import type { Checkpoint, Mission, WorkerInstanceState } from './types.js';
import type { EventBus } from './event-bus.js';
import type { Logger } from './types.js';
export declare class CheckpointEngine {
    private eventBus;
    private logger;
    private dir;
    private maxPerMission;
    constructor(eventBus: EventBus, logger: Logger, storageDir?: string);
    setMaxPerMission(n: number): void;
    save(mission: Mission, workerStates: WorkerInstanceState[], reason: Checkpoint['reason']): Promise<Checkpoint>;
    private pruneMission;
    load(missionId: string, checkpointId: string): Checkpoint | undefined;
    latest(missionId: string): Checkpoint | undefined;
    list(missionId: string): Checkpoint[];
    purge(missionId: string): number;
}