import type { Timestamp } from './types';
/**
 * Ensures that the input timestamp object has both epoch and performance.now() time.
 * If no input is provided, it generates a new timestamp with the current time.
 *
 * why store both timestamps?:
 * - epoch time: for reporting absolute time / correlating with backends
 * - durations: for calculating durations between two timestamps, performance.now() time makes more sense
 * - both are needed to correctly calculate a drift-adjusted epoch time
 *
 * @param input - Partial timestamp object that may contain either epoch or now or both.
 * @returns Full timestamp object with both epoch and performance.now() time.
 */
export declare const ensureTimestamp: (input?: Partial<Timestamp>) => Timestamp;
/**
 * Why do we need to account for drift?
 * - monotonic clock (performance.now()) is not guaranteed to be in sync with wall clock time (Date.now())
 * - Earth’s rotation speed is not constant
 * - browser bugs cause the monotonic clock to not tick when the computer is asleep or when the process is throttled
 * @see
 * - https://github.com/w3c/performance-timeline/issues/206
 * - https://dev.to/noamr/when-a-millisecond-is-not-a-millisecond-3h6
 * - https://issues.chromium.org/issues/41450546
 */
export declare function getEpochCorrectedForDrift({ epoch, now }: Timestamp): number;
export declare const adjustTimestampBy: (timestamp: Timestamp, adjustment: number) => {
    epoch: number;
    now: number;
};