Practical TypeScript graph with an approval pause

import {
  StateGraph, StateSchema, START, END,
  MemorySaver, interrupt, Command,
} from "@langchain/langgraph";
import { z } from "zod";

const State = new StateSchema({
  claimId: z.string(),
  draftSummary: z.string(),
  approved: z.boolean().default(false),
  outcome: z.string().default("pending"),
});

const graph = new StateGraph(State)
  .addNode("prepare", (state) => ({
    draftSummary: `Review draft for claim ${state.claimId}`,
  }))
  .addNode("review", (state) => {
    // No external side effects before this pause.
    const choice = interrupt({
      action: "review_claim_draft",
      summary: state.draftSummary,
    });
    const decision = z.object({ approved: z.boolean() }).parse(choice);
    return { approved: decision.approved };
  })
  .addNode("accepted", () => ({ outcome: "ready_for_business_validation" }))
  .addNode("rejected", () => ({ outcome: "cancelled" }))
  .addEdge(START, "prepare")
  .addEdge("prepare", "review")
  .addConditionalEdges("review", (state) =>
    state.approved ? "accepted" : "rejected"
  )
  .addEdge("accepted", END)
  .addEdge("rejected", END)
  .compile({ checkpointer: new MemorySaver() });

// Demo only: production derives the thread through authorized server-side lookup.
const config = { configurable: { thread_id: "demo-claim-review-42" } };
const paused = await graph.invoke({
  claimId: "C42",
  draftSummary: "",
}, config);
console.log(paused.__interrupt__); // Display the review proposal safely.

// Simulates a person's decision. A real resume endpoint must authenticate it.
const resumed = await graph.invoke(
  new Command({ resume: { approved: true } }), config,
);
console.log(resumed.outcome); // ready_for_business_validation