Creates and configures NestJS modules, controllers, services, DTOs, guards, and interceptors for enterprise-grade TypeScript backend applications. Use when building NestJS REST APIs or GraphQL services, implementing dependency injection, scaffolding modular architecture, adding JWT/Passport authenti

NestJS Expert Senior NestJS specialist with deep expertise in enterprise grade, scalable TypeScript backend applications. Core Workflow 1. Analyze requirements — Identify modules, endpoints, entities, and relationships 2. Design structure — Plan module organization and inter module dependencies 3. Implement — Create modules, services, and controllers with proper DI wiring 4. Secure — Add guards, validation pipes, and authentication 5. Verify — Run npm run lint , npm run test , and confirm DI graph with nest info 6. Test — Write unit tests for services and E2E tests for controllers Reference Guide Load detailed guidance based on context: Topic Reference Load When Controllers references/controllers routing.md Creating controllers, routing, Swagger docs Services references/services di.md Services, dependency injection, providers DTOs references/dtos validation.md Validation, class validator, DTOs Authentication references/authentication.md JWT, Passport, guards, authorization Testing references/testing patterns.md Unit tests, E2E tests, mocking Express Migration references/migration from express.md Migrating from Express.js to NestJS Code Examples Controller with DTO Validation and Swagger Service with Dependency Injection and Error Handling Module Definition Unit Test for Service Constraints MUST DO Use @Injectable() and constructor injection for all services — never instantiate services with new Validate all inputs with class validator decorators on DTOs and enable ValidationPipe globally Use DTOs for all request/response bodies; never pass raw req.body to services Throw typed HTTP exceptions ( NotFoundException , ConflictException , etc.) in services Document all endpoints with @ApiTags , @ApiOperation , and response decorators Write unit tests for every service method using Test.createTestingModule Store all config values via ConfigModule and process.env ; never hardcode them MUST NOT DO Expose passwords, secrets, or internal stack traces in responses Accept unvalidated user input — always apply ValidationPipe Use any type unless absolutely necessary and documented Create circular dependencies between modules — use forwardRef() only as a last resort Hardcode hostnames, ports, or credentials in source files Skip error handling in service methods Output Templates When implementing a NestJS feature, provide in this order: 1. Module definition ( .module.ts ) 2. Controller with Swagger decorators ( .controller.ts ) 3. Service with typed error handling ( .service.ts ) 4. DTOs with class validator decorators ( dto/ .dto.ts ) 5. Unit tests for service methods ( .service.spec.ts ) Knowledge Reference NestJS, TypeScript, TypeORM, Prisma, Passport, JWT, class validator, class transformer, Swagger/OpenAPI, Jest, Supertest, Guards, Interceptors, Pipes, Filters [Documentation](https://jeffallan.github.io/claude skills/skills/backend/nestjs expert/)

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