Route trade purchases through checkpoints

Aetheria.State.Verify/Program.cs

@@ -19,6 +19,7 @@ RequireHullConductivityCommitAuthority(root);
 RequireInventoryEntityRenameCommitAuthority(root);
 RequireWeaponGroupCommitAuthority(root);
 RequireInventoryDoubleClickTransferCommitAuthority(root);
+RequireTradePurchaseCommitAuthority(root);
 
 await using var node = await AetheriaStateNode.OpenAsync(statePath, "aetheria-state-verify");
 
@@ -467,6 +468,7 @@ Console.WriteLine("Hull conductivity authority: inventory UI toggles flow throug
 Console.WriteLine("Inventory entity rename authority: UI rename flows through gameplay checkpoint commits");
 Console.WriteLine("Weapon group authority: UI assignment flows through gameplay checkpoint commits");
 Console.WriteLine("Inventory transfer authority: UI transfer and drag/drop requests flow through gameplay checkpoint commits");
+Console.WriteLine("Trade purchase authority: UI buy requests flow through gameplay checkpoint commits");
 
 static void RequireCount(AetheriaMigrationLedger ledger, string documentType, int actual)
 {
@@ -1005,6 +1007,64 @@ static void RequireInventoryDoubleClickTransferCommitAuthority(string root)
     }
 }
 
+static void RequireTradePurchaseCommitAuthority(string root)
+{
+    var actionGameManagerPath = Path.Combine(root, "Assets", "Scripts", "Gameplay", "ActionGameManager.cs");
+    var actionGameManager = File.Exists(actionGameManagerPath)
+        ? File.ReadAllText(actionGameManagerPath)
+        : throw new InvalidOperationException("Cannot verify trade purchase authority; ActionGameManager.cs is missing.");
+
+    var requiredCommits = new[]
+    {
+        "CommitTradePurchase",
+        "QueueRunCheckpoint(\"trade-purchase\")",
+        "Credits -=",
+        "new Ship("
+    };
+
+    var missingCommits = requiredCommits
+        .Where(symbol => !actionGameManager.Contains(symbol, StringComparison.Ordinal))
+        .ToArray();
+
+    if (missingCommits.Length > 0)
+    {
+        throw new InvalidOperationException(
+            "Trade purchase no longer has a gameplay-owned checkpoint commit primitive: " +
+            string.Join(", ", missingCommits));
+    }
+
+    var tradeMenuPath = Path.Combine(root, "Assets", "Scripts", "UI", "Menu", "TradeMenu.cs");
+    var tradeMenu = File.Exists(tradeMenuPath)
+        ? File.ReadAllText(tradeMenuPath)
+        : throw new InvalidOperationException("Cannot verify trade purchase authority; TradeMenu.cs is missing.");
+
+    var forbiddenSymbols = new[]
+    {
+        "GameManager.Credits -=",
+        "Inventory.TryTransferItem(",
+        "new Ship(",
+        ".SetParent(GameManager.DockedEntity)"
+    };
+
+    var hits = File.ReadLines(tradeMenuPath)
+        .Select((line, index) => new { LineNumber = index + 1, Line = line })
+        .Where(line => forbiddenSymbols.Any(symbol => line.Line.Contains(symbol, StringComparison.Ordinal)))
+        .Select(line => $"{Path.GetRelativePath(root, tradeMenuPath)}:{line.LineNumber}: {line.Line.Trim()}")
+        .ToArray();
+
+    if (hits.Length > 0)
+    {
+        throw new InvalidOperationException(
+            "TradeMenu still owns direct purchase mutation: " +
+            string.Join("; ", hits));
+    }
+
+    if (!tradeMenu.Contains("GameManager.CommitTradePurchase", StringComparison.Ordinal))
+    {
+        throw new InvalidOperationException("TradeMenu no longer routes purchases through ActionGameManager.");
+    }
+}
+
 static string ExtractMethodBody(string source, string methodName)
 {
     var signature = "private void " + methodName + "()";

