python-fastapi

## Quick Reference

| Layer | File | Purpose |
|-------|------|---------|
| Entrypoint | `main.py` | App factory, lifespan |
| Config | `config.py` | pydantic-settings |
| Routes | `api/v1/endpoints/` | Endpoint handlers |
| Schemas | `schemas/` | Pydantic models |
| Models | `models/` | SQLAlchemy models |
| Services | `services/` | Business logic |
| Deps | `api/deps.py` | Dependency injection |

| Pydantic Pattern | Use Case |
|------------------|----------|
| `UserCreate` | Input for creation |
| `UserUpdate` | Input for updates |
| `UserResponse` | API output |
| `UserInDB` | Internal with hash |

| Dependency | Code |
|------------|------|
| DB session | `db: Annotated[AsyncSession, Depends(get_db)]` |
| Current user | `user: Annotated[User, Depends(get_current_user)]` |
| Type alias | `CurrentUser = Annotated[User, Depends(...)]` |

| Production | Config |
|------------|--------|
| Server | `gunicorn -w 4 -k uvicorn.workers.UvicornWorker` |
| Workers | `CPU cores` for async |

## When to Use This Skill

Use for **FastAPI development**:
- Setting up FastAPI project structure
- Creating Pydantic schemas with validation
- Implementing dependency injection
- JWT authentication setup
- Docker deployment configuration

**Related skills:**
- For async patterns: see `python-asyncio`
- For testing: see `python-testing`
- For type hints: see `python-type-hints`

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# FastAPI Production Best Practices (2025)

## Overview

FastAPI is a modern, high-performance web framework for building APIs. Built on Starlette and Pydantic, it provides automatic validation, serialization, and OpenAPI documentation.

## Project Structure

### Scalable Structure (Recommended)

```
src/
├── app/
│   ├── __init__.py
│   ├── main.py              # Application factory
│   ├── config.py            # Settings management
│   ├── database.py          # Database setup
│   ├── dependencies.py      # Shared dependencies
│   ├── api/
│   │   ├── __init__.py
│   │   ├── v1/
│   │   │   ├── __init__.