`FLY_PROBE_CATCH=shop` drives a `BUY ...` from a checkpoint the stream looped in
and prints, per frame, what the seam reads at the counter, the halves of every
purchase's precondition, the outcome of the macro three times over, and what an
A press at the counter really opens. `screen_text` decodes the tile buffer,
because the question is which figure the game drew and the bytes that would name
it are not rewritten between two of the mart's screens.