Transporter vessels, an explicit store button, and bottom-anchored menus

Forgejo #19, part 6 of #12. Transporters are built at the ship crafter,
fly themselves to the nearest hub and wait there. When a building is
short of what its queue needs, the nearest idle transporter runs
hub -> mothership -> building -> hub. Ore leaves the bank when it is
loaded and lands in the building's stock on arrival, so what is drawn
and what happens are the same event - the extractor hauler's rule.

Production orders are now TYPED (interceptor / transporter) rather than
a bare count, since the crafter builds two different things. One at a
time is dispatched per building: without that, every idle transporter
chases the same shortfall and they all arrive carrying ore nobody needs.

Three fixes from play-testing feedback:

- Storing ore into a building is now a deliberate button press, not a
  side effect of opening the menu.
- The mothership's load-ore controls were positioned from the TOP of the
  screen, so on any viewport shorter than ~1300px the label fell off the
  bottom. They are anchored to the bottom edge now, and the label had no
  explicit font size so it inherited the theme's 78px and wrapped off
  screen. Checked at 720x960 and 720x1280.
- The craft button looked live and did nothing. It was not the transport
  work: BASE_FLEET_SIZE is 5 and a new game starts with exactly 5 ships,
  so the fleet is at its cap from the first frame and every interceptor
  order was refused. The button is now visibly disabled and says why.
  The underlying balance (crafter useless until Wing Doctrine) is left
  alone - that is a design call, not a bug to quietly change.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

BuildController.gd

@@ -38,6 +38,9 @@ extends Node2D
 
 @onready var craft_menu: Control = get_node("../UI/CraftMenu")
 @onready var craft_interceptor_button: IconButton = get_node("../UI/CraftMenu/InterceptorButton")
+@onready var craft_transporter_button: IconButton = get_node("../UI/CraftMenu/TransporterButton")
+@onready var craft_store_button: IconButton = get_node("../UI/CraftMenu/StoreOreButton")
+@onready var craft_store_label: Label = get_node("../UI/CraftMenu/StoreOreLabel")
 @onready var craft_close_button: IconButton = get_node("../UI/CraftMenu/CloseButton")
 @onready var craft_status: Label = get_node("../UI/CraftMenu/StatusLabel")
 @onready var load_ore_button: IconButton = get_node("../UI/SkillMenu/LoadOreButton")
@@ -113,6 +116,8 @@ func _ready() -> void:
 
 	craft_interceptor_button.pressed.connect(_on_craft_interceptor)
 	load_ore_button.pressed.connect(_on_load_ore)
+	craft_transporter_button.pressed.connect(_on_craft_transporter)
+	craft_store_button.pressed.connect(_on_store_ore)
 	craft_close_button.pressed.connect(func(): craft_menu.visible = false)
 
 	formation_close_button.pressed.connect(func(): formation_menu.visible = false)
@@ -452,9 +457,33 @@ func _refresh_craft_status() -> void:
 	var queued: int = GameState.pending_orders(craft_building_id)
 	var stock: int = GameState.building_stock(craft_building_id)
 	var queue_text: String = "" if queued == 0 else "      Queued %d" % queued
-	craft_status.text = "Interceptor  %d ore      Here %d%s      Fleet %d/%d" % [
-		GameState.SHIP_COST, stock, queue_text,
-		fleet.ships.size(), GameState.max_fleet_size()
+	craft_status.text = "Interceptor %d   Transporter %d      Here %d%s" % [
+		GameState.SHIP_COST, GameState.TRANSPORTER_COST, stock, queue_text
+	]
+	# Nowhere to station one means the order would be refused, so say so
+	# rather than letting the button look available and do nothing.
+	craft_transporter_button.enabled = GameState.has_transport_hub()
+	craft_transporter_button.queue_redraw()
+
+	craft_store_label.text = "Store ore here\nHold %d" % GameState.fleet_cargo
+	craft_store_button.enabled = GameState.fleet_cargo > 0
+	craft_store_button.queue_redraw()
+
+	# A full fleet cannot take another vessel, so the order would be refused.
+	# Showing that on the button is the difference between "not available yet"
+	# and a button that looks live and silently does nothing when pressed.
+	var room: bool = fleet.ships.size() + GameState.ships_owed \
+		+ GameState.pending_orders_of(craft_building_id, GameState.PRODUCT_SHIP) \
+		< GameState.max_fleet_size()
+	craft_interceptor_button.enabled = room
+	craft_interceptor_button.queue_redraw()
+	# One statement of the fleet count, either way round: the capacity line
+	# replaces the plain readout rather than being bolted in front of it.
+	if room:
+		craft_status.text += "      Fleet %d/%d" % [fleet.ships.size(), GameState.max_fleet_size()]
+	else:
+		craft_status.text = "Fleet full %d/%d - research capacity at the mothership\n%s" % [
+			fleet.ships.size(), GameState.max_fleet_size(), craft_status.text
 		]
 
