如何添加对话历史摘要¶

持久化最常见的用例之一是利用它来跟踪对话历史。这很棒——它让对话的延续变得轻松。然而，随着对话越来越长，这些对话历史会不断累积，占用越来越多的上下文窗口。这通常是不可取的，因为这会导致对大语言模型（LLM）的调用成本更高、耗时更长，还可能引发错误。解决这个问题的一种方法是创建截至目前的对话摘要，并将其与最近的 N 条消息一起使用。本指南将介绍如何实现这一点的示例。

这将涉及几个步骤：

检查对话是否过长（可以通过检查消息数量或消息长度来完成）
如果过长，则创建摘要（这需要一个提示词）
然后删除除最后 N 条消息之外的所有消息

这其中很大一部分工作是删除旧消息。有关如何进行此操作的详细指南，请参阅本指南

安装设置¶

首先，让我们来设置我们要使用的包。

%%capture --no-stderr
%pip install --quiet -U langgraph langchain_anthropic

接下来，我们需要为 Anthropic（我们将使用的大语言模型）设置 API 密钥。

import getpass
import os


def _set_env(var: str):
    if not os.environ.get(var):
        os.environ[var] = getpass.getpass(f"{var}: ")


_set_env("ANTHROPIC_API_KEY")

为 LangGraph 开发设置 LangSmith

注册 LangSmith，以便快速发现问题并提升你的 LangGraph 项目的性能。LangSmith 允许你使用跟踪数据来调试、测试和监控使用 LangGraph 构建的大语言模型应用程序 — 点击此处了解更多关于如何开始使用的信息。

构建聊天机器人¶

现在让我们来构建聊天机器人。

from typing import Literal

from langchain_anthropic import ChatAnthropic
from langchain_core.messages import SystemMessage, RemoveMessage, HumanMessage
from langgraph.checkpoint.memory import MemorySaver
from langgraph.graph import MessagesState, StateGraph, START, END

memory = MemorySaver()


# We will add a `summary` attribute (in addition to `messages` key,
# which MessagesState already has)
class State(MessagesState):
    summary: str


# We will use this model for both the conversation and the summarization
model = ChatAnthropic(model_name="claude-3-haiku-20240307")


# Define the logic to call the model
def call_model(state: State):
    # If a summary exists, we add this in as a system message
    summary = state.get("summary", "")
    if summary:
        system_message = f"Summary of conversation earlier: {summary}"
        messages = [SystemMessage(content=system_message)] + state["messages"]
    else:
        messages = state["messages"]
    response = model.invoke(messages)
    # We return a list, because this will get added to the existing list
    return {"messages": [response]}


# We now define the logic for determining whether to end or summarize the conversation
def should_continue(state: State) -> Literal["summarize_conversation", END]:
    """Return the next node to execute."""
    messages = state["messages"]
    # If there are more than six messages, then we summarize the conversation
    if len(messages) > 6:
        return "summarize_conversation"
    # Otherwise we can just end
    return END


def summarize_conversation(state: State):
    # First, we summarize the conversation
    summary = state.get("summary", "")
    if summary:
        # If a summary already exists, we use a different system prompt
        # to summarize it than if one didn't
        summary_message = (
            f"This is summary of the conversation to date: {summary}\n\n"
            "Extend the summary by taking into account the new messages above:"
        )
    else:
        summary_message = "Create a summary of the conversation above:"

    messages = state["messages"] + [HumanMessage(content=summary_message)]
    response = model.invoke(messages)
    # We now need to delete messages that we no longer want to show up
    # I will delete all but the last two messages, but you can change this
    delete_messages = [RemoveMessage(id=m.id) for m in state["messages"][:-2]]
    return {"summary": response.content, "messages": delete_messages}


# Define a new graph
workflow = StateGraph(State)

# Define the conversation node and the summarize node
workflow.add_node("conversation", call_model)
workflow.add_node(summarize_conversation)

# Set the entrypoint as conversation
workflow.add_edge(START, "conversation")

# We now add a conditional edge
workflow.add_conditional_edges(
    # First, we define the start node. We use `conversation`.
    # This means these are the edges taken after the `conversation` node is called.
    "conversation",
    # Next, we pass in the function that will determine which node is called next.
    should_continue,
)

# We now add a normal edge from `summarize_conversation` to END.
# This means that after `summarize_conversation` is called, we end.
workflow.add_edge("summarize_conversation", END)

