seo(i18n): add hreflang link tags to per-page HTML head

Mlaz-code · claude · Mlaz-code · commit b20e050848ca · 2026-05-09T19:47:31.000-04:00
generateMetadata in the catch-all MDX route now emits alternates.languages
for all 4 locales plus x-default. Next.js renders these as
&lt;link rel="alternate" hreflang="..." href="..." /&gt; in each page's &lt;head&gt;,
giving Google a per-page hreflang signal in addition to the sitemap-level
alternates.

Belt-and-suspenders for SEO: search engines read both signals, but the
HTML head is the more robust source.

Co-Authored-By: Claude Opus 4.7 (1M context) &lt;noreply@anthropic.com&gt;
diff --git a/app/[lang]/[[...mdxPath]]/page.tsx b/app/[lang]/[[...mdxPath]]/page.tsx
@@ -4,15 +4,25 @@ import { ApiReferenceJsonLd, PageBreadcrumb } from '../../../components/Structur
 
 export const generateStaticParams = generateStaticParamsFor('mdxPath')
 
+const LOCALES = ['en', 'es', 'pt-BR', 'de']
+const DEFAULT_LOCALE = 'en'
+
 export async function generateMetadata(props) {
   const params = await props.params
   const { metadata } = await importPage(params.mdxPath, params.lang)
   const path = params.mdxPath ? `/${params.lang}/${params.mdxPath.join('/')}` : `/${params.lang}`
+  const subPath = params.mdxPath ? `/${params.mdxPath.join('/')}` : ''
+  const languages: Record<string, string> = {}
+  for (const l of LOCALES) {
+    languages[l] = `https://docs.sharpapi.io/${l}${subPath}`
+  }
+  languages['x-default'] = `https://docs.sharpapi.io/${DEFAULT_LOCALE}${subPath}`
   const ogTitle = metadata.title ? `${metadata.title} - SharpAPI Docs` : 'SharpAPI Docs'
   return {
     ...metadata,
     alternates: {
       canonical: `https://docs.sharpapi.io${path}`,
+      languages,
     },
     openGraph: {
       title: ogTitle,
