diff --git a/app/frontend/src/type/annotation.ts b/app/frontend/src/type/annotation.ts
index 0fdfb96..56ff32d 100644
--- a/app/frontend/src/type/annotation.ts
+++ b/app/frontend/src/type/annotation.ts
@@ -78,6 +78,7 @@ const IComponent = t.intersection([
   t.type({
     id: IComponentId,
   }),
+  // TODO(xu): don't need this after annotation persistence is fully switched to yjs.
   t.partial({
     draft: t.boolean,
   }),