Architecture

MVVM Pattern

Same architecture as the Parents app — each feature module follows Model-View-ViewModel:

modules/
└── {feature}/
    ├── model/           # Data classes
    ├── view/            # Screens
    ├── viewmodel/       # ChangeNotifier providers
    └── services/        # API calls

GetIt Service Locator

// service_locator.dart
final getIt = GetIt.instance;

Future<void> setupServiceLocator() async {
  // Network
  getIt.registerLazySingleton<DioClient>(() => DioClient());

  // Services
  getIt.registerLazySingleton<AuthService>(() => AuthService(getIt<DioClient>()));
  getIt.registerLazySingleton<AttendanceService>(() => AttendanceService(getIt<DioClient>()));
  getIt.registerLazySingleton<ExamService>(() => ExamService(getIt<DioClient>()));
  // ... more services

  // ViewModels
  getIt.registerFactory<AuthViewModel>(() => AuthViewModel(getIt<AuthService>()));
  getIt.registerFactory<AttendanceViewModel>(() => AttendanceViewModel(getIt<AttendanceService>()));
  getIt.registerFactory<ExamViewModel>(() => ExamViewModel(getIt<ExamService>()));
  // ... more ViewModels
}

BaseProvider

Same BaseProvider mixin used as in the Parents app:

abstract class BaseProvider extends ChangeNotifier {
  bool _isLoading = false;
  String? _errorMessage;

  bool get isLoading => _isLoading;
  String? get errorMessage => _errorMessage;
  bool get hasError => _errorMessage != null;

  void setLoading(bool value) {
    _isLoading = value;
    notifyListeners();
  }

  void setError(String? message) {
    _errorMessage = message;
    notifyListeners();
  }

  Future<T> requestHandler<T>(Future<T> Function() apiCall) async {
    setLoading(true);
    clearError();
    try {
      return await apiCall();
    } catch (e) {
      setError(e.toString());
      rethrow;
    } finally {
      setLoading(false);
    }
  }
}

API Client

Dio client configured in lib/core/network/dio_client.dart with base URL https://dev-api.metaonus.in/teacher. Same 4 interceptors as Parents app: Logger, Auth, TokenRefresh, Evaluation.