import type { FetchFn } from "./types.js";
/**
 * Configuration for the retry-on-429 fetch wrapper.
 */
export interface RetryFetchOptions {
    /**
     * Maximum number of retry attempts after a `429 Too Many Requests`.
     * @default 3
     */
    maxRetries?: number;
    /**
     * Delay schedule in milliseconds for each retry attempt (index-based).
     * If the server sends a `Retry-After` header, the *larger* of the
     * scheduled delay and the server hint is used.
     *
     * @default [1000, 2000, 3000]
     */
    delays?: number[];
    /**
     * Optional `AbortSignal` to cancel pending retries.
     * Already-in-flight fetch calls are also forwarded the signal.
     */
    signal?: AbortSignal;
    /**
     * Optional callback invoked before each retry wait.
     * Return `false` to cancel the retry loop immediately.
     */
    onRetry?: (attempt: number, delayMs: number, response: Response) => boolean | void;
}
/**
 * Wrap a `FetchFn` with automatic retry on HTTP 429 (Too Many Requests).
 *
 * - Retries up to `maxRetries` times (default 3).
 * - Uses a linear backoff of 1 s → 2 s → 3 s (configurable via `delays`).
 * - Respects the `Retry-After` header — uses `max(scheduled, server hint)`.
 * - Supports cancellation via `AbortSignal` or the `onRetry` callback.
 *
 * Usage:
 * ```ts
 * const fetchFn = retryFetch(globalThis.fetch, { signal: controller.signal });
 * const reader = new FhirResourceReader(baseUrl, "Patient", fetchFn);
 * ```
 */
export declare function retryFetch(inner: FetchFn, options?: RetryFetchOptions): FetchFn;
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