#118: outdoor dynamics draw in the outside stage under interior roots - the house-exit clip+vanish was the SEAL z-killing the player

Root cause (pinned by the new deterministic exit-walk harness, NOT guessed):
under an interior render root, the exit-portal SEAL stamps the door fan at
TRUE depth after the gated full depth clear, and T1's "ALL dynamics last"
pass then drew the outdoor-classified player depth-tested - every fragment
beyond the door plane z-failed against the seal across the whole aperture.
Harness measured the full window: from the moment the sphere center crosses
the plane until the eye follows (~2.6 m of camera lag, ~2.2 s at walk speed)
the player is invisible; while straddling, the beyond-plane body half clips
at the plane. The handoff's three cone-level candidates are all EXONERATED:
the cone walk passes every step; (eye, ViewerCellId) come from the same
SweepEye call with camera-update-before-visibility-read in the same frame;
the side-test window is sub-epsilon under healthy resolution.

Retail oracle (grep-named-first): PView::DrawCells 0x005a4840 runs
LScape::draw FIRST (pc:432719), then the gated depth clear (pc:432731-32)
and the exit-portal seals (pc:432785-86); outdoor cell objects draw inside
the landscape stage (DrawBlock 0x005a17c0 -> DrawSortCell pc:430124), and
an object draws once per overlapped shadow cell (pc:430056-64) - the
straddling body composes from both stages, neither half clips.

Fix: RetailPViewRenderer assigns dynamics to the OUTSIDE stage under an
interior root when outdoor-classified OR sphere-straddling an exit-portal
plane of their flood-visible cell (DynamicDrawsInOutsideStage - pure, the
harness drives it as the ordering contract); they ride the landscape slice
draw (pre-clear, seal-protected) with the same per-slice cone test as
outdoor statics. Indoor dynamics keep the last pass (retail loop C);
straddlers draw in both (retail shadow dual-draw). Outdoor roots keep
all-dynamics-last - the BR-2 punch-after-dynamics lesson (88be519) stands.

Apparatus: HouseExitWalkReplayTests - dat-backed corner-building exit walk
driving the production stack headlessly (RetailChaseCamera damping ->
healthy-sweep viewer resolution -> PortalVisibilityBuilder.Build ->
ClipFrameAssembler -> ViewconeCuller -> the DrawDynamicsLast predicate +
a CPU seal-depth model). 5 tests: cone pin, seal-depth pin, straddle
dual-draw pin, per-step table, stale-root window quantifier (#118 cand 2).

Suites: App 232 (227+5), Core 1416+2skip, UI 420, Net 294.

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

src/AcDream.App/Rendering/InteriorEntityPartition.cs

@@ -73,9 +73,14 @@ public static class InteriorEntityPartition
         return result;
     }
 
-    private static bool IsIndoorCellId(uint cellId)
+    /// <summary>Shared indoor classification — keep DrawDynamicsLast, the
+    /// outside-stage assignment (#118), and the partition in lockstep.</summary>
+    public static bool IsIndoorCellId(uint cellId)
     {
         uint low = cellId & 0xFFFFu;
         return low >= 0x0100u && low != 0xFFFFu;
     }
+
+    /// <inheritdoc cref="IsIndoorCellId(uint)"/>
+    public static bool IsIndoorCellId(uint? cellId) => cellId is uint c && IsIndoorCellId(c);
 }