State management architecture in Nx

Building scalable Angular applications requires more than just writing good code, it demands architectural decisions that prevent your project from becoming a tangled mess of dependencies. As you saw in few of my last posts, Nx provides a powerful framework for organizing these decisions, especially when it comes to state management patterns.

The challenge of Angular state management at scale

Traditional Angular applications often struggle with state management as they grow. Components become tightly coupled, services proliferate without clear boundaries, and testing becomes increasingly difficult. The typical result is a codebase where changing one feature breaks another, and adding new functionality requires understanding the entire application. Nx addresses these issues through workspace architecture that enforces clear separation of concerns and prevents architectural drift through automated linting rules.

Library-Based architecture

The foundation of effective state management in Nx lies in its library structure. Rather than organizing code by file type (components, services, models), Nx encourages organization by domain and responsibility:

libs/todo-management/todo/
├── data-access/    # HTTP services and external data
├── store/          # NgRx Signal Store implementation / State implementation
├── feature/        # Smart components with business logic aka a feature
├── ui/             # Presentational components
└── util/           # Shared models and types

This structure creates natural boundaries that mirror how state actually flows through your application.

Dependency Direction and Boundaries

The real power of Nx state management architecture comes from its dependency rules. These aren't suggestions you can enforce them through ESLint configuration that prevents architectural violations : https://gillesferrand.com/nx-from-chaos-to-consistency-enforcing-boundaries

This creates isolated business domains that can be developed and tested independently. Store libraries, dedicated for a feature, handle state management and can depend on data-access for external data sources and other stores for composition, but remain isolated from features, and UI concerns. This hierarchy creates unidirectional data flow and prevents the circular dependencies that plague traditional Angular applications.

State Management Implementation

With NgRx Signal Store, state management becomes more declarative and reactive. The store library contains all state logic:

export const TodoStore = signalStore(
  withState(initialState),
  withComputed(({ todos }) => ({
    completedTodos: computed(() => todos().filter(t => t.completed)),
    activeTodos: computed(() => todos().filter(t => !t.completed))
  })),
  withMethods((store, todoService = inject(TodoService)) => ({
    loadTodos: () => {
      // State management logic
    },
    addTodo: (text: string) => {
      // Business logic for adding todos
    }
  }))
);

Full code here : https://github.com/Gillesf31/nx-ngrx-signal-store/blob/main/libs/todo-management/todo/store/src/lib/todo.store.ts

The feature library orchestrates this store with UI components, while data-access libraries handle HTTP communication. Each layer has a single, clear responsibility.

Benefits in Practice

This architecture delivers measurable benefits:

• Build Optimization: Nx's dependency graph allows incremental builds. When you change a UI component, only dependent libraries rebuild, not the entire application / repository.

• Testing Isolation: Each library can be tested independently. UI components can be tested without state management, stores can be tested without HTTP services, and business logic can be tested without UI concerns.

• Team Scalability: Different teams can work on different domains without stepping on each other's code. The dependency rules prevent accidental coupling between features.

• Code Reusability: UI components become truly reusable because they're isolated from business logic. Data access services can be shared across features without coupling.

Migration Strategy

For existing Angular applications, migration to this architecture can happen incrementally. Start by identifying natural domain boundaries in your application, then extract libraries one layer at a time. Begin with utility libraries (models, types), then data access, then stores, and finally features and UI. The ESLint rules can be introduced gradually, allowing you to enforce architecture as you refactor rather than requiring a complete rewrite.

Conclusion

Nx helps you to create and maintain this library architecture which transforms state management from a technical concern into an organizational tool. By enforcing clear boundaries between data access, state management, business logic, and presentation, you create applications that scale with your team and requirements rather than against them. The investment in architectural discipline pays dividends through faster builds, easier testing, and more maintainable code. Most importantly, it prevents the architectural drift that turns promising applications into maintenance nightmares.

Ressources

• https://github.com/Gillesf31/nx-ngrx-signal-store

• https://gillesferrand.com/series/nx

• https://nx.dev/getting-started/tutorials/angular-monorepo-tutorial

• https://www.youtube.com/@nxdevtools