One repository, one module per directory:

• pyproject/ — the shared library. It never gets @check functions.
• ruff/, pytest/, uv/, mypy/, ty/ — tool modules, each with its own checks. ruff/ never runs through uv; it is a standalone binary. Each one's projects is a Dagger collection keyed by project root: checks live on the item type, and the collection's batch functions run them over a selection.
• .dagger/modules/e2e — one end-to-end suite covering every module.
• testdata/ — fixture projects shared by the suite. Several fail on purpose.

The design this implements is hack/designs/python-modules-design.html.

To run the tests: dagger check -m .dagger/modules/e2e. Collections need engine v1.0.0-beta.15 or later; until it is released, use a dev engine.

When changing a module, always make sure the tests are up to date.