def load_agent(self, agent_name: str) -> BaseAgent:
    """Load an agent module (with caching & .env) and return its root_agent."""
    if agent_name in self._agent_cache:
      logger.debug("Returning cached agent for %s (async)", agent_name)
      return self._agent_cache[agent_name]

    logger.debug("Loading agent %s - not in cache.", agent_name)
    agent = self._perform_load(agent_name)
    self._agent_cache[agent_name] = agent
    return agent
Load an agent module (with caching & .env) and return its root_agent.
src/google/adk/cli/utils/agent_loader.py