feat(combat): port retail held weapon parenting

Select the default combat mode from ordered equipped objects so bows request missile stance. Parse CreateObject parent metadata and ParentEvent, then render held objects as separate children composed from setup holding locations and placement frames each animation tick.

src/AcDream.Core.Net/Messages/CreateObject.cs

@@ -122,6 +122,12 @@ public static class CreateObject
         // L.2g S1 (DEV-6): ObjectMovement stamp (timestamp block index 1)
         // seeds MotionSequenceGate's MOVEMENT_TS at spawn.
         ushort MovementSequence = 0,
+        // Parent/placement bootstrap for equipped child objects. These are
+        // the CreateObject equivalents of ParentEvent 0xF749.
+        ushort PositionSequence = 0,
+        uint? ParentGuid = null,
+        uint? ParentLocation = null,
+        uint? PlacementId = null,
         uint? PhysicsState = null,
         uint? ObjectDescriptionFlags = null,
         // L.3b (2026-04-30): per-object friction + elasticity from the
@@ -522,6 +528,10 @@ public static class CreateObject
             physicsState = BinaryPrimitives.ReadUInt32LittleEndian(body.Slice(pos));
             pos += 4;
 
+            uint? placementId = null;
+            uint? parentGuid = null;
+            uint? parentLocation = null;
+
             if ((physicsFlags & PhysicsDescriptionFlag.Movement) != 0)
             {
                 // u32 length, length bytes of serialized MovementData (no header
@@ -543,6 +553,7 @@ public static class CreateObject
             else if ((physicsFlags & PhysicsDescriptionFlag.AnimationFrame) != 0)
             {
                 if (body.Length - pos < 4) return null;
+                placementId = BinaryPrimitives.ReadUInt32LittleEndian(body.Slice(pos));
                 pos += 4;
             }
 
@@ -593,7 +604,9 @@ public static class CreateObject
             if ((physicsFlags & PhysicsDescriptionFlag.Parent) != 0)
             {
                 if (body.Length - pos < 8) return null;
-                pos += 8;  // wielderId u32 + parentLocation u32
+                parentGuid = BinaryPrimitives.ReadUInt32LittleEndian(body.Slice(pos));
+                parentLocation = BinaryPrimitives.ReadUInt32LittleEndian(body.Slice(pos + 4));
+                pos += 8;
             }
             if ((physicsFlags & PhysicsDescriptionFlag.Children) != 0)
             {
@@ -643,6 +656,7 @@ public static class CreateObject
             if (body.Length - pos < 9 * 2) return PartialResult();
             var seqSpan = body.Slice(pos, 9 * 2);
             ushort instanceSeq       = BinaryPrimitives.ReadUInt16LittleEndian(seqSpan.Slice(8 * 2));
+            ushort positionSeq       = BinaryPrimitives.ReadUInt16LittleEndian(seqSpan.Slice(0 * 2));
             ushort movementSeq       = BinaryPrimitives.ReadUInt16LittleEndian(seqSpan.Slice(1 * 2));
             ushort teleportSeq       = BinaryPrimitives.ReadUInt16LittleEndian(seqSpan.Slice(4 * 2));
             ushort serverControlSeq  = BinaryPrimitives.ReadUInt16LittleEndian(seqSpan.Slice(5 * 2));
@@ -984,8 +998,14 @@ public static class CreateObject
                 textureChanges, subPalettes, basePaletteId, objScale, name, itemType, motionState, motionTableId,
                 instanceSeq, teleportSeq, serverControlSeq, forcePositionSeq,
                 movementSeq,
-                physicsState, objectDescriptionFlags,
-                friction, elasticity,
+                PositionSequence: positionSeq,
+                ParentGuid: parentGuid,
+                ParentLocation: parentLocation,
+                PlacementId: placementId,
+                PhysicsState: physicsState,
+                ObjectDescriptionFlags: objectDescriptionFlags,
+                Friction: friction,
+                Elasticity: elasticity,
                 IconId: iconId,
                 Useability: useability, UseRadius: useRadius, TargetType: targetType,
                 IconOverlayId: iconOverlayId, IconUnderlayId: iconUnderlayId,

src/AcDream.Core.Net/Messages/ParentEvent.cs

@@ -0,0 +1,42 @@
+using System.Buffers.Binary;
+
+namespace AcDream.Core.Net.Messages;
+
+/// <summary>
+/// Inbound retail <c>ParentEvent</c> (<c>0xF749</c>): attach a child physics
+/// object (weapon, shield, ammunition) to a named holding location on a
+/// parent creature and apply the child's placement frame.
+///
+/// Wire oracle: <c>CM_Physics::DispatchSB_ParentEvent @ 0x006ACAF0</c>.
+/// Runtime oracle: <c>SmartBox::HandleParentEvent @ 0x004535D0</c> and
+/// <c>SmartBox::DoParentEvent @ 0x00452290</c>.
+/// </summary>
+public static class ParentEvent
+{
+    public const uint Opcode = 0xF749u;
+
+    public readonly record struct Parsed(
+        uint ParentGuid,
+        uint ChildGuid,
+        uint ParentLocation,
+        uint PlacementId,
+        ushort ParentInstanceSequence,
+        ushort ChildPositionSequence);
+
+    public static Parsed? TryParse(ReadOnlySpan<byte> body)
+    {
+        if (body.Length < 24)
+            return null;
+
+        if (BinaryPrimitives.ReadUInt32LittleEndian(body) != Opcode)
+            return null;
+
+        return new Parsed(
+            BinaryPrimitives.ReadUInt32LittleEndian(body.Slice(4, 4)),
+            BinaryPrimitives.ReadUInt32LittleEndian(body.Slice(8, 4)),
+            BinaryPrimitives.ReadUInt32LittleEndian(body.Slice(12, 4)),
+            BinaryPrimitives.ReadUInt32LittleEndian(body.Slice(16, 4)),
+            BinaryPrimitives.ReadUInt16LittleEndian(body.Slice(20, 2)),
+            BinaryPrimitives.ReadUInt16LittleEndian(body.Slice(22, 2)));
+    }
+}