Modern API Architecture and Project Structure

Organize a FastAPI project into a scalable folder structure with routers, schemas, models, and configuration.

Manage environment variables and application settings using Pydantic's `BaseSettings`.

Implement the repository pattern to decouple database logic from business logic.

Implement a service layer to encapsulate business logic, orchestrating calls between route handlers and repositories.

Implement API versioning by prefixing routers.