/**
 * The phase timing behind an animated menu screen: closed → entering → open → exiting → closed. Pure
 * timing over an injected clock, so a React block can animate with CSS and still know exactly when an
 * exit finished and the screen may unmount. Reduced motion collapses every duration to zero instead
 * of skipping the state machine, so callers never branch on it.
 */
/** Where a menu screen is in its enter/exit animation. */
export type MenuTransitionPhase = "closed" | "enter" | "open" | "exit";
/** Durations and accessibility policy for one transition. */
export interface MenuTransitionConfig {
    /** Enter duration, ms. Default 220. */
    enterMs?: number;
    /** Exit duration, ms. Default 160. */
    exitMs?: number;
    /** Collapse both durations to zero (the accessibility "reduced motion" preference). */
    reducedMotion?: boolean;
}
/** Serializable phase state. */
export interface MenuTransitionSnapshot {
    phase: MenuTransitionPhase;
    /** Clock time (ms) the phase started. */
    since: number;
}
/** Observable enter/exit phase machine. */
export interface MenuTransition {
    state(): MenuTransitionSnapshot;
    /** Begin entering from closed/exit, or go straight to open when motion is off. No-op when entering/open. */
    open(now: number): void;
    /** Begin exiting from entering/open. No-op when already exiting/closed. */
    close(now: number): void;
    /** Advance the machine to `now`; entering → open and exiting → closed happen here. */
    tick(now: number): MenuTransitionSnapshot;
    subscribe(listener: () => void): () => void;
    snapshot(): MenuTransitionSnapshot;
    restore(snapshot: MenuTransitionSnapshot): void;
}
/** The enter and exit durations after reduced-motion is applied. */
export declare function menuTransitionDurations(config?: MenuTransitionConfig): {
    enter: number;
    exit: number;
};
/** How long the current phase lasts, in ms (0 for open/closed). */
export declare function menuTransitionPhaseMs(phase: MenuTransitionPhase, config?: MenuTransitionConfig): number;
/**
 * Create a {@link MenuTransition}. `open`/`close` start a phase; `tick` advances it once its duration
 * has elapsed. Nothing schedules timers here — the caller ticks from its animation loop or a timeout.
 *
 * @capability menu-transition enter/exit phase timing for an animated menu screen, with reduced-motion collapse and snapshot/restore
 */
export declare function createMenuTransition(config?: MenuTransitionConfig, initial?: MenuTransitionSnapshot): MenuTransition;