The scorebook
The engine trains nightly by gated self-play with human-game replay, and Stockfish signs the rating. Each position is handed to the agent that owns it:
Training pipeline
Behavioural cloning on real Lichess games.
pretrain/model.ptGated self-play with human-game replay. Promoted only on a win.
posttrain/gen-*.ptThe champion, scaled to an honest rating; Stockfish grades it.
/move · /calibrateStrength over training
Each point is a checkpoint, rated by real games (brass = the per-checkpoint measurement, small-sample noise; claret = best reached). The curve is anchored so the endpoint equals the live Stockfish-calibrated rating, and nightly training appends new entries.
How the Elo is earned
Stockfish is throttled to known Elo bands and the agent plays gauntlets against each; a Bradley-Terry fit turns the scores into one calibrated rating. The agents never use Stockfish to choose a move - it only grades them.
Information theory
Which board features carry the most information about who wins - published with the analysis run.