WIP checkpoint: fix static registry, uint32 type, GLTF API calls, ARRAY_BONES, missing slot handler

- avatar_slot_registry.gd: _slot_data/_slot_definitions made static (every
  caller uses AvatarSlotRegistry.method() on the class, never an instance,
  so the old instance _init() populating them was never invoked); moved
  registry build to static func _static_init()
- avatar_catalog.gd: compute_loadout_hash() return type uint32 -> int
  (GDScript has no fixed-width uint type)
- avatar_loader.gd: GLTFDocument.parse() (doesn't exist) -> the real
  append_from_buffer()+generate_scene() API; Error.parse_error() (doesn't
  exist) -> error_string(); Mesh.ARRAY_JOINTS (doesn't exist) ->
  Mesh.ARRAY_BONES; removed a dead 'mesh is MultiMesh' check that can
  never be true (MeshInstance3D.mesh is always Mesh, never MultiMesh);
  fixed _merge_node_into_avatar to recurse into a Skeleton3D's children
  (skinned meshes are commonly children of the skeleton in a GLB export,
  the old code returned before ever reaching them)
- avatar_customization_ui.gd: added the missing _on_slot_button_pressed
  handler (referenced by a button connect, never defined -- just calls
  the existing _select_slot())

Verified: godot --headless --import + --quit is fully clean, and the
avatar_customization.tscn scene now instantiates successfully.

Remaining, scoped separately: avatar_visualizer.gd calls a
AvatarLoader.load_slot() static async API and SlotItem/SlotResult types
that don't exist -- AvatarLoader's real API (matching the project's own
avatar.md spec: one canonical skeleton, attachments retargeted onto it)
is instance-based load_base_body()/load_attachment(). AvatarVisualizer
needs rewriting to use that real API; it's the one out of step with spec,
not AvatarLoader.

scripts/avatar/avatar_catalog.gd

@@ -156,8 +156,9 @@ func validate_loadout(loadout: AvatarLoadout) -> Dictionary:
 
 
 ## Compute a hash of the loadout for change detection.
-## Returns a uint32 hash.
+## Returns a 32-bit hash value (GDScript has no fixed-width uint type — int
-static func compute_loadout_hash(loadout: AvatarLoadout) -> uint32:
+## is 64-bit signed, the value is just constrained to 32 bits of range).
+static func compute_loadout_hash(loadout: AvatarLoadout) -> int:
 	var hasher = HashingContext.new()
 	hasher.start(HashingContext.HASH_SHA256)
 

scripts/avatar/avatar_customization_ui.gd

@@ -326,6 +326,11 @@ func _populate_items() -> void:
 # Slot selection
 # ---------------------------------------------------------------------------
 
+## Handle a slot button press.
+func _on_slot_button_pressed(slot_id: String) -> void:
+	_select_slot(slot_id)
+
+
 ## Select a slot and refresh the item list.
 func _select_slot(slot_id: String) -> void:
 	_selected_slot = slot_id

scripts/avatar/avatar_loader.gd

@@ -305,28 +305,26 @@ func _parse_glb_as_avatar(glb_data: PackedByteArray, path: String) -> Node3D:
 	avatar.add_child(attachments_container)
 
 	# Parse the GLB and extract skeleton + meshes.
-	# Godot's GLTFState allows custom parsing.
 	var gltf_document := GLTFDocument.new()
 	var gltf_state := GLTFState.new()
 
-	var parse_result := gltf_document.parse(glb_data, gltf_state, "", "")
+	var parse_result := gltf_document.append_from_buffer(glb_data, "", gltf_state)
 	if parse_result != OK:
-		push_error("GLB parse error: %s" % Error.parse_error(parse_result))
+		push_error("GLB parse error: %s" % error_string(parse_result))
 		avatar.queue_free()
 		return null
 
-	# Export the scene from GLTFState.
+	# Generate the actual scene tree from the parsed GLTF state.
-	var root_nodes := gltf_state.get_nodes_as_resources()
+	var scene_root := gltf_document.generate_scene(gltf_state)
-	if root_nodes.is_empty():
+	if scene_root == null:
-		push_error("No root nodes in GLB: %s" % path)
+		push_error("Failed to generate scene from GLB: %s" % path)
 		avatar.queue_free()
 		return null
 
-	# Merge GLB nodes into our avatar structure.
+	# Merge GLB nodes into our avatar structure (recurses into children).
-	for node_resource in root_nodes:
+	if scene_root is Node3D:
-		if node_resource is Node3D:
+		_merge_node_into_avatar(scene_root, avatar, body_meshes,
-			_merge_node_into_avatar(node_resource, avatar, body_meshes,
+			attach_points, attachments_container)
-				attach_points, attachments_container)
 
 	return avatar
 
@@ -338,22 +336,21 @@ func _parse_glb_as_attachment(glb_data: PackedByteArray, path: String,
 	var gltf_document := GLTFDocument.new()
 	var gltf_state := GLTFState.new()
 
