/**
 * Express-based A2A server that exposes a Strands Agent as an A2A-compliant HTTP endpoint.
 *
 * Separated from the base {@link A2AServer} so that importing the core A2A module
 * does not pull in Express as a dependency, keeping it browser-compatible.
 *
 * The A2A protocol is experimental, so breaking changes in the underlying SDK
 * may require breaking changes in this module.
 */
import { type Router } from 'express';
import { UserBuilder } from '@a2a-js/sdk/server/express';
import { A2AServer, type A2AServerConfig } from './server.js';
/**
 * Configuration options for creating an A2AExpressServer.
 */
export interface A2AExpressServerConfig extends A2AServerConfig {
    /** Host to bind the server to (default: '127.0.0.1') */
    host?: string;
    /** Port to listen on (default: 9000) */
    port?: number;
    /** User builder for authentication (default: no authentication) */
    userBuilder?: UserBuilder;
}
/**
 * Express-based A2A server implementation.
 *
 * Provides two usage modes:
 * - **Standalone**: Call {@link serve} to start a self-contained HTTP server.
 * - **Middleware**: Call {@link createMiddleware} to get an Express Router that
 *   can be mounted in an existing Express application.
 */
export declare class A2AExpressServer extends A2AServer {
    private _host;
    private _port;
    private _userBuilder;
    /**
     * Creates a new A2AExpressServer.
     *
     * @param config - Configuration for the server
     */
    constructor(config: A2AExpressServerConfig);
    /**
     * Returns the port the server is configured to listen on.
     * After `serve()` resolves, this reflects the actual bound port
     * (useful when configured with port 0 for OS-assigned ports).
     */
    get port(): number;
    /**
     * Creates an Express Router middleware for the A2A endpoints.
     *
     * Mounts:
     * - `GET /.well-known/agent-card.json` — Returns the agent card
     * - `POST /` — Handles A2A JSON-RPC requests
     *
     * @returns An Express Router with A2A endpoints mounted
     */
    createMiddleware(): Router;
    /**
     * Starts the HTTP server and begins listening for A2A requests.
     *
     * @param options - Optional server options
     */
    serve(options?: {
        signal?: AbortSignal;
    }): Promise<void>;
}
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