fix(selection): port SmartBox click lighting pulse

Port the retail high/low material-lighting cadence for successful world clicks, keep it instance-scoped in the modern renderer, and restore authored lighting after 0.8 seconds. Correct the selection oracle and pin timing plus per-frame buffer lifecycle with tests.

Co-authored-by: Codex <codex@openai.com>

tests/AcDream.App.Tests/Rendering/RetailSelectionLightingPulseTests.cs

@@ -0,0 +1,75 @@
+using AcDream.App.Rendering.Selection;
+
+namespace AcDream.App.Tests.Rendering;
+
+public sealed class RetailSelectionLightingPulseTests
+{
+    [Fact]
+    public void ClickRunsRetailHighLowHighLowRestoreCadence()
+    {
+        double now = 10d;
+        var pulse = new RetailSelectionLightingPulse(() => now);
+
+        pulse.Start(0x5000_1234u);
+        AssertLighting(pulse, 0x5000_1234u, RetailSelectionLighting.High);
+
+        now = 10.199;
+        pulse.Tick();
+        AssertLighting(pulse, 0x5000_1234u, RetailSelectionLighting.High);
+
+        now = 10.2;
+        pulse.Tick();
+        AssertLighting(pulse, 0x5000_1234u, RetailSelectionLighting.Low);
+
+        now = 10.4;
+        pulse.Tick();
+        AssertLighting(pulse, 0x5000_1234u, RetailSelectionLighting.High);
+
+        now = 10.6;
+        pulse.Tick();
+        AssertLighting(pulse, 0x5000_1234u, RetailSelectionLighting.Low);
+
+        now = 10.8;
+        pulse.Tick();
+        Assert.False(pulse.TryGet(0x5000_1234u, out _));
+    }
+
+    [Fact]
+    public void LongFrameAdvancesOnlyOneRetailGlobalLoopFlip()
+    {
+        double now = 1d;
+        var pulse = new RetailSelectionLightingPulse(() => now);
+        pulse.Start(0x5000_1234u);
+
+        now = 20d;
+        pulse.Tick();
+
+        AssertLighting(pulse, 0x5000_1234u, RetailSelectionLighting.Low);
+    }
+
+    [Fact]
+    public void NewClickRestoresOldTargetAndRestartsHighOnNewTarget()
+    {
+        double now = 4d;
+        var pulse = new RetailSelectionLightingPulse(() => now);
+        pulse.Start(0x5000_0001u);
+
+        now = 4.2;
+        pulse.Tick();
+        AssertLighting(pulse, 0x5000_0001u, RetailSelectionLighting.Low);
+
+        pulse.Start(0x5000_0002u);
+
+        Assert.False(pulse.TryGet(0x5000_0001u, out _));
+        AssertLighting(pulse, 0x5000_0002u, RetailSelectionLighting.High);
+    }
+
+    private static void AssertLighting(
+        RetailSelectionLightingPulse pulse,
+        uint serverGuid,
+        RetailSelectionLighting expected)
+    {
+        Assert.True(pulse.TryGet(serverGuid, out var actual));
+        Assert.Equal(expected, actual);
+    }
+}

tests/AcDream.App.Tests/Rendering/Wb/InstanceGroupClearTests.cs

@@ -7,8 +7,8 @@ namespace AcDream.App.Tests.Rendering.Wb;
 public class InstanceGroupClearTests
 {
     // #193 (regression from #188, 2026-07-09): WbDrawDispatcher's InstanceGroup holds
-    // five per-instance parallel lists — Matrices, Slots, LightSets, IndoorFlags,
-    // Opacities — appended in lockstep (one entry per drawn instance) every frame. The
+    // six per-instance parallel lists — Matrices, Slots, LightSets, IndoorFlags,
+    // Opacities, SelectionLighting — appended in lockstep (one entry per drawn instance) every frame. The
     // per-frame reset must clear ALL of them. #188 added Opacities but left it out of
     // the inline clear loop, so it grew one float per instance per frame forever; as
     // List<float>'s backing array doubled it produced ~128 MB / ~512 MB LOH float[]
@@ -23,6 +23,7 @@ public class InstanceGroupClearTests
         grp.LightSets.Add(-1);
         grp.IndoorFlags.Add(0u);
         grp.Opacities.Add(1.0f);
+        grp.SelectionLighting.Add(new Vector2(0f, 1f));
 
         grp.ClearPerInstanceData();
 
@@ -31,5 +32,6 @@ public class InstanceGroupClearTests
         Assert.Empty(grp.LightSets);
         Assert.Empty(grp.IndoorFlags);
         Assert.Empty(grp.Opacities); // #193 — the list that leaked
+        Assert.Empty(grp.SelectionLighting);
     }
 }