fix(logging): redact system_prompt when message logging is off

Include system_prompt in _redact_standard_logging_object and
CustomLogger.redact_standard_logging_payload_from_model_call_details
so list-form system blocks do not bypass turn_off_message_logging.

Also remove new docstring/comments flagged in PR review.

litellm/integrations/custom_logger.py

@@ -885,6 +885,12 @@ class CustomLogger:  # https://docs.litellm.ai/docs/observability/custom_callbac
             if "messages" not in (excluded_fields or []) and standard_logging_object_copy.get("messages") is not None:
                 standard_logging_object_copy["messages"] = [Message(content=redacted_str).model_dump()]
 
+            if (
+                "system_prompt" not in (excluded_fields or [])
+                and standard_logging_object_copy.get("system_prompt") is not None
+            ):
+                standard_logging_object_copy["system_prompt"] = redacted_str
+
             if "response" not in (excluded_fields or []) and standard_logging_object_copy.get("response") is not None:
                 response = standard_logging_object_copy["response"]
                 # Check if this is a ResponsesAPIResponse (has "output" field)

litellm/litellm_core_utils/litellm_logging.py

@@ -4557,13 +4557,6 @@ class StandardLoggingPayloadSetup:
 
     @staticmethod
     def get_system_prompt_from_kwargs(kwargs: Optional[Dict] = None) -> Optional[Union[str, list, dict]]:
-        """
-        Return the system prompt kwargs as sent by the client, without reshaping.
-
-        Coalesces the kwarg names used across call paths (Vertex Gemini, Responses API,
-        Anthropic Messages). Uses `is not None` checks so falsy values like [] do not
-        fall through to a different kwarg.
-        """
         if kwargs is None:
             return None
 

litellm/litellm_core_utils/redact_messages.py

@@ -169,6 +169,9 @@ def _redact_standard_logging_object(model_call_details: dict):
     if standard_logging_object.get("messages") is not None:
         standard_logging_object["messages"] = [{"role": "user", "content": redacted_str}]
 
+    if standard_logging_object.get("system_prompt") is not None:
+        standard_logging_object["system_prompt"] = redacted_str
+
     response = standard_logging_object.get("response")
     if response is not None:
         if isinstance(response, dict) and "output" in response:

tests/logging_callback_tests/test_standard_logging_payload_excluded_fields.py

@@ -62,6 +62,7 @@ def create_sample_standard_logging_payload() -> Dict:
         "requester_ip_address": None,
         "user_agent": None,
         "messages": [{"role": "user", "content": "Hello, this is sensitive data!"}],
+        "system_prompt": [{"type": "text", "text": "sensitive system prompt"}],
         "response": {
             "choices": [{"message": {"content": "This is a sensitive response!"}}]
         },
@@ -226,6 +227,7 @@ class TestStandardLoggingPayloadExcludedFields:
         assert (
             result["standard_logging_object"]["messages"][0]["content"] == redacted_str
         )
+        assert result["standard_logging_object"]["system_prompt"] == redacted_str
         assert (
             result["standard_logging_object"]["response"]["choices"][0]["message"][
                 "content"

tests/test_litellm/litellm_core_utils/test_litellm_logging.py

@@ -2166,7 +2166,6 @@ def test_append_system_prompt_messages():
 def test_get_system_prompt_from_kwargs():
     from litellm.litellm_core_utils.litellm_logging import StandardLoggingPayloadSetup
 
-    # Anthropic Messages list-form system blocks
     system_blocks = [
         {"type": "text", "text": "SHAPE-SECRET", "cache_control": {"type": "ephemeral"}},
     ]
@@ -2175,22 +2174,18 @@ def test_get_system_prompt_from_kwargs():
     )
     assert result == system_blocks
 
-    # String system kwarg
     result = StandardLoggingPayloadSetup.get_system_prompt_from_kwargs(kwargs={"system": "Be helpful"})
     assert result == "Be helpful"
 
-    # Responses API instructions
     result = StandardLoggingPayloadSetup.get_system_prompt_from_kwargs(kwargs={"instructions": "Follow policy"})
     assert result == "Follow policy"
 
-    # Vertex Gemini system_instructions
     gemini_system = [{"role": "system", "content": "Be concise."}]
     result = StandardLoggingPayloadSetup.get_system_prompt_from_kwargs(
         kwargs={"system_instructions": gemini_system}
     )
     assert result == gemini_system
 
