[Gambit-Checkmate]

Change

Materialize the supplied order_by directions before testing whether they are empty. A NumPy boolean array can now supply multiple directions without raising an ambiguous truth value error, and a single False direction is preserved. The existing scalar-bool reverse shorthand and empty-iterable behavior are unchanged.

Fixes #451.

Validation

• The dependency-free regression fails on develop and passes with the fix. NumPy 2.5.4 smoke tests cover multiple, single-false, and empty arrays.
• CPython 3.13.13: 3,325 tests and doctests pass with 100% coverage. The 29 focused ordering cases pass on Windows 3.11, 3.12, and 3.14. Linux 3.10 smoke passes.
• Ruff lint and formatting, mypy, chaining stub freshness, strict Sphinx, sdist/wheel builds, and git diff --check pass.

OpenAI Codex (GPT-6 based) assisted with investigation, implementation, testing, and drafting.

[coveralls]

coverage: 100.0%. remained the same — Gambit-Checkmate:fix/order-by-direction-truth-test into dgilland:develop