Please read this first

• Have you read the docs?Agents SDK docs - Yes
• Have you searched for related issues? Others may have faced similar issues. - Yes

Describe the bug

A clear and concise description of what the bug is.

Debug information

• Agents SDK version: (e.g. v0.0.3)
• Python version (e.g. Python 3.10)

Repro steps

 custom_stt_settings = STTModelSettings(
    language="English" 
)

custom_tts_settings = TTSModelSettings(
    voice="alloy"
)

pipeline_config = VoicePipelineConfig(
    stt_settings=custom_stt_settings,
    tts_settings=custom_tts_settings
)


async def main() -> None:
    #Sets up the voice pipeline, microphone audio reading, and keyboard listener concurrently.

    should_send_audio = asyncio.Event()

    pipeline = VoicePipeline(
        workflow=MyWorkflow(on_start=lambda transcription: print(f"Transcription: {transcription}")),
        config=pipeline_config,
        stt_model="gpt-4o-mini-transcribe",

    )
    audio_input = StreamedAudioInput()


    task_pipeline = asyncio.create_task(run_voice_pipeline(pipeline, audio_input))
    task_mic = asyncio.create_task(send_mic_audio(audio_input, should_send_audio))
    task_keyboard = asyncio.create_task(keyboard_listener(should_send_audio))

    await task_keyboard

    task_pipeline.cancel()
    task_mic.cancel()
    await asyncio.gather(task_pipeline, task_mic, return_exceptions=True)

"""This is the Agent"""
agent = Agent(
    name="Assistant",
    instructions=prompt_with_handoff_instructions(
        "You are a Fleet Assistant, an intelligent assistant that transforms raw data into clear and natural language summaries. Your task is to analyze the provided information and convey the key details in a simple, concise, and professional manner.Take inputs for the particluar tool one after the other .Today's date is :24-03-2025.Take input in english and respond in english. Wait for the user to complete their sentences, don't start generating a response after a pause.",
    ),
    model="gpt-4o-mini",
    # handoffs=[spanish_agent],
    tools=[fetch_alerts,fetch_trip_data,getmaintainencereport,Vehicle_Location_Status_lasttrip,getfleethighlights,getvehicleidlestatus],
)

"""This is the WorkFlow class"""
class MyWorkflow(VoiceWorkflowBase):
    def __init__(self, on_start: Callable[[str], None]):
        """
        Args:
            on_start: A callback that is called when the workflow starts. The transcription
                is passed in as an argument.
        """
        self._input_history: list[TResponseInputItem] = []
        self._current_agent = agent
        self._on_start = on_start

    async def run(self, transcription: str) -> AsyncIterator[str]:
        self._on_start(transcription)

        self._input_history.append(
            {
                "role": "user",
                "content": transcription,
            }
        )

        result = Runner.run_streamed(self._current_agent, self._input_history)

        async for chunk in VoiceWorkflowHelper.stream_text_from(result):
            yield chunk

        self._input_history = result.to_input_list()
        self._current_agent = result.last_agent 

Ideally provide a minimal python script that can be run to reproduce the bug.

Expected behavior

A clear and concise description of what you expected to happen.