fix(nvidia-safety): correct NeMo Guardrails API endpoint

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

@@ -125,43 +125,57 @@ async def _guardrails_post(self, path: str, data: Any | None):
 
     async def run(self, messages: list[OpenAIMessageParam]) -> RunShieldResponse:
         """
-        Queries the /v1/guardrails/checks endpoint of the NeMo guardrails deployed API.
+        Queries the /v1/chat/completions endpoint of the NeMo guardrails deployed API.
 
         Args:
             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.
         """
         request_data = {
-            "model": self.model,
+            "config_id": self.config_id,
             "messages": [{"role": message.role, "content": message.content} for message in messages],
-            "temperature": self.temperature,
-            "top_p": 1,
-            "frequency_penalty": 0,
-            "presence_penalty": 0,
-            "max_tokens": 160,
-            "stream": False,
-            "guardrails": {
-                "config_id": self.config_id,
-            },
         }
-        response = await self._guardrails_post(path="/v1/guardrail/checks", data=request_data)
-
-        if response["status"] == "blocked":
-            user_message = "Sorry I cannot do this."
-            metadata = response["rails_status"]
+        response = await self._guardrails_post(path="/v1/chat/completions", data=request_data)
 
+        # Support legacy format with explicit status field
+        if "status" in response and response["status"] == "blocked":
             return RunShieldResponse(
                 violation=SafetyViolation(
-                    user_message=user_message,
+                    user_message="Sorry I cannot do this.",
                     violation_level=ViolationLevel.ERROR,
-                    metadata=metadata,
+                    metadata=response.get("rails_status", {}),
                 )
             )
 
-        return RunShieldResponse(violation=None)
+        # 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="Sorry I cannot do this.",
+                violation_level=ViolationLevel.ERROR,
+                metadata={"reason": "Content violates safety guidelines", "response": content or "(empty)"},
+            )
+            if is_blocked
+            else None
+        )

tests/unit/providers/nvidia/test_safety.py

@@ -152,22 +152,13 @@ async def test_run_shield_allowed(nvidia_adapter, mock_guardrails_post):
 
     # Verify the Guardrails API was called correctly
     mock_guardrails_post.assert_called_once_with(
-        path="/v1/guardrail/checks",
+        path="/v1/chat/completions",
         data={
-            "model": shield_id,
+            "config_id": "self-check",
             "messages": [
                 {"role": "user", "content": "Hello, how are you?"},
                 {"role": "assistant", "content": "I'm doing well, thank you for asking!"},
             ],
-            "temperature": 1.0,
-            "top_p": 1,
-            "frequency_penalty": 0,
-            "presence_penalty": 0,
-            "max_tokens": 160,
-            "stream": False,
-            "guardrails": {
-                "config_id": "self-check",
-            },
         },
     )
 
@@ -206,22 +197,13 @@ async def test_run_shield_blocked(nvidia_adapter, mock_guardrails_post):
 
     # Verify the Guardrails API was called correctly
     mock_guardrails_post.assert_called_once_with(
-        path="/v1/guardrail/checks",
+        path="/v1/chat/completions",
         data={
-            "model": shield_id,
+            "config_id": "self-check",
             "messages": [
                 {"role": "user", "content": "Hello, how are you?"},
                 {"role": "assistant", "content": "I'm doing well, thank you for asking!"},
             ],
-            "temperature": 1.0,
-            "top_p": 1,
-            "frequency_penalty": 0,
-            "presence_penalty": 0,
-            "max_tokens": 160,
-            "stream": False,
-            "guardrails": {
-                "config_id": "self-check",
-            },
         },
     )
 
@@ -286,22 +268,13 @@ async def test_run_shield_http_error(nvidia_adapter, mock_guardrails_post):
 
     # Verify the Guardrails API was called correctly
     mock_guardrails_post.assert_called_once_with(
-        path="/v1/guardrail/checks",
+        path="/v1/chat/completions",
         data={
-            "model": shield_id,
+            "config_id": "self-check",
             "messages": [
                 {"role": "user", "content": "Hello, how are you?"},
                 {"role": "assistant", "content": "I'm doing well, thank you for asking!"},
             ],
-            "temperature": 1.0,
-            "top_p": 1,
-            "frequency_penalty": 0,
-            "presence_penalty": 0,
-            "max_tokens": 160,
-            "stream": False,
-            "guardrails": {
-                "config_id": "self-check",
-            },
         },
     )
     # Verify the exception message