fix: recover failed banner cover previews

index.tsx

@@ -2,6 +2,23 @@ import React from 'react';
 import ReactDOM from 'react-dom/client';
 import App from './App';
 
+// Covers uploaded to Bunny Storage are normally served directly by its CDN.
+// If that CDN URL is unavailable in a browser, retry the safe Academy proxy.
+// This also protects previews in administrative screens that render native img
+// elements (for example a homepage-banner preview).
+document.addEventListener('error', (event) => {
+  const image = event.target;
+  if (!(image instanceof HTMLImageElement) || image.dataset.coverFallbackApplied === 'true') return;
+  try {
+    const filename = new URL(image.currentSrc || image.src, window.location.origin).pathname.split('/').pop() || '';
+    if (!/^[0-9a-f]{8}-[0-9a-f-]{27}\.(?:jpg|png|webp)$/i.test(filename)) return;
+    image.dataset.coverFallbackApplied = 'true';
+    image.src = `${import.meta.env.VITE_API_URL || '/api/v1'}/courses/covers/${filename}`;
+  } catch {
+    // Keep the browser's normal failed-image behavior for non-cover assets.
+  }
+}, true);
+
 const rootElement = document.getElementById('root');
 if (!rootElement) {
   throw new Error("Could not find root element to mount to");