.NET: Add ability to mark the source of Agent request messages and use that for filtering

dotnet/samples/GettingStarted/AgentProviders/Agent_With_CustomImplementation/Program.cs

@@ -52,7 +52,7 @@ protected override async Task<AgentResponse> RunCoreAsync(IEnumerable<ChatMessag
             List<ChatMessage> responseMessages = CloneAndToUpperCase(messages, this.Name).ToList();
 
             // Notify the session of the input and output messages.
-            var invokedContext = new ChatHistoryProvider.InvokedContext(messages, storeMessages)
+            var invokedContext = new ChatHistoryProvider.InvokedContext(messages)
             {
                 ResponseMessages = responseMessages
             };
@@ -84,7 +84,7 @@ protected override async IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingA
             List<ChatMessage> responseMessages = CloneAndToUpperCase(messages, this.Name).ToList();
 
             // Notify the session of the input and output messages.
-            var invokedContext = new ChatHistoryProvider.InvokedContext(messages, storeMessages)
+            var invokedContext = new ChatHistoryProvider.InvokedContext(messages)
             {
                 ResponseMessages = responseMessages
             };

dotnet/samples/GettingStarted/AgentWithMemory/AgentWithMemory_Step03_CustomMemory/Program.cs

@@ -104,7 +104,7 @@ public UserInfoMemory(IChatClient chatClient, JsonElement serializedState, JsonS
 
         public UserInfo UserInfo { get; set; }
 
-        public override async ValueTask InvokedAsync(InvokedContext context, CancellationToken cancellationToken = default)
+        protected override async ValueTask InvokedCoreAsync(InvokedContext context, CancellationToken cancellationToken = default)
         {
             // Try and extract the user name and age from the message if we don't have it already and it's a user message.
             if ((this.UserInfo.UserName is null || this.UserInfo.UserAge is null) && context.RequestMessages.Any(x => x.Role == ChatRole.User))
@@ -122,7 +122,7 @@ public override async ValueTask InvokedAsync(InvokedContext context, Cancellatio
             }
         }
 
-        public override ValueTask<AIContext> InvokingAsync(InvokingContext context, CancellationToken cancellationToken = default)
+        protected override ValueTask<AIContext> InvokingCoreAsync(InvokingContext context, CancellationToken cancellationToken = default)
         {
             StringBuilder instructions = new();
 

dotnet/samples/GettingStarted/Agents/Agent_Step07_3rdPartyThreadStorage/Program.cs

@@ -87,7 +87,7 @@ public VectorChatHistoryProvider(VectorStore vectorStore, JsonElement serialized
 
         public string? SessionDbKey { get; private set; }
 
-        public override async ValueTask<IEnumerable<ChatMessage>> InvokingAsync(InvokingContext context, CancellationToken cancellationToken = default)
+        protected override async ValueTask<IEnumerable<ChatMessage>> InvokingCoreAsync(InvokingContext context, CancellationToken cancellationToken = default)
         {
             var collection = this._vectorStore.GetCollection<string, ChatHistoryItem>("ChatHistory");
             await collection.EnsureCollectionExistsAsync(cancellationToken);
@@ -105,7 +105,7 @@ public override async ValueTask<IEnumerable<ChatMessage>> InvokingAsync(Invoking
             return messages;
         }
 
-        public override async ValueTask InvokedAsync(InvokedContext context, CancellationToken cancellationToken = default)
+        protected override async ValueTask InvokedCoreAsync(InvokedContext context, CancellationToken cancellationToken = default)
         {
             // Don't store messages if the request failed.
             if (context.InvokeException is not null)
@@ -120,7 +120,7 @@ public override async ValueTask InvokedAsync(InvokedContext context, Cancellatio
 
             // Add both request and response messages to the store
             // Optionally messages produced by the AIContextProvider can also be persisted (not shown).
-            var allNewMessages = context.RequestMessages.Concat(context.AIContextProviderMessages ?? []).Concat(context.ResponseMessages ?? []);
+            var allNewMessages = context.RequestMessages.Concat(context.ResponseMessages ?? []);
 
             await collection.UpsertAsync(allNewMessages.Select(x => new ChatHistoryItem()
             {

dotnet/samples/GettingStarted/Agents/Agent_Step20_AdditionalAIContext/Program.cs

@@ -92,7 +92,7 @@ public TodoListAIContextProvider(JsonElement jsonElement, JsonSerializerOptions?
             }
         }
 
