DDD Context Generator

Generate complete Domain-Driven Design bounded contexts with all 4 architectural layers (Domain, Application, Infrastructure, Presentation) for Bun.js + Express + routing-controllers backend applications.

What This Skill Does

This skill generates production-ready code for a complete bounded context following DDD and Clean Architecture principles. It creates:

• Domain Layer: Entities, value objects, repository interfaces, domain events, and errors
• Application Layer: Use cases with dependency injection and event listeners
• Infrastructure Layer: Mongoose models, repository implementations, and mappers
• Presentation Layer: Request DTOs, response serializers, controllers with decorator-based routing and Swagger documentation

When to Use This Skill

Use this skill when you need to:

• Create a new business capability from scratch
• Scaffold a complete context with CRUD operations
• Add a new bounded context to your DDD backend
• Generate a full feature with all architectural layers

Examples:

• "Create an Order context with CRUD operations"
• "Generate a Product context with inventory management"
• "Build a Payment context with transaction handling"

How It Works

Step 1: Requirements Gathering

The skill will ask you to clarify:

• Context name (e.g., "User", "Product", "Order")
• Required operations (CRUD, custom use cases)
• Business rules and invariants
• Required value objects
• Domain events needed

Step 2: Code Generation

The skill generates code in this order:

1. Directory Structure - Shows complete file tree
2. Domain Layer - Pure business logic with zero dependencies

- Value objects (immutable, validated) - Domain errors (with error codes) - Domain events (past tense naming) - Entities (factory methods, encapsulation) - Repository interfaces (domain contracts) - Barrel export (index.ts)

1. Application Layer - Use cases and orchestration

- Use cases (@injectable, execute method) - Event listeners (handle domain events) - Barrel export (index.ts)

1. Infrastructure Layer - Persistence implementation

- Mongoose models (with TypeScript interfaces) - Mappers (domain ↔ persistence conversion) - Repository implementations (@injectable)

1. Presentation Layer - HTTP API

- Request DTOs (class-validator decorators) - Response serializers (@JSONSchema decorators) - Controllers (@injectable, decorator-based routing with @JsonController)

1. Integration Code

- DI container registration - Event listener registration - Route registration

Step 3: Verification

The skill provides a checklist to verify:

• All layers properly structured
• Dependency rules followed
• Proper decorators applied
• Integration code provided

Architecture Requirements

This skill follows the patterns defined in the project's CLAUDE.md:

Tech Stack

• Runtime: Bun.js
• Framework: Express + routing-controllers
• Database: MongoDB with Mongoose
• Validation: class-validator
• DI Container: tsyringe
• Documentation: routing-controllers-openapi + Swagger UI

Dependency Rule

Presentation → Application → Domain
      ↓            ↓
  Infrastructure

• Domain has ZERO external dependencies
• Application depends only on Domain
• Infrastructure implements Domain interfaces
• Presentation depends on Application and Domain

Key Patterns

Entity Pattern:

export class EntityName {
  private constructor(...) {}

  static create(data): EntityName {
    // Validation and creation
  }

  static reconstitute(data): EntityName {
    // Load from database
  }

  // Getters and business methods
}

Value Object Pattern:

export class ValueObject {
  private readonly value: string;

  private constructor(value: string) {
    this.value = value;
  }

  static create(value: string): ValueObject {
    // Validation
    return new ValueObject(value);
  }

  equals(other: ValueObject): boolean {
    return this.value === other.value;
  }
}

UseCase Pattern:

@injectable()
export class ActionEntityUseCase {
  constructor(
    @inject('IEntityRepository')
    private readonly repo: IEntityRepository
  ) {}

  async execute(input: Input): Promise<Output> {
    // Business logic
    await eventBus.emit('EventName', event);
    return output;
  }
}

API Pattern:

// Versioned routes with Swagger
new Elysia({ prefix: '/v1/entities' })
  .post('/', controller.create.bind(controller), {
    body: CreateSchema,
    detail: {
      summary: 'Create entity',
      tags: ['Entities'],
      responses: { 201: {}, 400: {}, 409: {} }
    }
  })

Generated Structure

/src/contexts/{ContextName}/
├── domain/
│   ├── entities/
│   │   └── {entity}.entity.ts
│   ├── value-objects/
│   │   └── {vo}.vo.ts
│   ├── repositories/
│   │   └── {entity}.repository.interface.ts
│   ├── events/
│   │   └── {event}.event.ts
│   ├── errors/
│   │   └── {context}.errors.ts
│   └── index.ts
├── application/
│   ├── usecases/
│   │   ├── create-{entity}.usecase.ts
│   │   ├── find-{entity}.usecase.ts
│   │   ├── update-{entity}.usecase.ts
│   │   └── delete-{entity}.usecase.ts
│   ├── listeners/
│   │   └── {event}.listener.ts
│   └── index.ts
├── infrastructure/
│   ├── models/
│   │   └── {entity}.model.ts
│   ├── repositories/
│   │   └── {entity}.repository.ts
│   └── mappers/
│       └── {entity}.mapper.ts
└── presentation/
    ├── schemas/
    │   ├── create-{entity}.schema.ts
    │   ├── update-{entity}.schema.ts
    │   ├── query-{entity}.schema.ts
    │   └── {entity}-response.schema.ts
    ├── {context}.controller.ts
    └── {context}.routes.ts

Code Quality Standards

All generated code follows:

• Type Safety: No any types, use unknown if needed
• Naming: PascalCase classes, camelCase methods, UPPERSNAKECASE constants
• Exports: Named exports only (no default exports)
• Decorators: @injectable() on all DI classes
• Error Handling: Domain errors in domain, HTTP exceptions in presentation
• Documentation: Minimal code comments, comprehensive Swagger docs

Integration Instructions

After generation, you need to:

1. Register repository in DI container (/src/global/container/container.ts):

container.registerSingleton<IEntityRepository>(
  'IEntityRepository',
  EntityRepository
);

1. Register routes (/src/main.ts):

import { registerEntityRoutes } from '@/contexts/entity/presentation/entity.routes';
app.use(registerEntityRoutes());

1. Register event listeners (/src/main.ts):

import { EntityCreatedListener } from '@/contexts/entity/application';
const listener = container.resolve(EntityCreatedListener);
eventBus.on('EntityCreated', listener.handle.bind(listener));

Before Using This Skill

Ensure you have:

1. Read the main CLAUDE.md architecture guide
2. Understanding of DDD and Clean Architecture principles
3. Familiarity with the tech stack (Bun.js, Elysia.js, MongoDB)

Related Skills

• ddd-entity-generator: Generate individual domain entities
• ddd-usecase-generator: Generate application layer use cases
• ddd-api-generator: Generate presentation layer APIs
• ddd-validator: Validate DDD compliance after generation