fix(bedrock_mantle): hoist Codex additional_tools input items to top-level tools

litellm/llms/bedrock_mantle/responses/transformation.py

@@ -25,7 +25,10 @@
 )
 from litellm.llms.openai.responses.transformation import OpenAIResponsesAPIConfig
 from litellm.secret_managers.main import get_secret_str
-from litellm.types.llms.openai import ResponsesAPIOptionalRequestParams
+from litellm.types.llms.openai import (
+    ResponseInputParam,
+    ResponsesAPIOptionalRequestParams,
+)
 from litellm.types.router import GenericLiteLLMParams
 from litellm.types.utils import LlmProviders
 
@@ -42,6 +45,8 @@
 # Per Bedrock Mantle Responses API validation errors.
 _BEDROCK_MANTLE_SUPPORTED_RESPONSE_TOOL_TYPES = frozenset({"function", "mcp", "custom", "namespace", "tool_search"})
 
+_CODEX_ADDITIONAL_TOOLS_INPUT_ITEM_TYPE = "additional_tools"
+
 
 class BedrockMantleResponsesAPIConfig(BedrockMantleAuthMixin, OpenAIResponsesAPIConfig):
     def __init__(
@@ -116,6 +121,70 @@ def _filter_unsupported_tools(tools: List[Any]) -> List[Any]:
 
         return kept
 
+    def transform_responses_api_request(
+        self,
+        model: str,
+        input: "str | ResponseInputParam",
+        response_api_optional_request_params: dict,
+        litellm_params: GenericLiteLLMParams,
+        headers: dict,
+    ) -> dict:
+        remaining_input, hoisted_tools = self._hoist_codex_additional_tools(input)
+        request_params = (
+            {
+                **response_api_optional_request_params,
+                "tools": [
+                    *(response_api_optional_request_params.get("tools") or []),
+                    *hoisted_tools,
+                ],
+            }
+            if hoisted_tools
+            else response_api_optional_request_params
+        )
+        return super().transform_responses_api_request(
+            model=model,
+            input=remaining_input,
+            response_api_optional_request_params=request_params,
+            litellm_params=litellm_params,
+            headers=headers,
+        )
+
+    @staticmethod
+    def _is_codex_additional_tools_item(item: Any) -> bool:
+        return isinstance(item, dict) and item.get("type") == _CODEX_ADDITIONAL_TOOLS_INPUT_ITEM_TYPE
+
+    @staticmethod
+    def _tools_of_additional_tools_item(item: "dict[str, Any]") -> "list[Any]":
+        tools = item.get("tools")
+        return tools if isinstance(tools, list) else []
+
+    @classmethod
+    def _hoist_codex_additional_tools(
+        cls,
+        input: "str | ResponseInputParam",
+    ) -> "tuple[str | ResponseInputParam, list[Any]]":
+        """Codex's "responses lite" wire mode ships tool definitions inside
+        `input` as {"type": "additional_tools", "role": "developer",
+        "tools": [...]} items. api.openai.com accepts that item type; Mantle
+        rejects the whole request with 400 "Invalid 'input': value did not
+        match any expected variant" but accepts the same tools at the top
+        level, so move them there and strip the items from `input`.
+        """
+        if not isinstance(input, list):
+            return input, []
+        additional_tools_items = [item for item in input if cls._is_codex_additional_tools_item(item)]
+        if not additional_tools_items:
+            return input, []
+        remaining_input = [item for item in input if not cls._is_codex_additional_tools_item(item)]
+        hoisted_tools = [tool for item in additional_tools_items for tool in cls._tools_of_additional_tools_item(item)]
+        verbose_logger.debug(
+            "Bedrock Mantle Responses API: hoisting %d tool(s) out of %d 'additional_tools' input item(s) "
+            "into the top-level tools param (Mantle rejects that input item type).",
+            len(hoisted_tools),
+            len(additional_tools_items),
+        )
+        return remaining_input, cls._filter_unsupported_tools(hoisted_tools)
+
     def map_openai_params(
         self,
         response_api_optional_params: ResponsesAPIOptionalRequestParams,

tests/test_litellm/llms/bedrock_mantle/test_bedrock_mantle_responses_transformation.py

@@ -373,6 +373,144 @@ def test_dropped_tools_are_logged_at_warning_level(self):
         assert "web_search" in str(mock_warning.call_args)
 