-        public override ValueTask<AIContext> InvokingAsync(InvokingContext context, CancellationToken cancellationToken = default)
+        protected override ValueTask<AIContext> InvokingCoreAsync(InvokingContext context, CancellationToken cancellationToken = default)
         {
             StringBuilder outputMessageBuilder = new();
             outputMessageBuilder.AppendLine("Your todo list contains the following items:");
@@ -132,7 +132,7 @@ public override JsonElement Serialize(JsonSerializerOptions? jsonSerializerOptio
     /// </summary>
     internal sealed class CalendarSearchAIContextProvider(Func<Task<string[]>> loadNextThreeCalendarEvents) : AIContextProvider
     {
-        public override async ValueTask<AIContext> InvokingAsync(InvokingContext context, CancellationToken cancellationToken = default)
+        protected override async ValueTask<AIContext> InvokingCoreAsync(InvokingContext context, CancellationToken cancellationToken = default)
         {
             var events = await loadNextThreeCalendarEvents();
 
@@ -179,7 +179,7 @@ public AggregatingAIContextProvider(ProviderFactory[] providerFactories, JsonEle
                 .ToList();
         }
 
-        public override async ValueTask<AIContext> InvokingAsync(InvokingContext context, CancellationToken cancellationToken = default)
+        protected override async ValueTask<AIContext> InvokingCoreAsync(InvokingContext context, CancellationToken cancellationToken = default)
         {
             // Invoke all the sub providers.
             var tasks = this._providers.Select(provider => provider.InvokingAsync(context, cancellationToken).AsTask());

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

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
@@ -48,7 +49,51 @@ public abstract class AIContextProvider
     /// </list>
     /// </para>
     /// </remarks>
-    public abstract ValueTask<AIContext> InvokingAsync(InvokingContext context, CancellationToken cancellationToken = default);
+    public async ValueTask<AIContext> InvokingAsync(InvokingContext context, CancellationToken cancellationToken = default)
+    {
+        var aiContext = await this.InvokingCoreAsync(context, cancellationToken).ConfigureAwait(false);
+        if (aiContext.Messages is null)
+        {
+            return aiContext;
+        }
+
+        aiContext.Messages = aiContext.Messages.Select(message =>
+        {
+            if (message.AdditionalProperties != null
+                && message.AdditionalProperties.TryGetValue(AgentRequestMessageSource.AdditionalPropertiesKey, out var source)
+                && source is AgentRequestMessageSource typedSource
+                && typedSource == AgentRequestMessageSource.AIContextProvider)
+            {
+                return message;
+            }
+
+            message = message.Clone();
+            message.AdditionalProperties ??= new();
+            message.AdditionalProperties[AgentRequestMessageSource.AdditionalPropertiesKey] = AgentRequestMessageSource.AIContextProvider;
+            return message;
+        }).ToList();
+
+        return aiContext;
+    }
+
+    /// <summary>
+    /// Called at the start of agent invocation to provide additional context.
+    /// </summary>
+    /// <param name="context">Contains the request context including the caller provided messages that will be used by the agent for this invocation.</param>
+    /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
+    /// <returns>A task that represents the asynchronous operation. The task result contains the <see cref="AIContext"/> with additional context to be used by the agent during this invocation.</returns>
+    /// <remarks>
+    /// <para>
+    /// Implementers can load any additional context required at this time, such as:
+    /// <list type="bullet">
+    /// <item><description>Retrieving relevant information from knowledge bases</description></item>
+    /// <item><description>Adding system instructions or prompts</description></item>
+    /// <item><description>Providing function tools for the current invocation</description></item>
+    /// <item><description>Injecting contextual messages from conversation history</description></item>
+    /// </list>
+    /// </para>
+    /// </remarks>
+    protected abstract ValueTask<AIContext> InvokingCoreAsync(InvokingContext context, CancellationToken cancellationToken = default);
 
