/**
 * Maintenance signal — notifies active poll loops immediately when the
 * maintenance flag file is written, so they can return the maintenance
 * response before the server process is killed.
 *
 * Uses fs.watch() on the data directory to detect flag creation without
 * requiring callers to poll.  The exported emitMaintenanceSignal() is
 * available for manual/test triggering.
 */
/** Close the filesystem watcher (call during shutdown). */
export declare function closeMaintenanceWatcher(): void;
/**
 * Record that a thread observed the maintenance flag.
 * @returns true on the FIRST observation this cycle (for one-shot side effects
 *          like a Telegram notification), false on repeat observations.
 */
export declare function markMaintenanceObserved(threadId: number): boolean;
/** Whether a thread has already observed the maintenance flag this cycle. */
export declare function hasObservedMaintenance(threadId: number): boolean;
/** Reset the observed set (call when the maintenance flag is cleared). */
export declare function clearMaintenanceObserved(): void;
/** Manually fire the maintenance signal (e.g. from tests or from code that
 *  writes the flag directly without going through the file system watcher). */
export declare function emitMaintenanceSignal(): void;
/**
 * Subscribe to the maintenance signal.
 * @returns An unsubscribe function — call it to remove the listener.
 */
export declare function onMaintenanceSignal(cb: () => void): () => void;
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