Function isTransientError

src/utils/retry.ts:98–115

(err: any)

/** Default transient classifier. */
export function isTransientError(err: any): boolean {
  if (err == null) return false;
  // Never retry a user abort.
  const msg = String(err?.message ?? err);
  if (/\baborted\b/i.test(msg) && !/aborted by the server/i.test(msg)) return false;

  const status = statusOf(err);
  if (status !== undefined) {
    // 408 Request Timeout, 409 Conflict (sometimes transient), 425 Too Early,
    // 429 Too Many Requests, and all 5xx are worth retrying. 5xx EXCEPT 501.
    if (status === 408 || status === 409 || status === 425 || status === 429) return true;
    if (status >= 500 && status !== 501) return true;
    return false; // other 4xx are permanent (400/401/403/404/422…)
  }
  // No status → look at the message/code for network-level signals.
  const code = String(err?.code ?? '');
  return TRANSIENT_CODE_RE.test(msg) || TRANSIENT_CODE_RE.test(code);
}

/**
 * Run `fn`, retrying on transient failures with full-jitter exponential