fix: do not pass temperature to request if model is oai reasoning model (#2189)

Co-authored-by: Charles Packer <packercharles@gmail.com>

letta/interfaces/openai_streaming_interface.py

@@ -58,9 +58,10 @@ class OpenAIStreamingInterface:
 
     def get_tool_call_object(self) -> ToolCall:
         """Useful for agent loop"""
+        function_name = self.last_flushed_function_name if self.last_flushed_function_name else self.function_name_buffer
         return ToolCall(
             id=self.letta_tool_message_id,
-            function=FunctionCall(arguments=self.current_function_arguments, name=self.last_flushed_function_name),
+            function=FunctionCall(arguments=self.current_function_arguments, name=function_name),
         )
 
     async def process(self, stream: AsyncStream[ChatCompletionChunk]) -> AsyncGenerator[LettaMessage, None]:

letta/llm_api/openai.py

@@ -226,7 +226,7 @@ def build_openai_chat_completions_request(
             tool_choice=tool_choice,
             user=str(user_id),
             max_completion_tokens=llm_config.max_tokens,
-            temperature=llm_config.temperature if supports_temperature_param(model) else None,
+            temperature=llm_config.temperature if supports_temperature_param(model) else 1.0,
             reasoning_effort=llm_config.reasoning_effort,
         )
     else:
@@ -237,7 +237,7 @@ def build_openai_chat_completions_request(
             function_call=function_call,
             user=str(user_id),
             max_completion_tokens=llm_config.max_tokens,
-            temperature=1.0 if llm_config.enable_reasoner else llm_config.temperature,
+            temperature=llm_config.temperature if supports_temperature_param(model) else 1.0,
             reasoning_effort=llm_config.reasoning_effort,
         )
         # https://platform.openai.com/docs/guides/text-generation/json-mode

letta/llm_api/openai_client.py

@@ -41,7 +41,7 @@ def is_openai_reasoning_model(model: str) -> bool:
     """Utility function to check if the model is a 'reasoner'"""
 
     # NOTE: needs to be updated with new model releases
-    is_reasoning = model.startswith("o1") or model.startswith("o3")
+    is_reasoning = model.startswith("o1") or model.startswith("o3") or model.startswith("o4")
     return is_reasoning
 
 
@@ -187,9 +187,9 @@ class OpenAIClient(LLMClientBase):
             tool_choice=tool_choice,
             user=str(),
             max_completion_tokens=llm_config.max_tokens,
-            temperature=llm_config.temperature if supports_temperature_param(model) else None,
+            # NOTE: the reasoners that don't support temperature require 1.0, not None
+            temperature=llm_config.temperature if supports_temperature_param(model) else 1.0,
         )
-
         # always set user id for openai requests
         if self.actor:
             data.user = self.actor.id