Update mcp-server command to be an alias for 'run dart_mcp_server@'

Strips the dart-lang/ai dependency from the SDK entirely, as well as the snapshot.

Bug: https://github.com/dart-lang/ai/issues/479
Change-Id: Id919c6a8fbf5fedeffb37e5181bc2fbd85adf986
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/507220
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Ben Konyi <bkonyi@google.com>
Auto-Submit: Jake Macdonald <jakemac@google.com>

DEPS

@@ -134,7 +134,6 @@ vars = {
   ### /third_party/pkg dependencies
   # 'tools/rev_sdk_deps.dart' will rev pkg dependencies to their latest; put an
   # EOL comment after a dependency to instead pin at the current revision.
-  "ai_rev": "9c96bfe5f091c9451eff5b59c9bffeb2e806b875",
   "core_rev": "be0b1531c445a185d3e93887b8d0355fc766c314",
   "dartdoc_rev": "77a52b6125ce8cc8a88a8a399d80701254e43838",
   "ecosystem_rev": "319ff812d463fc194999a0d4b682097450279332",
@@ -338,8 +337,6 @@ deps = {
       Var('chromium_git') + '/external/github.com/mdn/browser-compat-data' +
       "@" + Var("browser-compat-data_tag"),
 
-  Var("dart_root") + "/third_party/pkg/ai":
-      Var("dart_git") + "ai.git" + "@" + Var("ai_rev"),
   Var("dart_root") + "/third_party/pkg/core":
       Var("dart_git") + "core.git" + "@" + Var("core_rev"),
   Var("dart_root") + "/third_party/pkg/dart_style":

pkg/dart2native/lib/sdk.dart

@@ -90,10 +90,6 @@ class Sdk {
         'dart2wasm_product.snapshot',
       );
 
-  String get dartMCPServerAotSnapshot => _snapshotPathFor(
-        'dart_mcp_server_aot.dart.snapshot',
-      );
-
   String get ddsAotSnapshot => _snapshotPathFor(
         'dds_aot.dart.snapshot',
       );

pkg/dartdev/lib/dartdev.dart

@@ -11,6 +11,7 @@ import 'package:args/args.dart';
 import 'package:args/command_runner.dart';
 import 'package:cli_util/cli_logging.dart';
 import 'package:dart_style/src/cli/format_command.dart';
+import 'package:dartdev/src/commands/dart_mcp_server.dart';
 import 'package:meta/meta.dart';
 import 'package:pub/pub.dart';
 import 'package:unified_analytics/unified_analytics.dart';
@@ -20,7 +21,6 @@ import 'src/commands/build.dart';
 import 'src/commands/compilation_server.dart';
 import 'src/commands/compile.dart';
 import 'src/commands/create.dart';
-import 'src/commands/dart_mcp_server.dart';
 import 'src/commands/debug_adapter.dart';
 import 'src/commands/development_service.dart';
 import 'src/commands/devtools.dart';

pkg/dartdev/lib/src/commands/dart_mcp_server.dart

@@ -4,14 +4,11 @@
 
 import 'dart:async';
 
-import 'package:args/args.dart';
-import 'package:dart_mcp_server/arg_parser.dart' as dart_mcp_server;
-import 'package:dartdev/src/utils.dart';
+import 'package:dartdev/src/commands/run.dart';
 
 import '../core.dart';
-import '../sdk.dart';
-import '../vm_interop_handler.dart';
 
+/// This command is now just an alias for `dart run dart_mcp_server@`.
 class DartMCPServerCommand extends DartdevCommand {
   static const String cmdName = 'mcp-server';
 
@@ -20,12 +17,6 @@ A stdio based Model Context Protocol (MCP) server to aid in Dart and Flutter dev
 
   static const _experimentFlag = 'experimental-mcp-server';
 
-  @override
-  ArgParser createArgParser() => dart_mcp_server.createArgParser(
-    usageLineLength: dartdevUsageLineLength,
-    includeHelp: false,
-  );
-
   DartMCPServerCommand({bool verbose = false})
     : super(cmdName, cmdDescription, verbose, hidden: true) {
     argParser.addFlag(
@@ -46,26 +37,33 @@ A stdio based Model Context Protocol (MCP) server to aid in Dart and Flutter dev
 
   @override
   Future<int> run() async {
-    final parsedArgs = argResults!;
+    // We want the global arguments as we will be delegating back to the
+    // command runner to run the new command.
+    final forwardedArgs = globalResults!.arguments.toList();
 
