name: Build CPU Artifacts

# Build LMCache with NO_GPU_EXT=1 (common C++ extensions only).
# Gates the CPU-only build path against regression.

on:
    workflow_call:
    pull_request:
        branches:
            - dev
            - "release-**"
        paths:
            - 'setup.py'
            - 'pyproject.toml'
            - 'csrc/**'
            - 'requirements/common.txt'
            - 'requirements/build.txt'
            - 'lmcache/__init__.py'
            - '.github/workflows/build_cpu_artifacts.yml'

env:
    LC_ALL: en_US.UTF-8

defaults:
    run:
        shell: bash

# Cancel stale runs per ref.
concurrency:
    group: ${{ github.workflow }}-${{ github.ref }}
    cancel-in-progress: true

permissions:
    contents: read

jobs:
    build-cpu-artifacts:
        name: Build CPU artifacts
        runs-on: ubuntu-latest
        steps:
            - name: "Harden Runner"
              uses: step-security/harden-runner@20cf305ff2072d973412fa9b1e3a4f227bda3c76 # v2.14.0
              with:
                disable-sudo-and-containers: false
                egress-policy: audit

            - name: Checkout code
              uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
              with:
                fetch-depth: 0

            - name: Remove non-release tags
              run: git tag -l | grep -vE '^v[0-9]+\.[0-9]+\.[0-9]+$' | xargs -r git tag -d

            - name: Setup Python 3.13
              uses: actions/setup-python@83679a892e2d95755f2dac6acb0bfd1e9ac5d548 # v6.1.0
              with:
                python-version: "3.13"

            - name: Install build tooling and CPU torch
              run: |
                python -m pip install --upgrade pip
                pip install --index-url https://download.pytorch.org/whl/cpu torch
                # Pre-install build deps for --no-isolation below.
                pip install -r requirements/build.txt
                pip install build

            - name: Clean up release artifacts
              run: |
                rm -rf dist/

            - name: Build CPU-only wheel (common C++ extensions, no GPU backend)
              # --skip-dependency-check: the pre-installed CPU torch may not
              # match pyproject.toml's exact build-system pin, but is ABI-
              # compatible for compiling CppExtensions.
              run: |
                NO_GPU_EXT=1 python -m build --wheel --no-isolation \
                  --skip-dependency-check

            - name: Verify CPU wheel contents
              run: |
                set -e
                # Required: common C++ extensions.
                for mod in native_storage_ops lmcache_redis lmcache_fs; do
                  if ! unzip -l dist/lmcache-*.whl | grep -qE "lmcache/${mod}\..*\.so"; then
                    echo "::error::missing common C++ extension: ${mod}"
                    exit 1
                  fi
                done
                # Forbidden: GPU extensions.
                for mod in c_ops xpu_ops; do
                  if unzip -l dist/lmcache-*.whl | grep -qE "lmcache/${mod}\..*\.so"; then
                    echo "::error::unexpected GPU extension in CPU wheel: ${mod}"
                    exit 1
                  fi
                done

            - name: Smoke-test CPU wheel
              # Run from $RUNNER_TEMP so Python resolves `lmcache` from the
              # installed wheel, not the checkout on CWD.
              working-directory: ${{ runner.temp }}
              run: |
                set -e
                pip install ${{ github.workspace }}/dist/lmcache-*.whl
                python -c "
                import lmcache
                assert lmcache.torch_device_type == 'cpu', lmcache.torch_device_type
                "
                python -c "import lmcache.native_storage_ops"
                python -c "import lmcache.lmcache_redis"
                python -c "import lmcache.lmcache_fs"
                # c_ops resolves to the python_ops_fallback shim on CPU.
                python -c "
                import sys, lmcache, lmcache.c_ops
                assert sys.modules['lmcache.c_ops'].__name__ == 'lmcache.python_ops_fallback'
                "

            - name: Upload CPU release artifacts to GHA
              uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
              with:
                name: release-cpu-artifacts
                path: dist/