Monitoring Reader in production

async function streamUsageHistory(since: Date) {
  let skip = 0;
  const limit = 100;
  while (true) {
    const envelope = await reader.request(
      "GET",
      `/v1/usage/history?skip=${skip}&limit=${limit}`,
    );
    for (const entry of envelope.data) {
      if (new Date(entry.createdAt) < since) return;
      yield entry;
    }
    if (!envelope.pagination.hasMore) return;
    skip += limit;
  }
}

const { balance, limit, used, tier, resetAt } = await reader.getCredits();
metrics.gauge("reader.credits.balance", balance);
metrics.gauge("reader.credits.used", used);

async function trackedRead(params) {
  const start = Date.now();
  let status = "success";
  let code = null;

  try {
    const result = await reader.read(params);
    return result;
  } catch (err) {
    status = "error";
    code = err.code ?? "unknown";
    throw err;
  } finally {
    const duration = Date.now() - start;
    metrics.timing("reader.read.duration", duration, { status });
    metrics.increment("reader.read.requests", { status, code });
  }
}

const res = await fetch(url, { ... });
const requestId = res.headers.get("x-request-id");
log.info({ requestId, url, status: res.status }, "reader request");