From 66a11a6287f6c63bca90f9de82e2905824deeda2 Mon Sep 17 00:00:00 2001
From: mateo-berri <277851410+mateo-berri@users.noreply.github.com>
Date: Wed, 28 Oct 2026 20:49:59 -0700
Subject: [PATCH] fix(bedrock_mantle): map the gpt-oss Responses API overflow
 wording too

Mantle's /v1/responses words gpt-oss overflow as "The engine prompt length N
exceeds the max_model_len M", so a streamed /v1/responses overflow still ended in
a response.failed carrying a plain BadRequestError. Match that wording as well.
---
 .../exception_mapping_utils.py                |  7 ++++---
 .../test_exception_mapping_utils.py           | 21 +++++++++++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/litellm/litellm_core_utils/exception_mapping_utils.py b/litellm/litellm_core_utils/exception_mapping_utils.py
index c37db350c6d..6aac1918993 100644
--- a/litellm/litellm_core_utils/exception_mapping_utils.py
+++ b/litellm/litellm_core_utils/exception_mapping_utils.py
@@ -895,6 +895,7 @@ def _map_openai_like_exception(
 _BEDROCK_MANTLE_CONTEXT_WINDOW_PATTERNS: Final = (
     re.compile(r"prompt tokens \((\d+)\) exceed model maximum \((\d+)\)"),
     re.compile(r"Input length \((\d+)\) exceeds model\\?'s maximum context length \((\d+)\)"),
+    re.compile(r"The engine prompt length (\d+) exceeds the max_model_len (\d+)"),
 )
 _BEDROCK_MANTLE_CONTEXT_LENGTH_EXCEEDED_CODE_PATTERN: Final = re.compile(
     r"""\\?["']code\\?["']\s*:\s*\\?["']context_length_exceeded\\?["']"""
@@ -916,9 +917,9 @@ def _bedrock_mantle_context_window_response(original_exception: _ProviderHTTPExc
 def _get_bedrock_mantle_context_window_message(error_str: str) -> str | None:
     """
     Mantle reports context overflow as a validation_error carrying the token counts (worded
-    differently for gpt-oss), or as OpenAI's context_length_exceeded code, either in a 400 body
-    or in a streamed error event with no error type. Clients such as Claude Code only treat
-    "prompt is too long" as overflow (litellm/litellm#36546).
+    differently for gpt-oss, and again on its Responses API), or as OpenAI's context_length_exceeded
+    code, either in a 400 body or in a streamed error event with no error type. Clients such as
+    Claude Code only treat "prompt is too long" as overflow (litellm/litellm#36546).
     """
     matches: Final = (pattern.search(error_str) for pattern in _BEDROCK_MANTLE_CONTEXT_WINDOW_PATTERNS)
     match: Final = next((found for found in matches if found is not None), None)
diff --git a/tests/unit/litellm_core_utils/test_exception_mapping_utils.py b/tests/unit/litellm_core_utils/test_exception_mapping_utils.py
index 1a96a090f3b..4ac7c644cda 100644
--- a/tests/unit/litellm_core_utils/test_exception_mapping_utils.py
+++ b/tests/unit/litellm_core_utils/test_exception_mapping_utils.py
@@ -1538,6 +1538,27 @@ def test_bedrock_mantle_gpt_oss_input_length_overflow_maps_to_context_window_exc
     assert "prompt is too long: 360068 tokens > 131072 maximum" in excinfo.value.message
 
 
+def test_bedrock_mantle_gpt_oss_streamed_responses_overflow_event_maps_to_context_window_exceeded():
+    from litellm.responses.streaming_iterator import map_stream_error_to_exception
+
+    mapped_exception = map_stream_error_to_exception(
+        {
+            "code": "invalid_prompt",
+            "message": (
+                'ErrorEvent { error: APIError { type: "invalid_request_error", code: Some(400), message: '
+                '"The engine prompt length 165072 exceeds the max_model_len 131072. Please reduce prompt.", '
+                'param: Some("input") } }'
+            ),
+        },
+        model="openai.gpt-oss-20b",
+        custom_llm_provider="bedrock_mantle",
+    )
+
+    assert isinstance(mapped_exception, litellm.ContextWindowExceededError)
+    assert mapped_exception.status_code == 400
+    assert "prompt is too long: 165072 tokens > 131072 maximum" in mapped_exception.message
+
+
 def test_bedrock_mantle_openai_envelope_context_overflow_maps_to_context_window_exceeded():
     from litellm.llms.base_llm.chat.transformation import BaseLLMException