Don't mind this PR (yet), I am just experimenting with static type checking

For Packit we have it in the pre-commit hooks (along with ruff), you can run it on GitHub via pre-commit.ci or GH Action

Have you considered enabling mypy in vcs diff lint?

I want to also test ruff which is gaining popularity recently. I want to borrow a configuration from opensuse-distro-aliases
https://github.com/rpm-software-management/opensuse-distro-aliases/blob/main/.github/workflows/ci.yml
They seem to be running the check only on some diff as well (poetry run ruff format --check --diff .)

Analysing diffs is never that interesting or powerful because it has a limited scope (the diff); what csdiff does OTOH is that it does the analysis of both old and new base codes, and only prints new issues.

But ruff sounds very good!