/** Classify authoritative rejection separately from temporary server failures.
 * @param {number} status HTTP response status.
 */
export function sessionResponseState(status) {
  if (status === 401 || status === 403) return 'revoked';
  return status >= 200 && status < 300 ? 'valid' : 'unavailable';
}

/** Milliseconds before each retry; attempt zero is the immediate first retry.
 * @param {number} attempt Zero-based retry index.
 */
export function sessionRetryDelay(attempt) {
  return [0, 3000, 10000, 15000][attempt] ?? 30000;
}