fix(wheels): produce a platform wheel (py3-none-<plat>), not pure-Python

cibuildwheel rejected the build because setup.py's build_py bundles a prebuilt
loadable but didn't mark the distribution impure, so setuptools tagged the wheel
py3-none-any. Override bdist_wheel to set root_is_pure=False and tag it
py3-none-<platform> (the loadable is not a CPython extension, so it is
ABI-agnostic but platform-specific). Limit cibuildwheel to one CPython build per
platform, since every version now yields the same py3-none wheel. Verified
locally: the wheel builds as py3-none-macosx_14_0_arm64.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: mstrathman

.github/workflows/wheels.yml

@@ -32,9 +32,10 @@ jobs:
         with:
           package-dir: bindings/python
         env:
-          # skip pypy and musl for the first cut; CPython manylinux + macOS cover
-          # the target audience
-          CIBW_SKIP: "pp* *-musllinux*"
+          # the loadable is ABI-agnostic, so one CPython build per platform gives
+          # one py3-none-<platform> wheel usable by any Python there. Skip musl.
+          CIBW_BUILD: "cp312-*"
+          CIBW_SKIP: "*-musllinux*"
           CIBW_BUILD_VERBOSITY: "1"
       - uses: actions/upload-artifact@v4
         with:

bindings/python/setup.py

@@ -8,6 +8,11 @@
 from setuptools import setup
 from setuptools.command.build_py import build_py
 
+try:  # setuptools >= 70.1 vendors bdist_wheel; older builds use the wheel package
+    from setuptools.command.bdist_wheel import bdist_wheel as _bdist_wheel
+except ImportError:
+    from wheel.bdist_wheel import bdist_wheel as _bdist_wheel
+
 HERE = os.path.dirname(os.path.abspath(__file__))
 EXT = {"darwin": "dylib", "win32": "dll"}.get(sys.platform, "so")
 
@@ -28,4 +33,19 @@ def run(self):
         super().run()
 
 
-setup(cmdclass={"build_py": Build})
+class BDistWheel(_bdist_wheel):
+    """The wheel ships a prebuilt loadable, so it is platform-specific but not
+    tied to the CPython ABI. Tag it py3-none-<platform> rather than the default
+    py3-none-any (which would claim the wheel is pure Python and makes
+    cibuildwheel reject it)."""
+
+    def finalize_options(self):
+        super().finalize_options()
+        self.root_is_pure = False
+
+    def get_tag(self):
+        _python, _abi, plat = super().get_tag()
+        return "py3", "none", plat
+
+
+setup(cmdclass={"build_py": Build, "bdist_wheel": BDistWheel})