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Lab 9: Patterns in LangGraph

The Big Picture Every agent pattern is just a different graph shape

🔄

ReAct Pattern

What it does

The agent thinks, acts, observes, and thinks again. It keeps looping until it has enough information to produce a final answer. This is the backbone of most reasoning agents.

Graph Structure

4 nodes + 1 conditional + loop edge

When to use

When you need an agent that can reason step-by-step and use tools dynamically to gather information.

The Loop

Think → Act → Observe → Think (repeat until done)

The Insight

🔄 ReAct
🔍 Reflection
📋 Planning
🔧 Tool Use

Every pattern is just a different arrangement of the same building blocks: Nodes, Edges, Conditional Edges, and Loops. LangGraph gives you the tools to build ANY of these and patterns that haven't been invented yet.

Node
Edge
Conditional
Loop Edge