npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

@langchain/langgraph-checkpoint

v0.0.11

Published

Library with base interfaces for LangGraph checkpoint savers.

Downloads

121,549

Readme

@langchain/langgraph-checkpoint

This library defines the base interface for LangGraph.js checkpointers. Checkpointers provide persistence layer for LangGraph. They allow you to interact with and manage the graph's state. When you use a graph with a checkpointer, the checkpointer saves a checkpoint of the graph state at every superstep, enabling several powerful capabilities like human-in-the-loop, "memory" between interactions and more.

Key concepts

Checkpoint

Checkpoint is a snapshot of the graph state at a given point in time. Checkpoint tuple refers to an object containing checkpoint and the associated config, metadata and pending writes.

Thread

Threads enable the checkpointing of multiple different runs, making them essential for multi-tenant chat applications and other scenarios where maintaining separate states is necessary. A thread is a unique ID assigned to a series of checkpoints saved by a checkpointer. When using a checkpointer, you must specify a thread_id and optionally checkpoint_id when running the graph.

  • thread_id is simply the ID of a thread. This is always required
  • checkpoint_id can optionally be passed. This identifier refers to a specific checkpoint within a thread. This can be used to kick of a run of a graph from some point halfway through a thread.

You must pass these when invoking the graph as part of the configurable part of the config, e.g.

{ configurable: { thread_id: "1" } }  // valid config
{ configurable: { thread_id: "1", checkpoint_id: "0c62ca34-ac19-445d-bbb0-5b4984975b2a" } }  // also valid config

Serde

@langchain/langgraph-checkpoint also defines protocol for serialization/deserialization (serde) and provides an default implementation that handles a range of types.

Pending writes

When a graph node fails mid-execution at a given superstep, LangGraph stores pending checkpoint writes from any other nodes that completed successfully at that superstep, so that whenever we resume graph execution from that superstep we don't re-run the successful nodes.

Interface

Each checkpointer should conform to BaseCheckpointSaver interface and must implement the following methods:

  • .put - Store a checkpoint with its configuration and metadata.
  • .putWrites - Store intermediate writes linked to a checkpoint (i.e. pending writes).
  • .getTuple - Fetch a checkpoint tuple using for a given configuration (thread_id and thread_ts).
  • .list - List checkpoints that match a given configuration and filter criteria.

Usage

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

const writeConfig = {
  configurable: {
    thread_id: "1",
    checkpoint_ns: ""
  }
};
const readConfig = {
  configurable: {
    thread_id: "1"
  }
};

const checkpointer = new MemorySaver();
const checkpoint = {
  v: 1,
  ts: "2024-07-31T20:14:19.804150+00:00",
  id: "1ef4f797-8335-6428-8001-8a1503f9b875",
  channel_values: {
    my_key: "meow",
    node: "node"
  },
  channel_versions: {
    __start__: 2,
    my_key: 3,
    start:node: 3,
    node: 3
  },
  versions_seen: {
    __input__: {},
    __start__: {
      __start__: 1
    },
    node: {
      start:node: 2
    }
  },
  pending_sends: [],
}

// store checkpoint
await checkpointer.put(writeConfig, checkpoint, {}, {})

// load checkpoint
await checkpointer.get(readConfig)

// list checkpoints
for await (const checkpoint of checkpointer.list(readConfig)) {
  console.log(checkpoint);
}