 
+class TestBedrockMantleCodexAdditionalTools:
+    """Codex CLI's "responses lite" wire mode ships tool definitions inside
+    `input` as {"type": "additional_tools", "role": "developer", "tools": [...]}
+    items instead of the top-level `tools` param. api.openai.com accepts that
+    item; Mantle 400s the whole request with "Invalid 'input': value did not
+    match any expected variant" but accepts the same tools at the top level
+    (verified against bedrock-mantle.us-east-2.api.aws with openai.gpt-5.6-sol),
+    so the config must hoist them."""
+
+    _USER_MESSAGE = {
+        "type": "message",
+        "role": "user",
+        "content": [{"type": "input_text", "text": "Say hi in one word."}],
+    }
+    _DEVELOPER_MESSAGE = {
+        "type": "message",
+        "role": "developer",
+        "content": [{"type": "input_text", "text": "You are Codex."}],
+    }
+    _CODEX_TOOLS = [
+        {"type": "custom", "name": "exec", "format": {"type": "grammar", "syntax": "lark", "definition": "start: X"}},
+        {"type": "function", "name": "wait", "parameters": {"type": "object"}},
+        {"type": "namespace", "name": "collaboration", "tools": [{"type": "function", "name": "spawn_agent"}]},
+    ]
+
+    def _transform(self, input, params=None):
+        cfg = BedrockMantleResponsesAPIConfig()
+        return cfg.transform_responses_api_request(
+            model="openai.gpt-5.6-sol",
+            input=input,
+            response_api_optional_request_params=params if params is not None else {},
+            litellm_params=GenericLiteLLMParams(),
+            headers={},
+        )
+
+    def test_additional_tools_item_hoisted_to_top_level_tools(self):
+        body = self._transform(
+            input=[
+                {"type": "additional_tools", "role": "developer", "tools": self._CODEX_TOOLS},
+                self._DEVELOPER_MESSAGE,
+                self._USER_MESSAGE,
+            ]
+        )
+        assert body["input"] == [self._DEVELOPER_MESSAGE, self._USER_MESSAGE]
+        assert body["tools"] == self._CODEX_TOOLS
+
+    def test_hoisted_tools_append_after_existing_tools(self):
+        existing_tool = {"type": "function", "name": "preexisting"}
+        body = self._transform(
+            input=[
+                {"type": "additional_tools", "role": "developer", "tools": self._CODEX_TOOLS},
+                self._USER_MESSAGE,
+            ],
+            params={"tools": [existing_tool]},
+        )
+        assert body["tools"] == [existing_tool, *self._CODEX_TOOLS]
+
+    def test_unsupported_hoisted_tool_types_are_dropped(self):
+        body = self._transform(
+            input=[
+                {
+                    "type": "additional_tools",
+                    "role": "developer",
+                    "tools": [
+                        {"type": "web_search"},
+                        {"type": "function", "name": "wait"},
+                    ],
+                },
+                self._USER_MESSAGE,
+            ]
+        )
+        assert body["tools"] == [{"type": "function", "name": "wait"}]
+
+    def test_item_stripped_even_when_no_hoisted_tool_survives(self):
+        body = self._transform(
+            input=[
+                {"type": "additional_tools", "role": "developer", "tools": [{"type": "web_search"}]},
+                self._USER_MESSAGE,
+            ]
+        )
+        assert body["input"] == [self._USER_MESSAGE]
+        assert "tools" not in body
+
+    def test_multiple_additional_tools_items_merge_in_order(self):
+        first = {"type": "function", "name": "first"}
+        second = {"type": "function", "name": "second"}
+        body = self._transform(
+            input=[
+                {"type": "additional_tools", "role": "developer", "tools": [first]},
+                self._USER_MESSAGE,
+                {"type": "additional_tools", "role": "developer", "tools": [second]},
+            ]
+        )
+        assert body["input"] == [self._USER_MESSAGE]
+        assert body["tools"] == [first, second]
+
+    def test_string_input_passes_through(self):
+        body = self._transform(input="hello")
+        assert body["input"] == "hello"
+        assert "tools" not in body
+
+    def test_input_without_additional_tools_is_unchanged(self):
+        codex_agentic_items = [
+            self._USER_MESSAGE,
+            {"type": "reasoning", "summary": [], "encrypted_content": "gAAAA=="},
+            {"type": "function_call", "name": "wait", "arguments": "{}", "call_id": "call_1"},
+            {"type": "function_call_output", "call_id": "call_1", "output": "done"},
+        ]
+        body = self._transform(input=list(codex_agentic_items))
+        assert body["input"] == codex_agentic_items
+        assert "tools" not in body
+
+    def test_malformed_additional_tools_item_without_tools_list_is_stripped(self):
+        body = self._transform(
+            input=[
+                {"type": "additional_tools", "role": "developer"},
+                self._USER_MESSAGE,
+            ]
+        )
+        assert body["input"] == [self._USER_MESSAGE]
+        assert "tools" not in body
+
+    def test_hoist_is_logged_at_debug_level(self):
+        from unittest.mock import patch
+
+        with patch(
+            "litellm.llms.bedrock_mantle.responses.transformation.verbose_logger.debug"
+        ) as mock_debug:
+            self._transform(
+                input=[
+                    {"type": "additional_tools", "role": "developer", "tools": self._CODEX_TOOLS},
+                    self._USER_MESSAGE,
+                ]
+            )
+        assert mock_debug.call_count == 1
+        assert "additional_tools" in str(mock_debug.call_args)
+
+
 class TestBedrockMantleResponsesRegistry:
     def test_registry_returns_config_for_gpt_5_5(self, local_cost_map):
         # gpt-5.x advertises /v1/responses in supported_endpoints (capability)