Class HttpMcpClient

packages/agent-core/src/mcp/client-http.ts:45–185

 * OAuth providers are attached separately by the connection manager.
 */
export class HttpMcpClient implements MCPClient {
  private readonly client: Client;
  private readonly transport: StreamableHTTPClientTransport;
  private readonly toolCallTimeoutMs?: number;
  private started = false;
  private closed = false;
  // See StdioMcpClient.ready — distinguishes handshake-phase failures (caller
  // sees them via `connect()` throwing, no unexpectedClose) from post-ready
  // disconnects (the case `onUnexpectedClose` is designed to surface).
  private ready = false;
  private hooksInstalled = false;
  private unexpectedCloseListener: UnexpectedCloseListener | undefined;
  private lastTransportError: Error | undefined;
  // See StdioMcpClient — buffered when the listener has not been installed
  // yet so an early close is replayed instead of dropped.
  private pendingUnexpectedClose: UnexpectedCloseReason | undefined;
  // Latch so `onerror` and a (theoretical) `onclose` for the same transport
  // failure do not double-fire. Once we have decided the connection is dead,
  // additional SDK notifications are noise.
  private unexpectedCloseFired = false;

  constructor(config: McpServerHttpConfig, options: HttpMcpClientOptions = {}) {
    const envLookup = options.envLookup ?? ((name) => process.env[name]);
    const headers = buildMcpHttpHeaders(config, envLookup);

    this.transport = new StreamableHTTPClientTransport(new URL(config.url), {
      requestInit: headers !== undefined ? { headers } : undefined,
      fetch: options.fetch,
      authProvider: options.oauthProvider,
    });
    this.client = new Client({
      name: options.clientName ?? KIMI_MCP_CLIENT_NAME,
      version: options.clientVersion ?? KIMI_MCP_CLIENT_VERSION,
    });
    this.toolCallTimeoutMs = options.toolCallTimeoutMs;
  }

  async connect(): Promise<void> {
    if (this.closed) {
      throw new Error('MCP HTTP client is closed');
    }
    if (this.started) return;
    this.started = true;
    // Install hooks BEFORE the SDK handshake; see StdioMcpClient.connect.
    this.installTransportHooks();
    try {
      await this.client.connect(this.transport);
    } catch (error) {
      await this.closeStartedClient();
      throw error;
    }
    if (this.closed) {
      await this.closeStartedClient();
      throw new Error('MCP HTTP client was closed during startup');
    }
    this.ready = true;
  }