sometimes it is possible to solve a puzzle without promoting the piece (example lishogi.org/training/JcoEz ). The current algorithm marks such move as false move. Maybe it can be changed by
by the rule "under-promotion is allowed if the number of moves till mate is not increased."
I assume the change is not trivial because this could lead to two distinct variants (silver general -> gold general) and the overall design of the puzzles is based on the 'there is only one move' rule.
Thanks for leading me to the existing issue on Github's issue tracker.
A compromise between both opinions about this topic could be the automated conversion of the piece if the user selected not to promote. This shows the user which is the (more) desired variant.
If you are talking about auto promotion (like lichess has auto queening), it was referred to and is probably related to this GitHub issue github.com/WandererXII/lishogi/issues/246
You can't post in the forums yet. Play some games!