diff --git a/scripts/audit/check_completeness.py b/scripts/audit/check_completeness.py
new file mode 100644
index 00000000..79d1a11f
--- /dev/null
+++ b/scripts/audit/check_completeness.py
@@ -0,0 +1,31 @@
+"""Phase 9 completeness check: folder set vs row set diff."""
+from __future__ import annotations
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent.parent))
+from scripts.audit.generate_chronology import walk_track_folders  # noqa: E402
+
+folders: set[str] = set()
+for parent in (Path("conductor/tracks"), Path("conductor/archive")):
+    if parent.is_dir():
+        for child in parent.iterdir():
+            if child.is_dir():
+                folders.add(child.name)
+
+rows = walk_track_folders(Path("conductor"))
+row_ids = {r["track_id"] for r in rows}
+
+missing_folders = folders - row_ids
+extra_ids = row_ids - folders
+
+print(f"Total folders: {len(folders)}")
+print(f"Total row IDs in chronology.md: {len(row_ids)}")
+print(f"Folders without rows: {len(missing_folders)}")
+if missing_folders:
+    for f in sorted(missing_folders):
+        print(f"  MISSING: {f}")
+print(f"Rows without folders: {len(extra_ids)}")
+if extra_ids:
+    for x in sorted(extra_ids):
+        print(f"  EXTRA: {x}")