内存 - Docs by LangChain

AI 应用程序需要内存来跨多个交互共享上下文。在 LangGraph 中，您可以添加两种类型的内存：

添加短期记忆作为智能体状态的一部分，以启用多轮对话。
添加长期记忆以跨会话存储用户特定或应用程序级别的数据。

添加短期记忆

短期记忆（线程级持久化）使智能体能够跟踪多轮对话。要添加短期记忆：

import { MemorySaver, StateGraph } from "@langchain/langgraph";

const checkpointer = new MemorySaver();

const builder = new StateGraph(...);
const graph = builder.compile({ checkpointer });

await graph.invoke(
  { messages: [{ role: "user", content: "hi! i am Bob" }] },
  { configurable: { thread_id: "1" } }
);

在生产环境中使用

在生产环境中，使用由数据库支持的检查点器：

import { PostgresSaver } from "@langchain/langgraph-checkpoint-postgres";

const DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable";
const checkpointer = PostgresSaver.fromConnString(DB_URI);

const builder = new StateGraph(...);
const graph = builder.compile({ checkpointer });

示例：使用 Postgres 检查点器

npm install @langchain/langgraph-checkpoint-postgres

首次使用 Postgres 检查点器时，您需要调用 checkpointer.setup()

import { ChatAnthropic } from "@langchain/anthropic";
import { StateGraph, MessagesZodMeta, START } from "@langchain/langgraph";
import { BaseMessage } from "@langchain/core/messages";
import { registry } from "@langchain/langgraph/zod";
import * as z from "zod";
import { PostgresSaver } from "@langchain/langgraph-checkpoint-postgres";

const MessagesZodState = z.object({
  messages: z
    .array(z.custom<BaseMessage>())
    .register(registry, MessagesZodMeta),
});

const model = new ChatAnthropic({ model: "claude-haiku-4-5-20251001" });

const DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable";
const checkpointer = PostgresSaver.fromConnString(DB_URI);
// await checkpointer.setup();

const builder = new StateGraph(MessagesZodState)
  .addNode("call_model", async (state) => {
    const response = await model.invoke(state.messages);
    return { messages: [response] };
  })
  .addEdge(START, "call_model");

const graph = builder.compile({ checkpointer });

const config = {
  configurable: {
    thread_id: "1"
  }
};

for await (const chunk of await graph.stream(
  { messages: [{ role: "user", content: "hi! I'm bob" }] },
  { ...config, streamMode: "values" }
)) {
  console.log(chunk.messages.at(-1)?.content);
}

for await (const chunk of await graph.stream(
  { messages: [{ role: "user", content: "what's my name?" }] },
  { ...config, streamMode: "values" }
)) {
  console.log(chunk.messages.at(-1)?.content);
}

在子图中使用

如果您的图包含子图，您只需要在编译父图时提供检查点器。LangGraph 会自动将检查点器传播到子图。

import { StateGraph, START, MemorySaver } from "@langchain/langgraph";
import * as z from "zod";

const State = z.object({ foo: z.string() });

const subgraphBuilder = new StateGraph(State)
  .addNode("subgraph_node_1", (state) => {
    return { foo: state.foo + "bar" };
  })
  .addEdge(START, "subgraph_node_1");
const subgraph = subgraphBuilder.compile();

const builder = new StateGraph(State)
  .addNode("node_1", subgraph)
  .addEdge(START, "node_1");

const checkpointer = new MemorySaver();
const graph = builder.compile({ checkpointer });

If you want the subgraph to have its own memory, you can compile it with the appropriate checkpointer option. This is useful in multi-agent systems, if you want agents to keep track of their internal message histories.

const subgraphBuilder = new StateGraph(...);
const subgraph = subgraphBuilder.compile({ checkpointer: true });  

添加长期记忆

使用长期记忆来存储跨对话的用户特定或应用程序特定数据。

import { InMemoryStore, StateGraph } from "@langchain/langgraph";

const store = new InMemoryStore();

const builder = new StateGraph(...);
const graph = builder.compile({ store });

在生产中使用

在生产中，使用由数据库支持的存储：

import { PostgresStore } from "@langchain/langgraph-checkpoint-postgres/store";

const DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable";
const store = PostgresStore.fromConnString(DB_URI);

const builder = new StateGraph(...);
const graph = builder.compile({ store });

Example: using Postgres store

npm install @langchain/langgraph-checkpoint-postgres

You need to call store.setup() the first time you’re using Postgres store

import { ChatAnthropic } from "@langchain/anthropic";
import { StateGraph, MessagesZodMeta, START, LangGraphRunnableConfig } from "@langchain/langgraph";
import { PostgresSaver } from "@langchain/langgraph-checkpoint-postgres";
import { PostgresStore } from "@langchain/langgraph-checkpoint-postgres/store";
import { BaseMessage } from "@langchain/core/messages";
import { registry } from "@langchain/langgraph/zod";
import * as z from "zod";
import { v4 as uuidv4 } from "uuid";

const MessagesZodState = z.object({
  messages: z
    .array(z.custom<BaseMessage>())
    .register(registry, MessagesZodMeta),
});

const model = new ChatAnthropic({ model: "claude-haiku-4-5-20251001" });

const DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable";

const store = PostgresStore.fromConnString(DB_URI);
const checkpointer = PostgresSaver.fromConnString(DB_URI);
// await store.setup();
// await checkpointer.setup();

const callModel = async (
  state: z.infer<typeof MessagesZodState>,
  config: LangGraphRunnableConfig,
) => {
  const userId = config.configurable?.userId;
  const namespace = ["memories", userId];
  const memories = await config.store?.search(namespace, { query: state.messages.at(-1)?.content });
  const info = memories?.map(d => d.value.data).join("\n") || "";
  const systemMsg = `You are a helpful assistant talking to the user. User info: ${info}`;

  // Store new memories if the user asks the model to remember
  const lastMessage = state.messages.at(-1);
  if (lastMessage?.content?.toLowerCase().includes("remember")) {
    const memory = "User name is Bob";
    await config.store?.put(namespace, uuidv4(), { data: memory });
  }

  const response = await model.invoke([
    { role: "system", content: systemMsg },
    ...state.messages
  ]);
  return { messages: [response] };
};

const builder = new StateGraph(MessagesZodState)
  .addNode("call_model", callModel)
  .addEdge(START, "call_model");

const graph = builder.compile({
  checkpointer,
  store,
});

const config = {
  configurable: {
    thread_id: "1",
    userId: "1",
  }
};

for await (const chunk of await graph.stream(
  { messages: [{ role: "user", content: "Hi! Remember: my name is Bob" }] },
  { ...config, streamMode: "values" }
)) {
  console.log(chunk.messages.at(-1)?.content);
}

const config2 = {
  configurable: {
    thread_id: "2",
    userId: "1",
  }
};

for await (const chunk of await graph.stream(
  { messages: [{ role: "user", content: "what is my name?" }] },
  { ...config2, streamMode: "values" }
)) {
  console.log(chunk.messages.at(-1)?.content);
}

使用语义搜索

在图的内存存储中启用语义搜索，让图智能体通过语义相似性搜索存储中的项目。

import { OpenAIEmbeddings } from "@langchain/openai";
import { InMemoryStore } from "@langchain/langgraph";

// Create store with semantic search enabled
const embeddings = new OpenAIEmbeddings({ model: "text-embedding-3-small" });
const store = new InMemoryStore({
  index: {
    embeddings,
    dims: 1536,
  },
});

await store.put(["user_123", "memories"], "1", { text: "I love pizza" });
await store.put(["user_123", "memories"], "2", { text: "I am a plumber" });

const items = await store.search(["user_123", "memories"], {
  query: "I'm hungry",
  limit: 1,
});

Long-term memory with semantic search

import { OpenAIEmbeddings, ChatOpenAI } from "@langchain/openai";
import { StateGraph, START, MessagesZodMeta, InMemoryStore } from "@langchain/langgraph";
import { BaseMessage } from "@langchain/core/messages";
import { registry } from "@langchain/langgraph/zod";
import * as z from "zod";

const MessagesZodState = z.object({
    messages: z
    .array(z.custom<BaseMessage>())
    .register(registry, MessagesZodMeta),
});

const model = new ChatOpenAI({ model: "gpt-4o-mini" });

// Create store with semantic search enabled
const embeddings = new OpenAIEmbeddings({ model: "text-embedding-3-small" });
const store = new InMemoryStore({
    index: {
    embeddings,
    dims: 1536,
    }
});

await store.put(["user_123", "memories"], "1", { text: "I love pizza" });
await store.put(["user_123", "memories"], "2", { text: "I am a plumber" });

const chat = async (state: z.infer<typeof MessagesZodState>, config) => {
    // Search based on user's last message
    const items = await config.store.search(
    ["user_123", "memories"],
    { query: state.messages.at(-1)?.content, limit: 2 }
    );
    const memories = items.map(item => item.value.text).join("\n");
    const memoriesText = memories ? `## Memories of user\n${memories}` : "";

    const response = await model.invoke([
    { role: "system", content: `You are a helpful assistant.\n${memoriesText}` },
    ...state.messages,
    ]);

    return { messages: [response] };
};

const builder = new StateGraph(MessagesZodState)
    .addNode("chat", chat)
    .addEdge(START, "chat");
const graph = builder.compile({ store });

for await (const [message, metadata] of await graph.stream(
    { messages: [{ role: "user", content: "I'm hungry" }] },
    { streamMode: "messages" }
)) {
    if (message.content) {
    console.log(message.content);
    }
}

管理短期记忆

启用短期记忆后，长对话可能会超过 LLM 的上下文窗口。常见的解决方案是：

修剪消息：删除前 N 条或后 N 条消息（在调用 LLM 之前）
删除消息：从 LangGraph 状态中永久删除
摘要消息：摘要历史中的早期消息并用摘要替换它们
管理检查点以存储和检索消息历史
自定义策略（例如，消息过滤等）

这允许智能体跟踪对话而不会超过 LLM 的上下文窗口。

修剪消息

Most LLMs have a maximum supported context window (denominated in tokens). One way to decide when to truncate messages is to count the tokens in the message history and truncate whenever it approaches that limit. If you’re using LangChain, you can use the trim messages utility and specify the number of tokens to keep from the list, as well as the strategy (e.g., keep the last maxTokens) to use for handling the boundary. To trim message history, use the trimMessages function:

import { trimMessages } from "@langchain/core/messages";

const callModel = async (state: z.infer<typeof MessagesZodState>) => {
  const messages = trimMessages(state.messages, {
    strategy: "last",
    maxTokens: 128,
    startOn: "human",
    endOn: ["human", "tool"],
  });
  const response = await model.invoke(messages);
  return { messages: [response] };
};

const builder = new StateGraph(MessagesZodState)
  .addNode("call_model", callModel);
// ...

Full example: trim messages

import { trimMessages, BaseMessage } from "@langchain/core/messages";
import { ChatAnthropic } from "@langchain/anthropic";
import { StateGraph, START, MessagesZodMeta, MemorySaver } from "@langchain/langgraph";
import { registry } from "@langchain/langgraph/zod";
import * as z from "zod";

const MessagesZodState = z.object({
  messages: z
    .array(z.custom<BaseMessage>())
    .register(registry, MessagesZodMeta),
});

const model = new ChatAnthropic({ model: "claude-3-5-sonnet-20241022" });

const callModel = async (state: z.infer<typeof MessagesZodState>) => {
  const messages = trimMessages(state.messages, {
    strategy: "last",
    maxTokens: 128,
    startOn: "human",
    endOn: ["human", "tool"],
    tokenCounter: model,
  });
  const response = await model.invoke(messages);
  return { messages: [response] };
};

