bugfix: Fix multiple finish_reason chunks and tool_calls finish reason check (#8417)

python/sglang/srt/entrypoints/openai/serving_chat.py

@@ -412,6 +412,8 @@ class OpenAIServingChat(OpenAIServingBase):
         is_firsts = {}
         stream_buffers = {}
         n_prev_tokens = {}
+        has_tool_calls = {}
+        finish_reasons = {}
 
         # Usage tracking
         prompt_tokens = {}
@@ -443,6 +445,10 @@ class OpenAIServingChat(OpenAIServingBase):
                 finish_reason = content["meta_info"]["finish_reason"]
                 finish_reason_type = finish_reason["type"] if finish_reason else None
 
+                # Track finish_reason for each index
+                if finish_reason_type:
+                    finish_reasons[index] = finish_reason
+
                 # First chunk with role
                 if is_firsts.get(index, True):
                     is_firsts[index] = False
@@ -450,13 +456,8 @@ class OpenAIServingChat(OpenAIServingBase):
                     choice_data = ChatCompletionResponseStreamChoice(
                         index=index,
                         delta=delta,
-                        finish_reason=finish_reason_type,
-                        matched_stop=(
-                            finish_reason["matched"]
-                            if finish_reason and "matched" in finish_reason
-                            else None
-                        ),
-                        logprobs=choice_logprobs,
+                        finish_reason=None,
+                        logprobs=None,
                     )
                     chunk = ChatCompletionStreamResponse(
                         id=content["meta_info"]["id"],
@@ -483,7 +484,7 @@ class OpenAIServingChat(OpenAIServingBase):
                         choice_data = ChatCompletionResponseStreamChoice(
                             index=index,
                             delta=DeltaMessage(reasoning_content=reasoning_text),
-                            finish_reason=finish_reason_type,
+                            finish_reason=None,
                         )
                         chunk = ChatCompletionStreamResponse(
                             id=content["meta_info"]["id"],
@@ -495,40 +496,34 @@ class OpenAIServingChat(OpenAIServingBase):
 
                 # Handle tool calls
                 if request.tool_choice != "none" and request.tools:
-                    async for (
-                        chunk,
-                        tool_call_finish_reason_type,
-                    ) in self._process_tool_call_stream(
+                    async for chunk in self._process_tool_call_stream(
                         index,
                         delta,
                         parser_dict,
                         content,
                         request,
-                        finish_reason_type,
+                        has_tool_calls,
                     ):
                         if chunk:
                             yield chunk
-                        finish_reason_type = tool_call_finish_reason_type
+
+                    # Send any remaining tool call arguments when generation finishes
+                    if finish_reason_type is not None and index in parser_dict:
+                        parser = parser_dict[index]
+                        remaining_chunk = self._check_for_unstreamed_tool_args(
+                            parser, content, request, index
+                        )
+                        if remaining_chunk:
+                            yield remaining_chunk
 
                 else:
                     # Regular content
-                    if delta or not (
-                        request.stream_options and request.stream_options.include_usage
-                    ):
+                    if delta:
                         choice_data = ChatCompletionResponseStreamChoice(
                             index=index,
                             delta=DeltaMessage(content=delta if delta else None),
-                            finish_reason=(
-                                None
-                                if request.stream_options
-                                and request.stream_options.include_usage
-                                else finish_reason_type
-                            ),
-                            matched_stop=(
-                                finish_reason["matched"]
-                                if finish_reason and "matched" in finish_reason
-                                else None
-                            ),
+                            finish_reason=None,
+                            matched_stop=None,
                             logprobs=choice_logprobs,
                         )
                         chunk = ChatCompletionStreamResponse(
@@ -539,26 +534,36 @@ class OpenAIServingChat(OpenAIServingBase):
                         )
                         yield f"data: {chunk.model_dump_json()}\n\n"
 
-            # Final chunk with finish_reason
-            finish_reason_chunk = ChatCompletionStreamResponse(
-                id=content["meta_info"]["id"],
-                created=int(time.time()),
-                choices=[
-                    ChatCompletionResponseStreamChoice(
-                        index=index,
-                        delta=DeltaMessage(),
-                        finish_reason=finish_reason_type,
-                        matched_stop=(
-                            finish_reason["matched"]
-                            if finish_reason and "matched" in finish_reason
-                            else None
-                        ),
-                    )
-                ],
-                model=request.model,
-                usage=None,
-            )
-            yield f"data: {finish_reason_chunk.model_dump_json()}\n\n"
+            # Send finish_reason chunks for each index that completed
+            for idx, finish_reason_data in finish_reasons.items():
+                finish_reason_type = finish_reason_data["type"]
+
+                # Change finish_reason to "tool_calls" if we had tool calls and stopped naturally
+                final_finish_reason = finish_reason_type
+                if has_tool_calls.get(idx, False) and finish_reason_type == "stop":
+                    final_finish_reason = "tool_calls"
+
+                finish_reason_chunk = ChatCompletionStreamResponse(
+                    id=content["meta_info"][
+                        "id"
+                    ],  # NOTE: openai uses the same chatcmpl-id for all indices
+                    created=int(time.time()),
+                    choices=[
+                        ChatCompletionResponseStreamChoice(
+                            index=idx,
+                            delta=DeltaMessage(),
+                            finish_reason=final_finish_reason,
+                            matched_stop=(
+                                finish_reason_data["matched"]
+                                if "matched" in finish_reason_data
+                                else None
+                            ),
+                        )
+                    ],
+                    model=request.model,
+                    usage=None,
+                )
+                yield f"data: {finish_reason_chunk.model_dump_json()}\n\n"
 
             # Send hidden states if requested
             if request.return_hidden_states and hidden_states:
@@ -578,7 +583,7 @@ class OpenAIServingChat(OpenAIServingBase):
                                     delta=DeltaMessage(
                                         hidden_states=last_token_hidden_states
                                     ),
-                                    finish_reason=finish_reason_type,
+                                    finish_reason=None,  # Hidden states don't need finish_reason
                                 )
                             ],
                             model=request.model,
@@ -857,7 +862,7 @@ class OpenAIServingChat(OpenAIServingBase):
         parser_dict: Dict[int, FunctionCallParser],
         content: Dict[str, Any],
         request: ChatCompletionRequest,
-        finish_reason_type: Optional[str],
+        has_tool_calls: Dict[int, bool],
     ):
         """Process tool calls in streaming response"""
         if index not in parser_dict:
@@ -874,7 +879,7 @@ class OpenAIServingChat(OpenAIServingBase):
             choice_data = ChatCompletionResponseStreamChoice(
                 index=index,
                 delta=DeltaMessage(content=normal_text),
-                finish_reason=finish_reason_type,
+                finish_reason=None,
             )
             chunk = ChatCompletionStreamResponse(
                 id=content["meta_info"]["id"],
@@ -882,10 +887,13 @@ class OpenAIServingChat(OpenAIServingBase):
                 choices=[choice_data],
                 model=request.model,
             )
-            yield f"data: {chunk.model_dump_json()}\n\n", finish_reason_type
+            yield f"data: {chunk.model_dump_json()}\n\n"
 
         # Yield tool calls
         for call_item in calls:
+            # Mark that this choice has tool calls
+            has_tool_calls[index] = True
+
             # Tool call ID should be generated only once per tool call
             if call_item.name:
                 # First chunk: include ID and function name
@@ -896,23 +904,6 @@ class OpenAIServingChat(OpenAIServingBase):
                 tool_call_id = None
                 function_name = None
 
