fix: update PyRIT repository link from Azure/PyRIT to microsoft/PyRIT

Agent-Logs-Url: https://github.com/microsoft/agent-framework/sessions/830b8ccf-a79c-49b6-90c9-3bb3e740bc06 Co-authored-by: rogerbarreto <19890735+rogerbarreto@users.noreply.github.com>
Initial plan
2026-06-16 21:04:09 +08:00 · 2026-03-28 15:43:29 +00:00 · 2026-03-28 15:42:25 +00:00 · 2026-03-27 21:00:12 +00:00 · 2026-03-27 17:38:23 +00:00 · 2026-03-27 16:27:19 +00:00
320 changed files with 18912 additions and 7617 deletions
@@ -60,9 +60,8 @@ jobs:
    environment: integration
    timeout-minutes: 60
    env:
-      OPENAI_CHAT_MODEL_ID: ${{ vars.OPENAI__CHATMODELID }}
-      OPENAI_RESPONSES_MODEL_ID: ${{ vars.OPENAI__RESPONSESMODELID }}
-      OPENAI_EMBEDDINGS_MODEL_ID: ${{ vars.OPENAI_EMBEDDING_MODEL_ID }}
+      OPENAI_CHAT_MODEL: ${{ vars.OPENAI__CHATMODELID }}
+      OPENAI_RESPONSES_MODEL: ${{ vars.OPENAI__RESPONSESMODELID }}
      OPENAI_MODEL: ${{ vars.OPENAI__RESPONSESMODELID }}
      OPENAI_EMBEDDING_MODEL: ${{ vars.OPENAI_EMBEDDING_MODEL_ID }}
      OPENAI_API_KEY: ${{ secrets.OPENAI__APIKEY }}
@@ -96,10 +95,10 @@ jobs:
    environment: integration
    timeout-minutes: 60
    env:
-      AZURE_OPENAI_CHAT_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__RESPONSESDEPLOYMENTNAME }}
+      AZURE_OPENAI_CHAT_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__CHATDEPLOYMENTNAME }}
      AZURE_OPENAI_RESPONSES_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__RESPONSESDEPLOYMENTNAME }}
      AZURE_OPENAI_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__RESPONSESDEPLOYMENTNAME }}
-      AZURE_OPENAI_EMBEDDING_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__EMBEDDINGDEPLOYMENTNAME }}
+      AZURE_OPENAI_EMBEDDING_DEPLOYMENT_NAME: ${{ vars.AZURE_OPENAI_EMBEDDING_DEPLOYMENT_NAME }}
      AZURE_OPENAI_ENDPOINT: ${{ vars.AZUREOPENAI__ENDPOINT }}
    defaults:
      run:
@@ -126,7 +125,9 @@ jobs:
          uv run pytest --import-mode=importlib
          packages/openai/tests/openai/test_openai_chat_completion_client_azure.py
          packages/openai/tests/openai/test_openai_chat_client_azure.py
+          packages/openai/tests/openai/test_openai_embedding_client_azure.py
          packages/azure-ai/tests/azure_openai
+          --ignore=packages/azure-ai/tests/azure_openai/test_azure_responses_client_foundry.py
          -m integration
          -n logical --dist worksteal
          --timeout=120 --session-timeout=900 --timeout_method thread
@@ -202,15 +203,16 @@ jobs:
    timeout-minutes: 60
    env:
      UV_PYTHON: "3.11"
-      OPENAI_CHAT_MODEL_ID: ${{ vars.OPENAI__CHATMODELID }}
-      OPENAI_RESPONSES_MODEL_ID: ${{ vars.OPENAI__RESPONSESMODELID }}
+      OPENAI_CHAT_MODEL: ${{ vars.OPENAI__CHATMODELID }}
+      OPENAI_RESPONSES_MODEL: ${{ vars.OPENAI__RESPONSESMODELID }}
      OPENAI_MODEL: ${{ vars.OPENAI__RESPONSESMODELID }}
-      OPENAI_API_KEY: ${{ secrets.OPENAI__APIKEY }}
      OPENAI_EMBEDDING_MODEL: ${{ vars.OPENAI_EMBEDDING_MODEL_ID }}
+      OPENAI_API_KEY: ${{ secrets.OPENAI__APIKEY }}
      AZURE_OPENAI_ENDPOINT: ${{ vars.AZUREOPENAI__ENDPOINT }}
      AZURE_OPENAI_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__RESPONSESDEPLOYMENTNAME }}
-      FOUNDRY_MODEL: ${{ vars.AZUREAI__DEPLOYMENTNAME }}
-      FOUNDRY_PROJECT_ENDPOINT: ${{ secrets.AZUREAI__ENDPOINT }}
+      AZURE_OPENAI_CHAT_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__CHATDEPLOYMENTNAME }}
+      FOUNDRY_PROJECT_ENDPOINT: ${{ vars.FOUNDRY_PROJECT_ENDPOINT }}
+      FOUNDRY_MODEL: ${{ vars.FOUNDRY_MODEL }}
      FUNCTIONS_WORKER_RUNTIME: "python"
      DURABLE_TASK_SCHEDULER_CONNECTION_STRING: "Endpoint=http://localhost:8080;TaskHub=default;Authentication=None"
      AzureWebJobsStorage: "UseDevelopmentStorage=true"
@@ -248,17 +250,19 @@ jobs:
          --timeout=360 --session-timeout=900 --timeout_method thread
          --retries 2 --retry-delay 5

-  # Azure AI integration tests
-  python-tests-azure-ai:
-    name: Python Integration Tests - Azure AI
+  # Foundry integration tests
+  python-tests-foundry:
+    name: Python Integration Tests - Foundry
    runs-on: ubuntu-latest
    environment: integration
    timeout-minutes: 60
    env:
      AZURE_AI_PROJECT_ENDPOINT: ${{ secrets.AZUREAI__ENDPOINT }}
      AZURE_AI_MODEL_DEPLOYMENT_NAME: ${{ vars.AZUREAI__DEPLOYMENTNAME }}
-      FOUNDRY_PROJECT_ENDPOINT: ${{ secrets.AZUREAI__ENDPOINT }}
-      FOUNDRY_MODEL: ${{ vars.AZUREAI__DEPLOYMENTNAME }}
+      FOUNDRY_PROJECT_ENDPOINT: ${{ vars.FOUNDRY_PROJECT_ENDPOINT }}
+      FOUNDRY_MODEL: ${{ vars.FOUNDRY_MODEL }}
+      FOUNDRY_AGENT_NAME: ${{ vars.FOUNDRY_AGENT_NAME }}
+      FOUNDRY_AGENT_VERSION: ${{ vars.FOUNDRY_AGENT_VERSION }}
      LOCAL_MCP_URL: ${{ vars.LOCAL_MCP__URL }}
    defaults:
      run:
@@ -282,9 +286,14 @@ jobs:
          subscription-id: ${{ secrets.AZURE_SUBSCRIPTION_ID }}
      - name: Test with pytest
        timeout-minutes: 15
-        run: |
-          uv run --directory packages/azure-ai poe integration-tests -n logical --dist worksteal --timeout=120 --session-timeout=900 --timeout_method thread --retries 2 --retry-delay 5
-          uv run --directory packages/foundry poe integration-tests -n logical --dist worksteal --timeout=120 --session-timeout=900 --timeout_method thread --retries 2 --retry-delay 5
+        run: >
+          uv run pytest --import-mode=importlib
+          packages/azure-ai/tests/azure_openai/test_azure_responses_client_foundry.py
+          packages/foundry/tests
+          -m integration
+          -n logical --dist worksteal
+          --timeout=120 --session-timeout=900 --timeout_method thread
+          --retries 2 --retry-delay 5

  # Azure Cosmos integration tests
  python-tests-cosmos:
@@ -341,7 +350,7 @@ jobs:
        python-tests-azure-openai,
        python-tests-misc-integration,
        python-tests-functions,
-        python-tests-azure-ai,
+        python-tests-foundry,
        python-tests-cosmos
      ]
    steps:
@@ -141,9 +141,8 @@ jobs:
    runs-on: ubuntu-latest
    environment: integration
    env:
-      OPENAI_CHAT_MODEL_ID: ${{ vars.OPENAI__CHATMODELID }}
-      OPENAI_RESPONSES_MODEL_ID: ${{ vars.OPENAI__RESPONSESMODELID }}
-      OPENAI_EMBEDDINGS_MODEL_ID: ${{ vars.OPENAI_EMBEDDING_MODEL_ID }}
+      OPENAI_CHAT_MODEL: ${{ vars.OPENAI__CHATMODELID }}
+      OPENAI_RESPONSES_MODEL: ${{ vars.OPENAI__RESPONSESMODELID }}
      OPENAI_MODEL: ${{ vars.OPENAI__RESPONSESMODELID }}
      OPENAI_EMBEDDING_MODEL: ${{ vars.OPENAI_EMBEDDING_MODEL_ID }}
      OPENAI_API_KEY: ${{ secrets.OPENAI__APIKEY }}
@@ -195,10 +194,10 @@ jobs:
    runs-on: ubuntu-latest
    environment: integration
    env:
-      AZURE_OPENAI_CHAT_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__RESPONSESDEPLOYMENTNAME }}
+      AZURE_OPENAI_CHAT_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__CHATDEPLOYMENTNAME }}
      AZURE_OPENAI_RESPONSES_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__RESPONSESDEPLOYMENTNAME }}
      AZURE_OPENAI_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__RESPONSESDEPLOYMENTNAME }}
-      AZURE_OPENAI_EMBEDDING_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__EMBEDDINGDEPLOYMENTNAME }}
+      AZURE_OPENAI_EMBEDDING_DEPLOYMENT_NAME: ${{ vars.AZURE_OPENAI_EMBEDDING_DEPLOYMENT_NAME }}
      AZURE_OPENAI_ENDPOINT: ${{ vars.AZUREOPENAI__ENDPOINT }}
    defaults:
      run:
@@ -223,7 +222,9 @@ jobs:
          uv run pytest --import-mode=importlib
          packages/openai/tests/openai/test_openai_chat_completion_client_azure.py
          packages/openai/tests/openai/test_openai_chat_client_azure.py
+          packages/openai/tests/openai/test_openai_embedding_client_azure.py
          packages/azure-ai/tests/azure_openai
+          --ignore=packages/azure-ai/tests/azure_openai/test_azure_responses_client_foundry.py
          -m integration
          -n logical --dist worksteal
          --timeout=120 --session-timeout=900 --timeout_method thread
@@ -333,15 +334,16 @@ jobs:
    environment: integration
    env:
      UV_PYTHON: "3.11"
-      OPENAI_CHAT_MODEL_ID: ${{ vars.OPENAI__CHATMODELID }}
-      OPENAI_RESPONSES_MODEL_ID: ${{ vars.OPENAI__RESPONSESMODELID }}
+      OPENAI_CHAT_MODEL: ${{ vars.OPENAI__CHATMODELID }}
+      OPENAI_RESPONSES_MODEL: ${{ vars.OPENAI__RESPONSESMODELID }}
      OPENAI_MODEL: ${{ vars.OPENAI__RESPONSESMODELID }}
-      OPENAI_API_KEY: ${{ secrets.OPENAI__APIKEY }}
      OPENAI_EMBEDDING_MODEL: ${{ vars.OPENAI_EMBEDDING_MODEL_ID }}
+      OPENAI_API_KEY: ${{ secrets.OPENAI__APIKEY }}
      AZURE_OPENAI_ENDPOINT: ${{ vars.AZUREOPENAI__ENDPOINT }}
      AZURE_OPENAI_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__RESPONSESDEPLOYMENTNAME }}
-      FOUNDRY_MODEL: ${{ vars.AZUREAI__DEPLOYMENTNAME }}
-      FOUNDRY_PROJECT_ENDPOINT: ${{ secrets.AZUREAI__ENDPOINT }}
+      AZURE_OPENAI_CHAT_DEPLOYMENT_NAME: ${{ vars.AZUREOPENAI__CHATDEPLOYMENTNAME }}
+      FOUNDRY_PROJECT_ENDPOINT: ${{ vars.FOUNDRY_PROJECT_ENDPOINT }}
+      FOUNDRY_MODEL: ${{ vars.FOUNDRY_MODEL }}
      FUNCTIONS_WORKER_RUNTIME: "python"
      DURABLE_TASK_SCHEDULER_CONNECTION_STRING: "Endpoint=http://localhost:8080;TaskHub=default;Authentication=None"
      AzureWebJobsStorage: "UseDevelopmentStorage=true"
@@ -387,8 +389,8 @@ jobs:
          fail-on-empty: false
          title: Functions integration test results

-  python-tests-azure-ai:
-    name: Python Tests - Azure AI
+  python-tests-foundry:
+    name: Python Integration Tests - Foundry
    needs: paths-filter
    if: >
      github.event_name != 'pull_request' &&
@@ -401,8 +403,10 @@ jobs:
    env:
      AZURE_AI_PROJECT_ENDPOINT: ${{ secrets.AZUREAI__ENDPOINT }}
      AZURE_AI_MODEL_DEPLOYMENT_NAME: ${{ vars.AZUREAI__DEPLOYMENTNAME }}
-      FOUNDRY_PROJECT_ENDPOINT: ${{ secrets.AZUREAI__ENDPOINT }}
-      FOUNDRY_MODEL: ${{ vars.AZUREAI__DEPLOYMENTNAME }}
+      FOUNDRY_PROJECT_ENDPOINT: ${{ vars.FOUNDRY_PROJECT_ENDPOINT }}
+      FOUNDRY_MODEL: ${{ vars.FOUNDRY_MODEL }}
+      FOUNDRY_AGENT_NAME: ${{ vars.FOUNDRY_AGENT_NAME }}
+      FOUNDRY_AGENT_VERSION: ${{ vars.FOUNDRY_AGENT_VERSION }}
      LOCAL_MCP_URL: ${{ vars.LOCAL_MCP__URL }}
    defaults:
      run:
@@ -424,9 +428,14 @@ jobs:
          subscription-id: ${{ secrets.AZURE_SUBSCRIPTION_ID }}
      - name: Test with pytest
        timeout-minutes: 15
-        run: |
-          uv run --directory packages/azure-ai poe integration-tests -n logical --dist worksteal --timeout=120 --session-timeout=900 --timeout_method thread --retries 2 --retry-delay 5
-          uv run --directory packages/foundry poe integration-tests -n logical --dist worksteal --timeout=120 --session-timeout=900 --timeout_method thread --retries 2 --retry-delay 5
+        run: >
+          uv run pytest --import-mode=importlib
+          packages/azure-ai/tests/azure_openai/test_azure_responses_client_foundry.py
+          packages/foundry/tests
+          -m integration
+          -n logical --dist worksteal
+          --timeout=120 --session-timeout=900 --timeout_method thread
+          --retries 2 --retry-delay 5
        working-directory: ./python
      - name: Test Azure AI samples
        timeout-minutes: 10
@@ -513,7 +522,7 @@ jobs:
        python-tests-azure-openai,
        python-tests-misc-integration,
        python-tests-functions,
-        python-tests-azure-ai,
+        python-tests-foundry,
        python-tests-cosmos,
      ]
    steps:
@@ -0,0 +1,960 @@
+status: proposed
+date: 2026-03-23
+contact: sergeymenshykh
+deciders: rbarreto, westey-m, eavanvalkenburg
+---
+
+# Agent Skills: Multi-Source Architecture
+
+## Context and Problem Statement
+
+The Agent Framework needs a skills system that lets agents discover and use domain-specific knowledge, reference documents, and executable scripts. Skills can originate from different sources — filesystem directories (SKILL.md files), inline C# code, or reusable class libraries — and the framework must support all three uniformly while allowing extensibility, composition, and filtering.