const checkpointer = new MemorySaver();
const builder = new StateGraph(MessagesZodState)
  .addNode("call_model", callModel)
  .addEdge(START, "call_model");
const graph = builder.compile({ checkpointer });

const config = { configurable: { thread_id: "1" } };
await graph.invoke({ messages: [{ role: "user", content: "hi, my name is bob" }] }, config);
await graph.invoke({ messages: [{ role: "user", content: "write a short poem about cats" }] }, config);
await graph.invoke({ messages: [{ role: "user", content: "now do the same but for dogs" }] }, config);
const finalResponse = await graph.invoke({ messages: [{ role: "user", content: "what's my name?" }] }, config);

console.log(finalResponse.messages.at(-1)?.content);

Your name is Bob, as you mentioned when you first introduced yourself.

删除消息

您可以从图状态中删除消息以管理消息历史。当您想要删除特定消息或清除整个消息历史时，这很有用。 To delete messages from the graph state, you can use the RemoveMessage. For RemoveMessage to work, you need to use a state key with messagesStateReducer reducer, like MessagesZodState. To remove specific messages:

import { RemoveMessage } from "@langchain/core/messages";

const deleteMessages = (state) => {
  const messages = state.messages;
  if (messages.length > 2) {
    // remove the earliest two messages
    return {
      messages: messages
        .slice(0, 2)
        .map((m) => new RemoveMessage({ id: m.id })),
    };
  }
};

When deleting messages, make sure that the resulting message history is valid. Check the limitations of the LLM provider you’re using. For example:

some providers expect message history to start with a user message
most providers require assistant messages with tool calls to be followed by corresponding tool result messages.

Full example: delete messages

import { RemoveMessage, BaseMessage } from "@langchain/core/messages";
import { ChatAnthropic } from "@langchain/anthropic";
import { StateGraph, START, MemorySaver, MessagesZodMeta } from "@langchain/langgraph";
import * as z from "zod";
import { registry } from "@langchain/langgraph/zod";

const MessagesZodState = z.object({
  messages: z
    .array(z.custom<BaseMessage>())
    .register(registry, MessagesZodMeta),
});

const model = new ChatAnthropic({ model: "claude-3-5-sonnet-20241022" });

const deleteMessages = (state: z.infer<typeof MessagesZodState>) => {
  const messages = state.messages;
  if (messages.length > 2) {
    // remove the earliest two messages
    return { messages: messages.slice(0, 2).map(m => new RemoveMessage({ id: m.id })) };
  }
  return {};
};

const callModel = async (state: z.infer<typeof MessagesZodState>) => {
  const response = await model.invoke(state.messages);
  return { messages: [response] };
};

const builder = new StateGraph(MessagesZodState)
  .addNode("call_model", callModel)
  .addNode("delete_messages", deleteMessages)
  .addEdge(START, "call_model")
  .addEdge("call_model", "delete_messages");

const checkpointer = new MemorySaver();
const app = builder.compile({ checkpointer });

const config = { configurable: { thread_id: "1" } };

for await (const event of await app.stream(
  { messages: [{ role: "user", content: "hi! I'm bob" }] },
  { ...config, streamMode: "values" }
)) {
  console.log(event.messages.map(message => [message.getType(), message.content]));
}

for await (const event of await app.stream(
  { messages: [{ role: "user", content: "what's my name?" }] },
  { ...config, streamMode: "values" }
)) {
  console.log(event.messages.map(message => [message.getType(), message.content]));
}

[['human', "hi! I'm bob"]]
[['human', "hi! I'm bob"], ['ai', 'Hi Bob! How are you doing today? Is there anything I can help you with?']]
[['human', "hi! I'm bob"], ['ai', 'Hi Bob! How are you doing today? Is there anything I can help you with?'], ['human', "what's my name?"]]
[['human', "hi! I'm bob"], ['ai', 'Hi Bob! How are you doing today? Is there anything I can help you with?'], ['human', "what's my name?"], ['ai', 'Your name is Bob.']]
[['human', "what's my name?"], ['ai', 'Your name is Bob.']]

