async function fetchCover(query, targetEl) {
  try {
    // In production, this should hit our /api/cover to avoid CORS and add caching,
    // but for the mockup functionality we can use iTunes directly if we don't have backend running.
    // The spec mentioned using server for CORS, but browser often allows GET to iTunes.
    // We will use the backend route to be safe.
    
    // For now, simple fallback to iTunes directly if backend is missing.
    let url = `/api/cover?q=${encodeURIComponent(query)}`;
    
    // Temporary direct fetch for local testing if no backend
    if (window.location.protocol === 'file:') {
       url = `https://itunes.apple.com/search?term=${encodeURIComponent(query)}&media=music&entity=song&limit=1`;
    }

    const r = await fetch(url);
    if (!r.ok) throw new Error('fetch error');
    
    const data = await r.json();
    let src = '';
    
    if (data.url) { // our api
      src = data.url;
    } else if (data.results && data.results[0] && data.results[0].artworkUrl100) { // direct itunes
      src = data.results[0].artworkUrl100.replace('100x100bb', '300x300bb');
    }
    
    if (src) {
      targetEl.innerHTML = `<img src="${src}" alt="cover" loading="lazy">`;
    }
  } catch (e) {
    console.error('Cover fetch failed', e);
  }
}

window.fetchCover = fetchCover;