diff --git a/index.html b/index.html
index e2a8502..bb4b2ad 100644
--- a/index.html
+++ b/index.html
@@ -3,9 +3,21 @@
 <head>
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width,initial-scale=1">
-<title>vibegif</title>
+<title>vibegif · <!--count--> free public domain gifs and animated webp</title>
 <link rel="icon" type="image/webp" href="/favicon.webp">
-<meta name="description" content="public domain gallery of <!--count--> gifs and animated webp">
+<link rel="canonical" href="https://vibegif.direct-img.link/">
+<meta name="description" content="public domain gallery of <!--count--> gifs and animated webp, free to use and hot link (CC0)">
+<meta name="robots" content="max-image-preview:large">
+<meta property="og:type" content="website">
+<meta property="og:site_name" content="vibegif">
+<meta property="og:url" content="https://vibegif.direct-img.link/">
+<meta property="og:title" content="vibegif · <!--count--> free public domain gifs and animated webp">
+<meta property="og:description" content="public domain gallery of <!--count--> gifs and animated webp, free to use and hot link (CC0)">
+<meta property="og:image" content="https://vibegif.direct-img.link/og.png">
+<meta property="og:image:width" content="1200">
+<meta property="og:image:height" content="630">
+<meta name="twitter:card" content="summary_large_image">
+<!--ld-->
 <script>try{localStorage.bg&&document.documentElement.classList.add("dark")}catch{}</script>
 <style>
 :root{--bg:#fff;--fg:#000;--mute:#888}
diff --git a/public/404.html b/public/404.html
new file mode 100644
index 0000000..25645d6
--- /dev/null
+++ b/public/404.html
@@ -0,0 +1,25 @@
+<!doctype html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width,initial-scale=1">
+<title>not found · vibegif</title>
+<meta name="robots" content="noindex">
+<link rel="icon" type="image/webp" href="/favicon.webp">
+<script>try{localStorage.bg&&document.documentElement.classList.add("dark")}catch{}</script>
+<style>
+:root{--bg:#fff;--fg:#000;--mute:#888}
+.dark{--bg:#000;--fg:#fff;--mute:#777}
+@font-face{font-family:"Stain";src:url("https://cdn.jsdelivr.net/gh/multipleof4/stain.otf@master/dist/Stain.otf") format("opentype");font-display:swap}
+body{background:var(--bg);color:var(--fg);font-family:"Stain",sans-serif;text-align:center;margin:0;padding:15vh 16px}
+h1{font-weight:400;font-size:clamp(22px,5vw,44px);margin:16px 0}
+a{color:var(--mute);font-size:clamp(16px,3vw,22px)}
+a:hover{color:var(--fg)}
+</style>
+</head>
+<body>
+<img src="/ghost/float.webp" width="180" height="180" alt="ghost float">
+<h1>nothing here</h1>
+<a href="/">back to the gallery</a>
+</body>
+</html>
diff --git a/public/og.png b/public/og.png
new file mode 100644
index 0000000..1e7011e
Binary files /dev/null and b/public/og.png differ
diff --git a/public/robots.txt b/public/robots.txt
new file mode 100644
index 0000000..caaf904
--- /dev/null
+++ b/public/robots.txt
@@ -0,0 +1,4 @@
+User-agent: *
+Allow: /
+
+Sitemap: https://vibegif.direct-img.link/sitemap.xml
diff --git a/vite.config.js b/vite.config.js
index 0c89f3d..82ac522 100644
--- a/vite.config.js
+++ b/vite.config.js
@@ -4,13 +4,16 @@
 // hand-made files that have no gen file go in the first section
 // only files inside a subject folder are tiles, so root files like favicon.webp stay out
 // tile images get ?v=<hash> so browsers drop old copies when a file changes, links stay clean for hotlinking
+// <!--ld--> gets CC0 license data for every tile image, so image search can list them under creative commons
+// and the build writes sitemap.xml with the page and its tile images (google reads up to 1000 images per page)
 import{readdirSync as rd,readFileSync as rf}from'fs'
 import{createHash}from'crypto'
+const site='https://vibegif.direct-img.link',cc0='https://creativecommons.org/publicdomain/zero/1.0/'
 const sections=['bw','color','anime','manga','mini','minicolor']
 const hidden=['cat/tail.gif']  // same drawing as cat/wag.gif, kept so old links still work
 const walk=d=>rd(d,{withFileTypes:true}).flatMap(e=>e.isDirectory()?walk(`${d}/${e.name}`):`${d}/${e.name}`)
 const dims=(b,x)=>x=='gif'?[b.readUInt16LE(6),b.readUInt16LE(8)]:[b.readUIntLE(24,3)+1,b.readUIntLE(27,3)+1]
-const gallery=()=>{
+const tiles=()=>{
   const sec={},g=Object.fromEntries(sections.map(s=>[s,{}]))
   for(const f of walk('gen').filter(f=>f.endsWith('.js'))){const[,s,...r]=f.split('/');sec[r.join('/').slice(0,-3)]=s}
   for(const f of walk('public').filter(f=>/^public\/[^/]+\/.+\.(webp|gif)$/.test(f)).sort()){
@@ -18,12 +21,28 @@ const gallery=()=>{
     if(!hidden.includes(p))(g[sec[id]??sections[0]][id]??={})[x]=f
   }
   return sections.map(s=>Object.entries(g[s]).map(([id,fm])=>{
-    const x=fm.webp?'webp':'gif',b=rf(fm[x]),[w,h]=dims(b,x),v=createHash('md5').update(b).digest('hex').slice(0,8)
-    const links=['webp','gif'].filter(k=>fm[k]).map(k=>`<a href="/${id}.${k}">${k}</a>`).join(' ')
-    return`<figure><a href="/${id}.${x}"><img src="/${id}.${x}?v=${v}" alt="${id.replace('/',' ')}" width="${w}" height="${h}" loading="lazy" decoding="async"></a><figcaption>${links}</figcaption></figure>`
-  }).join('\n')).filter(Boolean).join('\n<hr>\n')
+    const x=fm.webp?'webp':'gif',b=rf(fm[x]),[w,h]=dims(b,x)
+    return{id,fm,x,w,h,src:`/${id}.${x}?v=${createHash('md5').update(b).digest('hex').slice(0,8)}`}
+  }))
 }
-export default{plugins:[{name:'gallery',transformIndexHtml:h=>{
-  const g=gallery()
-  return h.replace('<!--gallery-->',g).replaceAll('<!--count-->',g.split('<figure>').length-1)
-}}]}
+const figure=t=>{
+  const links=['webp','gif'].filter(k=>t.fm[k]).map(k=>`<a href="/${t.id}.${k}">${k}</a>`).join(' ')
+  return`<figure><a href="/${t.id}.${t.x}"><img src="${t.src}" alt="${t.id.replace('/',' ')}" width="${t.w}" height="${t.h}" loading="lazy" decoding="async"></a><figcaption>${links}</figcaption></figure>`
+}
+const ld=all=>`<script type="application/ld+json">${JSON.stringify({'@context':'https://schema.org','@graph':
+  all.map(t=>({'@type':'ImageObject',contentUrl:site+t.src,license:cc0,acquireLicensePage:site+'/'}))})}</script>`
+const sitemap=all=>`<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:image="http://www.google.com/schemas/sitemap-image/1.1">
+<url><loc>${site}/</loc><lastmod>${new Date().toISOString().slice(0,10)}</lastmod>
+${all.map(t=>`<image:image><image:loc>${site+t.src}</image:loc></image:image>`).join('\n')}
+</url>
+</urlset>
+`
+export default{plugins:[{name:'gallery',
+  transformIndexHtml:h=>{
+    const s=tiles(),all=s.flat()
+    return h.replace('<!--gallery-->',s.map(ts=>ts.map(figure).join('\n')).filter(Boolean).join('\n<hr>\n'))
+      .replace('<!--ld-->',ld(all)).replaceAll('<!--count-->',all.length)
+  },
+  generateBundle(){this.emitFile({type:'asset',fileName:'sitemap.xml',source:sitemap(tiles().flat())})}
+}]}