入口和顺序流程对称，只多一行（crew.py:1479）：

# crew.py:1479
def _run_hierarchical_process(self) -> CrewOutput:
    """Creates and assigns a manager agent to complete the tasks."""
    self._create_manager_agent()          # ★唯一的区别：先造经理
    return self._execute_tasks(self.tasks)  # 之后完全复用 Day 20 的引擎

而"必须有经理"这条规则，早在构造 Crew 时就被校验了（crew.py:696）：

# crew.py:696
@model_validator(mode="after")
def check_manager_llm(self) -> Self:
    if self.process == Process.hierarchical:
        if not self.manager_llm and not self.manager_agent:
            raise PydanticCustomError("missing_manager_llm_or_manager_agent",
                "Attribute `manager_llm` or `manager_agent` is required "
                "when using hierarchical process.", {})
        if (self.manager_agent is not None) and (self.agents.count(self.manager_agent) > 0):
            raise PydanticCustomError("manager_agent_in_agents",
                "Manager agent should not be included in agents list.", {})
    return self

核心方法（crew.py:1484），先看"自动造"分支：

# crew.py:1484
def _create_manager_agent(self) -> None:
    if self.manager_agent is not None:
        ...                                      # 用户自定义经理（L04）
    else:
        self.manager_llm = create_llm(self.manager_llm)   # 把字符串/配置变成真 LLM
        i18n = get_i18n(prompt_file=self.prompt_file)
        manager = Agent(
            role=i18n.retrieve("hierarchical_manager_agent", "role"),       # 内置经理人设
            goal=i18n.retrieve("hierarchical_manager_agent", "goal"),
            backstory=i18n.retrieve("hierarchical_manager_agent", "backstory"),
            tools=AgentTools(agents=self.agents).tools(),   # ★把下属打包成委派工具
            allow_delegation=True,
            llm=self.manager_llm,
            verbose=self.verbose,
        )
        self.manager_agent = manager
    manager.crew = self                          # 经理认得自己属于哪个 crew

如果你自己传了 manager_agent（crew.py:1485）：

# crew.py:1485
if self.manager_agent is not None:
    self.manager_agent.allow_delegation = True     # 强制打开委派
    manager = self.manager_agent
    if manager.tools is not None and len(manager.tools) > 0:
        self._logger.log("warning", "Manager agent should not have tools",
                         color="bold_yellow")
        manager.tools = []                          # 清空工具
        raise Exception("Manager agent should not have tools")   # ★并直接报错
else:
    ...   # 自动造（L03）
manager.crew = self

魔法核心（tools/agent_tools/agent_tools.py:16）：

# tools/agent_tools/agent_tools.py:16
class AgentTools:
    """Manager class for agent-related tools"""
    def __init__(self, agents: Sequence[BaseAgent]) -> None:
        self.agents = agents

    def tools(self) -> list[BaseTool]:
        coworkers = ", ".join([f"{agent.role}" for agent in self.agents])   # 下属名单

        delegate_tool = DelegateWorkTool(       # 工具①：把整个任务派给某个下属
            agents=self.agents,
            description=I18N_DEFAULT.tools("delegate_work").format(coworkers=coworkers))
        ask_tool = AskQuestionTool(             # 工具②：只问某个下属一个问题
            agents=self.agents,
            description=I18N_DEFAULT.tools("ask_question").format(coworkers=coworkers))

        return [delegate_tool, ask_tool]

回到 _execute_tasks（Day 20），层级流程下每个 task 用哪个 agent 由这里决定（crew.py:1675）：

# crew.py:1675
def _get_agent_to_use(self, task: Task) -> BaseAgent | None:
    if self.process == Process.hierarchical:
        return self.manager_agent      # ★层级流程：所有 task 都先交给经理
    return task.agent                   # 顺序流程：用 task 自己指定的 agent

# crew.py:1814  执行前给经理补上"委派工具 + task 允许的工具"
def _update_manager_tools(self, task: Task, tools: list[BaseTool]) -> list[BaseTool]:
    if self.manager_agent:
        if task.agent:
            tools = self._update_manager_tools_for_agent(task, tools, self.manager_agent)
        else:
            tools.extend(self.manager_agent.tools or [])   # 把委派工具并进来
    return tools