/**
 * Deterministic virtual clock for testing durable workflows.
 *
 * Does NOT monkey-patch global timers. Instead, provides an explicit
 * `now` property and a `schedule` method for registering timer callbacks
 * that fire when virtual time is advanced past their target.
 *
 * @module testing/time-control
 */
import type { Duration } from '../core/types';
/**
 * Deterministic virtual clock for testing durable workflows that depend on
 * time-based behaviour (timers, delays, scheduling).
 *
 * Does NOT monkey-patch global timers.  Instead, provides an explicit `now`
 * property and an `advance` method that fires registered callbacks in
 * chronological order as virtual time moves forward.  Use this inside a
 * {@link TestEngine} to write fully deterministic timer tests.
 *
 * @example
 * ```ts
 * import { TimeControl } from '@lostgradient/weft/testing';
 *
 * const clock = new TimeControl(0);
 * let fired = false;
 *
 * clock.schedule(5_000, () => {
 *   fired = true;
 * });
 *
 * await clock.advance('5s');
 * console.log(fired);   // true
 * console.log(clock.now); // 5000
 * ```
 */
export declare class TimeControl {
    #private;
    constructor(startTime?: number);
    /** Current virtual time in milliseconds since epoch. */
    get now(): number;
    /**
     * Advance time by duration. Fires all timers that fall within the
     * window, in chronological order.
     */
    advance(duration: Duration): Promise<void>;
    /** Advance time to a specific timestamp. Throws if in the past. */
    advanceTo(timestamp: number): Promise<void>;
    /**
     * Schedule a timer callback at a specific virtual time.
     * Returns a cancel function.
     */
    schedule(fireAt: number, callback: () => void | Promise<void>): () => void;
    /** Number of pending (non-cancelled, not-yet-fired) timers. */
    get pendingTimerCount(): number;
    /** Peek at the next timer's fire time. */
    get nextTimerAt(): number | undefined;
    /** Reset to initial state. */
    reset(startTime?: number): void;
}