From 063844c1522d001cb223c2f8c312ae6f6ff048cd Mon Sep 17 00:00:00 2001
From: chaunceyjiang <chaunceyjiang@gmail.com>
Date: Tue, 3 Jun 2025 10:59:54 +0000
Subject: [PATCH 1/2] [Bugfix]: Fix the incompatibility issue with tool_choice
 'required' when Thinking is enabled

Signed-off-by: chaunceyjiang <chaunceyjiang@gmail.com>
---
 vllm/entrypoints/openai/serving_chat.py | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/vllm/entrypoints/openai/serving_chat.py b/vllm/entrypoints/openai/serving_chat.py
index ea8e187dc6b7..864ce2ac25ee 100644
--- a/vllm/entrypoints/openai/serving_chat.py
+++ b/vllm/entrypoints/openai/serving_chat.py
@@ -932,7 +932,8 @@ async def chat_completion_full_generator(
             else:
                 logprobs = None
             auto_tools_called = False
-
+            reasoning_content = None
+            content = output.text
             if self.reasoning_parser:
                 try:
                     reasoning_parser = self.reasoning_parser(tokenizer)
@@ -944,9 +945,6 @@ async def chat_completion_full_generator(
                 reasoning_content, content = (
                     reasoning_parser.extract_reasoning_content(
                         output.text, request=request))
-            else:
-                reasoning_content = None
-                content = output.text
 
             # if auto tools are not enabled, and a named tool choice using
             #   outlines is not being used
@@ -981,7 +979,7 @@ async def chat_completion_full_generator(
                 # the fields of FunctionDefinition are a superset of the
                 # tool call outputs and can be used for parsing
                 tool_calls = TypeAdapter(
-                    list[FunctionDefinition]).validate_json(output.text)
+                    list[FunctionDefinition]).validate_json(content)
                 message = ChatMessage(
                     role=role,
                     content="",

From f8cb8dfaec8ee216882747305c1586abb60c6c9c Mon Sep 17 00:00:00 2001
From: chaunceyjiang <chaunceyjiang@gmail.com>
Date: Tue, 3 Jun 2025 11:17:34 +0000
Subject: [PATCH 2/2] [Bugfix]: Fix the incompatibility issue with tool_choice
 'required' when Thinking is enabled

Signed-off-by: chaunceyjiang <chaunceyjiang@gmail.com>
---
 .../test_completion_with_function_calling.py  |  2 +-
 vllm/entrypoints/openai/serving_chat.py       | 22 +++++++++++++++----
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/tests/entrypoints/openai/test_completion_with_function_calling.py b/tests/entrypoints/openai/test_completion_with_function_calling.py
index dad76b54c5e9..dcc8918357c3 100644
--- a/tests/entrypoints/openai/test_completion_with_function_calling.py
+++ b/tests/entrypoints/openai/test_completion_with_function_calling.py
@@ -8,7 +8,7 @@
 from ...utils import RemoteOpenAIServer
 
 # any model with a chat template should work here
-MODEL_NAME = "Qwen/Qwen2.5-1.5B-Instruct"
+MODEL_NAME = "Qwen/Qwen3-0.6B"
 
 
 @pytest.fixture(scope="module")
diff --git a/vllm/entrypoints/openai/serving_chat.py b/vllm/entrypoints/openai/serving_chat.py
index 864ce2ac25ee..19659d97f642 100644
--- a/vllm/entrypoints/openai/serving_chat.py
+++ b/vllm/entrypoints/openai/serving_chat.py
@@ -319,10 +319,13 @@ def _filter_delta_text(delta_text: str,
     def extract_tool_call_required_streaming(
         self,
         previous_text: str,
-        current_text: str,
+        current_text: Optional[str],
         delta_text: str,
         function_name_returned: bool,
     ) -> tuple[Optional[DeltaMessage], bool]:
+        if current_text is None or current_text == "":
+            # if the current text is empty, we cannot parse it
+            return None, function_name_returned
         try:
             obj = partial_json_parser.loads(current_text)
         except partial_json_parser.core.exceptions.MalformedJSON:
@@ -649,10 +652,18 @@ async def chat_completion_stream_generator(
                         current_text = previous_text + delta_text
                         fn_name_returned = function_name_returned[i]
 
+                        if self.reasoning_parser:
+                            _, content = \
+                                reasoning_parser.extract_reasoning_content(
+                                    current_text,
+                                    request
+                                )
+                        else:
+                            content = current_text
                         delta_message, function_name_returned[i] = (
                             self.extract_tool_call_required_streaming(
                                 previous_text=previous_text,
-                                current_text=current_text,
+                                current_text=content,
                                 delta_text=delta_text,
                                 function_name_returned=fn_name_returned))
 
@@ -932,8 +943,7 @@ async def chat_completion_full_generator(
             else:
                 logprobs = None
             auto_tools_called = False
-            reasoning_content = None
-            content = output.text
+
             if self.reasoning_parser:
                 try:
                     reasoning_parser = self.reasoning_parser(tokenizer)
@@ -945,6 +955,9 @@ async def chat_completion_full_generator(
                 reasoning_content, content = (
                     reasoning_parser.extract_reasoning_content(
                         output.text, request=request))
+            else:
+                reasoning_content = None
+                content = output.text
 
             # if auto tools are not enabled, and a named tool choice using
             #   outlines is not being used
@@ -978,6 +991,7 @@ async def chat_completion_full_generator(
 
                 # the fields of FunctionDefinition are a superset of the
                 # tool call outputs and can be used for parsing
+                assert content is not None
                 tool_calls = TypeAdapter(
                     list[FunctionDefinition]).validate_json(content)
                 message = ChatMessage(