Fix API stability check workflow to install griffe and improve reporting

The griffe command was failing silently because griffe was not installed.
This commit fixes the workflow to properly install griffe and improves
error reporting.

Changes:
- Add explicit griffe installation step
- Add continue-on-error to capture exit codes
- Consolidate reporting into single step with if: always()
- Handle three states: success, warning (breaking changes), and failure
- Capture and report exit codes for better debugging
- Add proper GitHub notices, warnings, and summaries for all states

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: RonnyPfannschmidt

.github/workflows/api-check.yml

@@ -32,22 +32,48 @@ jobs:
         run: |
           pip install -U pip setuptools
           pip install -e .[test]
+          pip install griffe
 
       - name: Run griffe API check
         id: griffe-check
+        continue-on-error: true
         run: |
+          echo "Running griffe API stability check..."
           if griffe check setuptools_scm -ssrc -f github; then
             echo "api_check_result=success" >> $GITHUB_OUTPUT
+            echo "exit_code=0" >> $GITHUB_OUTPUT
           else
+            exit_code=$?
             echo "api_check_result=warning" >> $GITHUB_OUTPUT
-            echo "API stability check detected changes but will not fail the build" >> $GITHUB_STEP_SUMMARY
+            echo "exit_code=$exit_code" >> $GITHUB_OUTPUT
+            exit $exit_code
           fi
 
       - name: Report API check result
-        if: steps.griffe-check.outputs.api_check_result == 'warning'
+        if: always()
         uses: actions/github-script@v8
         with:
           script: |
-            core.warning('API stability check detected breaking changes. Please review the API changes above.')
-            core.summary.addRaw('⚠️ API Stability Warning: Breaking changes detected in the public API')
-            await core.summary.write()
+            const result = '${{ steps.griffe-check.outputs.api_check_result }}'
+            const exitCode = '${{ steps.griffe-check.outputs.exit_code }}'
+
+            if (result === 'success') {
+              core.notice('API stability check passed - no breaking changes detected')
+              await core.summary
+                .addHeading('✅ API Stability Check: Passed', 2)
+                .addRaw('No breaking changes detected in the public API')
+                .write()
+            } else if (result === 'warning') {
+              core.warning(`API stability check detected breaking changes (exit code: ${exitCode}). Please review the API changes above.`)
+              await core.summary
+                .addHeading('⚠️ API Stability Warning', 2)
+                .addRaw('Breaking changes detected in the public API. Please review the changes reported above.')
+                .addRaw(`\n\nExit code: ${exitCode}`)
+                .write()
+            } else {
+              core.error('API stability check failed to run properly')
+              await core.summary
+                .addHeading('❌ API Stability Check: Failed', 2)
+                .addRaw('The griffe check failed to execute. This may indicate griffe is not installed or there was an error.')
+                .write()
+            }