# Finally, we compile it!
app = workflow.compile(checkpointer=memory)

API Reference: SystemMessage | RemoveMessage | HumanMessage

使用图表¶

def print_update(update):
    for k, v in update.items():
        for m in v["messages"]:
            m.pretty_print()
        if "summary" in v:
            print(v["summary"])

from langchain_core.messages import HumanMessage

config = {"configurable": {"thread_id": "4"}}
input_message = HumanMessage(content="hi! I'm bob")
input_message.pretty_print()
for event in app.stream({"messages": [input_message]}, config, stream_mode="updates"):
    print_update(event)

input_message = HumanMessage(content="what's my name?")
input_message.pretty_print()
for event in app.stream({"messages": [input_message]}, config, stream_mode="updates"):
    print_update(event)

input_message = HumanMessage(content="i like the celtics!")
input_message.pretty_print()
for event in app.stream({"messages": [input_message]}, config, stream_mode="updates"):
    print_update(event)

API Reference: HumanMessage

================================[1m Human Message [0m=================================

hi! I'm bob
==================================[1m Ai Message [0m==================================

It's nice to meet you, Bob! I'm an AI assistant created by Anthropic. How can I help you today?
================================[1m Human Message [0m=================================

what's my name?
==================================[1m Ai Message [0m==================================

Your name is Bob, as you told me at the beginning of our conversation.
================================[1m Human Message [0m=================================

i like the celtics!
==================================[1m Ai Message [0m==================================

That's great, the Celtics are a fun team to follow! Basketball is an exciting sport. Do you have a favorite Celtics player or a favorite moment from a Celtics game you've watched? I'd be happy to discuss the team and the sport with you.

我们可以看到，到目前为止还没有进行总结——这是因为列表中只有六条消息。

values = app.get_state(config).values
values

{'messages': [HumanMessage(content="hi! I'm bob", id='6534853d-b8a7-44b9-837b-eb7abaf7ebf7'),
  AIMessage(content="It's nice to meet you, Bob! I'm an AI assistant created by Anthropic. How can I help you today?", response_metadata={'id': 'msg_015wCFew2vwMQJcpUh2VZ5ah', 'model': 'claude-3-haiku-20240307', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 12, 'output_tokens': 30}}, id='run-0d33008b-1094-4f5e-94ce-293283fc3024-0'),
  HumanMessage(content="what's my name?", id='0a4f203a-b95a-42a9-b1c5-bb20f68b3251'),
  AIMessage(content='Your name is Bob, as you told me at the beginning of our conversation.', response_metadata={'id': 'msg_01PLp8wg2xDsJbNR9uCtxcGz', 'model': 'claude-3-haiku-20240307', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 50, 'output_tokens': 19}}, id='run-3815dd4d-ee0c-4fc2-9889-f6dd40325961-0'),
  HumanMessage(content='i like the celtics!', id='ac128172-42d1-4390-b7cc-7bcb2d22ee48'),
  AIMessage(content="That's great, the Celtics are a fun team to follow! Basketball is an exciting sport. Do you have a favorite Celtics player or a favorite moment from a Celtics game you've watched? I'd be happy to discuss the team and the sport with you.", response_metadata={'id': 'msg_01CSg5avZEx6CKcZsSvSVXpr', 'model': 'claude-3-haiku-20240307', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 78, 'output_tokens': 61}}, id='run-698faa28-0f72-495f-8ebe-e948664d2200-0')]}

现在让我们再发送一条消息。

input_message = HumanMessage(content="i like how much they win")
input_message.pretty_print()
for event in app.stream({"messages": [input_message]}, config, stream_mode="updates"):
    print_update(event)

================================[1m Human Message [0m=================================

i like how much they win
==================================[1m Ai Message [0m==================================

That's understandable, the Celtics have been one of the more successful NBA franchises over the years. Their history of winning championships is very impressive. It's always fun to follow a team that regularly competes for titles. What do you think has been the key to the Celtics' sustained success? Is there a particular era or team that stands out as your favorite?
================================[1m Remove Message [0m================================


================================[1m Remove Message [0m================================


================================[1m Remove Message [0m================================


================================[1m Remove Message [0m================================


================================[1m Remove Message [0m================================


================================[1m Remove Message [0m================================


Here is a summary of our conversation so far:

- You introduced yourself as Bob and said you like the Boston Celtics basketball team.
- I acknowledged that it's nice to meet you, Bob, and noted that you had shared your name earlier in the conversation.
- You expressed that you like how much the Celtics win, and I agreed that their history of sustained success and championship pedigree is impressive.
- I asked if you have a favorite Celtics player or moment that stands out to you, and invited further discussion about the team and the sport of basketball.
- The overall tone has been friendly and conversational, with me trying to engage with your interest in the Celtics by asking follow-up questions.