 
@@ -463,7 +492,8 @@ func _on_craft_interceptor() -> void:
 		return
 	# Still refused when there is nowhere to put the vessel - queueing an
 	# order that can never be delivered would just bank ships_owed forever.
-	if fleet.ships.size() + GameState.ships_owed + GameState.pending_orders(craft_building_id) \
+	if fleet.ships.size() + GameState.ships_owed \
+			+ GameState.pending_orders_of(craft_building_id, GameState.PRODUCT_SHIP) \
 			>= GameState.max_fleet_size():
 		craft_status.text = "Fleet is full (%d slots)" % GameState.max_fleet_size()
 		return
@@ -484,6 +514,24 @@ func _on_load_ore() -> void:
 	_refresh_load_ore()
 
 
+func _on_store_ore() -> void:
+	if craft_building_id == 0:
+		return
+	var moved: int = GameState.unload_into_building(craft_building_id)
+	_refresh_craft_status()
+	if moved > 0:
+		craft_status.text = "Stored %d ore here      %s" % [moved, craft_status.text]
+
+
+func _on_craft_transporter() -> void:
+	if craft_building_id == 0:
+		return
+	if not GameState.queue_order(craft_building_id, GameState.PRODUCT_TRANSPORTER):
+		craft_status.text = "Build a Transport Hub first - a transporter needs somewhere to be stationed"
+		return
+	_refresh_craft_status()
+
+
 func _on_formation_changed() -> void:
 	fleet.apply_formation()
 

GameState.gd

@@ -277,7 +277,7 @@ func add_building(type: String, at_position: Vector2) -> int:
 	var id: int = next_building_id
 	next_building_id += 1
 	buildings.append({
-		"id": id, "type": type, "position": at_position, "stock": 0, "queued": 0,
+		"id": id, "type": type, "position": at_position, "stock": 0, "orders": [],
 	})
 	return id
 
@@ -289,12 +289,22 @@ func find_building(id: int) -> Dictionary:
 	return {}
 
 
-func production_cost(type: String) -> int:
-	# What one order out of this building costs it. 0 means it produces
-	# nothing and cannot be ordered from.
-	if type == BUILDING_SHIP_CRAFTER:
+const PRODUCT_SHIP: String = "interceptor"
+const PRODUCT_TRANSPORTER: String = "transporter"
+
+const TRANSPORTER_COST: int = 10
+
+
+func product_cost(product: String) -> int:
+	if product == PRODUCT_TRANSPORTER:
+		return TRANSPORTER_COST
 	return SHIP_COST
-	return 0
+
+
+func can_produce(type: String) -> bool:
+	# Only the ship crafter builds anything. The hub STATIONS transporters,
+	# it does not make them (#12).
+	return type == BUILDING_SHIP_CRAFTER
 
 
 func building_stock(id: int) -> int:
@@ -304,7 +314,29 @@ func building_stock(id: int) -> int:
 
 func pending_orders(id: int) -> int:
 	var b: Dictionary = find_building(id)
-	return 0 if b.is_empty() else int(b.get("queued", 0))
+	return 0 if b.is_empty() else (b.get("orders", []) as Array).size()
+
+
+func pending_orders_of(id: int, product: String) -> int:
+	var b: Dictionary = find_building(id)
+	if b.is_empty():
+		return 0
+	var n: int = 0
+	for o in b.get("orders", []):
+		if o == product:
+			n += 1
+	return n
+
+
+func outstanding_cost(id: int) -> int:
+	# What this building still needs delivered to clear everything queued.
+	var b: Dictionary = find_building(id)
+	if b.is_empty():
+		return 0
+	var need: int = 0
+	for o in b.get("orders", []):
+		need += product_cost(o)
+	return maxi(need - int(b.get("stock", 0)), 0)
 
 
 func deposit_to_building(id: int, amount: int) -> int:
@@ -317,28 +349,43 @@ func deposit_to_building(id: int, amount: int) -> int:
 	return amount
 
 
-func queue_order(id: int) -> bool:
+func queue_order(id: int, product: String = PRODUCT_SHIP) -> bool:
 	var b: Dictionary = find_building(id)
-	if b.is_empty() or production_cost(b.type) <= 0:
+	if b.is_empty() or not can_produce(b.type):
 		return false
-	b.queued = int(b.get("queued", 0)) + 1
+	if product == PRODUCT_TRANSPORTER and not has_transport_hub():
+		# Nowhere to station it. Refused rather than queued, so the player is
+		# told now instead of watching an order sit forever.
+		return false
+	(b.orders as Array).append(product)
 	return true
 
 
 func _advance_production() -> void:
 	for b in buildings:
-		var cost: int = production_cost(b.type)
-		if cost <= 0:
+		if not can_produce(b.type):
 			continue
 		# `while`, not `if`: a delivery big enough to cover several queued
 		# orders should clear them all rather than dribbling one out per
 		# frame.
-		while int(b.get("queued", 0)) > 0 and int(b.get("stock", 0)) >= cost:
+		var orders: Array = b.get("orders", [])
+		while not orders.is_empty():
+			var product: String = String(orders[0])
+			var cost: int = product_cost(product)
+			if int(b.get("stock", 0)) < cost:
+				break
+			if product == PRODUCT_TRANSPORTER and nearest_hub_to(b.position).is_empty():
+				# Every hub was demolished while this sat in the queue. Leave
+				# it queued and the stock untouched rather than producing a
+				# vessel with nowhere to live.
+				break
 			b.stock = int(b.stock) - cost
-			b.queued = int(b.queued) - 1
-			if b.type == BUILDING_SHIP_CRAFTER:
+			orders.pop_front()
+			if product == PRODUCT_TRANSPORTER:
+				_station_transporter(b.position)
+			else:
 				ships_owed += 1
-			order_completed.emit(int(b.id), String(b.type))
+			order_completed.emit(int(b.id), product)
 
