/** Grace period before treating popup.closed as user cancellation (COOP can sever opener early). */
export declare const POPUP_CLOSED_CANCEL_GRACE_MS = 2500;
export type PopupClosePollState = {
    graceStartedAtMs: number | null;
};
export declare function nextPopupClosePollState(closed: boolean, state: PopupClosePollState, nowMs: number, graceMs?: number): {
    state: PopupClosePollState;
    shouldCancel: boolean;
};