diff --git a/server/client_session.py b/server/client_session.py
index d5c11b6..399abec 100644
--- a/server/client_session.py
+++ b/server/client_session.py
@@ -14,6 +14,7 @@ class ClientSession:
     connected_at: float
     last_packet_at: float | None = None
     last_transform: dict[str, Any] | None = None
+    last_transform_monotonic: float | None = None
     packets_received: int = 0
     packets_sent: int = 0
     packets_broadcast: int = 0
@@ -32,9 +33,15 @@ class ClientSession:
             self.packets_received += 1
             return self.packets_received
 
-    def record_transform(self, packet: dict[str, Any]) -> None:
+    def record_transform(self, packet: dict[str, Any], accepted_monotonic: float | None = None) -> None:
         with self._lock:
             self.last_transform = dict(packet)
+            self.last_transform_monotonic = accepted_monotonic
+
+    def get_last_transform_anchor(self) -> tuple[dict[str, Any] | None, float | None]:
+        with self._lock:
+            transform = dict(self.last_transform) if self.last_transform is not None else None
+            return transform, self.last_transform_monotonic
 
     def record_sent(self, *, broadcast: bool = False) -> None:
         with self._lock: