Fixed — and thank you, this was a good catch.
I reproduced it exactly as you described. The cause: the stack menu was opening
in the same layer the game uses for its own prompts, and that layer only holds
one thing at a time. So opening it silently replaced your pending choice. That's
why "Back to Choice" took you to the stack (the menu had become the layer's
content), and why closing it with Cancel left the game waiting forever for an
answer that no longer existed anywhere. Sorry you had to abandon that game.
Two things changed. The stack menu now opens on its own layer, so it can never
sit on top of a pending choice again. And because you were right that this
smelled like a broader problem with preserving pending-choice state, there's now
a safety net underneath: the game keeps track of which prompt it's waiting for,
and if that prompt ever disappears from the screen for any reason, it comes
back on its own within a second. So even if some other path has the same flaw,
it can no longer soft-lock a game.
Going up today. If you want to know when it's live — and it's the easiest place
to report anything else you run into — the Discord is here:
Keep the reports coming, they're genuinely useful.