persona-chess 0.2.4

Train lightweight chess personas from PGN files.

persona-chess

persona-chess is a Python library for training lightweight chess personas from PGN files. The goal is not to find the strongest move. The goal is to predict how a specific player is likely to move.

The current foundation includes PGN ingestion, player filtering, neural persona training, legal move masking, checkpoint inference, baseline comparison models, profile reports, JSON artifacts, and a CLI.

Install

pip install persona-chess

That single command installs the runtime stack used by the main workflow: PyTorch, Transformers, PEFT, compressed PGN support, and evaluation helpers. When training starts, persona-chess checks the selected base model in the local Hugging Face cache. If it is already present, it reuses it; if not, it downloads it once and subsequent runs use the cached copy.

CUDA is handled through PyTorch. persona-chess uses CUDA automatically when the installed PyTorch build can see a compatible GPU; otherwise it trains on CPU and prints a diagnostic message. If CUDA is requested but unavailable, the error explains whether the installed PyTorch wheel is CPU-only, whether CUDA is hidden, or whether the requested CUDA device is invalid. For NVIDIA GPUs, use the official PyTorch selector at https://pytorch.org/get-started/locally/ when you need a specific CUDA wheel. A driver that reports CUDA 13.x support can still need the CUDA wheel version currently published by PyTorch for Windows. persona-chess will not silently rewrite the user's Python environment during training; it reports the exact PyTorch/CUDA mismatch instead of guessing and installing a different wheel behind the scenes.

For local development:

pip install -e ".[dev]"

Python API

The normal workflow is train once, then load the checkpoint as a bot.

from persona_chess import PersonaChess

result = PersonaChess().train(
    "games.pgn",
    player="Target Player",
    epochs=3,          # optional
    batch_size=32,     # optional
    device="cuda",     # optional; auto uses CUDA when PyTorch can see it
)

print(result.checkpoint_dir)
print(result.model_state_path)  # .../model.pt

bot = PersonaChess.load_neural(result.checkpoint_dir)
move = bot.move("startpos")
print(move.move_uci, move.san)

By default, persona checkpoints use Maxlegrec/ChessBot as the upstream base policy. It is a MIT-licensed FEN-based Transformer chess model that predicts moves from board positions. At inference time bot.move(...) blends that base policy with the trained persona checkpoint, so the bot has a general chess prior plus the selected player's PGN style. The base model is downloaded through Hugging Face the first time it is needed after pip install persona-chess.

For large PGNs, keep the same API and switch on streaming. This writes training records under the checkpoint folder and trains batch by batch instead of keeping the whole dataset in memory:

persona = PersonaChess()
result = persona.train(
    "large-games.pgn.zst",
    player="Target Player",
    streaming=True,
    validation_ratio=0.1,
)

Baseline personas are still available for quick comparison:

from persona_chess import PersonaChess

persona = PersonaChess().fit_pgn("games.pgn", player="Target Player", model_type="blend")
persona.save("target-player.persona.json")

CLI

persona-chess profile games.pgn "Target Player"
persona-chess model-card games.pgn "Target Player" --out target-player.model-card.json
persona-chess train games.pgn "Target Player" --model-type blend --out target-player.persona.json
persona-chess move target-player.persona.json --fen "startpos"
persona-chess export-training games.pgn "Target Player" --out target-player.train.jsonl
persona-chess export-training-stream games.pgn "Target Player" --out target-player.train.jsonl
persona-chess export-base-training-stream public-games.pgn --out base.train.jsonl
persona-chess split-training-stream target-player.train.jsonl --train-out target-player.fit.jsonl --validation-out target-player.valid.jsonl
persona-chess split games.pgn "Target Player" --train-out train.jsonl --test-out test.jsonl
persona-chess benchmark games.pgn "Target Player" --model-type blend --out benchmark.json
persona-chess prepare-neural games.pgn "Target Player" --manifest-out adapter.manifest.json --move-vocab-out moves.vocab.json --position-vocab-out positions.vocab.json
persona-chess prepare-neural-stream target-player.train.jsonl "Target Player" --manifest-out adapter.manifest.json --move-vocab-out moves.vocab.json --position-vocab-out positions.vocab.json
persona-chess recommend-neural-config --training-examples 100000 --device cuda
persona-chess validate-neural adapter.manifest.json moves.vocab.json positions.vocab.json
persona-chess train-neural games.pgn "Target Player" --checkpoint-dir checkpoints/player --use-lora
persona-chess train-neural-stream target-player.train.jsonl --manifest adapter.manifest.json --move-vocab moves.vocab.json --position-vocab positions.vocab.json --checkpoint-dir checkpoints/player --init-checkpoint checkpoints/base
persona-chess neural-move checkpoints/player --fen "startpos"
persona-chess engine-move target-player.persona.json --engine-path /path/to/stockfish --fen "startpos"
persona-chess persona-report target-player.persona.json games.pgn "Target Player" --baseline-model baseline.persona.json --out persona-report.json
persona-chess download-model persona-chess/base-small --registry models.json