     // Strip out the experiment flag before forwarding on the args, this flag
-    // isn't supported by the actual binary.
-    final forwardedArgs = argResults!.arguments.toList();
-    if (parsedArgs.wasParsed(_experimentFlag)) {
+    // isn't supported by the actual package.
+    //
+    // Have to check the local arg results here, as this flag only exists on the
+    // command arg parser and not the global one.
+    if (argResults!.wasParsed(_experimentFlag)) {
       forwardedArgs.removeWhere((arg) => arg.endsWith(_experimentFlag));
     }
-    try {
-      VmInteropHandler.run(sdk.dartMCPServerAotSnapshot, [
-        ...forwardedArgs,
-      ], useExecProcess: false);
-      return 0;
-    } catch (e, st) {
-      log.stderr('Error: launching Dart MCP server failed');
-      log.stderr(e.toString());
-      if (verbose) {
-        log.stderr(st.toString());
-      }
-      return 255;
+
+    // Find the index of the original command argument and replace it with
+    // `run dart_mcp_server@`.
+    final commandIndex = forwardedArgs.indexOf(cmdName);
+    if (commandIndex == -1) {
+      throw StateError(
+        'Reached mcp-server command without `mcp-server` in arguments.',
+      );
     }
+    forwardedArgs.replaceRange(commandIndex, commandIndex + 1, [
+      RunCommand.cmdName,
+      'dart_mcp_server@',
+    ]);
+
+    // Finally, run the new command.
+    return await runner!.run(forwardedArgs) ?? 0;
   }
 }

pkg/dartdev/pubspec.yaml

@@ -19,7 +19,6 @@ dependencies:
   collection: any
   dart2native: any
   dart_data_home: any
-  dart_mcp_server: any
   dart_style: any
   dartdoc: any
   data_assets: any
@@ -47,7 +46,6 @@ dependencies:
 
 # Use 'any' constraints here; we get our versions from the DEPS file.
 dev_dependencies:
-  dart_mcp: any
   expect: any
   lints: any
   pub_semver: any

pkg/dartdev/test/commands/mcp_server_test.dart

@@ -2,52 +2,70 @@
 // 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:io';
-
-import 'package:dart_mcp/client.dart';
-import 'package:dart_mcp/stdio.dart';
+import 'dart:async';
+import 'package:args/command_runner.dart';
+import 'package:dartdev/src/commands/dart_mcp_server.dart';
 import 'package:test/test.dart';
 
 void main() {
-  group('dart mcp-server', () {
-    for (var withExperiment in const [true, false]) {
-      test(
-        'can be connected with a client with${withExperiment ? '' : 'out'} the experiment flag',
-        () async {
-          final client = TestMCPClient();
-          addTearDown(client.shutdown);
-          final process = await Process.start(Platform.resolvedExecutable, [
-            'mcp-server',
-            if (withExperiment) '--experimental-mcp-server',
-          ]);
+  group('DartMCPServerCommand', () {
+    late FakeRunner runner;
+    late DartMCPServerCommand command;
 
-          final connection = client.connectServer(
-            stdioChannel(input: process.stdout, output: process.stdin),
-          );
-          connection.done.then((_) => process.kill());
+    setUp(() {
+      runner = FakeRunner();
+      command = DartMCPServerCommand();
+      runner.addCommand(command);
+    });
 
-          final initializeResult = await connection.initialize(
-            InitializeRequest(
-              protocolVersion: ProtocolVersion.latestSupported,
-              capabilities: client.capabilities,
-              clientInfo: client.implementation,
-            ),
-          );
+    test('delegates to `run dart_mcp_server@`', () async {
+      await runner.run(['mcp-server']);
+      expect(runner.capturedArgs, equals(['run', 'dart_mcp_server@']));
+    });
 
-          expect(
-            initializeResult.protocolVersion,
-            ProtocolVersion.latestSupported,
-          );
-          connection.notifyInitialized();
-
-          expect(await connection.listTools(ListToolsRequest()), isNotEmpty);
-        },
+    test('forwards command arguments', () async {
+      await runner.run(['mcp-server', 'foo', 'bar']);
+      expect(
+        runner.capturedArgs,
+        equals(['run', 'dart_mcp_server@', 'foo', 'bar']),
       );
-    }
+    });
+
+    test('strips experimental flag', () async {
+      await runner.run(['mcp-server', '--experimental-mcp-server']);
+      expect(runner.capturedArgs, equals(['run', 'dart_mcp_server@']));
+    });
+
+    test('strips experimental flag and keeps other args', () async {
+      await runner.run(['mcp-server', '--experimental-mcp-server', 'foo']);
+      expect(runner.capturedArgs, equals(['run', 'dart_mcp_server@', 'foo']));
+    });
+
+    test('forwards global arguments', () async {
+      runner.argParser.addFlag('global-flag', negatable: false);
+      await runner.run(['--global-flag', 'mcp-server']);
+      expect(
+        runner.capturedArgs,
+        equals(['--global-flag', 'run', 'dart_mcp_server@']),
+      );
+    });
   });
 }
 
