSessionStore((s) => s.resetSession);
   const recordLifecycle = useSessionStore((s) => s.recordLifecycle);
   const setPhase = useSessionStore((s) => s.setPhase);
   const setAgentActive = useSessionStore((s) => s.setAgentActive);
   const lastSystemEvent = useSessionStore((s) => s.lastSystemEvent);
   const agentActive = useSessionStore((s) => s.agentActive);
+  const deliveredToastCountRef = useRef(0);
+
+  useEffect(() => {
+    if (sessionToasts.length < deliveredToastCountRef.current) {
+      deliveredToastCountRef.current = 0;
+    }
+
+    for (const notification of sessionToasts.slice(deliveredToastCountRef.current)) {
+      if (notification.level === "error") toast.error(notification.text);
+      else if (notification.level === "success") toast.success(notification.text);
+      else if (notification.level === "warning") toast.warning(notification.text);
+      else toast.info(notification.text);
+    }
+
+    deliveredToastCountRef.current = sessionToasts.length;
+  }, [sessionToasts]);
   const sessionViewOpen = Boolean(activeSessionId) || creatingSession;
   const working = sessionViewOpen && !pendingWidget && agentActive;
   // The workflow bar runs only while the harness works, not while a finalized