diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index 8e0fa7b..2b673bc 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -2127,6 +2127,14 @@ public sealed class GameWindow : IDisposable
         }
     }
 
+    /// <summary>
+    /// Phase B.4c — door detection by server-sent name. Doors fail the
+    /// generic multi-frame-idle gate at line 2692 (no idle cycle), so we
+    /// register them via a sibling branch with a state-seeded sequencer.
+    /// </summary>
+    private static bool IsDoorSpawn(AcDream.Core.Net.WorldSession.EntitySpawn spawn)
+        => spawn.Name == "Door";
+
     private void OnLiveEntitySpawnedLocked(AcDream.Core.Net.WorldSession.EntitySpawn spawn)
     {
         _liveSpawnReceived++;
@@ -2798,6 +2806,61 @@ public sealed class GameWindow : IDisposable
                     _entitySoundTables.Set(entity.Id, soundTableId);
             }
         }
+        else if (IsDoorSpawn(spawn) && _animLoader is not null)
+        {
+            // Phase B.4c — Door swing animation. Doors fail the
+            // multi-frame-idle gate above (no idle cycle) but DO have a
+            // MotionTable with On/Off cycles that ACE drives via
+            // UpdateMotion. Register with a seeded sequencer so the
+            // per-frame tick has frames to advance from frame 1 (without
+            // the seed, Sequencer.Advance(dt) returns no frames and the
+            // MeshRefs rebuild at line 7691 collapses the door to origin).
+            //
+            // Initial cycle mirrors ACE's Door.cs:43
+            // (CurrentMotionState = motionClosed): Off when the door is
+            // closed at spawn, On when the spawn PhysicsState carries the
+            // ETHEREAL bit (door was already open in ACE's DB).
+            uint mtableId = spawn.MotionTableId ?? (uint)setup.DefaultMotionTable;
+            if (mtableId != 0)
+            {
+                var mtable = _dats.Get<DatReaderWriter.DBObjs.MotionTable>(mtableId);
+                if (mtable is not null)
+                {
+                    var sequencer = new AcDream.Core.Physics.AnimationSequencer(setup, mtable, _animLoader);
+
+                    const uint NonCombatStance = 0x80000001u;
+                    const uint MotionOn = 0x4000000Bu;   // ACE MotionCommand.On (door open)
+                    const uint MotionOff = 0x4000000Cu;  // ACE MotionCommand.Off (door closed)
+                    const uint EtherealPs = 0x4u;
+                    uint spawnState = spawn.PhysicsState ?? 0u;
+                    uint initialCycle = (spawnState & EtherealPs) != 0 ? MotionOn : MotionOff;
+                    if (sequencer.HasCycle(NonCombatStance, initialCycle))
+                        sequencer.SetCycle(NonCombatStance, initialCycle);
+
+                    var template = new (uint, IReadOnlyDictionary<uint, uint>?)[meshRefs.Count];
+                    for (int i = 0; i < meshRefs.Count; i++)
+                        template[i] = (meshRefs[i].GfxObjId, meshRefs[i].SurfaceOverrides);
+
+                    _animatedEntities[entity.Id] = new AnimatedEntity
+                    {
+                        Entity = entity,
+                        Setup = setup,
+                        Animation = null!,           // sequencer-driven; tick reads sequencer state
+                        LowFrame = 0,
+                        HighFrame = 0,
+                        Framerate = 0f,
+                        Scale = scale,
+                        PartTemplate = template,
+                        CurrFrame = 0,
+                        Sequencer = sequencer,
+                    };
+
+                    if (AcDream.Core.Physics.PhysicsDiagnostics.ProbeBuildingEnabled)
+                        Console.WriteLine(System.FormattableString.Invariant(
+                            $"[door-anim] registered guid=0x{spawn.Guid:X8} entityId=0x{entity.Id:X8} mtable=0x{mtableId:X8} initialCycle=0x{initialCycle:X8}"));
+                }
+            }
+        }
 
         // Dump a summary periodically so we can see drop breakdowns without
         // waiting for a graceful shutdown.