You want to bring in a dependency to avoid writing one 8 line CTE?

The number of lines needed is not a good measure for gnarliness.

(To be fair, I don't know if gnarliness is measurable at all.)

It isn’t gnarly at all, but recursive CTE are outside the experience of most SQL devs. Here “gnarly” is used to describe “unfamiliar”.

SQLite is a pretty darn good solution for any file(set) that needs atomic / consistent writes

Why not? Just add child/parent ids