-base class TestMCPClient extends MCPClient {
-  TestMCPClient()
-    : super(Implementation(name: 'test client', version: '0.1.0'));
+class FakeRunner extends CommandRunner<int> {
+  List<String>? capturedArgs;
+  bool isFirstCall = true;
+
+  FakeRunner() : super('dart', 'dart command runner');
+
+  @override
+  Future<int?> run(Iterable<String> args) async {
+    if (isFirstCall) {
+      isFirstCall = false;
+      return await super.run(args);
+    } else {
+      capturedArgs = args.toList();
+      return 0;
+    }
+  }
 }

pubspec.yaml

@@ -140,10 +140,6 @@ dependency_overrides:
     path: third_party/pkg/tools/pkgs/csslib
   dart_flutter_team_lints:
     path: third_party/pkg/ecosystem/pkgs/dart_flutter_team_lints
-  dart_mcp:
-    path: third_party/pkg/ai/pkgs/dart_mcp
-  dart_mcp_server:
-    path: third_party/pkg/ai/pkgs/dart_mcp_server
   dart_style:
     path: third_party/pkg/dart_style
   dartdoc:

sdk/BUILD.gn

@@ -150,11 +150,6 @@ if (dart_target_arch != "ia32" && dart_target_arch != "x86") {
       "../utils/dtd:dtd_aot",
       "dart_tooling_daemon_aot",
     ],
-    [
-      "dart_mcp_server_aot_product",
-      "../utils/dart_mcp_server:dart_mcp_server_aot",
-      "dart_mcp_server_aot",
-    ],
   ]
   if (include_experimental_vm_service) {
     _platform_sdk_snapshots += [ [

utils/dart_mcp_server/BUILD.gn

@@ -1,31 +0,0 @@
-# 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("../../runtime/runtime_args.gni")
-import("../aot_snapshot.gni")
-
-group("dart_mcp_server_aot") {
-  public_deps = [
-    ":dart_mcp_server_aot_product_snapshot",
-    ":dart_mcp_server_aot_snapshot",
-  ]
-}
-
-aot_snapshot("dart_mcp_server_aot_snapshot") {
-  main_dart = "dart_mcp_server.dart"
-  output = "$root_gen_dir/dart_mcp_server_aot.dart.snapshot"
-}
-
-aot_snapshot("dart_mcp_server_aot_product_snapshot") {
-  main_dart = "dart_mcp_server.dart"
-  output = "$root_gen_dir/dart_mcp_server_aot_product.dart.snapshot"
-
-  # dartaotruntime has dart_product_config applied to it,
-  # so it is built in product mode in both release and
-  # product builds, and is only built in debug mode in debug
-  # builds. The following line ensures that the dartaotruntime
-  # and dart_mcp_server_aot snapshot in an SDK build are
-  # always compatible with each other.
-  force_product_mode = !dart_debug
-}

utils/dart_mcp_server/dart_mcp_server.dart

@@ -1,36 +0,0 @@
-// 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.
-
-/// A custom entrypoint used by `dart mcp-server`. Injects an analytics instance
-/// using the [DashTool.dartTool] tool.
-library;
-
-import 'dart:io';
-
-import 'package:dart_mcp_server/dart_mcp_server.dart';
-import 'package:unified_analytics/unified_analytics.dart';
-
-void main(List<String> args) async {
-  DashTool? tool;
-  if (Platform.environment['DASH__TOOL'] case final toolEnv?) {
-    try {
-      tool = DashTool.fromLabel(toolEnv);
-    } catch (e) {
-      // Ignore errors, but don't track analytics for unrecognized tools.
-    }
-  } else {
-    // We default to the `dart` tool if none specified.
-    tool = DashTool.dartTool;
-  }
-
-  final analytics = tool != null
-      ? Analytics(
-          tool: tool,
-          // The actual version is the part up to the first space.
-          dartVersion: Platform.version.split(' ').first,
-        )
-      : null;
-
-  exitCode = await DartMCPServer.run(args, analytics: analytics);
-}