摘要消息

如上所示，修剪或删除消息的问题在于您可能会因消息队列的清理而丢失信息。因此，某些应用程序受益于使用聊天模型对消息历史进行摘要的更复杂方法。

Prompting and orchestration logic can be used to summarize the message history. For example, in LangGraph you can include a summary key in the state alongside the messages key:

import { BaseMessage } from "@langchain/core/messages";
import { MessagesZodMeta } from "@langchain/langgraph";
import { registry } from "@langchain/langgraph/zod";
import * as z from "zod";

const State = z.object({
  messages: z
    .array(z.custom<BaseMessage>())
    .register(registry, MessagesZodMeta),
  summary: z.string().optional(),
});

Then, you can generate a summary of the chat history, using any existing summary as context for the next summary. This summarizeConversation node can be called after some number of messages have accumulated in the messages state key.

import { RemoveMessage, HumanMessage } from "@langchain/core/messages";

const summarizeConversation = async (state: z.infer<typeof State>) => {
  // First, we get any existing summary
  const summary = state.summary || "";

  // Create our summarization prompt
  let summaryMessage: string;
  if (summary) {
    // A summary already exists
    summaryMessage =
      `This is a summary of the conversation to date: ${summary}\n\n` +
      "Extend the summary by taking into account the new messages above:";
  } else {
    summaryMessage = "Create a summary of the conversation above:";
  }

  // Add prompt to our history
  const messages = [
    ...state.messages,
    new HumanMessage({ content: summaryMessage })
  ];
  const response = await model.invoke(messages);

  // Delete all but the 2 most recent messages
  const deleteMessages = state.messages
    .slice(0, -2)
    .map(m => new RemoveMessage({ id: m.id }));

  return {
    summary: response.content,
    messages: deleteMessages
  };
};

Full example: summarize messages

import { ChatAnthropic } from "@langchain/anthropic";
import {
  SystemMessage,
  HumanMessage,
  RemoveMessage,
  type BaseMessage
} from "@langchain/core/messages";
import {
  MessagesZodMeta,
  StateGraph,
  START,
  END,
  MemorySaver,
} from "@langchain/langgraph";
import { BaseMessage } from "@langchain/core/messages";
import { registry } from "@langchain/langgraph/zod";
import * as z from "zod";
import { v4 as uuidv4 } from "uuid";

const memory = new MemorySaver();

// We will add a `summary` attribute (in addition to `messages` key,
// which MessagesZodState already has)
const GraphState = z.object({
  messages: z
    .array(z.custom<BaseMessage>())
    .register(registry, MessagesZodMeta),
  summary: z.string().default(""),
});

// We will use this model for both the conversation and the summarization
const model = new ChatAnthropic({ model: "claude-haiku-4-5-20251001" });

// Define the logic to call the model
const callModel = async (state: z.infer<typeof GraphState>) => {
  // If a summary exists, we add this in as a system message
  const { summary } = state;
  let { messages } = state;
  if (summary) {
    const systemMessage = new SystemMessage({
      id: uuidv4(),
      content: `Summary of conversation earlier: ${summary}`,
    });
    messages = [systemMessage, ...messages];
  }
  const response = await model.invoke(messages);
  // We return an object, because this will get added to the existing state
  return { messages: [response] };
};

