added item probability

actionBlocks_server/src/ActionBlocks.Game/Items/ItemRegistry.cs

@@ -39,16 +39,29 @@ public sealed class ItemRegistry
     }
 }
 
-/// <summary>Decides whether a new piece carries an item and in which of its minos.</summary>
+/// <summary>Decides which minos of a new piece carry an item. Each mino rolls <c>chance</c> (0..1) on its own.</summary>
 public sealed class ItemSpawner(ItemRegistry registry, double chance, Random random)
 {
+    private const int MinosPerPiece = 4;
+
+    private readonly double _chance = double.IsNaN(chance) ? 0 : Math.Clamp(chance, 0, 1);
+
     public Core.PieceSpec Decorate(Core.PieceType type)
     {
-        if (registry.All.Count == 0 || random.NextDouble() >= chance)
+        if (registry.All.Count == 0)
         {
             return new Core.PieceSpec(type);
         }
-        var item = registry.PickRandom(random);
-        return new Core.PieceSpec(type, item.Id, random.Next(4));
+        var items = new string?[MinosPerPiece];
+        var any = false;
+        for (var i = 0; i < MinosPerPiece; i++)
+        {
+            if (random.NextDouble() < _chance)
+            {
+                items[i] = registry.PickRandom(random).Id;
+                any = true;
+            }
+        }
+        return any ? new Core.PieceSpec(type, items) : new Core.PieceSpec(type);
     }
 }