CF Workers AI has a ~4MB JSON body limit. Large cover images base64-encoded can easily exceed this, causing Cloudflare to return a 502 Bad Gateway. Added resizeRefImage() which scales the reference down so its longest side ≤ 768px (nearest-neighbour, re-encoded as JPEG) before passing it to the GenerateImageFromReference call. Images already within the limit pass through unchanged. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>