Charge more for each berth, and show the bill

#220: every berth past the first paid one costs 1.12x the one before it, on
top of the flat per-vessel charge. A linear bill makes the tenth hull no more
of a decision than the second; compounding weighs each addition against the
whole fleet behind it. Shallow on purpose - the thirteenth berth costs about
three and a half times the second, the twentieth about seven and a half.

Fleet Offices gain a menu naming the whole bill per minute, a line per paying
berth with its multiplier, and the arithmetic in words. It renders
fleet_upkeep_breakdown(), which is the calculation the charging loop itself
runs: a readout that summed independently could quote a bill the game does
not take, which is the thing worth preventing here. The test pins that what
the menu quotes for a berth is what that office is charged.

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

buildings/FleetOfficeBuildingVisual.tscn

@@ -8,4 +8,4 @@ script = ExtResource("1")
 
 [node name="ActionProvider" type="Node" parent="."]
 script = ExtResource("2")
-actions = PackedStringArray("transfer")
+actions = PackedStringArray("upkeep", "transfer")

controllers/BuildController.gd

@@ -34,6 +34,8 @@ const HUD_ROW_GAP := 16.0
 @onready var garrison_menu: Control = get_node("../UI/GarrisonMenu")
 # #216: where a hub or a workshop is told how many craft to keep.
 @onready var station_menu: Control = get_node("../UI/StationMenu")
+# #220: what the fleet costs to keep, and the arithmetic behind it.
+@onready var upkeep_menu: Control = get_node("../UI/FleetUpkeepMenu")
 @onready var scanner_menu: Control = get_node("../UI/ScannerMenu")
 
 var pending_build_type: String = ""
@@ -114,7 +116,7 @@ func _seat_hud_columns() -> void:
 func _menu_is_open() -> bool:
 	for menu in [build_menu, craft_menu, lab_menu, transfer_menu, hangar_menu,
 			formation_menu, skill_menu, planning_menu, garrison_menu, scanner_menu,
-			station_menu]:
+			station_menu, upkeep_menu]:
 		if menu.visible:
 			return true
 	return false
@@ -319,6 +321,8 @@ func _on_action_pressed() -> void:
 		scanner_menu.open_menu()
 	elif building_action == "staff":
 		station_menu.open_for(building_id)
+	elif building_action == "upkeep":
+		upkeep_menu.open_for(building_id)
 
 
 func _on_scan_requested(definition_id: String) -> void:
@@ -797,6 +801,7 @@ func _layout_hangar() -> void:
 func _refresh_garrison() -> void:
 	garrison_menu.refresh()
 	station_menu.refresh()
+	upkeep_menu.refresh()
 
 
 func _refresh_planning() -> void:

core/GameState.gd

@@ -776,6 +776,16 @@ signal fleet_upkeep_failed(slot_index: int, vessel_type: String)
 # ticket asks for and needs no second table to fall out of step with.
 const FLEET_OFFICE_UPKEEP_SECONDS: float = 25.0
 const FLEET_OFFICE_UPKEEP_DIVISOR: int = 8
+# #220: and each berth costs more than the one before it. A flat per-vessel
+# charge means a big fleet is only linearly harder to keep, so the tenth hull
+# is no more of a decision than the second; compounding makes every addition
+# weigh against the whole fleet behind it.
+#
+# Deliberately shallow - the ticket asks for a slow one. At 1.12 the thirteenth
+# berth costs about three and a half times the second, and the twentieth about
+# seven and a half. A steeper rate reaches "unaffordable" while the player is
+# still learning what the fleet is for.
+const FLEET_UPKEEP_GROWTH: float = 1.12
 
 
 # Offices in the order they were built, which is the order they are matched to
@@ -800,16 +810,62 @@ func supplied_fleet_office_count() -> int:
 # What one berth costs per charge, for the vessel actually sitting in it. An
 # empty answer means this vessel is free to keep - which is true of nothing
 # the crafter builds, and is what an unknown type falls back to.
-func fleet_office_upkeep(vessel_type: String) -> Dictionary:
+# What one berth costs per charge. `slot_index` is the fleet position it
+# keeps, so the first berth past the free one pays the base rate and every
+# berth after it pays the compounded one (#220).
+func fleet_office_upkeep(vessel_type: String, slot_index: int = BASE_FLEET_SIZE) -> Dictionary:
 	var upkeep: Dictionary = {}
+	var scale: float = fleet_upkeep_scale(slot_index)
 	for resource_type in product_costs(vessel_type):
 		var share: int = int(ceil(float(product_costs(vessel_type)[resource_type])
-			/ float(FLEET_OFFICE_UPKEEP_DIVISOR)))
+			/ float(FLEET_OFFICE_UPKEEP_DIVISOR) * scale))
 		if share > 0:
 			upkeep[resource_type] = share
 	return upkeep
 
