diff --git a/python/langsmith/testing/_internal.py b/python/langsmith/testing/_internal.py
index 6ba455353..59c15ed0c 100644
--- a/python/langsmith/testing/_internal.py
+++ b/python/langsmith/testing/_internal.py
@@ -458,6 +458,7 @@ def _end_tests(test_suite: _LangSmithTestSuite):
             **git_info,
             "dataset_version": dataset_version,
             "revision_id": ls_env.get_langchain_env_var_metadata().get("revision_id"),
+            "__ls_runner": "pytest",
         },
     )
     if dataset_version and git_info["commit"] is not None: