TypeScript over HTTP

There is no TypeScript client. The gateway’s API is JSON over HTTP, so fetch is enough. This file reads a record, waits where your model call would go, and appends one entry naming the version it read. Node 24 and later strip the types and run the file directly. This run used 26.7.0.

recipe.ts

const BASE = "http://127.0.0.1:8080";
const TOKEN = "rem-token";
const RECORD = "incidents/inc-21";

type Field = { value: unknown; version: number };

async function call(path: string, init: RequestInit = {}) {
  const res = await fetch(`${BASE}/v1${path}`, {
    ...init,
    headers: { Authorization: `Bearer ${TOKEN}`, "Content-Type": "application/json" },
  });
  const body = await res.json();
  if (!res.ok) throw Object.assign(new Error(body.error), body);
  return body;
}

for (;;) {
  const rec = await call(`/records/${RECORD}`);
  const plan = rec.fields.planned_action as Field;
  console.log(`read planned_action v${plan.version}: ${JSON.stringify(plan.value)}`);

  await new Promise((r) => setTimeout(r, 3000)); // your model call goes here

  try {
    await call(`/records/${RECORD}/fields/actions_taken/entries`, {
      method: "POST",
      body: JSON.stringify({
        entry: `executed: ${plan.value}`,
        evidence: "kubectl output",
        based_on: [{ field: "planned_action", version: plan.version }],
      }),
    });
    console.log("write accepted");
    break;
  } catch (e: any) {
    if (e.error !== "STALE_PREMISE") throw e;
    for (const m of e.moved) {
      console.log(`rejected: ${m.field} moved v${m.your_version} -> v${m.current_version} by ${m.current_author}`);
    }
  }
}

Run it with the gateway from Install and another agent writing planned_action. The diagnoser moved the field while this file was deciding:

read planned_action v1: "restart payments-api pods"
rejected: planned_action moved v1 -> v2 by apikey:diagnoser
read planned_action v2: "roll back api deployment"
write accepted

Three things carry that behaviour:

In the code	What it does
`plan.version` from the `get`	The version your decision is based on. Every read returns one per field.
`based_on` on the append	Declares that premise. The gateway rejects the write if the field has moved.
`e.moved` on the 409	Names each premise that moved, with the version and author that replaced it.

The Python and Go clients have a Session that remembers versions and fills in based_on for you. In TypeScript you hold them yourself, as plan.version does here. Keep them out of any framework state object that outlives one cycle, because another agent’s write makes them wrong.

Handling rejections lists the other error bodies. The HTTP API has every route and field.

OpenAI Agents SDK