Assets/Scripts/Gameplay/ActionGameManager.cs

@@ -1675,6 +1675,76 @@ public class ActionGameManager : MonoBehaviour
         return true;
     }
 
+    public bool CommitTradePurchase(
+        EquippedCargoBay stationInventory,
+        EquippedCargoBay targetCargo,
+        CraftedItemInstance item,
+        int price,
+        bool createsDockedShip)
+    {
+        if (item == null ||
+            price < 0 ||
+            price > Credits)
+        {
+            return false;
+        }
+
+        if (createsDockedShip)
+        {
+            if (!(item is EquippableItem hull) ||
+                Zone == null ||
+                DockedEntity == null)
+            {
+                return false;
+            }
+
+            var ship = new Ship(ItemManager, Zone, hull, NewEntitySettings) { IsPlayerShip = true };
+            ship.SetParent(DockedEntity);
+            Credits -= price;
+            QueueRunCheckpoint("trade-purchase");
+            return true;
+        }
+
+        if (stationInventory == null ||
+            targetCargo == null ||
+            !stationInventory.TryTransferItem(targetCargo, item))
+        {
+            return false;
+        }
+
+        Credits -= price;
+        QueueRunCheckpoint("trade-purchase");
+        return true;
+    }
+
+    public bool CommitTradePurchase(
+        EquippedCargoBay stationInventory,
+        EquippedCargoBay targetCargo,
+        SimpleCommodity item,
+        int quantity,
+        int unitPrice)
+    {
+        if (stationInventory == null ||
+            targetCargo == null ||
+            item == null ||
+            quantity <= 0 ||
+            unitPrice < 0)
+        {
+            return false;
+        }
+
+        var totalPrice = (long)quantity * unitPrice;
+        if (totalPrice > Credits || totalPrice > int.MaxValue)
+            return false;
+
+        if (!stationInventory.TryTransferItem(targetCargo, item, quantity))
+            return false;
+
+        Credits -= (int)totalPrice;
+        QueueRunCheckpoint("trade-purchase");
+        return true;
+    }
+
     public void CommitEquippedItemOverrideShutdown(EquippedItem item, bool enabled)
     {
         if (item?.EquippableItem == null)

Assets/Scripts/UI/Menu/TradeMenu.cs

@@ -528,41 +528,27 @@ public class TradeMenu : MonoBehaviour
         }
 
         var price = GetTypedTradePrice(item, typedItem);
-        if (price < GameManager.Credits)
+        var isShipHull = !string.IsNullOrWhiteSpace(typedItem?.HullType);
+        if (isShipHull &&
+            !string.Equals(typedItem.HullType, nameof(HullType.Ship), StringComparison.Ordinal))
         {
-            if (!string.IsNullOrWhiteSpace(typedItem?.HullType))
-            {
-                if (!string.Equals(typedItem.HullType, nameof(HullType.Ship), StringComparison.Ordinal))
-                    throw new ArgumentException("Attempted to buy non-ship hull from station, WTF are you doing?!");
-
-                var ship = new Ship(GameManager.ItemManager, GameManager.Zone, item as EquippableItem, GameManager.NewEntitySettings) { IsPlayerShip = true };
-                ship.SetParent(GameManager.DockedEntity);
-
-                GameManager.Credits -= price;
-                UpdateCreditsLabel();
-            }
-            else if (Inventory.TryTransferItem(_targetCargo, item))
-            {
-                GameManager.Credits -= price;
-                UpdateCreditsLabel();
-            }
-            else
-            {
-                Dialog.Clear();
-                Dialog.Title.text = "Unable to buy: Insufficient Cargo Space!";
-                Dialog.Show();
-                Dialog.MoveToCursor();
-                return;
-            }
-        }
-        else
-        {
-            Dialog.Clear();
-            Dialog.Title.text = "Unable to buy: Insufficient Credits!";
-            Dialog.Show();
-            Dialog.MoveToCursor();
+            ShowUnableToBuy("Unsupported hull purchase!");
             return;
         }
+
+        if (price > GameManager.Credits)
+        {
+            ShowUnableToBuy("Insufficient Credits!");
+            return;
+        }
+
+        if (!GameManager.CommitTradePurchase(Inventory, _targetCargo, item, price, isShipHull))
+        {
+            ShowUnableToBuy(isShipHull ? "Unable to create ship!" : "Insufficient Cargo Space!");
+            return;
+        }
+
+        UpdateCreditsLabel();
     }
 
     private void Buy(SimpleCommodity simpleCommodity, int quantity)
@@ -574,40 +560,22 @@ public class TradeMenu : MonoBehaviour
             return;
         }
 