     /// <summary>
     /// Called at the end of the agent invocation to process the invocation results.
@@ -71,7 +116,31 @@ public abstract class AIContextProvider
     /// To check if the invocation was successful, inspect the <see cref="InvokedContext.InvokeException"/> property.
     /// </para>
     /// </remarks>
-    public virtual ValueTask InvokedAsync(InvokedContext context, CancellationToken cancellationToken = default)
+    public ValueTask InvokedAsync(InvokedContext context, CancellationToken cancellationToken = default)
+        => this.InvokedCoreAsync(context, cancellationToken);
+
+    /// <summary>
+    /// Called at the end of the agent invocation to process the invocation results.
+    /// </summary>
+    /// <param name="context">Contains the invocation context including request messages, response messages, and any exception that occurred.</param>
+    /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    /// <remarks>
+    /// <para>
+    /// Implementers can use the request and response messages in the provided <paramref name="context"/> to:
+    /// <list type="bullet">
+    /// <item><description>Update internal state based on conversation outcomes</description></item>
+    /// <item><description>Extract and store memories or preferences from user messages</description></item>
+    /// <item><description>Log or audit conversation details</description></item>
+    /// <item><description>Perform cleanup or finalization tasks</description></item>
+    /// </list>
+    /// </para>
+    /// <para>
+    /// This method is called regardless of whether the invocation succeeded or failed.
+    /// To check if the invocation was successful, inspect the <see cref="InvokedContext.InvokeException"/> property.
+    /// </para>
+    /// </remarks>
+    protected virtual ValueTask InvokedCoreAsync(InvokedContext context, CancellationToken cancellationToken = default)
         => default;
 
     /// <summary>
@@ -117,7 +186,7 @@ public virtual JsonElement Serialize(JsonSerializerOptions? jsonSerializerOption
         => this.GetService(typeof(TService), serviceKey) is TService service ? service : default;
 
     /// <summary>
-    /// Contains the context information provided to <see cref="InvokingAsync(InvokingContext, CancellationToken)"/>.
+    /// Contains the context information provided to <see cref="InvokingCoreAsync(InvokingContext, CancellationToken)"/>.
     /// </summary>
     /// <remarks>
     /// This class provides context about the invocation before the underlying AI model is invoked, including the messages
@@ -146,7 +215,7 @@ public InvokingContext(IEnumerable<ChatMessage> requestMessages)
     }
 
     /// <summary>
-    /// Contains the context information provided to <see cref="InvokedAsync(InvokedContext, CancellationToken)"/>.
+    /// Contains the context information provided to <see cref="InvokedCoreAsync(InvokedContext, CancellationToken)"/>.
     /// </summary>
     /// <remarks>
     /// This class provides context about a completed agent invocation, including both the
@@ -159,12 +228,10 @@ public sealed class InvokedContext
         /// Initializes a new instance of the <see cref="InvokedContext"/> class with the specified request messages.
         /// </summary>
         /// <param name="requestMessages">The caller provided messages that were used by the agent for this invocation.</param>
-        /// <param name="aiContextProviderMessages">The messages provided by the <see cref="AIContextProvider"/> for this invocation, if any.</param>
         /// <exception cref="ArgumentNullException"><paramref name="requestMessages"/> is <see langword="null"/>.</exception>
-        public InvokedContext(IEnumerable<ChatMessage> requestMessages, IEnumerable<ChatMessage>? aiContextProviderMessages)
+        public InvokedContext(IEnumerable<ChatMessage> requestMessages)
         {
             this.RequestMessages = requestMessages ?? throw new ArgumentNullException(nameof(requestMessages));
-            this.AIContextProviderMessages = aiContextProviderMessages;
         }
 
         /// <summary>
@@ -176,15 +243,6 @@ public InvokedContext(IEnumerable<ChatMessage> requestMessages, IEnumerable<Chat
         /// </value>
         public IEnumerable<ChatMessage> RequestMessages { get; set { field = Throw.IfNull(value); } }
 
-        /// <summary>
-        /// Gets the messages provided by the <see cref="AIContextProvider"/> for this invocation, if any.
-        /// </summary>
-        /// <value>
-        /// A collection of <see cref="ChatMessage"/> instances that were provided by the <see cref="AIContextProvider"/>,
-        /// and were used by the agent as part of the invocation.
-        /// </value>
-        public IEnumerable<ChatMessage>? AIContextProviderMessages { get; set; }
-
         /// <summary>
         /// Gets the collection of response messages generated during this invocation if the invocation succeeded.
         /// </summary>

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

@@ -0,0 +1,106 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using Microsoft.Extensions.AI;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// An enumeration representing the source of an agent request message.
+/// </summary>
+/// <remarks>
+/// Input messages for a specific agent run can originate from various sources.
+/// This enumeration helps to identify whether a message came from outside the agent pipeline,
+/// whether it was produced by middleware, or came from chat history.
+/// </remarks>
+public sealed class AgentRequestMessageSource : IEquatable<AgentRequestMessageSource>
+{
+    /// <summary>
+    /// Provides the key used in <see cref="ChatMessage.AdditionalProperties"/> to store the source of the agent request message.
+    /// </summary>
+    public static readonly string AdditionalPropertiesKey = "Agent.RequestMessageSource";
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AgentRequestMessageSource"/> class.
+    /// </summary>
+    /// <param name="value">The string value representing the source of the agent request message.</param>
+    public AgentRequestMessageSource(string value) => this.Value = Throw.IfNullOrWhitespace(value);
+
+    /// <summary>
+    /// Get the string value representing the source of the agent request message.
+    /// </summary>
+    public string Value { get; }
+
+    /// <summary>
+    /// The message came from outside the agent pipeline (e.g., user input).
+    /// </summary>
+    public static AgentRequestMessageSource External { get; } = new AgentRequestMessageSource(nameof(External));
+
+    /// <summary>
+    /// The message was produced by middleware.
+    /// </summary>
+    public static AgentRequestMessageSource AIContextProvider { get; } = new AgentRequestMessageSource(nameof(AIContextProvider));
+
+    /// <summary>
+    /// The message came from chat history.
+    /// </summary>
+    public static AgentRequestMessageSource ChatHistory { get; } = new AgentRequestMessageSource(nameof(ChatHistory));
+
+    /// <summary>
+    /// Determines whether this instance and another specified <see cref="AgentRequestMessageSource"/> object have the same value.
+    /// </summary>
+    /// <param name="other">The <see cref="AgentRequestMessageSource"/> to compare to this instance.</param>
+    /// <returns><see langword="true"/> if the value of the <paramref name="other"/> parameter is the same as the value of this instance; otherwise, <see langword="false"/>.</returns>
+    public bool Equals(AgentRequestMessageSource? other)
+    {
+        if (other is null)
+        {
+            return false;
+        }
+
+        if (ReferenceEquals(this, other))
+        {
+            return true;
+        }
+
+        return string.Equals(this.Value, other.Value, StringComparison.Ordinal);
+    }
+
+    /// <summary>
+    /// Determines whether this instance and a specified object have the same value.
+    /// </summary>
+    /// <param name="obj">The object to compare to this instance.</param>
+    /// <returns><see langword="true"/> if <paramref name="obj"/> is a <see cref="AgentRequestMessageSource"/> and its value is the same as this instance; otherwise, <see langword="false"/>.</returns>
+    public override bool Equals(object? obj) => this.Equals(obj as AgentRequestMessageSource);
+
+    /// <summary>
+    /// Returns the hash code for this instance.
+    /// </summary>
+    /// <returns>A 32-bit signed integer hash code.</returns>
+    public override int GetHashCode() => this.Value?.GetHashCode() ?? 0;
+
+    /// <summary>
+    /// Determines whether two specified <see cref="AgentRequestMessageSource"/> objects have the same value.
+    /// </summary>
+    /// <param name="left">The first <see cref="AgentRequestMessageSource"/> to compare.</param>
+    /// <param name="right">The second <see cref="AgentRequestMessageSource"/> to compare.</param>
+    /// <returns><see langword="true"/> if the value of <paramref name="left"/> is the same as the value of <paramref name="right"/>; otherwise, <see langword="false"/>.</returns>
+    public static bool operator ==(AgentRequestMessageSource? left, AgentRequestMessageSource? right)
+    {
+        if (left is null)
+        {
+            return right is null;
+        }
+
+        return left.Equals(right);
+    }
+
+    /// <summary>
+    /// Determines whether two specified <see cref="AgentRequestMessageSource"/> objects have different values.
+    /// </summary>
+    /// <param name="left">The first <see cref="AgentRequestMessageSource"/> to compare.</param>
+    /// <param name="right">The second <see cref="AgentRequestMessageSource"/> to compare.</param>
+    /// <returns><see langword="true"/> if the value of <paramref name="left"/> is different from the value of <paramref name="right"/>; otherwise, <see langword="false"/>.</returns>
+    public static bool operator !=(AgentRequestMessageSource? left, AgentRequestMessageSource? right) => !(left == right);
+}