fix(desktop): cache ads across refresh failures

apps/desktop/src/shell/AppLayout.tsx

@@ -6,6 +6,7 @@ import cursorIconUrl from "../shared/assets/icons/cursor.svg";
 import { api } from "../shared/api";
 import { AdMenu } from "./ads/AdMenu";
 import { FloatingAd } from "./ads/FloatingAd";
+import { loadCachedAds, saveCachedAds } from "./ads/cache";
 import { AdActionType, type AdAction, type AdSlot } from "./ads/types";
 import { PageLayout } from "./layout/PageLayout";
 import { Card } from "../shared/ui/Card";
@@ -50,7 +51,7 @@ export function AppLayout() {
   const location = useLocation();
   const [leftActionTarget, setLeftActionTarget] = useState<HTMLDivElement | null>(null);
   const [rightActionTarget, setRightActionTarget] = useState<HTMLDivElement | null>(null);
-  const [ads, setAds] = useState<AdSlot[]>([]);
+  const [ads, setAds] = useState<AdSlot[]>(() => loadCachedAds());
   const [activeAd, setActiveAd] = useState<AdSlot | null>(null);
   const [dismissCandidate, setDismissCandidate] = useState<AdSlot | null>(null);
   const [dismissReason, setDismissReason] = useState("");
@@ -98,6 +99,8 @@ export function AppLayout() {
     let disposed = false;
     let pending = false;
     let lastRequestedAt = 0;
+    setAds(loadCachedAds());
+    setActiveAd(null);
     const refreshAds = () => {
       const now = Date.now();
       if (pending || now - lastRequestedAt < 10_000) return;
@@ -105,6 +108,7 @@ export function AppLayout() {
       lastRequestedAt = now;
       void api.ads(dismissedAdIdsRef.current, locale)
         .then((runtime) => {
+          saveCachedAds(runtime.slots);
           if (disposed) return;
           setAds(runtime.slots);
           setActiveAd((current) => current
@@ -112,9 +116,7 @@ export function AppLayout() {
             : null);
         })
         .catch(() => {
-          if (disposed) return;
-          setAds([]);
-          setActiveAd(null);
+          // Keep the current ads and local cache available when refreshing fails.
         })
         .finally(() => { pending = false; });
     };

apps/desktop/src/shell/ads/cache.ts

@@ -0,0 +1,21 @@
+import type { AdSlot } from "./types";
+
+const adCacheStorageKey = "cursor-byok:ad-runtime";
+
+export function loadCachedAds(): AdSlot[] {
+  try {
+    const value: unknown = JSON.parse(localStorage.getItem(adCacheStorageKey) ?? "null");
+    if (!value || typeof value !== "object" || !Array.isArray((value as { slots?: unknown }).slots)) return [];
+    return (value as { slots: AdSlot[] }).slots;
+  } catch {
+    return [];
+  }
+}
+
+export function saveCachedAds(slots: AdSlot[]): void {
+  try {
+    localStorage.setItem(adCacheStorageKey, JSON.stringify({ slots }));
+  } catch {
+    // The current session still uses the fetched ads when storage is unavailable.
+  }
+}