Backend Development Skill

Build production-grade FastAPI features using established patterns. SQLModel for persistence, Pydantic DTOs for layer boundaries, Result for error handling.

Core Philosophy

• SQLModel (table=True) for database models with automatic key/timestamps via BaseModel
• DTOs (Pydantic) at every layer boundary — request DTOs in, response DTOs out
• Repositories own the conversion — SQLModel never leaks past the repository
• Result[ErrorType, T] for explicit error handling
• Typed errors from app.core.errors (NotFound, AlreadyExists, Forbidden, etc.)

Assumptions

This skill assumes your project provides these custom utilities (import paths use app as a placeholder for your root package):