fix: handle string input in Azure guardrails for Responses API

Address Greptile review — the Responses API allows input as either:
- A list of message objects: [{"role": "user", "content": "..."}]
- A plain string: "What is the capital of France?"

The previous fix passed data["input"] directly to get_user_prompt(),
which would crash with AttributeError when input is a string (iterating
over characters instead of message dicts).

Now uses isinstance checks to handle both formats: wrap strings into
a message object, pass lists directly.

Co-Authored-By: Claude <noreply@anthropic.com>

litellm/proxy/guardrails/guardrail_hooks/azure/prompt_shield.py

@@ -134,7 +134,14 @@ class AzureContentSafetyPromptShieldGuardrail(AzureGuardrailBase, CustomGuardrai
             "Azure Prompt Shield: Running pre-call prompt scan, on call_type: %s",
             call_type,
         )
-        new_messages: Optional[List[AllMessageValues]] = data.get("messages") or data.get("input")
+        new_messages: Optional[List[AllMessageValues]] = data.get("messages")
+        if new_messages is None:
+            # Responses API uses "input" instead of "messages"
+            input_data = data.get("input")
+            if isinstance(input_data, str):
+                new_messages = [{"role": "user", "content": input_data}]
+            elif isinstance(input_data, list):
+                new_messages = input_data
         if new_messages is None:
             verbose_proxy_logger.warning(
                 "Azure Prompt Shield: not running guardrail. No messages in data"

litellm/proxy/guardrails/guardrail_hooks/azure/text_moderation.py

@@ -227,7 +227,14 @@ class AzureContentSafetyTextModerationGuardrail(AzureGuardrailBase, CustomGuardr
             "Azure Text Moderation: Running pre-call prompt scan, on call_type: %s",
             call_type,
         )
-        new_messages: Optional[List[AllMessageValues]] = data.get("messages") or data.get("input")
+        new_messages: Optional[List[AllMessageValues]] = data.get("messages")
+        if new_messages is None:
+            # Responses API uses "input" instead of "messages"
+            input_data = data.get("input")
+            if isinstance(input_data, str):
+                new_messages = [{"role": "user", "content": input_data}]
+            elif isinstance(input_data, list):
+                new_messages = input_data
         if new_messages is None:
             verbose_proxy_logger.warning(
                 "Azure Text Moderation: not running guardrail. No messages in data"