astro.config.mjs

import { defineConfig } from 'astro/config';
import sitemap from '@astrojs/sitemap';

// Absolute site URL is required for canonical/hreflang/OG tags and the
// generated sitemap. Override via the PUBLIC_SITE_URL environment variable
// per environment (local, deploy preview, production).
const siteUrl = process.env.PUBLIC_SITE_URL ?? 'https://matecode.dev';

export default defineConfig({
  site: siteUrl,
  output: 'static',
  trailingSlash: 'never',
  build: {
    // Emit `dist/en.html` instead of `dist/en/index.html`. With the default
    // directory format, Netlify's Pretty URLs sees a directory and issues a
    // `301 /en -> /en/`, which contradicts `trailingSlash: 'never'`: the
    // sitemap and canonical both declare the slash-less `/en`, so a crawler
    // fetching it is redirected to a page whose canonical points back at the
    // redirecting URL. File format serves `/en` directly with a 200 and keeps
    // canonical, sitemap, and hosting in agreement.
    format: 'file',
  },
  integrations: [
    sitemap({
      // File-based i18n (design.md "Decision: File-based i18n, no /es"):
      // `/` (no prefix) is the default locale and gets its own hreflang
      // alternates alongside `/en/*` — see specs/seo-geo/spec.md
      // "Localized Sitemap and Robots".
      // Generic language codes, deliberately not region-qualified. `es-ES`
      // targets Spain alone, which excludes the Latin American audience this
      // site is written for, and it contradicts the plain `hreflang="es"` the
      // pages themselves declare in BaseLayout. Two conflicting codes for one
      // cluster leave Google without a clean locale match.
      i18n: {
        defaultLocale: 'es',
        locales: {
          es: 'es',
          en: 'en',
        },
      },
      // Excludes the Netlify Forms confirmation pages from the sitemap —
      // they are transactional, not marketing routes, and are already
      // excluded from indexing via BaseLayout's `noindex` prop.
      filter: (page) => !page.includes('/gracias') && !page.includes('/thank-you'),
    }),
  ],
});