 
 func has_mothership() -> bool:
@@ -470,6 +517,7 @@ func _process(delta: float) -> void:
 	# keep completing - while the player is on a planet's surface or nowhere
 	# near either.
 	_advance_production()
+	_advance_transporters(delta)
 	if extractors.is_empty():
 		return
 	for e in extractors:
@@ -486,6 +534,154 @@ func _process(delta: float) -> void:
 			e.progress -= 1.0
 
 
+# --- transporters (#19) ---------------------------------------------------
+
+# Vessels stationed at a transport hub that fetch ore from the mothership and
+# deliver it to whichever building is waiting on it.
+#
+# Simulated HERE rather than by any node, exactly like the extractor haulers
+# above and for the same reason: a route the player is nowhere near still has
+# to run. `progress` drives both the drawn position and the moment the ore
+# actually moves, so what you see and what happens cannot drift apart.
+#
+# Entries are {"hub_id", "state", "target_id", "carrying", "progress",
+# "from", "to"}.
+const TRANSPORTER_SPEED: float = 340.0
+
+const TRANSPORTER_IDLE: String = "idle"
+const TRANSPORTER_TO_MOTHERSHIP: String = "to_mothership"
+const TRANSPORTER_TO_BUILDING: String = "to_building"
+const TRANSPORTER_RETURNING: String = "returning"
+
+var transporters: Array = []
+
+
+func has_transport_hub() -> bool:
+	return not nearest_hub_to(Vector2.ZERO).is_empty()
+
+
+func nearest_hub_to(at: Vector2) -> Dictionary:
+	var best: Dictionary = {}
+	var best_d: float = INF
+	for b in buildings:
+		if b.type != BUILDING_TRANSPORT_HUB:
+			continue
+		var d: float = at.distance_squared_to(b.position)
+		if d < best_d:
+			best_d = d
+			best = b
+	return best
+
+
+func _station_transporter(built_at: Vector2) -> void:
+	# Built at the crafter, then it flies itself to the nearest hub and waits
+	# there for orders (#12).
+	var hub: Dictionary = nearest_hub_to(built_at)
+	if hub.is_empty():
+		return
+	transporters.append({
+		"hub_id": int(hub.id), "state": TRANSPORTER_RETURNING, "target_id": 0,
+		"carrying": 0, "progress": 0.0, "from": built_at, "to": hub.position,
+	})
+
+
+func transporter_position(t: Dictionary) -> Vector2:
+	return (t.from as Vector2).lerp(t.to as Vector2, clampf(t.progress, 0.0, 1.0))
+
+
+func _hub_position(hub_id: int) -> Variant:
+	var hub: Dictionary = find_building(hub_id)
+	return null if hub.is_empty() else hub.position
+
+
+func _begin_leg(t: Dictionary, from: Vector2, to: Vector2, state: String) -> void:
+	t.from = from
+	t.to = to
+	t.state = state
+	t.progress = 0.0
+
+
+func _transporter_inbound_to(building_id: int) -> bool:
+	for t in transporters:
+		if t.state != TRANSPORTER_IDLE and int(t.target_id) == building_id:
+			return true
+	return false
+
+
+func _dispatch_transporters() -> void:
+	var mothership: Variant = get_mothership_position()
+	if mothership == null:
+		return  # nowhere to load from
+	for b in buildings:
+		if outstanding_cost(int(b.id)) <= 0:
+			continue
+		# One at a time per building: without this every idle transporter
+		# would be sent after the same shortfall and they would all arrive
+		# carrying ore nobody needs any more.
+		if _transporter_inbound_to(int(b.id)):
+			continue
+		var chosen: Dictionary = {}
+		var best_d: float = INF
+		for t in transporters:
+			if t.state != TRANSPORTER_IDLE:
+				continue
+			var here: Vector2 = transporter_position(t)
+			var d: float = here.distance_squared_to(b.position)
+			if d < best_d:
+				best_d = d
+				chosen = t
+		if chosen.is_empty():
+			return  # every transporter is busy
+		chosen.target_id = int(b.id)
+		_begin_leg(chosen, transporter_position(chosen), mothership, TRANSPORTER_TO_MOTHERSHIP)
+
+
+func _advance_transporters(delta: float) -> void:
+	if transporters.is_empty():
+		return
+	_dispatch_transporters()
+	for t in transporters:
+		if t.state == TRANSPORTER_IDLE:
+			continue
+		var distance: float = (t.from as Vector2).distance_to(t.to as Vector2)
+		var leg: float = maxf(distance / TRANSPORTER_SPEED, 0.0001)
+		t.progress += delta / leg
+		if t.progress < 1.0:
+			continue
+		t.progress = 1.0
+		_arrive(t)
+
+
+func _arrive(t: Dictionary) -> void:
+	var here: Vector2 = t.to
+	var hub_pos: Variant = _hub_position(int(t.hub_id))
+	match t.state:
+		TRANSPORTER_TO_MOTHERSHIP:
+			var target: Dictionary = find_building(int(t.target_id))
+			var want: int = outstanding_cost(int(t.target_id))
+			var take: int = mini(want, rocks)
+			if take <= 0 or target.is_empty():
+				# Nothing to carry, or the building is gone. Go home empty.
+				t.target_id = 0
+				_begin_leg(t, here, hub_pos if hub_pos != null else here, TRANSPORTER_RETURNING)
+				return
+			rocks -= take
+			t.carrying = take
+			_begin_leg(t, here, target.position, TRANSPORTER_TO_BUILDING)
+		TRANSPORTER_TO_BUILDING:
+			# The ore moves at exactly the moment the vessel arrives.
+			if deposit_to_building(int(t.target_id), int(t.carrying)) <= 0:
+				# Building demolished in transit - put the ore back rather
+				# than quietly destroying it.
+				rocks += int(t.carrying)
+			t.carrying = 0
+			t.target_id = 0
+			_begin_leg(t, here, hub_pos if hub_pos != null else here, TRANSPORTER_RETURNING)
+		TRANSPORTER_RETURNING:
+			t.state = TRANSPORTER_IDLE
+			t.progress = 1.0
+
+
 func can_afford(cost: int) -> bool:
 	return rocks >= cost
 

Main.tscn

@@ -22,6 +22,7 @@
 [ext_resource type="Script" path="res://NeonPanel.gd" id="20"]
 [ext_resource type="Script" path="res://SkillTreeView.gd" id="21"]
 [ext_resource type="Script" path="res://CargoCounter.gd" id="22"]
+[ext_resource type="Script" path="res://TransporterField.gd" id="23"]
 
 [sub_resource type="ShaderMaterial" id="1"]
 shader = ExtResource("5")
@@ -72,6 +73,9 @@ script = ExtResource("14")
 [node name="HaulerField" type="Node2D" parent="."]
 script = ExtResource("18")
 
+[node name="TransporterField" type="Node2D" parent="."]
+script = ExtResource("23")
+
 [node name="BuildController" type="Node2D" parent="."]
 script = ExtResource("15")
 
@@ -609,8 +613,8 @@ anchor_left = 0.5
 anchor_right = 0.5
 anchor_top = 0.5
 anchor_bottom = 0.5
-offset_left = -74
-offset_right = 74
+offset_left = -234
+offset_right = -86
 offset_top = -74
 offset_bottom = 74
 script = ExtResource("10")
@@ -622,14 +626,70 @@ anchor_left = 0.5
 anchor_right = 0.5
 anchor_top = 0.5
 anchor_bottom = 0.5
-offset_left = -260
-offset_right = 260
+offset_left = -300
+offset_right = -20
 offset_top = 100
 offset_bottom = 200
-theme_override_font_sizes/font_size = 60
+theme_override_font_sizes/font_size = 32
 text = "Interceptor"
 horizontal_alignment = 1
 
+[node name="TransporterButton" type="Control" parent="UI/CraftMenu"]
+anchor_left = 0.5
+anchor_right = 0.5
+anchor_top = 0.5
+anchor_bottom = 0.5
+offset_left = 86
+offset_right = 234
+offset_top = -74
+offset_bottom = 74
+script = ExtResource("10")
+icon = 12
+glow_color = Color(0.95, 0.55, 0.85, 1)
+
+[node name="TransporterLabel" type="Label" parent="UI/CraftMenu"]
+mouse_filter = 2
+anchor_left = 0.5
+anchor_right = 0.5
+anchor_top = 0.5
+anchor_bottom = 0.5
+offset_left = 20
+offset_right = 300
+offset_top = 96
+offset_bottom = 176
+theme_override_font_sizes/font_size = 32
+autowrap_mode = 2
+text = "Transporter"
+horizontal_alignment = 1
+
+[node name="StoreOreButton" type="Control" parent="UI/CraftMenu"]
+anchor_left = 0.5
+anchor_top = 1.0
+anchor_right = 0.5
+anchor_bottom = 1.0
+offset_left = -74
+offset_top = -304
+offset_right = 74
+offset_bottom = -156
+script = ExtResource("10")
+icon = 3
+glow_color = Color(1, 0.78, 0.25, 1)
+
+[node name="StoreOreLabel" type="Label" parent="UI/CraftMenu"]
+mouse_filter = 2
+anchor_left = 0.5
+anchor_top = 1.0
+anchor_right = 0.5
+anchor_bottom = 1.0
+offset_left = -260
+offset_top = -148
+offset_right = 260
+offset_bottom = -24
+theme_override_font_sizes/font_size = 32
+autowrap_mode = 2
+text = "Store ore here"
+horizontal_alignment = 1
+
 [node name="CloseButton" type="Control" parent="UI/CraftMenu"]
 anchor_left = 1.0
 anchor_right = 1.0
@@ -794,33 +854,41 @@ horizontal_alignment = 1
 
 [node name="UnlockButton" type="Control" parent="UI/SkillMenu"]
 anchor_left = 0.5
+anchor_top = 1.0
 anchor_right = 0.5
+anchor_bottom = 1.0
 offset_left = -74.0
-offset_top = 1090.0
+offset_top = -304.0
 offset_right = 74.0
-offset_bottom = 1238.0
+offset_bottom = -156.0
 script = ExtResource("10")
 icon = 5
 glow_color = Color(0.45, 0.9, 0.55, 1)
 
 [node name="LoadOreButton" type="Control" parent="UI/SkillMenu"]
 anchor_left = 0.5
+anchor_top = 1.0
 anchor_right = 0.5
+anchor_bottom = 1.0
 offset_left = -256.0
-offset_top = 1090.0
+offset_top = -304.0
 offset_right = -108.0
-offset_bottom = 1238.0
+offset_bottom = -156.0
 script = ExtResource("10")
 icon = 4
 glow_color = Color(1, 0.78, 0.25, 1)
 
 [node name="LoadOreLabel" type="Label" parent="UI/SkillMenu"]
+mouse_filter = 2
 anchor_left = 0.5
+anchor_top = 1.0
 anchor_right = 0.5
-offset_left = -300.0
-offset_top = 1246.0
-offset_right = -64.0
-offset_bottom = 1296.0
+anchor_bottom = 1.0
+offset_left = -330.0
+offset_top = -150.0
+offset_right = -30.0
+offset_bottom = -14.0
+theme_override_font_sizes/font_size = 28
 horizontal_alignment = 1
 autowrap_mode = 2
 text = "Load ore"

Transporter.gd

@@ -0,0 +1,38 @@
+extends Node2D
+
+# Purely visual: a transport vessel running a hub -> mothership -> building
+# supply route. Carries no state of its own; GameState owns the simulation
+# and TransporterField creates, positions and frees this to match.
+
+const HULL_COLOR: Color = Color(0.95, 0.55, 0.85)
+
+var laden: bool = false
+
+
+func _ready() -> void:
+	add_to_group("transporters")
+	z_index = -1
+	queue_redraw()
+
+
+func set_laden(value: bool) -> void:
+	if laden == value:
+		return
+	laden = value
+	queue_redraw()
+
+
+func _draw() -> void:
+	# Squat and boxy, in the transport hub's own magenta, so it reads as
+	# "belongs to the hub" and not as an extractor hauler (green) or a fleet
+	# vessel (sharp cyan triangle).
+	var hull: PackedVector2Array = PackedVector2Array([
+		Vector2(0, -16), Vector2(10, -4), Vector2(10, 14), Vector2(-10, 14), Vector2(-10, -4),
+	])
+	NeonDraw.draw_glowing_polygon(self, hull, HULL_COLOR, 1.0)
+	if laden:
+		# A visible payload, so a loaded run is distinguishable from a
+		# deadhead back to the hub at a glance.
+		NeonDraw.draw_glowing_polygon(self, PackedVector2Array([
+			Vector2(-5, 0), Vector2(5, 0), Vector2(5, 9), Vector2(-5, 9),
+		]), HULL_COLOR, 0.85)

Transporter.gd.uid

@@ -0,0 +1 @@
+uid://u8bqm1f03l2y

Transporter.tscn

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

TransporterField.gd

@@ -0,0 +1,51 @@
+extends Node2D
+
+# Draws the transport vessels GameState is simulating, and only while they
+# are somewhere the player could see them. Same arrangement as HaulerField,
+# and for the same reason: the simulation is authoritative and the visuals
+# are optional, so a run happening far away costs nothing but still moves
+# ore. Position comes from the very same `progress` that decides when the
+# ore actually changes hands.
+
+@export var visible_radius: float = 2600.0
+
+@onready var fleet: Node2D = get_node("../Fleet")
+
+var transporter_scene: PackedScene = preload("res://Transporter.tscn")
+# index into GameState.transporters -> live node
+var active: Dictionary = {}
+
+
+func _process(_delta: float) -> void:
+	var centre: Vector2 = fleet.get_centroid()
+
+	for i in range(GameState.transporters.size()):
+		var t: Dictionary = GameState.transporters[i]
+		var pos: Vector2 = GameState.transporter_position(t)
+		if pos.distance_to(centre) > visible_radius:
+			_despawn(i)
+			continue
+
+		var node: Node2D = active.get(i)
+		if node == null or not is_instance_valid(node):
+			node = transporter_scene.instantiate()
+			get_parent().add_child(node)
+			active[i] = node
+
+		var previous: Vector2 = node.position
+		node.position = pos
+		node.set_laden(int(t.carrying) > 0)
+		var travel: Vector2 = pos - previous
+		if travel.length() > 0.5:
+			node.rotation = travel.angle() + PI / 2.0
+
+	for key in active.keys():
+		if key >= GameState.transporters.size():
+			_despawn(key)
+
+
+func _despawn(index: int) -> void:
+	var node: Node2D = active.get(index)
+	if node != null and is_instance_valid(node):
+		node.queue_free()
+	active.erase(index)

