/**
 * Heartbeat wake scheduler — triggers ad-hoc heartbeat runs outside the regular interval.
 *
 * When external events (incoming messages, cron fires, system events) need the koi
 * to wake up and process immediately, they call {@link requestHeartbeatNow}. This module
 * coalesces rapid-fire requests (250ms window) and retries with exponential backoff
 * (1s → 30s) if the heartbeat runner is busy or fails.
 *
 * Only one heartbeat runs at a time. Requests that arrive while one is in-flight
 * are queued and coalesced into the next run.
 *
 * @module
 */
/** Result of a single heartbeat execution. */
export type HeartbeatRunResult = {
    status: "ran";
    durationMs: number;
} | {
    status: "skipped";
    reason: string;
} | {
    status: "failed";
    reason: string;
};
export type HeartbeatWakeHandler = (opts: {
    reason?: string;
}) => Promise<HeartbeatRunResult>;
export declare function setHeartbeatWakeHandler(next: HeartbeatWakeHandler | null): void;
export declare function requestHeartbeatNow(opts?: {
    reason?: string;
    coalesceMs?: number;
}): void;
export declare function hasHeartbeatWakeHandler(): boolean;
export declare function hasPendingHeartbeatWake(): boolean;