diff --git a/litellm/llms/bedrock_mantle/responses/transformation.py b/litellm/llms/bedrock_mantle/responses/transformation.py
index 4710577aea0..53a3e634adf 100644
--- a/litellm/llms/bedrock_mantle/responses/transformation.py
+++ b/litellm/llms/bedrock_mantle/responses/transformation.py
@@ -214,11 +214,15 @@ class BedrockMantleResponsesAPIConfig(BedrockMantleAuthMixin, OpenAIResponsesAPI
             summary,
             sorted(_BEDROCK_MANTLE_OPENAI_PATH_SUPPORTED_REASONING_SUMMARIES),
         )
-        stripped: Final = {key: value for key, value in reasoning.items() if key != "summary"}
+        stripped: Final = {  # mutable-ok: map_openai_params contract returns a plain dict
+            key: value for key, value in reasoning.items() if key != "summary"
+        }
         return (
-            {**params, "reasoning": stripped}
+            {**params, "reasoning": stripped}  # mutable-ok: map_openai_params contract returns a plain dict
             if stripped
-            else {key: value for key, value in params.items() if key != "reasoning"}
+            else {  # mutable-ok: map_openai_params contract returns a plain dict
+                key: value for key, value in params.items() if key != "reasoning"
+            }
         )
 
     def transform_responses_api_request(