Simplify CI to basic Python 3.8 Linux build

Start fresh with a simple workflow:
- Direct python -m build instead of cibuildwheel
- Build CFD library explicitly before wheel
- No stable ABI complexity
- Python 3.8 on Linux only

Previous configs backed up to backups/

Author: shaia

.github/workflows/build-wheels.yml

@@ -2,250 +2,102 @@ name: Build and Test Wheels
 
 on:
   push:
-    branches: [main, master]
-    tags:
-      - "v*"
+    branches: [main, master, feature/ci-cd]
   pull_request:
     branches: [main, master]
-  release:
-    types: [published]
-  # Allow manual triggering or remote triggering via GitHub CLI/API
-  # (used by cfd repo's version-release.yml via: gh workflow run build-wheels.yml)
   workflow_dispatch:
-    inputs:
-      cfd_ref:
-        description: "CFD library ref (tag/branch/commit). Leave empty to auto-detect."
-        required: false
-        default: ""
 
 jobs:
-  build_wheels:
-    name: Build wheels on ${{ matrix.os }}
-    runs-on: ${{ matrix.os }}
-    strategy:
-      matrix:
-        # Build only on Linux for now (simplified debugging)
-        os: [ubuntu-latest]
+  build_wheel:
+    name: Build wheel on Linux
+    runs-on: ubuntu-latest
 
     steps:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
-      # Determine which version of CFD library to use
-      # Priority: workflow_dispatch input > latest cfd release tag
-      # This ensures we always build against stable, tested cfd releases
-      - name: Determine CFD library version
-        id: cfd-version
-        shell: bash
-        env:
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          # Check for workflow_dispatch input first
-          if [[ -n "${{ github.event.inputs.cfd_ref }}" ]]; then
-            echo "ref=${{ github.event.inputs.cfd_ref }}" >> $GITHUB_OUTPUT
-            echo "Using CFD library ref from input: ${{ github.event.inputs.cfd_ref }}"
-          else
-            # Fetch the latest release tag from cfd repo
-            LATEST_TAG=$(gh api repos/${{ github.repository_owner }}/cfd/releases/latest --jq '.tag_name' 2>/dev/null || echo "")
-
-            if [[ -n "$LATEST_TAG" ]]; then
-              echo "ref=$LATEST_TAG" >> $GITHUB_OUTPUT
-              echo "Using latest CFD release: $LATEST_TAG"
-            else
-              # Fallback to master if no releases exist
-              echo "ref=master" >> $GITHUB_OUTPUT
-              echo "No CFD releases found, falling back to master branch"
-            fi
-          fi
-
-      # Checkout the CFD C library into 'src/cfd_lib' subdirectory
-      # This location is inside the source tree so it's accessible from cibuildwheel
-      # build environments (including Linux Docker containers where source is mounted)
+      # Checkout CFD C library
       - name: Checkout CFD C library
         uses: actions/checkout@v4
         with:
           repository: ${{ github.repository_owner }}/cfd
-          path: src/cfd_lib
-          ref: ${{ steps.cfd-version.outputs.ref }}
+          path: cfd
           fetch-depth: 0
 
-      # Build wheels using cibuildwheel
-      # Configuration is in pyproject.toml - we only override CFD_ROOT for CI
-      # (pyproject.toml defaults to ../cfd for local dev, CI uses ./src/cfd_lib)
-      - name: Build wheels
-        uses: pypa/cibuildwheel@v2.21.3
+      - name: Set up Python 3.8
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.8"
+
+      - name: Install build dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install build scikit-build-core setuptools-scm
+
+      - name: Build CFD library
+        run: |
+          cmake -S cfd -B cfd/build -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF -DCMAKE_POSITION_INDEPENDENT_CODE=ON
+          cmake --build cfd/build --config Release
+          echo "=== CFD library built ==="
+          ls -la cfd/build/lib/
+
+      - name: Build wheel
         env:
-          # Override CFD_ROOT to point to the cfd checkout inside the source tree
-          # All other settings (build flags, before-build, etc.) come from pyproject.toml
-          CIBW_ENVIRONMENT: "CMAKE_BUILD_TYPE=Release CFD_STATIC_LINK=ON CFD_USE_STABLE_ABI=ON CFD_ROOT=./src/cfd_lib"
-          # Enable verbose output to see CMake and compiler commands
-          CIBW_BUILD_VERBOSITY: "3"
-
-      - name: List wheel contents for debugging
-        shell: bash
+          CFD_ROOT: ./cfd
+          CFD_STATIC_LINK: "ON"
+          CFD_USE_STABLE_ABI: "OFF"
+        run: |
+          python -m build --wheel
+          echo "=== Wheel built ==="
+          ls -la dist/
+
+      - name: Inspect wheel contents
         run: |
-          echo "=== Wheels built ==="
-          ls -la wheelhouse/
-          echo ""
-          echo "=== Inspecting wheel contents ==="
-          for wheel in wheelhouse/*.whl; do
-            echo "--- $wheel ---"
-            python -m zipfile -l "$wheel" | grep -E '\.(so|pyd|dylib)$' || echo "No extension found!"
+          for wheel in dist/*.whl; do
+            echo "=== Contents of $wheel ==="
+            python -m zipfile -l "$wheel"
           done
 
       - uses: actions/upload-artifact@v4
         with:
-          name: wheels-${{ matrix.os }}
-          path: ./wheelhouse/*.whl
+          name: wheel
+          path: dist/*.whl
 
