Cutover-flip follow-up: see-through buildings from outside. When the outdoor-node flood reaches a building, each interior cell is meant to draw clipped to its doorway aperture. But DrawEnvCellShells falls back to the no-clip slot 0 (full-screen) when a cell's aperture degenerates — screen-covering when you get close, or edge-on. Indoors that fallback is load-bearing (it seals the room the camera stands in; near walls hide the over-draw). From OUTSIDE it paints the building interior across the whole screen, depth-tested, so it shows wherever the solid exterior does not cover — the see-through walls, appearing 'past a threshold' exactly where the aperture degenerates.
Fix: for the outdoor-node root only, skip a flooded interior cell with no real plane-clip slot (HasRealClipSlot). From outside, 'no real aperture' means 'do not paint this interior', not 'paint it everywhere'. Interior roots keep the seal-everything slot-0 fallback unchanged. Applied to DrawEnvCellShells AND DrawCellObjectLists so a skipped cell shows neither walls nor furniture; the dead DrawPortal exterior look-in gets the same gate.
Root cause traced over the WB EnvCell render path: CellMesh.cs is physics-only; ObjectMeshManager.PrepareCellStructMeshData builds double-sided walls, so this was never a culling bug. App 216/0, build green. Visual gate pending.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>