-            if finish_reason_type == "stop":
-                # Handle remaining arguments
-                latest_delta_len = 0
-                if isinstance(call_item.parameters, str):
-                    latest_delta_len = len(call_item.parameters)
-
-                expected_call = json.dumps(
-                    parser.detector.prev_tool_call_arr[index].get("arguments", {}),
-                    ensure_ascii=False,
-                )
-                actual_call = parser.detector.streamed_args_for_tool[index]
-                if latest_delta_len > 0:
-                    actual_call = actual_call[:-latest_delta_len]
-                remaining_call = expected_call.replace(actual_call, "", 1)
-                call_item.parameters = remaining_call
-                finish_reason_type = "tool_calls"
-
             tool_call = ToolCall(
                 id=tool_call_id,
                 index=call_item.tool_index,
@@ -925,19 +916,84 @@ class OpenAIServingChat(OpenAIServingBase):
             choice_data = ChatCompletionResponseStreamChoice(
                 index=index,
                 delta=DeltaMessage(tool_calls=[tool_call]),
-                finish_reason=(
-                    None
-                    if request.stream_options and request.stream_options.include_usage
-                    else finish_reason_type
+                finish_reason=None,
+            )
+            chunk = ChatCompletionStreamResponse(
+                id=content["meta_info"]["id"],
+                created=int(time.time()),
+                choices=[choice_data],
+                model=request.model,
+            )
+            yield f"data: {chunk.model_dump_json()}\n\n"
+
+    def _check_for_unstreamed_tool_args(
+        self,
+        parser: FunctionCallParser,
+        content: Dict[str, Any],
+        request: ChatCompletionRequest,
+        index: int,
+    ) -> Optional[str]:
+        """
+        Check for any remaining tool call arguments that need to be streamed
+        when generation finishes. This ensures tool calls are properly completed
+        even if the model generates the final arguments in the last chunk.
+        """
+        # Only check if we have tool calls and the parser has tracked data
+        if (
+            not hasattr(parser.detector, "prev_tool_call_arr")
+            or not parser.detector.prev_tool_call_arr
+        ):
+            return None
+
+        if (
+            not hasattr(parser.detector, "streamed_args_for_tool")
+            or not parser.detector.streamed_args_for_tool
+        ):
+            return None
+
+        # Get the last tool call that was being processed
+        tool_index = len(parser.detector.prev_tool_call_arr) - 1
+        if tool_index < 0 or tool_index >= len(parser.detector.streamed_args_for_tool):
+            return None
+
+        # Get expected vs actual arguments
+        expected_args = parser.detector.prev_tool_call_arr[tool_index].get(
+            "arguments", {}
+        )
+        expected_call = json.dumps(expected_args, ensure_ascii=False)
+        actual_call = parser.detector.streamed_args_for_tool[tool_index]
+
+        # Check if there are remaining arguments to send
+        remaining_call = (
+            expected_call.replace(actual_call, "", 1)
+            if actual_call in expected_call
+            else ""
+        )
+
+        if remaining_call:
+            # Create tool call chunk with remaining arguments
+            tool_call = ToolCall(
+                id=None,  # No ID for argument deltas
+                index=tool_index,
+                function=FunctionResponse(
+                    name=None,  # No name for argument deltas
+                    arguments=remaining_call,
                 ),
             )
+
+            choice_data = ChatCompletionResponseStreamChoice(
+                index=index,
+                delta=DeltaMessage(tool_calls=[tool_call]),
+                finish_reason=None,  # Don't send finish_reason with this chunk
+            )
+
             chunk = ChatCompletionStreamResponse(
                 id=content["meta_info"]["id"],
                 created=int(time.time()),
                 choices=[choice_data],
                 model=request.model,
             )
-            yield f"data: {chunk.model_dump_json()}\n\n", finish_reason_type
 
-        if finish_reason_type == "stop":
-            yield None, "tool_calls"
+            return f"data: {chunk.model_dump_json()}\n\n"
+
+        return None

test/srt/openai_server/basic/test_openai_server.py

@@ -233,6 +233,7 @@ class TestOpenAIServer(CustomTestCase):
 
         is_firsts = {}
         is_finished = {}
+        finish_reason_counts = {}
         for response in generator:
             usage = response.usage
             if usage is not None:
@@ -245,6 +246,7 @@ class TestOpenAIServer(CustomTestCase):
             finish_reason = response.choices[0].finish_reason
             if finish_reason is not None:
                 is_finished[index] = True
+                finish_reason_counts[index] = finish_reason_counts.get(index, 0) + 1
 
             data = response.choices[0].delta
 
@@ -284,6 +286,15 @@ class TestOpenAIServer(CustomTestCase):
                 index, True
             ), f"index {index} is not found in the response"
 
+        # Verify that each choice gets exactly one finish_reason chunk
+        for index in range(parallel_sample_num):
+            assert (
+                index in finish_reason_counts
+            ), f"No finish_reason found for index {index}"
+            assert (
+                finish_reason_counts[index] == 1
+            ), f"Expected 1 finish_reason chunk for index {index}, got {finish_reason_counts[index]}"
+
     def test_completion(self):
         for echo in [False, True]:
             for logprobs in [None, 5]:
@@ -420,91 +431,6 @@ The SmartHome Mini is a compact smart home assistant available in black or white
             client.models.retrieve("non-existent-model")
 
 
-# -------------------------------------------------------------------------
-#    EBNF Test Class: TestOpenAIServerEBNF
-#    Launches the server with xgrammar, has only EBNF tests
-# -------------------------------------------------------------------------
-class TestOpenAIServerEBNF(CustomTestCase):
-    @classmethod
-    def setUpClass(cls):
-        cls.model = DEFAULT_SMALL_MODEL_NAME_FOR_TEST
-        cls.base_url = DEFAULT_URL_FOR_TEST
-        cls.api_key = "sk-123456"
-
-        # passing xgrammar specifically
-        other_args = ["--grammar-backend", "xgrammar"]
-        cls.process = popen_launch_server(
-            cls.model,
-            cls.base_url,
-            timeout=DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
-            api_key=cls.api_key,
-            other_args=other_args,
-        )
-        cls.base_url += "/v1"
-        cls.tokenizer = get_tokenizer(DEFAULT_SMALL_MODEL_NAME_FOR_TEST)
-
-    @classmethod
-    def tearDownClass(cls):
-        kill_process_tree(cls.process.pid)
-
-    def test_ebnf(self):
-        """
-        Ensure we can pass `ebnf` to the local openai server
-        and that it enforces the grammar.
-        """
-        client = openai.Client(api_key=self.api_key, base_url=self.base_url)
-        ebnf_grammar = r"""
-        root ::= "Hello" | "Hi" | "Hey"
-        """
-        pattern = re.compile(r"^(Hello|Hi|Hey)[.!?]*\s*$")
-
-        response = client.chat.completions.create(
-            model=self.model,
-            messages=[
-                {"role": "system", "content": "You are a helpful EBNF test bot."},
-                {"role": "user", "content": "Say a greeting (Hello, Hi, or Hey)."},
-            ],
-            temperature=0,
-            max_tokens=32,
-            extra_body={"ebnf": ebnf_grammar},
-        )
-        text = response.choices[0].message.content.strip()
-        self.assertTrue(len(text) > 0, "Got empty text from EBNF generation")
-        self.assertRegex(text, pattern, f"Text '{text}' doesn't match EBNF choices")
-
-    def test_ebnf_strict_json(self):
-        """
-        A stricter EBNF that produces exactly {"name":"Alice"} format
-        with no trailing punctuation or extra fields.
-        """
-        client = openai.Client(api_key=self.api_key, base_url=self.base_url)
-        ebnf_grammar = r"""
-        root    ::= "{" pair "}"
-        pair    ::= "\"name\"" ":" string
-        string  ::= "\"" [A-Za-z]+ "\""
-        """
-        pattern = re.compile(r'^\{"name":"[A-Za-z]+"\}$')
-
-        response = client.chat.completions.create(
-            model=self.model,
-            messages=[
-                {"role": "system", "content": "EBNF mini-JSON generator."},
-                {
-                    "role": "user",
-                    "content": "Generate single key JSON with only letters.",
-                },
-            ],
-            temperature=0,
-            max_tokens=64,
-            extra_body={"ebnf": ebnf_grammar},
-        )
-        text = response.choices[0].message.content.strip()
-        self.assertTrue(len(text) > 0, "Got empty text from EBNF strict JSON test")
-        self.assertRegex(
-            text, pattern, f"Text '{text}' not matching the EBNF strict JSON shape"
-        )
-
-
 class TestOpenAIV1Rerank(CustomTestCase):
     @classmethod
     def setUpClass(cls):

test/srt/openai_server/basic/test_serving_chat.py

@@ -197,6 +197,134 @@ class ServingChatTestCase(unittest.TestCase):
             self.assertEqual(params["min_new_tokens"], 5)
             self.assertEqual(params["stop"], ["</s>"])
 
