Riverpod to BlocSignal: Incremental Migration and Zero-Codegen Signals for Flutter

Introduction: Combining Riverpod Safety with Zero Codegen

If you've been building Flutter apps with Riverpod, you already know the joy of compile-time provider safety, auto-disposal, and synchronous notification propagation via ProviderListenable. Riverpod fundamentally raised the bar for Flutter state management.

However, as projects grow, many Riverpod developers run into familiar friction points:

• Code Generation Overhead: Depending heavily on riverpod_generator and waiting on build_runner watches during rapid UI iteration.
• Complex Provider Trees: Managing nested ProviderScope overrides and .family cache eviction policies when scaling large teams.
• All-or-Nothing Migration Concerns: Wanting to trial new reactive primitives or event-driven BLoC architectures without rewriting an entire codebase.

What if you could combine the compile-time safety and synchronous reactivity you love in Riverpod with zero code generation, fine-grained signal graph reactivity, and the ability to trial or migrate incrementally screen-by-screen?

Enter BlocSignal and bloc_signals_riverpod.

The Core Ergonomics: Riverpod Notifier vs. CubitSignal

Let's compare the classic Todos application—one of the benchmark examples in the official Riverpod monorepo—ported directly to BlocSignal.

The Riverpod Approach (Requires @riverpod & build_runner)

In modern Riverpod, creating a todo list with reactive filtering typically involves a generated Notifier and separate provider getters or ref.watch selectors:

@riverpod
class TodoList extends _$TodoList {
  @override
  List<Todo> build() => const [];

  void addTodo(String description) {
    state = [...state, Todo(id: DateTime.now().toString(), description: description)];
  }

  void toggle(String id) {
    state = [
      for (final todo in state)
        if (todo.id == id) todo.copyWith(completed: !todo.completed) else todo
    ];
  }
}

// Derived filter provider
@riverpod
List<Todo> filteredTodos(Ref ref) {
  final todos = ref.watch(todoListProvider);
  final filter = ref.watch(todoFilterProvider);
  return switch (filter) {
    TodoFilter.all => todos,
    TodoFilter.active => todos.where((t) => !t.completed).toList(),
    TodoFilter.completed => todos.where((t) => t.completed).toList(),
  };
}

The BlocSignal Approach (100% Pure Dart 3, No Codegen)

With BlocSignal, your state container is a standard handwritten Dart class (CubitSignal<List<Todo>>). Reactive derivations like filteredTodos and uncompletedCount are declared inline using signals computed():

import 'package:bloc_signals/bloc_signals.dart';
import 'package:flutter/foundation.dart';
import 'package:signals_core/signals_core.dart';

class TodosCubit extends CubitSignal<List<Todo>> {
  // Pass `equals: listEquals` to enforce value-based list equality for state de-duplication!
  TodosCubit([List<Todo> initialTodos = const []])
      : super(initialState: initialTodos, equals: listEquals) {
    // 1. Reactive filter signal
    filter = signal(TodoFilter.all);

    // 2. Synchronously derived computed signals
    filteredTodos = computed(() {
      return switch (filter.value) {
        TodoFilter.all => stateValue,
        TodoFilter.active => stateValue.where((t) => !t.completed).toList(),
        TodoFilter.completed => stateValue.where((t) => t.completed).toList(),
      };
    });

    uncompletedCount = computed(() => stateValue.where((t) => !t.completed).length);
  }

  late final Signal<TodoFilter> filter;
  late final ReadonlySignal<List<Todo>> filteredTodos;
  late final ReadonlySignal<int> uncompletedCount;

  void addTodo(String description) {
    emit([...stateValue, Todo(id: DateTime.now().toString(), description: description)]);
  }

  void toggle(String id) {
    emit([
      for (final todo in stateValue)
        if (todo.id == id) todo.copyWith(completed: !todo.completed) else todo
    ]);
  }

  void setFilter(TodoFilter newFilter) => filter.value = newFilter;

  @override
  Future<void> close() async {
    filter.dispose();
    filteredTodos.dispose();
    uncompletedCount.dispose();
    await super.close();
  }
}

What Changed?

1. No build_runner: No .g.dart generated files, no background watchers, no build step delays.
2. Built-In Custom Equality (equals: listEquals): Because Dart List instances don't override == by default, passing equals: listEquals configures the underlying signal graph to de-duplicate state emissions based on list content equality.
3. Fine-Grained Signal Graph: Updates to filter.value or calling emit(...) re-evaluate computed() derivations synchronously and notify only dependent widgets.
4. Explicit Container Lifecycles: Disposing the cubit disposes its internal signals automatically.

