.NET: skill as class

.gitignore

@@ -230,3 +230,6 @@ local.settings.json
 # Database files
 *.db
 python/dotnet-ref
+
+# Generated filtered solution files (created by eng/scripts/New-FilteredSolution.ps1)
+dotnet/filtered-*.slnx

dotnet/AGENTS.md

@@ -36,7 +36,7 @@ using types like `IChatClient`, `FunctionInvokingChatClient`, `AITool`, `AIFunct
 - **Async**: Use `Async` suffix for methods returning `Task`/`ValueTask`
 - **Private classes**: Should be `sealed` unless subclassed
 - **Config**: Read from environment variables with `UPPER_SNAKE_CASE` naming
-- **Tests**: Add Arrange/Act/Assert comments; use Moq for mocking
+- **Tests**: Add Arrange/Act/Assert comments; use Moq for mocking; test methods returning `Task`/`ValueTask` must use the `Async` suffix.
 
 ## Key Design Principles
 

dotnet/agent-framework-dotnet.slnx

@@ -106,6 +106,9 @@
     <File Path="samples/02-agents/AgentSkills/README.md" />
     <Project Path="samples/02-agents/AgentSkills/Agent_Step01_FileBasedSkills/Agent_Step01_FileBasedSkills.csproj" />
     <Project Path="samples/02-agents/AgentSkills/Agent_Step02_CodeDefinedSkills/Agent_Step02_CodeDefinedSkills.csproj" />
+    <Project Path="samples/02-agents/AgentSkills/Agent_Step03_ClassBasedSkills/Agent_Step03_ClassBasedSkills.csproj" />
+    <Project Path="samples/02-agents/AgentSkills/Agent_Step04_MixedSkills/Agent_Step04_MixedSkills.csproj" />
+    <Project Path="samples/02-agents/AgentSkills/Agent_Step05_SkillsWithDI/Agent_Step05_SkillsWithDI.csproj" />
   </Folder>
   <Folder Name="/Samples/02-agents/AGUI/Step05_StateManagement/">
     <Project Path="samples/02-agents/AGUI/Step05_StateManagement/Client/Client.csproj" />

dotnet/samples/02-agents/AgentSkills/Agent_Step01_FileBasedSkills/README.md

@@ -6,7 +6,7 @@ This sample demonstrates how to use **file-based Agent Skills** with a `ChatClie
 
 - Discovering skills from `SKILL.md` files on disk via `AgentFileSkillsSource`
 - The progressive disclosure pattern: advertise → load → read resources → run scripts
-- Using the `AgentSkillsProvider` constructor with a skill directory path and script executor
+- Using the `AgentSkillsProvider` constructor with a skill directory path and script runner
 - Running file-based scripts (Python) via a subprocess-based executor
 
 ## Skills Included

dotnet/samples/02-agents/AgentSkills/Agent_Step03_ClassBasedSkills/Agent_Step03_ClassBasedSkills.csproj

@@ -0,0 +1,21 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <NoWarn>$(NoWarn);MAAI001</NoWarn>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Azure.AI.OpenAI" />
+    <PackageReference Include="Azure.Identity" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\src\Microsoft.Agents.AI.OpenAI\Microsoft.Agents.AI.OpenAI.csproj" />
+  </ItemGroup>
+
+</Project>

dotnet/samples/02-agents/AgentSkills/Agent_Step03_ClassBasedSkills/Program.cs

@@ -0,0 +1,102 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// This sample demonstrates how to define Agent Skills as C# classes using AgentClassSkill.
+// Class-based skills bundle all components into a single class implementation.
+
+using System.Text.Json;
+using Azure.AI.OpenAI;
+using Azure.Identity;
+using Microsoft.Agents.AI;
+using OpenAI.Responses;
+
+// --- Configuration ---
+string endpoint = Environment.GetEnvironmentVariable("AZURE_OPENAI_ENDPOINT") ?? throw new InvalidOperationException("AZURE_OPENAI_ENDPOINT is not set.");
+string deploymentName = Environment.GetEnvironmentVariable("AZURE_OPENAI_DEPLOYMENT_NAME") ?? "gpt-4o-mini";
+
+// --- Class-Based Skill ---
+// Instantiate the skill class.
+var unitConverter = new UnitConverterSkill();
+
+// --- Skills Provider ---
+var skillsProvider = new AgentSkillsProvider(unitConverter);
+
+// --- Agent Setup ---
+AIAgent agent = new AzureOpenAIClient(new Uri(endpoint), new DefaultAzureCredential())
+    .GetResponsesClient()
+    .AsAIAgent(new ChatClientAgentOptions
+    {
+        Name = "UnitConverterAgent",
+        ChatOptions = new()
+        {
+            Instructions = "You are a helpful assistant that can convert units.",
+        },
+        AIContextProviders = [skillsProvider],
+    },
+    model: deploymentName);
+
+// --- Example: Unit conversion ---
+Console.WriteLine("Converting units with class-based skills");
+Console.WriteLine(new string('-', 60));
+
+AgentResponse response = await agent.RunAsync(
+    "How many kilometers is a marathon (26.2 miles)? And how many pounds is 75 kilograms?");
+
+Console.WriteLine($"Agent: {response.Text}");
+
+/// <summary>
+/// A unit-converter skill defined as a C# class.
+/// </summary>
+/// <remarks>
+/// Class-based skills bundle all components (name, description, body, resources, scripts)
+/// into a single class.
+/// </remarks>
+internal sealed class UnitConverterSkill : AgentClassSkill
+{
+    private IReadOnlyList<AgentSkillResource>? _resources;
+    private IReadOnlyList<AgentSkillScript>? _scripts;
+
+    /// <inheritdoc/>
+    public override AgentSkillFrontmatter Frontmatter { get; } = new(
+        "unit-converter",
+        "Convert between common units using a multiplication factor. Use when asked to convert miles, kilometers, pounds, or kilograms.");
+
+    /// <inheritdoc/>
+    protected override string Instructions => """
+        Use this skill when the user asks to convert between units.
+
+        1. Review the conversion-table resource to find the factor for the requested conversion.
+        2. Use the convert script, passing the value and factor from the table.
+        3. Present the result clearly with both units.
+        """;
+
+    /// <inheritdoc/>
+    public override IReadOnlyList<AgentSkillResource>? Resources => this._resources ??=
+    [
+        CreateResource(
+            "conversion-table",
+            """
+            # Conversion Tables
+
+            Formula: **result = value × factor**
+
+            | From        | To          | Factor   |
+            |-------------|-------------|----------|
+            | miles       | kilometers  | 1.60934  |
+            | kilometers  | miles       | 0.621371 |
+            | pounds      | kilograms   | 0.453592 |
+            | kilograms   | pounds      | 2.20462  |
+            """),
+    ];
+
+    /// <inheritdoc/>
+    public override IReadOnlyList<AgentSkillScript>? Scripts => this._scripts ??=
+    [
+        CreateScript("convert", ConvertUnits),
+    ];
+
+    private static string ConvertUnits(double value, double factor)
+    {
+        double result = Math.Round(value * factor, 4);
+        return JsonSerializer.Serialize(new { value, factor, result });
+    }
+}

dotnet/samples/02-agents/AgentSkills/Agent_Step03_ClassBasedSkills/README.md

@@ -0,0 +1,49 @@
+# Class-Based Agent Skills Sample
+
+This sample demonstrates how to define **Agent Skills as C# classes** using `AgentClassSkill`.
+
+## What it demonstrates
+
+- Creating skills as classes that extend `AgentClassSkill`
+- Bundling name, description, body, resources, and scripts into a single class
+- Using the `AgentSkillsProvider` constructor with class-based skills
+
+## Skills Included
+
+### unit-converter (class-based)
+
+A `UnitConverterSkill` class that converts between common units. Defined in `Program.cs`:
+
+- `conversion-table` — Static resource with factor table
+- `convert` — Script that performs `value × factor` conversion
+
+## Running the Sample
+
+### Prerequisites
+
+- .NET 10.0 SDK
+- Azure OpenAI endpoint with a deployed model
+
+### Setup
+
+```bash
+export AZURE_OPENAI_ENDPOINT="https://your-endpoint.openai.azure.com/"
+export AZURE_OPENAI_DEPLOYMENT_NAME="gpt-4o-mini"
+```
+
+### Run
+
+```bash
+dotnet run
+```
+
+### Expected Output
+
+```
+Converting units with class-based skills
+------------------------------------------------------------
+Agent: Here are your conversions:
+
+1. **26.2 miles → 42.16 km** (a marathon distance)
+2. **75 kg → 165.35 lbs**
+```