+    async def test_unstreamed_tool_args_completion(self):
+        """Test that remaining tool call arguments are sent when generation finishes."""
+
+        # Mock FunctionCallParser with detector that has partial tool call data
+        mock_parser = Mock()
+        mock_detector = Mock()
+
+        # Simulate a tool call that was partially streamed
+        mock_detector.prev_tool_call_arr = [
+            {
+                "name": "get_weather",
+                "arguments": {"location": "San Francisco", "unit": "celsius"},
+            }
+        ]
+        mock_detector.streamed_args_for_tool = [
+            '{"location": "San Francisco"'  # Partial arguments streamed so far
+        ]
+        mock_parser.detector = mock_detector
+
+        content = {
+            "meta_info": {
+                "id": "chatcmpl-test123",
+            }
+        }
+
+        request = ChatCompletionRequest(
+            model="test",
+            messages=[{"role": "user", "content": "What's the weather?"}],
+            tools=[{"type": "function", "function": {"name": "get_weather"}}],
+        )
+
+        # Test the completion method
+        result = self.chat._check_for_unstreamed_tool_args(
+            parser=mock_parser,
+            content=content,
+            request=request,
+            finish_reason_type="stop",
+            index=0,
+        )
+
+        # Should return a chunk with remaining arguments
+        self.assertIsNotNone(result, "Should return chunk with remaining arguments")
+        self.assertIn('"arguments":', result, "Should contain arguments field")
+        self.assertIn(
+            ', "unit": "celsius"}', result, "Should contain remaining arguments"
+        )
+        self.assertIn(
+            '"finish_reason":null',
+            result,
+            "Should not include finish_reason in completion chunk",
+        )
+
+    async def test_unstreamed_tool_args_no_completion_needed(self):
+        """Test that no completion chunk is sent when all arguments were already streamed."""
+
+        # Mock FunctionCallParser with detector that has complete tool call data
+        mock_parser = Mock()
+        mock_detector = Mock()
+
+        # Simulate a tool call that was completely streamed
+        mock_detector.prev_tool_call_arr = [
+            {"name": "get_weather", "arguments": {"location": "San Francisco"}}
+        ]
+        mock_detector.streamed_args_for_tool = [
+            '{"location": "San Francisco"}'  # All arguments already streamed
+        ]
+        mock_parser.detector = mock_detector
+
+        content = {
+            "meta_info": {
+                "id": "chatcmpl-test123",
+            }
+        }
+
+        request = ChatCompletionRequest(
+            model="test",
+            messages=[{"role": "user", "content": "What's the weather?"}],
+            tools=[{"type": "function", "function": {"name": "get_weather"}}],
+        )
+
+        # Test the completion method
+        result = self.chat._check_for_unstreamed_tool_args(
+            parser=mock_parser,
+            content=content,
+            request=request,
+            finish_reason_type="stop",
+            index=0,
+        )
+
+        # Should return None since no completion is needed
+        self.assertIsNone(result, "Should return None when no completion is needed")
+
+    async def test_unstreamed_tool_args_no_parser_data(self):
+        """Test that no completion chunk is sent when parser has no tool call data."""
+
+        # Mock FunctionCallParser with empty detector
+        mock_parser = Mock()
+        mock_detector = Mock()
+        mock_detector.prev_tool_call_arr = []
+        mock_detector.streamed_args_for_tool = []
+        mock_parser.detector = mock_detector
+
+        content = {
+            "meta_info": {
+                "id": "chatcmpl-test123",
+            }
+        }
+
+        request = ChatCompletionRequest(
+            model="test",
+            messages=[{"role": "user", "content": "What's the weather?"}],
+            tools=[{"type": "function", "function": {"name": "get_weather"}}],
+        )
+
+        # Test the completion method
+        result = self.chat._check_for_unstreamed_tool_args(
+            parser=mock_parser,
+            content=content,
+            request=request,
+            finish_reason_type="stop",
+            index=0,
+        )
+
+        # Should return None since there's no parser data
+        self.assertIsNone(
+            result, "Should return None when parser has no tool call data"
+        )
+
 
 if __name__ == "__main__":
     unittest.main(verbosity=2)

