From 92fbe7698bc65218927f08f92c4344394d93059b Mon Sep 17 00:00:00 2001
From: Saylee <saylee21@users.noreply.github.com>
Date: Mon, 12 Oct 2026 00:16:24 +0530
Subject: [PATCH] fix(openai): json_mode stop finish_reason after folding tool
 call

When json_mode folds a tool call into JSON content, the transform sets
finish_reason to "stop" but then overwrites it by re-reading the raw
provider finish_reason ("tool_calls"), so the choice reports
finish_reason "tool_calls" while message.tool_calls is None. Report the
finish_reason the transform already computed instead. Normal tool-call
responses keep the existing "tool_calls" correction.

Signed-off-by: Saylee <saylee21@users.noreply.github.com>
---
 .../llms/openai/chat/gpt_transformation.py    |  2 +-
 .../chat/test_openai_gpt_transformation.py    | 29 +++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/litellm/llms/openai/chat/gpt_transformation.py b/litellm/llms/openai/chat/gpt_transformation.py
index 0479ac5c36c..a52f36e732c 100644
--- a/litellm/llms/openai/chat/gpt_transformation.py
+++ b/litellm/llms/openai/chat/gpt_transformation.py
@@ -822,7 +822,7 @@ class OpenAIGPTConfig(BaseLLMModelInfo, BaseConfig):
             )
 
             translated_choice.finish_reason = map_finish_reason(
-                self._get_finish_reason(translated_message, choice["finish_reason"])
+                self._get_finish_reason(translated_message, finish_reason)
             )
             transformed_choices.append(translated_choice)
 
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 263c2f7618d..6573fc1323f 100644
--- a/tests/unit/llms/openai/chat/test_openai_gpt_transformation.py
+++ b/tests/unit/llms/openai/chat/test_openai_gpt_transformation.py
@@ -2215,3 +2215,32 @@ async def test_chat_sends_a_breakpoint_by_the_deployments_own_flag_not_a_sibling
         "opted-in": True,
         "flagless": False,
     }
+
+
+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."""
+    choice = [
+        {
+            "finish_reason": "tool_calls",
+            "index": 0,
+            "logprobs": None,
+            "message": {
+                "content": None,
+                "role": "assistant",
+                "tool_calls": [
+                    {
+                        "id": "call_1",
+                        "type": "function",
+                        "function": {"name": "json_tool_call", "arguments": '{"a": 1}'},
+                    }
+                ],
+            },
+        }
+    ]
+
+    out = OpenAIGPTConfig()._transform_choices(choices=choice, json_mode=True)
+
+    assert out[0].message.content == '{"a": 1}'
+    assert out[0].message.tool_calls is None
+    assert out[0].finish_reason == "stop"