import { Transport } from '@modelcontextprotocol/sdk/shared/transport.js';
import { type MessageExtraInfo, JSONRPCMessage } from '@modelcontextprotocol/sdk/types.js';
/**
 * Transport implementation that uses the browser's MessageChannel API for communication
 * between different browser contexts (iframes, workers, tabs, windows, etc.).
 */
export declare class BrowserContextTransport implements Transport {
    sessionId?: string;
    onmessage?: <T extends JSONRPCMessage>(message: T, extra?: MessageExtraInfo) => void;
    onerror?: (error: Error) => void;
    onclose?: () => void;
    private _port;
    private _started;
    private _closed;
    /**
     * Creates a new BrowserContextTransport using an existing MessagePort.
     *
     * @param { MessagePort } port The MessagePort to use for communication.
     */
    constructor(port: MessagePort);
    /**
     * Starts processing messages on the transport.
     * This starts the underlying MessagePort if it hasn't been started yet.
     *
     * @throws Error if the transport is already started or has been closed.
     */
    start(): Promise<void>;
    /**
     * Sends a JSON-RPC message over the MessagePort.
     *
     * @param { JSONRPCMessage } message The JSON-RPC message to send.
     * @throws Error if the transport is closed or the message cannot be sent.
     */
    send(message: JSONRPCMessage): Promise<void>;
    /**
     * Closes the MessagePort and marks the transport as closed.
     * This method will call onclose if it's defined.
     */
    close(): Promise<void>;
}