Added styling for sitemap generator

src/modules/seo/buildSitemapXml.ts

@@ -1,15 +1,27 @@
 import type { SitemapEntry } from './buildSitemapEntries.js'
 
+type BuildSitemapXmlOptions = {
+  /**
+   * URL of a CSS stylesheet to make the sitemap readable in the browser, e.g.
+   * '/sitemap.css'. Uses `type="text/css"` — the W3C "Associating Style Sheets
+   * with XML" mechanism, which is NOT deprecated (unlike XSLT / type="text/xsl",
+   * which Chrome/WebKit are removing). CSS on XML shows no warning, styles the
+   * raw tags directly (e.g. `url { display: block }` turns the wall of text into
+   * cards), and crawlers ignore the directive entirely.
+   */
+  cssUrl?: string
+}
+
 /**
  * Serializes sitemap entries to a clean, indented XML STRING — valid for crawlers
- * and readable in the browser as the native XML tree (indented, collapsible,
- * syntax-highlighted by the browser itself).
+ * and (with `cssUrl`) styled in the browser via plain CSS.
  *
- * NO XSLT stylesheet: browsers (Chrome et al.) are REMOVING XSLT support, so a
- * <?xml-stylesheet?> approach is a dead end — it shows a deprecation warning now
- * and will break soon. Instead we serve plain XML with the correct Content-Type;
- * the browser renders its built-in formatted XML view (the "code tree" look) with
- * no transformation needed.
+ * Two viewing modes:
+ *  - No cssUrl → the browser's native formatted XML tree (indented, collapsible).
+ *  - With cssUrl → a `<?xml-stylesheet type="text/css">` directive; the project's
+ *    CSS styles the XML tags (cards, labels via ::before). NOT XSLT — that's being
+ *    removed from browsers and shows a deprecation warning. CSS is safe and
+ *    W3C-standard.
  *
  *   // app/sitemap.xml/route.ts
  *   import { buildSitemapXml } from '@intecion/ipal-kit'
@@ -17,19 +29,26 @@ import type { SitemapEntry } from './buildSitemapEntries.js'
  *   export const dynamic = 'force-dynamic'
  *   export async function GET() {
  *     const entries = await sitemap()
- *     const xml = buildSitemapXml(entries)
+ *     const xml = buildSitemapXml(entries, { cssUrl: '/sitemap.css' })
  *     return new Response(xml, {
  *       headers: { 'Content-Type': 'application/xml; charset=utf-8' },
  *     })
  *   }
  *
- * The indentation makes the raw XML pleasant to read; the browser's default XML
- * viewer adds the tree/fold UI. Crawlers read the XML as usual.
+ * Put sitemap.css in the project's /public and style the tags (see docs/seo.md
+ * for a starter). Note: <loc> is an XML tag, not <a href> — CSS can't make it a
+ * clickable link (some browsers auto-detect URLs); the win is readability, not
+ * clickability.
  *
- * NOTE: if you use this custom route, DON'T also keep app/sitemap.ts — pick one
- * (this route OR the Next MetadataRoute). Two sitemaps confuse crawlers.
+ * NOTE: if you use this custom route, DON'T also keep app/sitemap.ts — pick one.
+ * Two sitemaps confuse crawlers.
  */
-export function buildSitemapXml(entries: SitemapEntry[]): string {
+export function buildSitemapXml(
+  entries: SitemapEntry[],
+  opts: BuildSitemapXmlOptions = {},
+): string {
+  const { cssUrl } = opts
+
   const esc = (s: string): string =>
     s
       .replace(/&/g, '&amp;')
@@ -46,8 +65,8 @@ export function buildSitemapXml(entries: SitemapEntry[]): string {
           e.lastModified instanceof Date ? e.lastModified.toISOString() : String(e.lastModified)
         parts.push(`    <lastmod>${esc(iso)}</lastmod>`)
       }
-      if (e.changeFrequency) {parts.push(`    <changefreq>${e.changeFrequency}</changefreq>`)}
-      if (typeof e.priority === 'number') {parts.push(`    <priority>${e.priority}</priority>`)}
+      if (e.changeFrequency) parts.push(`    <changefreq>${e.changeFrequency}</changefreq>`)
+      if (typeof e.priority === 'number') parts.push(`    <priority>${e.priority}</priority>`)
       const alternates = e.alternates?.languages
       if (alternates) {
         for (const [lang, href] of Object.entries(alternates)) {
@@ -62,8 +81,11 @@ export function buildSitemapXml(entries: SitemapEntry[]): string {
     })
     .join('\n')
 
+  const stylesheet = cssUrl ? `<?xml-stylesheet type="text/css" href="${esc(cssUrl)}"?>\n` : ''
+
   return (
     `<?xml version="1.0" encoding="UTF-8"?>\n` +
+    stylesheet +
     `<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" ` +
     `xmlns:xhtml="http://www.w3.org/1999/xhtml">\n` +
     urls +