Source Authorship Forensics
A source-level read of op12no2/lozza, contrasted with Stockfish.
Lozza is a long-running, single-author JavaScript engine by a well-known author in the JS-chess niche. The history is a continuous stream of incremental, expertly-motivated commits — NNUE accumulator work, lazy/fused evaluation, datagen — each carrying a bench node count. It is deliberately pure JavaScript (no WASM/Emscripten), so the code stays readable.
No AI residue of any kind. Just sustained, knowledgeable engine development in the open.
Confidence: High — a mature, personal, incrementally-developed project.
Incremental, expert, and unmistakably a person's ongoing project.
| # | Signal | What it shows | Weight |
|---|---|---|---|
| 1 | 131 single-author commits with bench fingerprints (e.g. bench unchanged 613926) | OpenBench-style testing discipline | Decisive |
| 2 | Expert NNUE work: lazy/fused accumulators, 16-bit accs, add datagen command | Hands-on neural-eval engineering | Strong |
| 3 | Deliberate pure-JS, no-WASM design for readability; web-worker deployable | A considered personal engineering stance | Strong |
| 4 | Zero AI residue or agent artifacts | No generated-code fingerprints | Support |
| Where it resembles Stockfish |
|---|
| NNUE evaluation with incrementally-updated accumulators |
| Alpha-beta search with the standard modern pruning/ordering |
| Bench-in-commit testing culture |
| Datagen for self-play network training |
| Where it differs |
|---|
| Pure JavaScript (no WASM) vs C++ — readable, browser-deployable |
| One veteran author vs a global team |
| Runs in a web worker in the browser as well as via Node |
| Smaller scale, but a mature codebase |
Lozza is a human-written engine by a veteran developer — a mature, pure-JavaScript NNUE engine maintained through a long stream of incremental, bench-tested commits. It sits comfortably on the human side of the series, and stands out for proving a strong engine can be written in readable, dependency-light JavaScript.