TransporterField.gd.uid

@@ -0,0 +1 @@
+uid://mrx6p58dog66

tests/_build_menu_preview.gd.uid

@@ -0,0 +1 @@
+uid://cuns23tjgn7fg

tests/_cargo_readout_preview.gd.uid

@@ -0,0 +1 @@
+uid://djp66g3saubh4

tests/_craft_menu_preview.gd

@@ -0,0 +1,27 @@
+extends Node2D
+
+# Preview, not a test. Opens the CraftMenu so its layout can be checked on a
+# real viewport - the mothership's "Load ore" label was falling off the bottom
+# of shorter screens, which no headless test can see.
+#
+#   bash tests/screenshot.sh res://tests/_craft_menu_preview.tscn /tmp/m.png 20 720x1280
+#   ... and again at 720x960 to check a shorter screen format.
+
+
+func _ready() -> void:
+	GameState.buildings.clear()
+	GameState.extractors.clear()
+	GameState.transporters.clear()
+	GameState.rocks = 180
+	GameState.fleet_cargo = 24
+	GameState.unlocked = ["shipyards", "logistics", "freight"]
+	var main: Node = load("res://Main.tscn").instantiate()
+	add_child(main)
+	main.get_node("BuildingField").place(GameState.BUILDING_TRANSPORT_HUB, Vector2(400.0, 0.0))
+	var bc: Node = main.get_node("BuildController")
+	bc.craft_building_id = 1
+	main.get_node("UI/CraftMenu").visible = true
+	if "Craft" == "Craft":
+		bc._refresh_craft_status()
+	else:
+		bc._refresh_load_ore()

tests/_craft_menu_preview.tscn

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

tests/_skill_menu_preview.gd

@@ -1,29 +1,27 @@
 extends Node2D
 
-# Preview scene - NOT run by run_tests.sh (underscore prefix). Opens the
-# mothership's research tree with one branch already bought and a node
-# selected, so the laid-out tree, its state colours and the detail panel can
-# all be checked in one render.
+# Preview, not a test. Opens the SkillMenu so its layout can be checked on a
+# real viewport - the mothership's "Load ore" label was falling off the bottom
+# of shorter screens, which no headless test can see.
 #
-#   bash tests/screenshot.sh res://tests/_skill_menu_preview.tscn out.png 30 720x1280
+#   bash tests/screenshot.sh res://tests/_skill_menu_preview.tscn /tmp/m.png 20 720x1280
+#   ... and again at 720x960 to check a shorter screen format.
 
 
 func _ready() -> void:
 	GameState.buildings.clear()
 	GameState.extractors.clear()
-	GameState.reset_progression()
-	GameState.rocks = 60
-	# One branch researched, so the render shows all three node states at
-	# once: done, reachable, and still locked further out.
-	GameState.unlock("shipyards")
-	GameState.unlock("coordination")
-
+	GameState.transporters.clear()
+	GameState.rocks = 180
+	GameState.fleet_cargo = 24
+	GameState.unlocked = ["shipyards", "logistics", "freight"]
 	var main: Node = load("res://Main.tscn").instantiate()
 	add_child(main)
-	main.get_node("AsteroidField").set_process(false)
-	main.get_node("EnemySpawner").set_process(false)
-
-	var controller: Node = main.get_node("BuildController")
-	controller.skill_menu.visible = true
-	controller.skill_tree.selected_id = "wing"
-	controller._refresh_skill_menu("wing")
+	main.get_node("BuildingField").place(GameState.BUILDING_TRANSPORT_HUB, Vector2(400.0, 0.0))
+	var bc: Node = main.get_node("BuildController")
+	bc.craft_building_id = 1
+	main.get_node("UI/SkillMenu").visible = true
+	if "Skill" == "Craft":
+		bc._refresh_craft_status()
+	else:
+		bc._refresh_load_ore()

tests/_transporter_preview.gd

@@ -0,0 +1,38 @@
+extends Node2D
+
+# Preview, not a test. A transporter mid-run between the mothership and a
+# building it is supplying, so the #19 vessel can actually be looked at
+# alongside the hub that stations it. Headless draws no pixels.
+#
+#   bash tests/screenshot.sh res://tests/_transporter_preview.tscn /tmp/t.png 25 1280x720
+
+
+func _ready() -> void:
+	GameState.buildings.clear()
+	GameState.extractors.clear()
+	GameState.transporters.clear()
+	GameState.rocks = 200
+	GameState.add_building(GameState.BUILDING_MOTHERSHIP, Vector2(-420.0, 0.0))
+	GameState.add_building(GameState.BUILDING_TRANSPORT_HUB, Vector2(420.0, 0.0))
+
+	# One laden, mid-leg, and one running home empty, so both states show.
+	GameState.transporters.append({
+		"hub_id": 2, "state": GameState.TRANSPORTER_TO_BUILDING, "target_id": 2,
+		"carrying": 8, "progress": 0.45,
+		"from": Vector2(-420.0, 0.0), "to": Vector2(420.0, 0.0),
+	})
+	GameState.transporters.append({
+		"hub_id": 2, "state": GameState.TRANSPORTER_RETURNING, "target_id": 0,
+		"carrying": 0, "progress": 0.5,
+		"from": Vector2(-380.0, 150.0), "to": Vector2(420.0, 150.0),
+	})
+
+	var main: Node = load("res://Main.tscn").instantiate()
+	add_child(main)
+	main.get_node("AsteroidField").set_process(false)
+	main.get_node("EnemySpawner").set_process(false)
+	# Freeze the simulation so the vessels stay where they were placed.
+	GameState.set_process(false)
+	main.get_node("Fleet").move_to(Vector2(0.0, 260.0))
+	var cam: Camera2D = main.get_node("Camera2D")
+	cam.zoom = Vector2(0.85, 0.85)

