.Net Agents - Direct logger association with Agent (#6933)

### Motivation and Context
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  1. Why is this change required?
  2. What problem does it solve?
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Enable direct assignment of `LoggerFactory` for agent managed `Logger`
in support of single-agent (no chat) scenario.

### Description
<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->
- Add `Agent.LoggerFactory` and `Agent.Logger`
- Remove `logger` parameter from `Agent.CreateChannelAsync`
- Remove `logger` parameter from `IChatHistoryHandler.InvokeAsync`
- Update all down-stream definitions


### Contribution Checklist
<!-- Before submitting this PR, please make sure: -->

- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

dotnet/samples/GettingStartedWithAgents/Step7_Logging.cs

@@ -46,6 +46,7 @@ public async Task UseLoggerFactoryWithAgentGroupChatAsync()
                 Instructions = ReviewerInstructions,
                 Name = ReviewerName,
                 Kernel = this.CreateKernelWithChatCompletion(),
+                LoggerFactory = this.LoggerFactory,
             };
 
         ChatCompletionAgent agentWriter =
@@ -54,6 +55,7 @@ public async Task UseLoggerFactoryWithAgentGroupChatAsync()
                 Instructions = CopyWriterInstructions,
                 Name = CopyWriterName,
                 Kernel = this.CreateKernelWithChatCompletion(),
+                LoggerFactory = this.LoggerFactory,
             };
 
         // Create a chat for agent interaction.

dotnet/src/Agents/Abstractions/Agent.cs

@@ -4,6 +4,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
 
 namespace Microsoft.SemanticKernel.Agents;
 
@@ -36,6 +37,16 @@ public abstract class Agent
     /// </summary>
     public string? Name { get; init; }
 
+    /// <summary>
+    /// A <see cref="ILoggerFactory"/> for this <see cref="Agent"/>.
+    /// </summary>
+    public ILoggerFactory LoggerFactory { get; init; } = NullLoggerFactory.Instance;
+
+    /// <summary>
+    /// The <see cref="ILogger"/> associated with this  <see cref="Agent"/>.
+    /// </summary>
+    protected ILogger Logger => this._logger ??= this.LoggerFactory.CreateLogger(this.GetType());
+
     /// <summary>
     /// Set of keys to establish channel affinity.  Minimum expected key-set:
     /// <example>
@@ -53,12 +64,13 @@ public abstract class Agent
     /// <summary>
     /// Produce the an <see cref="AgentChannel"/> appropriate for the agent type.
     /// </summary>
-    /// <param name="logger">An agent specific logger.</param>
     /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
     /// <returns>An <see cref="AgentChannel"/> appropriate for the agent type.</returns>
     /// <remarks>
     /// Every agent conversation, or <see cref="AgentChat"/>, will establish one or more <see cref="AgentChannel"/>
     /// objects according to the specific <see cref="Agent"/> type.
     /// </remarks>
-    protected internal abstract Task<AgentChannel> CreateChannelAsync(ILogger logger, CancellationToken cancellationToken);
+    protected internal abstract Task<AgentChannel> CreateChannelAsync(CancellationToken cancellationToken);
+
+    private ILogger? _logger;
 }

dotnet/src/Agents/Abstractions/AgentChat.cs

@@ -256,10 +256,7 @@ async Task<AgentChannel> GetOrCreateChannelAsync()
             {
                 this.Logger.LogDebug("[{MethodName}] Creating channel for {AgentType}: {AgentId}", nameof(InvokeAgentAsync), agent.GetType(), agent.Id);
 
-                // Creating an agent-typed logger for CreateChannelAsync
-                channel = await agent.CreateChannelAsync(this.LoggerFactory.CreateLogger(agent.GetType()), cancellationToken).ConfigureAwait(false);
-                // Creating an channel-typed logger for the channel
-                channel.Logger = this.LoggerFactory.CreateLogger(channel.GetType());
+                channel = await agent.CreateChannelAsync(cancellationToken).ConfigureAwait(false);
 
                 this._agentChannels.Add(channelKey, channel);
 

dotnet/src/Agents/Abstractions/AggregatorAgent.cs

@@ -44,14 +44,14 @@ protected internal override IEnumerable<string> GetChannelKeys()
     }
 
