Preserve packed definition arrays in exports

buildings/BuildingActionProvider.gd

@@ -1,3 +1,5 @@
 extends Node
 
-@export var actions: PackedStringArray = []
+# Explicit empty PackedStringArray defaults are not export-safe for custom
+# scripted objects in Godot 4.7.1.
+@export var actions: PackedStringArray

buildings/BuildingDefinition.gd

@@ -18,7 +18,9 @@ extends Resource
 @export var action_icon: int
 @export var menu_icon: int
 @export var visual_scene: PackedScene
-@export var capabilities: PackedStringArray = []
+# No explicit empty default: Godot 4.7.1 can lose the value when exporting a
+# custom resource to binary .res.
+@export var capabilities: PackedStringArray
 @export var logistics: Resource
 @export var map_color: Color = Color.WHITE
 @export var map_sides: int = 4

buildings/BuildingLogisticsProfile.gd

@@ -6,7 +6,9 @@ extends Resource
 # converter does not require another resource-type branch in transport code.
 
 @export var input_buffers: Dictionary = {}
-@export var collected_outputs: PackedStringArray = []
+# See BuildingDefinition.capabilities: an explicit empty packed-array default
+# is not export-safe in Godot 4.7.1 custom resources.
+@export var collected_outputs: PackedStringArray
 @export var conversion_input: String = ""
 @export var conversion_output: String = ""
 @export var conversion_rate: float = 0.0