Uses one principal line for the full-game pass, reuses the next position instead of searching played moves twice, and keeps the engine cache warm between games. Disable it to apply the selected MultiPV to every position; live puzzles still evaluate up to four branches.

The bundled opening catalog runs out where names run out. This asks Lichess how often each position and move actually occurs, so book detection follows a line as far as it is really played, and opening moves get popularity and scoring notes. Answers are cached, and analysis carries on unchanged if Lichess can't be reached.

Adds a short explanation of the line from Wikibooks' Chess Opening Theory to opening moves in the review screen, credited and linked as its CC BY-SA licence requires. Fetched only for the move you are looking at, then cached.

Point to a stronger build (e.g. an NNUE stockfish-nnue-16-single.js) you host to upgrade strength.