ci: make Python lint/test job branch-tolerant

.github/workflows/ci.yml

@@ -20,45 +20,71 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Set up Python
+      - name: Detect Python project
+        id: pyproject
+        run: |
+          if [ -f backend/pyproject.toml ]; then
+            echo "exists=true" >> "$GITHUB_OUTPUT"
+            echo "path=backend" >> "$GITHUB_OUTPUT"
+          elif [ -f pyproject.toml ]; then
+            echo "exists=true" >> "$GITHUB_OUTPUT"
+            echo "path=." >> "$GITHUB_OUTPUT"
+          else
+            echo "exists=false" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Set up Python (with cache)
+        if: steps.pyproject.outputs.exists == 'true'
         uses: actions/setup-python@v5
         with:
           python-version: "3.12"
           cache: pip
+          cache-dependency-path: ${{ steps.pyproject.outputs.path }}/pyproject.toml
+
+      - name: Set up Python (without cache, no pyproject.toml yet)
+        if: steps.pyproject.outputs.exists != 'true'
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
 
       - name: Install dependencies
+        if: steps.pyproject.outputs.exists == 'true'
+        working-directory: ${{ steps.pyproject.outputs.path }}
         run: |
           python -m pip install --upgrade pip
-          if [ -f pyproject.toml ]; then
-            pip install -e ".[dev]" || true
-          else
-            echo "Skipping — no pyproject.toml yet"
-            exit 0
-          fi
+          pip install -e ".[dev]"
 
       - name: Ruff lint
-        if: hashFiles('pyproject.toml') != ''
+        if: steps.pyproject.outputs.exists == 'true'
+        working-directory: ${{ steps.pyproject.outputs.path }}
         run: ruff check .
 
       - name: Ruff format check
-        if: hashFiles('pyproject.toml') != ''
+        if: steps.pyproject.outputs.exists == 'true'
+        working-directory: ${{ steps.pyproject.outputs.path }}
         run: ruff format --check .
 
       - name: Mypy
-        if: hashFiles('pyproject.toml') != ''
-        run: mypy app/ || true   # warn-only until app/ has content
+        if: steps.pyproject.outputs.exists == 'true'
+        working-directory: ${{ steps.pyproject.outputs.path }}
+        run: mypy app/
 
       - name: Tests
-        if: hashFiles('pyproject.toml') != ''
+        if: steps.pyproject.outputs.exists == 'true'
+        working-directory: ${{ steps.pyproject.outputs.path }}
         run: pytest --cov=app --cov-report=xml -v
 
       - name: Upload coverage
-        if: always() && hashFiles('coverage.xml') != ''
+        if: always() && hashFiles('backend/coverage.xml', 'coverage.xml') != ''
         uses: codecov/codecov-action@v4
         with:
-          files: coverage.xml
+          files: backend/coverage.xml,coverage.xml
           fail_ci_if_error: false
 
+      - name: No-op (no Python project yet — skipped)
+        if: steps.pyproject.outputs.exists != 'true'
+        run: echo "No pyproject.toml found — skipping Python checks for this branch"
+
   go:
     name: Go — vet, test
     runs-on: ubuntu-24.04