refactor(M03): extract WMO placement registry

src/render/wmo/wmo_placement_registry.gd

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+class_name WmoPlacementRegistry
+extends RefCounted
+
+## Owns WMO placement-key to tile/global reference-key sets without Nodes.
+
+var _reference_keys_by_placement_key: Dictionary = {}
+
+
+## Adds one idempotent reference and returns true only for a newly registered
+## placement key. Empty placement/reference keys are rejected.
+func add_reference(placement_key: String, reference_key: String) -> bool:
+	if placement_key.is_empty() or reference_key.is_empty():
+		return false
+	var is_new_placement := not _reference_keys_by_placement_key.has(placement_key)
+	if is_new_placement:
+		_reference_keys_by_placement_key[placement_key] = {}
+	var reference_keys: Dictionary = _reference_keys_by_placement_key[placement_key]
+	reference_keys[reference_key] = true
+	return is_new_placement
+
+
+## Releases one reference and returns true only when the final reference removes
+## the placement key. Unknown and non-owner references leave state unchanged.
+func release_reference(placement_key: String, reference_key: String) -> bool:
+	if placement_key.is_empty() or reference_key.is_empty():
+		return false
+	if not _reference_keys_by_placement_key.has(placement_key):
+		return false
+	var reference_keys: Dictionary = _reference_keys_by_placement_key[placement_key]
+	if not reference_keys.has(reference_key):
+		return false
+	reference_keys.erase(reference_key)
+	if not reference_keys.is_empty():
+		return false
+	_reference_keys_by_placement_key.erase(placement_key)
+	return true
+
+
+## Returns whether the placement key currently has at least one reference.
+func contains(placement_key: String) -> bool:
+	return not placement_key.is_empty() and _reference_keys_by_placement_key.has(placement_key)
+
+
+## Removes every placement/reference record. Safe to call repeatedly.
+func clear() -> void:
+	_reference_keys_by_placement_key.clear()
+
+
+## Returns the number of currently referenced placement keys.
+func active_count() -> int:
+	return _reference_keys_by_placement_key.size()
+
+
+## Returns detached, placement/reference-key-sorted diagnostic records.
+func diagnostic_snapshot() -> Array[Dictionary]:
+	var placement_keys: Array = _reference_keys_by_placement_key.keys()
+	placement_keys.sort()
+	var snapshot: Array[Dictionary] = []
+	for placement_key_variant in placement_keys:
+		var placement_key := String(placement_key_variant)
+		var reference_keys: Array = (
+			_reference_keys_by_placement_key[placement_key] as Dictionary
+		).keys()
+		reference_keys.sort()
+		snapshot.append({
+			"placement_key": placement_key,
+			"reference_keys": reference_keys.duplicate(),
+		})
+	return snapshot

src/render/wmo/wmo_placement_registry.gd.uid

@@ -0,0 +1 @@
+uid://cfbo5fw33vw4f