diff --git a/src/thoughtsync/sync.py b/src/thoughtsync/sync.py
index 30a2fcd..5b09756 100644
--- a/src/thoughtsync/sync.py
+++ b/src/thoughtsync/sync.py
@@ -209,12 +209,22 @@ def _assign_note_fields(note: Note, ch: dict) -> None:
 
 
 async def _apply_note_items(db, note: Note, ch: dict) -> None:
-    """Replace the note's checklist items with the client's (items sync inline)."""
-    if note.kind != "list":
-        await db.execute(sa_delete(NoteItem).where(NoteItem.note_id == note.id))
-        return
+    """Replace the note's checklist items with the client's (items sync inline).
+
+    Applies to ANY note. This used to delete every item when the note wasn't
+    `kind == "list"`, which was survivable only because nothing could produce a note
+    holding both a body and items. M13 makes that the normal shape — a checklist is
+    something a note HAS, not something a note IS — and against that shape the old
+    guard was a data-loss path: the first sync after adding a checklist to a note
+    would have wiped it.
+
+    Removed ahead of the UI that can create the state, deliberately, so there is no
+    window in which the two disagree.
+    """
     items = ch.get("items")
     if not isinstance(items, list):
+        # Absent means "not telling us", not "empty". A client that omits the key
+        # leaves what the server has; only an explicit [] clears it.
         return
     await db.execute(sa_delete(NoteItem).where(NoteItem.note_id == note.id))
     for pos, it in enumerate(items):