A --since:29e50ad Stryker pass found real gaps, all inside this cut's own
files:
- vertex-placement and normals fixtures anchored a vertex at the world
origin, so a mutated (+ instead of -) or dropped cellSize multiply was
invisible against a zero operand; moved them off the origin;
- the cube normals test only checked length, and three orthogonal
+-2-length face contributions summed to the same length no matter which
one a mutant negated; now checks the exact expected direction per vertex;
- the open-boundary rule only had an X-axis test, leaving TryGetQuadCells's
Y- and Z-axis guards (and TryGetOtherEndpoint's Y/Z cases) uncovered;
added the Y- and Z-axis twins of the existing plane test;
- the 1e-20 near-zero-delta fallback in Interpolate was never exercised;
added a fixture with an edge delta of ~3e-21;
- CultGeometryGridEdge's Equals and ToString had no direct test.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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