.NET: Rename ChatMessageStore to ChatHistoryProvider (#3375)

* Rename ChatMessageStore to ChatHistoryProvider

* Fix merge issue

* Fixed PR comments

* Fix tests after property rename

* Add unit tests and fix merge issues

* Fix encoding

dotnet/src/Microsoft.Agents.AI.Abstractions/InMemoryAgentThread.cs

@@ -9,11 +9,11 @@ using Microsoft.Extensions.AI;
 namespace Microsoft.Agents.AI;
 
 /// <summary>
-/// Provides an abstract base class for agent threads that maintain all conversation state in local memory.
+/// Provides an abstract base class for an <see cref="AgentThread"/> that maintain all chat history in local memory.
 /// </summary>
 /// <remarks>
 /// <para>
-/// <see cref="InMemoryAgentThread"/> is designed for scenarios where conversation state should be stored locally
+/// <see cref="InMemoryAgentThread"/> is designed for scenarios where chat history should be stored locally
 /// rather than in external services or databases. This approach provides high performance and simplicity while
 /// maintaining full control over the conversation data.
 /// </para>
@@ -28,17 +28,17 @@ public abstract class InMemoryAgentThread : AgentThread
     /// <summary>
     /// Initializes a new instance of the <see cref="InMemoryAgentThread"/> class.
     /// </summary>
-    /// <param name="messageStore">
-    /// An optional <see cref="InMemoryChatMessageStore"/> instance to use for storing chat messages.
-    /// If <see langword="null"/>, a new empty message store will be created.
+    /// <param name="chatHistoryProvider">
+    /// An optional <see cref="InMemoryChatHistoryProvider"/> instance to use for storing chat messages.
+    /// If <see langword="null"/>, a new empty <see cref="InMemoryChatHistoryProvider"/> will be created.
     /// </param>
     /// <remarks>
-    /// This constructor allows sharing of message stores between threads or providing pre-configured
-    /// message stores with specific reduction or processing logic.
+    /// This constructor allows sharing of <see cref="ChatHistoryProvider"/> between threads or providing pre-configured
+    /// <see cref="ChatHistoryProvider"/> with specific reduction or processing logic.
     /// </remarks>
-    protected InMemoryAgentThread(InMemoryChatMessageStore? messageStore = null)
+    protected InMemoryAgentThread(InMemoryChatHistoryProvider? chatHistoryProvider = null)
     {
-        this.MessageStore = messageStore ?? [];
+        this.ChatHistoryProvider = chatHistoryProvider ?? [];
     }
 
     /// <summary>
@@ -52,7 +52,7 @@ public abstract class InMemoryAgentThread : AgentThread
     /// </remarks>
     protected InMemoryAgentThread(IEnumerable<ChatMessage> messages)
     {
-        this.MessageStore = [.. messages];
+        this.ChatHistoryProvider = [.. messages];
     }
 
     /// <summary>
@@ -60,9 +60,9 @@ public abstract class InMemoryAgentThread : AgentThread
     /// </summary>
     /// <param name="serializedThreadState">A <see cref="JsonElement"/> representing the serialized state of the thread.</param>
     /// <param name="jsonSerializerOptions">Optional settings for customizing the JSON deserialization process.</param>
-    /// <param name="messageStoreFactory">
-    /// Optional factory function to create the <see cref="InMemoryChatMessageStore"/> from its serialized state.
-    /// If not provided, a default factory will be used that creates a basic in-memory store.
+    /// <param name="chatHistoryProviderFactory">
+    /// Optional factory function to create the <see cref="InMemoryChatHistoryProvider"/> from its serialized state.
+    /// If not provided, a default factory will be used that creates a basic <see cref="InMemoryChatHistoryProvider"/>.
     /// </param>
     /// <exception cref="ArgumentException">The <paramref name="serializedThreadState"/> is not a JSON object.</exception>
     /// <exception cref="JsonException">The <paramref name="serializedThreadState"/> is invalid or cannot be deserialized to the expected type.</exception>
@@ -73,7 +73,7 @@ public abstract class InMemoryAgentThread : AgentThread
     protected InMemoryAgentThread(
         JsonElement serializedThreadState,
         JsonSerializerOptions? jsonSerializerOptions = null,
-        Func<JsonElement, JsonSerializerOptions?, InMemoryChatMessageStore>? messageStoreFactory = null)
+        Func<JsonElement, JsonSerializerOptions?, InMemoryChatHistoryProvider>? chatHistoryProviderFactory = null)
     {
         if (serializedThreadState.ValueKind != JsonValueKind.Object)
         {
@@ -83,15 +83,15 @@ public abstract class InMemoryAgentThread : AgentThread
         var state = serializedThreadState.Deserialize(
             AgentAbstractionsJsonUtilities.DefaultOptions.GetTypeInfo(typeof(InMemoryAgentThreadState))) as InMemoryAgentThreadState;
 
-        this.MessageStore =
-            messageStoreFactory?.Invoke(state?.StoreState ?? default, jsonSerializerOptions) ??
-            new InMemoryChatMessageStore(state?.StoreState ?? default, jsonSerializerOptions);
+        this.ChatHistoryProvider =
+            chatHistoryProviderFactory?.Invoke(state?.ChatHistoryProviderState ?? default, jsonSerializerOptions) ??
+            new InMemoryChatHistoryProvider(state?.ChatHistoryProviderState ?? default, jsonSerializerOptions);
     }
 
     /// <summary>
-    /// Gets or sets the <see cref="InMemoryChatMessageStore"/> used by this thread.
+    /// Gets or sets the <see cref="InMemoryChatHistoryProvider"/> used by this thread.
     /// </summary>
-    public InMemoryChatMessageStore MessageStore { get; }
+    public InMemoryChatHistoryProvider ChatHistoryProvider { get; }
 
     /// <summary>
     /// Serializes the current object's state to a <see cref="JsonElement"/> using the specified serialization options.
@@ -100,11 +100,11 @@ public abstract class InMemoryAgentThread : AgentThread
     /// <returns>A <see cref="JsonElement"/> representation of the object's state.</returns>
     public override JsonElement Serialize(JsonSerializerOptions? jsonSerializerOptions = null)
     {
-        var storeState = this.MessageStore.Serialize(jsonSerializerOptions);
+        var chatHistoryProviderState = this.ChatHistoryProvider.Serialize(jsonSerializerOptions);
 
         var state = new InMemoryAgentThreadState
         {
-            StoreState = storeState,
+            ChatHistoryProviderState = chatHistoryProviderState,
         };
 
         return JsonSerializer.SerializeToElement(state, AgentAbstractionsJsonUtilities.DefaultOptions.GetTypeInfo(typeof(InMemoryAgentThreadState)));
@@ -112,13 +112,13 @@ public abstract class InMemoryAgentThread : AgentThread
 
     /// <inheritdoc/>
     public override object? GetService(Type serviceType, object? serviceKey = null) =>
-        base.GetService(serviceType, serviceKey) ?? this.MessageStore?.GetService(serviceType, serviceKey);
+        base.GetService(serviceType, serviceKey) ?? this.ChatHistoryProvider?.GetService(serviceType, serviceKey);
 
     [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-    private string DebuggerDisplay => $"Count = {this.MessageStore.Count}";
+    private string DebuggerDisplay => $"Count = {this.ChatHistoryProvider.Count}";
 
     internal sealed class InMemoryAgentThreadState
     {
-        public JsonElement? StoreState { get; set; }
+        public JsonElement? ChatHistoryProviderState { get; set; }
     }
 }