/**
 * Exactly-once request close hooks shared across adapters.
 *
 * Fired on:
 * - host request/response close/finish (when available)
 * - response send completion via finishResponseSend
 *
 * Token is typically the VextRequest object for the active request.
 */
export declare function addRequestCloseHandler(token: object, handler: () => void): void;
export declare function fireRequestCloseHandlers(token: object): void;