python-backend Production-ready Python backend patterns for FastAPI, SQLAlchemy, and Upstash. When to Use This Skill - Building REST APIs with FastAPI - Implementing JWT/OAuth2 authentication - Setting up SQLAlchemy async databases - Integrating Redis/Upstash caching and rate limiting - Refactoring AI-generated Python code - Designing API patterns and project structure Core Principles 1. Async-first - Use async/await for I/O operations 2. Type everything - Pydantic models for validation 3. Dependency injection - Use FastAPI's Depends() 4. Fail fast - Validate early, use HTTPException 5. Secur…