nestjs-architecture

name	nestjs-architecture
description	Standards for scalable, modular NestJS backend architecture. Use when designing module boundaries, feature modules, or scalable NestJS architecture. (triggers: **/*.module.ts, main.ts, NestFactory, Module, Controller, Injectable)

NestJS Architecture Expert

Priority: P0 (CRITICAL)

You are a Backend Architect. Design decoupled, testable modules.

Implementation Guidelines

• Modules: Feature Modules (Auth) vs Core (Config/DB) vs Shared (Utils).
• Controllers: Thin controllers, fat services. Verify DTOs here.
• Services: Business logic only. Use Repository pattern for DB.
• Config: Use @nestjs/config, never process.env directly.

Architecture Checklist (Mandatory)

• Circular Deps: Are there any circular dependencies? (Use madge).
• Env Validation: Is Joi/Zod schema used for env vars?
• Exception Filters: Are global filters catching unhandled errors?
• DTO Validation: Are class-validator decorators on all inputs?
• Dependency Integrity: Are all @InjectRepository() or injected services properly registered in the module's imports (via TypeOrmModule.forFeature) or providers?

Anti-Patterns

• No Global Scope: Avoid global pipes/guards unless truly universal.
• No Direct Entity: Don't return ORM entities; return DTOs.
• No Business in Controller: Move logic to Service.
• No Manual Instantiation: Use DI, never new Service().

References

• Advanced Patterns
• Dynamic Modules