build: PyPI release workflow with abi3 wheels for 5 platforms

.github/workflows/release.yml

@@ -0,0 +1,137 @@
+name: Release
+
+# Builds abi3 wheels (one per platform, any Python >= 3.9) and an sdist, tests each
+# wheel, and publishes to PyPI when a version tag is pushed.
+#
+# - pull requests touching packaging: build + test only, nothing is published
+# - workflow_dispatch: same, on demand
+# - tag vX.Y.Z (must match the version in Cargo.toml): build, test, publish
+
+on:
+  push:
+    tags: ["v*"]
+  pull_request:
+    paths:
+      - .github/workflows/release.yml
+      - pyproject.toml
+      - Cargo.toml
+      - Cargo.lock
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  wheels:
+    name: wheel ${{ matrix.platform.name }}
+    runs-on: ${{ matrix.platform.runner }}
+    strategy:
+      fail-fast: false
+      matrix:
+        platform:
+          - { name: linux-x86_64, runner: ubuntu-latest, target: x86_64, manylinux: "2_28", test: true }
+          - { name: linux-aarch64, runner: ubuntu-24.04-arm, target: aarch64, manylinux: "2_28", test: true }
+          - { name: macos-arm64, runner: macos-14, target: aarch64-apple-darwin, test: true }
+          # cross-compiled on the arm64 runner, so it can't be run here
+          - { name: macos-x86_64, runner: macos-14, target: x86_64-apple-darwin, test: false }
+          - { name: windows-x86_64, runner: windows-latest, target: x64, test: true }
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Build wheel
+        uses: PyO3/maturin-action@v1
+        with:
+          target: ${{ matrix.platform.target }}
+          manylinux: ${{ matrix.platform.manylinux || 'auto' }}
+          args: --release --locked --out dist
+
+      # the abi3 wheel is tested on the oldest and newest supported Pythons
+      - uses: actions/setup-python@v5
+        id: py-oldest
+        if: matrix.platform.test
+        with:
+          python-version: "3.9"
+
+      - uses: actions/setup-python@v5
+        id: py-newest
+        if: matrix.platform.test
+        with:
+          python-version: "3.13"
+
+      # runs from outside the repo so the installed wheel is imported, not the source tree
+      - name: Test wheel
+        if: matrix.platform.test
+        shell: bash
+        env:
+          PYTHONS: ${{ steps.py-oldest.outputs.python-path }};${{ steps.py-newest.outputs.python-path }}
+        run: |
+          IFS=';' read -ra pythons <<< "$PYTHONS"
+          for py in "${pythons[@]}"; do
+            echo "::group::$py"
+            venv="$RUNNER_TEMP/venv-$("$py" -c 'import sys; print("%d%d" % sys.version_info[:2])')"
+            "$py" -m venv "$venv"
+            bin="$venv/bin"; [ "$RUNNER_OS" = "Windows" ] && bin="$venv/Scripts"
+            "$bin/python" -m pip install -q dist/*.whl onnx onnxruntime
+            cd "$RUNNER_TEMP"
+            "$bin/python" -c "import sys, burn_python as b; print(sys.version, b.__version__, b.available_backends())"
+            "$bin/python" "$GITHUB_WORKSPACE/tests/test_ops.py"
+            cd "$GITHUB_WORKSPACE"
+            echo "::endgroup::"
+          done
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: wheel-${{ matrix.platform.name }}
+          path: dist/*.whl
+
+  sdist:
+    name: sdist
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Build sdist
+        uses: PyO3/maturin-action@v1
+        with:
+          command: sdist
+          args: --out dist
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: sdist
+          path: dist/*.tar.gz
+
+  publish:
+    name: publish to PyPI
+    if: startsWith(github.ref, 'refs/tags/v')
+    needs: [wheels, sdist]
+    runs-on: ubuntu-latest
+    # PyPI trusted publishing: no API token, PyPI trusts this workflow + environment
+    environment:
+      name: pypi
+      url: https://pypi.org/p/burn-python
+    permissions:
+      id-token: write
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Check tag matches Cargo.toml version
+        run: |
+          version=$(grep -m1 '^version' Cargo.toml | cut -d'"' -f2)
+          if [ "v$version" != "$GITHUB_REF_NAME" ]; then
+            echo "::error::tag $GITHUB_REF_NAME does not match Cargo.toml version $version"
+            exit 1
+          fi
+
+      - uses: actions/download-artifact@v4
+        with:
+          path: dist
+          merge-multiple: true
+
+      - run: ls -la dist
+
+      - uses: pypa/gh-action-pypi-publish@release/v1

.gitignore

@@ -5,7 +5,6 @@ dist/
 *.egg-info/
 __pycache__/
 .venv/
-Cargo.lock
 .claude/
 tests/*.onnx
 tests/*.npy

CHANGELOG.md

@@ -8,6 +8,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ### Added
+- PyPI packaging: `.github/workflows/release.yml` builds abi3 wheels (one per platform,
+  Python ≥ 3.9) for Linux x86_64/aarch64, macOS arm64/x86_64 and Windows x86_64, tests
+  them on Python 3.9 and 3.13, and publishes to PyPI via trusted publishing on a `vX.Y.Z` tag.
 - GPU inference: `load_onnx(path, backend="wgpu")`, compiled to Metal on macOS and
   Vulkan on Linux / Windows. ResNet-18 on an Apple M-series GPU: 6.1 ms at batch 1,
   35.6 ms at batch 8 (~3x faster than ONNX Runtime on CPU). `available_backends()`
@@ -30,6 +33,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Initial maturin/pyo3 project scaffold, `burn-flex` + `onnx-ir` dependencies.
 
 ### Changed
+- License files now match the declared license: dual MIT / Apache-2.0
+  (`LICENSE-MIT`, `LICENSE-APACHE`), replacing a GPL-3.0 `LICENSE` file that contradicted it.
+- `Cargo.lock` is committed and release builds use `--locked`.
+- Package version comes from `Cargo.toml` only.
 - All ops now run on burn-dispatch's `Dispatch` backend; the device is chosen per model.
   The unused `burn` umbrella dependency was replaced by `burn-dispatch`.
 - Backend failures that happen on a worker thread (e.g. no GPU adapter) now report the