+
+## Decision Drivers
+
+- Skills must be definable from multiple sources: filesystem, inline code, reusable classes, etc
+- Common abstractions are needed so the provider and builder work uniformly regardless of skill origin
+- File-based scripts must support user-defined executors, enabling custom runtimes and languages; code/class-based scripts execute in-process as C# delegates
+- Skills must be filterable so consumers can include or exclude specific skills based on defined criteria
+- Multiple skill sources must be composable into a single provider
+- It must be possible to add custom skill sources (e.g., databases, REST APIs, package registries) by implementing a common abstraction
+
+## Architecture
+
+### Model-Facing Tools
+
+Skills are presented to the model as up to three tools that progressively disclose skill content. The system prompt lists available skill names and descriptions; the model then calls these tools on demand:
+
+- **`load_skill(skillName)`** — returns the full skill body (instructions, listed resources, listed scripts)
+- **`read_skill_resource(skillName, resourceName)`** — reads a supplementary resource (file-based or code-defined) associated with a skill
+- **`run_skill_script(skillName, scriptName, arguments?)`** — executes a script associated with a skill; only registered when at least one skill contains scripts
+
+Each tool delegates to the corresponding method on the resolved `AgentSkill` — calling `Resource.ReadAsync()` or `Script.RunAsync()` respectively.
+
+If skills have no scripts defined, the `run_skill_script` tool is **not advertised** to the model and instructions related to script execution are **not included** in the default skills instructions.
+
+### Abstract Base Types
+
+The architecture defines four abstract base types that all skill variants implement:
+
+```csharp
+public abstract class AgentSkill
+{
+    public abstract AgentSkillFrontmatter Frontmatter { get; }
+    public abstract string Content { get; }
+    public abstract IReadOnlyList<AgentSkillResource>? Resources { get; }
+    public abstract IReadOnlyList<AgentSkillScript>? Scripts { get; }
+}
+
+public abstract class AgentSkillResource
+{
+    public string Name { get; }
+    public string? Description { get; }
+    public abstract Task<object?> ReadAsync(IServiceProvider? serviceProvider = null, CancellationToken cancellationToken = default);
+}
+
+public abstract class AgentSkillScript
+{
+    public string Name { get; }
+    public string? Description { get; }
+    public abstract Task<object?> RunAsync(AgentSkill skill, AIFunctionArguments arguments, CancellationToken cancellationToken = default);
+}
+
+public abstract class AgentSkillsSource
+{
+    public abstract Task<IList<AgentSkill>> GetSkillsAsync(CancellationToken cancellationToken = default);
+}
+```
+
+Skill metadata is captured via `AgentSkillFrontmatter`:
+
+```csharp
+public sealed class AgentSkillFrontmatter
+{
+    public AgentSkillFrontmatter(string name, string description) { ... }
+
+    public string Name { get; }
+    public string Description { get; }
+    public string? License { get; set; }
+    public string? Compatibility { get; set; }
+    public string? AllowedTools { get; set; }
+    public AdditionalPropertiesDictionary? Metadata { get; set; }
+}
+```
+
+The type hierarchy at a glance:
+
+```
+AgentSkill (abstract)                   AgentSkillsSource (abstract)
+├── AgentFileSkill                      ├── AgentFileSkillsSource          (public)
+└── [Programmatic]                      ├── AgentInMemorySkillsSource      (public)
+    ├── AgentInlineSkill                ├── AggregatingAgentSkillsSource     (public)
+    └── AgentClassSkill (abstract)      └── DelegatingAgentSkillsSource    (abstract, public)
+                                            ├── FilteringAgentSkillsSource  (public)
+AgentSkillResource (abstract)               ├── CachingAgentSkillsSource    (public)
+├── AgentFileSkillResource                  └── DeduplicatingAgentSkillsSource (public)
+└── AgentInlineSkillResource
+                                        AgentSkillScript (abstract)
+                                        ├── AgentFileSkillScript
+                                        └── AgentInlineSkillScript
+```
+
+There are two top-level categories of skills:
+
+1. **File-Based Skills** — discovered from `SKILL.md` files on the filesystem. Resources and scripts are files in subdirectories.
+2. **Programmatic Skills** — defined in C# code. These are further divided into:
+   - **Inline Skills** — built at runtime via the `AgentInlineSkill` class and its fluent API. Ideal for quick, agent-specific skill definitions.
+   - **Class-Based Skills** — defined as reusable C# classes that subclass `AgentClassSkill`. Ideal for packaging skills as shared libraries or NuGet packages.
+
+Both programmatic skill types use `AgentInlineSkillResource` and `AgentInlineSkillScript` for their resources and scripts. They are typically served by `AgentInMemorySkillsSource`, which accepts any `AgentSkill` and is not limited to programmatic skills.
+
+### File-Based Skills
+
+File-based skills are authored as `SKILL.md` files on disk. Resources and scripts are discovered from corresponding subfolders within the skill directory.
+
+**`AgentFileSkill`** — A filesystem-based skill discovered from a directory containing a `SKILL.md` file. Parsed from YAML frontmatter; content is the raw markdown body. Resources and scripts are discovered from files in corresponding subfolders:
+
+```csharp
+public sealed class AgentFileSkill : AgentSkill
+{
+    internal AgentFileSkill(
+        AgentSkillFrontmatter frontmatter, string content, string path,
+        IReadOnlyList<AgentSkillResource>? resources = null,
+        IReadOnlyList<AgentSkillScript>? scripts = null) { ... }
+}
+```
+
+**`AgentFileSkillResource`** — A file-based skill resource. Reads content from a file on disk relative to the skill directory:
+
+```csharp
+internal sealed class AgentFileSkillResource : AgentSkillResource
+{
+    public AgentFileSkillResource(string name, string fullPath) { ... }
+
+    public string FullPath { get; }
+
+    public override Task<object?> ReadAsync(IServiceProvider? serviceProvider = null, CancellationToken cancellationToken = default)
+    {
+        return File.ReadAllTextAsync(FullPath, Encoding.UTF8, cancellationToken);
+    }
+}
+```
+
+**`AgentFileSkillScript`** — A file-based skill script that represents a script file on disk. Delegates execution to an external `AgentFileSkillScriptRunner` callback (e.g., runs Python/shell via `Process.Start`). Throws `NotSupportedException` if no executor is configured:
+
+```csharp
+public delegate Task<object?> AgentFileSkillScriptRunner(
+    AgentFileSkill skill, AgentFileSkillScript script,
+    AIFunctionArguments arguments, CancellationToken cancellationToken);
+
+public sealed class AgentFileSkillScript : AgentSkillScript
+{
+    private readonly AgentFileSkillScriptRunner _executor;
+
+    internal AgentFileSkillScript(string name, string fullPath, AgentFileSkillScriptRunner executor)
+        : base(name) { ... }
+
+    public override async Task<object?> RunAsync(AgentSkill skill, AIFunctionArguments arguments, ...)
+    {
+
+        return await _executor(fileSkill, this, arguments, cancellationToken);
+    }
+}
+```
+
+The executor can be provided at the **provider level** via `AgentSkillsProviderBuilder.UseFileScriptRunner(executor)` and optionally overridden for a **particular file skill** or for a **set of skills** at the file skill source level, giving fine-grained control over how different scripts are executed.
