coco_playgame/scripts/smoke-web.mjs

const base = 'http://localhost:4173/web/index.html';

const response = await fetch(base);
if (!response.ok) throw new Error(`preview page returned ${response.status}`);
const html = await response.text();
const script = html.match(/<script>([\s\S]*)<\/script>/)?.[1];
if (!script) throw new Error('missing inline game script');
new Function(script);

const assetUrls = [...html.matchAll(/'\.\.\/assets\/resources\/sprites\/([^']+)'/g)]
  .map((m) => new URL(`../assets/resources/sprites/${m[1]}`, base).href);

for (const url of assetUrls) {
  const asset = await fetch(url);
  if (!asset.ok) throw new Error(`asset failed: ${url} -> ${asset.status}`);
  const type = asset.headers.get('content-type') || '';
  if (!type.includes('image/png')) throw new Error(`asset is not png: ${url} (${type})`);
}

console.log(`web smoke passed: ${assetUrls.length} png assets loaded`);