tests/_transporter_preview.gd.uid

@@ -0,0 +1 @@
+uid://cqc5de83g4tr2

tests/_transporter_preview.tscn

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

tests/test_building_stock_queue.gd.uid

@@ -0,0 +1 @@
+uid://b0364sukgpwow

tests/test_cargo_readout.gd.uid

@@ -0,0 +1 @@
+uid://bpldq0su02w1v

tests/test_manual_supply_route.gd.uid

@@ -0,0 +1 @@
+uid://bjkqin5w5tah2

tests/test_transport_hub_building.gd.uid

@@ -0,0 +1 @@
+uid://ctplk4adbsi3a

tests/test_transporter_supply.gd

@@ -0,0 +1,207 @@
+extends SceneTree
+
+# Headless gameplay test: run with
+#   godot --headless -s res://tests/test_transporter_supply.gd
+# Forgejo #19 (part 6 of #12): transporters stationed at a hub fetch ore from
+# the mothership and deliver it to whichever building is waiting on it, with
+# no player input at all.
+#
+# Verifies:
+#   1. a transporter is built at the CRAFTER and takes itself to the nearest
+#      hub, rather than appearing at the hub out of nowhere
+#   2. a queued order the crafter cannot pay for is fulfilled end to end
+#      automatically - the whole point of the ticket
+#   3. ore is conserved across the entire route (bank + hold + every
+#      building's stock), at every step, not just at the end
+#   4. ore leaves the bank when it is LOADED, not when the order is placed -
+#      the vessel is carrying something real
+#   5. transporters are not ordered when there is no hub to station them at
+#   6. no unbounded node accumulation: the fleet of transporters is exactly
+#      what was built, however many runs they make
+
+var game_state: Node
+var scene: Node
+var fleet: Node
+var field: Node
+var crafter_id: int = 0
+var hub_id: int = 0
+var stage: int = 0
+var elapsed: float = 0.0
+var total_at_start: int = 0
+var bank_when_ordered: int = 0
+var conservation_broken: bool = false
+# Ore legitimately consumed by completed production. Conservation means
+# "nothing vanishes in TRANSIT", not "the total never falls" - building a
+# vessel spends ore, and that is the one way it is allowed to leave.
+var consumed: int = 0
+
+const MOTHERSHIP_AT: Vector2 = Vector2(0.0, 0.0)
+const HUB_AT: Vector2 = Vector2(600.0, 200.0)
+const CRAFTER_AT: Vector2 = Vector2(900.0, -300.0)
+
+
+func _total() -> int:
+	var sum: int = game_state.rocks + game_state.fleet_cargo
+	for b in game_state.buildings:
+		sum += int(b.get("stock", 0))
+	for t in game_state.transporters:
+		sum += int(t.get("carrying", 0))
+	return sum
+
+
+func _initialize() -> void:
+	game_state = root.get_node("GameState")
+	game_state.buildings.clear()
+	game_state.extractors.clear()
+	game_state.transporters.clear()
+	game_state.rocks = 200
+	game_state.fleet_cargo = 0
+	game_state.ships_owed = 0
+	game_state.unlocked = ["shipyards", "logistics", "freight", "coordination", "wing", "squadron", "armada"]
+	scene = load("res://Main.tscn").instantiate()
+	root.add_child(scene)
+	fleet = scene.get_node("Fleet")
+	field = scene.get_node("BuildingField")
+	game_state.order_completed.connect(_on_order_completed)
+
+
+func _on_order_completed(_building_id: int, product: String) -> void:
+	consumed += game_state.product_cost(product)
+
+
+func _process(delta: float) -> bool:
+	elapsed += delta
+
+	# --- 3. conservation, checked EVERY tick ------------------------------
+	# Ore in flight is the easy thing to lose: a leg that loads without
+	# debiting, or delivers without crediting, would show up here and nowhere
+	# else. Checked continuously rather than at the end, so it cannot be
+	# masked by a later correction.
+	if stage >= 2 and _total() + consumed != total_at_start:
+		conservation_broken = true
+
+	match stage:
+		0:
+			scene.get_node("AsteroidField").set_process(false)
+			scene.get_node("EnemySpawner").set_process(false)
+			for a in get_nodes_in_group("asteroids"):
+				if is_instance_valid(a):
+					a.queue_free()
+
+			field.place(GameState.BUILDING_MOTHERSHIP, MOTHERSHIP_AT)
+			field.place(GameState.BUILDING_SHIP_CRAFTER, CRAFTER_AT)
+			crafter_id = int(game_state.buildings[-1].id)
+
+			# --- 5. no hub yet: a transporter cannot be ordered ----------
+			if game_state.queue_order(crafter_id, GameState.PRODUCT_TRANSPORTER):
+				print("TEST_TRANSPORTER_SUPPLY: FAIL (ordered a transporter with no hub to station it at)")
+				quit(1)
