diff --git a/unity/org.gamecult.cultlib/CHANGELOG.md b/unity/org.gamecult.cultlib/CHANGELOG.md
index 0b7d3c90..21a8227d 100644
--- a/unity/org.gamecult.cultlib/CHANGELOG.md
+++ b/unity/org.gamecult.cultlib/CHANGELOG.md
@@ -31,6 +31,11 @@ All notable changes to this package are documented in this file.
   stored under, as its backing store last read or wrote it. It differs from
   `Descriptor.SchemaId` only for a record loaded under compatible schema drift
   that its store has not rewritten since.
+- `CacheBackingStore.MarkWritten(CultStoredDocument)` (protected): a backing
+  store records that its completed durable write stored a record under its
+  descriptor, so `PersistedSchemaId` follows the rewrite. The single-file and
+  directory stores mark every record they rewrite; a custom store calls it for
+  each record its own write rewrote.
 
 ### Changed