diff --git a/BuildController.gd b/BuildController.gd
index b598703..1d33801 100644
--- a/BuildController.gd
+++ b/BuildController.gd
@@ -1,6 +1,7 @@
 extends Node2D
 
 const BUILDING_DEFINITIONS = preload("res://BuildingDefinitions.gd")
+const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")
 
 # Space-side building UI. Owns:
 #   - the build menu (place a mothership, ship crafter or command centre)
@@ -32,6 +33,10 @@ const BUILDING_DEFINITIONS = preload("res://BuildingDefinitions.gd")
 	get_node("../UI/LabMenu/VesselC"),
 ]
 @onready var lab_vessel_label: Label = get_node("../UI/LabMenu/VesselLabel")
+@onready var lab_vessel_labels: Array = [
+	get_node("../UI/LabMenu/VesselALabel"), get_node("../UI/LabMenu/VesselBLabel"),
+	get_node("../UI/LabMenu/VesselCLabel"),
+]
 @onready var lab_detail: Label = get_node("../UI/LabMenu/DetailLabel")
 @onready var lab_status: Label = get_node("../UI/LabMenu/StatusLabel")
 @onready var lab_buy_button: IconButton = get_node("../UI/LabMenu/BuyButton")
@@ -98,6 +103,12 @@ var lab_building_id: int = 0
 @onready var craft_interceptor_label: Label = get_node("../UI/CraftMenu/InterceptorLabel")
 @onready var craft_transporter_label: Label = get_node("../UI/CraftMenu/TransporterLabel")
 @onready var craft_shield_label: Label = get_node("../UI/CraftMenu/ShieldLabel")
+@onready var craft_vessel_buttons: Array = [
+	craft_interceptor_button, craft_shield_button, craft_transporter_button,
+]
+@onready var craft_vessel_labels: Array = [
+	craft_interceptor_label, craft_shield_label, craft_transporter_label,
+]
 
 # --- the transfer panel (#24) ---------------------------------------------
 # Ore used to be moved from inside whichever panel happened to be open: "load
@@ -159,7 +170,6 @@ func _ready() -> void:
 	build_button.pressed.connect(_on_build_pressed)
 	build_close_button.pressed.connect(_close_build_menu)
 	_configure_build_menu_entries()
-	craft_shield_button.pressed.connect(_on_craft_shield)
 	lab_close_button.pressed.connect(func(): lab_menu.visible = false)
 	lab_buy_button.pressed.connect(_on_lab_buy)
 	for i in range(lab_vessel_buttons.size()):
@@ -172,8 +182,9 @@ func _ready() -> void:
 	action_button.pressed.connect(_on_context_action_pressed)
 	building_action_button.pressed.connect(_on_action_pressed)
 
-	craft_interceptor_button.pressed.connect(_on_craft_interceptor)
-	craft_transporter_button.pressed.connect(_on_craft_transporter)
+	for i in range(mini(craft_vessel_buttons.size(), VESSEL_DEFINITIONS.all().size())):
+		var definition: Resource = VESSEL_DEFINITIONS.all()[i]
+		craft_vessel_buttons[i].pressed.connect(_on_craft_vessel.bind(definition.definition_id))
 	craft_close_button.pressed.connect(func(): craft_menu.visible = false)
 
 	transfer_button.pressed.connect(_on_transfer_pressed)
@@ -692,26 +703,19 @@ func _refresh_craft_status() -> void:
 	# Prices live with the buttons they describe. The top of the screen is
 	# intentionally reserved for the shared resource bar and a short action
 	# message; repeating fleet, queue and transport counts here buried the UI.
-	craft_interceptor_label.text = "Interceptor\n%d ore" % GameState.SHIP_COST
-	craft_transporter_label.text = "Transporter\n%d ore" % GameState.TRANSPORTER_COST
-	craft_shield_label.text = "Shield Vessel\n%d ore" % GameState.SHIELD_COST
 	craft_status.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() \
-		and GameState.can_station_transporter()
-	craft_transporter_button.queue_redraw()
-
-	craft_shield_button.enabled = GameState.shield_vessel_unlocked()
-	craft_shield_button.queue_redraw()
-
-	# Fleet capacity no longer gates ORDERING (#23). A finished vessel waits
-	# at the mothership until the player crews it, so a full fleet is a
-	# reason not to collect one yet - not a reason the crafter cannot build.
-	# This is also what stopped the crafter being inert on a fresh save,
-	# where the fleet starts at exactly its cap.
-	craft_interceptor_button.enabled = true
-	craft_interceptor_button.queue_redraw()
+	var definitions: Array = VESSEL_DEFINITIONS.all()
+	for i in range(mini(definitions.size(), craft_vessel_buttons.size())):
+		var definition: Resource = definitions[i]
+		var button: IconButton = craft_vessel_buttons[i]
+		craft_vessel_labels[i].text = "%s\n%d ore" % [definition.display_name, definition.build_cost]
+		button.icon = definition.icon
+		button.glow_color = definition.glow_color
+		button.enabled = GameState.vessel_is_unlocked(definition.definition_id)
+		if definition.has_capability("transport"):
+			button.enabled = button.enabled and GameState.has_transport_hub() \
+				and GameState.can_station_transporter()
+		button.queue_redraw()
 	_refresh_queue()
 	if craft_message != "":
 		if Time.get_ticks_msec() < craft_message_until:
@@ -721,40 +725,40 @@ func _refresh_craft_status() -> void:
 
 
 func _on_craft_interceptor() -> void:
+	_on_craft_vessel(GameState.VESSEL_INTERCEPTOR)
+
+
+func _on_craft_vessel(vessel: String) -> void:
 	if craft_building_id == 0:
 		_say("No crafter selected - reopen this panel from the building")
 		return
-	# No affordability check: an order the crafter cannot pay for yet is
-	# QUEUED, and completes by itself once ore is delivered here (#16). But
-	# queueing silently looks identical to a dead button, so it says which
-	# happened and what the crafter is still short of.
-	GameState.queue_order(craft_building_id)
-	_report_order(GameState.PRODUCT_SHIP)
+	var definition: Resource = VESSEL_DEFINITIONS.get_definition(vessel)
+	if definition == null:
+		return
+	if not GameState.queue_order(craft_building_id, vessel):
+		if not GameState.vessel_is_unlocked(vessel):
+			_say("%s must be unlocked at a ship lab first" % definition.display_name)
+		elif definition.has_capability("transport") and not GameState.has_transport_hub():
+			_say("Build a Transport Hub first - a transporter needs somewhere to be stationed")
+		elif definition.has_capability("transport"):
+			_say("All %d berths are taken - build another hub, or research Freight Yards" %
+				GameState.transport_capacity())
+		return
+	_report_order(vessel)
 
 
 func _report_order(product: String) -> void:
 	var short: int = GameState.outstanding_cost(craft_building_id)
 	if short > 0:
 		_say("%s queued - %d more ore must be delivered here" % [
-			GameState.VESSEL_NAMES.get(product, product), short
+			GameState.vessel_name(product), short
 		])
 	else:
-		_say("%s ordered - building now" % GameState.VESSEL_NAMES.get(product, product))
+		_say("%s ordered - building now" % GameState.vessel_name(product))
 
 
 func _on_craft_transporter() -> void:
-	if craft_building_id == 0:
-		_say("No crafter selected - reopen this panel from the building")
-		return
-	if not GameState.queue_order(craft_building_id, GameState.PRODUCT_TRANSPORTER):
-		# Two different refusals, and the player needs to know WHICH.
-		if not GameState.has_transport_hub():
-			_say("Build a Transport Hub first - a transporter needs somewhere to be stationed")
-		else:
-			_say("All %d berths are taken - build another hub, or research Freight Yards" %
-				GameState.transport_capacity())
-		return
-	_refresh_craft_status()
+	_on_craft_vessel(GameState.VESSEL_TRANSPORTER)
 
 
 # --- ship lab (#5) --------------------------------------------------------
@@ -764,10 +768,13 @@ func _lab_options() -> Array:
 	# entry, because unlocking the type and upgrading it belong in the same
 	# place - and its upgrades are pointless until it exists.
 	var options: Array = []
-	if lab_vessel == GameState.VESSEL_SHIELD and not GameState.shield_vessel_unlocked():
-		options.append({"unlock": true, "name": "Unlock Shield Vessel",
-			"desc": "Lets the ship crafter build shield vessels. Its shield absorbs one lethal hit, then cycles back up.",
-			"cost": GameState.UNLOCK_SHIELD_COST})
+	var definition: Resource = VESSEL_DEFINITIONS.get_definition(lab_vessel)
+	if definition == null:
+		return options
+	if not GameState.vessel_is_unlocked(lab_vessel):
+		options.append({"unlock": true, "id": definition.unlock_id,
+			"name": definition.unlock_name, "desc": definition.unlock_description,
+			"cost": definition.unlock_cost, "icon": IconButton.Icon.UPGRADE_UNLOCK_SHIELD})
 		return options
 	for u in GameState.upgrades_for(lab_vessel):
 		options.append({"unlock": false, "id": u.id, "name": u.name, "desc": u.desc})
@@ -775,8 +782,10 @@ func _lab_options() -> Array:
 
 
 func _on_lab_vessel(index: int) -> void:
-	lab_vessel = [GameState.VESSEL_INTERCEPTOR, GameState.VESSEL_SHIELD,
-		GameState.VESSEL_TRANSPORTER][index]
+	var definitions: Array = VESSEL_DEFINITIONS.all()
+	if index < 0 or index >= definitions.size():
+		return
+	lab_vessel = definitions[index].definition_id
 	lab_choice = 0
 	_refresh_lab()
 