-  build_sdist:
-    name: Build source distribution
+  test_wheel:
+    name: Test wheel
+    needs: [build_wheel]
     runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-
-      - name: Build sdist
-        run: pipx run build --sdist
-
-      - uses: actions/upload-artifact@v4
-        with:
-          name: sdist
-          path: dist/*.tar.gz
-
-  test_package:
-    name: Test package installation
-    needs: [build_wheels]
-    runs-on: ${{ matrix.os }}
-    strategy:
-      matrix:
-        # Test on Linux with Python 3.8 (matches abi3 wheel) and 3.12 (to verify abi3 compat)
-        os: [ubuntu-latest]
-        python-version: ["3.8", "3.12"]
 
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+
+      - name: Set up Python 3.8
+        uses: actions/setup-python@v5
         with:
-          python-version: ${{ matrix.python-version }}
+          python-version: "3.8"
 
       - uses: actions/download-artifact@v4
         with:
-          name: wheels-${{ matrix.os }}
-          path: wheelhouse
-
-      - name: List available wheels
-        shell: bash
-        run: |
-          echo "=== Available wheels ==="
-          ls -la wheelhouse/
-          echo ""
-          echo "=== Python version ==="
-          python --version
-          echo ""
-          echo "=== Wheel contents (looking for .so/.pyd files) ==="
-          for wheel in wheelhouse/*.whl; do
-            echo "--- $wheel ---"
-            python -m zipfile -l "$wheel" | grep -E '\.(so|pyd|dylib)$' || echo "No extension found in wheel!"
-          done
+          name: wheel
+          path: dist
 
-      - name: Install wheel and test dependencies
+      - name: Install wheel
         run: |
           python -m pip install --upgrade pip
-          python -m pip install -v --find-links wheelhouse cfd-python
-          python -m pip install pytest numpy
+          pip install dist/*.whl
+          pip install pytest numpy
 
-      - name: Verify installation
-        shell: bash
+      - name: Test import
         run: |
-          echo "=== Installed package location ==="
-          python -c "import cfd_python; print('Package __file__:', cfd_python.__file__)"
-          echo ""
-          echo "=== Package directory contents ==="
-          python -c "import cfd_python, os; pkgdir=os.path.dirname(cfd_python.__file__); print('Contents:', os.listdir(pkgdir)); exts=[f for f in os.listdir(pkgdir) if '.so' in f or '.pyd' in f]; print('Extensions found:', exts)"
-          echo ""
-          echo "=== Try importing C extension directly ==="
           python -c "
-          import sys, os
           import cfd_python
-          pkgdir = os.path.dirname(cfd_python.__file__)
-          print('Package dir:', pkgdir)
+          print('Package loaded:', cfd_python.__file__)
+          print('Version:', cfd_python.__version__)
           print('Has list_solvers:', hasattr(cfd_python, 'list_solvers'))
-          # Try direct import of the extension
-          try:
-              from cfd_python import cfd_python as ext
-              print('Direct extension import OK')
-              print('Extension has PyInit:', hasattr(ext, '__name__'))
-              print('list_solvers available:', hasattr(ext, 'list_solvers'))
-          except ImportError as e:
-              print('Direct extension import FAILED:', e)
-          # Check __all__
-          print('__all__:', getattr(cfd_python, '__all__', 'NOT DEFINED'))
-          print('__version__:', getattr(cfd_python, '__version__', 'NOT DEFINED'))
+          if hasattr(cfd_python, 'list_solvers'):
+              print('Solvers:', cfd_python.list_solvers())
           "
 
-      - name: Run full test suite
+      - name: Run tests
         run: pytest tests/ -v
-
-  upload_pypi:
-    name: Upload to PyPI
-    needs: [build_wheels, build_sdist, test_package]
-    runs-on: ubuntu-latest
-    # Publish on: release event, tag push (v*), or workflow_dispatch on a tag
-    if: |
-      github.event_name == 'release' ||
-      (github.event_name == 'push' && startsWith(github.ref, 'refs/tags/v')) ||
-      (github.event_name == 'workflow_dispatch' && startsWith(github.ref, 'refs/tags/v'))
-    environment:
-      name: pypi
-      url: https://pypi.org/p/cfd-python
-    permissions:
-      id-token: write
-
-    steps:
-      - uses: actions/download-artifact@v4
-        with:
-          pattern: wheels-*
-          path: dist
-          merge-multiple: true
-
-      - uses: actions/download-artifact@v4
-        with:
-          name: sdist
-          path: dist
-
-      - name: Publish to PyPI
-        uses: pypa/gh-action-pypi-publish@v1.12.4  # Pin to specific version for security
-        with:
-          packages-dir: dist/
-
-  upload_test_pypi:
-    name: Upload to Test PyPI
-    needs: [build_wheels, build_sdist, test_package]
-    runs-on: ubuntu-latest
-    if: github.event_name == 'push' && (github.ref == 'refs/heads/main' || github.ref == 'refs/heads/master')
-    environment:
-      name: testpypi
-      url: https://test.pypi.org/p/cfd-python
-    permissions:
-      id-token: write
-
-    steps:
-      - uses: actions/download-artifact@v4
-        with:
-          pattern: wheels-*
-          path: dist
-          merge-multiple: true
-
-      - uses: actions/download-artifact@v4
-        with:
-          name: sdist
-          path: dist
-
-      - name: Publish to Test PyPI
-        uses: pypa/gh-action-pypi-publish@v1.12.4  # Pin to specific version for security
-        with:
-          repository-url: https://test.pypi.org/legacy/
-          packages-dir: dist/