diff --git a/agent/codex_runtime.py b/agent/codex_runtime.py
index e2bcbfc824b2..c2aee3bdf0aa 100644
--- a/agent/codex_runtime.py
+++ b/agent/codex_runtime.py
@@ -281,7 +281,35 @@ def _consume_codex_event_stream(
     terminal_error: Any = None
     saw_terminal = False
 
-    for event in event_iter:
+    event_iter = iter(event_iter)
+    while True:
+        try:
+            event = next(event_iter)
+        except StopIteration:
+            break
+        except TypeError as exc:
+            # The OpenAI SDK's streamed Responses iterator still runs its own
+            # accumulator while yielding SSE events. When chatgpt.com emits a
+            # terminal snapshot whose ``response.output`` is ``null``, the SDK
+            # trips over ``for output in response.output`` and raises
+            # ``TypeError: 'NoneType' object is not iterable`` *after* earlier
+            # ``response.output_item.done`` / ``response.output_text.delta``
+            # events have already arrived. If we have recoverable streamed
+            # state, synthesize the final response from that state instead of
+            # letting a local parse bug poison credential-pool health.
+            if "not iterable" not in str(exc):
+                raise
+            if not collected_output_items and not collected_text_deltas:
+                raise
+            logger.debug(
+                "Codex Responses iterator hit SDK None-output TypeError; "
+                "recovering from streamed state (items=%d, chars=%d)",
+                len(collected_output_items),
+                sum(len(p) for p in collected_text_deltas),
+            )
+            saw_terminal = True
+            terminal_status = terminal_status or "completed"
+            break
         if on_event is not None:
             try:
                 on_event(event)
diff --git a/agent/conversation_loop.py b/agent/conversation_loop.py
index 078c62771ede..efe153affda4 100644
--- a/agent/conversation_loop.py
+++ b/agent/conversation_loop.py
@@ -2914,7 +2914,11 @@ def run_conversation(
                 if is_client_error:
                     # Try fallback before aborting — a different provider
                     # may not have the same issue (rate limit, auth, etc.)
-                    agent._emit_status(f"⚠️ Non-retryable error (HTTP {status_code}) — trying fallback...")
+                    _err_kind = agent._nonretryable_error_kind(status_code, api_error)
+                    agent._emit_status(
+                        f"⚠️ Non-retryable error ({_err_kind}): "
+                        f"{agent._summarize_api_error(api_error)} — trying fallback..."
+                    )
                     if agent._try_activate_fallback():
                         retry_count = 0
                         compression_attempts = 0
@@ -2925,10 +2929,10 @@ def run_conversation(
                             api_kwargs, reason="non_retryable_client_error", error=api_error,
                         )
                     agent._emit_status(
-                        f"❌ Non-retryable error (HTTP {status_code}): "
+                        f"❌ Non-retryable error ({_err_kind}): "
                         f"{agent._summarize_api_error(api_error)}"
                     )
-                    agent._vprint(f"{agent.log_prefix}❌ Non-retryable client error (HTTP {status_code}). Aborting.", force=True)
+                    agent._vprint(f"{agent.log_prefix}❌ Non-retryable client error ({_err_kind}). Aborting.", force=True)
                     agent._vprint(f"{agent.log_prefix}   🔌 Provider: {_provider}  Model: {_model}", force=True)
                     agent._vprint(f"{agent.log_prefix}   🌐 Endpoint: {_base}", force=True)
                     # Actionable guidance for common auth errors
diff --git a/run_agent.py b/run_agent.py
index 9c130d8d294a..cc2d21bb1b57 100644
--- a/run_agent.py
+++ b/run_agent.py
@@ -1563,6 +1563,18 @@ class AIAgent:
         prefix = f"HTTP {status_code}: " if status_code else ""
         return f"{prefix}{raw[:500]}"
 
+    @staticmethod
+    def _nonretryable_error_kind(status_code, api_error) -> str:
+        """Short label for a non-retryable failure.
+
+        Returns ``HTTP <code>`` when an HTTP status is present, otherwise the
+        exception class name. This avoids misleading labels like ``HTTP None``
+        for local parse or transport failures.
+        """
+        if status_code:
+            return f"HTTP {status_code}"
+        return type(api_error).__name__
+
     def _mask_api_key_for_logs(self, key: Any) -> Optional[str]:
         # Azure Foundry Entra ID bearer providers are callables — never
         # invoke them in log paths; identify the auth surface instead.
diff --git a/tests/agent/test_auxiliary_client.py b/tests/agent/test_auxiliary_client.py
index 7e4ddcae133e..ad4a06de3154 100644
--- a/tests/agent/test_auxiliary_client.py
+++ b/tests/agent/test_auxiliary_client.py
@@ -2591,6 +2591,35 @@ class TestCodexAuxiliaryAdapterNullOutputRecovery:
 
         assert response.choices[0].message.content == "aux survived"
 
