Well I dunno, man, this looks like the sort of amusing prototype I'd expect to take a couple of days - though not to understate the value of getting it in 4 hours (and probably with less than 4 hours' continuous effort from the human). Iteration time is an important factor!

(Regarding the parting shot, I find myself once again, for the numerousth time, reminded of this curious lobsters comment that I'm having difficulty forgetting: https://lobste.rs/s/omq8rt/vibecoding_gets_emacs_patch_rejec... - perhaps not quite entirely directly germane here, I don't think, but, still, somehow, not quite entirely directly not.)