Add server name to log messages, flush messages

pkgs/dart_mcp/example/workflow_client.dart

@@ -162,13 +162,16 @@ final class WorkflowClient extends MCPClient with RootsSupport {
       StreamSinkTransformer.fromHandlers(
         handleData: (String data, EventSink<List<int>> innerSink) {
           innerSink.add(utf8.encode(data));
+          // It's a log, so we want to make sure it's always up-to-date.
+          fileByteSink.flush();
         },
         handleError: (
           Object error,
           StackTrace stackTrace,
           EventSink<List<int>> innerSink,
         ) {
           innerSink.addError(error, stackTrace);
+          fileByteSink.flush();
         },
         handleDone: (EventSink<List<int>> innerSink) {
           innerSink.close();
@@ -377,10 +380,6 @@ final class WorkflowClient extends MCPClient with RootsSupport {
   /// Invokes a function and adds the result as context to the chat history.
   Future<void> _handleFunctionCall(gemini.FunctionCall functionCall) async {
     chatHistory.add(gemini.Content.model([functionCall]));
-    logSink?.add(
-      '+++ Calling function ${functionCall.name} with args: '
-      '${functionCall.args}\n',
-    );
     final connection = connectionForFunction[functionCall.name]!;
     final result = await connection.callTool(
       CallToolRequest(name: functionCall.name, arguments: functionCall.args),

pkgs/dart_mcp/lib/src/api/initialization.dart

@@ -295,7 +295,7 @@ extension type Tools.fromMap(Map<String, Object?> _value) {
   }
 }
 
-/// Describes the name and version of an MCP implementation.
+/// Describes the name and version of an MCP client implementation.
 extension type ClientImplementation.fromMap(Map<String, Object?> _value) {
   factory ClientImplementation({
     required String name,
@@ -306,7 +306,7 @@ extension type ClientImplementation.fromMap(Map<String, Object?> _value) {
   String get version => _value['version'] as String;
 }
 
-/// Describes the name and version of an MCP implementation.
+/// Describes the name and version of an MCP server implementation.
 extension type ServerImplementation.fromMap(Map<String, Object?> _value) {
   factory ServerImplementation({
     required String name,

pkgs/dart_mcp/lib/src/client/client.dart

@@ -128,14 +128,17 @@ base class ServerConnection extends MCPBase {
 
   /// The [ServerImplementation] returned from the [initialize] request.
   ///
-  /// Only assigned after [initialize] has successfully completed.
-  late ServerImplementation serverInfo;
+  /// Only non-null after [initialize] has successfully completed.
+  ServerImplementation? serverInfo;
 
   /// The [ServerCapabilities] returned from the [initialize] request.
   ///
   /// Only assigned after [initialize] has successfully completed.
   late ServerCapabilities serverCapabilities;
 
+  @override
+  String get name => serverInfo?.name ?? super.name;
+
   /// Emits an event any time the server notifies us of a change to the list of
   /// prompts it supports.
   ///
@@ -212,7 +215,7 @@ base class ServerConnection extends MCPBase {
       registerRequestHandler(
         CreateMessageRequest.methodName,
         (CreateMessageRequest request) =>
-            samplingSupport.handleCreateMessage(request, serverInfo),
+            samplingSupport.handleCreateMessage(request, serverInfo!),
       );
     }
 

pkgs/dart_mcp/lib/src/server/server.dart

@@ -48,6 +48,9 @@ abstract base class MCPServer extends MCPBase {
   /// Only assigned after `initialize` has been called.
   late ClientCapabilities clientCapabilities;
 
+  @override
+  String get name => implementation.name;
+
   /// Emits an event any time the client notifies us of a change to the list of
   /// roots it supports.
   ///

pkgs/dart_mcp/lib/src/shared.dart

@@ -2,21 +2,33 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+/// @docImport 'client/client.dart';
+/// @docImport 'server/server.dart';
+library;
+
 import 'dart:async';
 
 import 'package:async/async.dart' show StreamSinkTransformer;
 import 'package:json_rpc_2/json_rpc_2.dart';
 import 'package:meta/meta.dart';
 import 'package:stream_channel/stream_channel.dart';
-
 import 'api/api.dart';
 
-/// Base class for both client and server implementations.
+/// Base class for MCP server-related implementations.
 ///
 /// Handles registering method and notification handlers, sending requests and
 /// notifications, progress support, and any other shared functionality.
+///
+/// See also:
+/// - [MCPServer] A base class to extend when implementing an MCP server.
+/// - [ServerConnection] A class that represents an active server connection.
 base class MCPBase {
-  final Peer _peer;
+  late final Peer _peer;
+
+  /// The name of the associated server.
+  ///
+  /// Used to identify log messages.
+  String get name => 'unknown';
 
   /// Progress controllers by token.
   ///
@@ -27,8 +39,8 @@ base class MCPBase {
   /// Whether the connection with the peer is active.
   bool get isActive => !_peer.isClosed;
 
-  MCPBase(StreamChannel<String> channel, {Sink<String>? protocolLogSink})
-    : _peer = Peer(_maybeForwardMessages(channel, protocolLogSink)) {
+  MCPBase(StreamChannel<String> channel, {Sink<String>? protocolLogSink}) {
+    _peer = Peer(_maybeForwardMessages(channel, protocolLogSink));
     registerNotificationHandler(
       ProgressNotification.methodName,
       _handleProgress,
@@ -150,34 +162,34 @@ base class MCPBase {
         PingRequest.methodName,
         null,
       ).then((_) => true).timeout(timeout, onTimeout: () => false);
-}
 
-/// If [protocolLogSink] is non-null, emits messages to it for all messages
-/// sent over [channel].
-///
-/// This is intended to be written to a file or emitted to a user to aid in
-/// debugging protocol messages between the client and server.
-StreamChannel<String> _maybeForwardMessages(
-  StreamChannel<String> channel,
-  Sink<String>? protocolLogSink,
-) {
-  if (protocolLogSink == null) return channel;
-
-  return channel
-      .transformStream(
-        StreamTransformer.fromHandlers(
-          handleData: (data, sink) {
-            protocolLogSink.add('<<< $data\n');
-            sink.add(data);
-          },
-        ),
-      )
-      .transformSink(
-        StreamSinkTransformer.fromHandlers(
-          handleData: (data, sink) {
-            protocolLogSink.add('>>> $data\n');
-            sink.add(data);
-          },
-        ),
-      );
+  /// If [protocolLogSink] is non-null, emits messages to it for all messages
+  /// sent over [channel].
+  ///
+  /// This is intended to be written to a file or emitted to a user to aid in
+  /// debugging protocol messages between the client and server.
+  StreamChannel<String> _maybeForwardMessages(
+    StreamChannel<String> channel,
+    Sink<String>? protocolLogSink,
+  ) {
+    if (protocolLogSink == null) return channel;
+
+    return channel
+        .transformStream(
+          StreamTransformer.fromHandlers(
+            handleData: (data, sink) {
+              protocolLogSink.add('<<< ($name) $data\n');
+              sink.add(data);
+            },
+          ),
+        )
+        .transformSink(
+          StreamSinkTransformer.fromHandlers(
+            handleData: (data, sink) {
+              protocolLogSink.add('>>> ($name) $data\n');
+              sink.add(data);
+            },
+          ),
+        );
+  }
 }