[puppy] Introduce a package for misc Dart CLI tools

First tool: for_all_package_dirs to recursively run a command in every
directory that contains pubspec.yaml

.github/workflows/puppy.yml

@@ -0,0 +1,41 @@
+name: package:puppy
+
+permissions: read-all
+
+on:
+  pull_request:
+    branches: [ main ]
+    paths:
+      - '.github/workflows/puppy.yml'
+      - 'pkgs/puppy/**'
+  push:
+    branches: [ main ]
+    paths:
+      - '.github/workflows/puppy.yml'
+      - 'pkgs/puppy/**'
+  schedule:
+    - cron: '0 0 * * 0' # weekly
+
+defaults:
+  run:
+    working-directory: pkgs/puppy
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        sdk: [3.6, dev]
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: dart-lang/setup-dart@e630b99d28a3b71860378cafdc2a067c71107f94
+        with:
+          sdk: ${{ matrix.sdk }}
+
+      - run: dart pub get
+      - run: dart analyze --fatal-infos
+      - run: dart format --output=none --set-exit-if-changed .
+        if: ${{ matrix.sdk == 'dev' }}
+      # TODO: enable when there are tests!
+      #- run: dart test

README.md

@@ -11,6 +11,7 @@ This repository is home to general Dart Ecosystem tools and packages.
 | [corpus](pkgs/corpus/) | A tool to calculate the API usage for a package. |  |
 | [dart_flutter_team_lints](pkgs/dart_flutter_team_lints/) | An analysis rule set used by the Dart and Flutter teams. | [![pub package](https://img.shields.io/pub/v/dart_flutter_team_lints.svg)](https://pub.dev/packages/dart_flutter_team_lints) |
 | [firehose](pkgs/firehose/) | A tool to automate publishing of Pub packages from GitHub actions. | [![pub package](https://img.shields.io/pub/v/firehose.svg)](https://pub.dev/packages/firehose) |
+| [puppy](pkgs/puppy/) | A grab bag of CLI tools for managing Dart code. |  |
 | [repo_manage](pkgs/repo_manage/) | Miscellaneous issue, repo, and PR query tools. |  |
 | [sdk_triage_bot](pkgs/sdk_triage_bot/) | A triage automation tool for dart-lang/sdk issues. |  |
 | [trebuchet](pkgs/trebuchet/) | A tool for moving existing packages into monorepos. |  |

pkgs/puppy/README.md

@@ -0,0 +1,11 @@
+Activate locally using:
+
+```console
+cd <puppy pkg path>
+dart pub global activate --source=path .
+```
+
+### Tools
+
+- `for_all_package_dirs`: runs a command in every directory containing
+  `pubspec.yaml`.

pkgs/puppy/analysis_options.yaml

@@ -0,0 +1 @@
+include: package:dart_flutter_team_lints/analysis_options.yaml

pkgs/puppy/bin/for_all_package_dirs.dart

@@ -0,0 +1,49 @@
+// 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:io';
+
+import 'package:io/ansi.dart';
+import 'package:io/io.dart';
+
+Future<void> main(List<String> args) async {
+  if (args.isEmpty) {
+    print('Need something to execute!');
+    exitCode = ExitCode.usage.code;
+    return;
+  }
+
+  final exe = args.first;
+  final extraArgs = args.skip(1).toList();
+
+  final exits = <String, int>{};
+
+  Future<void> inspectDirectory(Directory dir) async {
+    final pubspecs = dir
+        .listSync()
+        .whereType<File>()
+        .where((element) => element.uri.pathSegments.last == 'pubspec.yaml')
+        .toList();
+
+    if (pubspecs.isNotEmpty) {
+      print(green.wrap(dir.path));
+      final proc = await Process.start(
+        exe,
+        extraArgs,
+        mode: ProcessStartMode.inheritStdio,
+        workingDirectory: dir.path,
+      );
+
+      // TODO(kevmoo): display a summary of results on completion
+      exits[dir.path] = await proc.exitCode;
+    }
+
+    for (var subDir in dir.listSync().whereType<Directory>().where((element) =>
+        !element.uri.pathSegments.any((element) => element.startsWith('.')))) {
+      await inspectDirectory(subDir);
+    }
+  }
+
+  await inspectDirectory(Directory.current);
+}

pkgs/puppy/pubspec.yaml

@@ -0,0 +1,14 @@
+name: puppy
+publish_to: none
+
+environment:
+  sdk: ^3.6.0
+
+dependencies:
+  io: ^1.0.5
+
+dev_dependencies:
+  dart_flutter_team_lints: ^3.0.0
+
+executables:
+  for_all_package_dirs: