diff --git a/run_agent.py b/run_agent.py
index 8e1fbfed194..fa8c22d8455 100644
--- a/run_agent.py
+++ b/run_agent.py
@@ -9499,7 +9499,16 @@ class AIAgent:
                         # Check for x-openrouter-provider or similar metadata
                         if provider_name == "Unknown" and response:
                             # Log all response attributes for debugging
-                            resp_attrs = {k: str(v)[:100] for k, v in vars(response).items() if not k.startswith('_')}
+                            try:
+                                if hasattr(response, "__dict__"):
+                                    _resp_dict = response.__dict__
+                                elif hasattr(response, "model_dump"):
+                                    _resp_dict = response.model_dump()
+                                else:
+                                    _resp_dict = {}
+                                resp_attrs = {k: str(v)[:100] for k, v in _resp_dict.items() if not k.startswith('_')}
+                            except (TypeError, AttributeError):
+                                resp_attrs = {}
                             if self.verbose_logging:
                                 logging.debug(f"Response attributes for invalid response: {resp_attrs}")
                         
diff --git a/tests/run_agent/test_run_agent_codex_responses.py b/tests/run_agent/test_run_agent_codex_responses.py
index 81213aaf673..4b4d13e8279 100644
--- a/tests/run_agent/test_run_agent_codex_responses.py
+++ b/tests/run_agent/test_run_agent_codex_responses.py
@@ -1310,3 +1310,39 @@ def test_preflight_codex_input_deduplicates_reasoning_ids(monkeypatch):
     # IDs must be stripped — with store=False the API 404s on id lookups.
     for it in reasoning_items:
         assert "id" not in it
+
+
+# ---------------------------------------------------------------------------
+# Issue #6133 — vars() on response objects that lack __dict__ raises TypeError.
+# The fix must use a safe fallback (hasattr __dict__ / model_dump) instead.
+# ---------------------------------------------------------------------------
+
+
+def test_run_conversation_slots_response_does_not_raise(monkeypatch):
+    """Response objects that define __slots__ (and therefore have no __dict__)
+    must not crash the invalid-response debug logging path."""
+
+    class _SlotsResponse:
+        __slots__ = ("output", "output_text", "status")
+
+        def __init__(self):
+            self.output = []
+            self.output_text = None
+            self.status = "completed"
+
+    agent = _build_agent(monkeypatch)
+    calls = {"n": 0}
+
+    def _fake_api(api_kwargs):
+        calls["n"] += 1
+        if calls["n"] == 1:
+            return _SlotsResponse()
+        return _codex_message_response("Recovered")
+
+    monkeypatch.setattr(agent, "_interruptible_api_call", _fake_api)
+
+    result = agent.run_conversation("ping")
+
+    assert calls["n"] >= 2
+    assert result["completed"] is True
+    assert result["final_response"] == "Recovered"