export interface TaskQueueOptions {
    /** Number of tasks processed concurrently. */
    readonly concurrency: number;
    /** Max total attempts per task (1 = no retries, 3 = initial + 2 retries). */
    readonly maxAttempts: number;
    /** Base delay for exponential backoff, in ms. Default 1000. */
    readonly backoffBaseMs?: number;
    /** Max backoff cap, in ms. Default 30_000. */
    readonly backoffMaxMs?: number;
}
export interface TaskQueueStats {
    readonly total: number;
    readonly pending: number;
    readonly running: number;
    readonly done: number;
    readonly failed: number;
}
export interface TaskQueue {
    readonly add: (task: {
        readonly id: string;
        readonly [key: string]: unknown;
    }) => void;
    readonly process: (handler: (task: Record<string, unknown>) => Promise<void>) => Promise<void>;
    readonly stats: () => TaskQueueStats;
    readonly close: () => void;
}
export declare function makeTaskQueue(dbPath: string, options: TaskQueueOptions): TaskQueue;