import type { Transport, JSONRPCMessage } from '@modelcontextprotocol/server';
import type { Request, Response } from 'express';
/**
 * A custom Server Transport that implements the Legacy SSE (MCP 2024-11-05) protocol.
 * This is required because the official @modelcontextprotocol/server v2 package
 * removed stateful SSEServerTransport in favor of Streamable HTTP (MCP 2025-03-26).
 * This transport allows older clients (like SSEClientTransport) to connect using
 * `GET /sse` followed by `POST /messages`.
 */
export declare class LegacySSEServerTransport implements Transport {
    private messagesEndpoint;
    private res;
    sessionId: string;
    onclose?: () => void;
    onerror?: (error: Error) => void;
    onmessage?: (message: JSONRPCMessage) => void;
    constructor(messagesEndpoint: string, sessionId?: string);
    start(): Promise<void>;
    close(): Promise<void>;
    send(message: JSONRPCMessage): Promise<void>;
    /**
     * Handles the initial GET request to establish the SSE stream.
     */
    handleSseRequest(req: Request, res: Response): void;
    /**
     * Handles incoming POST requests containing JSON-RPC messages.
     */
    handlePostMessage(req: Request, res: Response): void;
}
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