Function connectClient

packages/plugins/mcp/src/sdk/connection.ts:395–437

(input: {
  transport: string;
  createTransport: (sdk: McpClientSdk) => Parameters<Client["connect"]>[0];
  versionNegotiation?: { readonly mode: "auto" };
})

  });

const connectClient = (input: {
  transport: string;
  createTransport: (sdk: McpClientSdk) => Parameters<Client["connect"]>[0];
  versionNegotiation?: { readonly mode: "auto" };
}): Effect.Effect<McpConnection, McpConnectionError | McpOAuthReauthorizationRequired> =>
  Effect.gen(function* () {
    const sdk = yield* Effect.tryPromise({
      try: () => loadMcpClientSdk(),
      catch: () =>
        new McpConnectionError({
          transport: input.transport,
          message: "Failed to load MCP client module",
        }),
    });
    const client = createClient(sdk, input.versionNegotiation);
    const transportInstance = input.createTransport(sdk);

    yield* Effect.tryPromise({
      // Interruption (an HTTP 499 cancelling a health check, the discovery
      // timeout) aborts this signal; the SDK then fails the in-flight
      // handshake and closes the transport. Without it the abandoned connect
      // kept the spawned stdio child alive forever; `docker run -i --rm`
      // integrations stranded a container per interrupted dial (#1631).
      try: (signal) => client.connect(transportInstance, { signal }),
      catch: (cause) =>
        connectionFailure(input.transport, `Failed connecting via ${input.transport}`, cause),
    }).pipe(
      // The negotiated era ("modern" = 2026-07-28 server/discover, "legacy" =
      // 2025 initialize) is otherwise invisible: both eras list and call tools
      // identically, so traces are the one place an integration author can
      // verify which handshake a connection actually used.
      Effect.tap(() =>
        Effect.annotateCurrentSpan({
          "plugin.mcp.protocol_era": client.getProtocolEra() ?? "unknown",
        }),
      ),
      Effect.withSpan("plugin.mcp.connection.handshake", {
        attributes: { "plugin.mcp.transport": input.transport },
      }),
    );

    return connectionFromClient(client);
  });

// ---------------------------------------------------------------------------
// Public factory