Built-in model backends:

• blend: weighted baseline combining exact position memory, opening book, and phase priors.
• frequency: exact position memory with global legal fallback.
• opening_book: early-game repertoire memory.
• phase: game-phase move prior for opening, middlegame, and endgame positions.

Persona Model Cards

Model cards turn a PGN collection into a portable style and data-quality report. They include style tags, move and phase breakdowns, data warnings, and a recommended inference path.

persona-chess model-card games.pgn "Target Player" --out target-player.model-card.json
persona-chess model-card games.pgn "Target Player" --format markdown --out target-player.model-card.md

Persona Evaluation

persona-report is the main product-level evaluation command. It keeps the project-specific persona metrics in persona-chess, while optionally using common scientific Python tooling through persona-chess[evaluation] when available.

The report includes move-match top-1/top-k, MRR, baseline deltas, phase metrics, piece metrics, style similarity, opening similarity, score confidence, optional SciPy distribution distances, and optional UCI-engine centipawn/blunder metrics.

persona-chess train games.pgn "Target Player" --model-type blend --out target.persona.json
persona-chess train games.pgn "Target Player" --model-type frequency --out baseline.persona.json
persona-chess persona-report target.persona.json games.pgn "Target Player" --baseline-model baseline.persona.json --out persona-report.json
persona-chess persona-report target.persona.json games.pgn "Target Player" --engine-path /path/to/stockfish --out engine-report.json

Engine-Guided Persona Moves

persona-chess can rerank persona candidates with an external UCI engine such as Stockfish or Lc0. The engine is not bundled and the persona model still supplies the candidate style; the UCI engine only acts as a quality signal.

persona-chess engine-move target-player.persona.json --engine-path /path/to/stockfish --fen "startpos" --engine-weight 0.35

Large PGN Training

For large PGN collections, use the streaming commands. They keep the training records on disk and only materialize the active batch during neural training. Input can be plain .pgn or compressed .pgn.gz, .pgn.bz2, .pgn.xz, and .pgn.zst files. Zstandard support is installed by default.

persona-chess export-training-stream games.pgn "Target Player" --out target-player.train.jsonl
persona-chess split-training-stream target-player.train.jsonl --train-out target-player.fit.jsonl --validation-out target-player.valid.jsonl
persona-chess prepare-neural-stream target-player.train.jsonl "Target Player" --manifest-out adapter.manifest.json --move-vocab-out moves.vocab.json --position-vocab-out positions.vocab.json
persona-chess train-neural-stream target-player.fit.jsonl --manifest adapter.manifest.json --move-vocab moves.vocab.json --position-vocab positions.vocab.json --checkpoint-dir checkpoints/player --validation-records target-player.valid.jsonl --use-lora

