Add a free-costs sandbox tool

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019AJMdB7iuHuLFZM1aBu3GD

core/GameState.gd

@@ -190,11 +190,17 @@ var research_points: int = 0
 # place to set it - assigning dev_mode anywhere, tests included, reaches
 # world generation.
 var dev_unlimited_resources: bool = false
+# #202: every research and production price answers zero while this is on.
+# A separate switch from the one above rather than a stronger version of it -
+# unlimited resources tests whether a price can be PAID, and this tests what
+# happens when there is no price at all, which is a different play-test.
+var dev_free_costs: bool = false
 var dev_mode: bool = false:
 	set(value):
 		dev_mode = value
 		if not value:
 			dev_unlimited_resources = false
+			dev_free_costs = false
 		WORLD_GEN.dev_planets_enabled = value
 
 # Explored-chunk history for the world map's fog-of-war reveal. Lives
@@ -676,7 +682,7 @@ func prerequisite_met(id: String) -> bool:
 # ever compared two nodes by price - keeps working on a plain number.
 func skill_costs(id: String) -> Dictionary:
 	var node: Dictionary = skill_node(id)
-	if node.is_empty():
+	if node.is_empty() or costs_are_free():
 		return {}
 	var costs: Dictionary = node.get("costs", {})
 	if not costs.is_empty():
@@ -692,7 +698,7 @@ func can_unlock(id: String, payment_position: Variant = null) -> bool:
 
 
 func skill_research_point_cost(id: String) -> int:
-	return int(skill_node(id).get("research_points", 0))
+	return 0 if costs_are_free() else int(skill_node(id).get("research_points", 0))
 
 
 func unlock(id: String, payment_position: Variant = null) -> bool:
@@ -792,6 +798,7 @@ func reset_new_game() -> void:
 	boost_depleted_notice = false
 	research_points = 0
 	dev_unlimited_resources = false
+	dev_free_costs = false
 	dev_mode = false
 	explored_chunks.clear()
 	scanner_target.clear()
@@ -954,6 +961,21 @@ func set_dev_unlimited_resources(enabled: bool) -> bool:
 	return true
 
 
+func set_dev_free_costs(enabled: bool) -> bool:
+	if enabled and not dev_mode:
+		return false
+	dev_free_costs = enabled
+	return true
+
+
+# Asked by every price below, and by the menus that display them. The dev_mode
+# term is not redundant: the setter refuses outside a dev game and the dev_mode
+# setter clears the flag, so this is the third guard rather than the first, and
+# it is the one that holds if a save or a test sets the field directly.
+func costs_are_free() -> bool:
+	return dev_mode and dev_free_costs
+
+
 func _refill_dev_resources() -> void:
 	for resource_type in resource_types():
 		if bank_inventory.amount(resource_type) < DEV_UNLIMITED_AMOUNT:
@@ -1052,7 +1074,7 @@ func find_building(id: int) -> Dictionary:
 # there is one question with one answer whatever is being bought.
 func building_costs(type: String) -> Dictionary:
 	var definition: Resource = building_definition(type)
-	if definition == null:
+	if definition == null or costs_are_free():
 		return {}
 	if not definition.build_resource_costs.is_empty():
 		return definition.build_resource_costs.duplicate()
@@ -1494,7 +1516,10 @@ func unlock_vessel(vessel: String, payment_position: Variant = null) -> bool:
 	if definition == null or definition.unlock_id == "" or vessel_is_unlocked(vessel) or not has_ship_lab():
 		return false
 	var costs: Dictionary = research_costs(definition.unlock_id)
-	var points_needed: int = int(definition.research_point_cost)
+	# Through the accessor, not off the definition: this used to be the one
+	# place a research price was read straight from its file, which #202's
+	# free-costs switch would have left charging full price here alone.
+	var points_needed: int = research_point_cost(definition.unlock_id)
 	if research_points < points_needed or not spend_resources(costs, payment_position):
 		return false
 	if points_needed > 0:
@@ -1540,7 +1565,7 @@ func upgrade_maxed(id: String) -> bool:
 
 func upgrade_cost(id: String) -> int:
 	var d: Dictionary = upgrade_def(id)
-	if d.is_empty():
+	if d.is_empty() or costs_are_free():
 		return 0
 	return int(d.cost) * (upgrade_level(id) + 1)
 
@@ -1631,7 +1656,7 @@ func product_cost(product: String) -> int:
 
 func product_costs(product: String) -> Dictionary:
 	var definition: Resource = vessel_definition(product)
-	if definition == null:
+	if definition == null or costs_are_free():
 		return {}
 	if not definition.build_resource_costs.is_empty():
 		return definition.build_resource_costs.duplicate()
@@ -2332,6 +2357,8 @@ func research_cost(id: String) -> int:
 
 
 func research_point_cost(id: String) -> int:
+	if costs_are_free():
+		return 0
 	var unlock_definition: Resource = vessel_for_unlock(id)
 	if unlock_definition != null:
 		return int(unlock_definition.research_point_cost)
@@ -2340,6 +2367,8 @@ func research_point_cost(id: String) -> int:
 
 
 func research_costs(id: String) -> Dictionary:
+	if costs_are_free():
+		return {}
 	var unlock_definition: Resource = vessel_for_unlock(id)
 	if unlock_definition != null:
 		if not unlock_definition.unlock_resource_costs.is_empty():