/**
 * Notices when the page wakes from a suspension it could not observe: a
 * laptop sleep, a frozen tab, or a network that came back. Live streams on a
 * page that slept usually died with it, while the hidden-tab signal never
 * fired (or its grace timer could not run), so they would otherwise wait for
 * a heartbeat timeout before reconnecting.
 *
 * Detection: a light timer compares wall-clock time between ticks (timers do
 * not run while the machine sleeps, but the wall clock moves on), checked
 * again when the page becomes visible, plus the `online`, `resume` (Page
 * Lifecycle) and bfcache `pageshow` events. One shared detector serves every
 * subscriber and stops with the last one.
 */
/** How often the wall clock is sampled while anyone listens. */
export declare const PAGE_WAKE_CHECK_INTERVAL_MS = 2000;
/** A tick this long after the previous one means the page was suspended. */
export declare const PAGE_WAKE_GAP_MS = 15000;
type PageWakeListener = () => void;
/** Call `listener` on every detected wake; returns the unsubscribe. */
export declare function subscribePageWake(listener: PageWakeListener): () => void;
export {};