diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index 782c5374..aa6af66b 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -192,7 +192,6 @@ public sealed class GameWindow : IDisposable
     // yet rooted; the clipRoot flip + OutsideView terrain integration is the cutover step).
     private LoadedCell? _outdoorNode;
     private readonly List<LoadedCell> _outdoorNodeBuildingCells = new();
-    private readonly HashSet<uint> _outdoorNodeSeenLbs = new();
     private readonly HashSet<uint> _outdoorSceneParticleEntityIds = new();
     private readonly HashSet<uint> _visibleSceneParticleEntityIds = new();
     private string? _lastRenderSignature;
@@ -7464,26 +7463,38 @@ public sealed class GameWindow : IDisposable
             if (viewerRoot is null && viewerCellId != 0u)
             {
                 _outdoorNodeBuildingCells.Clear();
-                _outdoorNodeSeenLbs.Clear();
-                int onGridX = playerLb.HasValue ? (int)((playerLb.Value >> 24) & 0xFFu) : -1;
-                int onGridY = playerLb.HasValue ? (int)((playerLb.Value >> 16) & 0xFFu) : -1;
-                foreach (var onEntry in _worldState.LandblockEntries)
+                // T2 (BR-4): draw-driven flood gating. Retail floods a building's
+                // interior exactly when its shell DRAWS and an aperture survives
+                // the view (DrawBuilding Ghidra 0x0059f2a0: per-view viewconeCheck
+                // → portal-BSP walk → ConstructView's GetClip; NO distance
+                // constant anywhere on the chain). Port: a per-BUILDING frustum
+                // pre-gate on the aperture bounds (Building.PortalBounds — the
+                // tight equivalent of the shell viewconeCheck for FLOOD purposes),
+                // replacing the old Chebyshev≤1 landblock cell-sweep; the 48 m
+                // seed cap dies with it (RetailPViewRenderer seeds at ∞). The
+                // per-portal admission stays BuildFromExterior's screen clip
+                // (empty clip = no seed) — retail's GetClip-vs-view gate.
+                // Per-building iteration is also the FPS fix the 2026-06-07
+                // Chebyshev hack approximated: dozens of AABB tests instead of an
+                // O(all loaded cells) portal sweep.
+                foreach (var registry in _buildingRegistries.Values)
                 {
-                    uint onLb = (onEntry.LandblockId >> 16) & 0xFFFFu;
-                    if (playerLb.HasValue)
+                    foreach (var b in registry.All())
                     {
-                        int gX = (int)((onLb >> 8) & 0xFFu);
-                        int gY = (int)(onLb & 0xFFu);
-                        if (Math.Max(Math.Abs(gX - onGridX), Math.Abs(gY - onGridY)) > 1) continue;
+                        if (b.HasPortalBounds
+                            && !AcDream.App.Rendering.FrustumCuller.IsAabbVisible(
+                                frustum, b.PortalBounds.Min, b.PortalBounds.Max))
+                            continue;
+
+                        foreach (uint cid in b.EnvCellIds)
+                            if (_cellVisibility.TryGetCell(cid, out var bc) && bc is not null)
+                                _outdoorNodeBuildingCells.Add(bc);
                     }
-                    if (!_outdoorNodeSeenLbs.Add(onLb)) continue;
-                    foreach (var onCell in _cellVisibility.GetCellsForLandblock(onLb))
-                        _outdoorNodeBuildingCells.Add(onCell);
                 }
                 _outdoorNode = AcDream.App.Rendering.OutdoorCellNode.Build(viewerCellId);
                 if (AcDream.Core.Rendering.RenderingDiagnostics.ProbeFlapEnabled)
                     Console.WriteLine(System.FormattableString.Invariant(
-                        $"[outdoor-node] cell=0x{viewerCellId:X8} nearbyCells={_outdoorNodeBuildingCells.Count} (R-A2 per-building floods)"));
+                        $"[outdoor-node] cell=0x{viewerCellId:X8} nearbyCells={_outdoorNodeBuildingCells.Count} (T2 frustum-gated per-building floods)"));
             }
 
             uint playerCellId = _physicsEngine.DataCache?.CellGraph.CurrCell?.Id ?? 0u;
diff --git a/src/AcDream.App/Rendering/RetailPViewRenderer.cs b/src/AcDream.App/Rendering/RetailPViewRenderer.cs
index 93b045bc..e2faaf6a 100644
--- a/src/AcDream.App/Rendering/RetailPViewRenderer.cs
+++ b/src/AcDream.App/Rendering/RetailPViewRenderer.cs
@@ -26,7 +26,13 @@ public sealed class RetailPViewRenderer
 
     // R-A2: per-building flood grouping, reused across frames (inner lists cleared each frame).
     private readonly Dictionary<uint, List<LoadedCell>> _buildingGroups = new();
-    private const float OutdoorBuildingSeedDistance = 48f;
+
+    // T2 (BR-4): retail has NO distance constant on the flood-admission chain
+    // (DrawBuilding → portal walk → ConstructView: viewconeCheck + side test +
+    // GetClip + GetVisible only). The old 48 m seed cap is replaced by the
+    // caller's per-building frustum pre-gate on aperture bounds (GameWindow's
+    // gather); seeds themselves are unbounded.
+    private const float OutdoorBuildingSeedDistance = float.PositiveInfinity;
 
     public RetailPViewRenderer(
         GL gl,