94 lines
3.1 KiB
Python
94 lines
3.1 KiB
Python
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"""LangGraph 最小脚手架（作业 1）。
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图结构：START → normalize_input → reply → END
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骨架已装配好：状态、节点注册、边和编译（默认 InMemorySaver）。
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两个节点的具体逻辑留待实现（见函数体内的 TODO）。
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离线运行示例：
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python examples/langgraph_smoke.py
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对应测试：test/agent/test_scaffold.py
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"""
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from langgraph.checkpoint.memory import InMemorySaver
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from langgraph.graph import END, START, StateGraph
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from .state import AgentState
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# 脚手架阶段固定返回的阶段码；作业 3 起由转换表驱动。
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DEFAULT_STAGE_CODE = "1002"
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def normalize_input(state: AgentState) -> dict:
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"""归一化本轮输入，为回复节点准备上下文。
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TODO(作业 1): 实现该节点。建议职责：
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- 校验/清理 ``state["input_text"]``（例如去除首尾空白）；
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- 返回需要写入状态的字段增量，例如
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``{"input_text": cleaned}``；
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- 保持纯函数：不读全局状态、不做 IO。
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"""
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cleaned = state["input_text"].strip()
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return {"input_text": cleaned}
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def reply(state: AgentState) -> dict:
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"""生成固定模板回复，并把轮数加一。
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TODO(作业 1): 实现该节点。验收要求：
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- 每次调用使 ``turn_count`` 恰好 +1；首轮会话没有历史
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checkpoint，用 ``state.get("turn_count") or 0`` 起步；
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- ``response_text`` 使用固定模板，**包含本轮输入文本**
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（``state["input_text"]``）；
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- 响应文本需带公共协议前缀，例如
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``<state>1002</state>...``（``stage_code`` 用
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``DEFAULT_STAGE_CODE``，API 层负责解析该前缀）；
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- ``stage_code`` 写入 ``DEFAULT_STAGE_CODE``。
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参考实现::
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turn_count = (state.get("turn_count") or 0) + 1
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response_text = (
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f"<state>{DEFAULT_STAGE_CODE}</state>"
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f"已收到：{state['input_text']}"
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)
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return {
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"turn_count": turn_count,
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"response_text": response_text,
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"stage_code": DEFAULT_STAGE_CODE,
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}
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"""
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turn_count = (state.get("turn_count") or 0) + 1
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response_text = (
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f"<state>{DEFAULT_STAGE_CODE}</state>"
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f"已收到：{state['input_text']}"
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)
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return {
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"turn_count": turn_count,
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"response_text": response_text,
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"stage_code": DEFAULT_STAGE_CODE,
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}
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def build_graph(checkpointer=None):
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"""装配并编译最小图。
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参数:
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checkpointer: 自定义 checkpointer；缺省使用 ``InMemorySaver``。
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作业 7 会替换为 ``AsyncPostgresSaver``。
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返回:
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编译后的图。调用方通过
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``config={"configurable": {"thread_id": <会话 ID>}}``
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区分会话。
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"""
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builder = StateGraph(AgentState)
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builder.add_node("normalize_input", normalize_input)
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builder.add_node("reply", reply)
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builder.add_edge(START, "normalize_input")
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builder.add_edge("normalize_input", "reply")
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builder.add_edge("reply", END)
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return builder.compile(checkpointer=checkpointer or InMemorySaver())
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