+
+**`AgentFileSkillsSource`** — A skill source that discovers skills from filesystem directories containing `SKILL.md` files. Recursively scans directories (max 2 levels), validates frontmatter, and enforces path traversal and symlink security checks:
+
+```csharp
+public sealed partial class AgentFileSkillsSource : AgentSkillsSource
+{
+    public AgentFileSkillsSource(
+        IEnumerable<string> skillPaths,
+        AgentFileSkillScriptRunner scriptRunner,
+        AgentFileSkillsSourceOptions? options = null,
+        ILoggerFactory? loggerFactory = null) { ... }
+}
+```
+
+**`AgentFileSkillsSourceOptions`** — Configuration options for `AgentFileSkillsSource`. Allows customizing the allowed file extensions for resources and scripts without adding constructor parameters:
+
+```csharp
+public sealed class AgentFileSkillsSourceOptions
+{
+    public IEnumerable<string>? AllowedResourceExtensions { get; set; }
+    public IEnumerable<string>? AllowedScriptExtensions { get; set; }
+}
+```
+
+**Example** — A file-based skill on disk and how it is added to a source:
+
+```
+skills/
+└── unit-converter/
+    ├── SKILL.md               # frontmatter + instructions
+    ├── resources/
+    │   └── conversion-table.csv   # discovered as a resource
+    └── scripts/
+        └── convert.py             # discovered as a script
+```
+
+```csharp
+var source = new AgentFileSkillsSource(skillPaths: ["./skills"], scriptRunner: SubprocessScriptRunner.RunAsync);
+
+var provider = new AgentSkillsProvider(source);
+
+AIAgent agent = chatClient.AsAIAgent(new ChatClientAgentOptions
+{
+    AIContextProviders = [provider],
+});
+```
+
+### Programmatic Skills
+
+Programmatic skills are defined in C# code rather than discovered from the filesystem. There are two kinds: **inline** and **class-based**. Both use `AgentInlineSkillResource` and `AgentInlineSkillScript` for resources and scripts, and are held by a single `AgentInMemorySkillsSource`.
+
+**`AgentInMemorySkillsSource`** — A general-purpose skill source that holds any `AgentSkill` instances in memory. Although commonly used for programmatic skills (`AgentInlineSkill` and `AgentClassSkill`), it accepts any `AgentSkill` subclass and is not restricted to code-defined skills:
+
+```csharp
+public sealed class AgentInMemorySkillsSource : AgentSkillsSource
+{
+    public AgentInMemorySkillsSource(
+        IEnumerable<AgentSkill> skills,
+        ILoggerFactory? loggerFactory = null) { ... }
+}
+```
+
+#### Inline Skills
+
+Inline skills are built at runtime via the `AgentInlineSkill` class and its fluent API. They are ideal for quick, agent-specific skill definitions where a full class hierarchy would be overkill.
+
+**`AgentInlineSkill`** — A skill defined entirely in code. Resources can be static values or functions; scripts are always functions. Constructed with name, description, and instructions, then extended with resources and scripts:
+
+```csharp
+public sealed class AgentInlineSkill : AgentSkill
+{
+    public AgentInlineSkill(string name, string description, string instructions, string? license = null, string? compatibility = null, ...) { ... }
+    public AgentInlineSkill(AgentSkillFrontmatter frontmatter, string instructions) { ... }
+
+    public AgentInlineSkill AddResource(object value, string name, string? description = null);
+    public AgentInlineSkill AddResource(Delegate handler, string name, string? description = null);
+    public AgentInlineSkill AddScript(Delegate handler, string name, string? description = null);
+}
+```
+
+**`AgentInlineSkillResource`** — A skill resource that wraps a static value:
+
+```csharp
+public sealed class AgentInlineSkillResource : AgentSkillResource
+{
+    public AgentInlineSkillResource(object value, string name, string? description = null)
+        : base(name, description)
+    {
+        _value = value;
+    }
+
+    public override Task<object?> ReadAsync(IServiceProvider? serviceProvider = null, CancellationToken cancellationToken = default)
+    {
+        return Task.FromResult<object?>(_value);
+    }
+}
+```
+
+**`AgentInlineSkillResource`** — A skill resource backed by a delegate. The delegate is invoked via an `AIFunction` each time `ReadAsync` is called, producing a dynamic (computed) value:
+
+```csharp
+public sealed class AgentInlineSkillResource : AgentSkillResource
+{
+    public AgentInlineSkillResource(Delegate handler, string name, string? description = null)
+        : base(name, description)
+    {
+        _function = AIFunctionFactory.Create(handler, name: name);
+    }
+
+    public override async Task<object?> ReadAsync(IServiceProvider? serviceProvider = null, CancellationToken cancellationToken = default)
+    {
+        return await _function.InvokeAsync(new AIFunctionArguments() { Services = serviceProvider }, cancellationToken);
+    }
+}
+```
+
+**`AgentInlineSkillScript`** — A skill script backed by a delegate via an `AIFunction`:
+
+```csharp
+public sealed class AgentInlineSkillScript : AgentSkillScript
+{
+    private readonly AIFunction _function;
+
+    public AgentInlineSkillScript(Delegate handler, string name, string? description = null)
+        : base(name, description)
+    {
+        _function = AIFunctionFactory.Create(handler, name: name);
+    }
+
+    public JsonElement? ParametersSchema => _function.JsonSchema;
+
+    public override async Task<object?> RunAsync(AgentSkill skill, AIFunctionArguments arguments, ...)
+    {
+        return await _function.InvokeAsync(arguments, cancellationToken);
+    }
+}
+```
+
+**Example** — Creating an inline skill with a resource and script, then adding it to a source:
+
+```csharp
+var skill = new AgentInlineSkill(
+        name: "unit-converter",
+        description: "Converts between measurement units.",
+        instructions: """
+            Use this skill to convert values between metric and imperial units.
+            Refer to the conversion-table resource for supported unit pairs.
+            Run the convert script to perform conversions.
+            """
+    )
+    .AddResource("kg=2.205lb, m=3.281ft, L=0.264gal", "conversion-table", "Supported unit pairs")
+    .AddScript(Convert, "convert", "Converts a value between units");
+
+var source = new AgentInMemorySkillsSource([skill]);
+
+var provider = new AgentSkillsProvider(source);
+
+AIAgent agent = chatClient.AsAIAgent(new ChatClientAgentOptions
+{
+    AIContextProviders = [provider],
+});
+
+static string Convert(double value, double factor)
+    => JsonSerializer.Serialize(new { result = Math.Round(value * factor, 4) });
+```
+
+#### Class-Based Skills
+
+Class-based skills are designed for packaging skills as reusable libraries. Users subclass `AgentClassSkill` and override properties. Unlike inline skills, class-based skills are self-contained, can live in shared libraries or NuGet packages, and are well-suited for dependency injection.
+
+**`AgentClassSkill`** — An abstract base class for defining skills as reusable C# classes that bundle all skill components (frontmatter, instructions, resources, scripts) together. Designed for packaging skills as distributable libraries:
+
+```csharp
+public abstract class AgentClassSkill : AgentSkill
+{
+    public abstract string Instructions { get; }
+
+    // Content is auto-synthesized from Frontmatter + Instructions + Resources + Scripts
+    public override string Content =>
+        SkillContentBuilder.BuildContent(Frontmatter.Name, Frontmatter.Description,
+            SkillContentBuilder.BuildBody(Instructions, Resources, Scripts));
+}
+```
+
+**Example** — Defining a class-based skill and adding it to a source:
+
+```csharp
+public class UnitConverterSkill : AgentClassSkill
+{
+    public override AgentSkillFrontmatter Frontmatter { get; } =
+        new("unit-converter", "Converts between measurement units.");
+
+    public override string Instructions => """
+        Use this skill to convert values between metric and imperial units.
