Python

A comprehensive set of Python development standards that Claude will follow when writing or reviewing your code. It covers the practical stuff like preferring composition over inheritance, using Protocol classes for interfaces, and keeping one service per module. The guidelines push for modern Python patterns (union types over Optional, built-in generics over typing module), Pydantic v2 for data models, and pytest for testing with the AAA pattern. It also includes opinionated but sensible rules like requiring dependency injection, organizing environment variables in a single file, and mirroring your src structure in tests. Useful if you want consistency across a codebase without explaining your conventions every time.