Use shared Implementation type, add clientInfo field to MCPServer

mcp_examples/bin/file_system_server.dart

@@ -33,10 +33,7 @@ final class SimpleFileSystemServer extends MCPServer
     with LoggingSupport, RootsTrackingSupport, ToolsSupport {
   SimpleFileSystemServer.fromStreamChannel(super.channel)
     : super.fromStreamChannel(
-        implementation: ServerImplementation(
-          name: 'file system',
-          version: '0.0.1',
-        ),
+        implementation: Implementation(name: 'file system', version: '0.0.1'),
       );
 
   @override

mcp_examples/bin/workflow_client.dart

@@ -107,9 +107,7 @@ final class WorkflowClient extends MCPClient with RootsSupport {
        stdinQueue = StreamQueue(
          stdin.transform(utf8.decoder).transform(const LineSplitter()),
        ),
-       super(
-         ClientImplementation(name: 'Gemini workflow client', version: '0.1.0'),
-       ) {
+       super(Implementation(name: 'Gemini workflow client', version: '0.1.0')) {
     logSink = _createLogSink(logFile);
     addRoot(
       Root(

mcp_examples/pubspec.yaml

@@ -14,3 +14,7 @@ dependencies:
   google_generative_ai: ^0.4.7
   path: ^1.9.1
   stream_channel: ^2.1.4
+
+dependency_overrides:
+  dart_mcp:
+    path: ../pkgs/dart_mcp

pkgs/dart_mcp/CHANGELOG.md

@@ -1,5 +1,9 @@
-## 0.2.2-wip
+## 0.2.2
 
+- Refactor `ClientImplementation` and `ServerImplementation` to the shared
+  `Implementation` type to match the spec. The old names are deprecated but will
+  still work until the next breaking release.
+- Add `clientInfo` field to `MCPServer`, assigned during initialization.
 - Move the `done` future from the `ServerConnection` into `MCPBase` so it is
   available to the `MPCServer` class as well.
 

pkgs/dart_mcp/README.md

@@ -36,7 +36,7 @@ an error, which may result in a better UX for the users of the client.
 
 To implement a client, import `package:dart_mcp/client.dart` and extend the
 `MCPClient` class, or directly call its constructor with a
-`ClientImplementation` if you aren't implementing any "capabilities".
+`Implementation` if you aren't implementing any "capabilities".
 
 For each specific MCP capability your client supports, there is a corresponding
 mixin that you can use (`RootsSupport`, `SamplingSupport`, etc). Each mixin has

pkgs/dart_mcp/example/simple_client.dart

@@ -6,7 +6,7 @@ import 'package:dart_mcp/client.dart';
 
 void main() async {
   final client = MCPClient(
-    ClientImplementation(name: 'example dart client', version: '0.1.0'),
+    Implementation(name: 'example dart client', version: '0.1.0'),
   );
   print('connecting to server');
   final server = await client.connectStdioServer('dart', [

pkgs/dart_mcp/example/simple_server.dart

@@ -29,7 +29,7 @@ void main() {
 base class DartMCPServer extends MCPServer with ToolsSupport {
   DartMCPServer(super.channel)
     : super.fromStreamChannel(
-        implementation: ServerImplementation(
+        implementation: Implementation(
           name: 'example dart server',
           version: '0.1.0',
         ),

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

@@ -13,7 +13,7 @@ extension type InitializeRequest._fromMap(Map<String, Object?> _value)
   factory InitializeRequest({
     required ProtocolVersion protocolVersion,
     required ClientCapabilities capabilities,
-    required ClientImplementation clientInfo,
+    required Implementation clientInfo,
     MetaWithProgressToken? meta,
   }) => InitializeRequest._fromMap({
     'protocolVersion': protocolVersion.versionString,
@@ -33,8 +33,7 @@ extension type InitializeRequest._fromMap(Map<String, Object?> _value)
   ClientCapabilities get capabilities =>
       _value['capabilities'] as ClientCapabilities;
 
-  ClientImplementation get clientInfo =>
-      _value['clientInfo'] as ClientImplementation;
+  Implementation get clientInfo => _value['clientInfo'] as Implementation;
 }
 