@@ -794,7 +803,7 @@ func _on_lab_buy() -> void:
 	if options.is_empty():
 		return
 	var choice: Dictionary = options[lab_choice]
-	var id: String = GameState.UNLOCK_SHIELD_VESSEL if choice.unlock else String(choice.id)
+	var id: String = String(choice.id)
 	if not GameState.queue_lab_research(lab_building_id, id):
 		lab_status.text = "Research is already queued or complete"
 		return
@@ -803,14 +812,17 @@ func _on_lab_buy() -> void:
 
 
 func _refresh_lab() -> void:
-	for i in range(lab_vessel_buttons.size()):
-		var this_vessel: String = [GameState.VESSEL_INTERCEPTOR, GameState.VESSEL_SHIELD,
-			GameState.VESSEL_TRANSPORTER][i]
+	var definitions: Array = VESSEL_DEFINITIONS.all()
+	for i in range(mini(lab_vessel_buttons.size(), definitions.size())):
+		var definition: Resource = definitions[i]
+		var this_vessel: String = definition.definition_id
 		lab_vessel_buttons[i].enabled = true
-		lab_vessel_buttons[i].glow_color = _vessel_colour(this_vessel)
+		lab_vessel_buttons[i].icon = definition.icon
+		lab_vessel_buttons[i].glow_color = definition.glow_color
+		lab_vessel_labels[i].text = definition.display_name
 		lab_vessel_buttons[i].highlighted = this_vessel == lab_vessel
 		lab_vessel_buttons[i].queue_redraw()
-	lab_vessel_label.text = "%s research" % GameState.VESSEL_NAMES.get(lab_vessel, lab_vessel)
+	lab_vessel_label.text = "%s research" % GameState.vessel_name(lab_vessel)
 
 	var options: Array = _lab_options()
 	for i in range(lab_upgrade_buttons.size()):
@@ -820,7 +832,7 @@ func _refresh_lab() -> void:
 		if not visible:
 			continue
 		var option: Dictionary = options[i]
-		var price_text: String = "%d ore" % (GameState.UNLOCK_SHIELD_COST if bool(option.unlock) else GameState.upgrade_cost(option.id))
+		var price_text: String = "%d ore" % (int(option.cost) if bool(option.unlock) else GameState.upgrade_cost(option.id))
 		if not bool(option.unlock) and GameState.upgrade_maxed(option.id):
 			price_text = "MAX"
 		var level_note: String = "" if bool(option.unlock) else "  %d/%d" % [
@@ -848,29 +860,11 @@ func _refresh_lab() -> void:
 
 
 func _upgrade_icon(option: Dictionary) -> IconButton.Icon:
-	if bool(option.unlock):
-		return IconButton.Icon.UPGRADE_UNLOCK_SHIELD
-	match String(option.id):
-		"int_damage": return IconButton.Icon.UPGRADE_DAMAGE
-		"int_rate": return IconButton.Icon.UPGRADE_RATE
-		"int_range": return IconButton.Icon.UPGRADE_RANGE
-		"int_speed", "shd_speed": return IconButton.Icon.UPGRADE_THRUSTERS
-		"shd_hits": return IconButton.Icon.UPGRADE_SHIELD_HITS
-		"shd_recharge": return IconButton.Icon.UPGRADE_SHIELD_RECHARGE
-		"trn_capacity": return IconButton.Icon.UPGRADE_CARGO
-		"trn_speed": return IconButton.Icon.UPGRADE_ENGINES
-		_: return IconButton.Icon.SHIP_LAB
+	return int(option.get("icon", IconButton.Icon.SHIP_LAB))
 
 
 func _on_craft_shield() -> void:
-	if craft_building_id == 0:
-		_say("No crafter selected - reopen this panel from the building")
-		return
-	if not GameState.shield_vessel_unlocked():
-		_say("Shield vessels must be unlocked at a ship lab first")
-		return
-	GameState.queue_order(craft_building_id, GameState.VESSEL_SHIELD)
-	_report_order(GameState.VESSEL_SHIELD)
+	_on_craft_vessel(GameState.VESSEL_SHIELD)
 
 
 # --- moving ore, in both directions, at any building (#24) ----------------
@@ -957,8 +951,8 @@ func _refresh_queue() -> void:
 		if not slot.visible:
 			continue
 		var order: Dictionary = orders[i]
-		slot.icon = IconButton.Icon.TRANSPORT_HUB if order.product == GameState.PRODUCT_TRANSPORTER \
-			else IconButton.Icon.SHIP
+		var definition: Resource = VESSEL_DEFINITIONS.get_definition(String(order.product))
+		slot.icon = definition.icon
 		slot.glow_color = _vessel_colour(String(order.product))
 		# Only the one under construction reads as active; the rest are
 		# waiting, and greyed says so without needing a caption each.
@@ -971,29 +965,24 @@ func _refresh_queue() -> void:
 	var head: Dictionary = orders[0]
 	if bool(head.started):
 		queue_detail.text = "Building %s  %d%%\nTap to cancel" % [
-			GameState.VESSEL_NAMES.get(head.product, head.product),
+			GameState.vessel_name(String(head.product)),
 			int(round(float(head.progress) * 100.0)),
 		]
 	else:
 		queue_detail.text = "%s waiting for ore\nTap to cancel" % \
-			GameState.VESSEL_NAMES.get(head.product, head.product)
+			GameState.vessel_name(String(head.product))
 
 
 func _vessel_colour(product: String) -> Color:
-	match product:
-		GameState.VESSEL_SHIELD:
-			return Color(0.45, 0.8, 1.0)
-		GameState.PRODUCT_TRANSPORTER:
-			return Color(0.95, 0.55, 0.85)
-		_:
-			return Color(0.25, 0.85, 1.0)
+	var definition: Resource = VESSEL_DEFINITIONS.get_definition(product)
+	return definition.glow_color if definition != null else Color(0.25, 0.85, 1.0)
 
 
 func _on_queue_slot(index: int) -> void:
 	var orders: Array = GameState.order_list(craft_building_id)
 	if index >= orders.size():
 		return
-	var vessel: String = GameState.VESSEL_NAMES.get(orders[index].product, orders[index].product)
+	var vessel: String = GameState.vessel_name(String(orders[index].product))
 	var refunded: bool = bool(orders[index].started)
 	if not GameState.cancel_order(craft_building_id, index):
 		return
@@ -1018,12 +1007,12 @@ func _on_hangar_crew_type(index: int) -> void:
 		return
 	var stored_index: int = GameState.stored_vessels.find(type)
 	if stored_index < 0:
-		hangar_status.text = "No %s available" % GameState.VESSEL_NAMES.get(type, type)
+		hangar_status.text = "No %s available" % GameState.vessel_name(type)
 		return
 	if not fleet.add_ship(GameState.take_stored_vessel(stored_index)):
 		hangar_status.text = "Could not crew that vessel"
 		return
-	hangar_status.text = "%s joined the fleet" % GameState.VESSEL_NAMES.get(type, type)
+	hangar_status.text = "%s joined the fleet" % GameState.vessel_name(type)
 	_refresh_hangar()
 
 
@@ -1035,32 +1024,40 @@ func _on_hangar_store_type(index: int) -> void:
 			ship_index = i
 			break
 	if ship_index < 0:
-		hangar_status.text = "No %s in the fleet" % GameState.VESSEL_NAMES.get(type, type)
+		hangar_status.text = "No %s in the fleet" % GameState.vessel_name(type)
 		return
 	var stored: String = fleet.store_ship(ship_index)
 	if stored == "":
 		hangar_status.text = "Keep one ship deployed"
 		return
 	GameState.stored_vessels.append(stored)
-	hangar_status.text = "%s stored in the hangar" % GameState.VESSEL_NAMES.get(stored, stored)
+	hangar_status.text = "%s stored in the hangar" % GameState.vessel_name(stored)
 	_refresh_hangar()
 
 
 func _hangar_types() -> Array:
-	return [GameState.VESSEL_INTERCEPTOR, GameState.VESSEL_SHIELD, GameState.VESSEL_TRANSPORTER]
+	var types: Array = []
+	for definition in VESSEL_DEFINITIONS.all():
+		types.append(definition.definition_id)
+	return types
 
 
 func _refresh_hangar() -> void:
 	var types: Array = _hangar_types()
 	for i in range(types.size()):
 		var type: String = types[i]
+		var definition: Resource = VESSEL_DEFINITIONS.get_definition(type)
 		var available: int = GameState.stored_vessels.count(type)
 		var deployed: int = 0
 		for ship in fleet.ships:
 			if is_instance_valid(ship) and String(ship.vessel_type) == type:
 				deployed += 1
-		hangar_available_labels[i].text = "%s\n%d available" % [GameState.VESSEL_NAMES.get(type, type), available]
-		hangar_fleet_labels[i].text = "%s\n%d in fleet" % [GameState.VESSEL_NAMES.get(type, type), deployed]
+		hangar_available_labels[i].text = "%s\n%d available" % [definition.display_name, available]
+		hangar_fleet_labels[i].text = "%s\n%d in fleet" % [definition.display_name, deployed]
+		hangar_available_slots[i].icon = definition.icon
+		hangar_fleet_slots[i].icon = definition.icon
+		hangar_available_slots[i].glow_color = definition.glow_color
+		hangar_fleet_slots[i].glow_color = definition.glow_color
 		hangar_available_slots[i].enabled = available > 0 and fleet.ships.size() < GameState.max_fleet_size()
 		hangar_fleet_slots[i].enabled = deployed > 0 and fleet.ships.size() > 1
 		hangar_available_slots[i].queue_redraw()
diff --git a/GameState.gd b/GameState.gd
index 56f773f..37d110a 100644
--- a/GameState.gd
+++ b/GameState.gd
@@ -3,6 +3,7 @@ extends Node
 const INVENTORY = preload("res://Inventory.gd")
 const RESOURCE_DEFINITIONS = preload("res://ResourceDefinitions.gd")
 const BUILDING_DEFINITIONS = preload("res://BuildingDefinitions.gd")
+const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")
 
