09.02 - LangGraph Nodes, Edges, And State
Learn LangGraph's core graph mental model: shared state, node functions, normal edges, conditional edges, reducers, compilation, and invocation.
The lesson builds a deterministic Python support workflow so every state update, branch, reducer, and visited path can be tested without relying on live model calls.
You'll learn:
Explain the role of state, nodes, edges, and reducers in a graph workflow
Separate node work from edge-based control flow
Use conditional edges for escalation decisions
Design append-style reducers for facts and execution history
Test graph paths, branch behavior, and loop protection
Source code and lesson materials:
https://github.com/kakatur/agentic-ai...
Chapters:
00:00 Crash Halfway Through
00:39 State Is the Contract
01:17 Nodes Do Work
01:54 Edges Control Flow
02:31 Reducers Preserve Evidence
03:12 Invoke the Graph
03:48 Test the Contract
04:19 Interview Question
04:58 Keep the Graph Boring
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