Merge pull request #344 from philippjbauer/master

Rebuilt ChatSession class

LLama.Examples/Assets/chat-with-bob.json

@@ -0,0 +1,24 @@
+{
+    "messages": [
+        {
+            "author_role": "System",
+            "content": "Transcript of a dialog, where the User interacts with an Assistant named Bob. Bob is helpful, kind, honest, good at writing, and never fails to answer the User's requests immediately and with precision."
+        },
+        {
+            "author_role": "User",
+            "content": "Hello, Bob."
+        },
+        {
+            "author_role": "Assistant",
+            "content": "Hello. How may I help you today?"
+        },
+        {
+            "author_role": "User",
+            "content": "Please tell me the largest city in Europe."
+        },
+        {
+            "author_role": "Assistant",
+            "content": "Sure. The largest city in Europe is Istanbul, Turkey."
+        }
+    ]
+}

LLama.Examples/Assets/chat-with-kunkun-chinese.json

@@ -0,0 +1,24 @@
+{
+    "messages": [
+        {
+            "author_role": "System",
+            "content": "下面是一段你和用户的对话，你叫坤坤，是一个在各方面都拥有丰富经验的助理，你非常乐于回答用户的问题和帮助用户。"
+        },
+        {
+            "author_role": "User",
+            "content": "你好，坤坤。"
+        },
+        {
+            "author_role": "Assistant",
+            "content": "你好，有什么我能帮助你的吗？"
+        },
+        {
+            "author_role": "User",
+            "content": "中国的首都是哪座城市？"
+        },
+        {
+            "author_role": "Assistant",
+            "content": "中国的首都是北京市。"
+        }
+    ]
+}

LLama.Examples/Examples/ChatChineseGB2312.cs

@@ -1,69 +1,122 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using System.Text;
 using LLama.Common;
 
-namespace LLama.Examples.Examples
+namespace LLama.Examples.Examples;
+
+public class ChatChineseGB2312
 {
-    public class ChatChineseGB2312
+    private static string ConvertEncoding(string input, Encoding original, Encoding target)
+    {
+        byte[] bytes = original.GetBytes(input);
+        var convertedBytes = Encoding.Convert(original, target, bytes);
+        return target.GetString(convertedBytes);
+    }
+
+    public static async Task Run()
     {
-        private static string ConvertFromEncodingToAnother(string input, Encoding original, Encoding target)
+        // Register provider for GB2312 encoding
+        Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
+
+        Console.ForegroundColor = ConsoleColor.Yellow;
+        Console.WriteLine("This example shows how to use Chinese with gb2312 encoding, which is common in windows. It's recommended" +
+            " to use https://huggingface.co/hfl/chinese-alpaca-2-7b-gguf/blob/main/ggml-model-q5_0.gguf, which has been verified by LLamaSharp developers.");
+        Console.ForegroundColor = ConsoleColor.White;
+
+        Console.Write("Please input your model path: ");
+        var modelPath = Console.ReadLine();
+
+        var parameters = new ModelParams(modelPath)
+        {
+            ContextSize = 1024,
+            Seed = 1337,
+            GpuLayerCount = 5,
+            Encoding = Encoding.UTF8
+        };
+        using var model = LLamaWeights.LoadFromFile(parameters);
+        using var context = model.CreateContext(parameters);
+        var executor = new InteractiveExecutor(context);
+
+        ChatSession session;
+        if (Directory.Exists("Assets/chat-with-kunkun-chinese"))
+        {
+            Console.ForegroundColor = ConsoleColor.Yellow;
+            Console.WriteLine("Loading session from disk.");
+            Console.ForegroundColor = ConsoleColor.White;
+
+            session = new ChatSession(executor);
+            session.LoadSession("Assets/chat-with-kunkun-chinese");
+        }
+        else
         {
-            byte[] bytes = original.GetBytes(input);
-            var convertedBytes = Encoding.Convert(original, target, bytes);
-            return target.GetString(convertedBytes);
+            var chatHistoryJson = File.ReadAllText("Assets/chat-with-kunkun-chinese.json");
+            ChatHistory chatHistory = ChatHistory.FromJson(chatHistoryJson) ?? new ChatHistory();
+
+            session = new ChatSession(executor, chatHistory);
         }
 
-        public static async Task Run()
+        session
+            .WithHistoryTransform(new LLamaTransforms.DefaultHistoryTransform("用户", "坤坤"));
+
+        InferenceParams inferenceParams = new InferenceParams()
         {
-            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance); // Register gb2312 encoding
-            Console.Write("Please input your model path: ");
-            var modelPath = Console.ReadLine();
-            var prompt = File.ReadAllText("Assets/chat-with-kunkun-chinese.txt", encoding: Encoding.GetEncoding("gb2312")).Trim();
-            prompt = ConvertFromEncodingToAnother(prompt, Encoding.GetEncoding("gb2312"), Encoding.UTF8);
+            Temperature = 0.9f,
+            AntiPrompts = new List<string> { "用户：" }
+        };
 
-            var parameters = new ModelParams(modelPath)
-            {
-                ContextSize = 1024,
-                Seed = 1337,
-                GpuLayerCount = 20,
-                Encoding = Encoding.UTF8
-            };
-            using var model = LLamaWeights.LoadFromFile(parameters);
-            using var context = model.CreateContext(parameters);
-            var executor = new InteractiveExecutor(context);
+        Console.ForegroundColor = ConsoleColor.Yellow;
+        Console.WriteLine("The chat session has started.");
 
-            var session = new ChatSession(executor).WithHistoryTransform(new LLamaTransforms.DefaultHistoryTransform("用户"));
+        // show the prompt
+        Console.ForegroundColor = ConsoleColor.White;
+        Console.Write("用户：");
+        Console.ForegroundColor = ConsoleColor.Green;
+        string userInput = Console.ReadLine() ?? "";
 
-            Console.ForegroundColor = ConsoleColor.Yellow;
-            Console.WriteLine("This example shows how to use Chinese with gb2312 encoding, which is common in windows. It's recommended" +
-                " to use https://huggingface.co/hfl/chinese-alpaca-2-7b-gguf/blob/main/ggml-model-q5_0.gguf, which has been verified by LLamaSharp developers.");
-            Console.ForegroundColor = ConsoleColor.White;
+        while (userInput != "exit")
+        {
+            // Convert the encoding from gb2312 to utf8 for the language model
+            // and later saving to the history json file.
+            userInput = ConvertEncoding(userInput, Encoding.GetEncoding("gb2312"), Encoding.UTF8);
 
