ability to rewind chat history; improve handling of chat history (streaming)

Author: jochenkirstaetter

src/Mscc.GenerativeAI/CHANGELOG.md

@@ -7,13 +7,22 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+### Changed
+### Fixed
+
+## 0.8.2
+
 ### Added
 
+- ability to rewind chat history
 - provide types to simplify creation of tuned model
 - compatibility methods for PaLM models
+- access text of content response easier
 
 ### Changed
-### Fixed
+
+- improve handling of chat history (streaming)
 
 ## 0.8.1
 

src/Mscc.GenerativeAI/Types/ChatSession.cs

@@ -6,23 +6,40 @@
 using System.Threading.Tasks;
 #endif
 using System.Runtime.CompilerServices;
+using System.Text;
 
 namespace Mscc.GenerativeAI
 {
+    /// <summary>
+    /// This ChatSession object collects the messages sent and received, in its ChatSession.History attribute.
+    /// </summary>
     public class ChatSession
     {
         private readonly GenerativeModel _model;
         private readonly GenerationConfig? _generationConfig;
         private readonly List<SafetySetting>? _safetySettings;
         private readonly List<Tool>? _tools;
+        private ContentResponse? _lastSent;
+        private ContentResponse? _lastReceived;
 
+        /// <summary>
+        /// The chat history.
+        /// </summary>
         public List<ContentResponse> History { get; set; }
 
         /// <summary>
-        /// 
+        /// Returns the last received ContentResponse
+        /// </summary>
+        public ContentResponse? Last => _lastReceived;
+
+        /// <summary>
+        /// Constructor to start a chat session with history.
         /// </summary>
         /// <param name="model"></param>
         /// <param name="history"></param>
+        /// <param name="generationConfig">Optional. Configuration options for model generation and outputs.</param>
+        /// <param name="safetySettings">Optional. A list of unique SafetySetting instances for blocking unsafe content.</param>
+        /// <param name="tools">Optional. </param>
         public ChatSession(GenerativeModel model,
             List<ContentResponse>? history = null,
             GenerationConfig? generationConfig = null,
@@ -37,38 +54,55 @@ public ChatSession(GenerativeModel model,
         }
 
         /// <summary>
-        /// 
+        /// Sends the conversation history with the added message and returns the model's response.
+        /// Appends the request and response to the conversation history.
         /// </summary>
         /// <param name="prompt"></param>
+        /// <param name="generationConfig">Optional. Overrides for the model's generation config.</param>
+        /// <param name="safetySettings">Optional. Overrides for the model's safety settings.</param>
         /// <returns></returns>
-        public async Task<GenerateContentResponse> SendMessage(string prompt)
+        public async Task<GenerateContentResponse> SendMessage(string prompt,
+            GenerationConfig? generationConfig = null,
+            List<SafetySetting>? safetySettings = null)
         {
             if (prompt == null) throw new ArgumentNullException(nameof(prompt));
             if (string.IsNullOrEmpty(prompt)) throw new ArgumentException(prompt, nameof(prompt));
 
-            History.Add(new ContentResponse { Role = Role.User, Parts = new List<Part> { new Part { Text = prompt } } });
+            _lastSent = new ContentResponse
+            {
+                Role = Role.User, Parts = new List<Part> { new Part { Text = prompt } }
+            };
+            History.Add(_lastSent);
             var request = new GenerateContentRequest
             {
                 Contents = History.Select(x =>
                     new Content { Role = x.Role, PartTypes = x.Parts }
                 ).ToList(),
-                GenerationConfig = _generationConfig,
-                SafetySettings = _safetySettings,
+                GenerationConfig = generationConfig ?? _generationConfig,
+                SafetySettings = safetySettings ?? _safetySettings,
                 Tools = _tools
             };
 
             var response = await _model.GenerateContent(request);
-            History.Add(new ContentResponse { Role = Role.Model, Parts = new List<Part> { new Part { Text = response.Text } } });
+            _lastReceived = new ContentResponse
+            {
+                Role = Role.Model, Parts = new List<Part> { new Part { Text = response.Text ?? string.Empty } }
+            };
+            History.Add(_lastReceived);
             return response;
         }
 
         /// <summary>
         /// 
         /// </summary>
         /// <param name="content"></param>
+        /// <param name="generationConfig">Optional. Overrides for the model's generation config.</param>
+        /// <param name="safetySettings">Optional. Overrides for the model's safety settings.</param>
         /// <param name="cancellationToken"></param>
         /// <returns></returns>
-        public async IAsyncEnumerable<GenerateContentResponse> SendMessageStream(object content, 
+        public async IAsyncEnumerable<GenerateContentResponse> SendMessageStream(object content,
+            GenerationConfig? generationConfig = null,
+            List<SafetySetting>? safetySettings = null, 
             [EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
             if (content == null) throw new ArgumentNullException(nameof(content));
@@ -87,25 +121,60 @@ public async IAsyncEnumerable<GenerateContentResponse> SendMessageStream(object
                 parts = contentParts;
             }
 