+    def test_recovers_when_sdk_iterator_raises_none_output_typeerror(self):
+        """Recover from streamed items when the SDK iterator crashes post-stream."""
+        output_item = SimpleNamespace(
+            type="message",
+            content=[SimpleNamespace(type="output_text", text="aux recovered")],
+        )
+        events = [
+            SimpleNamespace(type="response.created"),
+            SimpleNamespace(type="response.output_item.done", item=output_item),
+        ]
+
+        class _BrokenCreateStream:
+            def __iter__(self):
+                for event in events:
+                    yield event
+                raise TypeError("'NoneType' object is not iterable")
+            def close(self): pass
+
+        class FakeResponses:
+            def create(self, **kwargs):
+                return _BrokenCreateStream()
+
+        fake_client = SimpleNamespace(responses=FakeResponses())
+        adapter = _CodexCompletionsAdapter(fake_client, "gpt-5.5")
+
+        response = adapter.create(messages=[{"role": "user", "content": "summarize"}])
+
+        assert response.choices[0].message.content == "aux recovered"
+
 
 # ---------------------------------------------------------------------------
 # Issue #23432 — auxiliary timeout poisons cached client; later aux calls fail
diff --git a/tests/run_agent/test_run_agent.py b/tests/run_agent/test_run_agent.py
index 7e26cfb9dfc0..bb914b6f0275 100644
--- a/tests/run_agent/test_run_agent.py
+++ b/tests/run_agent/test_run_agent.py
@@ -5632,3 +5632,15 @@ class TestMemoryProviderTurnStart:
         # The extracted body uses ``agent.X`` rather than ``self.X``;
         # assert the extracted-form spelling directly.
         assert "on_turn_start(agent._user_turn_count" in src
+
+
+def test_nonretryable_error_kind_surfaces_exception_type_without_status():
+    """Transport/parse failures with no status must not render as HTTP None."""
+    assert (
+        AIAgent._nonretryable_error_kind(
+            None, TypeError("'NoneType' object is not iterable")
+        )
+        == "TypeError"
+    )
+    assert AIAgent._nonretryable_error_kind(0, ValueError("bad")) == "ValueError"
+    assert AIAgent._nonretryable_error_kind(404, RuntimeError("nope")) == "HTTP 404"
diff --git a/tests/run_agent/test_run_agent_codex_responses.py b/tests/run_agent/test_run_agent_codex_responses.py
index 638c1dd99e6f..78a4e396f932 100644
--- a/tests/run_agent/test_run_agent_codex_responses.py
+++ b/tests/run_agent/test_run_agent_codex_responses.py
@@ -161,12 +161,16 @@ class _FakeCreateStream:
     tests use this to drive it through the same code paths the wire does.
     """
 
-    def __init__(self, events):
+    def __init__(self, events, *, iter_error=None):
         self._events = list(events)
+        self._iter_error = iter_error
         self.closed = False
 
     def __iter__(self):
-        return iter(self._events)
+        for event in self._events:
+            yield event
+        if self._iter_error is not None:
+            raise self._iter_error
 
     def close(self):
         self.closed = True
@@ -531,6 +535,48 @@ def test_run_codex_stream_ignores_completed_response_with_null_output(monkeypatc
     assert response.usage.total_tokens == 11
 
 
+def test_run_codex_stream_recovers_after_sdk_none_output_typeerror(monkeypatch):
+    """If the SDK iterator crashes after streamed items arrived, recover from them.
+
+    ``responses.create(stream=True)`` still runs the OpenAI SDK's internal
+    accumulator while yielding SSE events. When chatgpt.com sends a terminal
+    snapshot with ``response.output = null``, the iterator can raise
+    ``TypeError: 'NoneType' object is not iterable`` after earlier
+    ``response.output_item.done`` events were already delivered. The runtime
+    must synthesize the final response from those streamed items instead of
+    surfacing a local parse failure.
+    """
+    agent = _build_agent(monkeypatch)
+    tool_call_item = SimpleNamespace(
+        type="function_call",
+        call_id="call_123",
+        name="lookup_weather",
+        arguments='{"city":"Lahore"}',
+    )
+    create_stream = _FakeCreateStream(
+        [
+            SimpleNamespace(type="response.created"),
+            SimpleNamespace(type="response.output_item.done", item=tool_call_item),
+        ],
+        iter_error=TypeError("'NoneType' object is not iterable"),
+    )
+
+    def _fake_create(**kwargs):
+        assert kwargs.get("stream") is True
+        return create_stream
+
+    agent.client = SimpleNamespace(
+        responses=SimpleNamespace(create=_fake_create),
+    )
+
+    response = agent._run_codex_stream(_codex_request_kwargs())
+    assert response is not None
+    assert create_stream.closed is True
+    assert response.status == "completed"
+    assert response.output == [tool_call_item]
+    assert response.output_text == ""
+
+
 def test_run_conversation_codex_plain_text(monkeypatch):
     agent = _build_agent(monkeypatch)
     monkeypatch.setattr(agent, "_interruptible_api_call", lambda api_kwargs: _codex_message_response("OK"))