feat(auth): 登录异常改为居中弹窗

test/auth/phone_auth_sheet_test.dart

@@ -5,6 +5,7 @@ import 'dart:convert';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:fruitshorts/core/data/models/auth_session.dart';
 import 'package:fruitshorts/core/data/remote/api_client.dart';
 import 'package:fruitshorts/core/data/remote/auth_api.dart';
 import 'package:fruitshorts/core/data/services/auth_controller.dart';
@@ -97,6 +98,64 @@ void main() {
 
     expect(find.text('Enter a valid phone number'), findsOneWidget);
     expect(adapter.requests, isEmpty);
+    expect(find.byKey(const Key('centered-error-dialog')), findsNothing);
+  });
+
+  testWidgets('should_show_centered_dialog_when_otp_request_fails', (
+    tester,
+  ) async {
+    final api = _FailingPhoneAuthApi(sendOtpMessage: 'Too many OTP requests');
+    final auth = AuthController(api, AuthSessionStore());
+    await _pumpHost(tester, auth);
+    await tester.tap(find.byKey(const Key('open-phone-sheet')));
+    await tester.pumpAndSettle();
+    await tester.enterText(
+      find.byKey(const Key('auth-phone-number')),
+      '08123456789',
+    );
+
+    await tester.tap(find.byKey(const Key('auth-send-code')));
+    await tester.pumpAndSettle();
+
+    expect(find.byKey(const Key('centered-error-dialog')), findsOneWidget);
+    expect(find.text('Login failed'), findsOneWidget);
+    expect(find.text('Too many OTP requests'), findsOneWidget);
+    expect(api.sendOtpCalls, 1);
+    expect(
+      tester
+          .widget<TextButton>(find.byKey(const Key('auth-send-code')))
+          .onPressed,
+      isNotNull,
+    );
+  });
+
+  testWidgets('should_show_centered_dialog_when_phone_login_fails', (
+    tester,
+  ) async {
+    final api = _FailingPhoneAuthApi(loginMessage: 'Invalid verification code');
+    final auth = AuthController(api, AuthSessionStore());
+    await _pumpHost(tester, auth);
+    await tester.tap(find.byKey(const Key('open-phone-sheet')));
+    await tester.pumpAndSettle();
+    await tester.enterText(
+      find.byKey(const Key('auth-phone-number')),
+      '08123456789',
+    );
+    await tester.enterText(find.byKey(const Key('auth-phone-code')), '123456');
+
+    await tester.tap(find.byKey(const Key('auth-phone-submit')));
+    await tester.pumpAndSettle();
+
+    expect(find.byKey(const Key('centered-error-dialog')), findsOneWidget);
+    expect(find.text('Login failed'), findsOneWidget);
+    expect(find.text('Invalid verification code'), findsOneWidget);
+    expect(api.loginWithPhoneCalls, 1);
+    expect(
+      tester
+          .widget<FilledButton>(find.byKey(const Key('auth-phone-submit')))
+          .onPressed,
+      isNotNull,
+    );
   });
 
   testWidgets('should_keep_code_above_ios_keyboard', (tester) async {
@@ -132,6 +191,45 @@ void main() {
   });
 }
 
+class _FailingPhoneAuthApi extends AuthApi {
+  _FailingPhoneAuthApi({
+    this.sendOtpMessage = 'otp failed',
+    this.loginMessage = 'login failed',
+  }) : super(
+         ApiClient(
+           baseUrl: 'http://127.0.0.1:1',
+           adapter: FakeHttpAdapter((_) async => FakeHttpResponse('{}', 500)),
+         ),
+       );
+
+  final String sendOtpMessage;
+  final String loginMessage;
+  int sendOtpCalls = 0;
+  int loginWithPhoneCalls = 0;
+
+  @override
+  Future<void> sendOtp({
+    required String target,
+    required String scene,
+    required String deviceId,
+  }) async {
+    sendOtpCalls++;
+    throw ApiException(429, sendOtpMessage);
+  }
+
+  @override
+  Future<AuthSession> loginWithPhone({
+    required String target,
+    required String code,
+    required String deviceId,
+    String platform = '',
+    String appVersion = '',
+  }) async {
+    loginWithPhoneCalls++;
+    throw ApiException(401, loginMessage);
+  }
+}
+
 Future<void> _pumpHost(WidgetTester tester, AuthController auth) {
   return tester.pumpWidget(
     MultiProvider(