+        Refer to the conversion-table resource for supported unit pairs.
+        Run the convert script to perform conversions.
+        """;
+
+    public override IReadOnlyList<AgentSkillResource>? Resources { get; } =
+    [
+        new AgentInlineSkillResource("kg=2.205lb, m=3.281ft", "conversion-table"),
+    ];
+
+    public override IReadOnlyList<AgentSkillScript>? Scripts { get; } =
+    [
+        new AgentInlineSkillScript(Convert, "convert"),
+    ];
+
+    private static string Convert(double value, double factor)
+        => JsonSerializer.Serialize(new { result = Math.Round(value * factor, 4) });
+}
+
+var source = new AgentInMemorySkillsSource([new UnitConverterSkill()]);
+
+var provider = new AgentSkillsProvider(source);
+
+AIAgent agent = chatClient.AsAIAgent(new ChatClientAgentOptions
+{
+    AIContextProviders = [provider],
+});
+```
+
+## Filtering, Caching, and Deduplication
+
+The following subsections present alternative approaches for handling filtering, caching, and deduplication of skills across multiple sources.
+
+### Via Composition
+
+In this approach, the `AgentSkillsProvider` accepts a **single** `AgentSkillsSource`. Multiple sources are composed externally via an aggregate source, and cross-cutting concerns like filtering, caching, and deduplication are implemented as **source decorators** — subclasses of `DelegatingAgentSkillsSource` that intercept `GetSkillsAsync()`.
+
+**`FilteringAgentSkillsSource`** — A decorator that applies filter logic before returning results. The decorator pattern keeps filtering orthogonal to source implementations and allows composing multiple filters:
+
+```csharp
+public sealed class FilteringAgentSkillsSource : DelegatingAgentSkillsSource
+{
+    private readonly Func<AgentSkill, bool> _predicate;
+
+    public FilteringAgentSkillsSource(AgentSkillsSource innerSource, Func<AgentSkill, bool> predicate)
+        : base(innerSource)
+    {
+        _predicate = predicate;
+    }
+
+    public override async Task<IList<AgentSkill>> GetSkillsAsync(CancellationToken cancellationToken = default)
+    {
+        var skills = await this.InnerSource.GetSkillsAsync(cancellationToken);
+        return skills.Where(_predicate).ToList();
+    }
+}
+```
+
+**`CachingAgentSkillsSource`** — A decorator that caches skills after the first load, keeping the provider stateless and giving consumers control over caching granularity per source. For example, file-based skills (expensive to discover) can be cached while code-defined skills remain uncached:
+
+```csharp
+public sealed class CachingAgentSkillsSource : DelegatingAgentSkillsSource
+{
+    private IList<AgentSkill>? _cached;
+
+    public CachingAgentSkillsSource(AgentSkillsSource innerSource)
+        : base(innerSource)
+    {
+    }
+
+    public override async Task<IList<AgentSkill>> GetSkillsAsync(CancellationToken cancellationToken = default)
+    {
+        return _cached ??= await this.InnerSource.GetSkillsAsync(cancellationToken);
+    }
+}
+```
+
+**Deduplication** is similarly implemented as a decorator (`DeduplicatingAgentSkillsSource`) that deduplicates by name (case-insensitive, first-one-wins) and logs a warning for skipped duplicates.
+
+**Example** — Combining file-based and code-defined sources with filtering and caching:
+
+```csharp
+var fileSource = new CachingAgentSkillsSource(new AgentFileSkillsSource(["./skills"]));
+var codeSource = new AgentInMemorySkillsSource([myCodeSkill]);
+
+var compositeSource = new FilteringAgentSkillsSource(
+    new AggregatingAgentSkillsSource([fileSource, codeSource]),
+    filter: s => s.Frontmatter.Name != "internal");
+
+var provider = new AgentSkillsProvider(compositeSource);
+
+AIAgent agent = chatClient.AsAIAgent(new ChatClientAgentOptions
+{
+    AIContextProviders = [provider],
+});
+```
+
+**Pros:**
+- Clean single-responsibility: the provider serves skills, sources provide them.
+- Caching, filtering, and deduplication are composable as source decorators — each concern is a separate, testable wrapper.
+
+**Cons:**
+- DI is less flexible: multiple `AgentSkillsSource` implementations registered in the container cannot be auto-injected into the provider. The consumer must manually compose them via an aggregate source.
+- Increased public API surface: requires additional public classes (aggregate source, caching decorators, filtering decorators) that consumers need to learn and use.
+
+### Via AgentSkillsProvider
+
+In this approach, the `AgentSkillsProvider` accepts **`IEnumerable<AgentSkillsSource>`** and handles aggregation, filtering, caching, and deduplication internally.
+
+The provider aggregates skills from all registered sources, deduplicates by name (case-insensitive, first-one-wins), caches the result after the first load, and optionally applies filtering via a predicate on `AgentSkillsProviderOptions`. Duplicate skill names are logged as warnings.
+
+**Example** — Registering multiple sources directly with the provider:
+
+```csharp
+// Conceptual example — in practice, use AgentSkillsProviderBuilder
+var fileSource = new AgentFileSkillsSource(["./skills"]);
+var codeSource = new AgentInMemorySkillsSource([myCodeSkill]);
+
+var provider = new AgentSkillsProvider(
+    sources: [fileSource, codeSource],
+    options: new AgentSkillsProviderOptions
+    {
+        Filter = s => s.Frontmatter.Name != "internal",
+    });
+
+AIAgent agent = chatClient.AsAIAgent(new ChatClientAgentOptions
+{
+    AIContextProviders = [provider],
+});
+```
+
+**Pros:**
+- DI-friendly: register multiple `AgentSkillsSource` implementations in the container, and they are all auto-injected into `AgentSkillsProvider` via `IEnumerable<AgentSkillsSource>`.
+- Smaller public API surface: no need for aggregate source, caching decorators, or filtering decorator classes — these concerns are handled internally by the provider.
+
+**Cons:**
+- The provider takes on multiple responsibilities — aggregation, caching, deduplication, and filtering.
+- Less granular caching control: caching is all-or-nothing across sources rather than per-source as with decorators.
+- Less extensible: new behaviors (e.g., ordering, TTL expiration) require modifying the provider rather than adding a decorator.
+
+### Builder Pattern
+
+**`AgentSkillsProviderBuilder`** provides a fluent API for composing skills from multiple sources. The builder centralizes configuration — script executors, approval callbacks, prompt templates, and filtering — so consumers don't need to know the underlying source types.
+
+The builder internally decides how to wire up the object graph: it creates the appropriate source instances, applies caching and filtering, and returns a fully configured `AgentSkillsProvider`. This keeps the setup code concise while still allowing fine-grained control when needed.
+
+**Example** — Using the builder to combine multiple source types with configuration:
+
+```csharp
+var provider = new AgentSkillsProviderBuilder()
+    .UseFileSkill("./skills")                           // file-based source
+    .UseInlineSkills(codeSkill)                            // code-defined source
+    .UseClassSkills(new ClassSkill())                    // class-based source
+    .UseFileScriptRunner(SubprocessScriptRunner.RunAsync) // script runner
+    .UseScriptApproval()                                // optional human-in-the-loop
+    .UsePromptTemplate(customTemplate)                  // optional prompt customization
+    .UseFilter(s => s.Frontmatter.Name != "internal")   // optional skill filtering
+    .Build();
+
+AIAgent agent = chatClient.AsAIAgent(new ChatClientAgentOptions
+{
+    AIContextProviders = [provider],
+});
+```
+
+## Adding a Custom Skill Type
+
+The skills framework is designed for extensibility. While file-based and inline skills cover common
+scenarios, you can introduce entirely new skill types by subclassing the four base classes:
+
+| Base class            | Purpose                                             |
+|-----------------------|-----------------------------------------------------|
+| `AgentSkillsSource`   | Discovers and loads skills from a particular origin  |
+| `AgentSkill`          | Holds metadata, content, resources, and scripts      |
+| `AgentSkillResource`  | Provides supplementary content to a skill            |
+| `AgentSkillScript`    | Represents an executable action within a skill       |
+
+The example below implements a **cloud-based skill type** where skills, resources, and scripts are
+all stored in and executed through a remote cloud service (e.g., Azure Blob Storage + Azure Functions).
