feat: pyemscripten platform tag (PEP 783), 314.0a1, pyodide-eol flag, and maintenance updates (#2812)

* Use `pyodide config get emscripten_dir`

* Update constraints

* Updates for `pyemscripten` platform tag

* Weird constraints stuff...

* Revert "Weird constraints stuff..."

This reverts commit 4bd785de872269c0b27362ee800f17288b2b4789.

* Add some special constraints for pyodide

* Wheel pyemscripten collision

* Put delocate back in constraints (not needed tho)

* Drop Pyodide 0.27.7 (cp312-pyodide_wasm32)

* Add Pyodide 314.0.0a1 (cp314-pyodide_wasm32)

* Delete no-longer-needed Pyodide 312 constraints

* Update Pyodide 313 and 314 constraints

* Add back prerelease stuff and update tests

* Fix `test_pyodide_on_windows`

* Update and fix tests some more

* Also enable pyodide-prerelease in GHA sample build

* Update tests yet again (`SINGLE_PYTHON_VERSION` changes)

* Add a Pyodide-specific maintenance guide

* Add suggestions from Hood and Gyeongjae

Co-Authored-By: Hood Chatham <roberthoodchatham@gmail.com>
Co-Authored-By: Gyeongjae Choi <def6488@gmail.com>

* Add "Last updated: May 2026" to Pyodide document

* Add a Pyodide EOL filter

* Fix typo

* Update maintenance docs about EoL Pyodide

* Add Pyodide 312 constraints back

* Update Pyodide 313 and 314 constraints

* Remove "experimental" note about Pyodide

* Remove another experimental Pyodide sentence

* Add docs about the `pyodide-eol` enable option

---------

Co-authored-by: Hood Chatham <roberthoodchatham@gmail.com>
Co-authored-by: Gyeongjae Choi <def6488@gmail.com>
Co-authored-by: Henry Schreiner <henryfs@princeton.edu>

unit_test/build_selector_test.py

@@ -97,8 +97,8 @@ def test_build_filter_pyodide_prerelease() -> None:
         skip_config="",
         enable=frozenset([EnableGroup.PyodidePrerelease]),
     )
-    assert build_selector("cp312-pyodide_wasm32")
     assert build_selector("cp313-pyodide_wasm32")
+    assert build_selector("cp314-pyodide_wasm32")
 
 
 def test_build_filter_pyodide() -> None:
@@ -107,8 +107,20 @@ def test_build_filter_pyodide() -> None:
         skip_config="",
         enable=frozenset(),
     )
+    assert build_selector("cp313-pyodide_wasm32")
+    assert not build_selector("cp312-pyodide_wasm32")
+    assert not build_selector("cp314-pyodide_wasm32")
+
+
+def test_build_filter_pyodide_eol() -> None:
+    build_selector = BuildSelector(
+        build_config="*",
+        skip_config="",
+        enable=frozenset([EnableGroup.PyodideEoL]),
+    )
     assert build_selector("cp312-pyodide_wasm32")
     assert build_selector("cp313-pyodide_wasm32")
+    assert not build_selector("cp314-pyodide_wasm32")
 
 
 def test_skip() -> None:

unit_test/main_tests/main_platform_test.py

@@ -308,7 +308,7 @@ def test_pyodide_on_windows(
     monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]
 ) -> None:
     monkeypatch.setattr(sys, "platform", "win32")
-    monkeypatch.setattr(sys, "argv", [*sys.argv, "--only", "cp312-pyodide_wasm32"])
+    monkeypatch.setattr(sys, "argv", [*sys.argv, "--only", "cp314-pyodide_wasm32"])
 
     with pytest.raises(SystemExit) as exit:
         main()

unit_test/options_test.py

@@ -35,7 +35,7 @@ manylinux-x86_64-image = "manylinux_2_28"
 
 environment-pass = ["EXAMPLE_ENV"]
 
-pyodide-version = "0.28.0"
+pyodide-version = "0.29.4"
 
 [tool.cibuildwheel.macos]
 test-requires = "else"
@@ -92,7 +92,7 @@ def test_options_1(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
     assert local.manylinux_images["x86_64"] == pinned_x86_64_container_image["manylinux_2_34"]
 
     local = options.build_options("cp312-pyodide_wasm32")
-    assert local.pyodide_version == "0.28.0"
+    assert local.pyodide_version == "0.29.4"
 
 
 def test_passthrough(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None: