diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py

index 69abf6fa87..41d9111019 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -57,7 +57,22 @@ class SQLBaseStore(metaclass=ABCMeta):
         token: int,
         rows: Iterable[Any],
     ) -> None:
-        pass
+        """
+        Used by storage classes to invalidate caches based on incoming replication data. These
+        must not update any ID generators, use `process_replication_position`.
+        """
+
+    def process_replication_position(  # noqa: B027 (no-op by design)
+        self,
+        stream_name: str,
+        instance_name: str,
+        token: int,
+    ) -> None:
+        """
+        Used by storage classes to advance ID generators based on incoming replication data. This
+        is called after process_replication_rows such that caches are invalidated before any token
+        positions advance.
+        """
 
     def _invalidate_state_caches(
         self, room_id: str, members_changed: Collection[str]