The two Core physics primitives retail's SmartBox::update_viewer calls down into,
ported verbatim (TDD, 7 new tests):
- CellTransit.FindVisibleChildCell (CEnvCell::find_visible_child_cell, pc:311397):
return the cell whose cell-BSP point_in_cell contains a world point — start cell
first, then (stab-list mode) the start's VisibleCellIds or (portal mode) its
direct portals. Sibling of FindCellList. Mirrors FindCellList's null-CellBSP skip
(CellTransit.cs:518) so a cell lacking hydrated CellBSP doesn't spuriously claim
every point via PointInsideCellBsp's null-node "inside" default.
- PhysicsEngine.AdjustPosition (CPhysicsObj::AdjustPosition, pc:280009): resolve a
point's cell from a seed. Indoor (>=0x100) → FindVisibleChildCell(stab-list);
outdoor → landcell snap (same grid lookup as ResolveCellId). The seen_outside
sub-fallback is deferred (off the cottage/cellar path; spec §6).
Both are unwired into any production path — they land the machinery update_viewer's
start-cell + fallback 1 need (and that residual C also needs). The App SweepEye
orchestration that calls them lands next.
Decomp-faithful per the live-capture finding: A's V1 sweep already contains the eye
(eyeInRoot=Y 99.75%, never void); this completes A as a verbatim port. Spec:
docs/superpowers/specs/2026-06-05-residual-a-camera-collision-design.md.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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