/**
 * Server-side code (e.g. server actions) cannot use relative fetch URLs; prefix with the app origin.
 */
export function resolveInternalFetchUrl(url: string): string {
  if (typeof window !== "undefined") return url;
  if (url.startsWith("http://") || url.startsWith("https://")) return url;
  if (!url.startsWith("/")) return url;
  const base =
    process.env.NEXT_PUBLIC_APP_URL?.replace(/\/$/, "") ??
    `http://127.0.0.1:${process.env.PORT ?? "3000"}`;
  return `${base}${url}`;
}