fix(bedrock_mantle): gate reasoning.summary on the OpenAI Responses path

Mantle's /openai/v1/responses rejects reasoning.summary values other than "auto" with 400 unsupported_parameter. Drop it with a warning under drop_params, otherwise raise UnsupportedParamsError naming the remedy.

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

litellm/llms/bedrock_mantle/responses/transformation.py

@@ -56,6 +56,7 @@ _BEDROCK_MANTLE_SUPPORTED_RESPONSE_TOOL_TYPES: Final = frozenset(
 )
 
 _BEDROCK_MANTLE_SUPPORTED_SERVICE_TIERS: Final = frozenset({"auto", "default"})
+_BEDROCK_MANTLE_OPENAI_PATH_SUPPORTED_REASONING_SUMMARIES: Final = frozenset({"auto"})
 
 _CODEX_ADDITIONAL_TOOLS_INPUT_ITEM_TYPE: Final = "additional_tools"
 
@@ -187,6 +188,35 @@ class BedrockMantleResponsesAPIConfig(BedrockMantleAuthMixin, OpenAIResponsesAPI
         )
         return {key: value for key, value in params.items() if key != "service_tier"}
 
+    def _handle_unsupported_reasoning_summary(self, params: dict, model: str, drop_params: bool) -> dict:
+        reasoning: Final = params.get("reasoning")
+        if not self.use_openai_path or not isinstance(reasoning, dict):
+            return params
+        summary: Final = reasoning.get("summary")
+        if summary is None or summary in _BEDROCK_MANTLE_OPENAI_PATH_SUPPORTED_REASONING_SUMMARIES:
+            return params
+        if not drop_params:
+            raise litellm.utils.UnsupportedParamsError(
+                status_code=400,
+                message=(
+                    f"bedrock_mantle does not support reasoning.summary={summary!r} for {model!r}; the Bedrock Mantle "
+                    "OpenAI Responses path only accepts 'auto'. Set `drop_params: true` (litellm_settings or this "
+                    'deployment\'s litellm_params) to have LiteLLM drop it, or set `model_reasoning_summary = "auto"` '
+                    "in the client (Codex CLI: ~/.codex/config.toml)."
+                ),
+            )
+        verbose_logger.warning(
+            "Bedrock Mantle Responses API: dropping unsupported reasoning.summary %r (supported: %s).",
+            summary,
+            sorted(_BEDROCK_MANTLE_OPENAI_PATH_SUPPORTED_REASONING_SUMMARIES),
+        )
+        stripped: Final = {key: value for key, value in reasoning.items() if key != "summary"}
+        return (
+            {**params, "reasoning": stripped}
+            if stripped
+            else {key: value for key, value in params.items() if key != "reasoning"}
+        )
+
     def transform_responses_api_request(
         self,
         model: str,
@@ -343,12 +373,16 @@ class BedrockMantleResponsesAPIConfig(BedrockMantleAuthMixin, OpenAIResponsesAPI
         model: str,
         drop_params: bool,
     ) -> dict:
-        params: Final = self._handle_unsupported_service_tier(
-            super().map_openai_params(
-                response_api_optional_params=response_api_optional_params,
-                model=model,
+        params: Final = self._handle_unsupported_reasoning_summary(
+            self._handle_unsupported_service_tier(
+                super().map_openai_params(
+                    response_api_optional_params=response_api_optional_params,
+                    model=model,
+                    drop_params=drop_params,
+                ),
                 drop_params=drop_params,
             ),
+            model=model,
             drop_params=drop_params,
         )
 

tests/test_litellm/llms/bedrock_mantle/test_bedrock_mantle_responses_transformation.py

@@ -539,6 +539,81 @@ class TestBedrockMantleServiceTier:
         assert "priority" in str(mock_warning.call_args)
 
 
+class TestBedrockMantleReasoningSummary:
+    @pytest.mark.parametrize("summary", ["concise", "detailed"])
+    def test_unsupported_reasoning_summary_dropped_when_drop_params_true(self, summary):
+        cfg = BedrockMantleResponsesAPIConfig()
+        params = cfg.map_openai_params(
+            response_api_optional_params={"reasoning": {"effort": "medium", "summary": summary}},
+            model="openai.gpt-5.6-sol",
+            drop_params=True,
+        )
+        assert params["reasoning"] == {"effort": "medium"}
+
+    def test_reasoning_summary_only_field_drops_reasoning(self):
+        cfg = BedrockMantleResponsesAPIConfig()
+        params = cfg.map_openai_params(
+            response_api_optional_params={"reasoning": {"summary": "detailed"}},
+            model="openai.gpt-5.6-sol",
+            drop_params=True,
+        )
+        assert "reasoning" not in params
+
+    @pytest.mark.parametrize("summary", ["concise", "detailed"])
+    def test_unsupported_reasoning_summary_raises_when_drop_params_false(self, summary):
+        cfg = BedrockMantleResponsesAPIConfig()
+        with pytest.raises(litellm.UnsupportedParamsError) as excinfo:
+            cfg.map_openai_params(
+                response_api_optional_params={"reasoning": {"effort": "medium", "summary": summary}},
+                model="openai.gpt-5.6-sol",
+                drop_params=False,
+            )
+        assert summary in str(excinfo.value)
+        assert "reasoning.summary" in str(excinfo.value)
+        assert "drop_params" in str(excinfo.value)
+
+    @pytest.mark.parametrize("drop_params", [True, False])
+    def test_supported_reasoning_summary_kept(self, drop_params):
+        cfg = BedrockMantleResponsesAPIConfig()
+        params = cfg.map_openai_params(
+            response_api_optional_params={"reasoning": {"effort": "medium", "summary": "auto"}},
+            model="openai.gpt-5.6-sol",
+            drop_params=drop_params,
+        )
+        assert params["reasoning"] == {"effort": "medium", "summary": "auto"}
+
+    def test_reasoning_summary_kept_on_standard_path(self):
+        cfg = BedrockMantleResponsesAPIConfig(use_openai_path=False)
+        params = cfg.map_openai_params(
+            response_api_optional_params={"reasoning": {"effort": "medium", "summary": "detailed"}},
+            model="openai.gpt-oss-120b",
+            drop_params=False,
+        )
+        assert params["reasoning"] == {"effort": "medium", "summary": "detailed"}
+
+    def test_absent_reasoning_untouched(self):
+        cfg = BedrockMantleResponsesAPIConfig()
+        params = cfg.map_openai_params(
+            response_api_optional_params={"stream": True},
+            model="openai.gpt-5.6-sol",
+            drop_params=False,
+        )
+        assert params == {"stream": True}
+
+    def test_drop_logged_at_warning_level(self):
+        from unittest.mock import patch
+
+        cfg = BedrockMantleResponsesAPIConfig()
+        with patch("litellm.llms.bedrock_mantle.responses.transformation.verbose_logger.warning") as mock_warning:
+            cfg.map_openai_params(
+                response_api_optional_params={"reasoning": {"effort": "medium", "summary": "detailed"}},
+                model="openai.gpt-5.6-sol",
+                drop_params=True,
+            )
+        assert mock_warning.call_count == 1
+        assert "detailed" in str(mock_warning.call_args)
+
+
 class TestBedrockMantleCodexRequestEndToEnd:
     def test_codex_priority_tier_request_becomes_mantle_acceptable(self):
         cfg = BedrockMantleResponsesAPIConfig()