ui: request persistent storage on startup (#31299)

Ask the browser to keep IndexedDB and localStorage data under storage
pressure, so conversations and settings are less likely to be evicted.

Assisted-by: Claude (Opus 5.5 Medium)

tools/ui/src/lib/stores/init.ts

@@ -11,12 +11,25 @@ import { validateApiKey } from '$lib/utils/api-key-validation';
 
 let startup: Promise<void> | null = null;
 
+/** Ask the browser not to evict conversations and settings under storage pressure, best effort. */
+async function requestPersistentStorage(): Promise<void> {
+	try {
+		if (!navigator.storage?.persist || (await navigator.storage.persisted())) return;
+
+		await navigator.storage.persist();
+	} catch {
+		// unsupported or denied, storage stays best-effort
+	}
+}
+
 export function initStores(): Promise<void> {
 	if (!browser) return Promise.resolve();
 
 	startup ??= (async () => {
 		await MigrationService.runAllMigrations();
 
+		void requestPersistentStorage();
+
 		settingsStore.initialize();
 		permissionsStore.initialize();
 		toolsStore.initialize();