It referred to me by my login name on the AI site rather than the name it would have used if it actually found my website, so I think it was more logic than an actual identification, but it had clearly corrupted the search enough to no longer be a valid test.

Which does make me wonder about the original article; if the AI has in context any sort of clue that the user is "Kelsey Piper" (a memory of their name, a username of kpiper or kelseyp, etc.), that will radically tip the balance in favor of the AI guessing that way just by the nature of LLMs. That is to say, it highly increases the odds of that guess even if it's wrong.

Even if that is the case, though, the general identifiability of writing remains true. It's been shown for a while with techniques a lot less powerful than a frontier LLM.

It's a lossy representation