 
+# The multiplier on a berth at this fleet position. The free hull and the
+# first paid berth both sit at 1.0, so the curve starts where the charging
+# starts rather than partway up it.
+func fleet_upkeep_scale(slot_index: int) -> float:
+	return pow(FLEET_UPKEEP_GROWTH, maxi(slot_index - BASE_FLEET_SIZE, 0))
+
+
+# The whole bill, berth by berth, for the readout #220 asks for: what each
+# one is keeping, what it is charged, and what that is per minute. Computed
+# here rather than in the menu so the numbers shown are the numbers charged -
+# a readout that recomputes them separately can disagree with the loop that
+# actually takes the resources.
+func fleet_upkeep_breakdown() -> Dictionary:
+	var berths: Array = []
+	var per_minute: Dictionary = {}
+	var charges_per_minute: float = 60.0 / FLEET_OFFICE_UPKEEP_SECONDS
+	var offices: Array = fleet_offices()
+	for i in range(offices.size()):
+		var slot_index: int = i + BASE_FLEET_SIZE
+		var vessel_type: String = fleet_office_vessel(slot_index)
+		if vessel_type == "":
+			continue  # a berth standing empty is charged nothing
+		var costs: Dictionary = fleet_office_upkeep(vessel_type, slot_index)
+		berths.append({
+			"slot": slot_index + 1,
+			"vessel_type": vessel_type,
+			"scale": fleet_upkeep_scale(slot_index),
+			"costs": costs,
+			"starved": bool(offices[i].get("starved", false)),
+		})
+		for resource_type in costs:
+			per_minute[resource_type] = float(per_minute.get(resource_type, 0.0)) \
+				+ float(costs[resource_type]) * charges_per_minute
+	return {
+		"berths": berths,
+		"per_minute": per_minute,
+		"charge_seconds": FLEET_OFFICE_UPKEEP_SECONDS,
+		"divisor": FLEET_OFFICE_UPKEEP_DIVISOR,
+		"growth": FLEET_UPKEEP_GROWTH,
+	}
+
+
 # The vessel an office is answerable for, or "" when the fleet is smaller than
 # the berths built for it - an office with nothing in it costs nothing.
 func fleet_office_vessel(slot_index: int) -> String:
@@ -841,7 +897,8 @@ func _advance_fleet_office_upkeep(delta: float) -> void:
 			office.upkeep_progress = progress
 			continue
 		office.upkeep_progress = progress - FLEET_OFFICE_UPKEEP_SECONDS
-		var upkeep: Dictionary = fleet_office_upkeep(vessel_type)
+		var upkeep: Dictionary = fleet_office_upkeep(vessel_type,
+			i + BASE_FLEET_SIZE)
 		var inventory: RefCounted = _inventory_for_record(office)
 		var affordable: bool = true
 		for resource_type in upkeep:

tests/_fleet_upkeep_preview.gd

@@ -0,0 +1,34 @@
+extends Node2D
+
+# Preview, not a test - #220's upkeep readout with a fleet worth reading:
+# several berths of different hulls, so the per-berth lines, the compounding
+# multiplier and the per-minute total all have something to show.
+#
+#   bash tests/screenshot.sh res://tests/_fleet_upkeep_preview.tscn shots/fleet_upkeep.png 3 720x1280
+
+
+func _ready() -> void:
+	GameState.buildings.clear()
+	GameState.extractors.clear()
+	GameState.transporters.clear()
+	GameState.reset_progression()
+	GameState.intro_active = false
+	GameState.add_building(GameState.BUILDING_MOTHERSHIP, Vector2.ZERO)
+	var office_ids: Array = []
+	for i in range(5):
+		office_ids.append(GameState.add_building(GameState.BUILDING_FLEET_OFFICE,
+			Vector2(400.0 * float(i + 1), 300.0)))
+	var main: Node = load("res://world/Main.tscn").instantiate()
+	add_child(main)
+	main.get_node("AsteroidField").set_process(false)
+	main.get_node("EnemySpawner").set_process(false)
+	# Spawned for real rather than by writing fleet_vessel_types directly: the
+	# Fleet rewrites that from what is actually flying the moment it composes
+	# itself, so a value set beforehand is discarded.
+	main.get_node("Fleet").spawn_ships(6, Vector2.ZERO, PackedStringArray([
+		GameState.VESSEL_INTERCEPTOR, GameState.VESSEL_LASER,
+		GameState.VESSEL_GAS_BOMBER, GameState.VESSEL_DISTORDER,
+		GameState.VESSEL_LASER, GameState.VESSEL_SHIELD]))
+	# One office left unsupplied, so the unpaid marker is visible too.
+	GameState.find_building(int(office_ids[3])).starved = true
+	main.get_node("UI/FleetUpkeepMenu").open_for(int(office_ids[0]))

tests/_fleet_upkeep_preview.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://tests/_fleet_upkeep_preview.gd" id="1"]
+
+[node name="FleetUpkeepPreview" type="Node2D"]
+script = ExtResource("1")

tests/test_fleet_upkeep_scaling.gd

@@ -0,0 +1,111 @@
+extends SceneTree
+
+# Forgejo #220: the fleet costs more per hull as it grows, and the Fleet
+# Office says so with the arithmetic shown.
+#
+# The interesting failure is not "the sum is wrong" - it is the readout and
+# the charging loop drifting apart, so the menu quotes a bill the game does
+# not take. So what is checked is that the SAME numbers come out of both.
+#
+# Covers:
+#   A. the first paid berth pays the base rate, undialled
+#   B. each berth past it pays more than the one before, compounding
+#   C. the growth is slow - a mid-sized fleet is dearer, not ruinous
+#   D. the breakdown's per-minute total matches its own per-berth charges
+#   E. and the charges it quotes are the ones actually withdrawn
+#   F. an empty berth is quoted nothing
+
+var state: Node
+
+
+func _initialize() -> void:
+	state = root.get_node("GameState")
+	state.buildings.clear()
+	state.transporters.clear()
+	state.reset_progression()
+	state.reset_new_game()
+	state.intro_active = false
+	state.fleet_vessel_types = PackedStringArray()
+
+
+func _process(_delta: float) -> bool:
+	var vessel: String = GameState.VESSEL_LASER
+	var base: Dictionary = state.fleet_office_upkeep(vessel, GameState.BASE_FLEET_SIZE)
+	if base.is_empty():
+		return _fail("a laser berth is charged nothing at all")
+
+	# --- A. the first paid berth is the base rate -------------------
+	if not is_equal_approx(state.fleet_upkeep_scale(GameState.BASE_FLEET_SIZE), 1.0):
+		return _fail("the first paid berth is already dialled up (x%.2f)" \
+			% state.fleet_upkeep_scale(GameState.BASE_FLEET_SIZE))
+
+	# --- B. and every berth after it costs more ---------------------
+	var previous: float = 0.0
+	for slot in range(GameState.BASE_FLEET_SIZE, GameState.BASE_FLEET_SIZE + 12):
+		var scale: float = state.fleet_upkeep_scale(slot)
+		if scale < previous:
+			return _fail("berth %d is cheaper than the one before it" % (slot + 1))
+		previous = scale
+	var twelfth: float = state.fleet_upkeep_scale(GameState.BASE_FLEET_SIZE + 11)
+	if twelfth <= 1.0:
+		return _fail("twelve berths in, upkeep has not risen at all")
+
+	# --- C. slowly, though ------------------------------------------
+	if twelfth > 6.0:
+		return _fail("the twelfth berth costs x%.1f - that is not a slow exponential" % twelfth)
+	print("berth scaling: 1.00 at the first paid berth, x%.2f twelve in" % twelfth)
+
+	# --- D/E/F. the quoted bill IS the charged one ------------------
+	# Three offices, two of them crewed: the third berth stands empty and
+	# must be quoted nothing.
+	var office_ids: Array = []
+	for i in range(3):
+		office_ids.append(state.add_building(GameState.BUILDING_FLEET_OFFICE,
+			Vector2(500.0 * float(i + 1), 0.0)))
+	state.fleet_vessel_types = PackedStringArray([
+		GameState.VESSEL_INTERCEPTOR, vessel, vessel])
+
+	var breakdown: Dictionary = state.fleet_upkeep_breakdown()
+	var berths: Array = breakdown.berths
+	if berths.size() != 2:
+		return _fail("%d berths quoted for a fleet of 3 with 3 offices, expected 2 paying" \
+			% berths.size())
+	if int(berths[1].costs.get(GameState.RESOURCE_ORE, 0)) \
+			<= int(berths[0].costs.get(GameState.RESOURCE_ORE, 0)) - 1:
+		return _fail("the second paid berth is quoted less than the first")
+
+	# The per-minute figure has to be the per-berth charges, at the rate they
+	# are actually taken - not a separate estimate.
+	var charges: float = 60.0 / float(breakdown.charge_seconds)
+	for resource_type in breakdown.per_minute:
+		var summed: float = 0.0
+		for berth in berths:
+			summed += float(berth.costs.get(resource_type, 0)) * charges
+		if not is_equal_approx(float(breakdown.per_minute[resource_type]), summed):
+			return _fail("%s quoted at %.2f/min, its own berths add to %.2f" % [
+				resource_type, float(breakdown.per_minute[resource_type]), summed])
+	print("bill: %s, from %d paying berths" % [breakdown.per_minute, berths.size()])
+
+	# And a charge actually taken matches what was quoted for that berth.
+	var quoted: int = int(berths[0].costs.get(GameState.RESOURCE_ORE, 0))
+	var office: Dictionary = state.find_building(int(office_ids[0]))
+	var store: RefCounted = state.building_inventory(int(office_ids[0]))
+	store.set_amount(GameState.RESOURCE_ORE, 500)
+	store.set_amount(GameState.RESOURCE_ENERGY, 500)
+	var before: int = store.amount(GameState.RESOURCE_ORE)
+	office.upkeep_progress = GameState.FLEET_OFFICE_UPKEEP_SECONDS
+	state._advance_fleet_office_upkeep(0.1)
+	var taken: int = before - store.amount(GameState.RESOURCE_ORE)
+	if taken != quoted:
+		return _fail("berth 2 was quoted %d ore and charged %d" % [quoted, taken])
+	print("what the menu quotes for a berth is what the office pays: %d ore" % taken)
+
+	print("TEST_FLEET_UPKEEP_SCALING: PASS")
+	quit(0)
+	return true
+
+
+func _fail(message: String) -> bool:
+	print("TEST_FLEET_UPKEEP_SCALING: FAIL (%s)" % message)
+	quit(1)
+	return true

