Sunbytes Nest.js

When to apply

Trigger on Nest.js projects (@nestjs/* imports, nest-cli.json, *.module.ts files, decorators like @Controller, @Injectable, @Module). Always load sb-typescript alongside.

Module organisation

• One module per bounded context (UsersModule, BillingModule, NotificationsModule), not per technical layer (ServicesModule, ControllersModule — never).
• Module file co-located with its controller, services, and DTOs. Folder = module.
• The module's public API is what the module file exports. Nothing else should be imported across module boundaries — enforce with ESLint no-restricted-imports if needed.
• Cross-module communication via injected interfaces or events, not direct service-to-service imports across contexts.

Dependency injection

• Constructor injection only. No property injection (@Inject() on fields).
• Class providers by default. useFactory only when construction needs runtime config.
• @Injectable({ scope: Scope.DEFAULT }) (singleton) — avoid Scope.REQUEST unless you've measured a real need. It disables caching and tanks throughput.
• Depend on interfaces (abstract classes), not concrete services, for things that cross context boundaries (repositories, external clients). Bind the interface to the implementation in the module's providers.