diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index a60ed6a8..2365ca14 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -5097,6 +5097,7 @@ public sealed class GameWindow : IDisposable
     // #131 [outstage-pt] probe state (throwaway — strip when #131 closes).
     private string? _lastOutStagePtSig;
     private readonly HashSet<uint> _outStageUnmatchedScratch = new();
+    private readonly HashSet<uint> _outStageMatchedScratch = new();
 
     private static System.Numerics.Vector3 SkyPesAnchor(
         AcDream.Core.World.SkyObjectData obj,
@@ -9742,19 +9743,28 @@ public sealed class GameWindow : IDisposable
         {
             int matched = 0, attached = 0, unattached = 0;
             _outStageUnmatchedScratch.Clear();
+            _outStageMatchedScratch.Clear();
             foreach (var (emitter, _) in _particleSystem.EnumerateLive())
             {
                 if (emitter.AttachedObjectId == 0) { unattached++; continue; }
                 attached++;
-                if (_outdoorSceneParticleEntityIds.Contains(emitter.AttachedObjectId)) matched++;
+                if (_outdoorSceneParticleEntityIds.Contains(emitter.AttachedObjectId))
+                {
+                    matched++;
+                    if (_outStageMatchedScratch.Count < 48)
+                        _outStageMatchedScratch.Add(emitter.AttachedObjectId);
+                }
                 else if (_outStageUnmatchedScratch.Count < 12)
                     _outStageUnmatchedScratch.Add(emitter.AttachedObjectId);
             }
             var unm = new System.Text.StringBuilder(96);
             foreach (uint id in _outStageUnmatchedScratch)
                 unm.Append(System.FormattableString.Invariant($" 0x{id:X8}"));
+            var mat = new System.Text.StringBuilder(192);
+            foreach (uint id in _outStageMatchedScratch)
+                mat.Append(System.FormattableString.Invariant($" 0x{id:X8}"));
             string ptSig = System.FormattableString.Invariant(
-                $"ids={_outdoorSceneParticleEntityIds.Count} attachedEmitters={attached} matched={matched} unattached={unattached} unmatchedIds=[{unm}]");
+                $"ids={_outdoorSceneParticleEntityIds.Count} attachedEmitters={attached} matched={matched} unattached={unattached} matchedIds=[{mat}] unmatchedIds=[{unm}]");
             if (ptSig != _lastOutStagePtSig)
             {
                 _lastOutStagePtSig = ptSig;
diff --git a/tests/AcDream.App.Tests/Rendering/Issue131SetupProbeTests.cs b/tests/AcDream.App.Tests/Rendering/Issue131SetupProbeTests.cs
new file mode 100644
index 00000000..49cca50f
--- /dev/null
+++ b/tests/AcDream.App.Tests/Rendering/Issue131SetupProbeTests.cs
@@ -0,0 +1,69 @@
+using System;
+using DatReaderWriter;
+using DatReaderWriter.Options;
+using Xunit;
+using Xunit.Abstractions;
+using DatSetup = DatReaderWriter.DBObjs.Setup;
+using DatGfxObj = DatReaderWriter.DBObjs.GfxObj;
+
+namespace AcDream.App.Tests.Rendering;
+
+/// <summary>
+/// #131 diagnostic (throwaway): identify the Holtburg portal among the
+/// outside-stage setup ids captured by the [outstage] probe, by dumping each
+/// candidate setup's parts + bounds from the dat. The portal's setup is the
+/// translucent swirl; lamp posts / creatures / signs identify by part shape.
+/// </summary>
+public class Issue131SetupProbeTests
+{
+    private readonly ITestOutputHelper _out;
+    public Issue131SetupProbeTests(ITestOutputHelper output) => _out = output;
+
+    [Fact]
+    public void Diagnostic_DumpOutstageCandidateSetups()
+    {
+        var datDir = CornerFloodReplayTests.ResolveDatDir();
+        if (datDir is null) { _out.WriteLine("SKIP: dats unavailable"); return; }
+        using var dats = new DatCollection(datDir, DatAccessType.Read);
+
+        uint[] candidates =
+        {
+            0x020010AC, // 0x7A9B4050 PASS r=11.9 — portal candidate A
+            0x02000B8E, // 0x7A9B403B PASS r=11.6 — portal candidate B
+            0x020019FF, // many instances (lamp posts?)
+            0x02000290,
+            0x02000001, // baseline (human?)
+            0x02000E08,
+        };
+
+        foreach (uint setupId in candidates)
+        {
+            var setup = dats.Get<DatSetup>(setupId);
+            if (setup is null)
+            {
+                _out.WriteLine(FormattableString.Invariant($"setup 0x{setupId:X8}: NOT FOUND"));
+                continue;
+            }
+            _out.WriteLine(FormattableString.Invariant(
+                $"setup 0x{setupId:X8}: parts={setup.Parts.Count}"));
+            int shown = 0;
+            foreach (uint partId in setup.Parts)
+            {
+                if (shown++ >= 4) { _out.WriteLine("    ..."); break; }
+                var gfx = dats.Get<DatGfxObj>(partId);
+                if (gfx is null) { _out.WriteLine(FormattableString.Invariant($"    part 0x{partId:X8}: not found")); continue; }
+                var sb = new System.Text.StringBuilder();
+                sb.Append(FormattableString.Invariant(
+                    $"    part 0x{partId:X8}: polys={gfx.Polygons.Count} verts={gfx.VertexArray.Vertices.Count} surfaces=["));
+                int sShown = 0;
+                foreach (uint surfId in gfx.Surfaces)
+                {
+                    if (sShown++ >= 6) { sb.Append(" ..."); break; }
+                    sb.Append(FormattableString.Invariant($" 0x{surfId:X8}"));
+                }
+                sb.Append(" ]");
+                _out.WriteLine(sb.ToString());
+            }
+        }
+    }
+}