fix(seo): sitemap-[lang].xml emits doubled locale prefix and broken hreflang

[JohnRDOrazio]

Symptom

app/api/sitemap/[lang]/route.ts emits malformed URLs and incorrect hreflang alternates for any locale that has Polylang-translated pages (currently affects all non-English).

For an Italian translated page like governance-2/governanza-del-progetto:

• <loc> becomes https://catholicdigitalcommons.org/it/it/governance-2/governanza-del-progetto (doubled locale).
• The <xhtml:link rel="alternate" hreflang="en" ...> is built from the same Italian-prefixed URI, so the English alternate also points to a non-existent IT URL.

Root cause

In app/api/sitemap/[lang]/route.ts:

function buildUrl(locale: string, path: string): string {
  const prefix = localePrefix(locale)
  // ...
  return `${baseUrl}${prefix}${cleanPath}`
}

for (const page of pages) {
  const uri = page.uri === '/' ? '/' : page.uri
  // ...
  entries.push(urlEntry(buildUrl(lang, uri), ..., uri))
}

page.uri from getAllPages(lang) already includes the Polylang language prefix (/it/...) in directory mode. buildUrl then prepends the prefix again. And buildAlternateLinks(uri) reuses that locale-specific URI for every hreflang, so English/Spanish/etc. alternates all point at the IT URL.

Suggested fix

Fetch and use slug (or a parent-slug chain) from WP instead of uri — same fix shape as #53. Then buildUrl(lang, '/governance-2/governanza-del-progetto') produces the right result. For hreflang alternates, you need the per-locale path (each language has its own translated slug), so either:

• query pages once per locale and build a translation map keyed by canonical post ID, or
• include translations { language { slug } slug } in the GraphQL query so a single fetch per locale carries all hreflang variants.

Notes

• GET_ALL_PAGES in lib/wordpress/queries.ts:418 returns slug and uri; only slug is needed once this is fixed.
• This affects every non-English sitemap and degrades multilingual SEO. Worth fixing before more languages are added.

Related

Same page.uri misuse as #53.