 
 # Autoload singleton - the one thing that survives change_scene_to_file()
@@ -404,21 +405,10 @@ const VESSEL_INTERCEPTOR: String = "interceptor"
 const VESSEL_SHIELD: String = "shield"
 const VESSEL_TRANSPORTER: String = "transporter"
 
-const VESSEL_NAMES: Dictionary = {
-	VESSEL_INTERCEPTOR: "Interceptor",
-	VESSEL_SHIELD: "Shield Vessel",
-	VESSEL_TRANSPORTER: "Transporter",
-}
-
+# Compatibility constants for callers and old tests. Runtime metadata is
+# resolved from VesselDefinition below.
 const SHIELD_COST: int = 14
-
-# How long one vessel takes to build, once its ore is actually in the
-# building. A queue you can watch and cancel needs time to exist in.
-const BUILD_TIMES: Dictionary = {
-	VESSEL_INTERCEPTOR: 10.0,
-	VESSEL_SHIELD: 16.0,
-	VESSEL_TRANSPORTER: 8.0,
-}
+const TRANSPORTER_COST: int = 10
 const LAB_RESEARCH_TIME: float = 8.0
 
 
@@ -429,57 +419,14 @@ var build_time_scale: float = 1.0
 
 
 func build_time(product: String) -> float:
-	return float(BUILD_TIMES.get(product, 10.0)) * build_time_scale
+	var definition: Resource = VESSEL_DEFINITIONS.get_definition(product)
+	return (definition.build_time if definition != null else 10.0) * build_time_scale
 
 
 func lab_research_time() -> float:
 	return LAB_RESEARCH_TIME * build_time_scale
 
-# Researched at the ship lab, per vessel type. Separate from SKILL_TREE on
-# purpose: that gates what the player may build at all and is a strategic
-# spine, while these are repeatable tuning on a vessel you already have.
-# `cost` is the FIRST level; each level after costs cost * (level + 1), so
-# the third point in something is not the same price as the first.
-const VESSEL_UPGRADES: Array = [
-	{
-		"id": "int_damage", "vessel": VESSEL_INTERCEPTOR, "name": "Heavy Slugs",
-		"cost": 30, "max_level": 3, "desc": "+1 damage per shot.",
-	},
-	{
-		"id": "int_rate", "vessel": VESSEL_INTERCEPTOR, "name": "Autoloader",
-		"cost": 25, "max_level": 3, "desc": "Fires 15% faster per level.",
-	},
-	{
-		"id": "int_range", "vessel": VESSEL_INTERCEPTOR, "name": "Targeting Array",
-		"cost": 20, "max_level": 3, "desc": "+60 firing range per level.",
-	},
-	{
-		"id": "int_speed", "vessel": VESSEL_INTERCEPTOR, "name": "Thrusters",
-		"cost": 25, "max_level": 3, "desc": "+40 top speed, +60 acceleration per level.",
-	},
-	{
-		"id": "shd_hits", "vessel": VESSEL_SHIELD, "name": "Layered Emitters",
-		"cost": 60, "max_level": 2, "desc": "+1 hit absorbed before the shield drops.",
-	},
-	{
-		"id": "shd_recharge", "vessel": VESSEL_SHIELD, "name": "Fast Cycling",
-		"cost": 35, "max_level": 3, "desc": "Shield returns 1.2s sooner per level.",
-	},
-	{
-		"id": "shd_speed", "vessel": VESSEL_SHIELD, "name": "Thrusters",
-		"cost": 25, "max_level": 3, "desc": "+40 top speed, +60 acceleration per level.",
-	},
-	{
-		"id": "trn_capacity", "vessel": VESSEL_TRANSPORTER, "name": "Expanded Hold",
-		"cost": 30, "max_level": 3, "desc": "Carries 8 more ore per supply run.",
-	},
-	{
-		"id": "trn_speed", "vessel": VESSEL_TRANSPORTER, "name": "Freight Engines",
-		"cost": 30, "max_level": 3, "desc": "+70 speed on supply runs.",
-	},
-]
-
-# Base figures every vessel starts from, before anything is researched.
+# Compatibility constants. VesselDefinition owns the live base figures.
 const SHIP_BASE_DAMAGE: int = 1
 const SHIP_BASE_COOLDOWN: float = 0.5
 const SHIP_BASE_RANGE: float = 320.0
@@ -503,9 +450,7 @@ func has_ship_lab() -> bool:
 
 
 func shield_vessel_unlocked() -> bool:
-	# Unlocked AT the lab, by paying for it there - a vessel type rather than
-	# a stat, so it is a one-off rather than a level.
-	return int(vessel_levels.get(UNLOCK_SHIELD_VESSEL, 0)) > 0
+	return vessel_is_unlocked(VESSEL_SHIELD)
 
 
 const UNLOCK_SHIELD_VESSEL: String = "unlock_shield"
@@ -513,27 +458,69 @@ const UNLOCK_SHIELD_COST: int = 45
 
 
 func unlock_shield_vessel() -> bool:
-	if shield_vessel_unlocked() or not has_ship_lab():
+	return unlock_vessel(VESSEL_SHIELD)
+
+
+func vessel_definition(vessel: String) -> Resource:
+	return VESSEL_DEFINITIONS.get_definition(vessel)
+
+
+func vessel_name(vessel: String) -> String:
+	var definition: Resource = vessel_definition(vessel)
+	return definition.display_name if definition != null else vessel.capitalize()
+
+
+func vessel_has_capability(vessel: String, capability: String) -> bool:
+	var definition: Resource = vessel_definition(vessel)
+	return definition != null and definition.has_capability(capability)
+
+
+func vessel_is_unlocked(vessel: String) -> bool:
+	var definition: Resource = vessel_definition(vessel)
+	if definition == null:
 		return false
-	if not spend(UNLOCK_SHIELD_COST):
+	return definition.unlock_id == "" or int(vessel_levels.get(definition.unlock_id, 0)) > 0
+
+
+func vessel_for_unlock(unlock_id: String) -> Resource:
+	for definition in VESSEL_DEFINITIONS.all():
+		if definition.unlock_id == unlock_id:
+			return definition
+	return null
+
+
+func unlock_vessel(vessel: String) -> bool:
+	var definition: Resource = vessel_definition(vessel)
+	if definition == null or definition.unlock_id == "" or vessel_is_unlocked(vessel) or not has_ship_lab():
 		return false
-	vessel_levels[UNLOCK_SHIELD_VESSEL] = 1
-	vessel_upgraded.emit(UNLOCK_SHIELD_VESSEL)
+	if not spend(definition.unlock_cost):
+		return false
+	vessel_levels[definition.unlock_id] = 1
+	vessel_upgraded.emit(definition.unlock_id)
 	return true
 
 
 func upgrade_def(id: String) -> Dictionary:
-	for u in VESSEL_UPGRADES:
-		if u.id == id:
-			return u
+	for definition in VESSEL_DEFINITIONS.all():
+		for upgrade in definition.upgrades:
+			if upgrade.upgrade_id == id:
+				return {"id": upgrade.upgrade_id, "vessel": definition.definition_id,
+					"name": upgrade.display_name, "desc": upgrade.description,
+					"cost": upgrade.base_cost, "max_level": upgrade.max_level,
+					"icon": upgrade.icon, "resource": upgrade}
 	return {}
 
 
 func upgrades_for(vessel: String) -> Array:
 	var out: Array = []
-	for u in VESSEL_UPGRADES:
-		if u.vessel == vessel:
-			out.append(u)
+	var definition: Resource = vessel_definition(vessel)
+	if definition == null:
+		return out
+	for upgrade in definition.upgrades:
+		out.append({"id": upgrade.upgrade_id, "vessel": vessel,
+			"name": upgrade.display_name, "desc": upgrade.description,
+			"cost": upgrade.base_cost, "max_level": upgrade.max_level,
+			"icon": upgrade.icon, "resource": upgrade})
 	return out
 
