render: extract WMO scene resource finalizer

src/render/wmo/wmo_scene_resource_finalizer.gd

@@ -0,0 +1,97 @@
+class_name WmoSceneResourceFinalizer
+extends RefCounted
+
+## Polls cached WMO PackedScene requests and publishes validated outcomes.
+## File-size admission, live fallback and attached Node lifetime remain caller-owned.
+
+var _scene_cache_validator: Object
+var _resource_loader_adapter: Object
+
+
+func _init(
+	scene_cache_validator: Object,
+	resource_loader_adapter: Object = null
+) -> void:
+	_scene_cache_validator = scene_cache_validator
+	_resource_loader_adapter = resource_loader_adapter
+
+
+## Polls a detached pending snapshot in insertion order. Terminal requests are
+## published as the exact validated PackedScene or the historical missing state.
+func poll_terminal_requests(scene_resource_cache_state: RefCounted) -> int:
+	if scene_resource_cache_state == null:
+		return 0
+	var completed_request_count := 0
+	var request_paths: Dictionary = scene_resource_cache_state.call(
+		"request_paths_snapshot"
+	)
+	for normalized_relative_path_variant in request_paths.keys():
+		var normalized_relative_path := String(normalized_relative_path_variant)
+		var resource_path := String(request_paths[normalized_relative_path_variant])
+		var load_status := load_threaded_get_status(resource_path)
+		if (
+			load_status != ResourceLoader.THREAD_LOAD_LOADED
+			and load_status != ResourceLoader.THREAD_LOAD_FAILED
+		):
+			continue
+		if load_status != ResourceLoader.THREAD_LOAD_LOADED:
+			scene_resource_cache_state.call(
+				"complete_request_as_missing",
+				normalized_relative_path
+			)
+			completed_request_count += 1
+			continue
+		var loaded_resource := load_threaded_get(resource_path)
+		var loaded_scene := loaded_resource as PackedScene
+		if is_scene_cache_current(loaded_scene):
+			scene_resource_cache_state.call(
+				"complete_request_with_scene",
+				normalized_relative_path,
+				loaded_scene
+			)
+		else:
+			scene_resource_cache_state.call(
+				"complete_request_as_missing",
+				normalized_relative_path
+			)
+		completed_request_count += 1
+	return completed_request_count
+
+
+## Instantiates one Node3D probe, delegates the existing WMOBuilder metadata
+## check and synchronously releases the probe before returning.
+func is_scene_cache_current(scene: PackedScene) -> bool:
+	if scene == null or _scene_cache_validator == null:
+		return false
+	var instantiated_node := scene.instantiate()
+	if not (instantiated_node is Node3D):
+		if instantiated_node != null:
+			instantiated_node.free()
+		return false
+	var instance := instantiated_node as Node3D
+	var is_current := bool(_scene_cache_validator.call(
+		"is_scene_cache_current",
+		instance
+	))
+	instance.free()
+	return is_current
+
+
+## Production ResourceLoader status boundary; injectable for synthetic tests.
+func load_threaded_get_status(resource_path: String) -> int:
+	if _resource_loader_adapter != null:
+		return int(_resource_loader_adapter.call(
+			"load_threaded_get_status",
+			resource_path
+		))
+	return ResourceLoader.load_threaded_get_status(resource_path)
+
+
+## Production ResourceLoader result boundary; injectable for synthetic tests.
+func load_threaded_get(resource_path: String) -> Resource:
+	if _resource_loader_adapter != null:
+		return _resource_loader_adapter.call(
+			"load_threaded_get",
+			resource_path
+		) as Resource
+	return ResourceLoader.load_threaded_get(resource_path)