from typing import TypedDict, List
from langgraph.graph import StateGraph, END
from langchain_openai import ChatOpenAI
# 1) Define State
action_token = "<act>" # simple signal for tool-use vs. final answer
class State(TypedDict):
messages: List.
- Free Intro to LangGraph course from the LangChain Academy.
- A complete video course for beginners, covering complex conversational workflows.
## Wrap-Up: From Prototype to Reliable Agents
LangGraph gives you graph-native control over LLM applications: explicit routes, resumable state, and observable behavior. Start small with a single-agent loop, then graduate to multi-agent supervisors, policy gates, and human review. Keep nodes simple, state clean, and routes deterministic.
Action steps:
- Scaffold a minimal state and two nodes (`agent`, `tool`).
- Add a router with a clear `END` path.
- Introduce checkpoints and tests before scaling up.
- Layer in tools and specialist agents as you grow.
With these foundations—and a strong debugging loop—you’ll ship agent systems that behave consistently in production.
### FAQ
Q1:What is LangGraph used for?
LangGraph is used to build reliable agent and multi-agent workflows with explicit control flow, persistent state, and checkpoints. It’s ideal for loops, tool use, human-in-the-loop steps, and complex orchestration.
Q2:How do I install and set up LangGraph?
Install with `pip install langgraph langchain` (Python) or `npm i @langchain/langgraph langchain` (JS/TS). Configure your LLM provider (e.g., `OPENAI_API_KEY`) and start by defining a `State`, nodes, and conditional edges.
Q3:Is LangGraph different from LangChain?
Yes. LangGraph is a separate package that focuses on graph-based orchestration and stateful, resumable workflows. It complements LangChain’s models, tools, and integrations, adding determinism and reliability.
Q4:Can I build multi-agent systems with LangGraph?
Absolutely. LangGraph supports supervisor–worker patterns, debate or committee agents, and policy gates. You route between agents via conditional edges and maintain shared or segmented state.
Q5:How do I prevent infinite loops in LangGraph?
Define clear termination conditions and always provide an `END` path in routers. Add loop counters or timeouts in state, prune messages, and write unit tests to verify routing logic.