T6 (BR-7) C3: per-cell shadow architecture - flood registration, building channel, per-cell query; b3ce505 stopgap DELETED (closes #99)

The A6.P4 port, fused into one installment per the BR-2 half-port lesson
(registration and query are co-dependent: flood-registering shells under
the old radial query would re-open #98 through the vestibule).

REGISTRATION (ShadowObjectRegistry rewritten):
- Register/RegisterMultiPart/UpdatePosition compute the cell set via
  CellTransit.BuildShadowCellSet (the C2 find_cell_list flood) seeded by
  the entity's m_position cell id; the private 24m XY-grid rectangle and
  its single-landblock clamp are deleted. Flood spheres follow retail's
  CylSphere rule (base point + cyl radius, cap 10; BSP bounding-sphere
  fallback - Ghidra 0x0052b9f0). Statics flood with the do_not_load
  prune; dynamics (server spawns, isStatic:false) without.
- Keep-when-empty (SetPositionInternal num_cells gate, pc:283540): a
  failed flood leaves the previous registration in place.
- RefloodLandblock: streaming-race hook re-runs the flood when a
  landblock's cells hydrate (retail init_objects -> recalc_cross_cells,
  Ghidra 0x0052b420/0x00515a30); wired at GameWindow's hydration tail.
- GameWindow sites pass the server position's full cell id as the seed
  (spawn + UpdatePosition); the five static sites pass ParentCellId.

BUILDING CHANNEL (CSortCell.building shape):
- Building SHELLS are not shadow objects in retail (only caller of
  find_building_collisions is CSortCell::find_collisions 0x005340aa;
  one building per origin landcell, init_buildings 0x0052fd80 verified
  verbatim + ACE cross-ref). IsBuildingShell entities skip the registry;
  Transition.FindBuildingCollisions runs the shell part-0 BSP off
  cache.GetBuilding(cellId) with bldg_check set around it
  (find_building_collisions 0x006b5300), CollidedWithEnvironment on
  non-Contact non-OK. BuildingPhysics.ModelId = pre-resolved part-0
  GfxObj (0x02 Setups resolved at the CacheBuilding site).
- Placement/ethereal weakening: BSPQuery Path 1 passes center_solid=0
  when BldgCheck && HitsInteriorCell (BSPTREE::find_collisions 0x0053a82e
  + placement_insert 0x005399d8) so doorway crossings don't hard-fail
  against shell solids. SpherePath gains both retail fields;
  HitsInteriorCell is rebuilt at every cell-array build
  (build_cell_array reset 0x00509ef2 + find_cell_list/check_building_
  transit set sites).

QUERY (retail per-cell order, transitional_insert 0x0050b6f0):
- TransitionalInsert per attempt: env -> building (LandCell only) ->
  objects on the PRIMARY cell, then on OK the check_other_cells pass
  (env -> building -> objects per OTHER overlapped cell) + the
  carried-cell advance - the advance now happens AFTER all per-cell
  object passes (the WF1 ordering divergence), with Adjusted/Slid
  feeding the retry exactly like retail's OK_TS case.
- FindObjCollisionsInCell = CObjCell::find_obj_collisions (0x0052b750):
  iterate ONLY the asked cell's list. DELETED: the radial 9-landblock
  sweep, the +5m query pad, the b3ce505 indoor-primary gate, and the
  isViewer exemption (the camera is bounded by interior cell-BSP env
  collision - retail's own channel; CameraCornerSealReplayTests pins it
  against real dat, and the new building-channel camera test pins the
  outdoor stop).

