10-backend-fastapi

Backend stack:

• FastAPI
• Pydantic
• SQLAlchemy or SQLModel
• PostgreSQL
• Redis for cache/queue support

Backend rules:

• Use clean architecture.
• Routes/controllers should only handle HTTP concerns.
• Business logic must live in services.
• Database access must live in repositories.
• Validation must be done using schemas/models.
• Use dependency injection patterns where appropriate.
• Use async I/O where supported and beneficial.
• Use pagination for list endpoints.
• Use consistent response models.
• Use centralized exception handling.

API conventions:

• Follow RESTful naming.
• Version APIs when needed, e.g. /api/v1/.
• Use proper status codes.
• Return predictable response structure.
• Do not leak internal stack traces or raw database errors.

Preferred backend structure:

• backend/api/routes/
• backend/api/dependencies/
• backend/services/
• backend/repositories/
• backend/models/
• backend/schemas/
• backend/core/
• backend/utils/
• backend/tests/

Coding expectations:

• Add type hints to functions.
• Add docstrings for non-trivial service methods.
• Keep routes thin and declarative.
• Keep service methods focused and testable.
• Reuse existing utilities before creating new ones.

Do not:

• Put SQL or ORM-heavy logic inside route files.
• Put business logic inside Pydantic schemas.
• Put environment variables directly across many files; centralize in config.
• Mix unrelated domains in the same service file.