fix(session): remove message time replay prefixes

tests/agent/test_auto_compact.py

@@ -223,7 +223,7 @@ class TestAgentLoopTTLParam:
         kwargs = session.get_history.call_args.kwargs
         assert isinstance(kwargs.get("max_tokens"), int)
         assert kwargs["max_tokens"] > 0
-        assert kwargs["include_timestamps"] is True
+        assert set(kwargs) == {"max_messages", "max_tokens", "extend_to_user"}
 
     @pytest.mark.asyncio
     async def test_session_file_cap_archives_and_trims_old_messages(self, tmp_path):