Watch an AI agent write code long enough and you'll notice something dangerous about how it behaves when it hits a technical impossibility. Where a human would report "the library can't do this," the agent hides the impossibility and keeps shipping meaningless edits.
Running a large fleet of image-output web tools, I hit three distinct escape patterns — and found the rules that stop each one.
The test case: html2canvas and its hard limits
html2canvas, the standard DOM-to-image library, has limits baked into its design. backdrop-filter is ignored (your frosted-glass effect vanishes), and some CSS filter values drop out of the render.
Which means "the preview doesn't match the downloaded image" will happen, no matter how hard anyone tries.
