CptKrkIsClmbngThMntn [any]

I don’t know specifically of any piece of tech that does this, but it would be very very easy to code as a plugin for a book reader app or something like that. It’d be more difficult to do well in more complicated text or mixed media, like spreadsheets, PDFs, or browser pages, since you probably don’t want every piece of text on the page to have the effect.

I find parenthesis are best when concept B is worth noting, but tangential to concept A, especially when the next few points are going to be back on the same track that A was on.