MobX + Clean Architecture + Firebase — Reactive State Done Right

MobX + Clean Architecture + Firebase gives you reactive @observable state behind Clean data / domain / presentation layers, with Firebase Auth email-password wired in. It's a valid Flutter stack — just less common than Riverpod or Bloc. FlutterInit generates the stores, build_runner config, and Firebase Auth service so you're not hand-rolling codegen.

What This Stack Generates

Select MobX + Clean Architecture + Firebase and you get:

• Clean feature folders — lib/src/features/auth/{data,domain,presentation}/
• MobX stores — AuthStore / SessionStore with @observable + @action, plus mobx, flutter_mobx, and build_runner
• Firebase — AuthService over signInWithEmailAndPassword, plus Google Services setup docs
• go_router — session-aware redirects

Honest caveat up front: most Flutter job posts and tutorials assume Riverpod or Bloc. Pick MobX because you want the reactive model, not because it's the default community pick.

Project Structure

On Clean / Feature-First, MobX stores land under presentation/providers/ (auth_store.dart, session_store.dart). On MVVM, they land under lib/src/ui/auth/stores/ instead.

Observables, Actions, Reactions

MobX's contract is simple:

• @observable — state the UI can react to (isLoading, user, form fields)
• @action — the only place you mutate observables (login, logout, toggle loading)
• Reactions — Observer widgets (via flutter_mobx) rebuild when tracked observables change

You don't manually call notifyListeners(). Codegen wires the tracking.

part 'auth_store.g.dart';

class AuthStore = AuthStoreBase with _$AuthStore;

abstract class AuthStoreBase with Store {
  final AuthRepository _repository;

  AuthStoreBase({required AuthRepository repository}) : _repository = repository;

  @observable
  bool isLoading = false;

  @action
  void login({
    required BuildContext context,
    required String email,
    required String password,
  }) async {
    isLoading = true;

    final result = await _repository.login(email: email, password: password);

    isLoading = false;
    result.fold(
      (failure) {
        if (context.mounted) {
          showToast(context, message: failure.message, status: 'error');
        }
      },
      (_) {
        if (context.mounted) context.go(AppRoutes.home);
      },
    );
  }
}

Screens wrap reactive bits in Observer:

Observer(
  builder: (_) => ElevatedButton(
    onPressed: store.isLoading ? null : () => store.login(...),
    child: store.isLoading
        ? const CircularProgressIndicator()
        : const Text('Sign in'),
  ),
)

Codegen — build_runner Is Required

MobX stores need generated mixins (_$AuthStore). FlutterInit adds mobx, flutter_mobx, mobx_codegen, and build_runner to pubspec.yaml. After you edit a store:

dart run build_runner build --delete-conflicting-outputs

Skip this step and you'll get missing part / _$AuthStore errors. Re-run after every store change. Same story as Hive adapters or AutoRoute — this stack is codegen-heavy by design.

Domain and Data Still Stay Clean

The store depends on AuthRepository — not Firebase. Domain stays SDK-free:

abstract class AuthRepository {
  Stream<AppUser?> get onAuthStateChanged;

  FutureEither<AppUser> login({
    required String email,
    required String password,
  });

  FutureEither<void> logout();
}

Data implements it via AuthService → FirebaseAuth.signInWithEmailAndPassword. Drop in google-services.json / GoogleService-Info.plist per SETUP.md. That's the Firebase edge; everything above it stays testable with a fake repository.

When to Choose This vs Alternatives

Pick MobX + Clean + Firebase when:

• Your team already thinks in observables/actions (web MobX, or prior Flutter MobX apps)
• You want Clean feature folders but prefer MobX ergonomics over Riverpod providers
• You're fine running build_runner as part of the daily loop

Skip it when:

• You want the most hireable Flutter stack — prefer Riverpod + Clean + Firebase
• You want zero codegen for state — Provider or Riverpod without code generation is lighter
• You're new to Clean Architecture itself — start with the Clean Architecture generated guide, then layer MobX once the folders make sense

MobX isn't wrong in Flutter. It's just quieter. Generate it when the reactive model is a deliberate choice, not a default.

Ready to Generate?

Open the dashboard, select Clean + MobX + Firebase + go_router, run build_runner once after unzip, and you've got reactive stores sitting on Clean layers with Firebase Auth ready for email-password.