 /// After receiving an initialize request from the client, the server sends
@@ -44,7 +43,7 @@ extension type InitializeResult.fromMap(Map<String, Object?> _value)
   factory InitializeResult({
     required ProtocolVersion protocolVersion,
     required ServerCapabilities serverCapabilities,
-    required ServerImplementation serverInfo,
+    required Implementation serverInfo,
     String? instructions,
   }) => InitializeResult.fromMap({
     'protocolVersion': protocolVersion.versionString,
@@ -74,8 +73,7 @@ extension type InitializeResult.fromMap(Map<String, Object?> _value)
   ServerCapabilities get capabilities =>
       _value['capabilities'] as ServerCapabilities;
 
-  ServerImplementation get serverInfo =>
-      _value['serverInfo'] as ServerImplementation;
+  Implementation get serverInfo => _value['serverInfo'] as Implementation;
 
   /// Instructions describing how to use the server and its features.
   ///
@@ -295,24 +293,17 @@ extension type Tools.fromMap(Map<String, Object?> _value) {
   }
 }
 
-/// Describes the name and version of an MCP client implementation.
-extension type ClientImplementation.fromMap(Map<String, Object?> _value) {
-  factory ClientImplementation({
-    required String name,
-    required String version,
-  }) => ClientImplementation.fromMap({'name': name, 'version': version});
+/// Describes the name and version of an MCP implementation.
+extension type Implementation.fromMap(Map<String, Object?> _value) {
+  factory Implementation({required String name, required String version}) =>
+      Implementation.fromMap({'name': name, 'version': version});
 
   String get name => _value['name'] as String;
   String get version => _value['version'] as String;
 }
 
-/// Describes the name and version of an MCP server implementation.
-extension type ServerImplementation.fromMap(Map<String, Object?> _value) {
-  factory ServerImplementation({
-    required String name,
-    required String version,
-  }) => ServerImplementation.fromMap({'name': name, 'version': version});
+@Deprecated('Use Implementation instead.')
+typedef ClientImplementation = Implementation;
 
-  String get name => _value['name'] as String;
-  String get version => _value['version'] as String;
-}
+@Deprecated('Use Implementation instead.')
+typedef ServerImplementation = Implementation;

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

@@ -29,7 +29,7 @@ part 'sampling_support.dart';
 /// this will be invoked at the end of base class constructor.
 base class MCPClient {
   /// A description of the client sent to servers during initialization.
-  final ClientImplementation implementation;
+  final Implementation implementation;
 
   MCPClient(this.implementation) {
     initialize();
@@ -128,10 +128,10 @@ base class ServerConnection extends MCPBase {
   /// protocol version.
   late ProtocolVersion protocolVersion;
 
-  /// The [ServerImplementation] returned from the [initialize] request.
+  /// The [Implementation] returned from the [initialize] request.
   ///
   /// Only non-null after [initialize] has successfully completed.
-  ServerImplementation? serverInfo;
+  Implementation? serverInfo;
 
   /// The [ServerCapabilities] returned from the [initialize] request.
   ///

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

@@ -26,6 +26,6 @@ base mixin SamplingSupport on MCPClient {
   /// request gave when it was initialized.
   FutureOr<CreateMessageResult> handleCreateMessage(
     CreateMessageRequest request,
-    ServerImplementation serverInfo,
+    Implementation serverInfo,
   );
 }

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

@@ -32,7 +32,7 @@ abstract base class MCPServer extends MCPBase {
   bool get ready => isActive && _initialized.isCompleted;
 
   /// The name, current version, and other info to give to the client.
-  final ServerImplementation implementation;
+  final Implementation implementation;
 
   /// Instructions for how to use this server, which are given to the client.
   ///
@@ -49,6 +49,11 @@ abstract base class MCPServer extends MCPBase {
   /// Only assigned after `initialize` has been called.
   late ClientCapabilities clientCapabilities;
 
+  /// The client implementation information provided during initialization.
+  ///
+  /// Only assigned after `initialize` has been called.
+  late Implementation clientInfo;
+
   @override
   String get name => implementation.name;
 
@@ -106,6 +111,9 @@ abstract base class MCPServer extends MCPBase {
         _rootsListChangedController!.sink.add,
       );
     }
+
+    clientInfo = request.clientInfo;
+
     assert(!_initialized.isCompleted);
     return InitializeResult(
       protocolVersion: protocolVersion,

pkgs/dart_mcp/pubspec.yaml

@@ -1,5 +1,5 @@
 name: dart_mcp
-version: 0.2.2-wip
+version: 0.2.2
 description: A package for making MCP servers and clients.
 repository: https://github.com/dart-lang/ai/tree/main/pkgs/dart_mcp
 issue_tracker: https://github.com/dart-lang/ai/issues?q=is%3Aissue+is%3Aopen+label%3Apackage%3Adart_mcp