 
@@ -567,66 +554,51 @@ func buy_upgrade(id: String) -> bool:
 	return true
 
 
-# --- what those upgrades actually come to ---------------------------------
-# Read live rather than baked into a vessel when it is built, so researching
-# something improves the ships already flying instead of only the next ones.
-
-func ship_damage(vessel: String) -> int:
-	return SHIP_BASE_DAMAGE + (upgrade_level("int_damage") if vessel == VESSEL_INTERCEPTOR else 0)
+func vessel_stat(vessel: String, stat: String) -> float:
+	var definition: Resource = vessel_definition(vessel)
+	if definition == null:
+		return 0.0
+	var value: float = float(definition.base_stats.get(stat, 0.0))
+	for upgrade in definition.upgrades:
+		var level: int = upgrade_level(upgrade.upgrade_id)
+		value += float(upgrade.additive_modifiers.get(stat, 0.0)) * level
+		if upgrade.multiplicative_modifiers.has(stat):
+			value *= pow(float(upgrade.multiplicative_modifiers[stat]), level)
+	if definition.minimum_stats.has(stat):
+		value = maxf(value, float(definition.minimum_stats[stat]))
+	return value
 
 
-func ship_fire_cooldown(vessel: String) -> float:
-	if vessel != VESSEL_INTERCEPTOR:
-		return SHIP_BASE_COOLDOWN
-	return SHIP_BASE_COOLDOWN * pow(0.85, float(upgrade_level("int_rate")))
-
-
-func ship_fire_range(vessel: String) -> float:
-	return SHIP_BASE_RANGE + (60.0 * upgrade_level("int_range") if vessel == VESSEL_INTERCEPTOR else 0.0)
-
-
-func _speed_levels(vessel: String) -> int:
-	if vessel == VESSEL_SHIELD:
-		return upgrade_level("shd_speed")
-	return upgrade_level("int_speed")
-
-
-func ship_max_speed(vessel: String) -> float:
-	return SHIP_BASE_SPEED + 40.0 * _speed_levels(vessel)
-
-
-func ship_acceleration(vessel: String) -> float:
-	return SHIP_BASE_ACCEL + 60.0 * _speed_levels(vessel)
-
+func ship_damage(vessel: String) -> int: return int(vessel_stat(vessel, "damage"))
+func ship_fire_cooldown(vessel: String) -> float: return vessel_stat(vessel, "fire_cooldown")
+func ship_fire_range(vessel: String) -> float: return vessel_stat(vessel, "fire_range")
+func ship_max_speed(vessel: String) -> float: return vessel_stat(vessel, "max_speed")
+func ship_acceleration(vessel: String) -> float: return vessel_stat(vessel, "acceleration")
 
 func shield_max_charges() -> int:
-	return SHIELD_BASE_CHARGES + upgrade_level("shd_hits")
-
+	var definition: Resource = VESSEL_DEFINITIONS.with_capability("shield")
+	return int(vessel_stat(definition.definition_id, "shield_charges"))
 
 func shield_recharge_time() -> float:
-	return maxf(2.0, SHIELD_BASE_RECHARGE - 1.2 * upgrade_level("shd_recharge"))
-
+	var definition: Resource = VESSEL_DEFINITIONS.with_capability("shield")
+	return vessel_stat(definition.definition_id, "shield_recharge")
 
 func transporter_load_limit() -> int:
-	return TRANSPORTER_BASE_LOAD + 8 * upgrade_level("trn_capacity")
-
+	var definition: Resource = VESSEL_DEFINITIONS.with_capability("transport")
+	return int(vessel_stat(definition.definition_id, "cargo_capacity"))
 
 func transporter_speed() -> float:
-	return TRANSPORTER_BASE_SPEED + 70.0 * upgrade_level("trn_speed")
+	var definition: Resource = VESSEL_DEFINITIONS.with_capability("transport")
+	return vessel_stat(definition.definition_id, "transport_speed")
 
 
 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
-	if product == VESSEL_SHIELD:
-		return SHIELD_COST
-	return SHIP_COST
+	var definition: Resource = vessel_definition(product)
+	return definition.build_cost if definition != null else 0
 
 
 func can_produce(type: String) -> bool:
@@ -713,13 +685,14 @@ func queue_order(id: int, product: String = PRODUCT_SHIP) -> bool:
 	var b: Dictionary = find_building(id)
 	if b.is_empty() or not can_produce(b.type):
 		return false
-	if product == VESSEL_SHIELD and not shield_vessel_unlocked():
+	var definition: Resource = vessel_definition(product)
+	if definition == null or not vessel_is_unlocked(product):
 		return false
-	if product == PRODUCT_TRANSPORTER and not has_transport_hub():
+	if definition.has_capability("transport") 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
-	if product == PRODUCT_TRANSPORTER and not can_station_transporter():
+	if definition.has_capability("transport") and not can_station_transporter():
 		# Every berth is taken or spoken for (#20).
 		return false
 	(b.orders as Array).append({"product": product, "elapsed": 0.0, "started": false})
@@ -742,15 +715,16 @@ func _advance_production(delta: float) -> void:
 		var product: String = String(order.product)
 		var cost: int = product_cost(product)
 		var inventory: RefCounted = _inventory_for_record(b)
+		var definition: Resource = vessel_definition(product)
 
 		if not bool(order.started):
 			if inventory.amount(RESOURCE_ORE) < cost:
 				continue
-			if product == PRODUCT_TRANSPORTER and transporters.size() >= transport_capacity():
+			if definition.has_capability("transport") and transporters.size() >= transport_capacity():
 				# A hub was demolished after this was ordered, so the berth it
 				# was going to use is gone. Hold rather than overfill.
 				continue
-			if product == PRODUCT_TRANSPORTER and nearest_hub_to(b.position).is_empty():
+			if definition.has_capability("transport") and nearest_hub_to(b.position).is_empty():
 				continue
 			inventory.withdraw(RESOURCE_ORE, cost)
 			order.started = true
@@ -760,7 +734,7 @@ func _advance_production(delta: float) -> void:
 			continue
 
 		orders.pop_front()
-		if product == PRODUCT_TRANSPORTER:
+		if definition.has_capability("transport"):
 			# Transporters are unchanged: they take themselves to the nearest
 			# hub and wait for work (#19).
 			_station_transporter(b.position)
@@ -782,7 +756,8 @@ func queue_lab_research(lab_id: int, upgrade_id: String) -> bool:
 	if not building_has_capability(lab, "vessel_research") or upgrade_id == "":
 		return false
 	var orders: Array = lab.get("research_orders", [])
-	if not orders.is_empty() or (upgrade_id != UNLOCK_SHIELD_VESSEL and upgrade_maxed(upgrade_id)):
+	var unlock_definition: Resource = vessel_for_unlock(upgrade_id)
+	if not orders.is_empty() or (unlock_definition == null and upgrade_maxed(upgrade_id)):
 		return false
 	orders.append({"id": upgrade_id, "elapsed": 0.0, "started": false})
 	lab.research_orders = orders
@@ -804,7 +779,8 @@ func _advance_lab_research(delta: float) -> void:
 			continue
 		var order: Dictionary = orders[0]
 		var id: String = String(order.id)
-		var cost: int = UNLOCK_SHIELD_COST if id == UNLOCK_SHIELD_VESSEL else upgrade_cost(id)
+		var unlock_definition: Resource = vessel_for_unlock(id)
+		var cost: int = unlock_definition.unlock_cost if unlock_definition != null else upgrade_cost(id)
 		var inventory: RefCounted = _inventory_for_record(lab)
 		if not bool(order.started):
 			if inventory.amount(RESOURCE_ORE) < cost:
@@ -814,7 +790,7 @@ func _advance_lab_research(delta: float) -> void:
 		order.elapsed = float(order.elapsed) + delta
 		if float(order.elapsed) < lab_research_time():
 			continue
-		if id == UNLOCK_SHIELD_VESSEL:
+		if unlock_definition != null:
 			vessel_levels[id] = 1
 		else:
 			vessel_levels[id] = upgrade_level(id) + 1
@@ -1041,7 +1017,7 @@ func pending_transporter_orders() -> int:
 	var n: int = 0
 	for b in buildings:
 		for o in b.get("orders", []):
-			if String(o.product) == PRODUCT_TRANSPORTER:
+			if vessel_has_capability(String(o.product), "transport"):
 				n += 1
 	return n
 
