Repair a broken working tree, and make every crafter press report

The crafter buttons doing nothing was not the crafter: Ship.gd was left
mid-edit and failed to parse (undeclared SHIELD_COLOR/SHIELD_RADIUS, and
a spawn() that only exists on the concrete VFX subclass). A script that
does not compile takes Main.tscn's whole node tree with it, so every
button in the game was dead. The project directory is the one being
played from, so an unfinished edit there is a broken build - finish or
revert before stopping.

With that fixed, the real gap underneath: an order the crafter cannot
pay for is ACCEPTED and queued (#16), which is indistinguishable from a
dead button. Ordering now reports either "building now" or "queued - N
more ore must be delivered here", and the transient message is rendered
LAST so it is the first line read rather than buried under the standing
fleet-capacity note.

test_crafter_feedback covers all three presses and asserts the message
survives the per-frame refresh, which is the specific way this looked
broken before.

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

GameState.gd

@@ -252,6 +252,7 @@ func max_fleet_size() -> int:
 
 func reset_progression() -> void:
 	unlocked.clear()
+	vessel_levels.clear()
 
 
 # --- building stock and production queue (#16) -----------------------------
@@ -294,6 +295,176 @@ func find_building(id: int) -> Dictionary:
 	return {}
 
 
+# --- vessel types and their upgrades (#5) ---------------------------------
+
+# The three things that can be flying around. The first and last double as
+# production order ids, so a vessel type and the order that builds it are the
+# same string rather than two that have to be kept in step.
+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",
+}
+
+const SHIELD_COST: int = 14
+
+# 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.
+const SHIP_BASE_DAMAGE: int = 1
+const SHIP_BASE_COOLDOWN: float = 0.5
+const SHIP_BASE_RANGE: float = 320.0
+const SHIP_BASE_SPEED: float = 460.0
+const SHIP_BASE_ACCEL: float = 450.0
+const SHIELD_BASE_CHARGES: int = 1
+const SHIELD_BASE_RECHARGE: float = 6.0
+const TRANSPORTER_BASE_LOAD: int = 20
+const TRANSPORTER_BASE_SPEED: float = 340.0
+
+var vessel_levels: Dictionary = {}
+
+signal vessel_upgraded(upgrade_id: String)
+
+
+func upgrade_def(id: String) -> Dictionary:
+	for u in VESSEL_UPGRADES:
+		if u.id == id:
+			return u
+	return {}
+
+
+func upgrades_for(vessel: String) -> Array:
+	var out: Array = []
+	for u in VESSEL_UPGRADES:
+		if u.vessel == vessel:
+			out.append(u)
+	return out
+
+
+func upgrade_level(id: String) -> int:
+	return int(vessel_levels.get(id, 0))
+
+
+func upgrade_maxed(id: String) -> bool:
+	var d: Dictionary = upgrade_def(id)
+	return d.is_empty() or upgrade_level(id) >= int(d.max_level)
+
+
+func upgrade_cost(id: String) -> int:
+	var d: Dictionary = upgrade_def(id)
+	if d.is_empty():
+		return 0
+	return int(d.cost) * (upgrade_level(id) + 1)
+
+
+func can_buy_upgrade(id: String) -> bool:
+	return not upgrade_maxed(id) and can_afford(upgrade_cost(id))
+
+
+func buy_upgrade(id: String) -> bool:
+	if not can_buy_upgrade(id):
+		return false
+	if not spend(upgrade_cost(id)):
+		return false
+	vessel_levels[id] = upgrade_level(id) + 1
+	vessel_upgraded.emit(id)
+	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 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 shield_max_charges() -> int:
+	return SHIELD_BASE_CHARGES + upgrade_level("shd_hits")
+
+
+func shield_recharge_time() -> float:
+	return maxf(2.0, SHIELD_BASE_RECHARGE - 1.2 * upgrade_level("shd_recharge"))
+
+
+func transporter_load_limit() -> int:
+	return TRANSPORTER_BASE_LOAD + 8 * upgrade_level("trn_capacity")
+
+
+func transporter_speed() -> float:
+	return TRANSPORTER_BASE_SPEED + 70.0 * upgrade_level("trn_speed")
+
+
 const PRODUCT_SHIP: String = "interceptor"
 const PRODUCT_TRANSPORTER: String = "transporter"
 
@@ -303,6 +474,8 @@ 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
 
 
@@ -704,7 +877,7 @@ func _advance_transporters(delta: float) -> void:
 		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)
+		var leg: float = maxf(distance / transporter_speed(), 0.0001)
 		t.progress += delta / leg
 		if t.progress < 1.0:
 			continue
@@ -719,7 +892,7 @@ func _arrive(t: Dictionary) -> void:
 		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)
+			var take: int = mini(mini(want, rocks), transporter_load_limit())
 			if take <= 0 or target.is_empty():
 				# Nothing to carry, or the building is gone. Go home empty.
 				t.target_id = 0