如果我们现在查看状态，就可以看到我们有对话的摘要以及最后两条消息。

values = app.get_state(config).values
values

{'messages': [HumanMessage(content='i like how much they win', id='bb916ce7-534c-4d48-9f92-e269f9dc4859'),
  AIMessage(content="That's understandable, the Celtics have been one of the more successful NBA franchises over the years. Their history of winning championships is very impressive. It's always fun to follow a team that regularly competes for titles. What do you think has been the key to the Celtics' sustained success? Is there a particular era or team that stands out as your favorite?", response_metadata={'id': 'msg_01B7TMagaM8xBnYXLSMwUDAG', 'model': 'claude-3-haiku-20240307', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 148, 'output_tokens': 82}}, id='run-c5aa9a8f-7983-4a7f-9c1e-0c0055334ac1-0')],
 'summary': "Here is a summary of our conversation so far:\n\n- You introduced yourself as Bob and said you like the Boston Celtics basketball team.\n- I acknowledged that it's nice to meet you, Bob, and noted that you had shared your name earlier in the conversation.\n- You expressed that you like how much the Celtics win, and I agreed that their history of sustained success and championship pedigree is impressive.\n- I asked if you have a favorite Celtics player or moment that stands out to you, and invited further discussion about the team and the sport of basketball.\n- The overall tone has been friendly and conversational, with me trying to engage with your interest in the Celtics by asking follow-up questions."}

我们现在可以继续对话了！请注意，即使我们只有最后两条消息，我们仍然可以就对话中前面提到的内容向它提问（因为我们已经对那些内容进行了总结）。

input_message = HumanMessage(content="what's my name?")
input_message.pretty_print()
for event in app.stream({"messages": [input_message]}, config, stream_mode="updates"):
    print_update(event)

================================[1m Human Message [0m=================================

what's my name?
==================================[1m Ai Message [0m==================================

In our conversation so far, you introduced yourself as Bob. I acknowledged that earlier when you had shared your name.

input_message = HumanMessage(content="what NFL team do you think I like?")
input_message.pretty_print()
for event in app.stream({"messages": [input_message]}, config, stream_mode="updates"):
    print_update(event)

================================[1m Human Message [0m=================================

what NFL team do you think I like?
==================================[1m Ai Message [0m==================================

I don't actually have any information about what NFL team you might like. In our conversation so far, you've only mentioned that you're a fan of the Boston Celtics basketball team. I don't have any prior knowledge about your preferences for NFL teams. Unless you provide me with that information, I don't have a basis to guess which NFL team you might be a fan of.

input_message = HumanMessage(content="i like the patriots!")
input_message.pretty_print()
for event in app.stream({"messages": [input_message]}, config, stream_mode="updates"):
    print_update(event)

================================[1m Human Message [0m=================================

i like the patriots!
==================================[1m Ai Message [0m==================================

Okay, got it! Thanks for sharing that you're also a fan of the New England Patriots in the NFL. That makes sense, given your interest in other Boston sports teams like the Celtics. The Patriots have also had a very successful run over the past couple of decades, winning multiple Super Bowls. It's fun to follow winning franchises like the Celtics and Patriots. Do you have a favorite Patriots player or moment that stands out to you?
================================[1m Remove Message [0m================================


================================[1m Remove Message [0m================================


================================[1m Remove Message [0m================================


================================[1m Remove Message [0m================================


================================[1m Remove Message [0m================================


================================[1m Remove Message [0m================================


Okay, extending the summary with the new information:

- You initially introduced yourself as Bob and said you like the Boston Celtics basketball team. 
- I acknowledged that and we discussed your appreciation for the Celtics' history of winning.
- You then asked what your name was, and I reminded you that you had introduced yourself as Bob earlier in the conversation.
- You followed up by asking what NFL team I thought you might like, and I explained that I didn't have any prior information about your NFL team preferences.
- You then revealed that you are also a fan of the New England Patriots, which made sense given your Celtics fandom.
- I responded positively to this new information, noting the Patriots' own impressive success and dynasty over the past couple of decades.
- I then asked if you have a particular favorite Patriots player or moment that stands out to you, continuing the friendly, conversational tone.

Overall, the discussion has focused on your sports team preferences, with you sharing that you are a fan of both the Celtics and the Patriots. I've tried to engage with your interests and ask follow-up questions to keep the dialogue flowing.

如何添加对话历史摘要¶

安装设置¶

构建聊天机器人¶

使用图表¶

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