diff --git a/InterceptorDamageUpgrade.tres b/InterceptorDamageUpgrade.tres
new file mode 100644
index 0000000..835851a
--- /dev/null
+++ b/InterceptorDamageUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "int_damage"
+display_name = "Heavy Slugs"
+description = "+1 damage per shot."
+base_cost = 30
+max_level = 3
+icon = 15
+additive_modifiers = {"damage": 1.0}
diff --git a/InterceptorRangeUpgrade.tres b/InterceptorRangeUpgrade.tres
new file mode 100644
index 0000000..ce01efe
--- /dev/null
+++ b/InterceptorRangeUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "int_range"
+display_name = "Targeting Array"
+description = "+60 firing range per level."
+base_cost = 20
+max_level = 3
+icon = 17
+additive_modifiers = {"fire_range": 60.0}
diff --git a/InterceptorRateUpgrade.tres b/InterceptorRateUpgrade.tres
new file mode 100644
index 0000000..4add45e
--- /dev/null
+++ b/InterceptorRateUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "int_rate"
+display_name = "Autoloader"
+description = "Fires 15% faster per level."
+base_cost = 25
+max_level = 3
+icon = 16
+multiplicative_modifiers = {"fire_cooldown": 0.85}
diff --git a/InterceptorSpeedUpgrade.tres b/InterceptorSpeedUpgrade.tres
new file mode 100644
index 0000000..5549971
--- /dev/null
+++ b/InterceptorSpeedUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "int_speed"
+display_name = "Thrusters"
+description = "+40 top speed, +60 acceleration per level."
+base_cost = 25
+max_level = 3
+icon = 18
+additive_modifiers = {"max_speed": 40.0, "acceleration": 60.0}
diff --git a/InterceptorVesselDefinition.tres b/InterceptorVesselDefinition.tres
new file mode 100644
index 0000000..a18f6c4
--- /dev/null
+++ b/InterceptorVesselDefinition.tres
@@ -0,0 +1,20 @@
+[gd_resource type="Resource" script_class="VesselDefinition" load_steps=7 format=3]
+[ext_resource type="Script" path="res://VesselDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://VesselWeaponComponent.tscn" id="2"]
+[ext_resource type="Resource" path="res://InterceptorDamageUpgrade.tres" id="3"]
+[ext_resource type="Resource" path="res://InterceptorRateUpgrade.tres" id="4"]
+[ext_resource type="Resource" path="res://InterceptorRangeUpgrade.tres" id="5"]
+[ext_resource type="Resource" path="res://InterceptorSpeedUpgrade.tres" id="6"]
+[resource]
+script = ExtResource("1")
+definition_id = "interceptor"
+display_name = "Interceptor"
+description = "Fast combat vessel with a rapid-firing cannon."
+build_cost = 6
+build_time = 10.0
+icon = 2
+glow_color = Color(0.25, 0.85, 1, 1)
+capabilities = PackedStringArray("weapon")
+component_scenes = Array[PackedScene]([ExtResource("2")])
+base_stats = {"damage": 1.0, "fire_cooldown": 0.5, "fire_range": 320.0, "max_speed": 460.0, "acceleration": 450.0}
+upgrades = Array[Resource]([ExtResource("3"), ExtResource("4"), ExtResource("5"), ExtResource("6")])
diff --git a/ShieldHitsUpgrade.tres b/ShieldHitsUpgrade.tres
new file mode 100644
index 0000000..2530597
--- /dev/null
+++ b/ShieldHitsUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "shd_hits"
+display_name = "Layered Emitters"
+description = "+1 hit absorbed before the shield drops."
+base_cost = 60
+max_level = 2
+icon = 19
+additive_modifiers = {"shield_charges": 1.0}
diff --git a/ShieldRechargeUpgrade.tres b/ShieldRechargeUpgrade.tres
new file mode 100644
index 0000000..d73cf09
--- /dev/null
+++ b/ShieldRechargeUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "shd_recharge"
+display_name = "Fast Cycling"
+description = "Shield returns 1.2s sooner per level."
+base_cost = 35
+max_level = 3
+icon = 20
+additive_modifiers = {"shield_recharge": -1.2}
diff --git a/ShieldSpeedUpgrade.tres b/ShieldSpeedUpgrade.tres
new file mode 100644
index 0000000..fe5a4b6
--- /dev/null
+++ b/ShieldSpeedUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "shd_speed"
+display_name = "Thrusters"
+description = "+40 top speed, +60 acceleration per level."
+base_cost = 25
+max_level = 3
+icon = 18
+additive_modifiers = {"max_speed": 40.0, "acceleration": 60.0}
diff --git a/ShieldVesselDefinition.tres b/ShieldVesselDefinition.tres
new file mode 100644
index 0000000..9df3bf8
--- /dev/null
+++ b/ShieldVesselDefinition.tres
@@ -0,0 +1,25 @@
+[gd_resource type="Resource" script_class="VesselDefinition" load_steps=7 format=3]
+[ext_resource type="Script" path="res://VesselDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://VesselWeaponComponent.tscn" id="2"]
+[ext_resource type="PackedScene" path="res://VesselShieldComponent.tscn" id="3"]
+[ext_resource type="Resource" path="res://ShieldHitsUpgrade.tres" id="4"]
+[ext_resource type="Resource" path="res://ShieldRechargeUpgrade.tres" id="5"]
+[ext_resource type="Resource" path="res://ShieldSpeedUpgrade.tres" id="6"]
+[resource]
+script = ExtResource("1")
+definition_id = "shield"
+display_name = "Shield Vessel"
+description = "Combat vessel whose rechargeable personal shield absorbs lethal impacts."
+build_cost = 14
+build_time = 16.0
+icon = 2
+glow_color = Color(0.45, 0.8, 1, 1)
+capabilities = PackedStringArray("weapon", "shield")
+component_scenes = Array[PackedScene]([ExtResource("2"), ExtResource("3")])
+base_stats = {"damage": 1.0, "fire_cooldown": 0.5, "fire_range": 320.0, "max_speed": 460.0, "acceleration": 450.0, "shield_charges": 1.0, "shield_recharge": 6.0}
+minimum_stats = {"shield_recharge": 2.0}
+upgrades = Array[Resource]([ExtResource("4"), ExtResource("5"), ExtResource("6")])
+unlock_id = "unlock_shield"
+unlock_name = "Unlock Shield Vessel"
+unlock_description = "Lets the ship crafter build shield vessels. Its shield absorbs one lethal hit, then cycles back up."
+unlock_cost = 45
diff --git a/Ship.gd b/Ship.gd
index 624c312..1c2727c 100644
--- a/Ship.gd
+++ b/Ship.gd
@@ -2,224 +2,134 @@ extends Area2D
 
 signal destroyed
 
-# Deliberately faster than Fleet.cruise_speed: the fleet as a whole travels
-# at the cruise rate, and this headroom is what lets an individual ship
-# close on its formation slot - so a pivot mid-flight resolves quickly
-# instead of the ship having no speed budget left over for it.
+const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")
+
 @export var max_speed: float = 460.0
 @export var acceleration: float = 450.0
 @export var rotation_speed: float = 8.0
 @export var arrive_radius: float = 6.0
-
-@export var fire_range: float = 320.0
-@export var fire_cooldown: float = 0.5
-# How long to wait before looking for targets again after finding none.
-@export var idle_rescan_interval: float = 0.25
-@export var projectile_damage: int = 1
-
-# Which kind of vessel this is (GameState.VESSEL_*). Drives both its
-# researched statistics and whether it carries a shield (#5).
 @export var vessel_type: String = "interceptor"
 
-# --- shield (#5) ----------------------------------------------------------
-const SHIELD_COLOR: Color = Color(0.45, 0.8, 1.0)
-const SHIELD_RADIUS: float = 30.0
-
-# A shield vessel survives a hit that would destroy any other ship, and is
-# then defenceless until it cycles back up. Personal, not a bubble: it
-# protects the vessel carrying it and nothing else.
-var shield_charges: int = 0
-var shield_recharge_left: float = 0.0
-var _shield_ring: Node2D = null
-
-# Neon colours, assigned by Fleet on spawn so a scene can tint its fleet.
-# The lunar surface is a bright grey, where the default near-white core all
-# but vanishes - PlanetSurface.tscn passes a dark core there. See NeonDraw.
+var definition: Resource
 var glow_color: Color = Color(0.25, 0.85, 1.0)
-var core_color: Color = Color(1.0, 1.0, 1.0)
-
+var core_color: Color = Color.WHITE
 var velocity: Vector2 = Vector2.ZERO
-# The fleet's own velocity, supplied by Fleet as CONTEXT rather than as a
-# facing command - the ship works out where to point from it.
-#
-# It is needed because `velocity` below is not the ship's true motion while
-# it is holding formation: the slot it chases sits inside arrive_radius, so
-# the ship snaps onto it and reports zero velocity even though it is being
-# carried along at cruise speed. Facing derived from `velocity` alone
-# therefore froze at whatever heading the ship last happened to travel.
-# Adding the two gives the ship's ACTUAL motion through the world, which is
-# the honest thing to point along in every case: it equals the fleet's
-# heading when station-keeping, the ship's own heading when manoeuvring
-# alone, and the true blend of both while strafing into a new slot.
 var fleet_velocity: Vector2 = Vector2.ZERO
 var move_target: Vector2
-var fire_timer: float = 0.0
-var projectile_scene: PackedScene = preload("res://Projectile.tscn")
+
+# Compatibility accessors keep old saves/tests readable while shield state
+# itself belongs exclusively to the optional ShieldComponent.
+var shield_charges: int:
+	get:
+		var component: Node = get_component("shield")
+		return component.charges if component != null else 0
+	set(value):
+		var component: Node = get_component("shield")
+		if component != null:
+			component.set_charges(value)
+
+var shield_recharge_left: float:
+	get:
+		var component: Node = get_component("shield")
+		return component.recharge_left if component != null else 0.0
+	set(value):
+		var component: Node = get_component("shield")
+		if component != null:
+			component.recharge_left = value
+
+var projectile_damage: int:
+	get:
+		var component: Node = get_component("weapon")
+		return component.projectile_damage if component != null else 0
 
 
 func _ready() -> void:
 	move_target = position
 	add_to_group("player_ships")
 	area_entered.connect(_on_area_entered)
-	if vessel_type == GameState.VESSEL_SHIELD:
-		_build_shield_ring()
-		shield_charges = GameState.shield_max_charges()
+	definition = VESSEL_DEFINITIONS.get_definition(vessel_type)
+	if definition == null:
+		return
+	glow_color = definition.glow_color
+	for component_scene in definition.component_scenes:
+		var component: Node = component_scene.instantiate()
+		add_child(component)
+		if component.has_method("setup"):
+			component.setup()
 	apply_vessel_stats()
 	queue_redraw()
 
