Single-call-site defect in TransitionTypes.cs:1442 — the indoor cell
BSP query invokes BSPQuery.FindCollisions without passing the cell's
world rotation or world origin. Path 3 step-down + Path 4 land write
ContactPlanes with D ≈ 0 instead of the cell's world floor Z.
320 corrupt CP writes per Holtburg session per the [cp-write] probe
capture 2026-05-20.
Fix: decompose cellPhysics.WorldTransform once, pass rotation +
translation. Mirrors the existing correct pattern at :1808 (object
BSP via FindObjCollisions).
This is slice 1 of 2 for the indoor ContactPlane retention phase.
Slice 2 (Bug A — TryFindIndoorWalkablePlane removal) deferred
pending Bug B retest.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
