Python CI on GitHub Actions

pip install takes minutes and pytest runs on a single core.

Why it happens

Wheels are resolved and often compiled on every run, and pytest is serial unless you tell it otherwise.

What to change

1. Switch to uv — resolution and install are typically 10–30× faster than pip
2. Cache the virtualenv keyed on the lockfile, not just the pip HTTP cache
3. Run pytest -n auto with pytest-xdist to use every core on the runner
4. Split slow integration tests into their own job so unit feedback stays fast

Python on runnerhut

jobs:
  test:
    runs-on: runnerhut-8vcpu-ubuntu-2404
    steps:
      - uses: actions/checkout@v4
      - uses: astral-sh/setup-uv@v5
        with: { enable-cache: true }
      - run: uv sync --frozen
      - run: uv run pytest -n auto --dist loadgroup

The only runnerhut-specific line is `runs-on: runnerhut-8vcpu-ubuntu-2404`. Everything else is standard GitHub Actions — the same actions, the same secrets and the same permissions model you use today.