fix(phys): A6.P3 #98 — gate outdoor shadow radial sweep on indoor primary cell

The cellar-up cap was caused by ShadowObjectRegistry.GetNearbyObjects
running its outdoor 24m-grid radial query unconditionally — including
when the moving sphere's primary cell is indoor. The landblock-baked
cottage GfxObj 0x01000A2B (registered with cellScope=0u, i.e.
landblock-wide) was returned for a sphere inside the cellar EnvCell,
and its downward-facing cottage-floor poly at world Z=94 head-bumped
the sphere from below, capping ascent at foot Z=92.74.

Diagnosis this session via the live capture in
a6-issue98-resolve-capture-2.jsonl (92K records, 132 cap events all
with body on the ramp polygon) FALSIFIED the prior "stale ramp
contact plane" hypothesis: the contact plane is correctly the ramp's
plane because the sphere IS on the ramp at the cap. The cap is a
proximate consequence of the cottage GfxObj being queried at all from
an indoor primary cell.

Retail decomp anchor (acclient_2013_pseudo_c.txt):
  - 308751-308769: CObjCell::find_cell_list branches on the moving
    object's m_position.objcell_id — INDOOR adds only that cell +
    portal-visible neighbors via CELLARRAY::add_cell; OUTDOOR adds
    all overlapping outdoor cells via CLandCell::add_all_outside_cells.
    Object-position-driven, not sphere-radius-driven.
  - 309560: CEnvCell::find_collisions calls find_env_collisions
    (own cell BSP only) THEN CObjCell::find_obj_collisions on `this`.
  - 308916: CObjCell::find_obj_collisions iterates this->shadow_object_list
    — strictly per-cell, never landblock-wide.

Combined: a landblock-baked static like the cottage building is added
to outdoor cells' shadow_object_list only (its m_position resolves to
an outdoor cell). An indoor EnvCell's shadow_object_list never
contains the cottage. CEnvCell::find_collisions therefore never tests
the sphere against the cottage. Retail-faithful behavior.

Falsification spike (this session): scoping the cottage to a single
distant outdoor cell instead of landblock-wide caused the harness
LiveCompare_FirstCap test to stop reproducing the cn=(0,0,-1) cap,
confirming the cap is caused by the radial sweep returning the
cottage to an indoor primary.

The fix:
  - Add optional `primaryCellId` parameter to
    ShadowObjectRegistry.GetNearbyObjects. When indoor (>= 0x0100),
    skip the outdoor radial sweep entirely after the indoorCellIds
    branch runs. Default 0u preserves prior behavior for
    cell-unaware callers (existing tests pass unchanged).
  - Transition.FindObjCollisions passes sp.CheckCellId.
  - Harness LiveCompare_FirstCap_* flipped to documents-the-fix form
    (asserts the downward-facing cottage-floor cap does NOT fire).
    Deletes the residual-X-motion test that documented a post-cap
    edge-slide — irrelevant once the cap is gone.

This same gate should close the other "Finding 3 family" indoor/outdoor
collision bugs (#97 phantom collisions, indoor sling-out). Visual
verification by the user is the remaining acceptance check before
closing #98.

Verification:
  - 11/11 CellarUpTrajectoryReplayTests pass in isolation
  - 55 ShadowObjectRegistry + TransitionTypes + PhysicsEngine
    + CellPhysics + CellTransit tests pass
  - 8 pre-existing static-state-leakage failures in serial physics
    suite are unchanged (verified by stash + retest on baseline)
  - dotnet build clean, 0 warnings

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/AcDream.Core/Physics/ShadowObjectRegistry.cs