ui/menus/FleetUpkeepMenu.gd

@@ -0,0 +1,71 @@
+extends "res://ui/menus/ModalMenu.gd"
+
+# Forgejo #220: what the fleet costs to keep, and WHY it costs that.
+#
+# A Fleet Office charges for the vessel in its berth every 25 seconds, and
+# each berth costs more than the one before it. Neither of those is visible
+# from the resource bar - the player watches a number fall and cannot tell
+# which of their own decisions is draining it - so this states the bill and
+# shows the arithmetic that produced it, line by line.
+#
+# Every number here comes from GameState.fleet_upkeep_breakdown(), which is
+# the same calculation the charging loop runs. A readout that did its own sum
+# could disagree with what is actually being taken, which is exactly the kind
+# of "the game is lying to me" the ticket is about.
+
+@onready var total_label: Label = $TotalLabel
+@onready var detail_label: Label = $DetailLabel
+@onready var formula_label: Label = $FormulaLabel
+
+var building_id: int = 0
+
+
+func open_for(next_building_id: int) -> void:
+	building_id = next_building_id
+	open_menu()
+	refresh()
+
+
+func close_menu() -> void:
+	super.close_menu()
+	building_id = 0
+
+
+func refresh() -> void:
+	if not visible:
+		return
+	var breakdown: Dictionary = GameState.fleet_upkeep_breakdown()
+	var berths: Array = breakdown.berths
+	var per_minute: Dictionary = breakdown.per_minute
+
+	if per_minute.is_empty():
+		total_label.text = "NOTHING TO KEEP"
+	else:
+		var parts: PackedStringArray = PackedStringArray()
+		for resource_type in per_minute:
+			parts.append("%.1f %s" % [float(per_minute[resource_type]),
+				GameState.resource_name(String(resource_type)).to_lower()])
+		total_label.text = "%s PER MINUTE" % " · ".join(parts)
+
+	# One line per paying berth: which hull, what it is charged, and the
+	# multiplier that got it there. An empty berth is charged nothing and is
+	# left out rather than listed at zero.
+	var lines: PackedStringArray = PackedStringArray()
+	for berth in berths:
+		var costs: PackedStringArray = PackedStringArray()
+		for resource_type in berth.costs:
+			costs.append("%d %s" % [int(berth.costs[resource_type]),
+				GameState.resource_name(String(resource_type)).to_lower()])
+		lines.append("BERTH %d  %-16s %s  (x%.2f)%s" % [
+			int(berth.slot), GameState.vessel_name(String(berth.vessel_type)),
+			" ".join(costs), float(berth.scale),
+			"  — UNPAID" if bool(berth.starved) else "",
+		])
+	detail_label.text = "\n".join(lines) if not lines.is_empty() \
+		else "No berth is being charged. Build a Fleet Office and put a vessel in it."
+
+	formula_label.text = ("Each berth is charged every %ds: the vessel's build price "
+		+ "divided by %d, then multiplied by %.2f for every berth past the first "
+		+ "paid one. The first vessel is free.") % [
+			int(breakdown.charge_seconds), int(breakdown.divisor),
+			float(breakdown.growth)]

