Add Claude Code plugin marketplace

.claude-plugin/marketplace.json

@@ -0,0 +1,15 @@
+{
+  "name": "flutter",
+  "owner": {
+    "name": "The Flutter Authors"
+  },
+  "description": "Agent skills for Flutter app development, authored by the Flutter and Dart teams.",
+  "plugins": [
+    {
+      "name": "flutter-skills",
+      "source": "./plugins/flutter-skills",
+      "description": "Task-based skills that teach coding agents happy-path Flutter workflows: widget and integration tests, widget previews, responsive layouts, declarative routing, localization, HTTP networking, JSON serialization, and layered architecture best practices.",
+      "category": "development"
+    }
+  ]
+}

.github/workflows/marketplace_workflow.yaml

@@ -0,0 +1,75 @@
+name: marketplace
+permissions: read-all
+
+on:
+  pull_request:
+    paths:
+      - '.github/workflows/marketplace_workflow.yaml'
+      - 'tool/marketplace_check/**'
+      - '.claude-plugin/**'
+      - 'plugins/**'
+  push:
+    branches: [ main ]
+    paths:
+      - '.github/workflows/marketplace_workflow.yaml'
+      - 'tool/marketplace_check/**'
+      - '.claude-plugin/**'
+      - 'plugins/**'
+  schedule:
+    - cron: '0 0 * * 0' # weekly
+
+defaults:
+  run:
+    working-directory: tool/marketplace_check
+
+jobs:
+  analyze_and_test:
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v6
+      - uses: dart-lang/setup-dart@v1
+        with:
+          sdk: stable
+
+      - run: dart pub get
+
+      - run: dart analyze --fatal-infos
+
+      - run: dart test
+
+  formatting:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: dart-lang/setup-dart@v1
+        with:
+          sdk: stable
+
+      - run: dart pub get
+
+      - run: dart format --output=none --set-exit-if-changed .
+
+  validate:
+    runs-on: ubuntu-latest
+    # Override the workflow-level working directory so the validator runs
+    # against the repository root, not tool/marketplace_check.
+    defaults:
+      run:
+        working-directory: .
+    steps:
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+
+      - run: npm install -g @anthropic-ai/claude-code
+
+      # The canonical schema validator (unknown fields, duplicate names, path
+      # traversal, version mismatches). Runs offline; no API key needed.
+      - run: claude plugin validate .
+
+      - run: claude plugin validate ./plugins/flutter-skills

