Generate sitemap.xml at build time instead of hand-maintaining it

Derive the sitemap from the route config rather than a hand-written file: a
`buildEnd` hook writes build/client/sitemap.xml from a single PAGES map in
seo-links.ts, and the `prerender` hook cross-checks getStaticPaths() so a
prerendered page that's missing from both the sitemap and the exclude list
warns at build time.

Centralize SITE_URL and the EN<->DE page pairing in seo-links.ts so canonical,
hreflang, and the sitemap can't drift apart; the route link functions now take
a PAGES entry. Remove the now-redundant public/sitemap.xml.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Marv51

src/app/routes/home-de.tsx

@@ -1,8 +1,8 @@
 import type { Route } from "./+types/home-de";
 import { Welcome } from "../welcome/welcome";
-import { bilingualLinks } from "../seo-links";
+import { bilingualLinks, PAGES } from "../seo-links";
 
-export const links: Route.LinksFunction = () => bilingualLinks("/", "/de", "de");
+export const links: Route.LinksFunction = () => bilingualLinks(PAGES.home, "de");
 
 export function meta({}: Route.MetaArgs) {
   const title = "Marvin Rühe — Teamleitung Softwareentwicklung";

src/app/routes/home.tsx

@@ -1,8 +1,8 @@
 import type { Route } from "./+types/home";
 import { Welcome } from "../welcome/welcome";
-import { bilingualLinks } from "../seo-links";
+import { bilingualLinks, PAGES } from "../seo-links";
 
-export const links: Route.LinksFunction = () => bilingualLinks("/", "/de", "en");
+export const links: Route.LinksFunction = () => bilingualLinks(PAGES.home, "en");
 
 export function meta({}: Route.MetaArgs) {
   const title = "Marvin Rühe — Team Lead, Software Development";

src/app/routes/imprint-de.tsx

@@ -1,9 +1,8 @@
 import type { Route } from "./+types/imprint-de";
 import { Imprint } from "../imprint/imprint";
-import { bilingualLinks } from "../seo-links";
+import { bilingualLinks, PAGES } from "../seo-links";
 
-export const links: Route.LinksFunction = () =>
-  bilingualLinks("/en/imprint", "/de/impressum", "de");
+export const links: Route.LinksFunction = () => bilingualLinks(PAGES.imprint, "de");
 
 export function meta({}: Route.MetaArgs) {
   return [

src/app/routes/imprint.tsx

@@ -1,9 +1,8 @@
 import type { Route } from "./+types/imprint";
 import { Imprint } from "../imprint/imprint";
-import { bilingualLinks } from "../seo-links";
+import { bilingualLinks, PAGES } from "../seo-links";
 
-export const links: Route.LinksFunction = () =>
-  bilingualLinks("/en/imprint", "/de/impressum", "en");
+export const links: Route.LinksFunction = () => bilingualLinks(PAGES.imprint, "en");
 
 export function meta({}: Route.MetaArgs) {
   return [

src/app/seo-links.ts

@@ -1,11 +1,52 @@
-const BASE_URL = "https://ruehe.me";
+export const SITE_URL = "https://ruehe.me";
 
-export function bilingualLinks(enPath: string, dePath: string, current: "en" | "de") {
-  const canonicalPath = current === "en" ? enPath : dePath;
+export type Lang = "en" | "de";
+export type PagePair = { en: string; de: string };
+
+/**
+ * EN ↔ DE equivalents for every indexable page. Single source of truth: per-page
+ * canonical/hreflang links (`bilingualLinks`) and the generated sitemap
+ * (`renderSitemap`) both read from this, so a new page added here flows to both.
+ */
+export const PAGES = {
+  home: { en: "/", de: "/de" },
+  imprint: { en: "/en/imprint", de: "/de/impressum" },
+} as const satisfies Record<string, PagePair>;
+
+/** Canonical + hreflang alternate <link>s for one page in one language. */
+export function bilingualLinks({ en, de }: PagePair, current: Lang) {
   return [
-    { rel: "canonical", href: `${BASE_URL}${canonicalPath}` },
-    { rel: "alternate", hrefLang: "en", href: `${BASE_URL}${enPath}` },
-    { rel: "alternate", hrefLang: "de", href: `${BASE_URL}${dePath}` },
-    { rel: "alternate", hrefLang: "x-default", href: `${BASE_URL}${enPath}` },
+    { rel: "canonical", href: `${SITE_URL}${current === "en" ? en : de}` },
+    { rel: "alternate", hrefLang: "en", href: `${SITE_URL}${en}` },
+    { rel: "alternate", hrefLang: "de", href: `${SITE_URL}${de}` },
+    { rel: "alternate", hrefLang: "x-default", href: `${SITE_URL}${en}` },
   ];
 }
+
+/** The sitemap.xml document, derived from PAGES. */
+export function renderSitemap(): string {
+  const urls = Object.values(PAGES)
+    .flatMap(({ en, de }) =>
+      [en, de].map(
+        (loc) => `  <url>
+    <loc>${SITE_URL}${loc}</loc>
+    <xhtml:link rel="alternate" hreflang="en" href="${SITE_URL}${en}" />
+    <xhtml:link rel="alternate" hreflang="de" href="${SITE_URL}${de}" />
+    <xhtml:link rel="alternate" hreflang="x-default" href="${SITE_URL}${en}" />
+  </url>`,
+      ),
+    )
+    .join("\n");
+
+  return `<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
+        xmlns:xhtml="http://www.w3.org/1999/xhtml">
+${urls}
+</urlset>
+`;
+}
+
+/** Every URL listed in the sitemap (both languages), for build-time drift checks. */
+export function sitemapPaths(): string[] {
+  return Object.values(PAGES).flatMap(({ en, de }) => [en, de]);
+}

src/public/sitemap.xml

@@ -1,8 +1,38 @@
 import type { Config } from "@react-router/dev/config";
+import { writeFile } from "node:fs/promises";
+import { join } from "node:path";
+import { renderSitemap, sitemapPaths } from "./app/seo-links";
+
+// Prerendered paths intentionally kept OUT of the sitemap: the error page and
+// the two standalone app privacy policies (not part of the bilingual site).
+const SITEMAP_EXCLUDED = new Set([
+  "/404",
+  "/Project-Quick-Open/datenschutz.html",
+  "/SWR3App/datenschutz.html",
+]);
 
 export default {
-  // Config options...
-  // Server-side render by default, to enable SPA mode set this to `false`
   ssr: false,
-  prerender: true,
+  // Function form of `prerender` returns the same static paths as `true`, but
+  // also lets us cross-check route discovery against the sitemap so a new page
+  // can't silently go missing from it.
+  prerender: ({ getStaticPaths }) => {
+    const discovered = getStaticPaths();
+    const known = new Set([...sitemapPaths(), ...SITEMAP_EXCLUDED]);
+    const unaccounted = discovered.filter((path) => !known.has(path));
+    if (unaccounted.length > 0) {
+      console.warn(
+        `[sitemap] Prerendered path(s) missing from the sitemap and exclude ` +
+          `list: ${unaccounted.join(", ")}. Add them to PAGES in ` +
+          `app/seo-links.ts, or to SITEMAP_EXCLUDED in react-router.config.ts.`,
+      );
+    }
+    return discovered;
+  },
+  // Emit sitemap.xml into the prerendered output, derived from PAGES.
+  buildEnd: async ({ reactRouterConfig }) => {
+    const out = join(reactRouterConfig.buildDirectory, "client", "sitemap.xml");
+    await writeFile(out, renderSitemap(), "utf-8");
+    console.log(`[sitemap] wrote ${out}`);
+  },
 } satisfies Config;