diff --git a/src/AcDream.App/Rendering/Wb/WbMeshAdapter.cs b/src/AcDream.App/Rendering/Wb/WbMeshAdapter.cs
index 23b2d68..0d8dee8 100644
--- a/src/AcDream.App/Rendering/Wb/WbMeshAdapter.cs
+++ b/src/AcDream.App/Rendering/Wb/WbMeshAdapter.cs
@@ -1,5 +1,7 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
 using AcDream.Core.Meshing;
 using AcDream.Core.Rendering;
 using Chorizite.OpenGLSDLBackend;
@@ -143,13 +145,39 @@ public sealed class WbMeshAdapter : IDisposable, IWbMeshAdapter
             // isSetup: false — acdream's MeshRefs already carry expanded
             // per-part GfxObj ids (0x01XXXXXX). WB's Setup-expansion path is
             // unused.
-            _ = _meshManager.PrepareMeshDataAsync(id, isSetup: false);
+            var prepTask = _meshManager.PrepareMeshDataAsync(id, isSetup: false);
 
             // [indoor-upload] requested probe — only for EnvCell ids.
             if (RenderingDiagnostics.IsEnvCellId(id) && RenderingDiagnostics.ProbeIndoorUploadEnabled)
             {
                 _pendingEnvCellRequests.Add(id);
                 Console.WriteLine($"[indoor-upload] requested cellId=0x{id:X8}");
+
+                // Phase 2 — surface what WB's catch block silently swallows.
+                // ObjectMeshManager.PrepareMeshData has a try/catch at line 589
+                // that calls _logger.LogError(ex, ...) — but we construct
+                // ObjectMeshManager with NullLogger.Instance so the log is
+                // dropped. This continuation captures the same data scoped to
+                // EnvCell ids only. Runs on ThreadPool; non-blocking. Zero cost
+                // when the probe is off.
+                ulong cellId = id;
+                _ = prepTask.ContinueWith(t =>
+                {
+                    if (t.IsFaulted && t.Exception is not null)
+                    {
+                        var ex = t.Exception.InnerException ?? t.Exception;
+                        var stack = (ex.StackTrace ?? "").Split('\n')
+                            .Take(3).Select(s => s.Trim()).Where(s => s.Length > 0);
+                        Console.WriteLine(
+                            $"[indoor-upload] FAILED cellId=0x{cellId:X8} " +
+                            $"exception={ex.GetType().Name}: {ex.Message} " +
+                            $"stack=[{string.Join(" | ", stack)}]");
+                    }
+                    else if (t.IsCompletedSuccessfully && t.Result is null)
+                    {
+                        Console.WriteLine($"[indoor-upload] NULL_RESULT cellId=0x{cellId:X8}");
+                    }
+                }, TaskScheduler.Default);
             }
         }
     }