/**
 * When a failed piece of deferred work may be tried again.
 *
 * Shared by the cache-purge queue and the webhook queue because both answer the *same* question —
 * "the five-minute sweep is the only thing that will pick this up, so how many sweeps should it
 * skip" — and an answer tuned against that interval is not a property of either kind of work. Two
 * copies would be two things to change and one to forget.
 *
 * That is the only thing they share. The queues themselves stay separate for the reasons
 * `0033_webhooks` sets out: they differ on durability, on their columns, and on whether a screen
 * reads them.
 */
/** Backoff in minutes, indexed by attempts already made. The last entry repeats. */
export declare const RETRY_BACKOFF_MINUTES: number[];
/**
 * The moment a row with this many failures behind it becomes due.
 *
 * Zero for the first entry: something queued because an attempt just failed should be eligible on
 * the next sweep rather than waiting out a delay it has already served.
 */
export declare function nextRetryAt(attempts: number, from?: number): string;