The 0.22.0 release run died on cp310-musllinux_riscv64 with Command ['which', 'uv'] failed with code 1, from my riscv64 matrix entry. All six manylinux riscv64 wheels in that same job built, repaired and tested fine, so it is specific to the musllinux image.

pypa/manylinux used to skip installing uv in the musllinux riscv64 image. At the commit the pinned image was built from (8dbfa8e, 4 June), docker/build_scripts/finalize.sh had:

musllinux*_riscv64-uv) continue;;  # uv doesn't provide musl riscv64 wheels due to Rust issues

That was removed by pypa/manylinux#1969 on 11 July, and their image test suite now runs uv venv / uv pip install inside musllinux riscv64. The comment was already out of date when it was written: uv has published a manylinux_2_31_riscv64.musllinux_1_1_riscv64 wheel since 0.11.18 (1 June).

The pins differ across cibuildwheel releases:

So build-frontend = "build[uv]" has nothing to find on 4.1.0. This bumps both uvx --from pins to 4.2.0.

4.2.0 builds CPython 3.15 by default, but .cibuildwheel.toml sets an explicit build = "cp310-* cp311-* cp312-* cp313-* cp314-* cp314t-*" list, so no new target appears. The rest of that release is Pyodide 314.0.4, a GraalPy pip hold, and download retries.

I have not run this. The reasoning is from the failing job log and the manylinux source, not from a green build. CI here will not test it either unless someone adds the build-riscv64 label, since the riscv64 job is excluded on unlabelled PRs, and even then CIBW_SKIP drops musllinux outside a release build. So the honest state is that only a release run proves it. If you would rather not move cibuildwheel right before a release, musllinux-riscv64-image in .cibuildwheel.toml pins just that one image and leaves everything else alone.

Two things worth knowing either way:

The riscv64 job is gated behind the build-riscv64 label on PRs, and CIBW_SKIP drops musllinux unless build-all is set. So nothing had ever exercised musllinux riscv64 until the release turned build-all on. Whatever you decide here, that combination will keep hiding riscv64 musllinux breakage until release day.

Dependabot covers github-actions and uv, but the cibuildwheel version is an inline uvx --from argument rather than a tracked dependency, which is why it sat at 4.1.0. Moving it into the uv ecosystem somehow would stop the next one, though I do not have a clean suggestion for how.

Refs #1134, #987