Build a chat UI on the API

curl -fsSL https://reasonmachines.com/install.sh | bash
reason login
reason connect                       # makes this computer a target

export REASON_API_KEY=reason_...

export {};

const BASE = "https://api.reasonmachines.com/v3";
const KEY = process.env.REASON_API_KEY;
if (!KEY) throw new Error("Set REASON_API_KEY first.");

type Device = {
  id: string;
  name: string;
  kind: "mac" | "headless";
  online: boolean;
  roots: { id: string; label: string }[];
};
type SessionEvent = {
  id: string;
  seq: number;
  position: number;
  type: string;
  text: string | null;
};
type EventsPage = {
  session: { status: "running" | "exit" | "error" | "suspended"; outcome: string | null };
  items: SessionEvent[];
  next_seq: number;
};

async function api<T>(path: string, init: RequestInit = {}): Promise<T> {
  const response = await fetch(`${BASE}${path}`, {
    ...init,
    headers: {
      authorization: `Bearer ${KEY}`,
      "content-type": "application/json",
      ...(init.headers as Record<string, string> | undefined),
    },
  });
  const body = await response.json().catch(() => ({}));
  if (!response.ok) {
    throw new Error(`${init.method ?? "GET"} ${path} failed: ${response.status} ${JSON.stringify(body)}`);
  }
  return body as T;
}

const { org_id: orgId } = await api<{ org_id: string }>("/self");

// 1. Pick a connected computer you own, or fall back to the cloud.
const { devices } = await api<{ devices: Device[] }>(`/organizations/${orgId}/devices?first=50`);
const computer = devices.find((device) => device.online && device.kind === "headless");
const target = computer
  ? { kind: "headless", device_id: computer.id, cwd: process.cwd() }
  : { kind: "cloud" };

// 2. Create the Session. It returns at once and runs in the background.
const created = await api<{ session_id: string; url: string }>(`/organizations/${orgId}/sessions`, {
  method: "POST",
  body: JSON.stringify({
    prompt: "Run pwd and report the result. Do not change any files.",
    target,
  }),
});
const sessionId = created.session_id;
console.log(`Session ${sessionId} on ${computer ? computer.name : "the cloud"}: ${created.url}`);

// 3. Poll events with the cursor, keeping the highest seq per event id.
async function follow(id: string): Promise<Map<string, SessionEvent>> {
  const events = new Map<string, SessionEvent>();
  let after = 0;
  let status: EventsPage["session"]["status"] = "running";
  while (status === "running") {
    const page = await api<EventsPage>(
      `/organizations/${orgId}/sessions/${id}/events?after_seq=${after}&wait_ms=20000`,
    );
    for (const event of page.items) {
      const previous = events.get(event.id);
      if (!previous || event.seq > previous.seq) events.set(event.id, event);
    }
    after = page.next_seq;
    status = page.session.status;
  }
  return events;
}

function printReplies(events: Map<string, SessionEvent>) {
  const ordered = [...events.values()].sort((a, b) => a.position - b.position);
  for (const event of ordered) {
    if (event.type === "assistant" && event.text) console.log(`\n${event.text}`);
  }
}

printReplies(await follow(sessionId));

// 4. Send a follow-up in the same Session and follow again.
await api(`/organizations/${orgId}/sessions/${sessionId}/messages`, {
  method: "POST",
  body: JSON.stringify({ message: "Now list the files in this folder." }),
});
printReplies(await follow(sessionId));