further changes to nvidia.py

src/llama_stack/providers/remote/safety/nvidia/nvidia.py

@@ -131,8 +131,7 @@ class NeMoGuardrails:
             messages (List[Message]): A list of Message objects to be checked for safety violations.
 
         Returns:
-            RunShieldResponse: If the response indicates a violation ("blocked" status), returns a
-            RunShieldResponse with a SafetyViolation; otherwise, returns a RunShieldResponse with violation set to None.
+            RunShieldResponse: Response with SafetyViolation if content is blocked, None otherwise.
 
         Raises:
             requests.HTTPError: If the POST request fails.
@@ -143,16 +142,38 @@ class NeMoGuardrails:
         }
         response = await self._guardrails_post(path="/v1/chat/completions", data=request_data)
 
-        if response["status"] == "blocked":
-            user_message = "Sorry I cannot do this."
-            metadata = response["rails_status"]
+        # Support legacy format with explicit status field
+        if "status" in response and response["status"] == "blocked":
+            return RunShieldResponse(
+                violation=SafetyViolation(
+                    user_message="Sorry I cannot do this.",
+                    violation_level=ViolationLevel.ERROR,
+                    metadata=response.get("rails_status", {}),
+                )
+            )
+
+        # NOTE: The implementation targets the actual behavior of the NeMo Guardrails server
+        # as defined in 'nemoguardrails/server/api.py'. The 'RequestBody' class accepts
+        # 'config_id' at the top level, and 'ResponseBody' returns a 'messages' array,
+        # distinct from the OpenAI 'choices' format often referenced in documentation.
+
+        response_messages = response.get("messages", [])
+        if response_messages:
+            content = response_messages[0].get("content", "").strip()
+        else:
+            choices = response.get("choices", [])
+            if choices:
+                content = choices[0].get("message", {}).get("content", "").strip()
+            else:
+                content = ""
+
+        refusal_phrases = ["sorry i cannot do this", "i cannot help with that", "i can't assist with that"]
+        is_blocked = not content or any(phrase in content.lower() for phrase in refusal_phrases)
 
         return RunShieldResponse(
             violation=SafetyViolation(
-                    user_message=user_message,
+                user_message="Sorry I cannot do this.",
                 violation_level=ViolationLevel.ERROR,
-                    metadata=metadata,
+                metadata={"reason": "Content violates safety guidelines", "response": content or "(empty)"},
+            ) if is_blocked else None
         )
-            )
-
-        return RunShieldResponse(violation=None)