-            History.Add(new ContentResponse { Role = role, Parts = parts });
+            _lastSent = new ContentResponse
+            {
+                Role = role, Parts = parts
+            };
+            History.Add(_lastSent);
             var request = new GenerateContentRequest
             {
                 Contents = History.Select(x => 
                     new Content { Role = x.Role, PartTypes = x.Parts }
                 ).ToList(),
-                GenerationConfig = _generationConfig,
-                SafetySettings = _safetySettings,
+                GenerationConfig = generationConfig ?? _generationConfig,
+                SafetySettings = safetySettings ?? _safetySettings,
                 Tools = _tools
             };
 
+            var fullText = new StringBuilder();
             var response = _model.GenerateContentStream(request, cancellationToken);
             await foreach (var item in response)
             {
                 if (cancellationToken.IsCancellationRequested)
                     yield break;
-                History.Add(new ContentResponse { Role = Role.Model, Parts = item?.Candidates?[0]?.Content?.Parts });
+                fullText.Append(item.Text);
                 yield return item;
             }
+            _lastReceived = new ContentResponse
+            {
+                Role = Role.Model, Parts = new List<Part> { new Part { Text = fullText.ToString() } }
+            };
+            History.Add(_lastReceived);
+        }
+
+        /// <summary>
+        /// Removes the last request/response pair from the chat history.
+        /// </summary>
+        /// <returns>Tuple with the last request/response pair.</returns>
+        public (ContentResponse? Sent, ContentResponse? Received) Rewind()
+        {
+            (ContentResponse? Sent, ContentResponse? Received) result;
+            var position = History.Count - 2;
+
+            if (_lastReceived is null)
+            {
+                var entries = History.GetRange(position, 2);
+                result = (entries.FirstOrDefault(), entries.LastOrDefault());
+            }
+            else
+            {
+                result = (_lastSent, _lastReceived);
+                _lastSent = null;
+                _lastReceived = null;
+            }
+
+            History.RemoveRange(position, 2);
+            return result;
         }
     }
 }

tests/Mscc.GenerativeAI/GoogleAi_GeminiPro_Should.cs

@@ -458,10 +458,66 @@ public async void Start_Chat_Conversations()
             chat.History.ForEach(c =>
             {
                 output.WriteLine($"{new string('-', 20)}");
-                output.WriteLine($"{c.Role}: {c.Parts[0].Text}");
+                output.WriteLine($"{c.Role}: {c.Text}");
             });
         }
 
+        [Fact]
+        // Refs:
+        // https://ai.google.dev/tutorials/python_quickstart#chat_conversations
+        public async void Start_Chat_Rewind_Conversation()
+        {
+            // Arrange
+            var model = new GenerativeModel(apiKey: fixture.ApiKey, model: this.model);
+            var chat = model.StartChat();
+            _ = await chat.SendMessage("Hello, fancy brainstorming about IT?");
+            _ = await chat.SendMessage("In one sentence, explain how a computer works to a young child.");
+            _ = await chat.SendMessage("Okay, how about a more detailed explanation to a high school kid?");
+            _ = await chat.SendMessage("Lastly, give a thorough definition for a CS graduate.");
+
+            // Act
+            var entries = chat.Rewind();
+
+            // Assert
+            entries.Should().NotBeNull();
+            entries.Sent.Should().NotBeNull();
+            entries.Received.Should().NotBeNull();
+            output.WriteLine("------ Rewind ------");
+            output.WriteLine($"{entries.Sent.Role}: {entries.Sent.Text}");
+            output.WriteLine($"{new string('-', 20)}");
+            output.WriteLine($"{entries.Received.Role}: {entries.Received.Text}");
+            output.WriteLine($"{new string('-', 20)}");
+            
+            chat.History.Count.Should().Be(6);
+            output.WriteLine("------ History -----");
+            chat.History.ForEach(c =>
+            {
+                output.WriteLine($"{new string('-', 20)}");
+                output.WriteLine($"{c.Role}: {c.Text}");
+            });
+        }
+
+        [Fact]
+        // Refs:
+        // https://ai.google.dev/tutorials/python_quickstart#chat_conversations
+        public async void Start_Chat_Conversations_Get_Last()
+        {
+            // Arrange
+            var model = new GenerativeModel(apiKey: fixture.ApiKey, model: this.model);
+            var chat = model.StartChat();
+            _ = await chat.SendMessage("Hello, fancy brainstorming about IT?");
+            _ = await chat.SendMessage("In one sentence, explain how a computer works to a young child.");
+            _ = await chat.SendMessage("Okay, how about a more detailed explanation to a high school kid?");
+            _ = await chat.SendMessage("Lastly, give a thorough definition for a CS graduate.");
+
+            // Act
+            var sut = chat.Last;
+
+            // Assert
+            sut.Should().NotBeNull();
+            output.WriteLine($"{sut.Role}: {sut.Text}");
+        }
+
         [Fact]
         public async void Start_Chat_Streaming()
         {
@@ -486,6 +542,14 @@ public async void Start_Chat_Streaming()
                 // output.WriteLine($"CandidatesTokenCount: {response?.UsageMetadata?.CandidatesTokenCount}");
                 // output.WriteLine($"TotalTokenCount: {response?.UsageMetadata?.TotalTokenCount}");
             }
+            chat.History.Count.Should().Be(2);
+            output.WriteLine($"{new string('-', 20)}");
+            output.WriteLine("------ History -----");
+            chat.History.ForEach(c =>
+            {
+                output.WriteLine($"{new string('-', 20)}");
+                output.WriteLine($"{c.Role}: {c.Text}");
+            });
         }
 
         [Fact]