From 5e65f314ebc3883823d59901b6f6ee864141015a Mon Sep 17 00:00:00 2001 From: Saylee Date: Mon, 12 Oct 2026 22:40:05 +0530 Subject: [PATCH] fix(openai): only fold tool-call finish reasons to stop in json_mode The previous change folded every json_mode tool call to finish_reason "stop", which rewrote a provider "length" reason to "stop" and hid truncated output from callers. Map only "tool_calls" and "function_call" to "stop" and pass every other reason through, and parametrize the regression test over tool_calls, function_call, length and stop. Signed-off-by: Saylee --- .../llms/openai/chat/gpt_transformation.py | 2 +- .../chat/test_openai_gpt_transformation.py | 21 ++++++++++++++----- 2 files changed, 17 insertions(+), 6 deletions(-) diff --git a/litellm/llms/openai/chat/gpt_transformation.py b/litellm/llms/openai/chat/gpt_transformation.py index a52f36e732c..19b681f7415 100644 --- a/litellm/llms/openai/chat/gpt_transformation.py +++ b/litellm/llms/openai/chat/gpt_transformation.py @@ -793,7 +793,7 @@ class OpenAIGPTConfig(BaseLLMModelInfo, BaseConfig): json_mode_content_str: str | None = str(new_tool_calls[0]["function"].get("arguments", "")) or None if json_mode_content_str is not None: translated_message = Message(content=json_mode_content_str) - finish_reason = "stop" + finish_reason = "stop" if choice["finish_reason"] in ("tool_calls", "function_call") else choice["finish_reason"] if translated_message is None: ## get the reasoning content diff --git a/tests/unit/llms/openai/chat/test_openai_gpt_transformation.py b/tests/unit/llms/openai/chat/test_openai_gpt_transformation.py index 6573fc1323f..cb8367bc350 100644 --- a/tests/unit/llms/openai/chat/test_openai_gpt_transformation.py +++ b/tests/unit/llms/openai/chat/test_openai_gpt_transformation.py @@ -2217,12 +2217,23 @@ async def test_chat_sends_a_breakpoint_by_the_deployments_own_flag_not_a_sibling } -def test_transform_choices_json_mode_reports_stop_when_tool_call_becomes_content(): - """json_mode turns a tool call into JSON content; the choice must then report - finish_reason 'stop' instead of 'tool_calls' with no tool_calls attached.""" +@pytest.mark.parametrize( + "provider_finish_reason, expected_finish_reason", + [ + ("tool_calls", "stop"), + ("function_call", "stop"), + ("length", "length"), + ("stop", "stop"), + ], +) +def test_transform_choices_json_mode_reports_stop_only_for_tool_call_reasons( + provider_finish_reason, expected_finish_reason +): + """json_mode folds a tool call into JSON content. Only tool-call reasons become + 'stop'; a truncated ('length') or already-final reason must survive untouched.""" choice = [ { - "finish_reason": "tool_calls", + "finish_reason": provider_finish_reason, "index": 0, "logprobs": None, "message": { @@ -2243,4 +2254,4 @@ def test_transform_choices_json_mode_reports_stop_when_tool_call_becomes_content assert out[0].message.content == '{"a": 1}' assert out[0].message.tool_calls is None - assert out[0].finish_reason == "stop" + assert out[0].finish_reason == expected_finish_reason