nuxt4-demo/app/middleware/auth.global.ts

import {
  DEFAULT_AUTHENTICATED_LANDING_PATH,
  isGuestOnlyRoute,
  isPublicRoute,
  normalizeSafeRedirect,
} from "../utils/auth-routes";
import { useAuthSession } from "../composables/useAuthSession";

export default defineNuxtRouteMiddleware(async (to) => {
  const { initialized, loggedIn, refresh } = useAuthSession();
  if (!initialized.value) {
    await refresh();
  }

  const currentPath = to.path;
  const currentFullPath = to.fullPath;
  const isLoggedIn = loggedIn.value;

  if (!isLoggedIn && !isPublicRoute(currentPath)) {
    return navigateTo({
      path: "/login",
      query: { redirect: currentFullPath },
    });
  }

  if (isLoggedIn && isGuestOnlyRoute(currentPath)) {
    const redirectCandidate = Array.isArray(to.query.redirect)
      ? to.query.redirect[0]
      : to.query.redirect;
    const redirectTarget = normalizeSafeRedirect(
      redirectCandidate,
      DEFAULT_AUTHENTICATED_LANDING_PATH,
    );

    if (redirectTarget !== currentFullPath && redirectTarget !== currentPath) {
      return navigateTo(redirectTarget);
    }
    return navigateTo(DEFAULT_AUTHENTICATED_LANDING_PATH);
  }
});