refactor(world): extract live projection mechanics

Move appearance rebinding, collision construction, default-pose resolution, local shadow ownership, and exact leave-world presentation into focused owners. Preserve retail parent ordering with staged validation, committed recovery, recursive attached-subtree withdrawal, and retryable exact teardown across parent, pickup, position, unwield, and pose-loss edges.

Co-Authored-By: OpenAI Codex <codex@openai.com>

src/AcDream.App/Rendering/LiveEntityAppearanceBinding.cs

@@ -0,0 +1,127 @@
+using System.Numerics;
+using AcDream.App.Physics;
+using AcDream.App.World;
+using AcDream.Core.Net;
+using AcDream.Core.Physics;
+using AcDream.Core.World;
+using DatReaderWriter.DBObjs;
+
+namespace AcDream.App.Rendering;
+
+/// <summary>
+/// Exact runtime identity retained while retail
+/// <c>SmartBox::UpdateVisualDesc</c> mutates only a live object's visual
+/// description.
+/// </summary>
+internal sealed record LiveEntityAppearanceUpdateState(
+    WorldEntity Entity,
+    LiveEntityAnimationState? Animation);
+
+internal sealed record LiveEntityAppearanceCollisionUpdate(
+    LiveEntityRecord Record,
+    WorldEntity Entity,
+    LiveEntityCollisionRegistration? Registration);
+
+/// <summary>
+/// Focused appearance-lifetime operations shared by ObjDesc hydration and the
+/// final animation presenter. This type owns no identity index; every capture
+/// is resolved from <see cref="LiveEntityRuntime"/>.
+/// </summary>
+internal static class LiveEntityAppearanceBinding
+{
+    public static LiveEntityAppearanceUpdateState? Capture(
+        LiveEntityRuntime runtime,
+        uint serverGuid)
+    {
+        ArgumentNullException.ThrowIfNull(runtime);
+        if (!runtime.TryGetRecord(serverGuid, out LiveEntityRecord record)
+            || record.WorldEntity is not { } entity)
+        {
+            return null;
+        }
+
+        return new LiveEntityAppearanceUpdateState(
+            entity,
+            record.AnimationRuntime as LiveEntityAnimationState);
+    }
+
+    public static void RebindAnimation(
+        LiveEntityAnimationState animation,
+        WorldEntity entity,
+        Setup setup,
+        float scale,
+        IReadOnlyList<LiveAnimationPartTemplate> partTemplate,
+        IReadOnlyList<bool> partAvailability)
+    {
+        ArgumentNullException.ThrowIfNull(animation);
+        ArgumentNullException.ThrowIfNull(entity);
+        ArgumentNullException.ThrowIfNull(setup);
+        ArgumentNullException.ThrowIfNull(partTemplate);
+        ArgumentNullException.ThrowIfNull(partAvailability);
+
+        animation.Entity = entity;
+        animation.Setup = setup;
+        animation.Scale = scale;
+        animation.PartTemplate = partTemplate;
+        animation.PartAvailability = partAvailability;
+        animation.InvalidatePresentationPoses();
+    }
+
+    public static LiveEntityAppearanceCollisionUpdate? PrepareCollision(
+        LiveEntityRuntime runtime,
+        LiveEntityCollisionBuilder builder,
+        WorldEntity entity,
+        Setup setup,
+        IReadOnlyList<uint> effectivePartGfxObjIds,
+        WorldSession.EntitySpawn spawn,
+        Vector3 worldOrigin)
+    {
+        ArgumentNullException.ThrowIfNull(runtime);
+        ArgumentNullException.ThrowIfNull(builder);
+        ArgumentNullException.ThrowIfNull(entity);
+        ArgumentNullException.ThrowIfNull(setup);
+        ArgumentNullException.ThrowIfNull(effectivePartGfxObjIds);
+        if (!runtime.TryGetRecord(spawn.Guid, out LiveEntityRecord record)
+            || !ReferenceEquals(record.WorldEntity, entity))
+        {
+            return null;
+        }
+
+        return new LiveEntityAppearanceCollisionUpdate(
+            record,
+            entity,
+            builder.Build(
+                entity,
+                setup,
+                effectivePartGfxObjIds,
+                spawn,
+                record,
+                worldOrigin,
+                retainEmptyPayload: true));
+    }
+
+    public static bool CommitCollision(
+        LiveEntityRuntime runtime,
+        ShadowObjectRegistry registry,
+        LiveEntityAppearanceCollisionUpdate update)
+    {
+        ArgumentNullException.ThrowIfNull(runtime);
+        ArgumentNullException.ThrowIfNull(registry);
+        ArgumentNullException.ThrowIfNull(update);
+        if (!runtime.TryGetRecord(update.Record.ServerGuid, out LiveEntityRecord current)
+            || !ReferenceEquals(current, update.Record)
+            || !ReferenceEquals(current.WorldEntity, update.Entity))
+        {
+            return false;
+        }
+
+        LiveEntityCollisionBuilder.ReconcileAppearance(
+            registry,
+            update.Entity.Id,
+            update.Registration,
+            suspendIfNew: !current.IsSpatiallyVisible
+                || current.ProjectionKind is not LiveEntityProjectionKind.World
+                || (current.FinalPhysicsState & PhysicsStateFlags.Hidden) != 0);
+        return true;
+    }
+}