/**
 * Background cleanup task for expired checkpoints.
 *
 * Runs periodically to delete checkpoints that have passed their TTL,
 * keeping the storage clean without manual intervention.
 */
import type { CheckpointStorage } from './types';
/**
 * Options for checkpoint cleanup task.
 */
export interface CheckpointCleanupOptions {
    /** Interval between cleanup runs in milliseconds. Default: 1 hour */
    intervalMs?: number;
}
/**
 * Background task for TTL-based checkpoint cleanup.
 *
 * Usage:
 * ```typescript
 * const cleanup = new CheckpointCleanupTask(storage);
 * cleanup.start(); // Begins periodic cleanup
 * cleanup.stop();  // Stops cleanup (call on shutdown)
 * ```
 */
export declare class CheckpointCleanupTask {
    private storage;
    private intervalMs;
    private timer?;
    private running;
    /** Default cleanup interval: 1 hour in milliseconds */
    static readonly DEFAULT_INTERVAL_MS = 3600000;
    constructor(storage: CheckpointStorage, options?: CheckpointCleanupOptions);
    /**
     * Start the periodic cleanup task.
     * Safe to call multiple times (no-op if already running).
     */
    start(): void;
    /**
     * Stop the periodic cleanup task.
     */
    stop(): void;
    /**
     * Run cleanup once (can be called manually or scheduled).
     * Returns number of deleted checkpoints.
     */
    runOnce(): Promise<number>;
    /**
     * Check if the task is currently running.
     */
    isRunning(): boolean;
    private runCleanup;
}
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