+
+### Step 1 — Define a custom resource
+
+A `CloudSkillResource` reads resource content from a cloud storage endpoint instead of the local
+filesystem:
+
+```csharp
+/// <summary>
+/// A skill resource backed by a cloud storage endpoint.
+/// </summary>
+public sealed class CloudSkillResource : AgentSkillResource
+{
+    private readonly HttpClient _httpClient;
+
+    public CloudSkillResource(string name, Uri blobUri, HttpClient httpClient, string? description = null)
+        : base(name, description)
+    {
+        BlobUri = blobUri ?? throw new ArgumentNullException(nameof(blobUri));
+        _httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
+    }
+
+    /// <summary>
+    /// Gets the URI of the cloud blob that holds this resource's content.
+    /// </summary>
+    public Uri BlobUri { get; }
+
+    /// <inheritdoc/>
+    public override async Task<object?> ReadAsync(
+        IServiceProvider? serviceProvider = null,
+        CancellationToken cancellationToken = default)
+    {
+        return await _httpClient.GetStringAsync(BlobUri, cancellationToken).ConfigureAwait(false);
+    }
+}
+```
+
+### Step 2 — Define a custom script
+
+A `CloudSkillScript` executes a script by calling a cloud function endpoint, passing arguments as
+the request body:
+
+```csharp
+/// <summary>
+/// A skill script executed via a cloud function endpoint.
+/// </summary>
+public sealed class CloudSkillScript : AgentSkillScript
+{
+    private readonly HttpClient _httpClient;
+
+    public CloudSkillScript(string name, Uri functionUri, HttpClient httpClient, string? description = null)
+        : base(name, description)
+    {
+        FunctionUri = functionUri ?? throw new ArgumentNullException(nameof(functionUri));
+        _httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
+    }
+
+    /// <summary>
+    /// Gets the URI of the cloud function that runs this script.
+    /// </summary>
+    public Uri FunctionUri { get; }
+
+    /// <inheritdoc/>
+    public override async Task<object?> RunAsync(
+        AgentSkill skill,
+        AIFunctionArguments arguments,
+        CancellationToken cancellationToken = default)
+    {
+        var json = JsonSerializer.Serialize(arguments);
+        using var content = new StringContent(json, Encoding.UTF8, "application/json");
+        var response = await _httpClient.PostAsync(FunctionUri, content, cancellationToken)
+            .ConfigureAwait(false);
+        response.EnsureSuccessStatusCode();
+        return await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+    }
+}
+```
+
+### Step 3 — Define a custom skill
+
+A `CloudSkill` bundles cloud-specific metadata (e.g., the base endpoint) with the standard skill
+shape:
+
+```csharp
+/// <summary>
+/// An <see cref="AgentSkill"/> whose content, resources, and scripts are stored in a cloud service.
+/// </summary>
+public sealed class CloudSkill : AgentSkill
+{
+    public CloudSkill(
+        AgentSkillFrontmatter frontmatter,
+        string content,
+        Uri endpoint,
+        IReadOnlyList<AgentSkillResource>? resources = null,
+        IReadOnlyList<AgentSkillScript>? scripts = null)
+    {
+        Frontmatter = frontmatter ?? throw new ArgumentNullException(nameof(frontmatter));
+        Content = content ?? throw new ArgumentNullException(nameof(content));
+        Endpoint = endpoint ?? throw new ArgumentNullException(nameof(endpoint));
+        Resources = resources;
+        Scripts = scripts;
+    }
+
+    /// <inheritdoc/>
+    public override AgentSkillFrontmatter Frontmatter { get; }
+
+    /// <inheritdoc/>
+    public override string Content { get; }
+
+    /// <summary>
+    /// Gets the base cloud endpoint for this skill.
+    /// </summary>
+    public Uri Endpoint { get; }
+
+    /// <inheritdoc/>
+    public override IReadOnlyList<AgentSkillResource>? Resources { get; }
+
+    /// <inheritdoc/>
+    public override IReadOnlyList<AgentSkillScript>? Scripts { get; }
+}
+```
+
+### Step 4 — Define a custom source
+
+A `CloudSkillsSource` discovers skills from a cloud catalog API and constructs `CloudSkill`
+instances with their associated resources and scripts:
+
+```csharp
+/// <summary>
+/// A skill source that discovers and loads skills from a cloud catalog API.
+/// </summary>
+public sealed class CloudSkillsSource : AgentSkillsSource
+{
+    private readonly Uri _catalogUri;
+    private readonly HttpClient _httpClient;
+
+    public CloudSkillsSource(Uri catalogUri, HttpClient httpClient)
+    {
+        _catalogUri = catalogUri ?? throw new ArgumentNullException(nameof(catalogUri));
+        _httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
+    }
+
+    /// <inheritdoc/>
+    public override async Task<IList<AgentSkill>> GetSkillsAsync(
+        CancellationToken cancellationToken = default)
+    {
+        // Fetch the skill catalog from the cloud service.
+        var json = await _httpClient.GetStringAsync(_catalogUri, cancellationToken)
+            .ConfigureAwait(false);
+        var catalog = JsonSerializer.Deserialize<CloudSkillCatalog>(json)!;
+
+        var skills = new List<AgentSkill>();
+
+        foreach (var entry in catalog.Skills)
+        {
+            var frontmatter = new AgentSkillFrontmatter(entry.Name, entry.Description);
+
+            // Build cloud-backed resources.
+            var resources = entry.Resources
+                .Select(r => new CloudSkillResource(r.Name, r.BlobUri, _httpClient, r.Description))
+                .ToList<AgentSkillResource>();
+
+            // Build cloud-backed scripts.
+            var scripts = entry.Scripts
+                .Select(s => new CloudSkillScript(s.Name, s.FunctionUri, _httpClient, s.Description))
+                .ToList<AgentSkillScript>();
+
+            skills.Add(new CloudSkill(frontmatter, entry.Content, entry.Endpoint, resources, scripts));
+        }
+
+        return skills;
+    }
+}
+```
+
+### Step 5 — Register with the builder
+
+Use `UseSource` to wire the custom source into the provider:
+
+```csharp
+var httpClient = new HttpClient();
+
+var provider = new AgentSkillsProviderBuilder()
+    .UseSource(new CloudSkillsSource(
+        new Uri("https://my-service.example.com/skills/catalog"),
+        httpClient))
+    // Mix with other source types if needed:
+    .UseFileSkill("/local/skills", scriptRunner)
+    .UseInlineSkills(someInlineSkill)
+    .Build();
+```
+
+The `AgentSkillsProvider` handles all skill types uniformly — any combination of file-based, inline,
+class-based, and custom skills can coexist in the same provider. Custom skills automatically
+participate in the model-facing tools (`load_skill`, `read_skill_resource`, `run_skill_script`),
+filtering, deduplication, and caching — no additional integration work is required.
+
+## Script Representation: `AgentSkillScript` vs `AIFunction`
+
+Two approaches were considered for representing executable scripts within skills:
+
+### Option A — Custom `AgentSkillScript` abstract base class (original design)
+
+Scripts are modeled as a custom `AgentSkillScript` abstract class with `Name`, `Description`, and
+`RunAsync(AgentSkill, AIFunctionArguments, CancellationToken)`. Concrete implementations:
+`AgentInlineSkillScript` (wraps a delegate/`AIFunction`) and `AgentFileSkillScript` (wraps a file path + executor delegate).
