Soft fails
Primarily, Chessbook is trying to make sure you play your repertoire move. If you don't play your repertoire move, it will grade whether the move you played was still a good move, via Stockfish.
| What you play | Visual result | Spaced repetition effect |
|---|---|---|
| Your repertoire move | Green tick | Recorded as correct |
| A sound move, but your repertoire continues from this position | Green “OK” | Recorded as incorrect — this is a soft fail |
| A sound move at the end of your repertoire | Green “OK” | No penalty; Chessbook still asks for your repertoire move |
| A mistake or blunder | Orange or red warning | Recorded as incorrect |
A soft fail means the move was fine as a chess move, but you didn't remember the repertoire you were trying to practice. Chessbook will ask for the repertoire move, then bring the position back later in the same session. That later retry is just extra practice and isn't recorded as another spaced repetition review.
If you want a sound alternative to count as correct, add it to your repertoire.