fix(render): feed look-in cells to particle and light visibility

Look-in rooms (cells reached through building portals) drew their
geometry but never entered the visible-cell set consumed by the
particle gate and the point-light candidacy scope, so their emitters
stayed frozen and their lanterns dark until the player entered or the
camera left the building. Retail has no look-in split:
ShouldDrawParticles @0x0050FE60 gates on cell->IsInView(), and a cell
installed by DrawBuilding @0x0059F2A0 -> PView::ConstructView
@0x005A57B0 is drawn by the same DrawCells traversal as any flooded
cell, so it is in view identically (per-cell in_view stamped by
PView::InitCell @0x005A4B70).

RetailPViewFrameResult now carries InViewCells (main flood + look-in
cells, the existing prepareCells union; the borrowed-scratch contract
is unchanged because RecycleLookInFrames runs at the start of the next
DrawInside). WorldSceneRenderer feeds InViewCells to
ParticleVisibilityController and the point-light scope. DrawableCells
is untouched for seals, the outside-stage predicate, diagnostics, and
the packed-product referee. The legacy 4-arg Reset defaults
InViewCells = DrawableCells for standalone callers.

User-gated 2026-08-29 at the Sanctuary Cathedral: adjacent look-in
rooms show particles and lantern lights from the root cell without
entry or an outside camera; recall/waterfall/Holtburg/paperdoll
unregressed. The pre-existing #132-family candle-behind-opening
report remains open and is unchanged by this fix.

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

src/AcDream.App/Rendering/RetailPViewRenderer.cs

@@ -251,10 +251,13 @@ public sealed class RetailPViewRenderer
             RenderProjectionCounts sourceCounts = frameViewBorrowed
                 ? frameView.SourceDigest.Counts
                 : LegacySourceCounts(partition!);
+            // prepareCells is exactly "main flood ∪ look-in cells" — the cells
+            // this traversal actually reached, i.e. retail's in-view set.
             RetailPViewFrameResult result = _frameResultScratch.Reset(
                 pvFrame,
                 clipAssembly,
                 drawableCells,
+                prepareCells,
                 counts,
                 sourceCounts,
                 partition);
@@ -1910,6 +1913,23 @@ public sealed class RetailPViewFrameResult
     public PortalVisibilityFrame PortalFrame { get; private set; } = null!;
     public ClipFrameAssembly ClipAssembly { get; private set; } = null!;
     public HashSet<uint> DrawableCells { get; private set; } = null!;
+
+    /// <summary>
+    /// Every cell this completed view actually reached: the main flood
+    /// (<see cref="DrawableCells"/>) plus the building look-in cells. This is
+    /// retail's per-cell <c>in_view</c> answer for effect consumers —
+    /// <c>CPhysicsObj::ShouldDrawParticles</c> @0x0050FE60 gates on
+    /// <c>cell-&gt;IsInView()</c>, and a cell entered through a building portal
+    /// (<c>PView::ConstructView</c> @0x005A57B0, installed by
+    /// <c>RenderDeviceD3D::DrawBuilding</c> @0x0059F2A0) is drawn by the same
+    /// <c>PView::DrawCells</c> traversal as a flooded cell, so retail marks it
+    /// in view identically. acdream's look-in adaptation keeps those cells out
+    /// of <see cref="DrawableCells"/> (seals / outside-stage predicate stay
+    /// main-flood scoped, #124); particle and light visibility must consume
+    /// THIS set or look-in rooms render with frozen emitters and dark lights.
+    /// </summary>
+    public HashSet<uint> InViewCells { get; private set; } = null!;
+
     internal RenderFrameDiagnosticCounts DiagnosticCounts { get; private set; }
     internal RenderProjectionCounts SourceCounts { get; private set; }
     internal InteriorEntityPartition.Result? DiagnosticPartition
@@ -1919,6 +1939,7 @@ public sealed class RetailPViewFrameResult
         PortalVisibilityFrame portalFrame,
         ClipFrameAssembly clipAssembly,
         HashSet<uint> drawableCells,
+        HashSet<uint> inViewCells,
         RenderFrameDiagnosticCounts diagnosticCounts,
         RenderProjectionCounts sourceCounts,
         InteriorEntityPartition.Result? diagnosticPartition)
@@ -1926,6 +1947,7 @@ public sealed class RetailPViewFrameResult
         PortalFrame = portalFrame;
         ClipAssembly = clipAssembly;
         DrawableCells = drawableCells;
+        InViewCells = inViewCells;
         DiagnosticCounts = diagnosticCounts;
         SourceCounts = sourceCounts;
         DiagnosticPartition = diagnosticPartition;
@@ -1941,6 +1963,7 @@ public sealed class RetailPViewFrameResult
             portalFrame,
             clipAssembly,
             drawableCells,
+            drawableCells,
             RetailPViewRenderer.LegacyDiagnosticCounts(
                 diagnosticPartition),
             RetailPViewRenderer.LegacySourceCounts(

src/AcDream.App/Rendering/WorldSceneRenderer.cs

@@ -254,8 +254,14 @@ internal sealed class WorldSceneRenderer : IPreparedWorldSceneFramePhase
                         camera.Camera.View,
                         _diagnostics.CameraCellResolution));
 
-                _particleVisibility.MarkVisibleCells(pviewResult.DrawableCells);
-                _frames.ObserveDrawableCells(pviewResult.DrawableCells);
+                // Effect visibility consumes InViewCells (main flood ∪ look-in
+                // cells), not the flood-only DrawableCells: retail's
+                // ShouldDrawParticles @0x0050FE60 asks cell->IsInView(), and a
+                // look-in cell drawn via DrawBuilding @0x0059F2A0 is in view
+                // exactly like a flooded cell. Flood-only scoping froze
+                // emitters and darkened lights in visible adjacent rooms.
+                _particleVisibility.MarkVisibleCells(pviewResult.InViewCells);
+                _frames.ObserveDrawableCells(pviewResult.InViewCells);
                 _diagnostics.EmitPViewInput(
                     pviewResult.PortalFrame,
                     camera.ViewProjection,

src/AcDream.Core/Lighting/LightManager.cs

@@ -271,8 +271,10 @@ public sealed class LightManager
     /// geometrically closer than the player's own room's torches and win the cap,
     /// leaving the visible room dark. Scoping candidacy to the frame's actual
     /// visible cells (the render already computes this — callers pass last frame's
-    /// <c>RetailPViewFrameResult.DrawableCells</c>, one frame of latency, to avoid
-    /// re-threading a mid-render callback) removes those from contention before the
+    /// <c>RetailPViewFrameResult.InViewCells</c>, the main flood PLUS building
+    /// look-in cells, one frame of latency, to avoid re-threading a mid-render
+    /// callback; flood-only scoping darkened look-in rooms' lanterns) removes
+    /// non-visible cells from contention before the
     /// cap ever applies. The distance-sort anchor stays the PLAYER either way — this
     /// parameter only narrows candidacy, it does not change the sort (the #176
     /// correction: CAMERA anchoring, not cell scoping itself, caused the earlier