diff --git a/lib_run_single.py b/lib_run_single.py
index 78051b8..277cc04 100644
--- a/lib_run_single.py
+++ b/lib_run_single.py
@@ -67,7 +67,8 @@ def run_single_example(agent, env, example, max_steps, instruction, args, exampl
                     "reward": reward,
                     "done": done,
                     "info": info,
-                    "screenshot_file": f"step_{step_idx + 1}_{action_timestamp}.png"
+                    "screenshot_file": f"step_{step_idx + 1}_{action_timestamp}.png",
+                    "a11y_tree": obs.get("accessibility_tree") if isinstance(obs, dict) else None
                 }))
                 f.write("\n")
             if done: