feat: add branded 404 page

server.js

@@ -11,7 +11,7 @@ import { seedDemoMemes } from './src/seed.js';
 import { moderateImage } from './src/moderation.js';
 import { createUploadLimiter } from './src/uploadLimits.js';
 import { createIpRateLimiter } from './src/rateLimits.js';
-import { feedJson, llmsTxt, manifest, noIndex, publicBaseUrl, renderIndex, robotsTxt, sitemapXml } from './src/seo.js';
+import { feedJson, llmsTxt, manifest, noIndex, publicBaseUrl, renderIndex, renderNotFound, robotsTxt, sitemapXml } from './src/seo.js';
 
 await loadDotEnv();
 
@@ -36,6 +36,7 @@ const DISCOVERY_ROUTES = new Set([
 ]);
 const ADMIN_TOKEN = process.env.ADMIN_TOKEN || crypto.randomBytes(24).toString('hex');
 const indexTemplate = await fs.readFile('./public/index.html', 'utf8');
+const notFoundTemplate = await fs.readFile('./public/404.html', 'utf8');
 const openApiSpec = JSON.parse(await fs.readFile('./openapi.json', 'utf8'));
 const memeApiSkillTemplate = await fs.readFile('./meme-api.skill.md', 'utf8');
 
@@ -90,7 +91,9 @@ const server = http.createServer(async (req, res) => {
     const memePageMatch = url.pathname.match(/^\/meme\/([a-f0-9]{64})\/?$/);
     if (req.method === 'GET' && memePageMatch) {
       const meme = store.get(memePageMatch[1]);
-      if (!meme || meme.status !== 'approved') return sendText(res, 404, 'Not found');
+      if (!meme || meme.status !== 'approved') {
+        return sendNotFoundPage(res, { baseUrl, pathname: url.pathname });
+      }
       const nonce = crypto.randomBytes(16).toString('base64');
       withSecurityHeaders(res, { scriptNonce: nonce });
       return sendHtml(res, 200, renderIndex({
@@ -292,6 +295,9 @@ const server = http.createServer(async (req, res) => {
       return sendJson(res, 200, { ok: true });
     }
 
+    if (isBrowserPageRequest(req, url)) {
+      return sendNotFoundPage(res, { baseUrl, pathname: url.pathname });
+    }
     return sendText(res, 404, 'Not found');
   } catch (error) {
     const status = error.statusCode || 500;
@@ -323,6 +329,27 @@ function isDiscoveryRoute(req, url) {
   return DISCOVERY_ROUTES.has(url.pathname);
 }
 
+function isBrowserPageRequest(req, url) {
+  if (req.method !== 'GET') return false;
+  return ![
+    '/api',
+    '/assets',
+    '/media',
+    '/download',
+    '/admin',
+    '/admin-media'
+  ].some((prefix) => url.pathname === prefix || url.pathname.startsWith(`${prefix}/`));
+}
+
+function sendNotFoundPage(res, { baseUrl, pathname }) {
+  noIndex(res);
+  return sendHtml(res, 404, renderNotFound({
+    template: notFoundTemplate,
+    baseUrl,
+    pathname
+  }));
+}
+
 async function loadDotEnv() {
   let content = '';
   try {