README.md

@@ -17,6 +17,16 @@ folder that most agents use.
 npx skills add flutter/skills --skill '*' --agent universal
 ```
 
+### Install with Claude Code
+
+If you use [Claude Code](https://www.claude.com/product/claude-code), install the
+skills as a plugin from the marketplace bundled in this repo:
+
+```bash
+/plugin marketplace add flutter/skills
+/plugin install flutter-skills@flutter
+```
+
 ## Updating Skills
 
 To update, run the following command:

plugins/flutter-skills/.claude-plugin/plugin.json

@@ -0,0 +1,11 @@
+{
+  "name": "flutter-skills",
+  "description": "Task-based skills that teach coding agents happy-path Flutter workflows: widget and integration tests, widget previews, responsive layouts, declarative routing, localization, HTTP networking, JSON serialization, and layered architecture best practices.",
+  "author": {
+    "name": "The Flutter Authors"
+  },
+  "homepage": "https://github.com/flutter/skills",
+  "repository": "https://github.com/flutter/skills",
+  "license": "BSD-3-Clause",
+  "keywords": ["flutter", "dart", "mobile", "testing", "ui", "skills"]
+}

plugins/flutter-skills/skills

@@ -0,0 +1 @@
+../../skills

tool/marketplace_check/analysis_options.yaml

@@ -0,0 +1,7 @@
+include: package:lints/recommended.yaml
+
+analyzer:
+  language:
+    strict-casts: true
+    strict-inference: true
+    strict-raw-types: true

tool/marketplace_check/pubspec.yaml

@@ -0,0 +1,13 @@
+name: marketplace_check
+description: >-
+  Tests that verify the Claude plugin marketplace wiring (marketplace.json,
+  the flutter-skills plugin manifest, and the skills symlink) stays correct.
+publish_to: 'none'
+
+environment:
+  sdk: ^3.10.8
+
+dev_dependencies:
+  lints: ^6.0.0
+  path: ^1.9.1
+  test: ^1.25.6

tool/marketplace_check/test/marketplace_plugin_test.dart

@@ -0,0 +1,144 @@
+// Copyright (c) 2026, 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:convert';
+import 'dart:io';
+
+import 'package:path/path.dart' as p;
+import 'package:test/test.dart';
+
+/// Walks up from [start] until it finds the directory that contains
+/// `.claude-plugin/marketplace.json`, which marks the repository root.
+///
+/// This lets the test run both from the repository root and from the
+/// `tool/marketplace_check` working directory used by CI.
+Directory _findRepoRoot(Directory start) {
+  var dir = start;
+  while (true) {
+    final marker = File(p.join(dir.path, '.claude-plugin', 'marketplace.json'));
+    if (marker.existsSync()) {
+      return dir;
+    }
+    final parent = dir.parent;
+    if (p.equals(parent.path, dir.path)) {
+      throw StateError(
+        'Could not find .claude-plugin/marketplace.json walking up from '
+        '${start.path}',
+      );
+    }
+    dir = parent;
+  }
+}
+
+Map<String, dynamic> _readJson(File file) {
+  expect(file.existsSync(), isTrue, reason: '${file.path} should exist');
+  return jsonDecode(file.readAsStringSync()) as Map<String, dynamic>;
+}
+
+void main() {
+  final repoRoot = _findRepoRoot(Directory.current);
+  final marketplaceFile = File(
+    p.join(repoRoot.path, '.claude-plugin', 'marketplace.json'),
+  );
+  final pluginLink = p.join(
+    repoRoot.path,
+    'plugins',
+    'flutter-skills',
+    'skills',
+  );
+
+  group('Claude plugin marketplace', () {
+    test('marketplace.json declares the flutter-skills plugin', () {
+      final marketplace = _readJson(marketplaceFile);
+
+      expect(marketplace['name'], 'flutter');
+      expect(marketplace['owner'], isA<Map<String, dynamic>>());
+
+      final plugins = marketplace['plugins'] as List<dynamic>;
+      expect(plugins, hasLength(1));
+
+      final plugin = plugins.single as Map<String, dynamic>;
+      expect(plugin['name'], 'flutter-skills');
+
+      // Guards against regressing to `source: "./"`, which would copy the
+      // entire repo (tool/, resources/, .agents/) into every user's cache.
+      expect(plugin['source'], './plugins/flutter-skills');
+    });
+
+    test('plugin source resolves to a directory with a plugin manifest', () {
+      final marketplace = _readJson(marketplaceFile);
+      final plugin =
+          (marketplace['plugins'] as List<dynamic>).single
+              as Map<String, dynamic>;
+      final source = plugin['source'] as String;
+
+      expect(source, startsWith('./'));
+      expect(source, isNot(contains('..')));
+
+      final pluginDir = Directory(p.join(repoRoot.path, source));
+      expect(
+        pluginDir.existsSync(),
+        isTrue,
+        reason: 'plugin source "$source" should exist',
+      );
+
+      final manifest = _readJson(
+        File(p.join(pluginDir.path, '.claude-plugin', 'plugin.json')),
+      );
+      expect(manifest['name'], plugin['name']);
+    });
+
+    test('skills symlink resolves to the top-level skills/ directory', () {
+      expect(
+        FileSystemEntity.isLinkSync(pluginLink),
+        isTrue,
+        reason:
+            '"$pluginLink" must be a symlink. On Windows, ensure git checks '
+            'out symlinks (core.symlinks=true / Developer Mode).',
+      );
+
+      final resolvedLink = Link(pluginLink).resolveSymbolicLinksSync();
+      final canonicalSkills = Directory(
+        p.join(repoRoot.path, 'skills'),
+      ).resolveSymbolicLinksSync();
+
+      expect(
+        p.equals(resolvedLink, canonicalSkills),
+        isTrue,
+        reason:
+            'symlink should resolve to "$canonicalSkills", '
+            'got "$resolvedLink"',
+      );
+    });
+
+    test('every top-level skill is reachable through the plugin symlink', () {
+      final canonicalSkills = Directory(p.join(repoRoot.path, 'skills'));
+      final skillNames = canonicalSkills
+          .listSync()
+          .whereType<Directory>()
+          .map((entity) => p.basename(entity.path))
+          .where(
+            (name) => File(
+              p.join(canonicalSkills.path, name, 'SKILL.md'),
+            ).existsSync(),
+          )
+          .toList();
+
+      expect(
+        skillNames,
+        isNotEmpty,
+        reason: 'expected at least one skill in skills/',
+      );
+
+      for (final name in skillNames) {
+        final viaLink = File(p.join(pluginLink, name, 'SKILL.md'));
+        expect(
+          viaLink.existsSync(),
+          isTrue,
+          reason: 'skill "$name" should be reachable via the plugin symlink',
+        );
+      }
+    });
+  });
+}