fix(#186): render side-cull mis-sided thin connectors — use dat PortalSide bit, not AABB centroid

The indoor GREY flap at a top-floor connecting room. The render portal side-cull
reconstructed each doorway's "interior side" (PortalClipPlane.InsideSide) from the
cell's AABB CENTROID. For a THIN connector cell (0xF6820118, 5 render polys), the
bounding-box center falls on the WRONG side of the 0118->0116 doorway, so the eye
read as a back-portal and the forward room 0116 was culled -> the aperture showed
the fog clear color = grey.

Retail's PView::InitCell (0x005a4b70) and acdream's own PHYSICS path
(CellTransit.cs:190) both read the explicit dat PortalSide bit ((Flags&2)==0)
instead of guessing from geometry. Port the render path (GameWindow.BuildLoadedCell)
to the same bit.

Proven by a live retail cdb trace (retail draws 0116 from the 0118 root at the grey
pose; tools/cdb/issue186-connector-decider.cdb) + an offline dat diagnostic
(Issue186...PortalSide_CentroidVsDatBit_AtGreyEye): the dat bit matches the old
centroid on every portal of these cells EXCEPT the one #186 breaks, so the switch is
surgical. Full regression green (App 741 / Core 2631); the CornerFlood + Issue113
dat-loading helpers updated to the same bit confirm every real Holtburg/tower/hall
cell floods identically. Touches neither PortalSideEpsilon nor the deleted
EyeInsidePortalOpening rescue (the two DO-NOT-RETRY traps).

Live-gated: user-confirmed no grey at any camera angle; probe shows 216 root=0118
frames, 0 still grey (0118->0116 now TRV, vis=4).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/AcDream.App/Rendering/GameWindow.cs

@@ -7390,9 +7390,6 @@ public sealed class GameWindow : IDisposable
         var clipPlanes = new List<PortalClipPlane>();
         var portalPolygons = new List<System.Numerics.Vector3[]>();
 
-        // Compute cell centroid in local space for InsideSide determination.
-        var centroid = (boundsMin + boundsMax) * 0.5f;
-
         foreach (var portal in envCell.CellPortals)
         {
             portals.Add(new CellPortalInfo(
@@ -7426,10 +7423,19 @@ public sealed class GameWindow : IDisposable
                         System.Numerics.Vector3.Cross(p1 - p0, p2 - p0));
                     float d = -System.Numerics.Vector3.Dot(normal, p0);
 
-                    // Determine InsideSide: which side of the plane the cell centroid is on.
+                    // InsideSide from the dat PortalSide bit — retail PView::InitCell
-                    // If centroid dot > 0 → inside is positive half-space (InsideSide=0).
+                    // (0x005a4b70) gates traversal on `iVar9 != portals->portal_side`, and
-                    float centroidDot = System.Numerics.Vector3.Dot(normal, centroid) + d;
+                    // acdream's own physics path uses the same bit (CellTransit.cs:190).
-                    int insideSide = centroidDot >= 0 ? 0 : 1;
+                    // The former AABB-centroid reconstruction mis-derived the interior side
+                    // for THIN connector cells: the connector's bounding-box center falls on
+                    // the wrong side of a portal near the cell edge, so the eye read as a
+                    // back-portal and the forward room was culled — the #186 grey flap at
+                    // 0xF6820118→0116 (retail draws 0116 from that root; cdb-confirmed).
+                    // PortalSide (Flags&2)==0 → the portal polygon normal points INTO the
+                    // owning cell → interior is the negative half → InsideSide=1. Diagnostic
+                    // Issue186…PortalSide_CentroidVsDatBit_AtGreyEye: the dat bit matches the
+                    // centroid on every portal of these cells EXCEPT the one #186 breaks.
+                    int insideSide = ((ushort)portal.Flags & 0x2) == 0 ? 1 : 0;
 
                     clipPlanes.Add(new PortalClipPlane
                     {

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

@@ -88,7 +88,6 @@ public class CornerFloodReplayTests
         var portals = new List<CellPortalInfo>();
         var clipPlanes = new List<PortalClipPlane>();
         var portalPolygons = new List<Vector3[]>();
-        var centroid = (boundsMin + boundsMax) * 0.5f;
 
         foreach (var portal in envCell.CellPortals)
         {
@@ -106,10 +105,13 @@ public class CornerFloodReplayTests
                 var p2 = new Vector3(v2.Origin.X, v2.Origin.Y, v2.Origin.Z);
                 var normal = Vector3.Normalize(Vector3.Cross(p1 - p0, p2 - p0));
                 float d = -Vector3.Dot(normal, p0);
-                float centroidDot = Vector3.Dot(normal, centroid) + d;
+                // InsideSide from the dat PortalSide bit — mirrors the production fix
+                // (GameWindow.BuildLoadedCell): retail InitCell (0x005a4b70) + physics
+                // CellTransit use the dat bit; the old AABB-centroid guess mis-sided thin
+                // connectors (#186). Kept identical here so this replay stays a faithful mirror.
                 clipPlanes.Add(new PortalClipPlane
                 {
-                    Normal = normal, D = d, InsideSide = centroidDot >= 0 ? 0 : 1,
+                    Normal = normal, D = d, InsideSide = ((ushort)portal.Flags & 0x2) == 0 ? 1 : 0,
                 });
             }
             else

tests/AcDream.App.Tests/Rendering/Issue113MeetingHallFloodTests.cs

@@ -77,7 +77,6 @@ public class Issue113MeetingHallFloodTests
         var portals = new List<CellPortalInfo>();
         var clipPlanes = new List<PortalClipPlane>();
         var portalPolygons = new List<Vector3[]>();
-        var centroid = (boundsMin + boundsMax) * 0.5f;
 
         foreach (var portal in envCell.CellPortals)
         {
@@ -95,10 +94,13 @@ public class Issue113MeetingHallFloodTests
                 var p2 = new Vector3(v2.Origin.X, v2.Origin.Y, v2.Origin.Z);
                 var normal = Vector3.Normalize(Vector3.Cross(p1 - p0, p2 - p0));
                 float d = -Vector3.Dot(normal, p0);
-                float centroidDot = Vector3.Dot(normal, centroid) + d;
+                // InsideSide from the dat PortalSide bit — mirrors the production fix
+                // (GameWindow.BuildLoadedCell): retail InitCell (0x005a4b70) + physics
+                // CellTransit use the dat bit; the old AABB-centroid guess mis-sided thin
+                // connectors (#186). Kept identical here so this replay stays a faithful mirror.
                 clipPlanes.Add(new PortalClipPlane
                 {
-                    Normal = normal, D = d, InsideSide = centroidDot >= 0 ? 0 : 1,
+                    Normal = normal, D = d, InsideSide = ((ushort)portal.Flags & 0x2) == 0 ? 1 : 0,
                 });
             }
             else

tests/AcDream.Core.Tests/Physics/Issue186ConnectorCellGeometryInspectionTests.cs

@@ -78,6 +78,103 @@ public class Issue186ConnectorCellGeometryInspectionTests
         }
     }
 
+    /// <summary>
+    /// #186 root-cause probe (report-only): for every portal of the three connector
+    /// cells, reproduce acdream's RENDER side test (centroid-derived InsideSide,
+    /// GameWindow.cs:7425-7438 + PortalVisibilityBuilder.cs:857-864) and compare it to
+    /// the dat <c>PortalSide</c> bit that retail's PView::InitCell (0x005a4b70) and
+    /// acdream's own PHYSICS path (CellTransit.cs:190) use. Evaluates each at the live
+    /// retail/acdream grey-pose eye. The retail cdb trace proved retail ADMITS 0118->0116
+    /// at this eye; acdream CULLs it. This dump shows whether the centroid InsideSide
+    /// disagrees with the dat PortalSide for 0118->0116 (the fix) and AGREES elsewhere
+    /// (so the fix is surgical, not a global side-test change).
+    /// </summary>
+    [Fact]
+    public void PortalSide_CentroidVsDatBit_AtGreyEye()
+    {
+        var datDir = DatDir();
+        if (datDir is null) { _out.WriteLine("SKIP: no dat dir"); return; }
+        using var dats = new DatCollection(datDir, DatAccessType.Read);
+
+        // Live grey-pose eye (fresh HEAD capture + retail cdb trace both ~here).
+        var eyeWorld = new Vector3(135.51f, 83.32f, 69.16f);
+
+        var disagreements = new List<string>();          // portals where centroid != dat bit
+        bool sawConnectorBackPortal = false;             // the 0118->0116 case
+        bool connectorCentroidCulls = false, connectorDatAdmits = false;
+
+        foreach (uint cellId in new[] { 0xF6820116u, 0xF6820117u, 0xF6820118u })
+        {
+            var env = dats.Get<EnvCell>(cellId);
+            if (env is null) { _out.WriteLine($"cell 0x{cellId:X8}: EnvCell NOT FOUND"); continue; }
+            var environment = dats.Get<DatReaderWriter.DBObjs.Environment>(0x0D000000u | env.EnvironmentId);
+            if (environment is null || !environment.Cells.TryGetValue(env.CellStructure, out var cs) || cs is null)
+            { _out.WriteLine($"cell 0x{cellId:X8}: no CellStruct"); continue; }
+
+            var origin = new Vector3(env.Position.Origin.X, env.Position.Origin.Y, env.Position.Origin.Z);
+            var orient = new Quaternion(env.Position.Orientation.X, env.Position.Orientation.Y,
+                                        env.Position.Orientation.Z, env.Position.Orientation.W);
+            var world = Matrix4x4.CreateFromQuaternion(orient) * Matrix4x4.CreateTranslation(origin);
+            Matrix4x4.Invert(world, out var inverse);
+            var localEye = Vector3.Transform(eyeWorld, inverse);
+
+            // Centroid = AABB center over ALL cell verts (GameWindow.cs:7373-7394).
+            var bmin = new Vector3(float.MaxValue); var bmax = new Vector3(float.MinValue);
+            foreach (var kv in cs.VertexArray!.Vertices)
+            { var p = new Vector3(kv.Value.Origin.X, kv.Value.Origin.Y, kv.Value.Origin.Z);
+              bmin = Vector3.Min(bmin, p); bmax = Vector3.Max(bmax, p); }
+            var centroid = (bmin + bmax) * 0.5f;
+
+            _out.WriteLine($"=== cell 0x{cellId:X8}  localEye=({localEye.X:F2},{localEye.Y:F2},{localEye.Z:F2}) ===");
+            foreach (var portal in env.CellPortals!)
+            {
+                if (!cs.Polygons!.TryGetValue(portal.PolygonId, out var poly) || poly.VertexIds is null || poly.VertexIds.Count < 3)
+                { _out.WriteLine($"   p->0x{portal.OtherCellId:X4}: no poly"); continue; }
+                Vector3 V(int k) { var v = cs.VertexArray.Vertices[(ushort)poly.VertexIds[k]]; return new Vector3(v.Origin.X, v.Origin.Y, v.Origin.Z); }
+                var p0 = V(0); var p1 = V(1); var p2 = V(2);
+                var normal = Vector3.Normalize(Vector3.Cross(p1 - p0, p2 - p0));
+                float d = -Vector3.Dot(normal, p0);
+
+                float centroidDot = Vector3.Dot(normal, centroid) + d;
+                int centroidInside = centroidDot >= 0 ? 0 : 1;
+
+                ushort flags = (ushort)portal.Flags;
+                bool portalSide = (flags & 0x2) == 0;         // PortalInfo.cs:44 / CellPortal.cs:24
+                int datInside = portalSide ? 1 : 0;           // mapping derived from retail InitCell + physics CellTransit
+
+                float eyeDot = Vector3.Dot(normal, localEye) + d;
+                const float eps = 0.01f;
+                bool admitCentroid = centroidInside == 0 ? eyeDot >= -eps : eyeDot <= eps;
+                bool admitDat      = datInside     == 0 ? eyeDot >= -eps : eyeDot <= eps;
+
+                if (centroidInside != datInside)
+                    disagreements.Add($"0x{cellId & 0xFFFF:X4}->0x{portal.OtherCellId:X4}");
+                if (cellId == 0xF6820118u && portal.OtherCellId == 0x0116)
+                {
+                    sawConnectorBackPortal = true;
+                    connectorCentroidCulls = !admitCentroid;
+                    connectorDatAdmits = admitDat;
+                }
+
+                string flag = centroidInside != datInside ? "  <<< DISAGREE" : "";
+                string verdict = admitCentroid != admitDat ? $"  centroid={(admitCentroid ? "ADMIT" : "CULL")} dat={(admitDat ? "ADMIT" : "CULL")}" : "";
+                _out.WriteLine($"   p->0x{portal.OtherCellId:X4}  flags=0x{flags:X2} PortalSide={portalSide,-5} " +
+                               $"centroidInside={centroidInside} datInside={datInside}  eyeDot={eyeDot,7:F3}  " +
+                               $"admit[centroid={admitCentroid,-5} dat={admitDat,-5}]{flag}{verdict}");
+            }
+        }
+
+        // Root cause + fix pins (the retail cdb trace is the oracle: retail draws 0116
+        // from the 0118 root at this eye; acdream's centroid rule culled it → grey).
+        Assert.True(sawConnectorBackPortal, "0xF6820118->0116 portal not found in the dat");
+        Assert.True(connectorCentroidCulls, "the OLD centroid rule should CULL 0118->0116 at the grey eye (the bug)");
+        Assert.True(connectorDatAdmits, "the dat PortalSide bit should ADMIT 0118->0116 at the grey eye (the fix, matches retail)");
+        // Surgical: the ONLY portal across these three cells where the centroid rule
+        // disagrees with the dat bit is the one #186 breaks. If this list ever grows,
+        // the centroid→dat-bit switch is no longer a no-op for the working portals.
+        Assert.Equal(new[] { "0x0118->0x0116" }, disagreements.ToArray());
+    }
+
     private static Vector3? PolyNormal(DatReaderWriter.Types.Polygon poly, DatReaderWriter.Types.VertexArray va)
     {
         if (poly.VertexIds is null || poly.VertexIds.Count < 3) return null;

tools/cdb/issue186-connector-decider.cdb

@@ -0,0 +1,37 @@
+* #186 connector GREY flap - PICK-vs-FLOOD decider (2026-07-08)
+* Attach to a LIVE retail acclient.exe HELD in the connecting-room grey pose.
+* Binary MUST pair with refs/acclient.pdb (check_exe_pdb.py -> MATCH).
+*
+* Two breakpoints, both sampled at a low rate to avoid lagging retail -> ACE timeout:
+*   bp1 SmartBox::update_viewer (0x453ce0) -> viewer.objcell_id  = the render ROOT (viewer_cell)
+*                                             player m_position   = confirms we are at the pose (expect 0116)
+*   bp2 PView::DrawCells        (0x5a4840) -> cell_draw_num + cell_draw_list ids = the DRAWN cell set
+*                                             + eye viewpoint
+*
+* DECISION (handoff 2026-07-08-186 section 3):
+*   retail viewerCell == 0116                         -> PICK fix  (acdream over-switches root to connector 0118)
+*   retail viewerCell == 0118 AND draw list has 0116  -> FLOOD fix (retail keeps the back-portal room drawn)
+*
+* update_viewer sets viewer_cell at EXIT, so at bp ENTRY viewer.objcell_id is the PRIOR frame value.
+* For a HELD (stationary) pose prior==current, so this is exact - HOLD the grey pose.
+*
+* Auto-detach via .detach after a hit threshold (qd does NOT fire inside a conditional bp action - it
+* strands cdb and kills retail). NEVER put a semicolon inside a comment line (it splits into a command).
+
+.logopen C:\Users\erikn\source\repos\acdream\.claude\worktrees\vigorous-joliot-f0c3ad\issue186-connector-decider.log
+.sympath C:\Users\erikn\source\repos\acdream\refs
+.symopt+ 0x40
+.reload /f acclient.exe
+
+.echo ===SYMBOLS===
+x acclient!SmartBox::update_viewer
+x acclient!PView::DrawCells
+
+r $t0 = 0
+r $t1 = 0
+
+bp acclient!SmartBox::update_viewer "r $t0 = @$t0 + 1; .if (@$t0 % 15 == 1) { .printf \"[root] hit=%d viewerCell=%04x playerCell=%04x\\n\", @$t0, @@c++(((acclient!SmartBox*)@ecx)->viewer.objcell_id) & 0xffff, @@c++(((acclient!SmartBox*)@ecx)->player->m_position.objcell_id) & 0xffff }; gc"
+
+bp acclient!PView::DrawCells "r $t1 = @$t1 + 1; .if (@$t1 % 15 == 1) { r $t2 = @@c++(((acclient!PView*)@ecx)->cell_draw_num); .printf \"[draw] hit=%d num=%d:\", @$t1, @$t2; .for (r $t3 = 0; @$t3 < @$t2; r $t3 = @$t3 + 1) { .printf \" %04x\", @@c++(((acclient!PView*)@ecx)->cell_draw_list.data[@$t3]->m_DID.id) & 0xffff }; .printf \" || eye \"; dx acclient!Render::FrameCurrent->viewer.viewpoint }; .if (@$t1 >= 3000) { .detach } .else { gc }"
+
+g

tools/cdb/run-issue186-decider.ps1

@@ -0,0 +1,7 @@
+# Attach cdb to a live retail acclient.exe and run the #186 connector decider script.
+# Prereq: retail is already in-world (user walked to the connecting room, holding the grey pose).
+# Verify pairing first:  py tools/pdb-extract/check_exe_pdb.py "C:/Turbine/Asheron's Call/acclient.exe"
+$cdb    = "C:\Program Files (x86)\Windows Kits\10\Debuggers\x86\cdb.exe"
+$script = "C:\Users\erikn\source\repos\acdream\.claude\worktrees\vigorous-joliot-f0c3ad\tools\cdb\issue186-connector-decider.cdb"
+$tee    = "C:\Users\erikn\source\repos\acdream\.claude\worktrees\vigorous-joliot-f0c3ad\issue186-connector-decider.console.log"
+& $cdb -pn acclient.exe -cf $script *>&1 | Tee-Object -FilePath $tee