/**
 * Transient-failure retry backoff (1.38, §10 N1/N2).
 *
 * Two production must-haves that the plain `base * 2^attempt` backoff lacked:
 * - **Full jitter** — `random(0, min(cap, base*2^attempt))` — so many clients retrying after the same
 *   429 don't synchronize into a thundering herd that worsens the outage they're recovering from.
 * - **Respect `Retry-After`** — when the server tells us how long to wait (429/503), honor it as a
 *   floor: `wait = max(retryAfter, jittered)`. Retrying earlier just gets rejected again.
 */
/** Parse a `Retry-After` header (delta-seconds or HTTP-date) to ms; undefined if absent/unparseable. */
export declare function parseRetryAfter(res: Response | undefined): number | undefined;
/**
 * Backoff (ms) for retry `attempt` (0-based) of a transient failure. Full jitter over exponential
 * backoff, capped; when the response carried `Retry-After`, that is honored as a lower bound.
 * `rand` is injectable for deterministic tests.
 */
export declare function retryBackoffMs(baseDelayMs: number, attempt: number, res?: Response, rand?: () => number): number;
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