+
+```csharp
+// Base type
+public abstract class AgentSkillScript
+{
+    public string Name { get; }
+    public string? Description { get; }
+    public abstract Task<object?> RunAsync(AgentSkill skill, AIFunctionArguments arguments, CancellationToken cancellationToken = default);
+}
+
+// AgentSkill exposes scripts as:
+public abstract IReadOnlyList<AgentSkillScript>? Scripts { get; }
+
+// Inline script wraps an AIFunction internally
+var script = new AgentInlineSkillScript(ConvertUnits, "convert");
+
+// Pre-built AIFunction must be wrapped
+var script = new AgentInlineSkillScript(myAIFunction);
+
+// Class-based skill declares scripts as:
+public override IReadOnlyList<AgentSkillScript>? Scripts { get; } =
+[
+    new AgentInlineSkillScript(ConvertUnits, "convert"),
+];
+
+// Provider executes scripts by passing the owning skill:
+await script.RunAsync(skill, arguments, cancellationToken);
+```
+
+**Pros:**
+
+- **Explicit skill context at execution time.** `RunAsync` receives the owning `AgentSkill`, so any script can access skill metadata or resources during execution without requiring construction-time wiring.
+- **Self-contained abstraction.** A dedicated type communicates clearly that scripts are a skills-framework concept, separate from general-purpose AI functions.
+- **Easier extensibility for custom script types.** Third-party implementations can subclass `AgentSkillScript` and access the owning skill in `RunAsync` without special setup.
+
+**Cons:**
+
+- **Wrapper overhead.** `AgentInlineSkillScript` is a thin pass-through around `AIFunction` — it adds a class, a constructor, and an indirection layer for no behavioral difference.
+- **Parallel abstraction.** `AgentSkillScript` and `AIFunction` serve overlapping purposes (named callable with arguments), creating two parallel hierarchies for the same concept.
+- **Friction for consumers.** Users who already have `AIFunction` instances must wrap them in `AgentInlineSkillScript` to use them as scripts, adding ceremony.
+
+### Option B — Reuse `AIFunction` directly
+
+Scripts are represented as `AIFunction` (from `Microsoft.Extensions.AI`). `AgentSkill.Scripts` returns
+`IReadOnlyList<AIFunction>?`. `AgentInlineSkillScript` is eliminated entirely — callers use
+`AIFunctionFactory.Create(delegate, name: ...)` or pass `AIFunction` instances directly.
+`AgentFileSkillScript` becomes an `AIFunction` subclass that captures its owning `AgentFileSkill` via
+an internal back-reference set during construction.
+
+```csharp
+// AgentSkill exposes scripts as AIFunction directly:
+public abstract IReadOnlyList<AIFunction>? Scripts { get; }
+
+// Inline scripts use AIFunctionFactory — no wrapper class needed
+var skill = new AgentInlineSkill("my-skill", "desc", "instructions");
+skill.AddScript(ConvertUnits, "convert");           // delegate
+skill.AddScript(myAIFunction);                       // pre-built AIFunction — no wrapping
+
+// Class-based skill declares scripts as:
+public override IReadOnlyList<AIFunction>? Scripts { get; } =
+[
+    AIFunctionFactory.Create(ConvertUnits, name: "convert"),
+];
+
+// Provider executes scripts via standard AIFunction invocation:
+await script.InvokeAsync(arguments, cancellationToken);
+
+// File-based scripts extend AIFunction and capture the owning skill internally:
+public sealed class AgentFileSkillScript : AIFunction
+{
+    internal AgentFileSkill? Skill { get; set; }   // set by AgentFileSkill constructor
+
+    protected override async ValueTask<object?> InvokeCoreAsync(
+        AIFunctionArguments arguments, CancellationToken cancellationToken)
+    {
+        return await _executor(Skill!, this, arguments, cancellationToken);
+    }
+}
+```
+
+**Pros:**
+
+- **Fewer types.** Eliminates `AgentSkillScript` and `AgentInlineSkillScript`, reducing the public API surface by two classes.
+- **Seamless interop.** Any `AIFunction` — whether from `AIFunctionFactory`, a custom subclass, or an external library — can be used as a skill script with zero wrapping.
+- **Consistent with `Microsoft.Extensions.AI` ecosystem.** Scripts share the same type as tool functions used by `IChatClient` and `FunctionInvokingChatClient`, reducing conceptual overhead for developers already familiar with the ecosystem.
+
+**Cons:**
+
+- **No owning-skill context in invocation signature.** `AIFunction.InvokeAsync` does not accept an `AgentSkill` parameter, so `AgentFileSkillScript` must capture its owning skill via an internal setter during construction. This adds a construction-order dependency: the skill must set the back-reference on its scripts.
+- **Custom script types lose automatic skill access.** Third-party `AIFunction` subclasses that need the owning skill must implement their own mechanism (e.g., constructor injection, closure capture) instead of receiving it as a method parameter.
+- **Semantic overloading.** `AIFunction` now means both "a tool the model can call" and "a script within a skill", which could blur the distinction for framework users.
+
+## Resource Representation: `AgentSkillResource` vs `AIFunction`
+
+Two approaches were considered for representing skill resources (supplementary content such as references, assets, or dynamic data):
+
+### Option A — Custom `AgentSkillResource` abstract base class (original design)
+
+Resources are modeled as a custom `AgentSkillResource` abstract class with `Name`, `Description`, and
+`ReadAsync(IServiceProvider?, CancellationToken)`. Concrete implementations:
+`AgentInlineSkillResource` (static value, delegate, or `AIFunction` wrapper) and `AgentFileSkillResource` (reads file content from disk).
+
+```csharp
+// Base type
+public abstract class AgentSkillResource
+{
+    public string Name { get; }
+    public string? Description { get; }
+    public abstract Task<object?> ReadAsync(IServiceProvider? serviceProvider = null, CancellationToken cancellationToken = default);
+}
+
+// AgentSkill exposes resources as:
+public abstract IReadOnlyList<AgentSkillResource>? Resources { get; }
+
+// Static resource
+var resource = new AgentInlineSkillResource("static content", "my-resource");
+
+// Dynamic resource (delegate)
+var resource = new AgentInlineSkillResource((IServiceProvider sp) => GetData(sp), "my-resource");
+
+// Pre-built AIFunction must be wrapped
+var resource = new AgentInlineSkillResource(myAIFunction);
+
+// Class-based skill declares resources as:
+public override IReadOnlyList<AgentSkillResource>? Resources { get; } =
+[
+    new AgentInlineSkillResource("# Conversion Tables\n...", "conversion-table"),
+];
+
+// Provider reads resources via:
+await resource.ReadAsync(serviceProvider, cancellationToken);
+```
+
+**Pros:**
+
+- **Clear semantic distinction.** A dedicated `AgentSkillResource` type distinguishes resources (data providers) from scripts (executable actions), making the API self-documenting.
+- **Purpose-built API.** `ReadAsync` communicates intent better than `InvokeAsync` for a data-access operation.
+
+**Cons:**
+
+- **Wrapper overhead.** `AgentInlineSkillResource` wraps `AIFunction` internally for delegate/function cases — adding a class and indirection for no behavioral difference.
+- **Parallel abstraction.** `AgentSkillResource` and `AIFunction` serve overlapping purposes (named callable that returns data), creating two parallel hierarchies.
+- **Friction for consumers.** Users who already have `AIFunction` instances must wrap them in `AgentInlineSkillResource`, adding ceremony.
+
+### Option B — Reuse `AIFunction` directly
+
+Resources are represented as `AIFunction`. `AgentSkill.Resources` returns `IReadOnlyList<AIFunction>?`.
