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
 
       - 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

@@ -16,7 +16,9 @@ jobs:
           - 'cp311'
           - 'cp312'
           - 'cp313'
+          - 'cp313t'
           - 'cp314'
+          - 'cp314t'
         arch:
           - 'aarch64'
           - 'i686'
@@ -61,9 +63,13 @@ jobs:
             image: 'manylinux_2_28'
           - py: 'cp314'
             image: 'manylinux2014'
+          - py: 'cp314t'
+            image: 'manylinux2014'
           # Drop support for musllinux_1_1 on 3.14+
           - py: 'cp314'
             image: 'musllinux_1_1'
+          - py: 'cp314t'
+            image: 'musllinux_1_1'
     runs-on: ${{ matrix.arch == 'aarch64' && 'ubuntu-22.04-arm' || 'ubuntu-22.04' }}
     env:
       CIBW_ARCHS: ${{ matrix.arch }}
@@ -100,6 +106,7 @@ jobs:
           uvx -p 3.13 [email protected]
 
       - name: Upload Wheel
+        if: ${{ !endsWith(matrix.py, 't') }}
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: linux-${{ matrix.py }}-${{ matrix.arch }}-${{ matrix.abi }}-${{ matrix.image }}
@@ -115,7 +122,9 @@ jobs:
           - 'cp311'
           - 'cp312'
           - 'cp313'
+          - 'cp313t'
           - 'cp314'
+          - 'cp314t'
         arch:
           - 'arm64'
           - 'x86_64'
@@ -139,6 +148,7 @@ jobs:
           uvx -p 3.13 [email protected]
 
       - name: Upload Wheel
+        if: ${{ !endsWith(matrix.py, 't') }}
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: macos-${{ matrix.py }}-${{ matrix.arch }}
@@ -154,7 +164,9 @@ jobs:
           - 'cp311'
           - 'cp312'
           - 'cp313'
+          - 'cp313t'
           - 'cp314'
+          - 'cp314t'
         arch:
           - 'win32'
           - 'win_amd64'
@@ -184,6 +196,7 @@ jobs:
           uvx -p 3.13 [email protected]
 
       - 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

@@ -46,6 +46,8 @@ Version History
 * The cffi backend is now automatically disabled for free-threaded builds
   on Python <3.14, as cffi didn't implement free-threaded 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

@@ -61,7 +61,7 @@ line-length = 80
 select = ["E4", "E7", "E9", "F", "I"]
 
 [tool.cibuildwheel]
-enable = ["cpython-prerelease"]
+enable = ["cpython-freethreading", "cpython-prerelease"]
 build-frontend = "build[uv]"
 
 # Turn compiler warnings into errors.