-    # system_instructions wins over instructions and system
     result = StandardLoggingPayloadSetup.get_system_prompt_from_kwargs(
         kwargs={
             "system_instructions": "From Gemini",
@@ -2200,19 +2195,16 @@ def test_get_system_prompt_from_kwargs():
     )
     assert result == "From Gemini"
 
-    # Empty list should not fall through to instructions
     result = StandardLoggingPayloadSetup.get_system_prompt_from_kwargs(
         kwargs={"system_instructions": [], "instructions": "From Responses"}
     )
     assert result == []
 
-    # No system kwargs
     assert StandardLoggingPayloadSetup.get_system_prompt_from_kwargs(kwargs={}) is None
     assert StandardLoggingPayloadSetup.get_system_prompt_from_kwargs(kwargs=None) is None
 
 
 def test_get_standard_logging_object_payload_includes_system_prompt_for_list_system(logging_obj):
-    """List-form Anthropic system blocks must appear on the payload without mutating messages."""
     import datetime
 
     from litellm.litellm_core_utils.litellm_logging import get_standard_logging_object_payload

tests/test_litellm/litellm_core_utils/test_redact_messages.py

@@ -14,6 +14,7 @@ from litellm.integrations.custom_logger import CustomLogger
 from litellm.litellm_core_utils.redact_messages import (
     _redact_responses_api_output,
     perform_redaction,
+    redact_message_input_output_from_logging,
     redact_streaming_responses_for_custom_logger,
     should_redact_message_logging,
 )
@@ -181,6 +182,9 @@ class TestPerformRedaction:
             "input": "sensitive input",
             "standard_logging_object": {
                 "messages": [{"role": "user", "content": "sensitive input"}],
+                "system_prompt": [
+                    {"type": "text", "text": "SHAPE-SECRET", "cache_control": {"type": "ephemeral"}},
+                ],
                 "response": {
                     "output": [
                         {"text": "top-level text"},
@@ -207,6 +211,7 @@ class TestPerformRedaction:
         ]
         assert details["prompt"] == ""
         assert details["input"] == ""
+        assert details["standard_logging_object"]["system_prompt"] == "redacted-by-litellm"
 
         logged_response = details["standard_logging_object"]["response"]
         assert logged_response["usage"] == {"total_tokens": 1}
@@ -720,3 +725,47 @@ class TestRedactStreamingResponsesForCustomLogger:
 
         assert result_details is model_call_details
         assert response_obj.choices[0].message.content == "secret content"
+
+
+class TestSystemPromptRedaction:
+    REDACTED = "redacted-by-litellm"
+    SYSTEM_PROMPT = [{"type": "text", "text": "SHAPE-SECRET"}]
+
+    def _details_with_system_prompt(self, **extra):
+        details = {
+            "messages": [{"role": "user", "content": "hi"}],
+            "standard_logging_object": {
+                "messages": [{"role": "user", "content": "hi"}],
+                "system_prompt": self.SYSTEM_PROMPT,
+                "response": {"choices": [{"message": {"content": "secret"}}]},
+            },
+            "litellm_params": {"metadata": {}},
+        }
+        details.update(extra)
+        return details
+
+    def test_global_turn_off_message_logging_redacts_system_prompt(self):
+        litellm.turn_off_message_logging = True
+        details = self._details_with_system_prompt()
+
+        redact_message_input_output_from_logging(details, result=None)
+
+        assert details["standard_logging_object"]["system_prompt"] == self.REDACTED
+
+    def test_request_level_dynamic_param_redacts_system_prompt(self):
+        details = self._details_with_system_prompt(
+            standard_callback_dynamic_params={"turn_off_message_logging": True}
+        )
+
+        redact_message_input_output_from_logging(details, result=None)
+
+        assert details["standard_logging_object"]["system_prompt"] == self.REDACTED
+
+    def test_per_callback_turn_off_message_logging_redacts_system_prompt(self):
+        details = self._details_with_system_prompt()
+        logger = CustomLogger(turn_off_message_logging=True)
+
+        result = logger.redact_standard_logging_payload_from_model_call_details(details)
+
+        assert result["standard_logging_object"]["system_prompt"] == self.REDACTED
+        assert details["standard_logging_object"]["system_prompt"] == self.SYSTEM_PROMPT