// We now define the logic for determining whether to end or summarize the conversation
const shouldContinue = (state: z.infer<typeof GraphState>) => {
  const messages = state.messages;
  // If there are more than six messages, then we summarize the conversation
  if (messages.length > 6) {
    return "summarize_conversation";
  }
  // Otherwise we can just end
  return END;
};

const summarizeConversation = async (state: z.infer<typeof GraphState>) => {
  // First, we summarize the conversation
  const { summary, messages } = state;
  let summaryMessage: string;
  if (summary) {
    // If a summary already exists, we use a different system prompt
    // to summarize it than if one didn't
    summaryMessage =
      `This is summary of the conversation to date: ${summary}\n\n` +
      "Extend the summary by taking into account the new messages above:";
  } else {
    summaryMessage = "Create a summary of the conversation above:";
  }

  const allMessages = [
    ...messages,
    new HumanMessage({ id: uuidv4(), content: summaryMessage }),
  ];

  const response = await model.invoke(allMessages);

  // 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
  const deleteMessages = messages
    .slice(0, -2)
    .map((m) => new RemoveMessage({ id: m.id! }));

  if (typeof response.content !== "string") {
    throw new Error("Expected a string response from the model");
  }

  return { summary: response.content, messages: deleteMessages };
};

// Define a new graph
const workflow = new StateGraph(GraphState)
  // Define the conversation node and the summarize node
  .addNode("conversation", callModel)
  .addNode("summarize_conversation", summarizeConversation)
  // Set the entrypoint as conversation
  .addEdge(START, "conversation")
  // We now add a conditional edge
  .addConditionalEdges(
    // 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.
    shouldContinue,
  )
  // We now add a normal edge from `summarize_conversation` to END.
  // This means that after `summarize_conversation` is called, we end.
  .addEdge("summarize_conversation", END);

// Finally, we compile it!
const app = workflow.compile({ checkpointer: memory });

Manage checkpoints

You can view and delete the information stored by the checkpointer.

View thread state

const config = {
  configurable: {
    thread_id: "1",
    // optionally provide an ID for a specific checkpoint,
    // otherwise the latest checkpoint is shown
    // checkpoint_id: "1f029ca3-1f5b-6704-8004-820c16b69a5a"
  },
};
await graph.getState(config);

{
  values: { messages: [HumanMessage(...), AIMessage(...), HumanMessage(...), AIMessage(...)] },
  next: [],
  config: { configurable: { thread_id: '1', checkpoint_ns: '', checkpoint_id: '1f029ca3-1f5b-6704-8004-820c16b69a5a' } },
  metadata: {
    source: 'loop',
    writes: { call_model: { messages: AIMessage(...) } },
    step: 4,
    parents: {},
    thread_id: '1'
  },
  createdAt: '2025-05-05T16:01:24.680462+00:00',
  parentConfig: { configurable: { thread_id: '1', checkpoint_ns: '', checkpoint_id: '1f029ca3-1790-6b0a-8003-baf965b6a38f' } },
  tasks: [],
  interrupts: []
}

View the history of the thread

const config = {
  configurable: {
    thread_id: "1",
  },
};

const history = [];
for await (const state of graph.getStateHistory(config)) {
  history.push(state);
}

Delete all checkpoints for a thread

const threadId = "1";
await checkpointer.deleteThread(threadId);

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LangGraph v1.0

Get started

Capabilities

Production

LangGraph APIs

内存

添加短期记忆

在生产环境中使用

在子图中使用

添加长期记忆

在生产中使用

使用语义搜索

管理短期记忆

修剪消息

删除消息

摘要消息

Manage checkpoints

View thread state

View the history of the thread

Delete all checkpoints for a thread

LangGraph v1.0

Get started

Capabilities

Production

LangGraph APIs

​添加短期记忆

​在生产环境中使用

​在子图中使用

​添加长期记忆

​在生产中使用

​使用语义搜索

​管理短期记忆

​修剪消息

​删除消息

​摘要消息

​Manage checkpoints

​View thread state

​View the history of the thread

​Delete all checkpoints for a thread

添加短期记忆

在生产环境中使用

在子图中使用

添加长期记忆

在生产中使用

使用语义搜索

管理短期记忆

修剪消息

删除消息

摘要消息

Manage checkpoints

View thread state

View the history of the thread

Delete all checkpoints for a thread