fix(xai): treat an explicit empty web_search filters object as unrestricted

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/llms/xai/responses/transformation.py

@@ -3,6 +3,7 @@ from types import MappingProxyType
 from typing import TYPE_CHECKING, Any, Final
 
 import httpx
+from pydantic import TypeAdapter
 
 import litellm
 from litellm._logging import verbose_logger
@@ -32,6 +33,8 @@ if TYPE_CHECKING:
 else:
     LiteLLMLoggingObj = Any
 
+_STR_MAPPING_ADAPTER: Final = TypeAdapter(Mapping[str, object])
+
 
 def _usage_restated_from_xai_ticks(usage: ResponseAPIUsage | None) -> ResponseAPIUsage | None:
     reported_cost: Final = xai_reported_cost_in_usd(getattr(usage, "cost_in_usd_ticks", None))
@@ -91,7 +94,10 @@ class XAIResponsesAPIConfig(OpenAIResponsesAPIConfig):
                 "XAI does not support 'search_context_size' parameter. Removing it from web_search tool."
             )
 
-        domains: Final = tool.get("filters") or tool
+        nested_filters: Final = tool.get("filters")
+        domains: Final = (
+            _STR_MAPPING_ADAPTER.validate_python(nested_filters) if isinstance(nested_filters, Mapping) else tool
+        )
         filters: Final = {key: domains[key] for key in ("allowed_domains", "excluded_domains") if key in domains}
 
         if filters:

tests/test_litellm/llms/xai/responses/test_xai_responses_transformation.py

@@ -164,6 +164,22 @@ class TestXAIResponsesAPITransformation:
 
         assert result["tools"][0]["filters"] == {"allowed_domains": ["nested.com"]}
 
+    def test_web_search_empty_nested_filters_win_over_flat(self):
+        """An explicit empty 'filters' object means unrestricted search, even when stale flat fields are present"""
+        config = XAIResponsesAPIConfig()
+
+        params = ResponsesAPIOptionalRequestParams(
+            tools=[{"type": "web_search", "allowed_domains": ["flat.com"], "filters": {}}]
+        )
+
+        result = config.map_openai_params(
+            response_api_optional_params=params,
+            model="grok-4-1-fast",
+            drop_params=False,
+        )
+
+        assert result["tools"][0] == {"type": "web_search"}
+
     def test_web_search_search_context_size_removed(self):
         """Test that search_context_size is removed from web_search tools"""
         config = XAIResponsesAPIConfig()