     /// <inheritdoc/>
-    protected internal override Task<AgentChannel> CreateChannelAsync(ILogger logger, CancellationToken cancellationToken)
+    protected internal override Task<AgentChannel> CreateChannelAsync(CancellationToken cancellationToken)
     {
-        logger.LogDebug("[{MethodName}] Creating channel {ChannelType}", nameof(CreateChannelAsync), nameof(AggregatorChannel));
+        this.Logger.LogDebug("[{MethodName}] Creating channel {ChannelType}", nameof(CreateChannelAsync), nameof(AggregatorChannel));
 
         AgentChat chat = chatProvider.Invoke();
         AggregatorChannel channel = new(chat);
 
-        logger.LogInformation("[{MethodName}] Created channel {ChannelType} ({ChannelMode}) with: {AgentChatType}", nameof(CreateChannelAsync), nameof(AggregatorChannel), this.Mode, chat.GetType());
+        this.Logger.LogInformation("[{MethodName}] Created channel {ChannelType} ({ChannelMode}) with: {AgentChatType}", nameof(CreateChannelAsync), nameof(AggregatorChannel), this.Mode, chat.GetType());
 
         return Task.FromResult<AgentChannel>(channel);
     }

dotnet/src/Agents/Abstractions/ChatHistoryChannel.cs

@@ -25,7 +25,7 @@ public class ChatHistoryChannel : AgentChannel
             throw new KernelException($"Invalid channel binding for agent: {agent.Id} ({agent.GetType().FullName})");
         }
 
-        await foreach (var message in historyHandler.InvokeAsync(this._history, this.Logger, cancellationToken).ConfigureAwait(false))
+        await foreach (var message in historyHandler.InvokeAsync(this._history, cancellationToken).ConfigureAwait(false))
         {
             this._history.Add(message);
 

dotnet/src/Agents/Abstractions/ChatHistoryKernelAgent.cs

@@ -18,14 +18,19 @@ protected internal sealed override IEnumerable<string> GetChannelKeys()
     }
 
     /// <inheritdoc/>
-    protected internal sealed override Task<AgentChannel> CreateChannelAsync(ILogger logger, CancellationToken cancellationToken)
+    protected internal sealed override Task<AgentChannel> CreateChannelAsync(CancellationToken cancellationToken)
     {
-        return Task.FromResult<AgentChannel>(new ChatHistoryChannel());
+        ChatHistoryChannel channel =
+            new()
+            {
+                Logger = this.LoggerFactory.CreateLogger<ChatHistoryChannel>()
+            };
+
+        return Task.FromResult<AgentChannel>(channel);
     }
 
     /// <inheritdoc/>
     public abstract IAsyncEnumerable<ChatMessageContent> InvokeAsync(
         IReadOnlyList<ChatMessageContent> history,
-        ILogger logger,
         CancellationToken cancellationToken = default);
 }

dotnet/src/Agents/Abstractions/IChatHistoryHandler.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 using System.Collections.Generic;
 using System.Threading;
-using Microsoft.Extensions.Logging;
 
 namespace Microsoft.SemanticKernel.Agents;
 
@@ -14,11 +13,9 @@ public interface IChatHistoryHandler
     /// Entry point for calling into an agent from a a <see cref="ChatHistoryChannel"/>.
     /// </summary>
     /// <param name="history">The chat history at the point the channel is created.</param>
-    /// <param name="logger">The logger associated with the <see cref="ChatHistoryChannel"/></param>
     /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
     /// <returns>Asynchronous enumeration of messages.</returns>
     IAsyncEnumerable<ChatMessageContent> InvokeAsync(
         IReadOnlyList<ChatMessageContent> history,
-        ILogger logger,
         CancellationToken cancellationToken = default);
 }

dotnet/src/Agents/Core/ChatCompletionAgent.cs

@@ -24,7 +24,6 @@ public sealed class ChatCompletionAgent : ChatHistoryKernelAgent
     /// <inheritdoc/>
     public override async IAsyncEnumerable<ChatMessageContent> InvokeAsync(
         IReadOnlyList<ChatMessageContent> history,
-        ILogger logger,
         [EnumeratorCancellation] CancellationToken cancellationToken = default)
     {
         var chatCompletionService = this.Kernel.GetRequiredService<IChatCompletionService>();
@@ -38,7 +37,7 @@ public sealed class ChatCompletionAgent : ChatHistoryKernelAgent
 
         int messageCount = chat.Count;
 
-        logger.LogDebug("[{MethodName}] Invoking {ServiceType}.", nameof(InvokeAsync), chatCompletionService.GetType());
+        this.Logger.LogDebug("[{MethodName}] Invoking {ServiceType}.", nameof(InvokeAsync), chatCompletionService.GetType());
 
         IReadOnlyList<ChatMessageContent> messages =
             await chatCompletionService.GetChatMessageContentsAsync(
@@ -47,9 +46,9 @@ public sealed class ChatCompletionAgent : ChatHistoryKernelAgent
                 this.Kernel,
                 cancellationToken).ConfigureAwait(false);
 
-        if (logger.IsEnabled(LogLevel.Information)) // Avoid boxing if not enabled
+        if (this.Logger.IsEnabled(LogLevel.Information)) // Avoid boxing if not enabled
         {
-            logger.LogInformation("[{MethodName}] Invoked {ServiceType} with message count: {MessageCount}.", nameof(InvokeAsync), chatCompletionService.GetType(), messages.Count);
+            this.Logger.LogInformation("[{MethodName}] Invoked {ServiceType} with message count: {MessageCount}.", nameof(InvokeAsync), chatCompletionService.GetType(), messages.Count);
         }
 
         // Capture mutated messages related function calling / tools

dotnet/src/Agents/OpenAI/OpenAIAssistantAgent.cs

@@ -204,13 +204,13 @@ protected override IEnumerable<string> GetChannelKeys()
     }
 
     /// <inheritdoc/>
-    protected override async Task<AgentChannel> CreateChannelAsync(ILogger logger, CancellationToken cancellationToken)
+    protected override async Task<AgentChannel> CreateChannelAsync(CancellationToken cancellationToken)
     {
-        logger.LogDebug("[{MethodName}] Creating assistant thread", nameof(CreateChannelAsync));
+        this.Logger.LogDebug("[{MethodName}] Creating assistant thread", nameof(CreateChannelAsync));
 
         AssistantThread thread = await this._client.CreateThreadAsync(cancellationToken).ConfigureAwait(false);
 
-        logger.LogInformation("[{MethodName}] Created assistant thread: {ThreadId}", nameof(CreateChannelAsync), thread.Id);
+        this.Logger.LogInformation("[{MethodName}] Created assistant thread: {ThreadId}", nameof(CreateChannelAsync), thread.Id);
 
         return new OpenAIAssistantChannel(this._client, thread.Id, this._config.Polling);
     }

dotnet/src/Agents/UnitTests/AgentChannelTests.cs

@@ -5,7 +5,6 @@
 using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.Extensions.Logging;
 using Microsoft.SemanticKernel;
 using Microsoft.SemanticKernel.Agents;
 using Xunit;
@@ -68,7 +67,7 @@ private sealed class NextAgent : TestAgent;
 
     private class TestAgent : KernelAgent
     {
-        protected internal override Task<AgentChannel> CreateChannelAsync(ILogger logger, CancellationToken cancellationToken)
+        protected internal override Task<AgentChannel> CreateChannelAsync(CancellationToken cancellationToken)
         {
             throw new NotImplementedException();
         }

dotnet/src/Agents/UnitTests/AgentChatTests.cs

@@ -4,7 +4,6 @@
 using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.Extensions.Logging;
 using Microsoft.SemanticKernel;
 using Microsoft.SemanticKernel.Agents;
 using Microsoft.SemanticKernel.ChatCompletion;
@@ -137,7 +136,6 @@ private sealed class TestAgent : ChatHistoryKernelAgent
 
         public override async IAsyncEnumerable<ChatMessageContent> InvokeAsync(
             IReadOnlyList<ChatMessageContent> history,
-            ILogger logger,
             [EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
             await Task.Delay(0, cancellationToken);

dotnet/src/Agents/UnitTests/AggregatorAgentTests.cs

@@ -3,7 +3,6 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.Extensions.Logging;
 using Microsoft.SemanticKernel;
 using Microsoft.SemanticKernel.Agents;
 using Microsoft.SemanticKernel.ChatCompletion;
@@ -88,7 +87,7 @@ private static Mock<ChatHistoryKernelAgent> CreateMockAgent()
         Mock<ChatHistoryKernelAgent> agent = new();
 
         ChatMessageContent[] messages = [new ChatMessageContent(AuthorRole.Assistant, "test agent")];
-        agent.Setup(a => a.InvokeAsync(It.IsAny<IReadOnlyList<ChatMessageContent>>(), It.IsAny<ILogger>(), It.IsAny<CancellationToken>())).Returns(() => messages.ToAsyncEnumerable());
+        agent.Setup(a => a.InvokeAsync(It.IsAny<IReadOnlyList<ChatMessageContent>>(), It.IsAny<CancellationToken>())).Returns(() => messages.ToAsyncEnumerable());
 
         return agent;
     }

dotnet/src/Agents/UnitTests/ChatHistoryChannelTests.cs

@@ -4,7 +4,6 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.Extensions.Logging;
 using Microsoft.SemanticKernel;
 using Microsoft.SemanticKernel.Agents;
 using Xunit;
@@ -30,7 +29,7 @@ public async Task VerifyAgentWithoutIChatHistoryHandlerAsync()
 
     private sealed class TestAgent : KernelAgent
     {
-        protected internal override Task<AgentChannel> CreateChannelAsync(ILogger logger, CancellationToken cancellationToken)
+        protected internal override Task<AgentChannel> CreateChannelAsync(CancellationToken cancellationToken)
         {
             throw new NotImplementedException();
         }

dotnet/src/Agents/UnitTests/Core/AgentGroupChatTests.cs

@@ -4,7 +4,6 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.Extensions.Logging;
 using Microsoft.SemanticKernel;
 using Microsoft.SemanticKernel.Agents;
 using Microsoft.SemanticKernel.Agents.Chat;
@@ -199,7 +198,7 @@ private static Mock<ChatHistoryKernelAgent> CreateMockAgent()
         Mock<ChatHistoryKernelAgent> agent = new();
 
         ChatMessageContent[] messages = [new ChatMessageContent(AuthorRole.Assistant, "test")];
-        agent.Setup(a => a.InvokeAsync(It.IsAny<IReadOnlyList<ChatMessageContent>>(), It.IsAny<ILogger>(), It.IsAny<CancellationToken>())).Returns(() => messages.ToAsyncEnumerable());
+        agent.Setup(a => a.InvokeAsync(It.IsAny<IReadOnlyList<ChatMessageContent>>(), It.IsAny<CancellationToken>())).Returns(() => messages.ToAsyncEnumerable());
 
         return agent;
     }

dotnet/src/Agents/UnitTests/Core/ChatCompletionAgentTests.cs

@@ -3,7 +3,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.SemanticKernel;
 using Microsoft.SemanticKernel.Agents;
 using Microsoft.SemanticKernel.ChatCompletion;
@@ -60,7 +59,7 @@ public async Task VerifyChatCompletionAgentInvocationAsync()
                 ExecutionSettings = new(),
             };
 
-        var result = await agent.InvokeAsync([], NullLogger.Instance).ToArrayAsync();
+        var result = await agent.InvokeAsync([]).ToArrayAsync();
 
         Assert.Single(result);