Contributing

$ uv sync
$ scripts/check.sh          # every gate CI runs
$ uv run pytest -n auto     # the fast tier (about 10 seconds)
$ uv run pytest -m nightly  # real-library corpus and a 1500-program fuzz campaign
$ scripts/mutation.sh       # mutation testing of the analysis core

Quality gates

Every change must pass all of these:

Gate	Tool
Formatting, and every lint rule (with a short, justified ignore list)	ruff format, ruff check with select = ["ALL"]
Types, checked twice	pyright strict (plus override, cycle and unnecessary-ignore checks), mypy --strict
Tests	pytest with warnings as errors, strict markers and config, random order, timeouts
Branch coverage ≥ 96%	coverage, including CLI subprocesses
Mutation kill rate ≥ 99% (nightly)	mutmut on the effects rules, class analysis and shaker
No dead code	vulture, and a test that shaking shakeout removes nothing
Spelling, pyproject.toml schema	codespell, validate-pyproject
Packaging	uv build, twine check --strict, check-wheel-contents, install smoke test
Supply chain and workflows	pip-audit, zizmor (pedantic), actionlint, SHA-pinned actions
Docs	mkdocs build --strict, plus tests that every CLI flag and config key is documented

Adding a case

Behavior is specified by .case files in tests/cases/: a TOML header with expectations, then === path sections with the program. Run uv run pytest --update-goldens, then review the generated .golden report like code.