Test asserts 60 frames of indoor flat-floor walking should produce
≤5 ContactPlane writes. Fails today (broken code: ~60 writes).
Will pass after Task 4 + Task 5 strip the per-frame synthesis path.
Fixture: synthetic CellPhysics with flat floor (±10m XY, floorZ=0),
CellBSP=null so ResolveCellId keeps the indoor classification, BSP
bounding sphere centered at the global sphere center (worldPosZ +
sphereRadius = 0.43) so NodeIntersects passes in FindWalkableInternal.
worldPosZ = -0.05 places sphere bottom 0.05m below floor so
ValidateWalkable's below-surface branch fires (dist = -0.05 < -ε).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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