/**
 * Clock abstraction for deterministic testing.
 * FakeClock allows complete control over time in tests.
 * RealClock is a passthrough to native timers (for production).
 */
/**
 * Clock interface: abstracts setTimeout, setInterval, Date.now().
 * Used by features like heartbeat, limits, and test utilities.
 */
export interface Clock {
    /**
     * Schedule a function to run after delay (milliseconds).
     * Returns a timer ID that can be passed to clearTimeout.
     */
    setTimeout(fn: () => void, ms: number): unknown;
    /**
     * Clear a scheduled timeout.
     */
    clearTimeout(id: unknown): void;
    /**
     * Schedule a function to repeat every interval (milliseconds).
     * Returns a timer ID that can be passed to clearInterval.
     */
    setInterval(fn: () => void, ms: number): unknown;
    /**
     * Clear a scheduled interval.
     */
    clearInterval(id: unknown): void;
    /**
     * Current time in milliseconds since epoch (or fake clock start).
     */
    now(): number;
}
/**
 * Fake clock for deterministic testing.
 * Supports full control over time progression and task scheduling.
 *
 * Usage:
 *   const clock = new FakeClock();
 *   await clock.tick(30_000); // Advance time 30s and run due timers
 *   await clock.flush();      // Flush microtasks without advancing time
 */
export declare class FakeClock implements Clock {
    private now_;
    private timers;
    private nextId;
    private queue;
    /**
     * Get current fake time.
     */
    now(): number;
    setTimeout(fn: () => void, ms: number): unknown;
    clearTimeout(id: unknown): void;
    setInterval(fn: () => void, ms: number): unknown;
    clearInterval(id: unknown): void;
    /**
     * Advance time by ms milliseconds and run all due timers.
     * Flushes microtasks between timer runs.
     * Repeats until no more timers are due.
     */
    tick(ms: number): Promise<void>;
    /**
     * Flush pending microtasks without advancing time.
     * Useful after inbound messages to settle promise chains.
     */
    flush(): Promise<void>;
    /**
     * Reset clock: clear all timers and set time to 0.
     */
    reset(): void;
    /**
     * Get list of pending timers (for debugging/leak detection).
     */
    pendingTimers(): {
        id: unknown;
        dueAt: number;
        isInterval: boolean;
    }[];
    private enqueueTimer;
    private runDueTimers;
}
/**
 * System clock: passthrough to native timers.
 * Use for production or when you don't need deterministic testing.
 */
export declare class SystemClock implements Clock {
    setTimeout(fn: () => void, ms: number): unknown;
    clearTimeout(id: unknown): void;
    setInterval(fn: () => void, ms: number): unknown;
    clearInterval(id: unknown): void;
    now(): number;
}
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