/**
 * Origin-politeness helpers for the anti-bot tier. Pure functions so they are
 * unit-testable without a network or a DB. The router uses these to translate a
 * rate-limit response into a bounded per-host backoff window and to avoid
 * re-hammering a host that is actively refusing us.
 */
/** Backoff applied to a 429 that carries no parseable Retry-After header. */
export declare const DEFAULT_BACKOFF_MS = 60000;
/**
 * Upper bound on any backoff window. A hostile or absurd Retry-After
 * ("99999") must not park a domain for hours — 5 minutes is the ceiling.
 */
export declare const MAX_BACKOFF_MS = 300000;
/**
 * Parse an HTTP `Retry-After` header into a delay in milliseconds relative to
 * `nowMs`. Supports both header forms:
 *  - delta-seconds integer (`"120"`) → `120_000`
 *  - HTTP-date (`"Wed, 21 Oct 2026 07:28:00 GMT"`) → `Date.parse(...) - nowMs`,
 *    floored at 0 so a stale/past date never yields a negative delay.
 * Returns null for an empty, missing, or unparseable value.
 */
export declare function parseRetryAfter(headerValue: string | undefined, nowMs: number): number | null;
/** Clamp a backoff delay into `[0, MAX_BACKOFF_MS]`. */
export declare function clampBackoffMs(ms: number): number;
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