To build a general chess policy foundation before persona adaptation, export every move from a large public PGN instead of filtering by one player:

persona-chess export-base-training-stream public-games.pgn --out base.train.jsonl
persona-chess split-training-stream base.train.jsonl --train-out base.fit.jsonl --validation-out base.valid.jsonl
persona-chess prepare-neural-stream base.fit.jsonl "persona-chess-base" --manifest-out base.manifest.json --move-vocab-out base.moves.json --position-vocab-out base.positions.json --config-profile large
persona-chess train-neural-stream base.fit.jsonl --manifest base.manifest.json --move-vocab base.moves.json --position-vocab base.positions.json --checkpoint-dir checkpoints/base --validation-records base.valid.jsonl --full-finetune
persona-chess train-neural-stream target-player.fit.jsonl --manifest adapter.manifest.json --move-vocab base.moves.json --position-vocab base.positions.json --checkpoint-dir checkpoints/player --validation-records target-player.valid.jsonl --init-checkpoint checkpoints/base --use-lora

Neural preparation uses a stable chess-wide position vocabulary by default so base checkpoints and persona adapters can share the same embedding shapes. Use --data-position-vocab only for isolated experiments that will not initialize from another checkpoint.

There are two training modes:

• PersonaChess().fit_pgn(...) and persona-chess train ... fit a fast baseline persona artifact. This is the quickest way to create a playable opponent.
• export-training-stream plus prepare-neural-stream plus train-neural-stream runs the neural Transformer/LoRA path. Use this for a base model and stronger per-player adaptation.

Neural Auto Configuration

Neural commands use hardware-aware defaults when training settings are omitted. persona-chess inspects CPU memory and optional CUDA memory, then chooses a small, balanced, or large Transformer + LoRA profile. Users can still override training knobs directly:

persona-chess recommend-neural-config --training-examples 500000 --device cuda
persona-chess prepare-neural-stream target-player.train.jsonl "Target Player" --manifest-out adapter.manifest.json --move-vocab-out moves.vocab.json --position-vocab-out positions.vocab.json --config-profile balanced --epochs 3 --batch-size 32 --gradient-accumulation-steps 4
persona-chess train-neural-stream target-player.train.jsonl --manifest adapter.manifest.json --move-vocab moves.vocab.json --position-vocab positions.vocab.json --checkpoint-dir checkpoints/player --validation-records target-player.valid.jsonl --epochs 2 --batch-size 16

For very large datasets, keep the streaming path: export once, prepare the neural artifacts from JSONL, then train from the manifest. This avoids loading the full PGN or training set into memory at once.

The neural trainer reports train loss, optional validation loss, legal top-1 accuracy, legal top-3 accuracy, optimizer steps, active mixed precision mode, and trainable parameter counts. Training uses AdamW, learning-rate warmup plus cosine decay, gradient accumulation, gradient clipping, and CUDA mixed precision when available.

Long neural runs can save resumable checkpoints:

persona-chess train-neural-stream target-player.fit.jsonl --manifest adapter.manifest.json --move-vocab moves.vocab.json --position-vocab positions.vocab.json --checkpoint-dir checkpoints/player --validation-records target-player.valid.jsonl --save-best --checkpoint-every-epoch
persona-chess train-neural-stream target-player.fit.jsonl --manifest adapter.manifest.json --move-vocab moves.vocab.json --position-vocab positions.vocab.json --checkpoint-dir checkpoints/player-resumed --resume-checkpoint checkpoints/player/best

Remote base checkpoints can be distributed as zip archives through a registry JSON. Each archive must contain a checkpoint.json at or below its root.

{
  "schema_version": "persona-chess/model-registry/v1",
  "models": [
    {
      "name": "persona-chess/base-small",
      "version": "0.1.0",
      "url": "https://example.com/persona-chess-base-small.zip",
      "sha256": "..."
    }
  ]
}

Project Direction

The planned model path is:

1. A clean PGN-to-position dataset pipeline.
2. Deterministic train/test splitting at game level.
3. Strong baseline models for honest comparison.
4. A chess-native base Transformer trained on large public PGN data.
5. A training JSONL schema with legal move masks and target move indexes.
6. Per-player LoRA adapters trained from personal PGNs.
7. Legal move masking through python-chess.
8. Evaluation by move-match accuracy and style similarity metrics.

The neural command currently prepares versioned adapter manifests, move vocabularies, and position vocabularies. The package also includes an optional PyTorch Transformer policy skeleton behind the ml extra, with PEFT-powered LoRA, legal-masked policy batches, checkpoint helpers, and checkpoint inference. It is not enabled for standard installs.

License

MIT