backend-dev-guidelines

Enforce layered architecture with clear separation between entry points (tRPC routers, API endpoints), services, and data access via Prisma. This pattern ensures consistent routing, testability, and observability across your Next.js 14 backend.

Apply projectId filtering at the service and database layers to enforce tenant isolation. This prevents cross-tenant data leakage while maintaining a shared schema and consistent query patterns across your monorepo.

Use OpenTelemetry for distributed tracing and the traceException pattern for standardized error handling across tRPC procedures, Express endpoints, and BullMQ processors. This enables consistent observability and debugging across all backend components.

Use Zod v4 for input validation on tRPC routers and API endpoints, and env.mjs for centralized environment configuration. This ensures type safety and consistent validation across your entire backend.

Create queue processors that follow the same layered architecture as synchronous services, apply traceException error handling, and include standard test scaffolds. This maintains consistency between synchronous and asynchronous backend tasks.

Implement standard testing scaffolds that cover services, Prisma queries, and BullMQ processors with isolated test environments. This ensures reliable, maintainable coverage across all backend layers in your monorepo.