export function isInternal(base, candidate) {
  try {
    const baseUrl = new URL(base);
    const testUrl = new URL(candidate, base);
    const protocolOk = testUrl.protocol === "http:" || testUrl.protocol === "https:";
    const stripWWW = (h) => h.replace(/^www\./i, "");
    return protocolOk && stripWWW(baseUrl.hostname) === stripWWW(testUrl.hostname);
  } catch {
    return false;
  }
}