From 914638819d419307167ab19683ce59bb6785eaa5 Mon Sep 17 00:00:00 2001
From: Erik <erik.nihlen@gmail.com>
Date: Tue, 19 May 2026 12:36:37 +0200
Subject: [PATCH] feat(wb): extend NULL_RESULT probe with reader-divergence
 diagnostic
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Phase 2 Task 1's continuation logged [indoor-upload] NULL_RESULT
when WB's PrepareMeshDataAsync returned null. Extend the line to
include two cross-checks:

  ourCellDb.TryGet=<bool>    — acdream's DatCollection.Cell.TryGet<EnvCell>
  wbResolveId.Count=<int>    — WB's DefaultDatReaderWriter.ResolveId().Count

This narrows the cause among WB's null-return paths (ResolveId empty
vs TryGet<EnvCell> failure vs wrong type). Best-effort: both calls
wrapped in try/catch so diagnostic failures don't propagate.

Capture: 55 NULL_RESULTs across multiple landblocks ALL show
ourCellDb.TryGet=True + wbResolveId.Count=1. Both readers find the
cells in their indices, but WB's downstream PrepareMeshData logic
still returns null. Divergence is downstream of ResolveId.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 src/AcDream.App/Rendering/Wb/WbMeshAdapter.cs | 25 ++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/AcDream.App/Rendering/Wb/WbMeshAdapter.cs b/src/AcDream.App/Rendering/Wb/WbMeshAdapter.cs
index 0d8dee8..9893e31 100644
--- a/src/AcDream.App/Rendering/Wb/WbMeshAdapter.cs
+++ b/src/AcDream.App/Rendering/Wb/WbMeshAdapter.cs
@@ -175,7 +175,30 @@ public sealed class WbMeshAdapter : IDisposable, IWbMeshAdapter
                     }
                     else if (t.IsCompletedSuccessfully && t.Result is null)
                     {
-                        Console.WriteLine($"[indoor-upload] NULL_RESULT cellId=0x{cellId:X8}");
+                        // Phase 2 cause-narrowing: WB's PrepareMeshData can return
+                        // null for several reasons (ResolveId empty / TryGet<EnvCell>
+                        // failed / type Unknown). Cross-check against acdream's own
+                        // DatCollection — if WE find the cell but WB doesn't, the
+                        // divergence is between dat readers, not a missing record.
+                        bool ourCellFound = false;
+                        try
+                        {
+                            ourCellFound = _dats?.Cell.TryGet<DatReaderWriter.DBObjs.EnvCell>(
+                                (uint)cellId, out _) ?? false;
+                        }
+                        catch { /* swallow — this is best-effort diagnostic */ }
+
+                        int wbResolveCount = -1;
+                        try
+                        {
+                            wbResolveCount = _wbDats?.ResolveId((uint)cellId).Count() ?? -1;
+                        }
+                        catch { /* swallow — best-effort */ }
+
+                        Console.WriteLine(
+                            $"[indoor-upload] NULL_RESULT cellId=0x{cellId:X8} " +
+                            $"ourCellDb.TryGet={ourCellFound} " +
+                            $"wbResolveId.Count={wbResolveCount}");
                     }
                 }, TaskScheduler.Default);
             }