Nest Backend Service Builder

Purpose

Build production-ready NestJS backend services using clean architecture, domain-driven design principles, and enterprise patterns.

When to Use

Use this skill when the task involves:

• Creating or modifying NestJS modules, controllers, or services
• Building REST endpoints or GraphQL resolvers
• Implementing WebSocket/Socket.IO real-time features
• Adding DTOs with class-validator validation
• Setting up guards, interceptors, or exception filters
• Writing integration tests for API endpoints

Constraints

• Organize by feature modules, not file type (avoid controllers/, services/ folders)
• Use TypeScript strict mode; define explicit return types
• Apply class-validator decorators on all DTOs
• Use class-transformer for serialization control
• Version APIs explicitly (/v1/resource)
• Follow RFC 7807 Problem Details for error responses
• Apply rate limiting on public endpoints
• Use Helmet for secure HTTP headers

Execution Steps

1. Define module boundary — Identify domain entity and create feature module
2. Create DTOs — Define request/response DTOs with validation decorators
3. Implement service — Business logic with dependency injection
4. Build controller — REST endpoints with proper HTTP methods and status codes
5. Add guards/interceptors — Authentication, authorization, logging as needed
6. Write tests — Integration tests for endpoint contracts
7. Document API — Add Swagger decorators for OpenAPI spec

Examples

Input

Create a user registration endpoint with email validation

Output

// @/modules/users/dto/create-user.dto.ts
import { IsEmail, IsString, MinLength } from 'class-validator';

export class CreateUserDto {
  @IsEmail()
  email: string;

  @IsString()
  @MinLength(8)
  password: string;

  @IsString()
  name: string;
}

// @/modules/users/users.controller.ts
@Controller('v1/users')
export class UsersController {
  constructor(private readonly usersService: UsersService) {}

  @Post('register')
  @HttpCode(HttpStatus.CREATED)
  async register(@Body() dto: CreateUserDto): Promise<UserResponseDto> {
    return this.usersService.register(dto);
  }
}

Related Skills

• database-schema-designer — Design underlying data models
• jest-testing-generator — Write service and controller tests
• senior-code-review — Review API security and patterns

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