diff --git a/agent/codex_runtime.py b/agent/codex_runtime.py
index 34ef399b261ae..65cc3cd1a0d07 100644
--- a/agent/codex_runtime.py
+++ b/agent/codex_runtime.py
@@ -46,7 +46,10 @@ def _codex_request_failure_details(error: BaseException) -> tuple[int | None, st
         exception_classes.append(type(current).__name__)
 
         if request_body_bytes is None:
-            request = getattr(current, "request", None)
+            try:
+                request = getattr(current, "request", None)
+            except Exception:
+                request = None
             if request is not None:
                 try:
                     content = request.content
diff --git a/tests/agent/test_codex_request_transport_diagnostics.py b/tests/agent/test_codex_request_transport_diagnostics.py
index deea310fdb351..0cb4567d2a312 100644
--- a/tests/agent/test_codex_request_transport_diagnostics.py
+++ b/tests/agent/test_codex_request_transport_diagnostics.py
@@ -9,7 +9,16 @@ import httpx
 import pytest
 from openai import APIConnectionError
 
-from agent.codex_runtime import run_codex_stream
+from agent.codex_runtime import _codex_request_failure_details, run_codex_stream
+
+
+def test_transport_failure_without_attached_request_reports_unknown_size():
+    error = httpx.RemoteProtocolError("connection closed")
+
+    request_body_bytes, exception_chain = _codex_request_failure_details(error)
+
+    assert request_body_bytes is None
+    assert exception_chain == "RemoteProtocolError"
 
 
 def test_transport_failure_logs_exact_request_bytes_and_class_chain(caplog):