async def _get_runner_async(app_name: str) -> Runner:
    """Returns the runner for the given app."""
    envs.load_dotenv_for_agent(os.path.basename(app_name), agents_dir)
    if app_name in runner_dict:
      return runner_dict[app_name]
    root_agent = agent_loader.load_agent(app_name)
    runner = Runner(
        app_name=agent_engine_id if agent_engine_id else app_name,
        agent=root_agent,
        artifact_service=artifact_service,
        session_service=session_service,
        memory_service=memory_service,
    )
    runner_dict[app_name] = runner
    return runner
Returns the runner for the given app.
src/google/adk/cli/fast_api.py