ui/menus/FleetUpkeepMenu.tscn

@@ -0,0 +1,77 @@
+[gd_scene load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://ui/IconButton.gd" id="icon"]
+[ext_resource type="Script" path="res://ui/menus/FleetUpkeepMenu.gd" id="menu"]
+
+[node name="FleetUpkeepMenu" type="Control" groups=["modal_menus"]]
+visible = false
+mouse_filter = 2
+anchor_right = 1.0
+anchor_bottom = 1.0
+script = ExtResource("menu")
+
+[node name="Backdrop" type="ColorRect" parent="."]
+mouse_filter = 2
+anchor_right = 1.0
+anchor_bottom = 1.0
+color = Color(0.03, 0.03, 0.08, 0.96)
+
+[node name="TitleLabel" type="Label" parent="."]
+mouse_filter = 2
+anchor_right = 1.0
+offset_left = 24.0
+offset_top = 24.0
+offset_right = -180.0
+offset_bottom = 100.0
+theme_override_font_sizes/font_size = 40
+text = "FLEET UPKEEP"
+horizontal_alignment = 1
+
+[node name="CloseButton" type="Control" parent="."]
+anchor_left = 1.0
+anchor_right = 1.0
+offset_left = -140.0
+offset_top = 24.0
+offset_right = -24.0
+offset_bottom = 140.0
+script = ExtResource("icon")
+icon = 1
+glow_color = Color(0.55, 0.6, 1, 1)
+
+[node name="TotalLabel" type="Label" parent="."]
+mouse_filter = 2
+anchor_right = 1.0
+offset_left = 32.0
+offset_top = 150.0
+offset_right = -32.0
+offset_bottom = 220.0
+theme_override_font_sizes/font_size = 32
+theme_override_colors/font_color = Color(1, 0.85, 0.35, 1)
+text = ""
+horizontal_alignment = 1
+
+[node name="DetailLabel" type="Label" parent="."]
+mouse_filter = 2
+anchor_right = 1.0
+offset_left = 32.0
+offset_top = 250.0
+offset_right = -32.0
+offset_bottom = 860.0
+theme_override_font_sizes/font_size = 30
+theme_override_colors/font_color = Color(0.72, 0.88, 0.96, 1)
+text = ""
+autowrap_mode = 2
+
+[node name="FormulaLabel" type="Label" parent="."]
+mouse_filter = 2
+anchor_right = 1.0
+offset_left = 40.0
+offset_top = 880.0
+offset_right = -40.0
+offset_bottom = 1060.0
+theme_override_font_sizes/font_size = 26
+theme_override_colors/font_color = Color(0.55, 0.78, 0.86, 1)
+text = ""
+horizontal_alignment = 1
+vertical_alignment = 1
+autowrap_mode = 2

world/Main.tscn

@@ -11,6 +11,7 @@
 [ext_resource type="PackedScene" path="res://ui/menus/DevMenu.tscn" id="menu_dev"]
 [ext_resource type="PackedScene" path="res://ui/menus/ScannerMenu.tscn" id="menu_scanner"]
 [ext_resource type="PackedScene" path="res://ui/menus/StationMenu.tscn" id="menu_station"]
+[ext_resource type="PackedScene" path="res://ui/menus/FleetUpkeepMenu.tscn" id="menu_upkeep"]
 [ext_resource type="PackedScene" path="res://ui/ScannerGuidance.tscn" id="scanner_guidance"]
 
 
@@ -530,6 +531,8 @@ icon = 1
 [node name="ScannerMenu" parent="UI" instance=ExtResource("menu_scanner")]
 
 [node name="StationMenu" parent="UI" instance=ExtResource("menu_station")]
+
+[node name="FleetUpkeepMenu" parent="UI" instance=ExtResource("menu_upkeep")]
 [node name="QuestPanel" type="Control" parent="UI" groups=["modal_menus"]]
 visible = false
 mouse_filter = 2