/**
 * Provider retry-hint parsing — the transport seam for `Retry-After` and
 * the rate-limit header family (#186).
 *
 * A supplier that answers with a delay hint is telling the caller when to
 * come back; the shared executor already honours the parsed value as a
 * floor over its own backoff (`lib/execution.ts`). This module is the
 * producer end: Adapters hand the Response headers in where the status
 * map throws, and get back a millisecond number — or nothing.
 *
 * Sources, in precedence order (first PARSEABLE wins):
 *   1. `Retry-After` — RFC 9110 §10.2.1: `delay-seconds` (`1*DIGIT`, an
 *      integer — never fractional) or an HTTP-date.
 *   2. `X-RateLimit-Retry-After` — integer delta-seconds.
 *   3. `X-RateLimit-Reset` — SECONDS UNTIL RESET, relative (OpenAlex's
 *      documented semantic), not an epoch timestamp.
 *
 * Header VALUES never leave this module: callers receive a number only,
 * so provider-controlled text cannot reach an error message, a log, or
 * the public envelope. Anything unparseable — garbage, empty, negative,
 * non-integer, absent — contributes nothing and falls through to the
 * next source; nothing parseable yields `undefined`, which the Adapters
 * turn into an OMITTED error field (byte-identical error path).
 */
/** Minimal header surface — a fetch `Headers` satisfies it directly. */
export interface RetryHintHeaders {
    get?(name: string): string | null;
}
/**
 * Read the first parseable retry hint off a Response's headers.
 *
 * `now` is injectable so the HTTP-date form is deterministic under test;
 * production callers take the default `Date.now`.
 */
export declare function parseRetryAfterHintMs(headers: RetryHintHeaders | null | undefined, now?: () => number): number | undefined;
/**
 * #186 ocr review finding: brave and jina adapters carried identical
 * read-and-wrap helpers — hoisted here so the forwarding rule changes in
 * exactly one place.
 */
export declare function retryHintOptionsFromError(error: unknown): {
    retryAfterMs?: number;
};
/**
 * Error-constructor options carrying the hint, or NOTHING when there was
 * no parseable hint — the options object omits the key entirely, so nothing
 * is attached and the error message and stdout envelope stay byte-identical.
 * (The instance itself still materializes an own `retryAfterMs: undefined`
 * — the constructor's standing idiom, same as `statusCode`/`help`.)
 */
export declare function retryHintOptions(retryAfterMs: number | undefined): {
    retryAfterMs?: number;
};
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