/**
 * @module
 * RetryTransport — decorator that wraps any sently channel transport
 * and retries failed sends with configurable backoff.
 * Works with email, SMS, WhatsApp, and push transports.
 *
 * @example
 * ```ts
 * import { RetryTransport } from 'sently/transports/retry'
 * import { ResendTransport } from 'sently/transports/resend'
 *
 * const transport = new RetryTransport(
 *   new ResendTransport({ apiKey }),
 *   { maxAttempts: 3, backoff: 'exponential', retryOn: [429, 503] }
 * )
 * ```
 */
import type { DecoratedTransport } from "../core/decorated-transport.js";
import type { MailOptions, RetryConfig, SendResult, VerifyResult } from "../core/types.js";
/**
 * Decorator transport that retries failed sends with configurable backoff.
 * Defaults preserve email {@link Transport} compatibility.
 */
export declare class RetryTransport<TOptions = MailOptions, TResult = SendResult> implements DecoratedTransport<TOptions, TResult> {
    /** Transport that performs the actual send on each attempt. */
    private readonly inner;
    /** Injectable sleep function for testing backoff timing. */
    private readonly _sleep;
    readonly provider = "retry";
    /** Maximum send attempts including the initial try. */
    private readonly maxAttempts;
    /** Backoff strategy between retries. */
    private readonly backoff;
    /** Base delay in milliseconds before the first retry. */
    private readonly baseDelay;
    /** HTTP status codes that trigger a retry. */
    private readonly retryOn;
    /** Optional callback invoked before each retry attempt. */
    private readonly onRetry;
    /** Additional onRetry callback wired by sender lifecycle hooks per send. */
    private mailerOnRetry;
    /** Wraps an inner transport with retry logic and optional backoff configuration. */
    constructor(
    /** Transport that performs the actual send on each attempt. */
    inner: DecoratedTransport<TOptions, TResult>, config?: RetryConfig, 
    /** Injectable sleep function for testing backoff timing. */
    _sleep?: (ms: number) => Promise<void>);
    /**
     * Register a per-send onRetry callback from sender lifecycle hooks.
     * Do not share one {@link RetryTransport} across multiple senders — the last
     * `setMailerOnRetry` wins; overwriting an active callback logs a dev warning.
     * @internal Cleared after each send.
     */
    setMailerOnRetry(callback: RetryConfig["onRetry"] | undefined): void;
    /** Sends with retries according to configured backoff and retry rules. */
    send(options: TOptions): Promise<TResult>;
    /** Delegates to the inner transport verify or returns a default success result. */
    verify(): Promise<VerifyResult>;
    /** Delegates close to the inner transport if available. */
    close(): Promise<void>;
    /** Delegates batch sends to the inner transport when available. */
    sendBatch(messages: TOptions[]): Promise<TResult[]>;
}