python

Typed, tested, packaged Python — modules and functions first, classes where state earns them.

Activate when

• Writing, reviewing, or testing Python; packaging, typing, async, or tooling decisions.

Do NOT activate for

• FastAPI specifics (see frameworks/fastapi); ML serving (see ml/model-serving).

Procedure

1. Version: detect interpreter + dependency pins (pyproject/uv.lock/requirements); research behavior in https://docs.python.org/ for that version.
2. Types everywhere public; mypy/pyright clean; Pydantic v2 at boundaries (see frameworks/fastapi).
3. Async for I/O-bound with anyio/asyncio discipline; sync for CPU-bound; no blocking calls inside async paths.
4. Structure: src/ layout, protocols/composition over deep hierarchies; module placement per architecture/language-modularity.
5. Quality: Ruff lint+format, pytest with fixtures/factories, coverage as signal not target.
6. Verify: typecheck + lint + tests green on the pinned interpreter; packaging installs clean (pip install . in fresh venv or uv equivalent).

References

• Registry: ../../research/documentation-search/references/framework-registry.yaml (python, uv, ruff, pytest, pydantic).