fix(bedrock): keep converse extension params on the converse route

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

litellm/llms/bedrock/common_utils.py

@@ -890,7 +890,16 @@ def bedrock_runtime_chat_completions_enforces_response_format(model: str) -> boo
 
 
 BEDROCK_CONVERSE_ONLY_REQUEST_KEYS: Final = frozenset(
-    ("guardrailConfig", "performanceConfig", "serviceTier", "requestMetadata", "outputConfig", "thinking")
+    (
+        "guardrailConfig",
+        "performanceConfig",
+        "serviceTier",
+        "requestMetadata",
+        "outputConfig",
+        "thinking",
+        "additionalModelRequestFields",
+        "top_k",
+    )
 )
 
 
@@ -910,7 +919,8 @@ def bedrock_request_needs_converse(model: str, request_params: Mapping[str, obje
     """Whether a request on a runtime-Chat-Completions model must still be served by Converse.
 
     Converse-shaped body keys (``BEDROCK_CONVERSE_ONLY_REQUEST_KEYS``, the Anthropic-style ``thinking``
-    block included, which only Converse forwards as ``additionalModelRequestFields``) have no field on
+    block and the ``additionalModelRequestFields`` / ``top_k`` extension params included, which only Converse
+    forwards as ``additionalModelRequestFields`` and ``inferenceConfig``) have no field on
     AWS's native OpenAI surface, operator-owned request metadata is only written onto the Converse body,
     function tools (``tools`` or legacy ``functions``) on a model without
     ``supports_bedrock_runtime_chat_completions_tools_with_reasoning`` are rejected there unless

tests/unit/llms/bedrock/chat/chat_completions/test_bedrock_chat_completions_transformation.py

@@ -258,6 +258,18 @@ def test_guardrail_config_falls_back_to_converse(local_cost_map, model):
     assert BedrockModelInfo.get_bedrock_route(model, {"guardrailConfig": None}) == "chat_completions"
 
 
+@pytest.mark.parametrize("model", ["openai.gpt-oss-20b-1:0", "us.xai.grok-4.6"])
+@pytest.mark.parametrize(
+    "request_params",
+    [{"additionalModelRequestFields": {"reasoning_effort": "high"}}, {"top_k": 40}],
+    ids=["additionalModelRequestFields", "top_k"],
+)
+def test_converse_extension_params_fall_back_to_converse(local_cost_map, model, request_params):
+    assert bedrock_request_needs_converse(model, request_params) is True
+    assert BedrockModelInfo.get_bedrock_route(model, request_params) == "converse"
+    assert BedrockModelInfo.get_bedrock_route(model, {key: None for key in request_params}) == "chat_completions"
+
+
 @pytest.mark.parametrize(
     "request_params, expected_route",
     [