‹ All demos
LangGraph: wire the agent
A puzzle game. Connect the arrows between an agent’s steps, run the tests, and learn how LangGraph agents loop, stop and wait for people.
GoalThe bot should reply once, then stop.
Connect the arrows
After chatbot, after it replies, go to:
Pick a target for every arrow to run the tests.
How it works
- 1LangGraph builds an AI app as a graph: steps (nodes) that share one state, joined by arrows (edges). Some arrows depend on what just happened.
- 2Each level leaves some arrows open. Pick where they go, then run the tests — you watch every test walk through your graph.
- 3Four levels, four patterns: a plain graph, a tool loop, a retry limit, and pausing for a person’s approval.
- 4No AI model is called. The steps are tiny bits of code, so the game is about the graph itself — which is exactly what LangGraph adds.
More demos
All demosLiveDatabases · Built from scratch
QueryLite: a SQL database
A SQL database written from scratch — parser, B+ tree indexes, a query planner, joins and transactions — running live on 22,000 rows in your browser.
Try it
LiveDistributed systems · Built from scratch
Raft consensus, live
The algorithm that keeps etcd and Kubernetes consistent. Five servers elect a leader and replicate a log — crash them and split the network while it runs.
Try it
LiveReal-time · Built from scratch
Live collaborative editor
Real-time editing with no server. Three devices share a note — take one offline, edit everywhere, reconnect, and they merge. Open a second tab and it syncs live.
Try it