TESTS: Core 1416/0/2 (was 1398 + 4 pre-existing #99-era fails + 1 skip),
App 225, UI 420, Net 294 - all green.
- 3 of the 4 #99-era reds flipped green as designed: the door apparatus
  (Apparatus_Grounded_50cmOffCenter_FrontApproach_Blocks) and tick-13558
  (indoor walkthrough) now assert the door BLOCKS; tick-22760 pins the
  outdoor blocking invariant.
- The 4th (BSPStepUp D4) + 22760's lateral-slide delta are NOT cell-set
  problems (probes prove the door is found + BSP-only dispatched;
  BR-7 left both byte-identical) - filed as issue #116 (slide-response
  family), D4 skipped with the issue reference.
- FindEnvCollisionsMultiCellTests migrated to the public entry (the A4
  multi-cell halt now lives at the retail call site).
- New registry pins: per-cell query surface, outdoor-footprint-never-
  indoor (#98 architectural), door-outdoor-cell membership, reflood.
- CameraCollisionIndoorTests rewritten against the building channel
  (the isViewer-exemption pins died with the exemption).

Closes #99 (doors block both ways via registration-time cell membership
+ the straddle-spanning player cell array). #97 likely closed (the +5m
radial pad that produced phantom-collision candidates is gone) - verify
at T5. #98 stays closed ARCHITECTURALLY (outdoor footprints structurally
cannot reach interior cells; the cellar harness stays green).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/ISSUES.md

@@ -3833,6 +3833,48 @@ retail's viewer-distance smoothing (update_viewer region) before touching.
 
 ---
 
+## #116 — Slide-response divergence family: near-perpendicular lateral slide lost + first-airborne-frame in-frame slide vs hard stop
+
+**Status:** OPEN
+**Severity:** LOW-MEDIUM (over-blocking, never under-blocking — no
+walk-throughs; feel-level divergence at walls/doors)
+**Filed:** 2026-06-11 (BR-7 / A6.P4 ship session)
+**Component:** physics (slide response — `SlideSphere` degenerate-offset
+guard + first-contact-frame behavior)
+
+**Two pinned shapes, both pre-dating BR-7 (the per-cell shadow port left
+them byte-identical):**
+
+1. **Tick-22760 lateral-slide loss** (door capture, 2026-05-24): live
+   blocked the southward push at the cottage door face and KEPT the tiny
+   lateral component (X −0.0357, cn=(0,+1,0)); the harness hard-stops both
+   components (cn=(0,0,1) from the post-stop ground refresh). The movement
+   is near-perpendicular to the face, so the projected slide offset is
+   tiny and the degenerate-offset guard converts it to a full stop.
+   Repro: `DoorBugTrajectoryReplayTests.Diagnostic_Tick22760_DumpEngineInternals`
+   (door found + BSP-only dispatched correctly — `[bsp-test]` /
+   `[cyl-skip-bsp]` probes prove the cell-set layer is innocent).
+   `LiveCompare_DoorBlocksFromOutside_Tick22760` now pins the blocking
+   invariant only.
+
+2. **D4 first-airborne-frame slide** (`BSPStepUpTests.D4_*`, skipped with
+   this issue id): the L.2c pin expects the first airborne wall frame to
+   hard-stop (Z stays 2.0) with the slide starting frame 2 off the cached
+   sliding normal; since the P1-era `slide_sphere` work the engine slides
+   in-frame (Z reaches the 1.92 target on frame 1). Retail's cached-normal
+   mechanism (`CPhysicsObj::get_object_info` pc:279992, transient bit 4 →
+   `init_sliding_normal`) only governs the NEXT frame — whether retail's
+   first-frame response is hard-stop or in-frame slide needs a focused
+   oracle read (`collide_with_environment` / `slide_sphere` first-contact
+   path) before either the engine or the pin is declared wrong.
+
+**Fix shape:** one oracle-driven pass over the slide response
+(`SlideSphere` + first-contact frame), with the 22760 capture and the D4
+fixture as the acceptance pair. Do NOT patch the degenerate-offset guard
+ad hoc — the DO-NOT-RETRY table's slide entries (physics digest) apply.
+
+---
+
 # Recently closed
 
 ## #113 — Phantom staircase: REOPENED 2026-06-11, folded into the HOLISTIC BUILDING-RENDER PORT