Command

Command packages a graph state update with execution control. A node can return it to write an update and route to one or more nodes, including a parent graph or a node receiving an explicit Send payload.

new Command<Resume = unknown, Update extends Record<string, unknown> = Record<string, unknown>, Nodes extends string = string>(args: Omit<CommandParams<Resume, Update, Nodes>, "lg_name">)

A Command<Resume, Update, Nodes> instance that carries state updates and/or graph control instructions.

import { Annotation, Command, StateGraph, START, END } from "@langchain/langgraph";

const State = Annotation.Root({
  value: Annotation<number>(),
  next: Annotation<string>(),
});

const route = (state: typeof State.State): Command<"finish"> => {
  if (state.value > 0) {
    return new Command({ update: { next: "finish" }, goto: "finish" });
  }
  return new Command({ update: { next: "finish" }, goto: END });
};

const finish = (state: typeof State.State) => ({
  value: state.value + 1,
});

const graph = new StateGraph(State)
  .addNode("route", route)
  .addNode("finish", finish)
  .addEdge(START, "route")
  .addEdge("finish", END)
  .compile();

await graph.invoke({ value: 1, next: "" });

The node returns a Command that updates state and selects the next destination in one result.