diff --git a/docs/ISSUES.md b/docs/ISSUES.md
index aa939074..120229f6 100644
--- a/docs/ISSUES.md
+++ b/docs/ISSUES.md
@@ -4021,12 +4021,30 @@ in the render digest) and shows a water barrel that retail doesn't.
**Lead (from the T5 launch log):** exactly two
`[up-null] upload returned null for 0x00010002B4 / 0x00010008A8 — caching
-EMPTY render data (permanently invisible)` lines at startup. Identify
-which models those are (likely GfxObjs 0x010002B4 / 0x010008A8 — plausibly
-the stair parts) and why `ObjectMeshManager`'s upload returned null; the
-"permanently invisible" cache makes any transient failure sticky. The
-barrel is a separate static-inclusion question (which cell owns it, and
-is it admitted by a view it shouldn't be).
+EMPTY render data (permanently invisible)` lines at startup.
+
+**Narrowed 2026-06-11 (the [up-null] lead is EXONERATED, dat-proven):**
+`Issue119UpNullGfxObjDumpTests` — both GfxObjs are legitimately no-draw
+models: 0x010002B4 = 9 polys, ALL `NoPos`, all surfaces `Base1Solid`;
+0x010008A8 = 1 poly, `NoPos`, `Base1Solid|Translucent`. Retail's
+skipNoTexture never draws them either (the BR-1 equivalence) — the empty
+cache is the CORRECT terminal state, and the alarming log line was the
+only defect (reworded; it stays as a tripwire for the real-failure shape).
+Second fact, same test: on the hall/tower shell 0x010014C3, ZERO textured
+polys are dropped by the extraction gates (137/149 draw; the 12 dropped
+are the known #113 no-draw orphans) — the per-poly extraction is
+exonerated for building shells, pinned by
+`ShellModel_NoTexturedPolyIsDropped`.
+
+**Remaining hypothesis space (needs the re-gate to identify the exact
+tower):** the missing stair parts draw from somewhere other than the
+shell GfxObj's per-poly extraction — most plausibly interior stair-CELL
+shells whose visibility depends on the flood admitting those cells from
+the outside view, or a different building model than assumed. At the
+re-gate: have the user point at the tower (one sentence / approx
+location) — then the cell set + flood can be replayed headlessly like
+#118. The extraneous water barrel remains a separate static-inclusion
+question (which cell owns it; is it admitted by a view it shouldn't be).
---
diff --git a/src/AcDream.App/Rendering/Wb/ObjectMeshManager.cs b/src/AcDream.App/Rendering/Wb/ObjectMeshManager.cs
index 7817fa75..d717a934 100644
--- a/src/AcDream.App/Rendering/Wb/ObjectMeshManager.cs
+++ b/src/AcDream.App/Rendering/Wb/ObjectMeshManager.cs
@@ -715,9 +715,16 @@ namespace AcDream.App.Rendering.Wb {
var renderData = UploadGfxObjMeshData(meshData);
if (renderData == null) {
- // TEMP diagnostic #105 (strip with fix): the empty substitute is cached in
- // _renderData forever -> the object exists but never draws (invisible walls).
- Console.WriteLine($"[up-null] upload returned null for 0x{meshData.ObjectId:X10} — caching EMPTY render data (permanently invisible)");
+ // 0-vertex mesh: every polygon was gated out at extraction. #119
+ // (2026-06-11) dat-verified this is LEGITIMATE for all-no-draw
+ // models (all polys NoPos + Base1Solid surfaces — retail's
+ // skipNoTexture never draws them either; 0x010002B4/0x010008A8
+ // are this class, Issue119UpNullGfxObjDumpTests). The empty
+ // cache is the correct terminal state for those. The line stays
+ // as a tripwire for the OTHER way to get here (extraction
+ // dropped textured polys — a real defect; dat-verify with the
+ // dump test before treating as one).
+ Console.WriteLine($"[up-null] 0x{meshData.ObjectId:X10} produced a 0-vertex mesh — caching empty render data (legitimate for all-no-draw models; dat-verify via Issue119UpNullGfxObjDumpTests)");
renderData = new ObjectRenderData();
}
diff --git a/tests/AcDream.Core.Tests/Conformance/Issue119UpNullGfxObjDumpTests.cs b/tests/AcDream.Core.Tests/Conformance/Issue119UpNullGfxObjDumpTests.cs
new file mode 100644
index 00000000..be5e4413
--- /dev/null
+++ b/tests/AcDream.Core.Tests/Conformance/Issue119UpNullGfxObjDumpTests.cs
@@ -0,0 +1,139 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using DatReaderWriter;
+using DatReaderWriter.DBObjs;
+using DatReaderWriter.Enums;
+using DatReaderWriter.Options;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace AcDream.Core.Tests.Conformance;
+
+///
+/// #119 diagnostic dump (2026-06-11): GfxObjs 0x010002B4 and 0x010008A8 hit
+/// `[up-null] upload returned null — caching EMPTY render data (permanently
+/// invisible)` at startup (t5-gate-launch.log:33-34); the old tower shows
+/// missing stair parts (visible in retail — user axiom). UploadGfxObjMeshData
+/// returns null only when the PREPARE phase produced ZERO vertices
+/// (ObjectMeshManager.cs:1780), so the upload is innocent — some extraction
+/// gate dropped every polygon. This dump prints the raw dat facts per polygon
+/// and replicates PrepareGfxObjMeshData's gates (ObjectMeshManager.cs:1040-1058)
+/// so the zeroing gate reads directly off the output.
+///
+public sealed class Issue119UpNullGfxObjDumpTests
+{
+ private readonly ITestOutputHelper _out;
+ public Issue119UpNullGfxObjDumpTests(ITestOutputHelper output) => _out = output;
+
+ public static readonly TheoryData UpNullIds = new() { 0x010002B4u, 0x010008A8u };
+
+ [Theory]
+ [MemberData(nameof(UpNullIds))]
+ public void DumpUpNullGfxObj(uint id)
+ {
+ var datDir = ConformanceDats.ResolveDatDir();
+ if (datDir is null) { _out.WriteLine("dats unavailable — skipped"); return; }
+ using var dats = new DatCollection(datDir, DatAccessType.Read);
+
+ Assert.True(dats.Portal.TryGet(id, out var gfx) && gfx is not null,
+ $"GfxObj 0x{id:X8} not in portal dat");
+
+ _out.WriteLine($"=== GfxObj 0x{id:X8} ===");
+ _out.WriteLine($"Flags={gfx!.Flags} Polygons={gfx.Polygons.Count} Vertices={gfx.VertexArray.Vertices.Count} Surfaces={gfx.Surfaces.Count}");
+ _out.WriteLine($"DrawingBSP={(gfx.DrawingBSP?.Root is null ? "NONE" : "present")} PhysicsBSP={(gfx.PhysicsBSP?.Root is null ? "NONE" : "present")}");
+
+ for (int i = 0; i < gfx.Surfaces.Count; i++)
+ {
+ uint sid = gfx.Surfaces[i];
+ string stype = dats.Portal.TryGet(sid, out var surf) && surf is not null
+ ? surf.Type.ToString()
+ : "MISSING";
+ _out.WriteLine($" surface[{i}] = 0x{sid:X8} type={stype}");
+ }
+
+ // Replicate the extraction gates (PrepareGfxObjMeshData):
+ // pos added when !NoPos
+ // neg added when Negative || Both || (!NoNeg && SidesType==Clockwise)
+ // surface index must be in [0, Surfaces.Count)
+ int wouldAddPos = 0, wouldAddNeg = 0, degenerate = 0;
+ var gateHistogram = new Dictionary();
+ foreach (var (pid, poly) in gfx.Polygons.OrderBy(kv => kv.Key))
+ {
+ string gate;
+ if (poly.VertexIds.Count < 3) { degenerate++; gate = "degenerate(<3 verts)"; }
+ else
+ {
+ bool pos = !poly.Stippling.HasFlag(StipplingType.NoPos)
+ && poly.PosSurface >= 0 && poly.PosSurface < gfx.Surfaces.Count;
+ bool neg = (poly.Stippling.HasFlag(StipplingType.Negative)
+ || poly.Stippling.HasFlag(StipplingType.Both)
+ || (!poly.Stippling.HasFlag(StipplingType.NoNeg) && poly.SidesType == CullMode.Clockwise))
+ && poly.NegSurface >= 0 && poly.NegSurface < gfx.Surfaces.Count;
+ if (pos) wouldAddPos++;
+ if (neg) wouldAddNeg++;
+ gate = pos || neg ? "DRAWS" : $"DROPPED stip={poly.Stippling} sides={poly.SidesType} posSurf={poly.PosSurface} negSurf={poly.NegSurface}";
+ }
+ gateHistogram.TryGetValue(gate, out int c);
+ gateHistogram[gate] = c + 1;
+ _out.WriteLine(FormattableString.Invariant(
+ $" poly[{pid}] verts={poly.VertexIds.Count} stip={poly.Stippling} sides={poly.SidesType} posSurf={poly.PosSurface} negSurf={poly.NegSurface} gate={gate}"));
+ }
+
+ _out.WriteLine($"--- summary: wouldAddPos={wouldAddPos} wouldAddNeg={wouldAddNeg} degenerate={degenerate} of {gfx.Polygons.Count} polys ---");
+ foreach (var (gate, count) in gateHistogram.OrderByDescending(kv => kv.Value))
+ _out.WriteLine($" {count,3} × {gate}");
+ }
+
+ ///
+ /// #119 second fact: does the extraction drop any polys that retail WOULD
+ /// draw (textured, non-solid surface) on a building-shell model? Run on the
+ /// Holtburg meeting-hall shell 0x010014C3 (the #113-saga tower whose stairs
+ /// are "regular shell polys" — render digest user axiom). A non-zero
+ /// "DROPPED but textured" count names the extraction as the stairs-miss
+ /// mechanism; zero exonerates the per-poly gates.
+ ///
+ [Theory]
+ [InlineData(0x010014C3u)]
+ public void ShellModel_NoTexturedPolyIsDropped(uint id)
+ {
+ var datDir = ConformanceDats.ResolveDatDir();
+ if (datDir is null) { _out.WriteLine("dats unavailable — skipped"); return; }
+ using var dats = new DatCollection(datDir, DatAccessType.Read);
+
+ Assert.True(dats.Portal.TryGet(id, out var gfx) && gfx is not null,
+ $"GfxObj 0x{id:X8} not in portal dat");
+
+ bool SurfaceIsTextured(short idx)
+ {
+ if (idx < 0 || idx >= gfx!.Surfaces.Count) return false;
+ if (!dats.Portal.TryGet(gfx.Surfaces[idx], out var surf) || surf is null) return false;
+ return !surf.Type.HasFlag(SurfaceType.Base1Solid);
+ }
+
+ int draws = 0;
+ var droppedTextured = new List();
+ foreach (var (pid, poly) in gfx!.Polygons.OrderBy(kv => kv.Key))
+ {
+ if (poly.VertexIds.Count < 3) continue;
+ bool pos = !poly.Stippling.HasFlag(StipplingType.NoPos)
+ && poly.PosSurface >= 0 && poly.PosSurface < gfx.Surfaces.Count;
+ bool neg = (poly.Stippling.HasFlag(StipplingType.Negative)
+ || poly.Stippling.HasFlag(StipplingType.Both)
+ || (!poly.Stippling.HasFlag(StipplingType.NoNeg) && poly.SidesType == CullMode.Clockwise))
+ && poly.NegSurface >= 0 && poly.NegSurface < gfx.Surfaces.Count;
+ if (pos || neg) { draws++; continue; }
+
+ // dropped by the gates — would retail have drawn a textured side?
+ if (SurfaceIsTextured(poly.PosSurface) || SurfaceIsTextured(poly.NegSurface))
+ droppedTextured.Add(FormattableString.Invariant(
+ $"poly[{pid}] stip={poly.Stippling} sides={poly.SidesType} posSurf={poly.PosSurface} negSurf={poly.NegSurface}"));
+ }
+
+ _out.WriteLine($"GfxObj 0x{id:X8}: polys={gfx.Polygons.Count} drawnByGates={draws} droppedTextured={droppedTextured.Count}");
+ foreach (var line in droppedTextured)
+ _out.WriteLine($" {line}");
+ Assert.True(droppedTextured.Count == 0,
+ $"{droppedTextured.Count} textured polys are dropped by the extraction gates on 0x{id:X8} — see output");
+ }
+}