Register samplingRequest with a unique service name

pkgs/dart_mcp_server/lib/src/mixins/dtd.dart

@@ -19,6 +19,7 @@ import '../arg_parser.dart';
 import '../utils/analytics.dart';
 import '../utils/constants.dart';
 import '../utils/tools_configuration.dart';
+import '../utils/uuid.dart';
 
 /// Constants used by the MCP server to register services on DTD.
 ///
@@ -78,6 +79,34 @@ base mixin DartToolingDaemonSupport
   /// Whether or not to enable the screenshot tool.
   bool get enableScreenshots;
 
+  /// A unique identifier for this server instance.
+  ///
+  /// This is generated on first access and then cached. It is used to create
+  /// a unique service name when registering services on DTD.
+  ///
+  /// Can only be accessed after `initialize` has been called.
+  String get clientId {
+    if (_clientId != null) return _clientId!;
+    final clientName = clientInfo.title ?? clientInfo.name;
+    _clientId = generateClientId(clientName);
+    return _clientId!;
+  }
+
+  String? _clientId;
+
+  @visibleForTesting
+  String generateClientId(String clientName) {
+    // Sanitizes the client name by:
+    // 1. replacing whitespace, '-', and '.' with '_'
+    // 2. removing all non-alphanumeric characters except '_'
+    final sanitizedClientName = clientName
+        .trim()
+        .toLowerCase()
+        .replaceAll(RegExp(r'[\s\.\-]+'), '_')
+        .replaceAll(RegExp(r'[^a-zA-Z0-9_]'), '');
+    return '${sanitizedClientName}_${generateShortUUID()}';
+  }
+
   /// Called when the DTD connection is lost, resets all associated state.
   Future<void> _resetDtd() async {
     _dtd = null;
@@ -290,17 +319,11 @@ base mixin DartToolingDaemonSupport
     final dtd = _dtd!;
 
     if (clientCapabilities.sampling != null) {
-      try {
-        await dtd.registerService(
-          McpServiceConstants.serviceName,
-          McpServiceConstants.samplingRequest,
-          _handleSamplingRequest,
-        );
-      } on RpcException catch (e) {
-        // It is expected for there to be an exception if the sampling service
-        // was already registered by another Dart MCP Server.
-        if (e.code != RpcErrorCodes.kServiceAlreadyRegistered) rethrow;
-      }
+      await dtd.registerService(
+        '${McpServiceConstants.serviceName}_$clientId',
+        McpServiceConstants.samplingRequest,
+        _handleSamplingRequest,
+      );
     }
   }
 

pkgs/dart_mcp_server/lib/src/utils/uuid.dart

@@ -0,0 +1,23 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// 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.
+
+import 'dart:math' show Random;
+
+/// Generates a short, 8-character hex string from 32 bits of random data.
+///
+/// This is not a standard UUID but is sufficient for use cases where a short,
+/// unique-enough identifier is needed.
+String generateShortUUID() => _bitsDigits(16, 4) + _bitsDigits(16, 4);
+
+// Note: The following private helpers were copied over from:
+// https://github.com/dart-lang/webdev/blob/e2d14f1050fa07e9a60455cf9d2b8e6f4e9c332c/frontend_server_common/lib/src/uuid.dart
+final Random _random = Random();
+
+String _bitsDigits(int bitCount, int digitCount) =>
+    _printDigits(_generateBits(bitCount), digitCount);
+
+int _generateBits(int bitCount) => _random.nextInt(1 << bitCount);
+
+String _printDigits(int value, int count) =>
+    value.toRadixString(16).padLeft(count, '0');

pkgs/dart_mcp_server/test/tools/dtd_test.dart

@@ -107,10 +107,41 @@ void main() {
           return (responseContent['text'] as String).split('\n');
         }
 
+        Future<String> getSamplingServiceName(
+          DartToolingDaemon dtdClient,
+        ) async {
+          final services = await dtdClient.getRegisteredServices();
+          final samplingService = services.clientServices.firstWhere(
+            (s) => s.name.startsWith(McpServiceConstants.serviceName),
+          );
+          return samplingService.name;
+        }
+
+        test('is registered with correct name format', () async {
+          final dtdClient = testHarness.fakeEditorExtension.dtd;
+          final services = await dtdClient.getRegisteredServices();
+          final samplingService = services.clientServices.first;
+          final sanitizedClientName =
+              'test_client_for_the_dart_tooling_mcp_server';
+          expect(
+            samplingService.name,
+            startsWith(
+              '${McpServiceConstants.serviceName}_${sanitizedClientName}_',
+            ),
+          );
+          // Check that the service name ends with an 8-character ID.
+          expect(samplingService.name, matches(RegExp(r'[a-f0-9]{8}$')));
+          expect(
+            samplingService.methods,
+            contains(McpServiceConstants.samplingRequest),
+          );
+        });
+
         test('can make a sampling request with text', () async {
           final dtdClient = testHarness.fakeEditorExtension.dtd;
+          final samplingServiceName = await getSamplingServiceName(dtdClient);
           final response = await dtdClient.call(
-            McpServiceConstants.serviceName,
+            samplingServiceName,
             McpServiceConstants.samplingRequest,
             params: {
               'messages': [
@@ -130,8 +161,9 @@ void main() {
 