@@ -254,11 +254,37 @@ public sealed class ShadowObjectRegistry
     /// grid lookup (cell ids like `0xA9B40029`) never queries the indoor key.
     /// Net effect pre-fix: interior items don't block movement.
     /// </para>
+    ///
+    /// <para>
+    /// Issue #98 (2026-05-24): the optional <paramref name="primaryCellId"/>
+    /// parameter gates the outdoor radial sweep on the SPHERE's primary cell
+    /// type. Mirrors retail's <c>CObjCell::find_cell_list</c> at
+    /// <c>acclient_2013_pseudo_c.txt:308751-308769</c>: when the sphere's
+    /// position is in an indoor cell (id ≥ 0x0100), retail only adds THAT
+    /// cell + portal-visible neighbors to the cell array — never outdoor
+    /// cells. Combined with <c>CEnvCell::find_collisions</c> only iterating
+    /// <c>this->shadow_object_list</c>, retail's indoor cells never test
+    /// against outdoor statics like landblock-baked buildings.
+    /// </para>
+    ///
+    /// <para>
+    /// Pre-fix bug shape (issue #98): the cellar EnvCell's player sphere
+    /// queried the outdoor 24-m grid via the radial sweep and picked up the
+    /// landblock-wide cottage GfxObj (registered with <c>cellScope=0</c>);
+    /// the head sphere bumped the cottage's downward-facing floor poly from
+    /// below at world Z=94 and capped the ascent. With this gate, the
+    /// outdoor sweep is skipped when the primary cell is indoor, so the
+    /// cottage is only seen from outdoor primary cells (the building's
+    /// own outdoor footprint). Default <c>primaryCellId=0</c> preserves
+    /// the pre-fix radial-only behavior for callers that don't know /
+    /// care about cell type (existing tests).
+    /// </para>
     /// </summary>
     public void GetNearbyObjects(Vector3 worldPos, float queryRadius,
                                   float worldOffsetX, float worldOffsetY, uint landblockId,
                                   List<ShadowEntry> results,
-                                  System.Collections.Generic.IReadOnlyCollection<uint>? indoorCellIds = null)
+                                  System.Collections.Generic.IReadOnlyCollection<uint>? indoorCellIds = null,
+                                  uint primaryCellId = 0u)
     {
         results.Clear();
         var seen = new HashSet<uint>();
@@ -279,6 +305,17 @@ public sealed class ShadowObjectRegistry
             }
         }
 
+        // Issue #98 (2026-05-24): when the sphere is in an INDOOR cell, skip
+        // the outdoor radial sweep entirely — retail's CEnvCell::find_collisions
+        // only iterates this->shadow_object_list, never outdoor cells'. Indoor
+        // statics are reached via indoorCellIds above. This closes the
+        // cottage-cellar Z-cap (head sphere bumping cottage floor from below
+        // because the landblock-wide cottage GfxObj was returned by the
+        // unconditional radial sweep). Callers that don't pass primaryCellId
+        // (or pass 0) keep the pre-fix radial-only behavior.
+        if ((primaryCellId & 0xFFFFu) >= 0x0100u)
+            return;
+
         // Extract landblock X/Y from the ID.
         int lbX = (int)((landblockId >> 24) & 0xFF);
         int lbY = (int)((landblockId >> 16) & 0xFF);

src/AcDream.Core/Physics/TransitionTypes.cs

@@ -2177,11 +2177,18 @@ public sealed class Transition
         _ = CellTransit.FindCellSet(engine.DataCache, currPos, sphereRadius,
                                     sp.CheckCellId, out var indoorCellIds);
 
+        // Issue #98 (2026-05-24): pass primary cellId so the radial outdoor
+        // sweep is skipped when sphere is in an indoor cell. Mirrors retail's
+        // CObjCell::find_cell_list indoor/outdoor branch
+        // (acclient_2013_pseudo_c.txt:308751-308769) — indoor cells only
+        // iterate their own shadow lists + portal-visible neighbors, never
+        // outdoor cells' shadow lists. Closes the cottage cellar-up cap.
         engine.ShadowObjects.GetNearbyObjects(
             currPos, queryRadius,
             worldOffsetX, worldOffsetY, landblockId,
             nearbyObjs,
-            indoorCellIds);
+            indoorCellIds,
+            primaryCellId: sp.CheckCellId);
 
         foreach (var obj in nearbyObjs)
         {