chore: add user id header to identities get request (#1090)

letta/server/rest_api/routers/v1/identities.py

@@ -51,9 +51,11 @@ def list_identities(
 def retrieve_identity(
     identity_id: str,
     server: "SyncServer" = Depends(get_letta_server),
+    user_id: Optional[str] = Header(None, alias="user_id"),  # Extract user_id from header, default to None if not present
 ):
     try:
-        return server.identity_manager.get_identity(identity_id=identity_id)
+        actor = server.user_manager.get_user_or_default(user_id=user_id)
+        return server.identity_manager.get_identity(identity_id=identity_id, actor=actor)
     except NoResultFound as e:
         raise HTTPException(status_code=404, detail=str(e))