Make all four backends safe under free-threaded CPython

.gitattributes

@@ -1,2 +1,3 @@
 benchmark/*.png filter=lfs diff=lfs merge=lfs -text
-benchmark/results/bench_all.csv.gz filter=lfs diff=lfs merge=lfs -text
+benchmark/results/*.png filter=lfs diff=lfs merge=lfs -text
+benchmark/results/*.csv.gz filter=lfs diff=lfs merge=lfs -text

.github/workflows/ci.yml

@@ -44,6 +44,17 @@ jobs:
             os: ubuntu-latest
           - python: "3.14"
             os: ubuntu-latest
+          # Fresh build under a free-threaded interpreter. None of the C
+          # extensions declare Py_mod_gil yet, so importing one re-enables
+          # the GIL by default - PYTHON_GIL=0 below keeps it off anyway so
+          # the suite actually exercises real no-GIL concurrency (their
+          # thread-safety is what tests/test_free_threading.py checks).
+          - python: "3.13t"
+            os: ubuntu-latest
+            free_threaded: true
+          - python: "3.14t"
+            os: ubuntu-latest
+            free_threaded: true
           - python: "3.10"
             os: windows-latest
           - python: "3.11"
@@ -75,12 +86,41 @@ jobs:
           COVERALLS_PARALLEL: 'true'
           COVERALLS_SERVICE_NAME: github
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PYTHON_GIL: ${{ matrix.free_threaded && '0' || '' }}
       - name: Report coverage
         run: uv run coveralls
         continue-on-error: true
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
+  # Builds normally under a regular interpreter, then runs the suite through
+  # a free-threaded one of the same X.Y against that same install. The
+  # compiled extensions' SOABI won't match the free-threaded interpreter, so
+  # they simply fail to import (same ImportError path as any unsupported
+  # platform) - only python_aio ends up available, and unlike the `tests`
+  # matrix's own free-threaded entries above, nothing gets the chance to
+  # re-enable the GIL first.
+  free-threaded-python-only:
+    needs: lint
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python: ["3.13", "3.14"]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: astral-sh/setup-uv@v5
+        with:
+          python-version: "${{ matrix.python }}"
+      - run: uv sync --extra develop
+      - run: uv python install "${{ matrix.python }}t"
+      - name: Run tests under the free-threaded interpreter against this install
+        run: |
+          FREE_THREADED_PYTHON="$(uv python find "${{ matrix.python }}t")"
+          PYTHONPATH="$(pwd)/.venv/lib/python${{ matrix.python }}/site-packages" "$FREE_THREADED_PYTHON" -m pytest -sv tests
+        env:
+          FORCE_COLOR: 1
+
   finish:
     needs:
       - tests

.github/workflows/publish.yml

@@ -35,7 +35,7 @@ jobs:
       contents: write
     strategy:
       matrix:
-        python: [cp310-cp310, cp311-cp311, cp312-cp312, cp313-cp313, cp314-cp314]
+        python: [cp310-cp310, cp311-cp311, cp312-cp312, cp313-cp313, cp314-cp314, cp313-cp313t, cp314-cp314t]
     steps:
       - uses: actions/checkout@v4
       - name: Set version from release tag
@@ -61,7 +61,7 @@ jobs:
       contents: write
     strategy:
       matrix:
-        python: [cp310-cp310, cp311-cp311, cp312-cp312, cp313-cp313, cp314-cp314]
+        python: [cp310-cp310, cp311-cp311, cp312-cp312, cp313-cp313, cp314-cp314, cp313-cp313t, cp314-cp314t]
     steps:
       - uses: actions/checkout@v4
       - name: Set version from release tag
@@ -87,7 +87,7 @@ jobs:
       contents: write
     strategy:
       matrix:
-        python: [cp310-cp310, cp311-cp311, cp312-cp312, cp313-cp313, cp314-cp314]
+        python: [cp310-cp310, cp311-cp311, cp312-cp312, cp313-cp313, cp314-cp314, cp313-cp313t, cp314-cp314t]
     steps:
       - uses: actions/checkout@v4
       - name: Set version from release tag
@@ -124,7 +124,7 @@ jobs:
       contents: write
     strategy:
       matrix:
-        python: [cp310-cp310, cp311-cp311, cp312-cp312, cp313-cp313, cp314-cp314]
+        python: [cp310-cp310, cp311-cp311, cp312-cp312, cp313-cp313, cp314-cp314, cp313-cp313t, cp314-cp314t]
     steps:
       - uses: actions/checkout@v4
       - uses: astral-sh/setup-uv@v5
@@ -154,17 +154,15 @@ jobs:
       contents: write
     strategy:
       matrix:
-        python: ["3.10", "3.11", "3.12", "3.13", "3.14"]
+        python: ["3.10", "3.11", "3.12", "3.13", "3.14", "3.13t", "3.14t"]
     steps:
       - uses: actions/checkout@v4
       - uses: astral-sh/setup-uv@v5
-      - name: Set version from release tag
-        run: uv version --frozen "${GITHUB_REF_NAME#v}"
-      - uses: actions/setup-python@v5
         with:
           python-version: "${{ matrix.python }}"
-      - run: pip install build
-      - run: python -m build --wheel
+      - name: Set version from release tag
+        run: uv version --frozen "${GITHUB_REF_NAME#v}"
+      - run: uv build --wheel
       - uses: actions/upload-artifact@v4
         with:
           name: wheel-macos-${{ matrix.python }}

Makefile

@@ -28,12 +28,22 @@ sdist:
 	python3.14 -m venv $@
 	$@/bin/python -m pip install -U pip setuptools build wheel
 
-mac_wheel: .venvs/3.10 .venvs/3.11 .venvs/3.12 .venvs/3.13 .venvs/3.14
+.venvs/3.13t: .venvs
+	python3.13t -m venv $@
+	$@/bin/python -m pip install -U pip setuptools build wheel
+
+.venvs/3.14t: .venvs
+	python3.14t -m venv $@
+	$@/bin/python -m pip install -U pip setuptools build wheel
+
+mac_wheel: .venvs/3.10 .venvs/3.11 .venvs/3.12 .venvs/3.13 .venvs/3.14 .venvs/3.13t .venvs/3.14t
 	.venvs/3.10/bin/python -m build
 	.venvs/3.11/bin/python -m build
 	.venvs/3.12/bin/python -m build
 	.venvs/3.13/bin/python -m build
 	.venvs/3.14/bin/python -m build
+	.venvs/3.13t/bin/python -m build
+	.venvs/3.14t/bin/python -m build
 
 linux_wheel:
 	docker run -it --rm \