fix(layer): emit absolute sitemap URLs from configured site.url

The /sitemap.xml route resolved its base URL with `inferSiteURL()`, which
only reads environment variables (NUXT_SITE_URL, VERCEL_URL, CF_PAGES_URL,
…). A `site.url` set in nuxt.config was never consulted, so sites that
configure it the documented way fell back to `''` and emitted relative
`<loc>` values:

    <loc>/docs/getting-started/introduction</loc>

The sitemap protocol requires absolute URLs, so search engines reject these.

Expose the resolved `site.url` through `runtimeConfig.public.site` (the same
pattern already used for `mcp.route`) and prefer it in the route, keeping
`inferSiteURL()` as the fallback so env-var-only deploys are unaffected.
`withoutTrailingSlash` avoids `https://example.com//docs/...` when the
configured url ends in a slash.

Author: TerrorSquad

layer/modules/config.ts

@@ -59,6 +59,14 @@ export default defineNuxtModule({
       branch: getGitBranch(),
     })
 
+    /*
+    ** Site URL (expose to the server: /sitemap.xml needs it at runtime)
+    */
+    nuxt.options.runtimeConfig.public.site = defu(
+      nuxt.options.runtimeConfig.public.site as { url?: string } | undefined,
+      { url: (typeof nuxt.options.site === 'object' && nuxt.options.site?.url) || url },
+    )
+
     /*
     ** MCP route (expose to client so the page header dropdown stays in sync
     ** with the user-configured `mcp.route` from @nuxtjs/mcp-toolkit)

layer/server/routes/sitemap.xml.ts

@@ -1,4 +1,5 @@
 import { queryCollection } from '@nuxt/content/server'
+import { withoutTrailingSlash } from 'ufo'
 import { inferSiteURL } from '../../utils/meta'
 import { getAvailableLocales, getCollectionsToQuery, isNavigationPath } from '../utils/content'
 
@@ -9,7 +10,11 @@ interface SitemapUrl {
 
 export default defineEventHandler(async (event) => {
   const config = useRuntimeConfig(event)
-  const siteUrl = inferSiteURL() || ''
+  // Config first: inferSiteURL() only reads env vars, so a configured
+  // site.url would be dropped and every <loc> emitted relative.
+  const siteUrl = withoutTrailingSlash(
+    (config.public.site as { url?: string } | undefined)?.url || inferSiteURL() || '',
+  )
 
   const availableLocales = getAvailableLocales(config.public as Record<string, unknown>)
   const collections = getCollectionsToQuery(undefined, availableLocales)