-        var maxStack = typedItem.MaxStack > 0 ? typedItem.MaxStack : 1;
         var price = typedItem.Price;
-        // Up-rounded integer division from https://stackoverflow.com/a/503201
-        int lots = (quantity - 1) / maxStack + 1;
-        int remaining = quantity;
-        for (int i = 0; i < lots; i++)
+        var clampedQuantity = min(quantity, simpleCommodity.Quantity);
+        var totalPrice = (long)clampedQuantity * price;
+        if (totalPrice > GameManager.Credits)
         {
-            int q = min(remaining, maxStack);
-            if (q * price < GameManager.Credits)
-            {
-                if (Inventory.TryTransferItem(_targetCargo, simpleCommodity, quantity))
-                {
-                    GameManager.Credits -= q * price;
-                    UpdateCreditsLabel();
-                    remaining -= q;
-                }
-                else
-                {
-                    Dialog.Clear();
-                    Dialog.Title.text = "Unable to buy: Insufficient Cargo Space!";
-                    Dialog.Show();
-                    Dialog.MoveToCursor();
-                    return;
-                }
-            }
-            else
-            {
-                Dialog.Clear();
-                Dialog.Title.text = "Unable to buy: Insufficient Credits!";
-                Dialog.Show();
-                Dialog.MoveToCursor();
-                return;
-            }
+            ShowUnableToBuy("Insufficient Credits!");
+            return;
         }
+
+        if (!GameManager.CommitTradePurchase(Inventory, _targetCargo, simpleCommodity, clampedQuantity, price))
+        {
+            ShowUnableToBuy("Insufficient Cargo Space!");
+            return;
+        }
+
+        UpdateCreditsLabel();
     }
 
     private int GetTypedTradePrice(CraftedItemInstance item, AetheriaRuntimeCatalogItem typedItem)

docs/aetheria-perfect-machine-map.md

@@ -1004,6 +1004,11 @@ First Aetheria surfaces to publish:
    - Done: move trade menu buy price, ship-hull classification, and simple
      commodity stack-size decisions onto typed catalog rows; inventory transfer
      and ship construction remain the runtime mutation owners.
+   - Done: route trade purchase mutation through gameplay-owned checkpoint
+     commits. `TradeMenu` still presents typed trade rows and calculates display
+     prices, but no longer subtracts credits, transfers purchased cargo, or
+     constructs purchased ships directly. `ActionGameManager.CommitTradePurchase`
+     owns the purchase mutation and queues a typed run checkpoint.
    - Done: move TradeMenu dynamic behavior columns onto typed behavior payload
      fields; the menu no longer hydrates `ItemData` or `BehaviorData` for row
      display, filtering, sorting, or buy decisions.
@@ -1719,7 +1724,9 @@ collects text, gameplay owns the name mutation and checkpoint. Weapon group
 assignment follows the same rule: UI requests membership, gameplay owns the
 group mutation and checkpoint. Inventory double-click transfer follows the same
 rule, and drag/drop placement now shares that commit family: UI requests
-cargo/equipment movement, gameplay owns the move and queues the checkpoint. Any
+cargo/equipment movement, gameplay owns the move and queues the checkpoint.
+Trade purchases follow the same rule: UI requests the purchase, gameplay owns
+credit changes, cargo transfer, ship creation, and checkpoint. Any
 predicate that still needs legacy DTO objects must earn that dependency by
 using behavior objects or simulation-only methods that typed facets do not yet
 expose.