 
+func get_component(capability: String) -> Node:
+	for child in get_children():
+		if child.get("capability_id") == capability:
+			return child
+	return null
+
+
+func has_capability(capability: String) -> bool:
+	return get_component(capability) != null
+
+
 func set_move_target(world_pos: Vector2) -> void:
 	move_target = world_pos
 
 
 func apply_vessel_stats() -> void:
-	# Read from GameState rather than baked in at spawn, so researching an
-	# upgrade improves the ships already flying and not just the next one
-	# built. Fleet calls this on every vessel when something is bought.
-	max_speed = GameState.ship_max_speed(vessel_type)
-	acceleration = GameState.ship_acceleration(vessel_type)
-	fire_range = GameState.ship_fire_range(vessel_type)
-	fire_cooldown = GameState.ship_fire_cooldown(vessel_type)
-	projectile_damage = GameState.ship_damage(vessel_type)
-	if vessel_type == GameState.VESSEL_SHIELD:
-		# Topping up a live shield with researched capacity, without
-		# refilling one that is currently down and cycling.
-		var was_up: bool = shield_charges > 0
-		shield_charges = GameState.shield_max_charges() if was_up else shield_charges
-	_update_shield_visual()
+	if definition == null:
+		definition = VESSEL_DEFINITIONS.get_definition(vessel_type)
+	if definition == null:
+		return
+	max_speed = GameState.vessel_stat(vessel_type, "max_speed")
+	acceleration = GameState.vessel_stat(vessel_type, "acceleration")
+	for child in get_children():
+		if child.has_method("apply_stats"):
+			child.apply_stats()
 
 
 func has_shield() -> bool:
-	return vessel_type == GameState.VESSEL_SHIELD and shield_charges > 0
-
-
-func _update_shield_visual() -> void:
-	if _shield_ring == null:
-		return
-	# visible only - per #10 the ring is rasterised once and never redrawn to
-	# turn it on and off.
-	_shield_ring.visible = has_shield()
-
-
-func _tick_shield(delta: float) -> void:
-	if vessel_type != GameState.VESSEL_SHIELD:
-		return
-	if shield_charges >= GameState.shield_max_charges():
-		return
-	shield_recharge_left -= delta
-	if shield_recharge_left <= 0.0:
-		shield_charges += 1
-		shield_recharge_left = GameState.shield_recharge_time()
-		_update_shield_visual()
+	var component: Node = get_component("shield")
+	return component != null and component.is_active()
 
 
 func _physics_process(delta: float) -> void:
-	_tick_shield(delta)
+	for child in get_children():
+		if child.has_method("tick"):
+			child.tick(delta)
+
 	var to_target: Vector2 = move_target - position
 	var distance: float = to_target.length()
-
 	if distance <= arrive_radius:
-		# Snap and stop dead - prevents residual float-level jitter that
-		# would otherwise keep nudging back and forth around the target.
 		position = move_target
 		velocity = Vector2.ZERO
 	else:
-		# Braking-distance formula: the fastest speed we can be going right
-		# now and still be able to decelerate to 0 exactly at the target,
-		# given our acceleration. Without this the ship approaches at full
-		# speed, overshoots (stopping distance = max_speed^2 / (2*accel)),
-		# and oscillates back and forth forever instead of settling.
 		var braking_speed: float = sqrt(2.0 * acceleration * distance)
 		var desired_speed: float = min(max_speed, braking_speed)
 		var desired_velocity: Vector2 = to_target.normalized() * desired_speed
 		velocity = velocity.move_toward(desired_velocity, acceleration * delta)
 		position += velocity * delta
 
-	# One owner, one rule: face the way this ship is actually travelling.
 	var motion: Vector2 = velocity + fleet_velocity
 	if motion.length() > 8.0:
 		var target_angle: float = motion.angle() + PI / 2.0
 		rotation = lerp_angle(rotation, target_angle, rotation_speed * delta)
 
-	_update_weapon(delta)
-
-
-func _update_weapon(delta: float) -> void:
-	fire_timer -= delta
-	if fire_timer > 0.0:
-		return
-
-	var target: Node2D = _find_nearest_enemy()
-	if target == null:
-		# Back off before scanning again. Without this, fire_timer stays at
-		# or below zero and every ship queries the whole "enemies" group and
-		# loops it on EVERY physics frame whenever nothing is in range -
-		# which is most of the time.
-		fire_timer = idle_rescan_interval
-		return
-
-	fire_timer = fire_cooldown
-	var proj: Node2D = projectile_scene.instantiate()
-	proj.position = position
-	proj.damage = projectile_damage
-	get_tree().root.add_child(proj)
-	proj.launch(target.position - position)
-
-
-func _find_nearest_enemy() -> Node2D:
-	var enemies: Array = get_tree().get_nodes_in_group("enemies")
-	var nearest: Node2D = null
-	var best_dist: float = fire_range
-
-	for e in enemies:
-		if not is_instance_valid(e):
-			continue
-		var d: float = position.distance_to(e.position)
-		if d <= best_dist:
-			best_dist = d
-			nearest = e
-
-	return nearest
-
 
 func _on_area_entered(area: Area2D) -> void:
 	if not (area.is_in_group("enemies") or area.is_in_group("asteroids")):
 		return
-	if has_shield():
-		# Absorbed. The thing that hit it is still destroyed - a shield stops
-		# the vessel dying, it does not make the rock harmless - but the
-		# vessel survives and is defenceless until the shield cycles back.
-		shield_charges -= 1
-		shield_recharge_left = GameState.shield_recharge_time()
-		_update_shield_visual()
-		if area.is_in_group("asteroids") and is_instance_valid(area):
-			area.queue_free()
-		return
+	for child in get_children():
+		if child.has_method("absorb_hit") and child.absorb_hit():
+			if area.is_in_group("asteroids") and is_instance_valid(area):
+				area.queue_free()
+			return
 	ShipExplosionVFX.spawn(get_tree().root, position)
 	destroyed.emit()
 	queue_free()
 