+				return true
+			print("no hub -> transporter order refused")
+
+			field.place(GameState.BUILDING_TRANSPORT_HUB, HUB_AT)
+			hub_id = int(game_state.buildings[-1].id)
+			elapsed = 0.0
+			stage = 1
+			return false
+		1:
+			if elapsed < 0.2:
+				return false
+			# --- 1. build a transporter at the crafter ------------------
+			if not game_state.queue_order(crafter_id, GameState.PRODUCT_TRANSPORTER):
+				print("TEST_TRANSPORTER_SUPPLY: FAIL (could not order a transporter with a hub built)")
+				quit(1)
+				return true
+			game_state.deposit_to_building(crafter_id, GameState.TRANSPORTER_COST)
+			elapsed = 0.0
+			stage = 2
+			total_at_start = _total()
+			return false
+		2:
+			if elapsed < 0.3:
+				return false
+			if game_state.transporters.size() != 1:
+				print("TEST_TRANSPORTER_SUPPLY: FAIL (built %d transporters from one order)" % game_state.transporters.size())
+				quit(1)
+				return true
+			var t: Dictionary = game_state.transporters[0]
+			if int(t.hub_id) != hub_id:
+				print("TEST_TRANSPORTER_SUPPLY: FAIL (transporter did not take the nearest hub)")
+				quit(1)
+				return true
+			# It must fly FROM the crafter TO the hub, not appear at the hub.
+			# Checked on the leg's endpoints rather than its current position,
+			# which is already partway there by now - and being partway is
+			# the correct behaviour.
+			if (t.from as Vector2).distance_to(CRAFTER_AT) > 1.0:
+				print("TEST_TRANSPORTER_SUPPLY: FAIL (transporter's first leg starts at %s, not at the crafter that built it)" % t.from)
+				quit(1)
+				return true
+			if (t.to as Vector2).distance_to(HUB_AT) > 1.0:
+				print("TEST_TRANSPORTER_SUPPLY: FAIL (transporter's first leg does not end at the hub: %s)" % t.to)
+				quit(1)
+				return true
+			print("transporter built at the crafter, heading for hub %d" % hub_id)
+			elapsed = 0.0
+			stage = 3
+			return false
+		3:
+			# Give it time to reach the hub and go idle.
+			if elapsed < 4.0:
+				return false
+			if game_state.transporters[0].state != GameState.TRANSPORTER_IDLE:
+				print("TEST_TRANSPORTER_SUPPLY: FAIL (never settled at its hub: state=%s)" % game_state.transporters[0].state)
+				quit(1)
+				return true
+			print("stationed at the hub, idle")
+
+			# --- 2 + 4. an order it cannot pay for ----------------------
+			game_state.queue_order(crafter_id, GameState.PRODUCT_SHIP)
+			bank_when_ordered = game_state.rocks
+			elapsed = 0.0
+			stage = 4
+			return false
+		4:
+			# One tick: placing the order must not touch the bank.
+			if elapsed < 0.1:
+				return false
+			if game_state.rocks != bank_when_ordered:
+				print("TEST_TRANSPORTER_SUPPLY: FAIL (bank moved on placing the order, before anything was loaded)")
+				quit(1)
+				return true
+			print("order placed, bank untouched at %d" % game_state.rocks)
+			elapsed = 0.0
+			stage = 5
+			return false
+		5:
+			# --- 2. the whole run, with no player input -----------------
+			if game_state.pending_orders(crafter_id) > 0:
+				if elapsed > 25.0:
+					print("TEST_TRANSPORTER_SUPPLY: FAIL (order never fulfilled: transporter state=%s carrying=%d crafter stock=%d)" % [
+						game_state.transporters[0].state,
+						int(game_state.transporters[0].carrying),
+						game_state.building_stock(crafter_id),
+					])
+					quit(1)
+					return true
+				return false
+			if conservation_broken:
+				print("TEST_TRANSPORTER_SUPPLY: FAIL (ore created or destroyed somewhere along the route)")
+				quit(1)
+				return true
+			print("order fulfilled automatically in %.1fs, no player input" % elapsed)
+
+			# --- 6. no vessel accumulation ------------------------------
+			if game_state.transporters.size() != 1:
+				print("TEST_TRANSPORTER_SUPPLY: FAIL (%d transporters exist after the run, one was built)" % game_state.transporters.size())
+				quit(1)
+				return true
+			print("still exactly 1 transporter after a full round trip")
+			print("bank=%d crafter stock=%d total=%d + %d consumed = %d (started %d)" % [
+				game_state.rocks, game_state.building_stock(crafter_id), _total(),
+				consumed, _total() + consumed, total_at_start
+			])
+			print("TEST_TRANSPORTER_SUPPLY: PASS")
+			quit(0)
+			return true
+	return false

tests/test_transporter_supply.gd.uid

@@ -0,0 +1 @@
+uid://dxu5orxbivfpa