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+## AvatarSlotRegistry - Static registry of slot definitions.
+##
+## Each slot maps to one or more bones and defines what can be equipped there.
+## This is the single source of truth for slot IDs, categories, mount bones,
+## exclusivity, and body-part vs attachment classification.
+##
+## See docs/architecture/avatar.md §3.2 for the full slot specification.
+class_name AvatarSlotRegistry extends RefCounted
+
+
+# ---------------------------------------------------------------------------
+# Slot definitions (mirrors §3.2 of the avatar spec)
+# ---------------------------------------------------------------------------
+
+## All known slot IDs, in canonical order.
+const SLOT_IDS: PackedStringArray = [
+	"head",
+	"hair",
+	"face",
+	"torso",
+	"chest",
+	"back",
+	"left_arm",
+	"right_arm",
+	"left_hand",
+	"right_hand",
+	"legs",
+	"pants",
+	"left_foot",
+	"right_foot",
+	"accessory",
+]
+
+## Body-part slots (exclusive, replace base mesh).
+const BODY_PART_SLOTS: PackedStringArray = [
+	"head", "torso", "legs", "left_arm", "right_arm",
+]
+
+## Attachment slots (layered on top of base mesh).
+const ATTACHMENT_SLOTS: PackedStringArray = [
+	"hair", "face", "chest", "back",
+	"left_hand", "right_hand", "pants",
+	"left_foot", "right_foot", "accessory",
+]
+
+## Slots that are multi-slot (multiple accessories can coexist).
+const MULTI_SLOT_IDS: PackedStringArray = ["accessory"]
+
+
+# Slot metadata lookup tables (indexed by SLOT_IDS position).
+# Each entry: { category, mount_bones, exclusive, is_body_part }
+var _slot_data: Dictionary = {}
+
+
+func _init() -> void:
+	_build_registry()
+
+
+func _build_registry() -> void:
+	_slot_data = {
+		"head": {
+			"category": "body_part",
+			"mount_bones": ["Head"],
+			"exclusive": true,
+			"is_body_part": true,
+		},
+		"hair": {
+			"category": "attachment",
+			"mount_bones": ["HeadTop"],
+			"exclusive": true,
+			"is_body_part": false,
+		},
+		"face": {
+			"category": "attachment",
+			"mount_bones": ["Jaw"],
+			"exclusive": true,
+			"is_body_part": false,
+		},
+		"torso": {
+			"category": "body_part",
+			"mount_bones": ["Chest"],
+			"exclusive": true,
+			"is_body_part": true,
+		},
+		"chest": {
+			"category": "attachment",
+			"mount_bones": ["Chest"],
+			"exclusive": true,
+			"is_body_part": false,
+		},
+		"back": {
+			"category": "attachment",
+			"mount_bones": ["Chest"],
+			"exclusive": true,
+			"is_body_part": false,
+		},
+		"left_arm": {
+			"category": "body_part",
+			"mount_bones": ["LeftUpperArm"],
+			"exclusive": true,
+			"is_body_part": true,
+		},
+		"right_arm": {
+			"category": "body_part",
+			"mount_bones": ["RightUpperArm"],
+			"exclusive": true,
+			"is_body_part": true,
+		},
+		"left_hand": {
+			"category": "attachment",
+			"mount_bones": ["LeftHand"],
+			"exclusive": true,
+			"is_body_part": false,
+		},
+		"right_hand": {
+			"category": "attachment",
+			"mount_bones": ["RightHand"],
+			"exclusive": true,
+			"is_body_part": false,
+		},
+		"legs": {
+			"category": "body_part",
+			"mount_bones": ["Hips"],
+			"exclusive": true,
+			"is_body_part": true,
+		},
+		"pants": {
+			"category": "attachment",
+			"mount_bones": ["Hips"],
+			"exclusive": true,
+			"is_body_part": false,
+		},
+		"left_foot": {
+			"category": "attachment",
+			"mount_bones": ["LeftFoot"],
+			"exclusive": true,
+			"is_body_part": false,
+		},
+		"right_foot": {
+			"category": "attachment",
+			"mount_bones": ["RightFoot"],
+			"exclusive": true,
+			"is_body_part": false,
+		},
+		"accessory": {
+			"category": "attachment",
+			"mount_bones": ["Root"],
+			"exclusive": false,
+			"is_body_part": false,
+		},
+	}
+
+
+# ---------------------------------------------------------------------------
+# Public API
+# ---------------------------------------------------------------------------
+
+## Returns the list of all known slot IDs.
+static func get_slot_ids() -> PackedStringArray:
+	return SLOT_IDS
+
+
+## Returns true if *slot_id* is a known slot.
+static func has_slot(slot_id: String) -> bool:
+	return slot_id in SLOT_IDS
+
+
+## Returns the category for a slot ("body_part" or "attachment").
+static func get_category(slot_id: String) -> String:
+	if not has_slot(slot_id):
+		push_error("AvatarSlotRegistry: unknown slot '%s'" % slot_id)
+		return ""
+	return _slot_data[slot_id]["category"]
+
+
+## Returns the primary mount bone(s) for a slot.
+static func get_mount_bones(slot_id: String) -> PackedStringArray:
+	if not has_slot(slot_id):
+		push_error("AvatarSlotRegistry: unknown slot '%s'" % slot_id)
+		return PackedStringArray()
+	return PackedStringArray(_slot_data[slot_id]["mount_bones"])
+
+
+## Returns whether the slot is exclusive (at most one item).
+static func is_exclusive(slot_id: String) -> bool:
+	if not has_slot(slot_id):
+		push_error("AvatarSlotRegistry: unknown slot '%s'" % slot_id)
+		return true
+	return _slot_data[slot_id]["exclusive"]
+
+
+## Returns whether the slot is a body-part slot (replaces base mesh).
+static func is_body_part_slot(slot_id: String) -> bool:
+	if not has_slot(slot_id):
+		push_error("AvatarSlotRegistry: unknown slot '%s'" % slot_id)
+		return false
+	return _slot_data[slot_id]["is_body_part"]
+
+
+## Returns whether the slot is a multi-slot (e.g. accessory).
+static func is_multi_slot(slot_id: String) -> bool:
+	return slot_id in MULTI_SLOT_IDS
+
+
+## Returns the list of body-part slot IDs.
+static func get_body_part_slots() -> PackedStringArray:
+	return BODY_PART_SLOTS
+
+
+## Returns the list of attachment slot IDs.
+static func get_attachment_slots() -> PackedStringArray:
+	return ATTACHMENT_SLOTS
+
+
+## Validates that an asset's declared slot matches the slot it is placed in.
+static func validate_slot_assignment(asset_slot: String, slot_id: String) -> bool:
+	return asset_slot == slot_id
+
+
+## Returns the canonical order index for a slot (for serialization order).
+static func get_slot_index(slot_id: String) -> int:
+	return SLOT_IDS.find(slot_id)