-            // show the prompt
-            Console.Write(prompt);
-            while (true)
+            if (userInput == "save")
             {
-                await foreach (var text in session.ChatAsync(prompt, new InferenceParams()
+                session.SaveSession("Assets/chat-with-kunkun-chinese");
+                Console.ForegroundColor = ConsoleColor.Yellow;
+                Console.WriteLine("Session saved.");
+            }
+            else if (userInput == "regenerate")
+            {
+                Console.ForegroundColor = ConsoleColor.Yellow;
+                Console.WriteLine("Regenerating last response ...");
+
+                await foreach (
+                    var text
+                    in session.RegenerateAssistantMessageAsync(
+                        inferenceParams))
                 {
-                    Temperature = 0.3f,
-                    TopK = 5,
-                    TopP = 0.85f,
-                    AntiPrompts = new List<string> { "用户：" },
-                    MaxTokens = 2048,
-                    RepeatPenalty = 1.05f
-                }))
+                    Console.ForegroundColor = ConsoleColor.White;
+
+                    // Convert the encoding from utf8 to gb2312 for the console output.
+                    Console.Write(ConvertEncoding(text, Encoding.UTF8, Encoding.GetEncoding("gb2312")));
+                }
+            }
+            else
+            {
+                await foreach (
+                    var text
+                    in session.ChatAsync(
+                        new ChatHistory.Message(AuthorRole.User, userInput),
+                        inferenceParams))
                 {
-                    //Console.Write(text);
-                    Console.Write(ConvertFromEncodingToAnother(text, Encoding.UTF8, Encoding.GetEncoding("gb2312")));
+                    Console.ForegroundColor = ConsoleColor.White;
+                    Console.Write(text);
                 }
-
-                Console.ForegroundColor = ConsoleColor.Green;
-                prompt = Console.ReadLine();
-                Console.ForegroundColor = ConsoleColor.White;
             }
+
+            Console.ForegroundColor = ConsoleColor.Green;
+            userInput = Console.ReadLine() ?? "";
+
+            Console.ForegroundColor = ConsoleColor.White;
         }
     }
 }

LLama.Examples/Examples/ChatSessionStripRoleName.cs

@@ -1,44 +1,61 @@
 using LLama.Common;
 
-namespace LLama.Examples.Examples
+namespace LLama.Examples.Examples;
+
+public class ChatSessionStripRoleName
 {
-    public class ChatSessionStripRoleName
+    public static async Task Run()
     {
-        public static async Task Run()
+        Console.Write("Please input your model path: ");
+        var modelPath = Console.ReadLine();
+
+        var parameters = new ModelParams(modelPath)
         {
-            Console.Write("Please input your model path: ");
-            var modelPath = Console.ReadLine();
-            var prompt = File.ReadAllText("Assets/chat-with-bob.txt").Trim();
+            ContextSize = 1024,
+            Seed = 1337,
+            GpuLayerCount = 5
+        };
+        using var model = LLamaWeights.LoadFromFile(parameters);
+        using var context = model.CreateContext(parameters);
+        var executor = new InteractiveExecutor(context);
 
-            var parameters = new ModelParams(modelPath)
-            {
-                ContextSize = 1024,
-                Seed = 1337,
-                GpuLayerCount = 5
-            };
-            using var model = LLamaWeights.LoadFromFile(parameters);
-            using var context = model.CreateContext(parameters);
-            var executor = new InteractiveExecutor(context);
-
-            var session = new ChatSession(executor).WithOutputTransform(new LLamaTransforms.KeywordTextOutputStreamTransform(new string[] { "User:", "Bob:" }, redundancyLength: 8));
-
-            Console.ForegroundColor = ConsoleColor.Yellow;
-            Console.WriteLine("The chat session has started. The role names won't be printed.");
-            Console.ForegroundColor = ConsoleColor.White;
+        var chatHistoryJson = File.ReadAllText("Assets/chat-with-bob.json");
+        ChatHistory chatHistory = ChatHistory.FromJson(chatHistoryJson) ?? new ChatHistory();
 
-            // show the prompt
-            Console.Write(prompt);
-            while (true)
-            {
-                await foreach (var text in session.ChatAsync(prompt, new InferenceParams() { Temperature = 0.6f, AntiPrompts = new List<string> { "User:" } }))
-                {
-                    Console.Write(text);
-                }
+        ChatSession session = new(executor, chatHistory);
+        session.WithOutputTransform(new LLamaTransforms.KeywordTextOutputStreamTransform(
+            new string[] { "User:", "Assistant:" },
+            redundancyLength: 8));
+
+        InferenceParams inferenceParams = new InferenceParams()
+        {
+            Temperature = 0.9f,
+            AntiPrompts = new List<string> { "User:" }
+        };
 
-                Console.ForegroundColor = ConsoleColor.Green;
-                prompt = Console.ReadLine();
+        Console.ForegroundColor = ConsoleColor.Yellow;
+        Console.WriteLine("The chat session has started.");
+
+        // show the prompt
+        Console.ForegroundColor = ConsoleColor.Green;
+        string userInput = Console.ReadLine() ?? "";
+
+        while (userInput != "exit")
+        {
+            await foreach (
+                var text
+                in session.ChatAsync(
+                    new ChatHistory.Message(AuthorRole.User, userInput),
+                    inferenceParams))
+            {
                 Console.ForegroundColor = ConsoleColor.White;
+                Console.Write(text);
             }
+
+            Console.ForegroundColor = ConsoleColor.Green;
+            userInput = Console.ReadLine() ?? "";
+
+            Console.ForegroundColor = ConsoleColor.White;
         }
     }
 }

