export function buildMessengerBotStartUrl(baseUrl: string, email: string) {
  const normalizedEmail = email.trim().toLowerCase();
  if (!baseUrl || !normalizedEmail) {
    return '';
  }

  const payload = encodeURIComponent(`login:${normalizedEmail}`);
  const separator = baseUrl.includes('?') ? '&' : '?';
  return `${baseUrl}${separator}start=${payload}`;
}