export type OutboxAwaitable<T> = T | Promise<T>;
export interface DurableOutboxEntry {
    attempts: number;
}
export interface DurableOutboxFailure {
    message: string;
    retryAfterMs?: number;
}
export interface DurableOutboxRetry {
    attempts: number;
    nextTryAt: number;
    error: string;
}
export interface DurableOutboxPolicy {
    pollMs: number;
    baseDelayMs: number;
    maxDelayMs: number;
    maxAttempts: number;
}
export interface DurableOutboxStore<Entry extends DurableOutboxEntry, Delivery> {
    due(now: number): OutboxAwaitable<readonly Entry[]>;
    hasPending(): OutboxAwaitable<boolean>;
    acknowledge(entry: Entry, delivery: Delivery): OutboxAwaitable<void>;
    discard(entry: Entry): OutboxAwaitable<void>;
    retry(entry: Entry, retry: DurableOutboxRetry): OutboxAwaitable<void>;
    deadLetter(entry: Entry, retry: Omit<DurableOutboxRetry, "nextTryAt">): OutboxAwaitable<void>;
}
export interface DurableOutboxWorkerOptions<Entry extends DurableOutboxEntry, Delivery, Timer = ReturnType<typeof setTimeout>> {
    store: DurableOutboxStore<Entry, Delivery>;
    deliver(entry: Entry): Promise<Delivery>;
    classifyError(error: unknown): DurableOutboxFailure;
    policy: DurableOutboxPolicy;
    shouldDiscard?(entry: Entry): OutboxAwaitable<boolean>;
    onEntryStart?(entry: Entry): void;
    onEntryEnd?(entry: Entry): void;
    onDeadLetter?(entry: Entry, retry: Omit<DurableOutboxRetry, "nextTryAt">): void;
    onError?(error: unknown): void;
    now?: () => number;
    schedule?: (callback: () => void, delayMs: number) => Timer;
    cancel?: (timer: Timer) => void;
}
export interface DurableOutboxWorker {
    start(): void;
    wake(): void;
    flush(): Promise<void>;
    stop(): void;
}
export declare function exponentialOutboxBackoff(attempts: number, policy: Pick<DurableOutboxPolicy, "baseDelayMs" | "maxDelayMs">): number;
/** Drive a durable store without coupling retry policy to a transport or database. */
export declare function createDurableOutboxWorker<Entry extends DurableOutboxEntry, Delivery, Timer = ReturnType<typeof setTimeout>>(options: DurableOutboxWorkerOptions<Entry, Delivery, Timer>): DurableOutboxWorker;
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