/** F10 (ENG-388) — the overlay's remembered conversation. One id per origin
 *  (localStorage scoping, same rationale as discoverability.ts): the wire is
 *  principal-scoped and useVendoThread self-heals a stale or foreign id to a
 *  fresh thread, so persisting the bare id is safe. Degraded environments
 *  (SSR, sandboxed iframe, blocked or full storage) read as "nothing
 *  remembered" and writes stay silent. */
/** The remembered conversation id, when one is stored and well formed. */
export declare function lastThreadId(): string | undefined;
/** Remember the conversation. Best-effort: a failed write stays silent. */
export declare function rememberThread(threadId: string): void;
/** Forget the remembered conversation (an explicit fresh start). */
export declare function forgetThread(): void;