LLama.Examples/Examples/ChatSessionWithHistory.cs

@@ -0,0 +1,98 @@
+using LLama.Common;
+
+namespace LLama.Examples.Examples;
+
+public class ChatSessionWithHistory
+{
+    public static async Task Run()
+    {
+        Console.Write("Please input your model path: ");
+        var modelPath = Console.ReadLine();
+
+        var parameters = new ModelParams(modelPath)
+        {
+            ContextSize = 1024,
+            Seed = 1337,
+            GpuLayerCount = 5
+        };
+        using var model = LLamaWeights.LoadFromFile(parameters);
+        using var context = model.CreateContext(parameters);
+        var executor = new InteractiveExecutor(context);
+
+        ChatSession session;
+        if (Directory.Exists("Assets/chat-with-bob"))
+        {
+            Console.ForegroundColor = ConsoleColor.Yellow;
+            Console.WriteLine("Loading session from disk.");
+            Console.ForegroundColor = ConsoleColor.White;
+
+            session = new ChatSession(executor);
+            session.LoadSession("Assets/chat-with-bob");
+        }
+        else
+        {
+            var chatHistoryJson = File.ReadAllText("Assets/chat-with-bob.json");
+            ChatHistory chatHistory = ChatHistory.FromJson(chatHistoryJson) ?? new ChatHistory();
+
+            session = new ChatSession(executor, chatHistory);
+        }
+
+        session.WithOutputTransform(new LLamaTransforms.KeywordTextOutputStreamTransform(
+            new string[] { "User:", "Assistant:" },
+            redundancyLength: 8));
+
+        InferenceParams inferenceParams = new InferenceParams()
+        {
+            Temperature = 0.9f,
+            AntiPrompts = new List<string> { "User:" }
+        };
+
+        Console.ForegroundColor = ConsoleColor.Yellow;
+        Console.WriteLine("The chat session has started.");
+
+        // show the prompt
+        Console.ForegroundColor = ConsoleColor.Green;
+        string userInput = Console.ReadLine() ?? "";
+
+        while (userInput != "exit")
+        {
+            if (userInput == "save")
+            {
+                session.SaveSession("Assets/chat-with-bob");
+                Console.ForegroundColor = ConsoleColor.Yellow;
+                Console.WriteLine("Session saved.");
+            }
+            else if (userInput == "regenerate")
+            {
+                Console.ForegroundColor = ConsoleColor.Yellow;
+                Console.WriteLine("Regenerating last response ...");
+
+                await foreach (
+                    var text
+                    in session.RegenerateAssistantMessageAsync(
+                        inferenceParams))
+                {
+                    Console.ForegroundColor = ConsoleColor.White;
+                    Console.Write(text);
+                }
+            }
+            else
+            {
+                await foreach (
+                    var text
+                    in session.ChatAsync(
+                        new ChatHistory.Message(AuthorRole.User, userInput),
+                        inferenceParams))
+                {
+                    Console.ForegroundColor = ConsoleColor.White;
+                    Console.Write(text);
+                }
+            }
+
+            Console.ForegroundColor = ConsoleColor.Green;
+            userInput = Console.ReadLine() ?? "";
+
+            Console.ForegroundColor = ConsoleColor.White;
+        }
+    }
+}

LLama.Examples/Examples/ChatSessionWithRoleName.cs

@@ -1,44 +1,58 @@
 using LLama.Common;
 
-namespace LLama.Examples.Examples
+namespace LLama.Examples.Examples;
+
+public class ChatSessionWithRoleName
 {
-    public class ChatSessionWithRoleName
+    public static async Task Run()
     {
-        public static async Task Run()
+        Console.Write("Please input your model path: ");
+        var modelPath = Console.ReadLine();
+
+        var parameters = new ModelParams(modelPath)
         {
-            Console.Write("Please input your model path: ");
-            var modelPath = Console.ReadLine();
-            var prompt = File.ReadAllText("Assets/chat-with-bob.txt").Trim();
+            ContextSize = 1024,
+            Seed = 1337,
+            GpuLayerCount = 5
+        };
+        using var model = LLamaWeights.LoadFromFile(parameters);
+        using var context = model.CreateContext(parameters);
+        var executor = new InteractiveExecutor(context);
 
-            var parameters = new ModelParams(modelPath)
-            {
-                ContextSize = 1024,
-                Seed = 1337,
-                GpuLayerCount = 5
-            };
-            using var model = LLamaWeights.LoadFromFile(parameters);
-            using var context = model.CreateContext(parameters);
-            var executor = new InteractiveExecutor(context);
-
-            var session = new ChatSession(executor);
-
-            Console.ForegroundColor = ConsoleColor.Yellow;
-            Console.WriteLine("The chat session has started. In this example, the prompt is printed for better visual result.");
-            Console.ForegroundColor = ConsoleColor.White;
+        var chatHistoryJson = File.ReadAllText("Assets/chat-with-bob.json");
+        ChatHistory chatHistory = ChatHistory.FromJson(chatHistoryJson) ?? new ChatHistory();
 
-            // show the prompt
-            Console.Write(prompt);
-            while (true)
-            {
-                await foreach (var text in session.ChatAsync(prompt, new InferenceParams() { Temperature = 0.6f, AntiPrompts = new List<string> { "User:" } }))
-                {
-                    Console.Write(text);
-                }
+        ChatSession session = new(executor, chatHistory);
+
+        InferenceParams inferenceParams = new InferenceParams()
+        {
+            Temperature = 0.9f,
+            AntiPrompts = new List<string> { "User:" }
+        };
 
-                Console.ForegroundColor = ConsoleColor.Green;
-                prompt = Console.ReadLine();
+        Console.ForegroundColor = ConsoleColor.Yellow;
+        Console.WriteLine("The chat session has started.");
+
+        // show the prompt
+        Console.ForegroundColor = ConsoleColor.Green;
+        string userInput = Console.ReadLine() ?? "";
+
+        while (userInput != "exit")
+        {
+            await foreach (
+                var text
+                in session.ChatAsync(
+                    new ChatHistory.Message(AuthorRole.User, userInput),
+                    inferenceParams))
+            {
                 Console.ForegroundColor = ConsoleColor.White;
+                Console.Write(text);
             }
+
+            Console.ForegroundColor = ConsoleColor.Green;
+            userInput = Console.ReadLine() ?? "";
+
+            Console.ForegroundColor = ConsoleColor.White;
         }
     }
 }

LLama.Examples/Examples/LoadAndSaveSession.cs

@@ -1,4 +1,5 @@
-using LLama.Common;
+using DocumentFormat.OpenXml.Bibliography;
+using LLama.Common;
 
 namespace LLama.Examples.Examples
 {
@@ -30,7 +31,15 @@ namespace LLama.Examples.Examples
             Console.Write(prompt);
             while (true)
             {
-                await foreach (var text in session.ChatAsync(prompt, new InferenceParams() { Temperature = 0.6f, AntiPrompts = new List<string> { "User:" } }))
+                await foreach (
+                    var text
+                    in session.ChatAsync(
+                        new ChatHistory.Message(AuthorRole.User, prompt),
+                        new InferenceParams()
+                        {
+                            Temperature = 0.6f,
+                            AntiPrompts = new List<string> { "User:" }
+                        }))
                 {
                     Console.Write(text);
                 }

