Code review caught a CRITICAL under-inclusion: ApplyReciprocalClip scanned for the
first OtherCellId match, so a cell with two portals to the same neighbour clipped both
near-side openings against the FIRST reciprocal polygon — hiding geometry through the
second opening (real on Holtburg cellar cells 0x148<->0x149). Plumb the dat's
OtherPortalId back-link through CellPortalInfo + BuildLoadedCell and index the reciprocal
directly (retail arg2->other_portal_id, 433557). Skip (degrade to over-include) when the
index is unresolvable — never clip against a guessed polygon. Adds a disjoint two-back-
portal regression test.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
BuildLoadedCell now reads the full portal polygon vertices from
cellStruct.Polygons[portal.PolygonId].VertexIds and stores them in
local-space on the LoadedCell. Empty arrays for unresolved polygons.
Same source as the ClipPlane block; no new dat read.
Unit test covers the data-class invariant (parallel indexing) since
the full integration is exercised only at runtime with live dat data.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
