Split workflow to reduce the available permissions during the build step

Author: kevinbackhouse

.github/workflows/publish-to-pypi.yaml

@@ -6,22 +6,15 @@ on:
       - v[0-9]+.[0-9]+.[0-9]+
 
 jobs:
-  publish:
-    name: Build
+  build:
+    name: Build distribution
     runs-on: ubuntu-latest
 
-    # This environment is required as an input to pypa/gh-action-pypi-publish
-    environment:
-      name: pypi
-      url: https://pypi.org/p/seclab-taskflow-agent
-
     env:
       GITHUB_REPO: ${{ github.repository }}
 
     permissions:
-      contents: write
-      id-token: write  # For trusted publishing
-      attestations: write  # For artifact attestation
+      contents: read
 
     steps:
     - name: Checkout repository
@@ -40,17 +33,42 @@ jobs:
     - name: Build the wheel
       run: python3 -m hatch build
 
-    - name: Attest build provenance
-      uses: actions/attest-build-provenance@96278af6caaf10aea03fd8d33a09a777ca52d62f # v3.2.0
-      with:
-        subject-path: ./dist/*
-
     - name: Upload artifacts
       uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5.0.0
       with:
         name: python-package-distributions
         path: ./dist/
 
+  publish:
+    name: Publish to PyPI
+    needs: build
+    runs-on: ubuntu-latest
+
+    # This environment is required as an input to pypa/gh-action-pypi-publish
+    environment:
+      name: pypi
+      url: https://pypi.org/p/seclab-taskflow-agent
+
+    env:
+      GITHUB_REPO: ${{ github.repository }}
+
+    permissions:
+      contents: write
+      id-token: write  # For trusted publishing
+      attestations: write  # For artifact attestation
+
+    steps:
+    - name: Download distribution artifacts
+      uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+      with:
+        name: python-package-distributions
+        path: ./dist/
+
+    - name: Attest build provenance
+      uses: actions/attest@v4.1.0 # immutable release
+      with:
+        subject-path: ./dist/*
+
     - name: Publish to PyPI
       uses: pypa/gh-action-pypi-publish@ed0c53931b1dc9bd32cbe73a98c7f6766f8a527e # v1.13.0
       with: