feat: add comprehensive debugging to maintenance workflow

- Add detailed git state verification to 'Compute impacted modules' step
- Test different git diff approaches before running the script
- Add bash debug mode (set -x) for full command tracing
- Enhanced error handling in test_discovery.py with full traceback
- Track and display which git command was actually executed
- Add exit code and output parsing for better debugging

This will help diagnose exactly what's happening in GitHub Actions
instead of the current whack-a-mole debugging approach.

Author: markpollack

.github/scripts/test_discovery.py

@@ -20,6 +20,7 @@ class CITestDiscovery:
 
     def __init__(self, repo_root: Path = Path(".")):
         self.repo_root = Path(repo_root)
+        self._last_git_command = None
 
     def modules_from_diff(self, base_ref: Optional[str] = None, verbose: bool = False) -> str:
         """Get affected modules from git diff (for GitHub Actions)"""
@@ -31,6 +32,7 @@ def modules_from_diff(self, base_ref: Optional[str] = None, verbose: bool = Fals
             if verbose:
                 detected_base = base_ref if base_ref else self._detect_default_base()
                 print(f"Detected base ref: {detected_base}", file=sys.stderr)
+                print(f"Git diff strategy used: {self._get_last_git_command()}", file=sys.stderr)
                 print(f"Changed files ({len(changed_files)}):", file=sys.stderr)
                 for file in changed_files[:10]:  # Limit to first 10 for readability
                     print(f"  - {file}", file=sys.stderr)
@@ -88,6 +90,7 @@ def _get_changed_files(self, base_ref: Optional[str] = None) -> List[str]:
                 cmd = ["git", "diff", "--name-only", "HEAD~1..HEAD"]
 
             # Execute the git diff command
+            self._last_git_command = ' '.join(cmd)  # Store for debugging
             result = subprocess.run(
                 cmd, 
                 cwd=self.repo_root,
@@ -102,9 +105,15 @@ def _get_changed_files(self, base_ref: Optional[str] = None) -> List[str]:
         except subprocess.CalledProcessError as e:
             print(f"Git command failed: {e}", file=sys.stderr)
             print(f"Command: {' '.join(e.cmd) if hasattr(e, 'cmd') else 'unknown'}", file=sys.stderr)
+            print(f"Exit code: {e.returncode}", file=sys.stderr)
+            print(f"Stdout: {e.stdout if hasattr(e, 'stdout') else 'N/A'}", file=sys.stderr)
+            print(f"Stderr: {e.stderr if hasattr(e, 'stderr') else 'N/A'}", file=sys.stderr)
             return []
         except Exception as e:
             print(f"Error getting changed files: {e}", file=sys.stderr)
+            print(f"Error type: {type(e).__name__}", file=sys.stderr)
+            import traceback
+            print(f"Traceback: {traceback.format_exc()}", file=sys.stderr)
             return []
 
     def _discover_affected_modules(self, changed_files: List[str]) -> List[str]:
@@ -188,6 +197,10 @@ def _detect_default_base(self) -> str:
             return f"HEAD~1 (single commit - branch {branch})"
         else:
             return "HEAD~1 (single commit - fallback)"
+    
+    def _get_last_git_command(self) -> str:
+        """Get the last git command executed for debugging"""
+        return self._last_git_command or "No git command executed yet"
 
 
 def modules_from_diff_cli():

.github/workflows/maintenance-fast.yml

@@ -39,8 +39,47 @@ jobs:
       - name: Compute impacted modules
         id: mods
         run: |
-          MODS=$(python3 .github/scripts/test_discovery.py modules-from-diff --base "origin/$GITHUB_REF_NAME" --verbose)
-          echo "modules=$MODS" >> "$GITHUB_OUTPUT"
+          echo "=== Module Detection Debug Info ==="
+          echo "Environment variables:"
+          echo "  GITHUB_REF_NAME: $GITHUB_REF_NAME"
+          echo "  GITHUB_REF: $GITHUB_REF"
+          echo "  PWD: $(pwd)"
+          echo ""
+          
+          echo "Git state verification:"
+          echo "  HEAD: $(git rev-parse HEAD 2>/dev/null || echo 'FAILED')"
+          echo "  HEAD~1: $(git rev-parse HEAD~1 2>/dev/null || echo 'NOT AVAILABLE')"
+          echo "  Branch: $(git branch --show-current 2>/dev/null || echo 'DETACHED')"
+          echo ""
+          
+          echo "Testing different git diff approaches:"
+          echo "1. HEAD~1..HEAD:"
+          git diff --name-only HEAD~1..HEAD 2>&1 | head -10 || echo "  FAILED: $?"
+          
+          echo "2. git show HEAD:"  
+          git show --name-only --format= HEAD 2>&1 | head -10 || echo "  FAILED: $?"
+          
+          echo "3. Recent commits:"
+          git log --oneline -3 2>/dev/null || echo "  Git log failed"
+          echo ""
+          
+          echo "=== Running test_discovery.py with full debugging ==="
+          set -x  # Enable bash debug mode
+          MODS=$(python3 .github/scripts/test_discovery.py modules-from-diff --base "origin/$GITHUB_REF_NAME" --verbose 2>&1)
+          EXIT_CODE=$?
+          set +x  # Disable bash debug mode
+          
+          echo ""
+          echo "=== Test Discovery Results ==="
+          echo "Exit code: $EXIT_CODE"
+          echo "Output:"
+          echo "$MODS"
+          echo ""
+          
+          # Extract just the module list (last line that isn't stderr logging)
+          MODULE_LIST=$(echo "$MODS" | grep -v "^Detected base ref:" | grep -v "^Changed files" | grep -v "^Final module list:" | tail -1)
+          echo "Extracted modules: '$MODULE_LIST'"
+          echo "modules=$MODULE_LIST" >> "$GITHUB_OUTPUT"
 
       - name: Test affected modules with integration tests
         env: