WIP - Implement code freeze mechanism at autosubmit

auto_submit/hook/build.dart

@@ -0,0 +1,30 @@
+// Copyright 2026 The Flutter Authors. 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:native_assets_cli/native_assets_cli.dart';
+
+void main(List<String> args) async {
+  await build(args, (config, output) async {
+    // 1. Read the source file (the code freeze config)
+    final configFile = File('lib/configuration/code_freeze.yaml');
+    final content = await configFile.readAsString();
+
+    // 2. Define the path for the generated code
+    final outputFile = File('lib/src/generated_config.dart');
+
+    // 3. Write the file as a raw string constant
+    await outputFile.writeAsString("""
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// Generated by hook/build.dart
+
+const String codeFreezeConfigContent =
+    r'''$content''';
+""");
+
+    // 4. Tell Dart that this hook depends on the config file
+    output.addDependency(configFile.uri);
+  });
+}

auto_submit/lib/configuration/code_freeze.yaml

@@ -0,0 +1,7 @@
+flutter/flutter:
+  frozen_labels:
+    - "f: material design"
+    - "f: cupertino"
+  frozen_paths:
+    - "packages/flutter/lib/src/material/"
+    - "packages/flutter/lib/src/cupertino/"

auto_submit/lib/configuration/code_freeze_configuration.dart

@@ -0,0 +1,90 @@
+// Copyright 2026 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:github/github.dart';
+import 'package:json_annotation/json_annotation.dart';
+import 'package:meta/meta.dart';
+import 'package:yaml/yaml.dart';
+
+part 'code_freeze_configuration.g.dart';
+
+/// Configuration for repository-specific code freezes.
+@JsonSerializable(explicitToJson: true)
+@immutable
+final class CodeFreezeConfiguration {
+  const CodeFreezeConfiguration([this.repoFreezeCriteria = const <String, FreezeCriteria>{}]);
+
+  /// A mapping of repository slugs to their freeze criteria.
+  @JsonKey(name: 'repoFreezeCriteria')
+  final Map<String, FreezeCriteria> repoFreezeCriteria;
+
+  /// Parses the configuration from a YAML string.
+  factory CodeFreezeConfiguration.fromYaml(String yaml) {
+    final yamlDoc = loadYaml(yaml) as YamlMap;
+    final map = <String, dynamic>{
+      'repoFreezeCriteria': yamlDoc.asMap,
+    };
+    return CodeFreezeConfiguration.fromJson(map);
+  }
+
+  /// Creates [CodeFreezeConfiguration] from a [json] object.
+  factory CodeFreezeConfiguration.fromJson(Map<String, dynamic> json) => _$CodeFreezeConfigurationFromJson(json);
+
+  /// Converts [CodeFreezeConfiguration] to a [json] object.
+  Map<String, dynamic> toJson() => _$CodeFreezeConfigurationToJson(this);
+
+  /// Returns the freeze criteria for the given [slug].
+  FreezeCriteria getFreezeCriteria(RepositorySlug slug) {
+    return repoFreezeCriteria[slug.fullName] ?? const FreezeCriteria();
+  }
+}
+
+/// Criteria used to determine if a PR is affected by a code freeze.
+@JsonSerializable()
+@immutable
+final class FreezeCriteria {
+  const FreezeCriteria({
+    this.frozenLabels = const <String>{},
+    this.frozenPaths = const <String>{},
+  });
+
+  final Set<String> frozenLabels;
+  final Set<String> frozenPaths;
+
+  /// Creates [FreezeCriteria] from a [json] object.
+  factory FreezeCriteria.fromJson(Map<String, dynamic> json) => _$FreezeCriteriaFromJson(json);
+
+  /// Converts [FreezeCriteria] to a [json] object.
+  Map<String, dynamic> toJson() => _$FreezeCriteriaToJson(this);
+
+  bool get isEmpty => frozenLabels.isEmpty && frozenPaths.isEmpty;
+}
+
+extension _YamlMapToMap on YamlMap {
+  Map<String, dynamic> get asMap => <String, dynamic>{
+    for (final MapEntry(:key, :value) in entries)
+      if (value is YamlMap)
+        '$key': value.asMap
+      else if (value is YamlList)
+        '$key': value.asList
+      else if (value is YamlScalar)
+        '$key': value.value
+      else
+        '$key': value,
+  };
+}
+
+extension _YamlListToList on YamlList {
+  List<dynamic> get asList => <dynamic>[
+    for (final node in nodes)
+      if (node is YamlMap)
+        node.asMap
+      else if (node is YamlList)
+        node.asList
+      else if (node is YamlScalar)
+        node.value
+      else
+        node,
+  ];
+}

auto_submit/lib/service/config.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:convert';
+import 'dart:io';
 import 'dart:typed_data';
 
 import 'package:cocoon_server/bigquery.dart';
@@ -16,9 +17,11 @@ import 'package:neat_cache/cache_provider.dart';
 import 'package:neat_cache/neat_cache.dart';
 import 'package:retry/retry.dart';
 
+import '../configuration/code_freeze_configuration.dart';
 import '../configuration/repository_configuration.dart';
 import '../configuration/repository_configuration_manager.dart';
 import '../foundation/providers.dart';
+import '../src/generated_config.dart';
 import 'github_service.dart';
 
 class CocoonGitHubRequestException implements Exception {
@@ -49,9 +52,13 @@ class Config {
       this,
       cache,
     );
+    codeFreezeConfiguration = CodeFreezeConfiguration.fromYaml(
+      codeFreezeConfigContent,
+    );
   }
 
   late RepositoryConfigurationManager repositoryConfigurationManager;
+  late CodeFreezeConfiguration codeFreezeConfiguration;
 
