Error handling

HTTP/1.1 403 Forbidden
Content-Type: application/json

{
  "error": "Upgrade to Agency to use batch processing.",
  "requiredPlan": "agency"
}

async function callApi(url, options, attempt = 1) {
  const res = await fetch(url, options);

  // Success or non-retryable client error: return as-is.
  if (res.status < 500 && res.status !== 429) return res;

  if (res.status === 429) {
    // Two kinds of 429 aren't worth an automatic retry: the monthly API
    // cap (code "api_monthly_limit_reached", whose Retry-After counts
    // down to your cycle reset, which can be days), and the job-quota
    // and concurrent-limit 429s (no Retry-After at all).
    const body = await res.clone().json().catch(() => null);
    if (body && body.code === "api_monthly_limit_reached") return res;
    if (!res.headers.get("Retry-After")) return res;
  }

  // Give up after 5 attempts.
  if (attempt >= 5) return res;

  // Burst 429: honor Retry-After. 5xx: exponential backoff.
  const delay =
    res.status === 429
      ? Number(res.headers.get("Retry-After")) * 1000
      : Math.min(1000 * 2 ** (attempt - 1), 16_000);

  await new Promise((r) => setTimeout(r, delay));
  return callApi(url, options, attempt + 1);
}