Function hostnameLabelFromSandboxId

packages/worker-utils/src/hostname-label.ts:141–156

(sandboxId: string)

  }

  const legacyUserIdBytes = base64urlToBytesOrNull(sandboxId);
  if (!legacyUserIdBytes || legacyUserIdBytes.length === 0) return null;

  const label = `u-${bytesToBase32Hex(legacyUserIdBytes)}`;
  if (label.length > MAX_HOSTNAME_LABEL_LENGTH) return null;
  return label;
}

/**
 * Reverse of `hostnameLabelFromSandboxId`: parse a hostname label back
 * into its sandboxId, returning `null` if the label doesn't match either
 * scheme.
 *
 * Used by the host-based router in a follow-up PR to resolve
 * `<label>.kiloclaw.ai` to the owning Instance DO.
 */
export function sandboxIdFromHostnameLabel(label: string): string | null {
  const normalized = label.toLowerCase();
  const instanceMatch = INSTANCE_LABEL_RE.exec(normalized);