/** The current selection for a sync key, or `undefined` if none is stored. */
export declare function syncedValue(key: string): string | undefined;
/** Record a selection for a sync key and persist it. Client-only. */
export declare function setSyncedValue(key: string, value: string): void;
/**
 * Load a key's persisted selection into the reactive store, once, on the
 * client. Called from an effect (after hydration) so the first client render
 * still matches the server's default and there is no hydration mismatch.
 */
export declare function hydrateSyncedValue(key: string): void;