Hand after hand from your own deck — the reps you'd goldfish anyway, with receipts.
Call keep or mull, then see the exact line the engine found toward your goal, or
that no line exists. Or just keep dealing; judging is optional.
Agreement counts a keep as right when the engine found a line and a
mull as right when it didn't. The engine only judges goal-reachability inside three
turns — it doesn't weigh mana for the long game or what a mulligan digs into — so a
disagreement is a conversation, not a verdict.