Zero Risk: Incremental Trial & Bidirectional Interop

You do not need to rewrite your application to try BlocSignal. With the bloc_signals_riverpod package, you can seamlessly bridge the two frameworks in both directions.

dependencies:
  bloc_signals: ^1.0.0
  bloc_signals_flutter: ^1.0.0
  bloc_signals_riverpod: ^1.0.0

Option A: Expose a BlocSignal / CubitSignal to Existing Riverpod Widgets

Want to write a new feature or state controller with BlocSignal, but keep your existing Riverpod UI layer (ConsumerWidget, WidgetRef)?

Simply call .toProvider():

import 'package:bloc_signals_riverpod/bloc_signals_riverpod.dart';

// Create your new BlocSignal or CubitSignal
final todosCubit = TodosCubit();

// Convert it directly into a Riverpod NotifierProvider!
final todosProvider = todosCubit.toProvider();

// Now consume it anywhere in existing Riverpod widgets:
class LegacyRiverpodWidget extends ConsumerWidget {
  const LegacyRiverpodWidget({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    // Rebuilds reactively whenever todosCubit emits!
    final todos = ref.watch(todosProvider);

    return ListView.builder(
      itemCount: todos.length,
      itemBuilder: (context, i) => Text(todos[i].description),
    );
  }
}

Option B: Adapt an Existing Riverpod Provider into BlocSignal

Have a legacy Riverpod provider that you need to read from a new BlocSignalBuilder widget?

Use .toBlocSignal(ref):

import 'package:bloc_signals_riverpod/bloc_signals_riverpod.dart';

class NewFeatureWidget extends ConsumerWidget {
  const NewFeatureWidget({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    // Adapt any Riverpod ProviderListenable into a BlocSignal container!
    // Automatically binds ref.onDispose to close the container when disposed.
    final todosBloc = legacyRiverpodProvider.toBlocSignal(ref);

    return BlocSignalBuilder<BlocSignalBase<List<Todo>>, List<Todo>>(
      bloc: todosBloc,
      builder: (context, todos) {
        return ListView.builder(
          itemCount: todos.length,
          itemBuilder: (context, i) => Text(todos[i].description),
        );
      },
    );
  }
}

Converting AsyncValue <-> AsyncState

bloc_signals_riverpod also provides extension methods to map seamlessly between Riverpod's AsyncValue and Signals' AsyncState:

// Riverpod AsyncValue to Signals AsyncState
final asyncState = riverpodAsyncValue.toAsyncState();

// Signals AsyncState to Riverpod AsyncValue
final asyncValue = signalsAsyncState.toAsyncValue();

Explore the Official Riverpod Ports on blocsignal.dev

To prove the DX gains and side-by-side equivalence, we've ported canonical state management examples directly from the official rrousselGit/riverpod monorepo into the BlocSignal open-source repository:

1. 📝 Riverpod Todos (examples/riverpod_todos):
   • Replaces @riverpod codegen and Notifier with CubitSignal<List<Todo>> and synchronous computed() signals for reactive filter tabs and stats.
2. 🔍 Pub.dev Package Search (examples/riverpod_pub):
   • Replaces Riverpod AsyncNotifier with BlocSignal and a streamless restartable() event transformer that automatically cancels in-flight API requests on keypresses without Rx streams.
3. 🦸 Marvel Character Browser (examples/riverpod_marvel):
   • Demonstrates API pagination, character search, and widget tree scoping via BlocSignalProvider.value.

Explore all 20 side-by-side benchmark ports across BLoC, Signals, and Riverpod live at blocsignal.dev/#ported-examples!

Built-In AI Agent Skills for Automated Migration

If you use AI coding assistants like Antigravity, Gemini, Cursor, or GitHub Copilot, BlocSignal publishes a dedicated Agent Plugin skill bundle (riverpod_migration.md).

When your AI assistant inspects a project with BlocSignal skills enabled, it automatically understands:

• How to map StateNotifierProvider / NotifierProvider to CubitSignal;
• How to preserve auto-disposal and cancellation contracts;
• How to refactor ConsumerWidget rebuild boundaries to BlocSignalBuilder or SignalBuilder;
• How to apply bloc_signals_riverpod interop adapters during multi-phase refactoring.

Summary

You don't need to throw away your existing architecture to enjoy the speed, simplicity, and zero-codegen elegance of reactive signals.

With bloc_signals_riverpod, you can trial BlocSignal on a single screen today, bridge your existing Riverpod providers seamlessly, and upgrade your developer experience at your own pace.

• 🌐 Website & Comparison Benchmarks: blocsignal.dev
• 📦 Pub.dev Packages: bloc_signals | bloc_signals_flutter | bloc_signals_riverpod
• 🐙 GitHub Repository: RandalSchwartz/BlocSignal