test/srt/openai_server/function_call/test_openai_function_calling.py

@@ -16,6 +16,20 @@ from sglang.test.test_utils import (
 
 
 class TestOpenAIServerFunctionCalling(CustomTestCase):
+    # NOTE: this system_message is for Llama3.2 system prompt. Without this,
+    # sometimes Llama3.2 gives a different tool call format such as:
+    # '<|python_tag|>{"type": "function", "function": "add", "parameters": {"a": "3", "b": "5"}}'
+    SYSTEM_MESSAGE = (
+        "You are a helpful assistant with tool calling capabilities. "
+        "Only reply with a tool call if the function exists in the library provided by the user. "
+        "If it doesn't exist, just reply directly in natural language. "
+        "When you receive a tool call response, use the output to format an answer to the original user question. "
+        "You have access to the following functions. "
+        "To call a function, please respond with JSON for a function call. "
+        'Respond in the format {"name": function name, "parameters": dictionary of argument name and its value}. '
+        "Do not use variables.\n\n"
+    )
+
     @classmethod
     def setUpClass(cls):
         # Replace with the model name needed for testing; if not required, reuse DEFAULT_SMALL_MODEL_NAME_FOR_TEST
@@ -73,7 +87,10 @@ class TestOpenAIServerFunctionCalling(CustomTestCase):
             }
         ]
 
-        messages = [{"role": "user", "content": "Compute (3+5)"}]
+        messages = [
+            {"role": "system", "content": self.SYSTEM_MESSAGE},
+            {"role": "user", "content": "Compute (3+5)"},
+        ]
         response = client.chat.completions.create(
             model=self.model,
             max_tokens=2048,
@@ -205,7 +222,8 @@ class TestOpenAIServerFunctionCalling(CustomTestCase):
         ]
 
         messages = [
-            {"role": "user", "content": "What is the temperature in Paris in celsius?"}
+            {"role": "system", "content": self.SYSTEM_MESSAGE},
+            {"role": "user", "content": "What is the temperature in Paris?"},
         ]
 
         response_stream = client.chat.completions.create(
@@ -248,74 +266,6 @@ class TestOpenAIServerFunctionCalling(CustomTestCase):
             "Final response of function calling should have finish_reason 'tool_calls'",
         )
 
-    # TODO: There is a bug in sglang preventing this UT from passing. We are working on it. Once done, we will add this UT back.
-    def _test_function_calling_streaming_no_tool_call(self):
-        """
-        Test: Whether the finish_reason is stop in streaming mode when no tool call is given.
-        - Expect no function call to be found.
-        - Verify that finish_reason is stop
-        """
-        client = openai.Client(api_key=self.api_key, base_url=self.base_url)
-
-        tools = [
-            {
-                "type": "function",
-                "function": {
-                    "name": "get_current_weather",
-                    "description": "Get the current weather in a given location",
-                    "parameters": {
-                        "type": "object",
-                        "properties": {
-                            "city": {
-                                "type": "string",
-                                "description": "The city to find the weather for",
-                            },
-                            "unit": {
-                                "type": "string",
-                                "description": "Weather unit (celsius or fahrenheit)",
-                                "enum": ["celsius", "fahrenheit"],
-                            },
-                        },
-                        "required": ["city", "unit"],
-                    },
-                },
-            }
-        ]
-
-        messages = [{"role": "user", "content": "Who are you?"}]
-
-        response_stream = client.chat.completions.create(
-            model=self.model,
-            max_tokens=2048,
-            messages=messages,
-            temperature=0.8,
-            top_p=0.8,
-            stream=True,
-            tools=tools,
-            tool_choice="none",
-        )
-
-        chunks = list(response_stream)
-        self.assertTrue(len(chunks) > 0, "Streaming should return at least one chunk")
-
-        found_tool_call = False
-        for chunk in chunks:
-            choice = chunk.choices[0]
-            # Check whether the current chunk contains tool_calls
-            found_tool_call = choice.delta.tool_calls is not None
-
-        self.assertFalse(
-            found_tool_call,
-            "Shouldn't have any tool_call in the streaming chunks",
-        )
-
-        finish_reason = chunks[-1].choices[0].finish_reason
-        self.assertEqual(
-            finish_reason,
-            "stop",
-            "Final response of no function calling should have finish_reason 'stop'",
-        )
-
     def test_function_calling_streaming_args_parsing(self):
         """
         Test: Whether the function call arguments returned in streaming mode can be correctly concatenated into valid JSON.
@@ -350,7 +300,8 @@ class TestOpenAIServerFunctionCalling(CustomTestCase):
         ]
 