dotnet/samples/02-agents/AgentSkills/Agent_Step04_MixedSkills/Agent_Step04_MixedSkills.csproj

@@ -0,0 +1,32 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <NoWarn>$(NoWarn);MAAI001</NoWarn>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Azure.AI.OpenAI" />
+    <PackageReference Include="Azure.Identity" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Compile Include="..\SubprocessScriptRunner.cs" Link="SubprocessScriptRunner.cs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\src\Microsoft.Agents.AI.OpenAI\Microsoft.Agents.AI.OpenAI.csproj" />
+  </ItemGroup>
+
+  <!-- Copy skills directory to output -->
+  <ItemGroup>
+    <None Include="skills\**\*.*">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+</Project>

dotnet/samples/02-agents/AgentSkills/Agent_Step04_MixedSkills/Program.cs

@@ -0,0 +1,149 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// This sample demonstrates an advanced scenario: combining multiple skill types in a single agent
+// using AgentSkillsProviderBuilder. The builder is designed for cases where the simple
+// AgentSkillsProvider constructors are insufficient — for example, when you need to mix skill
+// sources, apply filtering, or configure cross-cutting options in one place.
+//
+// Three different skill sources are registered here:
+// 1. File-based: unit-converter (miles↔km, pounds↔kg) from SKILL.md on disk
+// 2. Code-defined: volume-converter (gallons↔liters) using AgentInlineSkill
+// 3. Class-based: temperature-converter (°F↔°C↔K) using AgentClassSkill
+//
+// For simpler, single-source scenarios, see the earlier steps in this sample series
+// (e.g., Step01 for file-based, Step02 for code-defined, Step03 for class-based).
+
+using System.Text.Json;
+using Azure.AI.OpenAI;
+using Azure.Identity;
+using Microsoft.Agents.AI;
+using OpenAI.Responses;
+
+// --- Configuration ---
+string endpoint = Environment.GetEnvironmentVariable("AZURE_OPENAI_ENDPOINT")
+    ?? throw new InvalidOperationException("AZURE_OPENAI_ENDPOINT is not set.");
+string deploymentName = Environment.GetEnvironmentVariable("AZURE_OPENAI_DEPLOYMENT_NAME") ?? "gpt-4o-mini";
+
+// --- 1. Code-Defined Skill: volume-converter ---
+var volumeConverterSkill = new AgentInlineSkill(
+    name: "volume-converter",
+    description: "Convert between gallons and liters using a multiplication factor.",
+    instructions: """
+        Use this skill when the user asks to convert between gallons and liters.
+
+        1. Review the volume-conversion-table resource to find the correct factor.
+        2. Use the convert-volume script, passing the value and factor.
+        """)
+    .AddResource("volume-conversion-table",
+        """
+        # Volume Conversion Table
+
+        Formula: **result = value × factor**
+
+        | From    | To      | Factor  |
+        |---------|---------|---------|
+        | gallons | liters  | 3.78541 |
+        | liters  | gallons | 0.264172|
+        """)
+    .AddScript("convert-volume", (double value, double factor) =>
+    {
+        double result = Math.Round(value * factor, 4);
+        return JsonSerializer.Serialize(new { value, factor, result });
+    });
+
+// --- 2. Class-Based Skill: temperature-converter ---
+var temperatureConverter = new TemperatureConverterSkill();
+
+// --- 3. Build provider combining all three source types ---
+var skillsProvider = new AgentSkillsProviderBuilder()
+    .UseFileSkill(Path.Combine(AppContext.BaseDirectory, "skills"))    // File-based: unit-converter
+    .UseSkill(volumeConverterSkill)                                    // Code-defined: volume-converter
