Ah, right, @oscarbenjamin I remember that the cibuildwheel Emscripten installation happens a little later in the process and not at the time of before-all. I think we are good for you to release with #401 as such, but I should explore if there is a chance we can install Emscripten in cibuildwheel at an earlier stage.

However, there is still one way which we could take because we only build for one Pyodide version/ABI (314.0.0, hence the 2026 ABI), which would be that we move the WASM compilation of the libs to before-build, instead of before-all, as that occurs after Emscripten is installed. But before I do that, I think I should ask whether you plan to support only one ABI at a time? The 2027 ABI will arrive next year, and packaging tools will be updated accordingly, but I know other packages are being built for both the 2025 and 2026 ABIs to push to PyPI.

But before I do that, I think I should ask whether you plan to support only one ABI at a time?

Exactly. I don't know what the plan would be in future but I imagine there would be reasons to support at least two pyodide versions simultaneously. Then for the build it is better if before-all builds the libs once to be reused in both wheels if possible.

I imagine there would be reasons to support at least two pyodide versions simultaneously.

That being said I would definitely be happy to go with the lowest maintenance option right now and not consider anything else until the need arises in future. Currently we support zero pyodide versions so we can start by supporting one and then see where that lands us in future.