Refactor code structure for improved readability and maintainability

scripts/editors/stage/stage_run_session.gd

@@ -4,6 +4,7 @@ extends RefCounted
 
 const STICKMAN_RIG_SCRIPT := preload("res://scripts/characters/stickman/stickman_rig.gd")
 const PROP_STAGE_ROLES := preload("res://scripts/props/prop_stage_roles.gd")
+const STAGE_SCENERY_ARTWORK := preload("res://scripts/stage/scenery/stage_scenery_artwork.gd")
 
 const STATE_STOPPED: int = 0
 const STATE_RUNNING: int = 1
@@ -224,6 +225,12 @@ func capture_prop_pause_state(body: RigidBody2D) -> Dictionary:
 
 
 func save_object_state(node: Node2D) -> void:
+	# Scenery artwork is editor-authored and does not move during simulation.
+	# Its live transform is the document state, so a pre-PLAY snapshot must not
+	# restore an old position when the user returns to EDIT.
+	if node is STAGE_SCENERY_ARTWORK:
+		authored_state.erase(node.get_instance_id())
+		return
 	var authored_rotation: float = node.global_rotation
 	if node is STICKMAN_RIG_SCRIPT and (node as StickmanRig).get_facing_profile() == StickmanRig.FacingProfile.LEFT:
 		# LEFT is a derived root reflection. Remove it before persisting the
@@ -256,6 +263,9 @@ func restore_authored_state(stage_mode_name: String, run_state_name: String, cam
 		if node == null or not is_instance_valid(node):
 			authored_state.erase(id)
 			continue
+		if node is STAGE_SCENERY_ARTWORK:
+			authored_state.erase(id)
+			continue
 		node.global_position = entry.get("position", node.global_position)
 		node.global_rotation = entry.get("rotation", node.global_rotation)
 		if entry.has("scale"):