/** Bubbling/composed events — `ds-shell-app` and `ds-bar-nav` coordinate during width motion. */
export declare const CHROME_TRANSITION_START = "dsChromeTransitionStart";
export declare const CHROME_TRANSITION_END = "dsChromeTransitionEnd";
export type ChromeTransitionSource = 'panel-nav' | 'panel-tools';
export interface ChromeTransitionDetail {
    source: ChromeTransitionSource;
    /** Panel-tools drawer motion direction; omitted for panel-nav. */
    phase?: 'opening' | 'closing';
}
/** Reference-counted gate — used while panel-nav width is transitioning. */
export declare class ChromeTransitionDepth {
    private depth;
    enter(): void;
    exit(): void;
    get isActive(): boolean;
}
/** Idempotent gate for one physical chrome surface.
 * Duplicate start notifications still require only one matching end. */
export declare class ChromeTransitionGate {
    private active;
    enter(): void;
    exit(): void;
    get isActive(): boolean;
}
export interface RafCoalescer {
    schedule(): void;
    cancel(): void;
}
/** Coalesce bursty layout work (ResizeObserver, prop churn) to one callback per frame. */
export declare function createRafCoalescer(onFrame: () => void): RafCoalescer;
export declare function readChromeTransitionSource(event: Event): ChromeTransitionSource | undefined;
export declare function readChromeTransitionPhase(event: Event): ChromeTransitionDetail['phase'];
//# sourceMappingURL=chrome-transition.d.ts.map