thought that won’t leave me alone. a page can carry two layers of text now, one for people and one for crawlers, and an ai reading that page doesn’t tell display: none from a headline. it takes the dom, comments and hidden blocks included.

old seo spam did this to fool search engines and google eventually learned to punish it. agents haven’t learned anything yet. a hidden line dressed up as normal page content can just redirect the thing reading it.

the legitimate version is genuinely useful. put a clean plain-text or json summary of your product in an invisible block, prices, availability, whatever, and let bots parse that instead of guessing from your markup. better extraction, ui untouched.

the weird version is messages left for somebody else’s agent. a watermark that flags the reader instead of the author.

the defense is obvious and nobody will pay for it: render the page, take only the visible text. that’s a browser per url instead of a fetch, which costs real money, so most crawlers will keep eating whatever you put in there.