v1.5.1

Package hygiene and benchmark fairness, driven by the first field reports from production use.

Changed

• The Python package is properly moduled: __init__.py (849 lines of implementation) is now a ~50-line public surface over estimators.py, _compat.py (the XGBoost translation tables), and _coerce.py. Public API unchanged (same nine names); pickles from earlier versions load bit-identically. The lite design review behind it: docs/reviews/2026-07-30-design-review-python.md.
• Benchmark harness fairness fixes (adversarial review, docs/reviews/2026-07-30-review-benchmark-fairness.md): the CatBoost borders-vs-bins fencepost now lives in one place (catboost_core, guard-tested) after call-site translations drifted three ways; XGBoost and LightGBM no longer run one bin short of bonsai in the airline and gpu-pareto suites; grinsztajn pins bonsai to the references' thread count. A rented-GPU re-check of both airline knob shapes confirmed no published cell depended on the drift (deltas within ±0.0022 of zero, all cited leads stand). The protocol page now states the classification leaf-floor caveats.

Docs

• Running the benchmarks (docs/use/benchmarks.md): the installed-wheel and source-tree paths side by side, all four suites documented (the airline ladder for the first time), and where result rows land.