         test('can make a sampling request with an image', () async {
           final dtdClient = testHarness.fakeEditorExtension.dtd;
+          final samplingServiceName = await getSamplingServiceName(dtdClient);
           final response = await dtdClient.call(
-            McpServiceConstants.serviceName,
+            samplingServiceName,
             McpServiceConstants.samplingRequest,
             params: {
               'messages': [
@@ -155,8 +187,9 @@ void main() {
 
         test('can make a sampling request with audio', () async {
           final dtdClient = testHarness.fakeEditorExtension.dtd;
+          final samplingServiceName = await getSamplingServiceName(dtdClient);
           final response = await dtdClient.call(
-            McpServiceConstants.serviceName,
+            samplingServiceName,
             McpServiceConstants.samplingRequest,
             params: {
               'messages': [
@@ -177,8 +210,9 @@ void main() {
 
         test('can make a sampling request with an embedded resource', () async {
           final dtdClient = testHarness.fakeEditorExtension.dtd;
+          final samplingServiceName = await getSamplingServiceName(dtdClient);
           final response = await dtdClient.call(
-            McpServiceConstants.serviceName,
+            samplingServiceName,
             McpServiceConstants.samplingRequest,
             params: {
               'messages': [
@@ -201,8 +235,9 @@ void main() {
 
         test('can make a sampling request with mixed content', () async {
           final dtdClient = testHarness.fakeEditorExtension.dtd;
+          final samplingServiceName = await getSamplingServiceName(dtdClient);
           final response = await dtdClient.call(
-            McpServiceConstants.serviceName,
+            samplingServiceName,
             McpServiceConstants.samplingRequest,
             params: {
               'messages': [
@@ -231,8 +266,9 @@ void main() {
 
         test('can handle user and assistant messages', () async {
           final dtdClient = testHarness.fakeEditorExtension.dtd;
+          final samplingServiceName = await getSamplingServiceName(dtdClient);
           final response = await dtdClient.call(
-            McpServiceConstants.serviceName,
+            samplingServiceName,
             McpServiceConstants.samplingRequest,
             params: {
               'messages': [
@@ -262,8 +298,9 @@ void main() {
 
         test('forwards all messages, even those with unknown types', () async {
           final dtdClient = testHarness.fakeEditorExtension.dtd;
+          final samplingServiceName = await getSamplingServiceName(dtdClient);
           final response = await dtdClient.call(
-            McpServiceConstants.serviceName,
+            samplingServiceName,
             McpServiceConstants.samplingRequest,
             params: {
               'messages': [
@@ -285,9 +322,10 @@ void main() {
 
         test('throws for invalid requests', () async {
           final dtdClient = testHarness.fakeEditorExtension.dtd;
+          final samplingServiceName = await getSamplingServiceName(dtdClient);
           try {
             await dtdClient.call(
-              McpServiceConstants.serviceName,
+              samplingServiceName,
               McpServiceConstants.samplingRequest,
               params: {
                 'messages': [
@@ -378,6 +416,65 @@ void main() {
         await testHarness.connectToDtd();
       });
 
+      group('generateClientId creates ID from client name', () {
+        test('removes whitespaces', () {
+          // Single whitespace character.
+          expect(
+            server.generateClientId('Example Name'),
+            startsWith('example_name_'),
+          );
+          // Multiple whitespace characters.
+          expect(
+            server.generateClientId('Example   Name'),
+            startsWith('example_name_'),
+          );
+          // Newline and other whitespace.
+          expect(
+            server.generateClientId('Example\n\tName'),
+            startsWith('example_name_'),
+          );
+          // Whitespace at the end.
+          expect(
+            server.generateClientId('Example Name\n'),
+            startsWith('example_name_'),
+          );
+        });
+
+        test('replaces periods and dashes with underscores', () {
+          // Replaces periods.
+          expect(
+            server.generateClientId('Example.Client.Name'),
+            startsWith('example_client_name_'),
+          );
+          // Replaces dashes.
+          expect(
+            server.generateClientId('example-client-name'),
+            startsWith('example_client_name_'),
+          );
+        });
+
+        test('removes special characters', () {
+          expect(
+            server.generateClientId('Example!@#Client\$%^Name'),
+            startsWith('exampleclientname_'),
+          );
+        });
+
+        test('handles a mix of sanitization rules', () {
+          expect(
+            server.generateClientId('  Example Client.Name!@# '),
+            startsWith('example_client_name_'),
+          );
+        });
+
+        test('ends with an 8-character uuid', () {
+          expect(
+            server.generateClientId('Example name'),
+            matches(RegExp(r'[a-f0-9]{8}$')),
+          );
+        });
+      });
+
       group('$VmService management', () {
         late Directory appDir;
         final appPath = 'bin/main.dart';