# Chapter 13 LangGraph: Building Stateful Agents

> 🕸️ *"LangGraph replaces linear chains with graph structures, giving Agents true state management and complex workflow capabilities."*

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## Chapter Overview

LangGraph is the next-generation Agent framework from the LangChain team. Compared to linear Chains, LangGraph builds Agent workflows through directed graphs, natively supporting loops, conditional branching, and persistent state — exactly the capabilities needed to build complex Agent systems.

## Chapter Goals

After completing this chapter, you will be able to:

- ✅ Understand the advantages of graph structures over linear chains
- ✅ Master LangGraph's core concepts: nodes, edges, and state
- ✅ Build a Graph Agent from scratch
- ✅ Implement advanced workflows including conditional routing and loop control
- ✅ Master the Human-in-the-Loop human-AI collaboration pattern
- ✅ Build a workflow automation Agent

## Chapter Structure

| Section | Content | Difficulty |
|---------|---------|------------|
| 13.1 Why Graph Structures? | Limitations of linear chains | ⭐⭐ |
| 13.2 Core Concepts: Nodes, Edges, State | LangGraph fundamentals | ⭐⭐ |
| 13.3 Your First Graph Agent | Hands-on practice | ⭐⭐⭐ |
| 13.4 Conditional Routing and Loop Control | Advanced workflows | ⭐⭐⭐ |
| 13.5 Human-in-the-Loop | Human-AI collaboration | ⭐⭐⭐ |
| 13.6 Practice: Workflow Automation Agent | Comprehensive application | ⭐⭐⭐⭐ |

## ⏱️ Estimated Study Time

Approximately **120–150 minutes** (including hands-on exercises)

## 💡 Prerequisites

- Completed Chapter 12 LangChain fundamentals
- Basic understanding of directed graphs (nodes and edges)
- Basic Python async programming (`async/await`)

## 🔗 Learning Path

> **Prerequisites**: [Chapter 12 LangChain](../chapter_langchain/README.md)
>
> **Recommended Next**:
> - 👉 [Chapter 16 Multi-Agent Collaboration](../chapter_multi_agent/README.md) — build multi-Agent systems with LangGraph
> - 👉 [Chapters 21–23 Capstone Projects](../chapter_coding_agent/README.md) — apply LangGraph comprehensively in hands-on projects

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*Next section: [13.1 Why Graph Structures?](./01_why_graph.md)*
