fix(seo): enable trailingSlash for consistent canonical/hreflang/sitemap URLs (#236)

Semrush flagged 9 hreflang conflicts because Vercel serves both /en and
/en/ as 200 (no redirect), so whichever form tags use conflicts with the
alternate crawled URL.

Fix: enable trailingSlash: true in Next.js config so Vercel redirects
/en → /en/ (308). Update page.tsx and sitemap generator to produce
trailing-slash URLs consistently across:
- <link rel="canonical">
- <link rel="alternate" hreflang>
- sitemap.xml <loc> and <xhtml:link>

Build tested locally — static export now generates directory-based
index.html files (en/index.html instead of en.html).

Co-authored-by: paperclip-resolver[bot] <3736210+paperclip-resolver[bot]@users.noreply.github.com>

Author: Mlaz-code

app/[lang]/[[...mdxPath]]/page.tsx

@@ -10,8 +10,8 @@ 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 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}`

next.config.mjs

@@ -7,6 +7,7 @@ const withNextra = nextra({
 
 export default withNextra({
   output: 'export',
+  trailingSlash: true,
   images: { unoptimized: true },
   // Nextra reads i18n config, extracts locales, then removes it (App Router compatible)
   i18n: {

scripts/generate-sitemap.mjs

@@ -64,7 +64,7 @@ async function lastmod(file) {
 }
 
 function url(locale, route) {
-  const path = route ? `/${locale}/${route}` : `/${locale}`
+  const path = route ? `/${locale}/${route}/` : `/${locale}/`
   return `${HOST}${path}`
 }