-	var parse_result := gltf_document.parse(glb_data, gltf_state, "", "")
+	var parse_result := gltf_document.append_from_buffer(glb_data, "", gltf_state)
 	if parse_result != OK:
-		push_error("GLB parse error: %s" % Error.parse_error(parse_result))
+		push_error("GLB parse error: %s" % error_string(parse_result))
 		return null
 
-	var root_nodes := gltf_state.get_nodes_as_resources()
+	var scene_root := gltf_document.generate_scene(gltf_state)
-	if root_nodes.is_empty():
+	if scene_root == null:
-		push_error("No root nodes in attachment GLB: %s" % path)
+		push_error("Failed to generate scene from attachment GLB: %s" % path)
 		return null
 
 	var attachment := Node3D.new()
 	attachment.name = "%s_%s" % [slot_id, path.get_file().get_basename()]
 
-	for node_resource in root_nodes:
+	if scene_root is Node3D:
-		if node_resource is Node3D:
+		attachment.add_child(scene_root.duplicate())
-			attachment.add_child(node_resource.duplicate())
 
 	return attachment
 
@@ -392,6 +389,13 @@ func _merge_node_into_avatar(node: Node3D, avatar: Node3D,
 						var dst_parent_idx := dst_skel.find_bone(parent_name)
 						if dst_parent_idx >= 0:
 							dst_skel.set_bone_parent(new_idx, dst_parent_idx)
+		# Skinned meshes are commonly children of the skeleton node in a GLB
+		# export, not siblings — fall through to the recursion below instead
+		# of returning, so they still get merged in.
+		for child in src_skel.get_children():
+			if child is Node3D:
+				_merge_node_into_avatar(child, avatar, body_meshes,
+					attach_points, attachments_container)
 		return
 
 	# Identify attachment point nodes (empty nodes named attach_*).
@@ -468,18 +472,16 @@ func _retarget_skin(attachment_node: Node3D) -> void:
 			if mesh == null:
 				continue
 
-			# Handle MultiMeshInstance3D.
+			# Note: MeshInstance3D.mesh is always a Mesh, never a MultiMesh —
-			if mesh is MultiMesh:
+			# MultiMesh skinning goes through MultiMeshInstance3D.multimesh,
-				# MultiMesh doesn't have skin weights per-vertex in the same way.
+			# a completely separate node/property, not reachable here.
-				continue
-
 			if mesh is ArrayMesh:
 				var arr_mesh := mesh as ArrayMesh
 				var surface_count := arr_mesh.get_surface_count()
 
 				for surface_idx in surface_count:
 					var arrays := arr_mesh.surface_get_arrays(surface_idx)
-					var joints_array := arrays[Mesh.ARRAY_JOINTS] as PackedInt32Array
+					var joints_array := arrays[Mesh.ARRAY_BONES] as PackedInt32Array
 					var weights_array := arrays[Mesh.ARRAY_WEIGHTS] as PackedFloat32Array
 
 					if joints_array.is_empty():
@@ -494,10 +496,10 @@ func _retarget_skin(attachment_node: Node3D) -> void:
 								new_joints.append(0)
 							else:
 								var bone_name := skeleton.get_bone_name(old_joint)
-								var new_idx := _bone_index_map.get(bone_name, 0)
+								var new_idx: int = _bone_index_map.get(bone_name, 0)
 								new_joints.append(new_idx)
 
-					arrays[Mesh.ARRAY_JOINTS] = new_joints
+					arrays[Mesh.ARRAY_BONES] = new_joints
 					arr_mesh.surface_set_arrays(surface_idx, arrays)
 
 

scripts/avatar/avatar_slot_registry.gd

@@ -69,17 +69,20 @@ class SlotDefinition:
 		is_body_part = p_is_body_part
 
 
-# Slot metadata lookup tables (indexed by SLOT_IDS position).
+# Slot metadata lookup tables (indexed by SLOT_IDS position). Static: every
+# caller uses AvatarSlotRegistry.method(...) directly on the class, never on
+# an instance, so this data has to be built once at class-load time via
+# _static_init() rather than an instance _init() that's never invoked.
 # Each entry: { category, mount_bones, exclusive, is_body_part }
-var _slot_data: Dictionary = {}
+static var _slot_data: Dictionary = {}
-var _slot_definitions: Array[SlotDefinition] = []
+static var _slot_definitions: Array[SlotDefinition] = []
 
 
-func _init() -> void:
+static func _static_init() -> void:
 	_build_registry()
 
 
-func _build_registry() -> void:
+static func _build_registry() -> void:
 	_slot_data = {
 		"head": {
 			"category": "body_part",