.Net: Change Agents.Abstractions to depend on SemanticKernel.Abstract…

…ions instead of SemanticKernel.Core (#10574)

### Motivation and Context

Closes #10571 

### Description

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

### Contribution Checklist

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

- [ ] The code builds clean without any errors or warnings
- [ ] 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
- [ ] All unit tests pass, and I have added new tests where possible
- [ ] I didn't break anyone 😄

dotnet/samples/Concepts/Agents/ChatCompletion_Templating.cs

@@ -50,7 +50,9 @@ await InvokeChatCompletionAgentWithTemplateAsync(
             """
             Write a one verse poem on the requested topic in the style of {{$style}}.
             Always state the requested style of the poem.
-            """);
+            """,
+            PromptTemplateConfig.SemanticKernelTemplateFormat,
+            new KernelPromptTemplateFactory());
     }
 
     [Fact]
@@ -79,8 +81,8 @@ Always state the requested style of the poem.
 
     private async Task InvokeChatCompletionAgentWithTemplateAsync(
         string instructionTemplate,
-        string? templateFormat = null,
-        IPromptTemplateFactory? templateFactory = null)
+        string templateFormat,
+        IPromptTemplateFactory templateFactory)
     {
         // Define the agent
         PromptTemplateConfig templateConfig =

dotnet/samples/Concepts/Agents/OpenAIAssistant_Templating.cs

@@ -55,7 +55,9 @@ await InvokeAssistantAgentWithTemplateAsync(
             """
             Write a one verse poem on the requested topic in the styles of {{$style}}.
             Always state the requested style of the poem.
-            """);
+            """,
+            PromptTemplateConfig.SemanticKernelTemplateFormat,
+            new KernelPromptTemplateFactory());
     }
 
     [Fact]

dotnet/samples/GettingStartedWithAgents/Step01_Agent.cs

@@ -59,10 +59,11 @@ public async Task UseTemplateForChatCompletionAgentAsync()
         // Define the agent
         string generateStoryYaml = EmbeddedResource.Read("GenerateStory.yaml");
         PromptTemplateConfig templateConfig = KernelFunctionYaml.ToPromptTemplateConfig(generateStoryYaml);
+        KernelPromptTemplateFactory templateFactory = new();
 
         // Instructions, Name and Description properties defined via the config.
         ChatCompletionAgent agent =
-            new(templateConfig)
+            new(templateConfig, templateFactory)
             {
                 Kernel = this.CreateKernelWithChatCompletion(),
                 Arguments =

dotnet/samples/GettingStartedWithAgents/Step02_Plugins.cs

@@ -52,11 +52,12 @@ public async Task UseChatCompletionWithTemplateExecutionSettingsAsync()
         // Read the template resource
         string autoInvokeYaml = EmbeddedResource.Read("AutoInvokeTools.yaml");
         PromptTemplateConfig templateConfig = KernelFunctionYaml.ToPromptTemplateConfig(autoInvokeYaml);
+        KernelPromptTemplateFactory templateFactory = new();
 
         // Define the agent:
         // Execution-settings with auto-invocation of plugins defined via the config.
         ChatCompletionAgent agent =
-            new(templateConfig)
+            new(templateConfig, templateFactory)
             {
                 Kernel = this.CreateKernelWithChatCompletion()
             };

dotnet/src/Agents/Abstractions/Agents.Abstractions.csproj

@@ -30,7 +30,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\SemanticKernel.Core\SemanticKernel.Core.csproj" />
+    <ProjectReference Include="..\..\SemanticKernel.Abstractions\SemanticKernel.Abstractions.csproj" />
   </ItemGroup>
 
   <ItemGroup>

dotnet/src/Agents/Abstractions/KernelAgent.cs

@@ -23,9 +23,6 @@ public abstract class KernelAgent : Agent
     /// <summary>
     /// Gets the instructions for the agent (optional).
     /// </summary>
-    /// <remarks>
-    /// Instructions can be formatted in "semantic-kernel" template format (<see cref="KernelPromptTemplateFactory"/>).
-    /// </remarks>
     public string? Instructions { get; init; }
 
     /// <summary>
@@ -39,7 +36,7 @@ public abstract class KernelAgent : Agent
     /// <summary>
     /// Gets or sets a prompt template based on the agent instructions.
     /// </summary>
-    public IPromptTemplate? Template { get; protected set; }
+    protected IPromptTemplate? Template { get; set; }
 