 
-func _build_shield_ring() -> void:
-	# Its own child, drawn once, toggled with `visible` (#10). A shield that
-	# came and went by redrawing the ship would re-tessellate the hull every
-	# time it cycled.
-	_shield_ring = NeonPiece.create(self, Vector2.ZERO, SHIELD_COLOR)
-	var points: PackedVector2Array = PackedVector2Array()
-	for i in range(14):
-		var a: float = (float(i) / 14.0) * TAU
-		points.append(Vector2(cos(a), sin(a)) * SHIELD_RADIUS)
-	_shield_ring.add_polygon(points, 0.7)
-	_shield_ring.queue_redraw()
-	_shield_ring.visible = false
-
-
 func _draw() -> void:
-	var nose: Vector2 = Vector2(0, -22)
-	var left: Vector2 = Vector2(-14, 16)
-	var right: Vector2 = Vector2(14, 16)
-	var points: PackedVector2Array = PackedVector2Array([nose, left, right])
-	# Constant glow, drawn once. No pulse means nothing changes frame to
-	# frame, so the ship never needs redrawing after _ready() - which also
-	# removes four antialiased polyline rebuilds per ship per frame.
+	var points: PackedVector2Array = definition.hull_points if definition != null else PackedVector2Array([
+		Vector2(0, -22), Vector2(-14, 16), Vector2(14, 16),
+	])
 	NeonDraw.draw_glowing_polygon(self, points, glow_color, 1.0, core_color)
diff --git a/TransportCapacityUpgrade.tres b/TransportCapacityUpgrade.tres
new file mode 100644
index 0000000..2c2b920
--- /dev/null
+++ b/TransportCapacityUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "trn_capacity"
+display_name = "Expanded Hold"
+description = "Carries 8 more resources per supply run."
+base_cost = 30
+max_level = 3
+icon = 21
+additive_modifiers = {"cargo_capacity": 8.0}
diff --git a/TransportSpeedUpgrade.tres b/TransportSpeedUpgrade.tres
new file mode 100644
index 0000000..43c3c96
--- /dev/null
+++ b/TransportSpeedUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "trn_speed"
+display_name = "Freight Engines"
+description = "+70 speed on supply runs."
+base_cost = 30
+max_level = 3
+icon = 22
+additive_modifiers = {"transport_speed": 70.0}
diff --git a/TransporterVesselDefinition.tres b/TransporterVesselDefinition.tres
new file mode 100644
index 0000000..c654a48
--- /dev/null
+++ b/TransporterVesselDefinition.tres
@@ -0,0 +1,19 @@
+[gd_resource type="Resource" script_class="VesselDefinition" load_steps=6 format=3]
+[ext_resource type="Script" path="res://VesselDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://VesselCargoComponent.tscn" id="2"]
+[ext_resource type="PackedScene" path="res://VesselTransportComponent.tscn" id="3"]
+[ext_resource type="Resource" path="res://TransportCapacityUpgrade.tres" id="4"]
+[ext_resource type="Resource" path="res://TransportSpeedUpgrade.tres" id="5"]
+[resource]
+script = ExtResource("1")
+definition_id = "transporter"
+display_name = "Transporter"
+description = "Unarmed cargo vessel stationed at a transport hub to move resources."
+build_cost = 10
+build_time = 8.0
+icon = 12
+glow_color = Color(0.95, 0.55, 0.85, 1)
+capabilities = PackedStringArray("cargo", "transport")
+component_scenes = Array[PackedScene]([ExtResource("2"), ExtResource("3")])
+base_stats = {"max_speed": 460.0, "acceleration": 450.0, "cargo_capacity": 20.0, "transport_speed": 340.0}
+upgrades = Array[Resource]([ExtResource("4"), ExtResource("5")])
diff --git a/VesselCargoComponent.gd b/VesselCargoComponent.gd
new file mode 100644
index 0000000..4373500
--- /dev/null
+++ b/VesselCargoComponent.gd
@@ -0,0 +1,9 @@
+class_name VesselCargoComponent
+extends Node
+
+var capability_id: String = "cargo"
+var capacity: int
+
+func apply_stats() -> void:
+	var state: Node = get_tree().root.get_node("GameState")
+	capacity = int(state.vessel_stat(get_parent().vessel_type, "cargo_capacity"))
diff --git a/VesselCargoComponent.gd.uid b/VesselCargoComponent.gd.uid
new file mode 100644
index 0000000..85443bc
--- /dev/null
+++ b/VesselCargoComponent.gd.uid
@@ -0,0 +1 @@
+uid://bo16x4wq6hg5k
diff --git a/VesselCargoComponent.tscn b/VesselCargoComponent.tscn
new file mode 100644
index 0000000..34eafa6
--- /dev/null
+++ b/VesselCargoComponent.tscn
@@ -0,0 +1,4 @@
+[gd_scene load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselCargoComponent.gd" id="1"]
+[node name="CargoComponent" type="Node"]
+script = ExtResource("1")
diff --git a/VesselDefinition.gd b/VesselDefinition.gd
new file mode 100644
index 0000000..0f6637f
--- /dev/null
+++ b/VesselDefinition.gd
@@ -0,0 +1,26 @@
+class_name VesselDefinition
+extends Resource
+
+@export var definition_id: String
+@export var display_name: String
+@export_multiline var description: String
+@export var build_cost: int
+@export var build_time: float = 10.0
+@export var icon: int = 2
+@export var glow_color: Color = Color(0.25, 0.85, 1.0)
+@export var hull_points: PackedVector2Array = PackedVector2Array([
+	Vector2(0, -22), Vector2(-14, 16), Vector2(14, 16),
+])
+@export var capabilities: PackedStringArray = []
+@export var component_scenes: Array[PackedScene] = []
+@export var base_stats: Dictionary = {}
+@export var minimum_stats: Dictionary = {}
+@export var upgrades: Array[Resource] = []
+@export var unlock_id: String
+@export var unlock_name: String
+@export_multiline var unlock_description: String
+@export var unlock_cost: int
+
+
+func has_capability(capability: String) -> bool:
+	return capability in capabilities
diff --git a/VesselDefinition.gd.uid b/VesselDefinition.gd.uid
new file mode 100644
index 0000000..371e084
--- /dev/null
+++ b/VesselDefinition.gd.uid
@@ -0,0 +1 @@
+uid://c6txy3v61blm8
diff --git a/VesselDefinitions.gd b/VesselDefinitions.gd
new file mode 100644
index 0000000..2b33845
--- /dev/null
+++ b/VesselDefinitions.gd
@@ -0,0 +1,24 @@
+class_name VesselDefinitions
+extends RefCounted
+
+const ORDER: PackedStringArray = ["interceptor", "shield", "transporter"]
+const DEFINITIONS: Dictionary = {
+	"interceptor": preload("res://InterceptorVesselDefinition.tres"),
+	"shield": preload("res://ShieldVesselDefinition.tres"),
+	"transporter": preload("res://TransporterVesselDefinition.tres"),
+}
+
+static func get_definition(definition_id: String) -> Resource:
+	return DEFINITIONS.get(definition_id)
+
+static func all() -> Array:
+	var result: Array = []
+	for definition_id in ORDER:
+		result.append(DEFINITIONS[definition_id])
+	return result
+
+static func with_capability(capability: String) -> Resource:
+	for definition in all():
+		if definition.has_capability(capability):
+			return definition
+	return null
diff --git a/VesselDefinitions.gd.uid b/VesselDefinitions.gd.uid
new file mode 100644
index 0000000..d907359
--- /dev/null
+++ b/VesselDefinitions.gd.uid
@@ -0,0 +1 @@
+uid://cgwj1q4nf3ar7
diff --git a/VesselDelivery.gd b/VesselDelivery.gd
index 4c07a6d..6392b62 100644
--- a/VesselDelivery.gd
+++ b/VesselDelivery.gd
@@ -1,8 +1,10 @@
 extends Node2D
 
+const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")
+
 # Visual-only craft-to-mothership flight. GameState owns position/progress;
 # this node just renders a finished hull headed toward the hangar.
-var vessel_type: String = GameState.VESSEL_INTERCEPTOR
+var vessel_type: String = "interceptor"
 
 
 func _ready() -> void:
@@ -11,6 +13,6 @@ func _ready() -> void:
 