         messages = [
-            {"role": "user", "content": "Please sum 5 and 7, just call the function."}
+            {"role": "system", "content": self.SYSTEM_MESSAGE},
+            {"role": "user", "content": "Please sum 5 and 7, just call the function."},
         ]
 
         response_stream = client.chat.completions.create(
@@ -617,6 +568,212 @@ class TestOpenAIServerFunctionCalling(CustomTestCase):
         )
         self.assertIn("city", args_obj, "Function arguments should have 'city'")
 
+    def test_streaming_multiple_choices_finish_reason(self):
+        """
+        Test: Verify that each choice gets its own finish_reason chunk in streaming mode with n > 1.
+        This tests the fix for the bug where only the last index got a finish_reason chunk.
+        """
+        client = openai.Client(api_key=self.api_key, base_url=self.base_url)
+
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": "get_current_weather",
+                    "description": "Get the current weather in a given location",
+                    "parameters": {
+                        "type": "object",
+                        "properties": {
+                            "location": {
+                                "type": "string",
+                                "description": "The city and state, e.g. San Francisco, CA",
+                            },
+                            "unit": {
+                                "type": "string",
+                                "enum": ["celsius", "fahrenheit"],
+                            },
+                        },
+                        "required": ["location"],
+                    },
+                },
+            }
+        ]
+
+        messages = [
+            {"role": "user", "content": "What is the weather like in Los Angeles?"}
+        ]
+
+        # Request with n=2 to get multiple choices
+        response_stream = client.chat.completions.create(
+            model=self.model,
+            messages=messages,
+            max_tokens=2048,
+            temperature=0.8,
+            stream=True,
+            tools=tools,
+            tool_choice="required",  # Force tool calls
+            n=2,  # Multiple choices
+        )
+
+        chunks = list(response_stream)
+
+        # Track finish_reason chunks for each index
+        finish_reason_chunks = {}
+        for chunk in chunks:
+            if chunk.choices:
+                for choice in chunk.choices:
+                    if choice.finish_reason is not None:
+                        index = choice.index
+                        if index not in finish_reason_chunks:
+                            finish_reason_chunks[index] = []
+                        finish_reason_chunks[index].append(choice.finish_reason)
+
+        # Verify we got finish_reason chunks for both indices
+        self.assertEqual(
+            len(finish_reason_chunks),
+            2,
+            f"Expected finish_reason chunks for 2 indices, got {len(finish_reason_chunks)}",
+        )
+
+        # Verify both index 0 and 1 have finish_reason
+        self.assertIn(
+            0, finish_reason_chunks, "Missing finish_reason chunk for index 0"
+        )
+        self.assertIn(
+            1, finish_reason_chunks, "Missing finish_reason chunk for index 1"
+        )
+
+        # Verify the finish_reason is "tool_calls" since we forced tool calls
+        for index, reasons in finish_reason_chunks.items():
+            self.assertEqual(
+                reasons[-1],  # Last finish_reason for this index
+                "tool_calls",
+                f"Expected finish_reason 'tool_calls' for index {index}, got {reasons[-1]}",
+            )
+
+    def test_function_calling_streaming_no_tool_call(self):
+        """
+        Test: Whether the finish_reason is stop in streaming mode when no tool call is given.
+        - Expect no function call to be found.
+        - Verify that finish_reason is stop
+        """
+        client = openai.Client(api_key=self.api_key, base_url=self.base_url)
+
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": "get_current_weather",
+                    "description": "Get the current weather in a given location",
+                    "parameters": {
+                        "type": "object",
+                        "properties": {
+                            "city": {
+                                "type": "string",
+                                "description": "The city to find the weather for",
+                            },
+                            "unit": {
+                                "type": "string",
+                                "description": "Weather unit (celsius or fahrenheit)",
+                                "enum": ["celsius", "fahrenheit"],
+                            },
+                        },
+                        "required": ["city", "unit"],
+                    },
+                },
+            }
+        ]
+
+        messages = [{"role": "user", "content": "Who are you?"}]
+
+        response_stream = client.chat.completions.create(
+            model=self.model,
+            max_tokens=2048,
+            messages=messages,
+            temperature=0.8,
+            top_p=0.8,
+            stream=True,
+            tools=tools,
+            tool_choice="none",
+        )
+
+        chunks = list(response_stream)
+        self.assertTrue(len(chunks) > 0, "Streaming should return at least one chunk")
+
+        found_tool_call = False
+        for chunk in chunks:
+            choice = chunk.choices[0]
+            # Check whether the current chunk contains tool_calls
+            found_tool_call = choice.delta.tool_calls is not None
+
+        self.assertFalse(
+            found_tool_call,
+            "Shouldn't have any tool_call in the streaming chunks",
+        )
+
+        finish_reason = chunks[-1].choices[0].finish_reason
+        self.assertEqual(
+            finish_reason,
+            "stop",
+            "Final response of no function calling should have finish_reason 'stop'",
+        )
+
+    def test_streaming_multiple_choices_without_tools(self):
+        """
+        Test: Verify that each choice gets its own finish_reason chunk without tool calls.
+        This tests the fix for regular content streaming with multiple choices.
+        """
+        client = openai.Client(api_key=self.api_key, base_url=self.base_url)
+
+        messages = [{"role": "user", "content": "Say hello in one word."}]
+
+        # Request with n=2 to get multiple choices, no tools
+        response_stream = client.chat.completions.create(
+            model=self.model,
+            messages=messages,
+            max_tokens=2048,
+            temperature=0.8,
+            stream=True,
+            max_tokens=10,  # Keep it short
+            n=2,  # Multiple choices
+        )
+
+        chunks = list(response_stream)
+
+        # Track finish_reason chunks for each index
+        finish_reason_chunks = {}
+        for chunk in chunks:
+            if chunk.choices:
+                for choice in chunk.choices:
+                    if choice.finish_reason is not None:
+                        index = choice.index
+                        if index not in finish_reason_chunks:
+                            finish_reason_chunks[index] = []
+                        finish_reason_chunks[index].append(choice.finish_reason)
+
+        # Verify we got finish_reason chunks for both indices
+        self.assertEqual(
+            len(finish_reason_chunks),
+            2,
+            f"Expected finish_reason chunks for 2 indices, got {len(finish_reason_chunks)}",
+        )
+
+        # Verify both index 0 and 1 have finish_reason
+        self.assertIn(
+            0, finish_reason_chunks, "Missing finish_reason chunk for index 0"
+        )
+        self.assertIn(
+            1, finish_reason_chunks, "Missing finish_reason chunk for index 1"
+        )
+
+        # Verify the finish_reason is "stop" (regular completion)
+        for index, reasons in finish_reason_chunks.items():
+            self.assertIn(
+                reasons[-1],
+                ["stop", "length"],  # Could be either depending on how model responds
+                f"Expected finish_reason 'stop' or 'length' for index {index}, got {reasons[-1]}",
+            )
+
 
 class TestOpenAIPythonicFunctionCalling(CustomTestCase):
     PYTHONIC_TOOLS = [
@@ -706,7 +863,6 @@ class TestOpenAIPythonicFunctionCalling(CustomTestCase):
         client = openai.Client(api_key=self.api_key, base_url=self.base_url)
         response = client.chat.completions.create(
             model=self.model,
-            max_tokens=2048,
             messages=self.PYTHONIC_MESSAGES,
             tools=self.PYTHONIC_TOOLS,
             temperature=0.1,
@@ -728,7 +884,6 @@ class TestOpenAIPythonicFunctionCalling(CustomTestCase):
         client = openai.Client(api_key=self.api_key, base_url=self.base_url)
         response_stream = client.chat.completions.create(
             model=self.model,
-            max_tokens=2048,
             messages=self.PYTHONIC_MESSAGES,
             tools=self.PYTHONIC_TOOLS,
             temperature=0.1,