Instruction file imported from EmperorRAG/my-projects-monorepo (.github/instructions/nestjs/nestjs-controllers-services.instructions.md). Copyright stays with the author.

NestJS Controllers & Services

Controllers

• Keep controllers thin: accept requests, trigger validation, and delegate to services for business logic.
• Apply guards, interceptors, and pipes at the route or controller level to keep behavior explicit.
• Return DTOs or domain objects rather than raw database entities when responses need shaping.

Services

• Implement core business logic inside services marked @Injectable() and use constructor injection for dependencies.
• Handle side effects (persistence, messaging, emails) within services and surface meaningful errors for filters to translate.
• Split large services into focused units to keep responsibilities narrow and testable.