LangGraph in Production: The WitUS Triage Agent

by bam

Build a real production LangGraph agent, one small piece at a time. You start by learning when a linear chain has outgrown itself and you actually need a graph, then design a clean state contract, wire typed tools, and add a durable human-in-the-loop approval gate with interrupt() and a Postgres checkpointer. The second module crashes the process on purpose to prove the gate survives a restart, and shows the two rules that keep your own interrupts correct. It's grounded in the open-source WitUS Triage Agent code, TypeScript first with a Python durability track. Written to code along.