[Author here] The AI feature is their implementation on the server. I was just trying to see if the same could be implemented client-side as a good use case for the, as you say, experimental, Prompt API. (It's in origin trial, so you can use it already on production sites.) Downloading a model for just this use case is obviously stretching it. You'd use it if it's there, but not download it on purpose just for this convenience.