/**
 * Format the gap between `then` (any of: epoch ms, epoch sec, ISO
 * string, or Date) and `now` (default = current time, epoch ms) as a
 * short human label.
 *
 *   < 60s            → "just now"
 *   < 60min          → "5min ago"
 *   < 24h            → "3h ago"
 *   < 30d            → "7d ago"
 *   < 12 months      → "4mo ago"
 *   otherwise        → "2y ago"
 *
 * Returns 'unknown' on invalid input rather than throwing — these are
 * presentation labels, not security-critical data.
 *
 * Future-dated `then` (e.g. clock skew) yields 'just now' rather than
 * negative ages.
 */
export declare function formatAge(then: number | string | Date | null | undefined, now?: number): string;
//# sourceMappingURL=format-age.d.ts.map