 
 func _draw() -> void:
-	var color: Color = Color(0.45, 0.8, 1.0) if vessel_type == GameState.VESSEL_SHIELD else Color(0.95, 0.55, 0.85) if vessel_type == GameState.VESSEL_TRANSPORTER else Color(0.25, 0.85, 1.0)
-	var hull := PackedVector2Array([Vector2(0, -20), Vector2(13, 15), Vector2(0, 9), Vector2(-13, 15)])
-	NeonDraw.draw_glowing_polygon(self, hull, color, 1.0)
+	var definition: Resource = VESSEL_DEFINITIONS.get_definition(vessel_type)
+	if definition != null:
+		NeonDraw.draw_glowing_polygon(self, definition.hull_points, definition.glow_color, 1.0)
diff --git a/VesselDeliveryField.gd b/VesselDeliveryField.gd
index 606b1cf..9b47319 100644
--- a/VesselDeliveryField.gd
+++ b/VesselDeliveryField.gd
@@ -17,9 +17,9 @@ func _process(_delta: float) -> void:
 		var node: Node2D = active.get(i)
 		if node == null or not is_instance_valid(node):
 			node = delivery_script.new()
+			node.vessel_type = String(delivery.type)
 			get_parent().add_child(node)
 			active[i] = node
-		node.vessel_type = String(delivery.type)
 		node.position = pos
 		var direction: Vector2 = (delivery.to as Vector2) - (delivery.from as Vector2)
 		if direction.length() > 0.1:
diff --git a/VesselShieldComponent.gd b/VesselShieldComponent.gd
new file mode 100644
index 0000000..15a8edf
--- /dev/null
+++ b/VesselShieldComponent.gd
@@ -0,0 +1,69 @@
+class_name VesselShieldComponent
+extends Node
+
+const SHIELD_COLOR: Color = Color(0.45, 0.8, 1.0)
+const SHIELD_RADIUS: float = 30.0
+
+var capability_id: String = "shield"
+var charges: int = 0
+var recharge_left: float = 0.0
+var ring: Node2D
+
+
+func setup() -> void:
+	var ship: Node2D = get_parent()
+	var state: Node = ship.get_tree().root.get_node("GameState")
+	ring = NeonPiece.create(ship, Vector2.ZERO, SHIELD_COLOR)
+	var points := PackedVector2Array()
+	for i in range(14):
+		var angle: float = float(i) / 14.0 * TAU
+		points.append(Vector2(cos(angle), sin(angle)) * SHIELD_RADIUS)
+	ring.add_polygon(points, 0.7)
+	ring.queue_redraw()
+	charges = int(state.vessel_stat(ship.vessel_type, "shield_charges"))
+	_update_visual()
+
+
+func apply_stats() -> void:
+	var was_up: bool = charges > 0
+	if was_up:
+		charges = int(_state().vessel_stat(get_parent().vessel_type, "shield_charges"))
+	_update_visual()
+
+
+func tick(delta: float) -> void:
+	var maximum: int = int(_state().vessel_stat(get_parent().vessel_type, "shield_charges"))
+	if charges >= maximum:
+		return
+	recharge_left -= delta
+	if recharge_left <= 0.0:
+		charges += 1
+		recharge_left = _state().vessel_stat(get_parent().vessel_type, "shield_recharge")
+		_update_visual()
+
+
+func is_active() -> bool:
+	return charges > 0
+
+
+func absorb_hit() -> bool:
+	if not is_active():
+		return false
+	charges -= 1
+	recharge_left = _state().vessel_stat(get_parent().vessel_type, "shield_recharge")
+	_update_visual()
+	return true
+
+
+func set_charges(value: int) -> void:
+	charges = value
+	_update_visual()
+
+
+func _state() -> Node:
+	return get_tree().root.get_node("GameState")
+
+
+func _update_visual() -> void:
+	if ring != null:
+		ring.visible = is_active()
diff --git a/VesselShieldComponent.gd.uid b/VesselShieldComponent.gd.uid
new file mode 100644
index 0000000..4ab2382
--- /dev/null
+++ b/VesselShieldComponent.gd.uid
@@ -0,0 +1 @@
+uid://ghacatobxl11
diff --git a/VesselShieldComponent.tscn b/VesselShieldComponent.tscn
new file mode 100644
index 0000000..50ba89e
--- /dev/null
+++ b/VesselShieldComponent.tscn
@@ -0,0 +1,4 @@
+[gd_scene load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselShieldComponent.gd" id="1"]
+[node name="ShieldComponent" type="Node"]
+script = ExtResource("1")
diff --git a/VesselTransportComponent.gd b/VesselTransportComponent.gd
new file mode 100644
index 0000000..7aec619
--- /dev/null
+++ b/VesselTransportComponent.gd
@@ -0,0 +1,9 @@
+class_name VesselTransportComponent
+extends Node
+
+var capability_id: String = "transport"
+var travel_speed: float
+
+func apply_stats() -> void:
+	var state: Node = get_tree().root.get_node("GameState")
+	travel_speed = state.vessel_stat(get_parent().vessel_type, "transport_speed")
diff --git a/VesselTransportComponent.gd.uid b/VesselTransportComponent.gd.uid
new file mode 100644
index 0000000..a2c81fd
--- /dev/null
+++ b/VesselTransportComponent.gd.uid
@@ -0,0 +1 @@
+uid://tsapg8ld1vl8
diff --git a/VesselTransportComponent.tscn b/VesselTransportComponent.tscn
new file mode 100644
index 0000000..a16d4e9
--- /dev/null
+++ b/VesselTransportComponent.tscn
@@ -0,0 +1,4 @@
+[gd_scene load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselTransportComponent.gd" id="1"]
+[node name="TransportComponent" type="Node"]
+script = ExtResource("1")
diff --git a/VesselUpgradeDefinition.gd b/VesselUpgradeDefinition.gd
new file mode 100644
index 0000000..083e092
--- /dev/null
+++ b/VesselUpgradeDefinition.gd
@@ -0,0 +1,11 @@
+class_name VesselUpgradeDefinition
+extends Resource
+
+@export var upgrade_id: String
+@export var display_name: String
+@export_multiline var description: String
+@export var base_cost: int
+@export var max_level: int = 1
+@export var icon: int
+@export var additive_modifiers: Dictionary = {}
+@export var multiplicative_modifiers: Dictionary = {}
diff --git a/VesselUpgradeDefinition.gd.uid b/VesselUpgradeDefinition.gd.uid
new file mode 100644
index 0000000..c615214
--- /dev/null
+++ b/VesselUpgradeDefinition.gd.uid
@@ -0,0 +1 @@
+uid://dw41jux1cn3sw
diff --git a/VesselWeaponComponent.gd b/VesselWeaponComponent.gd
new file mode 100644
index 0000000..1bc6855
--- /dev/null
+++ b/VesselWeaponComponent.gd
@@ -0,0 +1,47 @@
+class_name VesselWeaponComponent
+extends Node
+
+var capability_id: String = "weapon"
+var fire_range: float
+var fire_cooldown: float
+var projectile_damage: int
+var fire_timer: float = 0.0
+var projectile_scene: PackedScene = preload("res://Projectile.tscn")
+
+
+func apply_stats() -> void:
+	var ship: Node = get_parent()
+	var state: Node = ship.get_tree().root.get_node("GameState")
+	fire_range = state.vessel_stat(ship.vessel_type, "fire_range")
+	fire_cooldown = state.vessel_stat(ship.vessel_type, "fire_cooldown")
+	projectile_damage = int(state.vessel_stat(ship.vessel_type, "damage"))
+
+
+func tick(delta: float) -> void:
+	fire_timer -= delta
+	if fire_timer > 0.0:
+		return
+	var ship: Node2D = get_parent()
+	var target: Node2D = _find_nearest_enemy(ship)
+	if target == null:
+		fire_timer = 0.25
+		return
+	var projectile: Node2D = projectile_scene.instantiate()
+	projectile.position = ship.position
+	projectile.damage = projectile_damage
+	ship.get_tree().root.add_child(projectile)
+	projectile.launch(target.position - ship.position)
+	fire_timer = fire_cooldown
+
+
+func _find_nearest_enemy(ship: Node2D) -> Node2D:
+	var nearest: Node2D = null
+	var best_distance: float = fire_range
+	for enemy in ship.get_tree().get_nodes_in_group("enemies"):
+		if not is_instance_valid(enemy):
+			continue
+		var distance: float = ship.position.distance_to(enemy.position)
+		if distance <= best_distance:
+			best_distance = distance
+			nearest = enemy
+	return nearest
diff --git a/VesselWeaponComponent.gd.uid b/VesselWeaponComponent.gd.uid
new file mode 100644
index 0000000..9fd5306
--- /dev/null
+++ b/VesselWeaponComponent.gd.uid
@@ -0,0 +1 @@
+uid://cwo0nkmr4e1sl
diff --git a/VesselWeaponComponent.tscn b/VesselWeaponComponent.tscn
new file mode 100644
index 0000000..b3bd611
--- /dev/null
+++ b/VesselWeaponComponent.tscn
@@ -0,0 +1,4 @@
+[gd_scene load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselWeaponComponent.gd" id="1"]
+[node name="WeaponComponent" type="Node"]
+script = ExtResource("1")
diff --git a/tests/test_building_composition.gd.uid b/tests/test_building_composition.gd.uid
new file mode 100644
index 0000000..f74b39a
--- /dev/null
+++ b/tests/test_building_composition.gd.uid
@@ -0,0 +1 @@
+uid://bljnijxm3n20e
diff --git a/tests/test_hangar_management.gd b/tests/test_hangar_management.gd
index eb6d399..4de3cac 100644
--- a/tests/test_hangar_management.gd
+++ b/tests/test_hangar_management.gd
@@ -68,6 +68,7 @@ func _process(delta: float) -> bool:
 		# own non-overlapping berths to the right only after expansion.
 		var mothership: Node2D = load("res://Building.tscn").instantiate()
 		mothership.set("building_type", GameState.BUILDING_MOTHERSHIP)
+		mothership._ready()
 		controller.current_building = mothership
 		controller.context_actions_expanded = true
 		controller._layout_context_buttons()
diff --git a/tests/test_vessel_composition.gd b/tests/test_vessel_composition.gd
new file mode 100644
index 0000000..f25f447
--- /dev/null
+++ b/tests/test_vessel_composition.gd
@@ -0,0 +1,50 @@
+extends SceneTree
+
+const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")
+
+var ships: Array = []
+var elapsed: float = 0.0
+var game_state: Node
+
+
+func _initialize() -> void:
+	game_state = root.get_node("GameState")
+	var scene: PackedScene = load("res://Ship.tscn")
+	for definition in VESSEL_DEFINITIONS.all():
+		var ship: Area2D = scene.instantiate()
+		ship.vessel_type = definition.definition_id
+		root.add_child(ship)
+		ships.append(ship)
+
+
+func _process(delta: float) -> bool:
+	elapsed += delta
+	if elapsed < 0.1:
+		return false
+	var definitions: Array = VESSEL_DEFINITIONS.all()
+	if ships.size() != definitions.size():
+		return _fail("catalog and composed fleet differ in size")
+	for i in range(definitions.size()):
+		var definition: Resource = definitions[i]
+		var ship: Node = ships[i]
+		if ship.definition == null or ship.definition.definition_id != definition.definition_id:
+			return _fail("%s did not resolve its definition" % definition.definition_id)
+		for capability in definition.capabilities:
+			if not ship.has_capability(capability):
+				return _fail("%s did not compose %s" % [definition.definition_id, capability])
+		if game_state.product_cost(definition.definition_id) != definition.build_cost \
+				or game_state.vessel_name(definition.definition_id) != definition.display_name:
+			return _fail("%s metadata did not come from its definition" % definition.definition_id)
+	if ships[0].has_capability("shield") or not ships[1].has_capability("shield"):
+		return _fail("shield behavior is not controlled by component presence")
+	if ships[2].has_capability("weapon") or not ships[2].has_capability("transport"):
+		return _fail("transporter capabilities were composed incorrectly")
+	print("TEST_VESSEL_COMPOSITION: PASS")
+	quit(0)
+	return true
+
+
+func _fail(message: String) -> bool:
+	print("TEST_VESSEL_COMPOSITION: FAIL (%s)" % message)
+	quit(1)
+	return true
diff --git a/tests/test_vessel_composition.gd.uid b/tests/test_vessel_composition.gd.uid
new file mode 100644
index 0000000..d490e27
--- /dev/null
+++ b/tests/test_vessel_composition.gd.uid
@@ -0,0 +1 @@
+uid://cq73poxld1e35