There's a deceptively simple bug hiding in plain sight on almost every government form, university portal, and job application site: "Upload a photo under 50KB." No API, no error message explaining why, no tolerance — just silent rejection if you're 2KB over. It sounds like a trivial constraint until you actually try to satisfy it programmatically. File size in bytes isn't a variable you can set directly; it's a derived value — a function of pixel dimensions, image entropy, and compression ...