LangGraph¶
Five weeks on LLM work as a state machine: nodes are functions, edges are control flow, state is the request-scoped object you already thread through a saga.
Start this track only if state machines, retries, persistence, idempotency, and the course prerequisites are familiar.
Scope: get the state-machine idea, build a resumable graph, then use the official docs to go further. Read the framework track guide before starting.
Use a graph when you need branches, retries, pause-for-a-human, or replay. Three sequential calls do not need a graph.
| Week | Idea | You are done when… |
|---|---|---|
| 1 — Graphs | StateGraph, reducers, a graph that branches. |
Two inputs take different visible paths through the graph. |
| 2 — Workflows | Conditional edges, fan-out, subgraphs. | Parallel branches join into one validated state. |
| 3 — Persistence | Checkpoints. Replay after a crash. | A failed run resumes without repeating completed pure work. |
| 4 — Human in the loop | Interrupt, resume, the approval node. | Approve, reject, and needs-info follow distinct tested paths. |
| 5 — Don’t charge twice | Resume is at-least-once. Keys make effects once. | Replaying the side-effect node produces one charge. |
Think of it like… CI, Redux, or a workflow engine
The runtime owns the state so you can stop in the middle and start again. That is the product feature. Pretty diagrams are a side effect.