fix change selector in workflow

.gitea/workflows/mvs_job.yaml

@@ -11,6 +11,8 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0  # Full history for git diff
 
       - name: Prepare environment
         id: setup
@@ -42,8 +44,9 @@ jobs:
           # Fallback to all .c/.bas files if no changes or no previous commit
           if [ -z "$CHANGED_FILES" ]; then
             echo "=== Debug: No changes found; running fallback find ==="
-            CHANGED_FILES=$(find . -type f \( -name "*.c" -o -name "*.bas" \) | head -1)
-            echo "Fallback files: '${CHANGED_FILES}'"
+            # Find newest .c/.bas by modification time (sort -nr on %T@ timestamp)
+            CHANGED_FILES=$(find . -type f \( -name "*.c" -o -name "*.bas" \) -printf '%T@ %p\n' 2>/dev/null | sort -nr | cut -d' ' -f2- | head -1)
+            echo "Fallback files (newest first): '${CHANGED_FILES}'"
             echo "=== Debug: Fallback complete ==="
           fi