import { PwaUpdateOptions } from './types.js';
declare class PwaUpdateServiceImpl {
    private _listeners;
    private _options;
    private _registration?;
    private _waitingWorker?;
    private _active;
    private _applying;
    private _reloading;
    private _hadController;
    /**
     * Start watching the service-worker registration. Idempotent and SSR-safe;
     * a no-op when the browser has no service-worker support or the app ships
     * none. Called from `startInit` with defaults — an app that wants custom
     * options calls `activate(options)` **before** `startInit()` (the first
     * call wins, later calls are ignored).
     */
    activate(options?: PwaUpdateOptions): void;
    /** True when a new version is installed and waiting to take over. */
    get updateAvailable(): boolean;
    /** True between `applyUpdate()` and the reload it triggers. */
    get applying(): boolean;
    /**
     * Ask the browser to check for a new service worker now. Cheap and safe to
     * call at any time; failures (offline, transient network) are swallowed —
     * the next trigger simply tries again.
     */
    checkForUpdate(): Promise<void>;
    /**
     * Activate the waiting worker and reload once it has taken over. Returns
     * `false` when there is nothing to apply (or an apply is already running).
     *
     * The reload happens on `controllerchange`, not here — so it also fires
     * exactly once when another tab of the same app applies the update.
     */
    applyUpdate(): boolean;
    /**
     * Subscribe to update-state changes (update found, apply started).
     * @returns Unsubscribe function.
     */
    subscribe(callback: () => void): () => void;
    private _attach;
    private _handleUpdateFound;
    private _handleControllerChange;
    private _handleVisibilityChange;
    private _notifyListeners;
}
/** Singleton instance of the PWA update service. */
export declare const pwaUpdateService: PwaUpdateServiceImpl;
export {};
//# sourceMappingURL=PwaUpdateService.d.ts.map