ci: add coverage for free-threaded Python

We add 3.13t and 3.14t into the matrix.

For the wheels, we skip upload of free-threaded wheels for the moment
because we don't yet want to officially declare free-threaded support.

Closes #276.

Author: clin1234

.github/workflows/test.yml

@@ -22,7 +22,9 @@ jobs:
           - '3.11'
           - '3.12'
           - '3.13'
+          - '3.13t'
           - '3.14'
+          - '3.14t'
         arch:
           - 'arm64'
           - 'x86'
@@ -99,6 +101,7 @@ jobs:
           uv -v run --locked pytest --numprocesses=auto --hypothesis-profile=${HYPOTHESIS_PROFILE} -v tests/
 
       - name: Test CFFI Backend
+        if: matrix.py != '3.13t'
         env:
           PYTHON_ZSTANDARD_IMPORT_POLICY: 'cffi'
         run: |

.github/workflows/typing.yml

@@ -15,7 +15,9 @@ jobs:
           - '3.11'
           - '3.12'
           - '3.13'
+          - '3.13t'
           - '3.14'
+          - '3.14t'
     runs-on: 'ubuntu-24.04'
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0

.github/workflows/wheel.yml

@@ -29,7 +29,9 @@ jobs:
           - 'cp311-cp311'
           - 'cp312-cp312'
           - 'cp313-cp313'
+          - 'cp313-cp313t'
           - 'cp314-cp314'
+          - 'cp314-cp314t'
         exclude:
           - image: 'musllinux_1_1_aarch64'
             py: 'cp314-cp314'
@@ -50,6 +52,7 @@ jobs:
           docker run -e PYPATH=/opt/python/${{ matrix.py }} -e ZSTD_WARNINGS_AS_ERRORS=1 --rm -v `pwd`:/project quay.io/pypa/${{ matrix.image }} /project/ci/build-manylinux-wheel.sh
 
       - name: Upload Wheel
+        if: ${{ !endsWith(matrix.py, 't') }}
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: linux-${{ matrix.py }}-${{ matrix.image }}
@@ -65,7 +68,9 @@ jobs:
           - 'cp311'
           - 'cp312'
           - 'cp313'
+          - 'cp313t'
           - 'cp314'
+          - 'cp314t'
         arch:
           - 'arm64'
           - 'x86_64'
@@ -75,6 +80,7 @@ jobs:
       CIBW_BUILD: ${{ matrix.py }}-*
       CIBW_BUILD_VERBOSITY: '1'
       ZSTD_WARNINGS_AS_ERRORS: '1'
+
     steps:
       - name: Set up Python
         uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
@@ -94,6 +100,7 @@ jobs:
           cibuildwheel --output-dir dist
 
       - name: Upload Wheel
+        if: ${{ !endsWith(matrix.py, 't') }}
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: macos-${{ matrix.py }}-${{ matrix.arch }}
@@ -109,7 +116,9 @@ jobs:
           - '3.11'
           - '3.12'
           - '3.13'
+          - '3.13t'
           - '3.14'
+          - '3.14t'
         arch:
           - 'x86'
           - 'x64'
@@ -141,6 +150,7 @@ jobs:
           python -m pip wheel -w dist .
 
       - name: Upload Wheel
+        if: ${{ !endsWith(matrix.py, 't') }}
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: windows-${{ matrix.py }}-${{ matrix.arch }}

docs/news.rst

@@ -16,6 +16,8 @@ Version History
   (#274)
 * The cffi backend is now automatically disabled for nogil builds on Python
   <3.14, as cffi didn't implement nogil support until the 2.0 release. (#274)
+* Added CI coverage for free-threaded CPython 3.13 and 3.14. We do not yet
+  formally support free-threaded builds. (#276)
 
 0.24.0 (released 2025-08-17)
 ============================

pyproject.toml

@@ -58,7 +58,7 @@ line-length = 80
 select = ["E4", "E7", "E9", "F", "I"]
 
 [tool.cibuildwheel]
-enable = ["cpython-prerelease"]
+enable = ["cpython-freethreading", "cpython-prerelease"]
 
 # This is needed to suppress generation of license-file, which isn't
 # compatible with metadata version 2.1, which our pinned setuptools