Three-Layer Architecture

You can structure a TypeScript codebase for maintainability by applying a three-layer architecture that separates code into server, service, and repository layers to ensure clear separation of concerns and scalable data access.

The server-service-repository pattern is a layered architecture structure where server.ts handles auth and validation, service.ts contains business logic, and repository.ts performs database operations to isolate concerns and improve testability.

To organize a new feature, place your code into app/features/<feature>/ with distinct server.ts, service.ts, and repository.ts files, then wire up your routes and tests to establish clear data access and business logic boundaries.

You should use a layered architecture for web apps requiring clear separation of concerns, testability, and scalable data access, allowing you to evolve the server, service, and repository layers independently as requirements grow.

Yes, the server-service-repository pattern works effectively with TypeScript to enforce clean code and maintainability, providing structured separation of concerns across orchestration, business logic, and database operations.