feat: add weekly dead code detection with proper exit codes (#996)

Adds automated dead code detection that runs weekly and properly reports failures.

- Fix dead code script to return exit code 1 when dead code is detected
- Add weekly GitHub action that runs every Saturday at 4 AM UTC
- Action creates issues with detailed reports when dead code is found
- Integrates with existing @code_is_used decorator system

Co-authored-by: florath-ai-assistant[bot] <Andreas.Florath@telekom.de>

Author: coding-ai-assistant[bot]

.github/workflows/dead-code-detection.yml

@@ -0,0 +1,79 @@
+name: Dead Code Detection
+
+on:
+  # Run weekly on Saturdays at 4 AM UTC
+  schedule:
+    - cron: '0 4 * * 6'
+  # Allow manual triggering
+  workflow_dispatch:
+
+jobs:
+  dead-code-detection:
+    name: Dead Code Detection
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Set up Python 3.11
+      uses: actions/setup-python@v5
+      with:
+        python-version: "3.11"
+        cache: 'pip'
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install -e .[dev]
+
+    - name: Run dead code detection
+      id: dead-code-check
+      run: |
+        python scripts/detect-dead-code.py > dead-code-report.txt 2>&1
+      continue-on-error: true
+
+    - name: Archive dead code detection results
+      uses: actions/upload-artifact@v4
+      if: always()
+      with:
+        name: dead-code-detection-results
+        path: dead-code-report.txt
+        retention-days: 30
+
+    - name: Create issue on dead code detection
+      if: steps.dead-code-check.outcome == 'failure'
+      uses: actions/github-script@v7
+      with:
+        script: |
+          const fs = require('fs');
+          let reportContent = '';
+          try {
+            reportContent = fs.readFileSync('dead-code-report.txt', 'utf8');
+          } catch (error) {
+            reportContent = 'Could not read dead code detection report.';
+          }
+
+          const issue = await github.rest.issues.create({
+            owner: context.repo.owner,
+            repo: context.repo.repo,
+            title: 'Dead Code Detected - ' + new Date().toISOString().split('T')[0],
+            body: `The weekly dead code detection has identified potentially unused functions.
+
+            **Workflow Run:** ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
+
+            ## Dead Code Report
+
+            \`\`\`
+            ${reportContent}
+            \`\`\`
+
+            Please review the identified functions and either:
+            1. Remove them if they are truly unused
+            2. Mark them with \`@code_is_used\` decorator if they are used but not detected by runtime tracing (e.g., polymorphic methods, decorator-replaced methods, etc.)
+
+            See the script documentation in \`scripts/detect-dead-code.py\` for more details on when to use the \`@code_is_used\` decorator.
+
+            [AI-assisted]`,
+            labels: ['maintenance', 'automated', 'dead-code']
+          });
+          console.log('Created issue:', issue.data.html_url);

scripts/detect-dead-code.py

@@ -723,6 +723,11 @@ def main() -> None:
     else:
         print("  No functions discovered.")
 
+    # Exit with error code if dead code was found
+    if dead_functions:
+        import sys
+        sys.exit(1)
+
 
 if __name__ == "__main__":
     main()