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name: python-code description: Python coding conventions, tooling, and style guide. Auto-loads when writing or reviewing Python code.

Python Conventions

Follow these conventions when working on Python code.

Tooling

Use uv for everything. Do not use pip/venv/poetry directly.

Style

• Write Pythonic code; choose the simplest construct that expresses intent
• Functional for stateless transforms; dataclasses for cohesive state/config
• Use Pydantic (or TypedDict + validators) for validating external data
• Prefer composition over inheritance; keep class hierarchies shallow
• Apply DRY and YAGNI before adding a class
• Use lower_snake_case for files/dirs (e.g., routers/user_routes.py)

Testing

• Mirror source layout under tests/
• Keep fixtures minimal; prefer factory helpers over deep fixture chains
• Run before handoff: uv run ruff check && uv run ty check && uv run pytest

Dependencies

• Minimize new deps; justify every addition
• Prefer stdlib first, then existing project deps
• Use uv add/uv remove to manage deps—don't edit pyproject.toml by hand
• Remove dead deps when noticed