import { MessageHandler, MessageType, MessengerOptions } from './types.ts';
/**
 * `Messenger` abstracts away the raw `window.postMessage` / `addEventListener`
 * API and enforces:
 *  - Typed send API.
 */
export declare class Messenger {
    private readonly targetWindow;
    private readonly targetOrigin;
    private readonly allowedOrigin;
    /** Map of message-type → set of handlers registered via `.on()`. */
    private readonly handlers;
    /** Bound reference kept so we can remove the exact same listener in `destroy()`. */
    private readonly boundListener;
    constructor(options: MessengerOptions);
    /**
     * Send a typed message **to** the widget iframe.
     *
     * @param type  - One of the protocol's `MessageType` values.
     * @param data  - Arbitrary payload; typed by the caller.
     */
    send<T>(type: MessageType, data: T): void;
    /**
     * Subscribe to a specific message type **from** the widget.
     * Returns an unsubscribe function for convenience.
     *
     * @param type    - The `MessageType` to listen for.
     * @param handler - Callback invoked with the `data` field of the payload.
     */
    on<T>(type: MessageType, handler: MessageHandler<T>): () => void;
    /**
     * Remove all registered handlers and the window-level `message` listener.
     * Must be called during SDK teardown to prevent memory leaks.
     */
    destroy(): void;
    private handleMessage;
}