lib/app/app.dart

@@ -5,6 +5,7 @@ import 'package:patbond_flutter/analytics/analytics_route_observer.dart';
 import 'package:patbond_flutter/analytics/analytics_service.dart';
 import 'package:patbond_flutter/analytics/page_view_tracker.dart';
 import 'package:patbond_flutter/analytics/session_tracker.dart';
+import 'package:patbond_flutter/app/app_localization.dart';
 import 'package:patbond_flutter/core/network/api_client.dart';
 import 'package:patbond_flutter/core/network/token_refresher.dart';
 import 'package:patbond_flutter/core/theme/app_theme.dart';
@@ -268,6 +269,11 @@ class _AppState extends State<App> {
       title: 'Patbond',
       debugShowCheckedModeBanner: false,
       theme: buildAppTheme(),
+      // M3.5-01：Material 内置组件中文化（此前未配 delegate，日期选择器等
+      // 全部回退英文兜底）。单语言 zh-CN，不随设备语言回退英文。
+      localizationsDelegates: appLocalizationsDelegates,
+      supportedLocales: appSupportedLocales,
+      locale: appLocale,
       navigatorObservers: [_routeObserver],
       home: ListenableBuilder(
         listenable: sessionManager,

lib/app/app_localization.dart

@@ -0,0 +1,31 @@
+/// 应用本地化配置（M3.5-01）。
+///
+/// 根因备忘：M3 之前 [MaterialApp] 未配任何 `localizationsDelegates`，
+/// Flutter 回退到内置的 `DefaultMaterialLocalizations`（仅英文），导致
+/// 一切 Material 内置组件（日期选择器标题「Select date」、确定/取消
+/// 「OK」/「Cancel」、模式切换 tooltip「Switch to input」、格式报错
+/// 「Invalid format.」）全英文，而业务自绘文案全中文——同一弹窗内中英混排。
+/// 挂上三件套后分别为「选择日期 / 确定 / 取消 / 切换到输入模式 / 格式无效。」。
+///
+/// 这里把三件套 delegate 与 locale 收在一处，供 `App` 与 widget 测试共用：
+/// 测试若只 `pumpWidget(MaterialApp(home: ...))` 而不带 delegate，看到的仍是
+/// 英文兜底，与真机不一致；需要断言中文渲染的测试请一并挂上本文件的常量。
+library;
+
+import 'package:flutter/material.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
+
+/// Material / Cupertino / Widgets 三件套本地化 delegate。
+const List<LocalizationsDelegate<Object>> appLocalizationsDelegates =
+    <LocalizationsDelegate<Object>>[
+      GlobalMaterialLocalizations.delegate,
+      GlobalCupertinoLocalizations.delegate,
+      GlobalWidgetsLocalizations.delegate,
+    ];
+
+/// 简体中文（中国大陆）。M3.5 仅单语言，暂不做语言切换。
+const Locale appLocale = Locale('zh', 'CN');
+
+/// 支持语言列表。仅 zh-CN——避免设备语言为英文时回退到英文，
+/// 造成同一界面内业务中文 + 组件英文的混排。
+const List<Locale> appSupportedLocales = <Locale>[appLocale];

pubspec.lock

@@ -235,6 +235,11 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.0"
+  flutter_localizations:
+    dependency: "direct main"
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   flutter_plugin_android_lifecycle:
     dependency: transitive
     description:
@@ -399,6 +404,14 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  intl:
+    dependency: "direct main"
+    description:
+      name: intl
+      sha256: "3df61194eb431efc39c4ceba583b95633a403f46c9fd341e550ce0bfa50e9aa5"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.20.2"
   jni:
     dependency: transitive
     description:

pubspec.yaml

@@ -43,6 +43,13 @@ dependencies:
   image_picker: ^1.2.0
   # T3-13 媒体上传：原生编解码压缩（长边重采样 + JPEG 质量 + EXIF 方向矫正）。
   flutter_image_compress: ^2.4.0
+  # M3.5-01 中文本地化：Material/Cupertino/Widgets 内置组件文案（日期选择器
+  # 标题、确定/取消、输入模式提示与格式错误）由 Global*Localizations 提供。
+  flutter_localizations:
+    sdk: flutter
+  # flutter_localizations 的日期符号/数字格式底座；显式直接依赖以锁定与 SDK
+  # 一致的版本（避免间接依赖升级悄悄改变格式化行为）。
+  intl: ^0.20.2
 
 dev_dependencies:
   flutter_test:

test/app/app_localization_test.dart

@@ -0,0 +1,49 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:patbond_flutter/app/app.dart';
+import 'package:patbond_flutter/app/app_localization.dart';
+import 'package:patbond_flutter/features/auth/session_manager.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import '../helpers/auth_test_helpers.dart';
+import '../helpers/community_test_helpers.dart';
+import '../helpers/pet_test_helpers.dart';
+
+/// M3.5-01：根 [MaterialApp] 实际挂上 zh-CN 本地化。
+///
+/// 用户桌面实测反馈「日期选择器全英文」的根因就在这里——delegate 一行没配，
+/// Material 静默回退英文兜底。本测试守住这一行不被回删。
+void main() {
+  testWidgets('MaterialApp 挂三件套 delegate + 单语言 zh-CN', (tester) async {
+    SharedPreferences.setMockInitialValues({});
+    final session = SessionManager(store: InMemoryTokenStore())
+      ..markAuthenticated();
+
+    await tester.pumpWidget(
+      App(
+        sessionManager: session,
+        authRepository: FakeAuthRepository(),
+        petsRepository: FakePetsRepository(),
+        communityRepository: FakeCommunityRepository()
+          ..onFeed = (_, _) async => feedPage(const []),
+      ),
+    );
+    await tester.pumpAndSettle();
+
+    final app = tester.widget<MaterialApp>(find.byType(MaterialApp));
+    expect(app.localizationsDelegates, appLocalizationsDelegates);
+    expect(app.supportedLocales, appSupportedLocales);
+    expect(app.locale, const Locale('zh', 'CN'));
+
+    // 运行期实际解析出的 Material 文案为中文（不是 Default* 英文兜底）。
+    final context = tester.element(find.byType(NavigationBar));
+    final l10n = MaterialLocalizations.of(context);
+    expect(l10n.okButtonLabel, '确定');
+    expect(l10n.cancelButtonLabel, '取消');
+    expect(l10n.datePickerHelpText, '选择日期');
+    expect(l10n.dateInputLabel, '输入日期');
+    expect(l10n.inputDateModeButtonLabel, '切换到输入模式');
+    expect(l10n.invalidDateFormatLabel, '格式无效。');
+    expect(l10n.formatMonthYear(DateTime(2026, 9, 10)), '2026年9月');
+  });
+}

test/features/pets/care_reminders_page_test.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:patbond_flutter/core/network/api_exception.dart';
+import 'package:patbond_flutter/app/app_localization.dart';
 import 'package:patbond_flutter/core/theme/app_theme.dart';
 import 'package:patbond_flutter/core/widgets/empty_state_illustration.dart';
 import 'package:patbond_flutter/features/pets/care_reminder_form_page.dart';
@@ -39,6 +40,11 @@ void main() {
     await tester.pumpWidget(
       MaterialApp(
         theme: buildAppTheme(),
+        // M3.5-01：与生产一致挂 zh-CN delegate，日期选择器等内置组件文案
+        // 才是用户真机看到的中文。
+        localizationsDelegates: appLocalizationsDelegates,
+        supportedLocales: appSupportedLocales,
+        locale: appLocale,
         home: const Scaffold(body: Text('详情基底')),
       ),
     );
@@ -206,7 +212,7 @@ void main() {
     );
     await tester.tap(find.text('到期日期'));
     await tester.pumpAndSettle();
-    await tester.tap(find.text('OK'));
+    await tester.tap(find.text('确定'));
     await tester.pumpAndSettle();
     await tester.tap(find.text('保存提醒'));
     await tester.pumpAndSettle();

test/features/pets/vaccination_form_page_test.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:patbond_flutter/core/network/api_exception.dart';
+import 'package:patbond_flutter/app/app_localization.dart';
 import 'package:patbond_flutter/core/theme/app_theme.dart';
 import 'package:patbond_flutter/features/pets/health_record_analytics.dart';
 import 'package:patbond_flutter/features/pets/pet_exceptions.dart';
@@ -36,6 +37,11 @@ void main() {
     await tester.pumpWidget(
       MaterialApp(
         theme: buildAppTheme(),
+        // M3.5-01：与生产一致挂 zh-CN delegate，日期选择器等内置组件文案
+        // 才是用户真机看到的中文。
+        localizationsDelegates: appLocalizationsDelegates,
+        supportedLocales: appSupportedLocales,
+        locale: appLocale,
         home: const Scaffold(body: Text('列表基底')),
       ),
     );
@@ -65,7 +71,7 @@ void main() {
   Future<void> pickDate(WidgetTester tester, String tileLabel) async {
     await tester.tap(find.text(tileLabel));
     await tester.pumpAndSettle();
-    await tester.tap(find.text('OK'));
+    await tester.tap(find.text('确定'));
     await tester.pumpAndSettle();
   }
 

test/features/pets/vaccination_records_page_test.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:patbond_flutter/core/network/api_exception.dart';
+import 'package:patbond_flutter/app/app_localization.dart';
 import 'package:patbond_flutter/core/theme/app_theme.dart';
 import 'package:patbond_flutter/core/widgets/empty_state_illustration.dart';
 import 'package:patbond_flutter/features/pets/health_record_analytics.dart';
@@ -39,6 +40,11 @@ void main() {
     await tester.pumpWidget(
       MaterialApp(
         theme: buildAppTheme(),
+        // M3.5-01：与生产一致挂 zh-CN delegate，日期选择器等内置组件文案
+        // 才是用户真机看到的中文。
+        localizationsDelegates: appLocalizationsDelegates,
+        supportedLocales: appSupportedLocales,
+        locale: appLocale,
         home: const Scaffold(body: Text('详情基底')),
       ),
     );
@@ -166,7 +172,7 @@ void main() {
     await tester.pumpAndSettle();
     await tester.tap(find.text('计划接种日期'));
     await tester.pumpAndSettle();
-    await tester.tap(find.text('OK'));
+    await tester.tap(find.text('确定'));
     await tester.pumpAndSettle();
     await tester.tap(find.text('保存登记'));
     await tester.pumpAndSettle();