import type { Clock } from "./types.js";
export declare function systemClock(): Clock;
export declare function fakeClock(start?: Date): Clock & {
    advance(ms: number): void;
    set(next: Date): void;
};
export declare function toIso(clock: Clock): string;
export declare function addHours(iso: string, hours: number): string;
export declare function isAtOrAfter(iso: string, deadlineIso: string): boolean;