LLama.Examples/Examples/Runner.cs

@@ -6,8 +6,10 @@ public class Runner
 {
     private static readonly Dictionary<string, Func<Task>> Examples = new()
     {
+        { "Run a chat session with history.", ChatSessionWithHistory.Run },
         { "Run a chat session without stripping the role names.", ChatSessionWithRoleName.Run },
         { "Run a chat session with the role names stripped.", ChatSessionStripRoleName.Run },
+        { "Run a chat session in Chinese GB2312 encoding", ChatChineseGB2312.Run },
         { "Interactive mode chat by using executor.", InteractiveModeExecute.Run },
         { "Instruct mode chat by using executor.", InstructModeExecute.Run },
         { "Stateless mode chat by using executor.", StatelessModeExecute.Run },
@@ -23,7 +25,6 @@ public class Runner
         { "Coding Assistant.", CodingAssistant.Run },
         { "Batch Decoding.", BatchedDecoding.Run },
         { "SK Kernel Memory.", KernelMemory.Run },
-        { "Chinese gb2312 chat", ChatChineseGB2312.Run }, 
         { "Exit", async () => Environment.Exit(0) }
     };
 

LLama.Examples/LLama.Examples.csproj

@@ -2,7 +2,7 @@
   <Import Project="..\LLama\LLamaSharp.Runtime.targets" />
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <Platforms>AnyCPU;x64</Platforms>
@@ -41,6 +41,12 @@
   </ItemGroup>
 
   <ItemGroup>
+    <None Update="Assets\chat-with-bob.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+    <None Update="Assets\chat-with-kunkun-chinese.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
     <None Update="Assets\chat-with-bob.txt">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>

LLama.KernelMemory/LLamaSharp.KernelMemory.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 

LLama.WebAPI/Services/StatefulChatService.cs

@@ -11,8 +11,7 @@ public class StatefulChatService : IDisposable
     private readonly LLamaContext _context;
     private bool _continue = false;
 
-    private const string SystemPrompt = "Transcript of a dialog, where the User interacts with an Assistant. Assistant is helpful, kind, honest, good at writing, and never fails to answer the User's requests immediately and with precision.\n\n"
-                                       + "User: ";
+    private const string SystemPrompt = "Transcript of a dialog, where the User interacts with an Assistant. Assistant is helpful, kind, honest, good at writing, and never fails to answer the User's requests immediately and with precision.";
 
     public StatefulChatService(IConfiguration configuration)
     {
@@ -25,7 +24,9 @@ public class StatefulChatService : IDisposable
         using var weights = LLamaWeights.LoadFromFile(@params);
 
         _context = new LLamaContext(weights, @params);
+
         _session = new ChatSession(new InteractiveExecutor(_context));
+        _session.History.AddMessage(Common.AuthorRole.System, SystemPrompt);
     }
 
     public void Dispose()
@@ -35,10 +36,8 @@ public class StatefulChatService : IDisposable
 
     public async Task<string> Send(SendMessageInput input)
     {
-        var userInput = input.Text;
         if (!_continue)
         {
-            userInput = SystemPrompt + userInput;
             Console.Write(SystemPrompt);
             _continue = true;
         }
@@ -47,11 +46,14 @@ public class StatefulChatService : IDisposable
         Console.Write(input.Text);
 
         Console.ForegroundColor = ConsoleColor.White;
-        var outputs = _session.ChatAsync(userInput, new Common.InferenceParams()
-        {
-            RepeatPenalty = 1.0f,
-            AntiPrompts = new string[] { "User:" },
-        });
+        var outputs = _session.ChatAsync(
+            new Common.ChatHistory.Message(Common.AuthorRole.User, input.Text),
+            new Common.InferenceParams()
+            {
+                RepeatPenalty = 1.0f,
+                AntiPrompts = new string[] { "User:" },
+            });
+
         var result = "";
         await foreach (var output in outputs)
         {
@@ -64,10 +66,8 @@ public class StatefulChatService : IDisposable
 
     public async IAsyncEnumerable<string> SendStream(SendMessageInput input)
     {
-        var userInput = input.Text;
         if (!_continue)
         {
-            userInput = SystemPrompt + userInput;
             Console.Write(SystemPrompt);
             _continue = true;
         }
@@ -76,11 +76,14 @@ public class StatefulChatService : IDisposable
         Console.Write(input.Text);
 
         Console.ForegroundColor = ConsoleColor.White;
-        var outputs = _session.ChatAsync(userInput, new Common.InferenceParams()
-        {
-            RepeatPenalty = 1.0f,
-            AntiPrompts = new string[] { "User:" },
-        });
+        var outputs = _session.ChatAsync(
+            new Common.ChatHistory.Message(Common.AuthorRole.User, input.Text)
+            , new Common.InferenceParams()
+            {
+                RepeatPenalty = 1.0f,
+                AntiPrompts = new string[] { "User:" },
+            });
+
         await foreach (var output in outputs)
         {
             Console.Write(output);

LLama/ChatSession.cs

@@ -1,246 +1,496 @@
-using LLama.Abstractions;
-using LLama.Common;
 using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Runtime.CompilerServices;
-using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+using LLama.Abstractions;
+using LLama.Common;
 using static LLama.InteractiveExecutor;
 
-namespace LLama
+namespace LLama;
+
+/// <summary>
+/// The main chat session class.
+/// </summary>
+public class ChatSession
 {
+    private const string _modelStateFilename = "ModelState.st";
+    private const string _executorStateFilename = "ExecutorState.json";
+    private const string _hsitoryFilename = "ChatHistory.json";
+
     /// <summary>
-    /// The main chat session class.
-    /// </summary>
-    public class ChatSession
-    {
-        private readonly ILLamaExecutor _executor;
-        private readonly ChatHistory _history;
-
-        private const string _executorStateFilename = "ExecutorState.json";
-        private const string _modelStateFilename = "ModelState.st";
-
-        /// <summary>
-        /// The executor for this session.
-        /// </summary>
-        public ILLamaExecutor Executor => _executor;
-        /// <summary>
-        /// The chat history for this session.
-        /// </summary>
-        public ChatHistory History => _history;
-        /// <summary>
-        /// The history transform used in this session.
-        /// </summary>
-        public IHistoryTransform HistoryTransform { get; set; } = new LLamaTransforms.DefaultHistoryTransform();
-        /// <summary>
-        /// The input transform pipeline used in this session.
-        /// </summary>
-        public List<ITextTransform> InputTransformPipeline { get; set; } = new();
-        /// <summary>
-        /// The output transform used in this session.
-        /// </summary>
-        public ITextStreamTransform OutputTransform = new LLamaTransforms.EmptyTextOutputStreamTransform();
-
-        /// <summary>
-        /// 
-        /// </summary>
-        /// <param name="executor">The executor for this session</param>
-        public ChatSession(ILLamaExecutor executor)
-        {
-            _executor = executor;
-            _history = new ChatHistory();
-        }
-
-        /// <summary>
-        /// Use a custom history transform.
-        /// </summary>
-        /// <param name="transform"></param>
-        /// <returns></returns>
-        public ChatSession WithHistoryTransform(IHistoryTransform transform)
-        {
-            HistoryTransform = transform;
-            return this;
-        }
-
-        /// <summary>
-        /// Add a text transform to the input transform pipeline.
-        /// </summary>
-        /// <param name="transform"></param>
-        /// <returns></returns>
-        public ChatSession AddInputTransform(ITextTransform transform)
-        {
-            InputTransformPipeline.Add(transform);
-            return this;
-        }
-
-        /// <summary>
-        /// Use a custom output transform.
-        /// </summary>
-        /// <param name="transform"></param>
-        /// <returns></returns>
-        public ChatSession WithOutputTransform(ITextStreamTransform transform)
-        {
-            OutputTransform = transform;
-            return this;
-        }
-
-        /// <summary>
-        /// 
-        /// </summary>
-        /// <param name="path">The directory name to save the session. If the directory does not exist, a new directory will be created.</param>
-        public virtual void SaveSession(string path)
-        {
-            if (!Directory.Exists(path))
-            {
-                Directory.CreateDirectory(path);
-            }
-            _executor.Context.SaveState(Path.Combine(path, _modelStateFilename));
-            if (Executor is StatelessExecutor)
-            {
+    /// The executor for this session.
+    /// </summary>
+    public ILLamaExecutor Executor { get; private set; }
 
-            }
-            else if (Executor is StatefulExecutorBase statefulExecutor)
-            {
-                statefulExecutor.SaveState(Path.Combine(path, _executorStateFilename));
-            }
-            else
-            {
-                throw new System.NotImplementedException("You're using a customized executor. Please inherit ChatSession and rewrite the method.");
-            }
+    /// <summary>
+    /// The chat history for this session.
+    /// </summary>
+    public ChatHistory History { get; private set; } = new();
+
+    /// <summary>
+    /// The history transform used in this session.
+    /// </summary>
+    public IHistoryTransform HistoryTransform { get; set; } = new LLamaTransforms.DefaultHistoryTransform();
+
+    /// <summary>
+    /// The input transform pipeline used in this session.
+    /// </summary>
+    public List<ITextTransform> InputTransformPipeline { get; set; } = new();
+
+    /// <summary>
+    /// The output transform used in this session.
+    /// </summary>
+    public ITextStreamTransform OutputTransform = new LLamaTransforms.EmptyTextOutputStreamTransform();
+
+    /// <summary>
+    /// Create a new chat session.
+    /// </summary>
+    /// <param name="executor">The executor for this session</param>
+    public ChatSession(ILLamaExecutor executor)
+    {
+        // Check if executor has StatefulExecutorBase as base class
+        if (executor is not StatefulExecutorBase)
+        {
+            throw new ArgumentException("Executor must have a StatefulExecutorBase", nameof(executor));
         }
 
-        /// <summary>
-        /// 
-        /// </summary>
-        /// <param name="path">The directory name to load the session.</param>
-        public virtual void LoadSession(string path)
+        Executor = executor;
+    }
+
+    /// <summary>
+    /// Create a new chat session with a custom history.
+    /// </summary>
+    /// <param name="executor"></param>
+    /// <param name="history"></param>
+    public ChatSession(ILLamaExecutor executor, ChatHistory history)
+        : this(executor)
+    {
+        History = history;
+    }
+
+    /// <summary>
+    /// Use a custom history transform.
+    /// </summary>
+    /// <param name="transform"></param>
+    /// <returns></returns>
+    public ChatSession WithHistoryTransform(IHistoryTransform transform)
+    {
+        HistoryTransform = transform;
+        return this;
+    }
+
+    /// <summary>
+    /// Add a text transform to the input transform pipeline.
+    /// </summary>
+    /// <param name="transform"></param>
+    /// <returns></returns>
+    public ChatSession AddInputTransform(ITextTransform transform)
+    {
+        InputTransformPipeline.Add(transform);
+        return this;
+    }
+
+    /// <summary>
+    /// Use a custom output transform.
+    /// </summary>
+    /// <param name="transform"></param>
+    /// <returns></returns>
+    public ChatSession WithOutputTransform(ITextStreamTransform transform)
+    {
+        OutputTransform = transform;
+        return this;
+    }
+
+    /// <summary>
+    /// Save a session from a directory.
+    /// </summary>
+    /// <param name="path"></param>
+    /// <returns></returns>
+    /// <exception cref="ArgumentException"></exception>
+    public void SaveSession(string path)
+    {
+        if (string.IsNullOrWhiteSpace(path))
         {
-            if (!Directory.Exists(path))
-            {
-                throw new FileNotFoundException($"Directory {path} does not exist.");
-            }
-            _executor.Context.LoadState(Path.Combine(path, _modelStateFilename));
-            if (Executor is StatelessExecutor)
-            {
+            throw new ArgumentException("Path cannot be null or whitespace", nameof(path));
+        }
 
-            }
-            else if (Executor is StatefulExecutorBase statefulExecutor)
-            {
-                statefulExecutor.LoadState(Path.Combine(path, _executorStateFilename));
-            }
-            else
-            {
-                throw new System.NotImplementedException("You're using a customized executor. Please inherit ChatSession and rewrite the method.");
-            }
+        if (Directory.Exists(path))
+        {
+            Directory.Delete(path, recursive: true);
         }
 
-        /// <summary>
-        /// Generates a response for a given user prompt and manages history state for the user.
-        /// This will always pass the whole history to the model. Don't pass a whole history
-        /// to this method as the user prompt will be appended to the history of the current session.
-        /// If more control is needed, use the other overload of this method that accepts a ChatHistory object.
-        /// </summary>
-        /// <param name="prompt"></param>
-        /// <param name="inferenceParams"></param>
-        /// <param name="cancellationToken"></param>
-        /// <returns>Returns generated text of the assistant message.</returns>
-        public async IAsyncEnumerable<string> ChatAsync(string prompt, IInferenceParams? inferenceParams = null, [EnumeratorCancellation] CancellationToken cancellationToken = default)
+        Directory.CreateDirectory(path);
+
+        string modelStateFilePath = Path.Combine(path, _modelStateFilename);
+        Executor.Context.SaveState(modelStateFilePath);
+
+        string executorStateFilepath = Path.Combine(path, _executorStateFilename);
+        ((StatefulExecutorBase)Executor).SaveState(executorStateFilepath);
+
+        string historyFilepath = Path.Combine(path, _hsitoryFilename);
+        File.WriteAllText(historyFilepath, History.ToJson());
+    }
+
+    /// <summary>
+    /// Load a session from a directory.
+    /// </summary>
+    /// <param name="path"></param>
+    /// <returns></returns>
+    /// <exception cref="ArgumentException"></exception>
+    public void LoadSession(string path)
+    {
+        if (string.IsNullOrWhiteSpace(path))
         {
-            foreach (var inputTransform in InputTransformPipeline)
-                prompt = inputTransform.Transform(prompt);
+            throw new ArgumentException("Path cannot be null or whitespace", nameof(path));
+        }
+
+        if (!Directory.Exists(path))
+        {
+            throw new ArgumentException("Directory does not exist", nameof(path));
+        }
+
+        string modelStateFilePath = Path.Combine(path, _modelStateFilename);
+        Executor.Context.LoadState(modelStateFilePath);
 
-            // TODO: need to be refactored.
-            if (_executor is InteractiveExecutor executor && ((InteractiveExecutorState)executor.GetStateData()).IsPromptRun)
+        string executorStateFilepath = Path.Combine(path, _executorStateFilename);
+        ((StatefulExecutorBase)Executor).LoadState(executorStateFilepath);
+
+        string historyFilepath = Path.Combine(path, _hsitoryFilename);
+        string historyJson = File.ReadAllText(historyFilepath);
+        History = ChatHistory.FromJson(historyJson)
+            ?? throw new ArgumentException("History file is invalid", nameof(path));
+    }
+
+    /// <summary>
+    /// Add a message to the chat history.
+    /// </summary>
+    /// <param name="message"></param>
+    /// <returns></returns>
+    public ChatSession AddMessage(ChatHistory.Message message)
+    {
+        // If current message is a system message, only allow the history to be empty
+        if (message.AuthorRole == AuthorRole.System && History.Messages.Count > 0)
+        {
+            throw new ArgumentException("Cannot add a system message after another message", nameof(message));
+        }
+
+        // If current message is a user message, only allow the history to be empty,
+        // or the previous message to be a system message or assistant message.
+        if (message.AuthorRole == AuthorRole.User)
+        {
+            ChatHistory.Message? lastMessage = History.Messages.LastOrDefault();
+            if (lastMessage is not null && lastMessage.AuthorRole == AuthorRole.User)
             {
-                History.Messages.Add(new ChatHistory.Message(AuthorRole.System, prompt));
-                var converted_prompt = HistoryTransform.HistoryToText(History);
-                // Avoid missing anti-prompt.
-                if (!prompt.EndsWith("\n") && !prompt.EndsWith("\r\n"))
-                {
-                    prompt = converted_prompt.Trim();
-                }
-                else
-                {
-                    prompt = converted_prompt;
-                }
+                throw new ArgumentException("Cannot add a user message after another user message", nameof(message));
             }
-            else
+        }
+
+        // If the current message is an assistant message,
+        // the previous message must be a user message.
+        if (message.AuthorRole == AuthorRole.Assistant)
+        {
+            ChatHistory.Message? lastMessage = History.Messages.LastOrDefault();
+            if (lastMessage is null
+                || lastMessage.AuthorRole != AuthorRole.User)
             {
-                History.Messages.Add(new ChatHistory.Message(AuthorRole.User, prompt));
+                throw new ArgumentException("Assistant message must be preceeded with a user message", nameof(message));
             }
+        }
+
+        History.AddMessage(message.AuthorRole, message.Content);
+        return this;
+    }
+
+    /// <summary>
+    /// Add a system message to the chat history.
+    /// </summary>
+    /// <param name="content"></param>
+    /// <returns></returns>
+    public ChatSession AddSystemMessage(string content)
+        => AddMessage(new ChatHistory.Message(AuthorRole.System, content));
+
+    /// <summary>
+    /// Add an assistant message to the chat history.
+    /// </summary>
+    /// <param name="content"></param>
+    /// <returns></returns>
+    public ChatSession AddAssistantMessage(string content)
+        => AddMessage(new ChatHistory.Message(AuthorRole.Assistant, content));
+
+    /// <summary>
+    /// Add a user message to the chat history.
+    /// </summary>
+    /// <param name="content"></param>
+    /// <returns></returns>
+    public ChatSession AddUserMessage(string content)
+        => AddMessage(new ChatHistory.Message(AuthorRole.User, content));
 
-            StringBuilder sb = new();
+    /// <summary>
+    /// Remove the last message from the chat history.
+    /// </summary>
+    /// <returns></returns>
+    public ChatSession RemoveLastMessage()
+    {
+        History.Messages.RemoveAt(History.Messages.Count - 1);
+        return this;
+    }
+
+    /// <summary>
+    /// Replace a user message with a new message and remove all messages after the new message.
+    /// This is useful when the user wants to edit a message. And regenerate the response.
+    /// </summary>
+    /// <param name="oldMessage"></param>
+    /// <param name="newMessage"></param>
+    /// <returns></returns>
+    public ChatSession ReplaceUserMessage(
+        ChatHistory.Message oldMessage,
+        ChatHistory.Message newMessage)
+    {
+        if (oldMessage.AuthorRole != AuthorRole.User)
+        {
+            throw new ArgumentException("Old message must be a user message", nameof(oldMessage));
+        }
 
-            await foreach (var result in ChatAsyncInternal(prompt, inferenceParams, cancellationToken))
+        if (newMessage.AuthorRole != AuthorRole.User)
+        {
+            throw new ArgumentException("New message must be a user message", nameof(newMessage));
+        }
+
+        int index = History.Messages.IndexOf(oldMessage);
+        if (index == -1)
+        {
+            throw new ArgumentException("Old message does not exist in history", nameof(oldMessage));
+        }
+
+        History.Messages[index] = newMessage;
+
+        // Remove all message after the new message
+        History.Messages.RemoveRange(index + 1, History.Messages.Count - index - 1);
+
+        return this;
+    }
+
+    /// <summary>
+    /// Chat with the model.
+    /// </summary>
+    /// <param name="message"></param>
+    /// <param name="inferenceParams"></param>
+    /// <param name="applyInputTransformPipeline"></param>
+    /// <param name="cancellationToken"></param>
+    /// <returns></returns>
+    /// <exception cref="ArgumentException"></exception>
+    public async IAsyncEnumerable<string> ChatAsync(
+        ChatHistory.Message message,
+        bool applyInputTransformPipeline,
+        IInferenceParams? inferenceParams = null,
+        [EnumeratorCancellation] CancellationToken cancellationToken = default)
+    {
+        // The message must be a user message
+        if (message.AuthorRole != AuthorRole.User)
+        {
+            throw new ArgumentException("Message must be a user message", nameof(message));
+        }
+
+        // Apply input transform pipeline
+        if (applyInputTransformPipeline)
+        {
+            foreach (var inputTransform in InputTransformPipeline)
             {
-                yield return result;
-                sb.Append(result);
+                message.Content = inputTransform.Transform(message.Content);
             }
+        }
+
+        // Add the user's message to the history
+        AddUserMessage(message.Content);
+
+        // Prepare prompt variable
+        string prompt;
+
+        // Check if the session history was restored from a previous session
+        // or added as part of new chat session history.
+        InteractiveExecutorState state = (InteractiveExecutorState)((StatefulExecutorBase)Executor).GetStateData();
+
+        // If "IsPromptRun" is true, the session was newly started.
+        if (state.IsPromptRun)
+        {
+            // If the session history was added as part of new chat session history,
+            // convert the complete history includsing system message and manually added history
+            // to a prompt that adhere to the prompt template specified in the HistoryTransform class implementation.
+            prompt = HistoryTransform.HistoryToText(History);
+        }
+        else
+        {
+            // If the session was restored from a previous session,
+            // convert only the current message to the prompt with the prompt template
+            // specified in the HistoryTransform class implementation that is provided.
+            ChatHistory singleMessageHistory = HistoryTransform.TextToHistory(message.AuthorRole, message.Content);
+            prompt = HistoryTransform.HistoryToText(singleMessageHistory);
+        }
+
+        string assistantMessage = string.Empty;
+
+        await foreach (
+            string textToken
+            in ChatAsyncInternal(
+                prompt,
+                inferenceParams,
+                cancellationToken))
+        {
+            assistantMessage += textToken;
+            yield return textToken;
+        }
+
+        // Add the assistant message to the history
+        AddAssistantMessage(assistantMessage);
+    }
+
+    /// <summary>
+    /// Chat with the model.
+    /// </summary>
+    /// <param name="message"></param>
+    /// <param name="inferenceParams"></param>
+    /// <param name="cancellationToken"></param>
+    /// <returns></returns>
+    public IAsyncEnumerable<string> ChatAsync(
+        ChatHistory.Message message,
+        IInferenceParams? inferenceParams = null,
+        CancellationToken cancellationToken = default)
+    {
+        return ChatAsync(
+            message,
+            applyInputTransformPipeline: true,
+            inferenceParams,
+            cancellationToken);
+    }
 
-            string assistantMessage = sb.ToString();
+    /// <summary>
+    /// Chat with the model.
+    /// </summary>
+    /// <param name="history"></param>
+    /// <param name="applyInputTransformPipeline"></param>
+    /// <param name="inferenceParams"></param>
+    /// <param name="cancellationToken"></param>
+    /// <returns></returns>
+    /// <exception cref="ArgumentException"></exception>
+    public IAsyncEnumerable<string> ChatAsync(
+        ChatHistory history,
+        bool applyInputTransformPipeline,
+        IInferenceParams? inferenceParams = null,
+        CancellationToken cancellationToken = default)
+    {
+        ChatHistory.Message lastMessage = history.Messages.LastOrDefault()
+            ?? throw new ArgumentException("History must contain at least one message", nameof(history));
 
-            // Remove end tokens from the assistant message
-            // if defined in inferenceParams.AntiPrompts.
-            // We only want the response that was generated and not tokens
-            // that are delimiting the beginning or end of the response.
-            if (inferenceParams?.AntiPrompts != null)
+        foreach (
+            ChatHistory.Message message
+            in history.Messages.Take(history.Messages.Count - 1))
+        {
+            // Apply input transform pipeline
+            if (applyInputTransformPipeline
+                && message.AuthorRole == AuthorRole.User)
             {
-                foreach (var stopToken in inferenceParams.AntiPrompts)
+                foreach (
+                    var inputTransform
+                    in InputTransformPipeline)
                 {
-                    assistantMessage = assistantMessage.Replace(stopToken, "");
+                    message.Content = inputTransform.Transform(message.Content);
                 }
             }
 
-            History.Messages.Add(new ChatHistory.Message(AuthorRole.Assistant, assistantMessage));
+            AddMessage(message);
         }
 
-        /// <summary>
-        /// Generates a response for a given chat history. This method does not manage history state for the user.
-        /// If you want to e.g. truncate the history of a session to fit into the model's context window,
-        /// use this method and pass the truncated history to it. If you don't need this control, use the other
-        /// overload of this method that accepts a user prompt instead.
-        /// </summary>
-        /// <param name="history"></param>
-        /// <param name="inferenceParams"></param>
-        /// <param name="cancellationToken"></param>
-        /// <returns>Returns generated text of the assistant message.</returns>
-        public async IAsyncEnumerable<string> ChatAsync(ChatHistory history, IInferenceParams? inferenceParams = null, [EnumeratorCancellation] CancellationToken cancellationToken = default)
+        return ChatAsync(
+            lastMessage,
+            applyInputTransformPipeline,
+            inferenceParams,
+            cancellationToken);
+    }
+
+    /// <summary>
+    /// Chat with the model.
+    /// </summary>
+    /// <param name="history"></param>
+    /// <param name="inferenceParams"></param>
+    /// <param name="cancellationToken"></param>
+    /// <returns></returns>
+    public IAsyncEnumerable<string> ChatAsync(
+        ChatHistory history,
+        IInferenceParams? inferenceParams = null,
+        CancellationToken cancellationToken = default)
+    {
+        return ChatAsync(
+            history,
+            applyInputTransformPipeline: true,
+            inferenceParams,
+            cancellationToken);
+    }
+
+    /// <summary>
+    /// Regenerate the last assistant message.
+    /// </summary>
+    /// <param name="inferenceParams"></param>
+    /// <param name="cancellationToken"></param>
+    /// <returns></returns>
+    /// <exception cref="InvalidOperationException"></exception>
+    public async IAsyncEnumerable<string> RegenerateAssistantMessageAsync(
+        InferenceParams? inferenceParams = null,
+        [EnumeratorCancellation] CancellationToken cancellationToken = default)
+    {
+        // Make sure the last message is an assistant message (reponse from the LLM).
+        ChatHistory.Message? lastAssistantMessage = History.Messages.LastOrDefault();
+
+        if (lastAssistantMessage is null
+            || lastAssistantMessage.AuthorRole != AuthorRole.Assistant)
         {
-            if (history.Messages.Count == 0)
-            {
-                throw new ArgumentException("History must contain at least one message.");
-            }
+            throw new InvalidOperationException("Last message must be an assistant message");
+        }
 
-            string prompt;
-            if (_executor is InteractiveExecutor executor)
-            {
-                InteractiveExecutorState state = (InteractiveExecutorState)executor.GetStateData();
+        // Remove the last assistant message from the history.
+        RemoveLastMessage();
 
-                prompt = state.IsPromptRun
-                    ? HistoryTransform.HistoryToText(History)
-                    : history.Messages.Last().Content;
-            }
-            else
-            {
-                prompt = history.Messages.Last().Content;
-            }
+        // Get the last user message.
+        ChatHistory.Message? lastUserMessage = History.Messages.LastOrDefault();
 
-            await foreach (var result in ChatAsyncInternal(prompt, inferenceParams, cancellationToken))
-            {
-                yield return result;
-            }
+        if (lastUserMessage is null
+            || lastUserMessage.AuthorRole != AuthorRole.User)
+        {
+            throw new InvalidOperationException("Last message must be a user message");
         }
 
-        private async IAsyncEnumerable<string> ChatAsyncInternal(string prompt, IInferenceParams? inferenceParams = null, [EnumeratorCancellation] CancellationToken cancellationToken = default)
+        // Remove the last user message from the history.
+        RemoveLastMessage();
+
+        // Regenerate the assistant message.
+        await foreach (
+            string textToken
+            in ChatAsync(
+                lastUserMessage,
+                applyInputTransformPipeline: false,
+                inferenceParams,
+                cancellationToken))
         {
-            var results = _executor.InferAsync(prompt, inferenceParams, cancellationToken);
-            await foreach (var item in OutputTransform.TransformAsync(results).WithCancellation(cancellationToken))
-            {
-                yield return item;
-            }
+            yield return textToken;
+        }
+    }
+
+    private async IAsyncEnumerable<string> ChatAsyncInternal(
+        string prompt,
+        IInferenceParams? inferenceParams = null,
+        [EnumeratorCancellation] CancellationToken cancellationToken = default)
+    {
+        var results = Executor.InferAsync(prompt, inferenceParams, cancellationToken);
+
+        await foreach (
+            string textToken
+            in OutputTransform
+                .TransformAsync(results)
+                .WithCancellation(cancellationToken))
+        {
+            yield return textToken;
         }
     }
-}
+}

LLama/Common/ChatHistory.cs

@@ -1,4 +1,7 @@
 using System.Collections.Generic;
+using System.IO;
+using System.Text.Json;
+using System.Text.Json.Serialization;
 
 namespace LLama.Common
 {
@@ -43,11 +46,14 @@ namespace LLama.Common
             /// <summary>
             /// Role of the message author, e.g. user/assistant/system
             /// </summary>
+            [JsonConverter(typeof(JsonStringEnumConverter))]
+            [JsonPropertyName("author_role")]
             public AuthorRole AuthorRole { get; set; }
 
             /// <summary>
             /// Message content
             /// </summary>
+            [JsonPropertyName("content")]
             public string Content { get; set; }
 
             /// <summary>
@@ -65,15 +71,14 @@ namespace LLama.Common
         /// <summary>
         /// List of messages in the chat
         /// </summary>
-        public List<Message> Messages { get; }
+        [JsonPropertyName("messages")]
+        public List<Message> Messages { get; set; } = new();
 
         /// <summary>
         /// Create a new instance of the chat content class
         /// </summary>
-        public ChatHistory()
-        {
-            this.Messages = new List<Message>();
-        }
+        [JsonConstructor]
+        public ChatHistory() { }
 
         /// <summary>
         /// Add a message to the chat history
@@ -84,6 +89,29 @@ namespace LLama.Common
         {
             this.Messages.Add(new Message(authorRole, content));
         }
-    }
 
+        /// <summary>
+        /// Serialize the chat history to JSON
+        /// </summary>
+        /// <returns></returns>
+        public string ToJson()
+        {
+            return JsonSerializer.Serialize(
+                this,
+                new JsonSerializerOptions()
+                {
+                    WriteIndented = true
+                });
+        }
+
+        /// <summary>
+        /// Deserialize a chat history from JSON
+        /// </summary>
+        /// <param name="json"></param>
+        /// <returns></returns>
+        public static ChatHistory? FromJson(string json)
+        {
+            return JsonSerializer.Deserialize<ChatHistory>(json);
+        }
+    }
 }

LLama/LLamaSharp.csproj

@@ -28,6 +28,7 @@
     <Platforms>AnyCPU;x64;Arm64</Platforms>
     <PackageId>LLamaSharp</PackageId>
     <Configurations>Debug;Release;GPU</Configurations>
+    <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
   </PropertyGroup>
 
   <PropertyGroup>