     /// <inheritdoc/>
     protected override ILoggerFactory ActiveLoggerFactory => this.LoggerFactory ?? this.Kernel.LoggerFactory;
@@ -53,19 +50,14 @@ public abstract class KernelAgent : Agent
     /// <returns>The formatted system instructions for the agent.</returns>
     protected async Task<string?> FormatInstructionsAsync(Kernel kernel, KernelArguments? arguments, CancellationToken cancellationToken)
     {
-        // If <see cref="Template"/> is not set, default instructions may be treated as "semantic-kernel" template.
-        if (this.Template == null)
+        // Use the provided template as the instructions
+        if (this.Template is not null)
         {
-            if (string.IsNullOrWhiteSpace(this.Instructions))
-            {
-                return null;
-            }
-
-            KernelPromptTemplateFactory templateFactory = new(this.LoggerFactory);
-            this.Template = templateFactory.Create(new PromptTemplateConfig(this.Instructions!));
+            return await this.Template.RenderAsync(kernel, arguments, cancellationToken).ConfigureAwait(false);
         }
 
-        return await this.Template.RenderAsync(kernel, arguments, cancellationToken).ConfigureAwait(false);
+        // Use the instructions as-is
+        return this.Instructions;
     }
 
     /// <summary>

dotnet/src/Agents/AzureAI/AzureAIAgent.cs

@@ -54,23 +54,25 @@ public static class Tools
     /// </summary>
     /// <param name="model">The agent model definition.</param>
     /// <param name="client">An <see cref="AgentsClient"/> instance.</param>
+    /// <param name="templateConfig">The prompt template configuration.</param>
     /// <param name="templateFactory">An optional template factory.</param>
     public AzureAIAgent(
         Azure.AI.Projects.Agent model,
         AgentsClient client,
+        PromptTemplateConfig? templateConfig = null,
         IPromptTemplateFactory? templateFactory = null)
     {
         this.Client = client;
         this.Definition = model;
         this.Description = this.Definition.Description;
         this.Id = this.Definition.Id;
         this.Name = this.Definition.Name;
-        this.Instructions = this.Definition.Instructions;
+        this.Instructions = templateConfig?.Template ?? this.Definition.Instructions;
 
-        if (templateFactory != null)
+        if (templateConfig is not null)
         {
-            PromptTemplateConfig templateConfig = new(this.Instructions);
-            this.Template = templateFactory.Create(templateConfig);
+            this.Template = templateFactory?.Create(templateConfig)
+                ?? throw new KernelException($"Invalid prompt template factory {templateFactory} for format {templateConfig.TemplateFormat}");
         }
     }
 

dotnet/src/Agents/Core/Agents.Core.csproj

@@ -27,6 +27,7 @@
 
   <ItemGroup>
     <ProjectReference Include="..\Abstractions\Agents.Abstractions.csproj" />
+    <ProjectReference Include="..\..\SemanticKernel.Core\SemanticKernel.Core.csproj" />
   </ItemGroup>
 
   <ItemGroup>

dotnet/src/Agents/Core/ChatCompletionAgent.cs

@@ -32,19 +32,16 @@ public ChatCompletionAgent() { }
     /// a <see cref="PromptTemplateConfig"/>.
     /// </summary>
     /// <param name="templateConfig">The prompt template configuration.</param>
-    /// <param name="templateFactory">An optional factory to produce the <see cref="IPromptTemplate"/> for the agent.</param>
-    /// <remarks>
-    /// When a template factory argument isn't provided, the default <see cref="KernelPromptTemplateFactory"/> is used.
-    /// </remarks>
+    /// <param name="templateFactory">The prompt template factory used to produce the <see cref="IPromptTemplate"/> for the agent.</param>
     public ChatCompletionAgent(
         PromptTemplateConfig templateConfig,
-        IPromptTemplateFactory? templateFactory = null)
+        IPromptTemplateFactory templateFactory)
     {
         this.Name = templateConfig.Name;
         this.Description = templateConfig.Description;
         this.Instructions = templateConfig.Template;
         this.Arguments = new(templateConfig.ExecutionSettings.Values);
-        this.Template = templateFactory?.Create(templateConfig);
+        this.Template = templateFactory.Create(templateConfig);
     }
 
     /// <summary>
@@ -99,12 +96,10 @@ protected override Task<AgentChannel> RestoreChannelAsync(string channelState, C
 
     internal static (IChatCompletionService service, PromptExecutionSettings? executionSettings) GetChatCompletionService(Kernel kernel, KernelArguments? arguments)
     {
-        // Need to provide a KernelFunction to the service selector as a container for the execution-settings.
-        KernelFunction nullPrompt = KernelFunctionFactory.CreateFromPrompt("placeholder", arguments?.ExecutionSettings?.Values);
         (IChatCompletionService chatCompletionService, PromptExecutionSettings? executionSettings) =
             kernel.ServiceSelector.SelectAIService<IChatCompletionService>(
                 kernel,
-                nullPrompt,
+                arguments?.ExecutionSettings,
                 arguments ?? []);
 
         return (chatCompletionService, executionSettings);

dotnet/src/Agents/OpenAI/OpenAIAssistantAgent.cs

@@ -53,9 +53,10 @@ public OpenAIAssistantAgent(
         this.Name = this.Definition.Name;
         this.Instructions = templateConfig?.Template ?? this.Definition.Instructions;
 
-        if (templateConfig != null)
+        if (templateConfig is not null)
         {
-            this.Template = templateFactory?.Create(templateConfig);
+            this.Template = templateFactory?.Create(templateConfig)
+                ?? throw new KernelException($"Invalid prompt template factory {templateFactory} for format {templateConfig.TemplateFormat}");
         }
 
         if (plugins != null)
@@ -101,7 +102,7 @@ public OpenAIAssistantAgent(
     /// <param name="kernel">The <see cref="Kernel"/> containing services, plugins, and other state for use throughout the operation.</param>
     /// <param name="defaultArguments">Required arguments that provide default template parameters, including any <see cref="PromptExecutionSettings"/>.</param>
     /// <param name="templateConfig">The prompt template configuration.</param>
-    /// <param name="templateFactory">An optional factory to produce the <see cref="IPromptTemplate"/> for the agent.</param>
+    /// <param name="templateFactory">An prompt template factory to produce the <see cref="IPromptTemplate"/> for the agent.</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="OpenAIAssistantAgent"/> instance.</returns>
     [Obsolete("Use the OpenAI.Assistants.AssistantClient to create an assistant (CreateAssistantFromTemplateAsync).")]
@@ -111,7 +112,7 @@ public static async Task<OpenAIAssistantAgent> CreateFromTemplateAsync(
         Kernel kernel,
         KernelArguments defaultArguments,
         PromptTemplateConfig templateConfig,
-        IPromptTemplateFactory? templateFactory = null,
+        IPromptTemplateFactory templateFactory,
         CancellationToken cancellationToken = default)
     {
         // Validate input
@@ -120,9 +121,10 @@ public static async Task<OpenAIAssistantAgent> CreateFromTemplateAsync(
         Verify.NotNull(clientProvider, nameof(clientProvider));
         Verify.NotNull(capabilities, nameof(capabilities));
         Verify.NotNull(templateConfig, nameof(templateConfig));
+        Verify.NotNull(templateFactory, nameof(templateFactory));
 
         // Ensure template is valid (avoid failure after posting assistant creation)
-        IPromptTemplate? template = templateFactory?.Create(templateConfig);
+        IPromptTemplate template = templateFactory.Create(templateConfig);
 
         // Create the client
         AssistantClient client = clientProvider.Client.GetAssistantClient();

dotnet/src/Agents/UnitTests/Agents.UnitTests.csproj

@@ -35,6 +35,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <ProjectReference Include="..\..\Extensions\PromptTemplates.Handlebars\PromptTemplates.Handlebars.csproj" />
     <ProjectReference Include="..\Abstractions\Agents.Abstractions.csproj" />
     <ProjectReference Include="..\..\Connectors\Connectors.AzureOpenAI\Connectors.AzureOpenAI.csproj" />
     <ProjectReference Include="..\Core\Agents.Core.csproj" />

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

@@ -46,7 +46,7 @@ public void VerifyChatCompletionAgentDefinition()
     [Fact]
     public void VerifyChatCompletionAgentTemplate()
     {
-        PromptTemplateConfig config =
+        PromptTemplateConfig promptConfig =
             new()
             {
                 Name = "TestName",
@@ -73,16 +73,38 @@ public void VerifyChatCompletionAgentTemplate()
                     },
                 }
             };
+        KernelPromptTemplateFactory templateFactory = new();
 
         // Arrange
-        ChatCompletionAgent agent = new(config);
+        ChatCompletionAgent agent = new(promptConfig, templateFactory);
 
