fix(guardrails): snapshot model_call_details before serializing noma v2 scan payload

litellm/proxy/guardrails/guardrail_hooks/noma/noma_v2.py

@@ -131,9 +131,18 @@ class NomaV2Guardrail(CustomGuardrail):
         logging_obj: Optional["LiteLLMLoggingObj"],
         application_id: Optional[str],
     ) -> dict:
-        payload_request_data = self._sanitize_payload_for_transport(request_data)
-        if logging_obj is not None:
-            payload_request_data["litellm_logging_obj"] = getattr(logging_obj, "model_call_details", None)
+        model_call_details = getattr(logging_obj, "model_call_details", None) if logging_obj is not None else None
+        request_data_to_send = (
+            {
+                **request_data,
+                "litellm_logging_obj": dict(model_call_details)
+                if isinstance(model_call_details, dict)
+                else model_call_details,
+            }
+            if logging_obj is not None
+            else request_data
+        )
+        payload_request_data = self._sanitize_payload_for_transport(request_data_to_send)
 
         payload: dict[str, Any] = {
             "inputs": inputs,
@@ -157,7 +166,7 @@ class NomaV2Guardrail(CustomGuardrail):
 
         try:
             json_str = json.dumps(payload, default=_default)
-        except (ValueError, TypeError):
+        except (ValueError, TypeError, RuntimeError):
             json_str = safe_dumps(payload)
 
         safe_payload = safe_json_loads(json_str, default={})

tests/test_litellm/proxy/guardrails/guardrail_hooks/test_noma_v2.py

@@ -236,6 +236,46 @@ class TestNomaV2Configuration:
         assert "logging_obj" not in payload
         assert request_data["litellm_logging_obj"] == "<Logging object>"
 
+    def test_build_scan_payload_snapshots_live_model_call_details(
+        self, noma_v2_guardrail
+    ):
+        """Regression test: model_call_details is mutated by logging handlers on other
+        threads, so serializing it by reference raises RuntimeError('dictionary changed
+        size during iteration')."""
+
+        class _MutatingOnSerialize:
+            def __init__(self, target: dict) -> None:
+                self._target = target
+
+            def model_dump(self) -> dict:
+                self._target[f"late_key_{len(self._target)}"] = "written_by_logging"
+                return {"serialized": True}
+
+        model_call_details: dict = {
+            "model": "gpt-4.1-mini",
+            "call_type": "acompletion",
+        }
+        model_call_details["standard_callback_dynamic_params"] = _MutatingOnSerialize(
+            model_call_details
+        )
+
+        class _LoggingObj:
+            def __init__(self) -> None:
+                self.model_call_details = model_call_details
+
+        payload = noma_v2_guardrail._build_scan_payload(
+            inputs={"texts": ["hello"]},
+            request_data={"messages": [{"role": "user", "content": "hello"}]},
+            input_type="request",
+            logging_obj=_LoggingObj(),
+            application_id="test-app",
+        )
+
+        sent = payload["request_data"]["litellm_logging_obj"]
+        assert sent["model"] == "gpt-4.1-mini"
+        assert sent["standard_callback_dynamic_params"] == {"serialized": True}
+        assert not any(key.startswith("late_key_") for key in sent)
+
     @pytest.mark.asyncio
     async def test_call_noma_scan_sanitizes_response_model_dump_object(
         self, noma_v2_guardrail