# LangGraph

> LangGraph is a framework for building stateful, multi-actor applications with LLMs. Gain control with LangGraph to design agents that reliably handle complex tasks.

LangGraph documentation has moved to https://docs.langchain.com/oss/python/langgraph/overview.

## Docs

- [LangGraph overview](https://docs.langchain.com/oss/python/langgraph/overview): Gain control with LangGraph to design agents that reliably handle complex tasks
- [Quickstart](https://docs.langchain.com/oss/python/langgraph/quickstart): Build your first LangGraph agent
- [Install LangGraph](https://docs.langchain.com/oss/python/langgraph/install): Install the LangGraph package
- [Thinking in LangGraph](https://docs.langchain.com/oss/python/langgraph/thinking-in-langgraph): Learn how to think about building agents with LangGraph
- [Workflows and agents](https://docs.langchain.com/oss/python/langgraph/workflows-agents): Understand the difference between workflows and agents in LangGraph

## APIs

- [Graph API overview](https://docs.langchain.com/oss/python/langgraph/graph-api): Learn about the Graph API for building stateful applications
- [Use the graph API](https://docs.langchain.com/oss/python/langgraph/use-graph-api): Build agents using the Graph API
- [Functional API overview](https://docs.langchain.com/oss/python/langgraph/functional-api): Learn about the Functional API for building agents
- [Use the functional API](https://docs.langchain.com/oss/python/langgraph/use-functional-api): Build agents using the Functional API
- [Choosing between Graph and Functional APIs](https://docs.langchain.com/oss/python/langgraph/choosing-apis): Decide which API to use for your use case

## Core Concepts

- [Persistence](https://docs.langchain.com/oss/python/langgraph/persistence): Save and restore graph state
- [Memory](https://docs.langchain.com/oss/python/langgraph/add-memory): Add memory to your agents
- [Memory overview](https://docs.langchain.com/oss/python/langgraph/memory): Understand memory concepts in LangGraph
- [Streaming](https://docs.langchain.com/oss/python/langgraph/streaming): Stream outputs from your graphs
- [Interrupts](https://docs.langchain.com/oss/python/langgraph/interrupts): Pause and resume graph execution for human-in-the-loop workflows
- [Subgraphs](https://docs.langchain.com/oss/python/langgraph/use-subgraphs): Compose graphs with subgraphs
- [Durable execution](https://docs.langchain.com/oss/python/langgraph/durable-execution): Build resilient agents with durable execution
- [Use time-travel](https://docs.langchain.com/oss/python/langgraph/use-time-travel): Debug and replay agent execution

## Architecture

- [Application structure](https://docs.langchain.com/oss/python/langgraph/application-structure): Structure your LangGraph applications
- [LangGraph runtime](https://docs.langchain.com/oss/python/langgraph/pregel): Understand the LangGraph runtime

## Deployment & Operations

- [LangSmith Deployment](https://docs.langchain.com/oss/python/langgraph/deploy): Deploy LangGraph applications to LangSmith
- [Run a local server](https://docs.langchain.com/oss/python/langgraph/local-server): Run a LangGraph server locally
- [LangSmith Observability](https://docs.langchain.com/oss/python/langgraph/observability): Monitor and trace LangGraph applications
- [LangSmith Studio](https://docs.langchain.com/oss/python/langgraph/studio): Debug and visualize LangGraph applications
- [Agent Chat UI](https://docs.langchain.com/oss/python/langgraph/ui): Build chat interfaces for your agents
- [Test](https://docs.langchain.com/oss/python/langgraph/test): Test your LangGraph applications

## Tutorials

- [Build a custom RAG agent with LangGraph](https://docs.langchain.com/oss/python/langgraph/agentic-rag): Build a retrieval-augmented generation agent
- [Build a custom SQL agent](https://docs.langchain.com/oss/python/langgraph/sql-agent): Build an agent that queries databases

## Reference

- [Case studies](https://docs.langchain.com/oss/python/langgraph/case-studies): Real-world LangGraph implementations
- [Changelog](https://docs.langchain.com/oss/python/langgraph/changelog-py): Python package changelog

## Errors

- [GRAPH_RECURSION_LIMIT](https://docs.langchain.com/oss/python/langgraph/errors/GRAPH_RECURSION_LIMIT): Graph exceeded maximum recursion depth
- [INVALID_CHAT_HISTORY](https://docs.langchain.com/oss/python/langgraph/errors/INVALID_CHAT_HISTORY): Invalid chat history format
- [INVALID_CONCURRENT_GRAPH_UPDATE](https://docs.langchain.com/oss/python/langgraph/errors/INVALID_CONCURRENT_GRAPH_UPDATE): Concurrent graph update conflict
- [INVALID_GRAPH_NODE_RETURN_VALUE](https://docs.langchain.com/oss/python/langgraph/errors/INVALID_GRAPH_NODE_RETURN_VALUE): Invalid return value from graph node
- [MISSING_CHECKPOINTER](https://docs.langchain.com/oss/python/langgraph/errors/MISSING_CHECKPOINTER): Checkpointer required but not configured
- [MULTIPLE_SUBGRAPHS](https://docs.langchain.com/oss/python/langgraph/errors/MULTIPLE_SUBGRAPHS): Multiple subgraphs error
