Created ISaveable interface and made existing saveable classes inherit from it.

scripts/CSharp/Common/CharacterControls/InteractionArea2D.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Linq;
 using Babushka.scripts.CSharp.Common.Services;
 using Godot;

scripts/CSharp/Common/Farming/FieldBehaviour2D.cs

@@ -13,7 +13,7 @@ namespace Babushka.scripts.CSharp.Common.Farming;
 /// Defines the behaviour of the field, i.e. interactions, states and effects.
 /// </summary>
 [GlobalClass]
-public partial class FieldBehaviour2D : Sprite2D
+public partial class FieldBehaviour2D : Sprite2D, ISaveable
 {
     [ExportGroup("Persistence")]
     [Export] public string SaveId = "";

scripts/CSharp/Common/Inventory/InventoryInstance.cs

@@ -7,7 +7,7 @@ using Babushka.scripts.CSharp.Common.Savegame;
 
 namespace Babushka.scripts.CSharp.Common.Inventory;
 
-public partial class InventoryInstance : Node
+public partial class InventoryInstance : Node, ISaveable
 {
     private List<InventorySlot> _slots = new();
     public IReadOnlyList<InventorySlot> Slots => _slots;

scripts/CSharp/Common/Savegame/ISaveable.cs

@@ -0,0 +1,17 @@
+namespace Babushka.scripts.CSharp.Common.Savegame;
+
+/// <summary>
+/// Defines the behaviour of Nodes that have fields that should save / load to disk.
+/// </summary>
+public interface ISaveable 
+{
+    /// <summary>
+    /// Adds or updates the field data that shall be stored to disk.
+    /// </summary>
+    public void UpdateSaveData();
+    
+    /// <summary>
+    /// Loads the field data from disk.
+    /// </summary>
+    public void LoadFromSaveData();
+}