+    .UseSkill(temperatureConverter)                                     // Class-based: temperature-converter
+    .UseFileScriptRunner(SubprocessScriptRunner.RunAsync)
+    .Build();
+
+// --- Agent Setup ---
+AIAgent agent = new AzureOpenAIClient(new Uri(endpoint), new DefaultAzureCredential())
+    .GetResponsesClient()
+    .AsAIAgent(new ChatClientAgentOptions
+    {
+        Name = "MultiConverterAgent",
+        ChatOptions = new()
+        {
+            Instructions = "You are a helpful assistant that can convert units, volumes, and temperatures.",
+        },
+        AIContextProviders = [skillsProvider],
+    },
+    model: deploymentName);
+
+// --- Example: Use all three skills ---
+Console.WriteLine("Converting with mixed skills (file + code + class)");
+Console.WriteLine(new string('-', 60));
+
+AgentResponse response = await agent.RunAsync(
+    "I need three conversions: " +
+    "1) How many kilometers is a marathon (26.2 miles)? " +
+    "2) How many liters is a 5-gallon bucket? " +
+    "3) What is 98.6°F in Celsius?");
+
+Console.WriteLine($"Agent: {response.Text}");
+
+/// <summary>
+/// A temperature-converter skill defined as a C# class.
+/// </summary>
+internal sealed class TemperatureConverterSkill : AgentClassSkill
+{
+    private IReadOnlyList<AgentSkillResource>? _resources;
+    private IReadOnlyList<AgentSkillScript>? _scripts;
+
+    /// <inheritdoc/>
+    public override AgentSkillFrontmatter Frontmatter { get; } = new(
+        "temperature-converter",
+        "Convert between temperature scales (Fahrenheit, Celsius, Kelvin).");
+
+    /// <inheritdoc/>
+    protected override string Instructions => """
+        Use this skill when the user asks to convert temperatures.
+
+        1. Review the temperature-conversion-formulas resource for the correct formula.
+        2. Use the convert-temperature script, passing the value, source scale, and target scale.
+        3. Present the result clearly with both temperature scales.
+        """;
+
+    /// <inheritdoc/>
+    public override IReadOnlyList<AgentSkillResource>? Resources => this._resources ??=
+    [
+        CreateResource(
+            "temperature-conversion-formulas",
+            """
+            # Temperature Conversion Formulas
+
+            | From        | To          | Formula                   |
+            |-------------|-------------|---------------------------|
+            | Fahrenheit  | Celsius     | °C = (°F − 32) × 5/9     |
+            | Celsius     | Fahrenheit  | °F = (°C × 9/5) + 32     |
+            | Celsius     | Kelvin      | K = °C + 273.15           |
+            | Kelvin      | Celsius     | °C = K − 273.15           |
+            """),
+    ];
+
+    /// <inheritdoc/>
+    public override IReadOnlyList<AgentSkillScript>? Scripts => this._scripts ??=
+    [
+        CreateScript("convert-temperature", ConvertTemperature),
+    ];
+
+    private static string ConvertTemperature(double value, string from, string to)
+    {
+        double result = (from.ToUpperInvariant(), to.ToUpperInvariant()) switch
+        {
+            ("FAHRENHEIT", "CELSIUS") => Math.Round((value - 32) * 5.0 / 9.0, 2),
+            ("CELSIUS", "FAHRENHEIT") => Math.Round(value * 9.0 / 5.0 + 32, 2),
+            ("CELSIUS", "KELVIN") => Math.Round(value + 273.15, 2),
+            ("KELVIN", "CELSIUS") => Math.Round(value - 273.15, 2),
+            _ => throw new ArgumentException($"Unsupported conversion: {from} → {to}")
+        };
+
+        return JsonSerializer.Serialize(new { value, from, to, result });
+    }
+}