/**
 * Focus Collector — tracks tab/window focus changes and visibility.
 * Captures: blur/focus transitions, total focused/unfocused time, switch count.
 */
import type { TelemetryEvent } from '../types.js';
export declare function startFocusTracking(push: (event: TelemetryEvent) => void): void;
export declare function stopFocusTracking(): void;
export declare function getFocusStats(): {
    switchCount: number;
    totalFocused: number;
    totalUnfocused: number;
};
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