pkgs/dart_mcp/test/api/sampling_test.dart

@@ -45,7 +45,7 @@ final class SamplingTestMCPClient extends TestMCPClient with SamplingSupport {
   @override
   FutureOr<CreateMessageResult> handleCreateMessage(
     CreateMessageRequest request,
-    ServerImplementation serverInfo,
+    Implementation serverInfo,
   ) {
     if (nextResult case final result?) {
       nextResult = null;

pkgs/dart_mcp/test/client_and_server_test.dart

@@ -23,6 +23,12 @@ void main() {
     expect(initializeResult.instructions, environment.server.instructions);
     expect(initializeResult.protocolVersion, ProtocolVersion.latestSupported);
 
+    expect(environment.server.clientInfo, environment.client.implementation);
+    expect(
+      environment.serverConnection.serverInfo,
+      environment.server.implementation,
+    );
+
     expect(
       environment.serverConnection.listTools(ListToolsRequest()),
       throwsA(
@@ -337,7 +343,7 @@ void main() {
           InitializeRequest(
             protocolVersion: ProtocolVersion.latestSupported,
             capabilities: ClientCapabilities(),
-            clientInfo: ClientImplementation(name: '', version: ''),
+            clientInfo: Implementation(name: '', version: ''),
           ),
         ),
         throwsA(

pkgs/dart_mcp/test/test_utils.dart

@@ -78,16 +78,13 @@ class TestEnvironment<Client extends MCPClient, Server extends MCPServer> {
 
 base class TestMCPClient extends MCPClient {
   TestMCPClient()
-    : super(ClientImplementation(name: 'test client', version: '0.1.0'));
+    : super(Implementation(name: 'test client', version: '0.1.0'));
 }
 
 base class TestMCPServer extends MCPServer {
   TestMCPServer(super.channel, {super.protocolLogSink})
     : super.fromStreamChannel(
-        implementation: ServerImplementation(
-          name: 'test server',
-          version: '0.1.0',
-        ),
+        implementation: Implementation(name: 'test server', version: '0.1.0'),
         instructions: 'A test server',
       );
 }

pkgs/dart_mcp_server/lib/src/server.dart

@@ -40,7 +40,7 @@ final class DartMCPServer extends MCPServer
     this.forceRootsFallback = false,
     super.protocolLogSink,
   }) : super.fromStreamChannel(
-         implementation: ServerImplementation(
+         implementation: Implementation(
            name: 'dart and flutter tooling',
            version: '0.1.0-wip',
          ),

pkgs/dart_mcp_server/pubspec.yaml

@@ -15,7 +15,7 @@ dependencies:
   args: ^2.7.0
   async: ^2.13.0
   collection: ^1.19.1
-  dart_mcp: ^0.2.1
+  dart_mcp: ^0.2.2
   dds_service_extensions: ^2.0.1
   devtools_shared: ^11.2.0
   dtd: ^2.4.0

pkgs/dart_mcp_server/test/test_harness.dart

@@ -282,7 +282,7 @@ final class AppDebugSession {
 final class DartToolingMCPClient extends MCPClient with RootsSupport {
   DartToolingMCPClient()
     : super(
-        ClientImplementation(
+        Implementation(
           name: 'test client for the dart tooling mcp server',
           version: '0.1.0',
         ),

pkgs/dart_mcp_server/test/tools/roots_fallback_support_test.dart

@@ -190,7 +190,7 @@ void main() {
 final class TestClientWithoutRoots extends MCPClient {
   TestClientWithoutRoots()
     : super(
-        ClientImplementation(
+        Implementation(
           name: 'test client with no roots support',
           version: '0.1.0',
         ),
@@ -201,7 +201,7 @@ final class TestClientWithoutRoots extends MCPClient {
 final class TestClientWithRoots extends MCPClient with RootsSupport {
   TestClientWithRoots()
     : super(
-        ClientImplementation(
+        Implementation(
           name: 'test client with roots support',
           version: '0.1.0',
         ),
@@ -223,10 +223,7 @@ final class TestServer extends MCPServer
     super.protocolLogSink,
     this.forceRootsFallback = false,
   }) : super.fromStreamChannel(
-         implementation: ServerImplementation(
-           name: 'test server',
-           version: '0.1.0',
-         ),
+         implementation: Implementation(name: 'test server', version: '0.1.0'),
          instructions: 'A test server with roots fallback support',
        );
 }