Add project files.

EstadoPersistente.cs

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+using System;
+using System.IO;
+using System.Reflection;
+using System.Windows;
+using Newtonsoft.Json;
+
+namespace libPersistence
+{
+
+    public abstract class EstadoPersistente<T> where T : EstadoPersistente<T>, new()
+    {
+        private static readonly Lazy<T> instance = new Lazy<T>(() => Load());
+
+        static EstadoPersistente()
+        {
+            Application.Current.Exit += OnApplicationExit;
+        }
+
+        public static T Instance => instance.Value;
+
+        private static string GetFileName()
+        {
+            var appName = AppDomain.CurrentDomain.FriendlyName;
+            var className = typeof(T).Name;
+            var folderPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), appName);
+            Directory.CreateDirectory(folderPath);
+            return Path.Combine(folderPath, $"{className}.json");
+        }
+
+        private static T Load()
+        {
+            var fileName = GetFileName();
+            if (File.Exists(fileName))
+            {
+                var settings = new JsonSerializerSettings
+                {
+                    TypeNameHandling = TypeNameHandling.Auto,
+                    ObjectCreationHandling = ObjectCreationHandling.Replace,
+                    // PreserveReferencesHandling = PreserveReferencesHandling.Objects,
+                    ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor
+                };
+                var jsonString = File.ReadAllText(fileName);
+                return JsonConvert.DeserializeObject<T>(jsonString) ?? new T();
+            }
+            return new T();
+        }
+
+        private static void OnApplicationExit(object sender, ExitEventArgs e)
+        {
+            Instance.Save();
+        }
+
+        public void Save()
+        {
+            var fileName = GetFileName();
+            var settings = new JsonSerializerSettings
+            {
+                Formatting = Formatting.Indented,
+                // PreserveReferencesHandling = PreserveReferencesHandling.Objects,
+                NullValueHandling = NullValueHandling.Ignore,
+                TypeNameHandling = TypeNameHandling.Auto
+            };
+            // Serializar
+            var serializedData = JsonConvert.SerializeObject(this, settings);
+            File.WriteAllText(fileName, serializedData);
+        }
+    }
+
+
+}

libPersistence.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0-windows</TargetFramework>
+    <Nullable>enable</Nullable>
+    <UseWPF>true</UseWPF>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+  </ItemGroup>
+
+</Project>

libPersistence.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.10.34928.147
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "libPersistence", "libPersistence.csproj", "{DF086CA8-DF0E-4A37-9527-3823EB617A35}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{DF086CA8-DF0E-4A37-9527-3823EB617A35}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DF086CA8-DF0E-4A37-9527-3823EB617A35}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{DF086CA8-DF0E-4A37-9527-3823EB617A35}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{DF086CA8-DF0E-4A37-9527-3823EB617A35}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {848C4205-DE9A-4A71-9A42-23D49A1CBA36}
+	EndGlobalSection
+EndGlobal