Fix robots.txt, minified assets and dead links in the preview build (#3079)

preview/pages/markdown.astro

@@ -1,5 +1,7 @@
 ---
+// Legacy alias kept for old bookmarks and the downloadable package: the page
+// moved to prose.html.
 import RedirectLayout from '@shared/layouts/RedirectLayout.astro'
 ---
 
-<RedirectLayout />
+<RedirectLayout url="/prose.html" />

preview/pages/robots.txt.ts

@@ -3,15 +3,17 @@ import { site } from '@shared/lib/site'
 
 export const prerender = true
 
-// development, and crawling is allowed only in the preview environment.
+// Vercel sets VERCEL_ENV to "production" on preview.tabler.io and to "preview"
+// on branch deploys; it is unset locally. Only production may be crawled,
+// and the sitemap URL is absolute outside development.
 export const GET: APIRoute = () => {
   const environment = process.env.NODE_ENV || 'production'
+  const isProduction = process.env.VERCEL_ENV === 'production'
   const sitemapBase = environment !== 'development' ? site.previewUrl : ''
   const body = `Sitemap: ${sitemapBase}/sitemap.xml
 
-
 User-agent: *
-Disallow:${environment === 'preview' ? '' : ' /'}
+Disallow:${isProduction ? '' : ' /'}
 `
 
   return new Response(body, {

preview/pages/sitemap.xml.ts

@@ -3,7 +3,9 @@ import { site } from '@shared/lib/site'
 
 export const prerender = true
 
-// Index pages collapse to directory URLs (build.format 'file').
+// build.format 'file' emits x/index.astro as x.html (the hosting serves no
+// x/ directory), so nested index pages collapse to that file; the root index
+// stays "/".
 const pages = import.meta.glob('./**/*.astro')
 
 const urls = Object.keys(pages)
@@ -16,7 +18,7 @@ const urls = Object.keys(pages)
   })
   .map((path) => {
     if (path === 'index.html') return '/'
-    if (path.endsWith('/index.html')) return `/${path.slice(0, -'index.html'.length)}`
+    if (path.endsWith('/index.html')) return `/${path.slice(0, -'/index.html'.length)}.html`
     return `/${path}`
   })
 

preview/pages/tour.astro

@@ -18,7 +18,7 @@ import Icon from '@ui/Icon.astro'
       <Card>
         <CardHeader title="Product Tour Example">
           <CardActions>
-            <Button id="start-tour" text="Start Tour" icon="play" color="primary" element="button" />
+            <Button id="start-tour" text="Start Tour" icon="player-play" color="primary" element="button" />
           </CardActions>
         </CardHeader>
         <CardBody>