   /// Project/GCP constants
   static const String flutter = 'flutter';

auto_submit/lib/validations/code_freeze.dart

@@ -0,0 +1,64 @@
+// Copyright 2026 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:github/github.dart' as github;
+
+import '../model/auto_submit_query_result.dart';
+import 'validation.dart';
+
+/// Validates that a pull request is not affected by an active code freeze.
+class CodeFreeze extends Validation {
+  CodeFreeze({required super.config});
+
+  @override
+  Future<ValidationResult> validate(
+    QueryResult result,
+    github.PullRequest pr,
+  ) async {
+    final slug = pr.base!.repo!.slug();
+    final criteria = config.codeFreezeConfiguration.getFreezeCriteria(slug);
+
+    if (criteria.isEmpty) {
+      return ValidationResult(true, Action.IGNORE_FAILURE, '');
+    }
+
+    // Check labels first as it is cheaper.
+    final prLabels =
+        pr.labels?.map((label) => label.name).toSet() ?? <String>{};
+    final matchedLabels = criteria.frozenLabels.intersection(prLabels);
+    if (matchedLabels.isNotEmpty) {
+      final message =
+          'This pull request is blocked due to an active code freeze for the following labels: ${matchedLabels.join(", ")}.';
+      return ValidationResult(false, Action.REMOVE_LABEL, message);
+    }
+
+    // Check paths if frozen paths are defined.
+    if (criteria.frozenPaths.isNotEmpty) {
+      final githubService = await config.createGithubService(slug);
+      final files = await githubService.getPullRequestFiles(slug, pr);
+      final matchedPaths = <String>{};
+
+      for (final file in files) {
+        final filename = file.filename;
+        if (filename == null) continue;
+        for (final frozenPath in criteria.frozenPaths) {
+          if (filename.startsWith(frozenPath)) {
+            matchedPaths.add(frozenPath);
+          }
+        }
+      }
+
+      if (matchedPaths.isNotEmpty) {
+        final message =
+            'This pull request is blocked due to an active code freeze for the following paths: ${matchedPaths.join(", ")}.';
+        return ValidationResult(false, Action.REMOVE_LABEL, message);
+      }
+    }
+
+    return ValidationResult(true, Action.IGNORE_FAILURE, '');
+  }
+
+  @override
+  String get name => 'CodeFreeze';
+}

auto_submit/lib/validations/validation_filter.dart

@@ -8,6 +8,7 @@ import '../service/process_method.dart';
 import 'approval.dart';
 import 'base_commit_date_allowed.dart';
 import 'ci_successful.dart';
+import 'code_freeze.dart';
 import 'empty_checks.dart';
 import 'mergeable.dart';
 import 'required_check_runs.dart';
@@ -50,6 +51,7 @@ class PullRequestValidationFilter implements ValidationFilter {
 
     validationsToRun.add(BaseCommitDateAllowed(config: config));
     validationsToRun.add(Approval(config: config));
+    validationsToRun.add(CodeFreeze(config: config));
     // If we are running ci then we need to check the checkRuns and make sure
     // there are check runs created.
     if (repositoryConfiguration.runCi) {
@@ -72,6 +74,7 @@ class EmergencyValidationFilter implements ValidationFilter {
   @override
   Set<Validation> getValidations() => {
     Approval(config: config),
+    CodeFreeze(config: config),
     Mergeable(config: config),
   };
 }
@@ -87,6 +90,7 @@ class RevertRequestValidationFilter implements ValidationFilter {
   @override
   Set<Validation> getValidations() => {
     Approval(config: config),
+    CodeFreeze(config: config),
     RequiredCheckRuns(config: config),
     Mergeable(config: config),
   };

auto_submit/pubspec.yaml

@@ -45,6 +45,7 @@ dev_dependencies:
   dart_flutter_team_lints: 3.5.2
   json_serializable: ^6.9.4
   mockito: ^5.4.6
+  native_assets_cli: ^0.18.0
   test: ^1.26.3
 
 builders:

auto_submit/test/configuration/code_freeze_configuration_test.dart

@@ -0,0 +1,56 @@
+// Copyright 2026 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:auto_submit/configuration/code_freeze_configuration.dart';
+import 'package:github/github.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('CodeFreezeConfiguration', () {
+    test('parses YAML correctly', () {
+      const yaml = '''
+flutter/flutter:
+  frozen_labels:
+    - "f: material design"
+    - "f: cupertino"
+  frozen_paths:
+    - "packages/flutter/lib/src/material/"
+    - "packages/flutter/lib/src/cupertino/"
+flutter/packages:
+  frozen_labels:
+    - "blocked"
+''';
+      final config = CodeFreezeConfiguration.fromYaml(yaml);
+
+      final flutterCriteria = config.getFreezeCriteria(
+        RepositorySlug('flutter', 'flutter'),
+      );
+      expect(
+        flutterCriteria.frozenLabels,
+        containsAll(['f: material design', 'f: cupertino']),
+      );
+      expect(
+        flutterCriteria.frozenPaths,
+        containsAll([
+          'packages/flutter/lib/src/material/',
+          'packages/flutter/lib/src/cupertino/',
+        ]),
+      );
+
+      final packagesCriteria = config.getFreezeCriteria(
+        RepositorySlug('flutter', 'packages'),
+      );
+      expect(packagesCriteria.frozenLabels, contains('blocked'));
+      expect(packagesCriteria.frozenPaths, isEmpty);
+    });
+
+    test('returns empty criteria for unknown slug', () {
+      final config = CodeFreezeConfiguration.fromYaml('{}');
+      final criteria = config.getFreezeCriteria(
+        RepositorySlug('unknown', 'unknown'),
+      );
+      expect(criteria.isEmpty, isTrue);
+    });
+  });
+}