         // Assert
         Assert.NotNull(agent.Id);
-        Assert.Equal(config.Template, agent.Instructions);
-        Assert.Equal(config.Description, agent.Description);
-        Assert.Equal(config.Name, agent.Name);
-        Assert.Equal(config.ExecutionSettings, agent.Arguments.ExecutionSettings);
+        Assert.Equal(promptConfig.Template, agent.Instructions);
+        Assert.Equal(promptConfig.Description, agent.Description);
+        Assert.Equal(promptConfig.Name, agent.Name);
+        Assert.Equal(promptConfig.ExecutionSettings, agent.Arguments.ExecutionSettings);
+    }
+
+    /// <summary>
+    /// Verify throws <see cref="KernelException"/> when invalid <see cref="IPromptTemplateFactory"/> is provided.
+    /// </summary>
+    [Fact]
+    public void VerifyThrowsForInvalidTemplateFactory()
+    {
+        // Arrange
+        PromptTemplateConfig promptConfig =
+            new()
+            {
+                Name = "TestName",
+                Description = "TestDescription",
+                Template = "TestInstructions",
+                TemplateFormat = "handlebars",
+            };
+        KernelPromptTemplateFactory templateFactory = new();
+
+        // Act and Assert
+        Assert.Throws<KernelException>(() => new ChatCompletionAgent(promptConfig, templateFactory));
     }
 
     /// <summary>

dotnet/src/Agents/UnitTests/OpenAI/OpenAIAssistantAgentTests.cs

@@ -10,6 +10,7 @@
 using Microsoft.SemanticKernel.Agents;
 using Microsoft.SemanticKernel.Agents.OpenAI;
 using Microsoft.SemanticKernel.ChatCompletion;
+using Microsoft.SemanticKernel.PromptTemplates.Handlebars;
 using OpenAI.Assistants;
 using Xunit;
 
@@ -76,11 +77,9 @@ public async Task VerifyOpenAIAssistantAgentCreationDefaultTemplateAsync()
 
         OpenAIAssistantCapabilities capabilities = new("testmodel");
 
-        // Act and Assert
-        await this.VerifyAgentTemplateAsync(capabilities, templateConfig);
-
         // Act and Assert
         await this.VerifyAgentTemplateAsync(capabilities, templateConfig, new KernelPromptTemplateFactory());
+        await Assert.ThrowsAsync<KernelException>(async () => await this.VerifyAgentTemplateAsync(capabilities, templateConfig, new HandlebarsPromptTemplateFactory()));
     }
 
     /// <summary>
@@ -734,7 +733,7 @@ await OpenAIAssistantAgent.CreateAsync(
     private async Task VerifyAgentTemplateAsync(
         OpenAIAssistantCapabilities capabilities,
         PromptTemplateConfig templateConfig,
-        IPromptTemplateFactory? templateFactory = null)
+        IPromptTemplateFactory templateFactory)
     {
         this.SetupResponse(HttpStatusCode.OK, capabilities, templateConfig);
 

dotnet/src/SemanticKernel.Abstractions/Functions/KernelFunctionNoop.cs

@@ -0,0 +1,46 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.SemanticKernel;
+
+/// <summary>
+/// Represents a kernel function that performs no operation.
+/// </summary>
+[RequiresUnreferencedCode("Uses reflection to handle various aspects of the function creation and invocation, making it incompatible with AOT scenarios.")]
+[RequiresDynamicCode("Uses reflection to handle various aspects of the function creation and invocation, making it incompatible with AOT scenarios.")]
+internal sealed class KernelFunctionNoop : KernelFunction
+{
+    /// <summary>
+    /// Creates a new instance of the <see cref="KernelFunctionNoop"/> class.
+    /// </summary>
+    /// <param name="executionSettings">Option: Prompt execution settings.</param>
+    internal KernelFunctionNoop(IReadOnlyDictionary<string, PromptExecutionSettings>? executionSettings) :
+        base($"Function_{Guid.NewGuid():N}", string.Empty, [], null, executionSettings?.ToDictionary(static kv => kv.Key, static kv => kv.Value))
+    {
+    }
+
+    /// <inheritdoc/>
+    public override KernelFunction Clone(string pluginName)
+    {
+        Dictionary<string, PromptExecutionSettings>? executionSettings = this.ExecutionSettings?.ToDictionary(kv => kv.Key, kv => kv.Value);
+        return new KernelFunctionNoop(executionSettings);
+    }
+
+    /// <inheritdoc/>
+    protected override ValueTask<FunctionResult> InvokeCoreAsync(Kernel kernel, KernelArguments arguments, CancellationToken cancellationToken)
+    {
+        return new(new FunctionResult(this));
+    }
+
+    /// <inheritdoc/>
+    protected override IAsyncEnumerable<TResult> InvokeStreamingCoreAsync<TResult>(Kernel kernel, KernelArguments arguments, CancellationToken cancellationToken)
+    {
+        return AsyncEnumerable.Empty<TResult>();
+    }
+}