This is cool! One question: is the format documented anywhere, or a stable enough schema that someone could write, for example, a script that pulls last week's jots into a review? Having an implied contract that the format won't change as opposed to a JSON that just happens to be inspectable today would be more compelling I feel.

Fair distinction, and today it's the latter: a plain JSON array of {id, text, createdAt} that's inspectable but not yet a promised contract.