THE doorway flap root cause, found via [flap-cam]/[shell]/[cell-transit] (2026-06-03):
the player spawned + stood still in the room (cell 0171, NO [cell-transit] after teleport),
yet the render rooted at the vestibule (0170) for all 77,951 frames — drawing only 0170's
~8-triangle shell, the rest = GL clear color = the bluish void.
CellGraph.CurrCell IS "the player's cell" (the render root), but it was written by
SetCurrAndReturn inside the PER-ENTITY ResolveWithTransition + ResolveCellId — so EVERY NPC
wrote it. A Holtburg NPC (0x000F4240) jump-looping near the doorway clobbered the player's
render root every tick. Standing still (player makes no resolve calls) the NPC's write wins
→ stuck blue void; moving, player/NPC writes fight → the flap. This is why the membership
pick fix (correct, kept) didn't change the visual — the render root was clobbered regardless.
Fix: CurrCell is now written ONLY by the player. New PhysicsEngine.UpdatePlayerCurrCell is
called from PlayerMovementController.UpdateCellId — the single player-only chokepoint for
CellId (teleport / server snap @ SetPosition + per-frame resolver). Removed the CurrCell
write from SetCurrAndReturn (inlined the 2 resolve call sites to sp.CurCellId) and the 4
ResolveCellId sites. NPCs no longer touch the render root. Teleport→UpdateCellId also covers
spawn/standing-still (CurrCell = the player's spawn cell immediately).
CellGraphMembershipTests rewritten to the new contract (3 tests): UpdatePlayerCurrCell writes
the render root; ResolveCellId does NOT (the blue-hole guard); stale-beats-null preserved.
Full Core suite: 1295 pass / 5 fail = the documented §10 baseline, zero new breakage.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Port retail CObjCell::find_cell_list do_not_load_cells prune
(acclient_2013_pseudo_c.txt:308829-308867) as indoor->outdoor doorway
hysteresis: hold the previous indoor cell when the outdoor candidate is
not in its stab list AND the foot-sphere still overlaps the cell's
containment BSP expanded by DoorwayHoldMargin. Kills the front-door
0170<->0031 ping-pong (handoff §5) the #98 saga never addressed. Fires
only at the front-door seam; the cellar has no exit portal so it never
falls through here (#98 cellar-up untouched).
Three TDD tests in CellGraphMembershipTests: HOLD (the RED->GREEN case,
Y=3.9 inside the 0.2 m margin), RELEASE when fully outside (Y=4.5
exceeds expanded margin), and stab-list gate (outdoor candidate in stab
list releases even near the boundary).
Adds using System.Linq for IReadOnlyList.Contains at the prune site.
SphereOverlapsEnvCell helper mirrors BSPQuery.SphereIntersectsCellBsp
via EnvCell.InverseWorldTransform + ContainmentBsp.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Add private `SetCurrAndReturn(uint)` helper in PhysicsEngine that looks up
the resolved id in `DataCache.CellGraph` and writes `CurrCell` when the cell
is present. Wrap the four RESOLVED-id return sites in ResolveCellId:
- indoor no-CellBSP return (trust FindCellList)
- indoor sphere-overlaps-CellBSP return
- outdoor→indoor building-transit return (foreach candidate)
- outdoor terrain-grid return
The final no-match `return fallbackCellId;` is intentionally NOT wrapped —
stale beats null (the caller's seed is preserved unchanged).
CurrCell has zero readers in src/ (verified by ripgrep); this is additive
write-only, identical observable behavior to W1. One new unit test
(CellGraphMembershipTests) proves RED→GREEN.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
