Fix drag race condition and stale pointer events

Mark items as dragging before updating inventory state to prevent
the spawner from destroying containers mid-drag. Move inventory
removal to drop time for lost items, and add guards to ignore
stale pointer events on inactive containers.

packages/sts-like-viewer/src/widgets/InventoryItemSpawner.ts

@@ -37,9 +37,10 @@ export interface InventoryItemSpawnerOptions {
  * Items currently being dragged are excluded from getData() to prevent
  * the spawner from respawning them while they're in flight.
  */
-export class InventoryItemSpawner
-  implements Spawner<InventoryItem<GameItemMeta>, Phaser.GameObjects.Container>
-{
+export class InventoryItemSpawner implements Spawner<
+  InventoryItem<GameItemMeta>,
+  Phaser.GameObjects.Container
+> {
   private scene: Phaser.Scene;
   private gameState: MutableSignal<RunState>;
   private parentContainer: Phaser.GameObjects.Container;
@@ -102,6 +103,7 @@ export class InventoryItemSpawner
     obj: Phaser.GameObjects.Container,
     _item: InventoryItem<GameItemMeta>,
   ): void {
+    obj.removeAllListeners();
     obj.destroy();
   }
 
@@ -248,6 +250,8 @@ export class InventoryItemSpawner
     container: Phaser.GameObjects.Container,
   ): void {
     container.on("pointerdown", (pointer: Phaser.Input.Pointer) => {
+      // Guard against stale events firing on destroyed containers
+      if (!container.scene || !container.active) return;
       if (this.isLocked()) return;
       if (this.isDragging()) return;
       if (pointer.button === 0) {

packages/sts-like-viewer/src/widgets/InventoryWidget.ts

@@ -140,12 +140,9 @@ export class InventoryWidget {
     item: InventoryItem<GameItemMeta>,
     itemContainer: Phaser.GameObjects.Container,
   ): void {
-    // Remove from inventory state
-    this.gameState.produce((state) => {
-      removeItemFromGrid(state.inventory, itemId);
-    });
-
-    // Mark as dragging so spawner excludes it from getData()
+    // Mark as dragging FIRST so spawner excludes it from getData().
+    // This prevents the spawner effect from destroying the container
+    // when we later update the inventory state.
     this.itemSpawner.markDragging(itemId);
 
     // Start drag session
@@ -169,9 +166,14 @@ export class InventoryWidget {
     x: number,
     y: number,
   ): void {
+    // Remove from inventory since it's dropped outside valid placement
+    this.gameState.produce((state) => {
+      removeItemFromGrid(state.inventory, itemId);
+    });
+
     this.lostItemManager.createLostItem(itemId, shape, transform, meta, x, y);
 
-    // Unmark dragging — item is now "lost" and no longer in inventory
+    // Unmark dragging — item is now "lost" and managed by LostItemManager
     this.itemSpawner.unmarkDragging(itemId);
   }
 

packages/sts-like-viewer/src/widgets/LostItemManager.ts

@@ -107,6 +107,8 @@ export class LostItemManager {
     container.setInteractive(hitRect, Phaser.Geom.Rectangle.Contains);
 
     container.on("pointerdown", (pointer: Phaser.Input.Pointer) => {
+      // Guard against stale events firing on destroyed containers
+      if (!container.scene || !container.active) return;
       if (this.isDragging()) return;
       if (pointer.button === 0) {
         this.onLostItemDragStart(itemId, container);