+`AgentInlineSkillResource` becomes an `AIFunction` subclass (retained as a convenience for the static-value
+pattern: `new AgentInlineSkillResource("data", "name")`). `AgentFileSkillResource` becomes an `AIFunction`
+subclass that reads file content.
+
+```csharp
+// AgentSkill exposes resources as AIFunction directly:
+public abstract IReadOnlyList<AIFunction>? Resources { get; }
+
+// Static resource — AgentInlineSkillResource is retained as a convenience AIFunction subclass
+var resource = new AgentInlineSkillResource("static content", "my-resource");
+
+// Dynamic resource — AgentInlineSkillResource wraps delegate as AIFunction
+var resource = new AgentInlineSkillResource((IServiceProvider sp) => GetData(sp), "my-resource");
+
+// Pre-built AIFunction can be used directly — no wrapping needed
+skill.AddResource(myAIFunction);
+
+// Class-based skill declares resources as:
+public override IReadOnlyList<AIFunction>? Resources { get; } =
+[
+    new AgentInlineSkillResource("# Conversion Tables\n...", "conversion-table"),
+];
+
+// Provider reads resources via standard AIFunction invocation:
+await resource.InvokeAsync(arguments, cancellationToken);
+
+// File-based resources extend AIFunction directly:
+internal sealed class AgentFileSkillResource : AIFunction
+{
+    public string FullPath { get; }
+
+    protected override async ValueTask<object?> InvokeCoreAsync(
+        AIFunctionArguments arguments, CancellationToken cancellationToken)
+    {
+        return await File.ReadAllTextAsync(FullPath, Encoding.UTF8, cancellationToken);
+    }
+}
+```
+
+**Pros:**
+
+- **Fewer base types.** Eliminates the `AgentSkillResource` abstract class, reducing the public API surface.
+- **Seamless interop.** Any `AIFunction` can be used as a skill resource with zero wrapping.
+
+**Cons:**
+
+- **Loss of semantic distinction.** Resources and scripts are now both `AIFunction`, which could make it less obvious which list a function belongs to when reading code.
+- **Static values require a wrapper.** Unlike the original `ReadAsync` which could return a stored value directly, `AIFunction.InvokeAsync` implies invocation. `AgentInlineSkillResource` is retained as a convenience subclass to handle the static-value case, so this is not eliminated — just moved to a different class.
+
+## Decision Outcome
+
+### 1. Keep `AgentSkillResource` and `AgentSkillScript` (Option A for both sections)
+
+We are staying with the custom `AgentSkillResource` and `AgentSkillScript` model classes instead of reusing `AIFunction`:
+
+- **Resources have no parameters.** If a consumer provides an `AIFunction` with parameters, those parameters will never be advertised to the LLM, and the resulting call will fail.
+- **Approval breaks for `AIFunction`-based representations.** When a resource or script represented by an `AIFunction` is configured with approval, the second approval invocation will not work correctly.
+- **Injecting the owning skill into an `AIFunction`-based script is problematic.** Constructor injection would introduce a circular reference between the skill and the script. An internal property setter is possible but adds coupling.
+
+### 2. Make all agent skill classes internal
+
+All agent-skill-related classes are made `internal` to minimize the public API surface while the feature matures. We can reconsider and promote types to `public` later based on community signal.
+
+This leaves two public entry points:
+
+- **`AgentSkillsProvider`** — use directly when all skills come from a single source and filtering is not needed.
+- **`AgentSkillsProviderBuilder`** — use when mixing skill types or when filtering support is required.
+
+### 3. Caching at provider level
+
+Caching of tools and instructions is implemented inside `AgentSkillsProvider` rather than as an external decorator. Recreating tools and instructions on every provider call is wasteful, and a caching decorator sitting outside the provider would not have the information needed to cache them effectively.
@@ -0,0 +1,116 @@
+---
+status: accepted
+contact: westey-m
+date: 2026-03-23
+deciders: sergeymenshykh, markwallace, rbarreto, dmytrostruk, westey-m, eavanvalkenburg, stephentoub
+consulted:
+informed:
+---
+
+# Chat History Persistence Consistency
+
+## Context and Problem Statement
+
+When using `ChatClientAgent` with tools, the `FunctionInvokingChatClient` (FIC) loops multiple times — service call → tool execution → service call → … — before producing a final response. There are two points of discrepancy between how chat history is stored by the framework's `ChatHistoryProvider` and how the underlying AI service stores chat history (e.g., OpenAI Responses with `store=true`):
+
+1. **Persistence timing**: The AI service persists messages after *each* service call within the FIC loop. The `ChatHistoryProvider` currently persists messages only once, at the *end* of the full agent run (after all FIC loop iterations complete).
+
+2. **Trailing `FunctionResultContent` storage**: When tool calling is terminated mid-loop (e.g., via `FunctionInvokingChatClient` termination filters), the final response from the agent may contain `FunctionResultContent` that was never sent to a subsequent service call. The AI service never stores this trailing `FunctionResultContent`, but the `ChatHistoryProvider` currently stores all response content, including the trailing `FunctionResultContent`.
+
+These discrepancies mean that a `ChatHistoryProvider`-managed conversation and a service-managed conversation can diverge in content and structure, even when processing the same interactions.
+
+### Practical Impact: Resuming After Tool-Call Termination
+
+Today, users of `AIAgent` get different behaviors depending on whether chat history is stored service-side or in a `ChatHistoryProvider`. This creates concrete challenges — for example, when the function call loop is terminated and the user wants to resume the conversation in a subsequent run. With service-stored history, the trailing `FunctionResultContent` is never persisted, so the last stored message is the `FunctionCallContent` from the service. With `ChatHistoryProvider`-stored history, the trailing `FunctionResultContent` *is* persisted. The user cannot know whether the last `FunctionResultContent` is in the chat history or not without inspecting the storage mechanism, making it difficult to write resumption logic that works correctly regardless of the storage backend.
+
+### Relationship Between the Two Discrepancies
+
+The persistence timing and `FunctionResultContent` trimming behaviors are interrelated:
+
+- **Per-service-call persistence**: When messages are persisted after each individual service call, trailing `FunctionResultContent` trimming is unnecessary. If tool calling is terminated, the `FunctionResultContent` from the terminated call was never sent to a subsequent service call, so it is never persisted. The per-service-call approach naturally matches the service's behavior.
+
+- **Per-run persistence**: When messages are batched and persisted at the end of the full run, trailing `FunctionResultContent` trimming becomes necessary to match the service's behavior. Without trimming, the stored history contains `FunctionResultContent` that the service would never have stored.
+
+This means the trimming feature (introduced in [PR #4792](https://github.com/microsoft/agent-framework/pull/4792)) is primarily needed as a complement to per-run persistence. The `PersistChatHistoryAtEndOfRun` setting (introduced in [PR #4762](https://github.com/microsoft/agent-framework/pull/4762)) inverts the default so that per-service-call persistence is the standard behavior, and per-run persistence is opt-in.
+
+## Decision Drivers
+
+- **A. Consistency**: The default behavior of `ChatHistoryProvider` should produce stored history that closely matches what the underlying AI service would store, minimizing surprise when switching between framework-managed and service-managed chat history.
+- **B. Atomicity**: A run that fails mid-way through a multi-step tool-calling loop should not leave chat history in a partially-updated state, unless the user explicitly opts into that behavior.
+- **C. Recoverability**: For long-running tool-calling loops, it should be possible to recover intermediate progress if the process is interrupted, rather than losing all work from the current run.
+- **D. Simplicity**: The default behavior should be easy to understand and predict for most users, without requiring knowledge of the FIC loop internals.
+- **E. Flexibility**: Regardless of the chosen default, users should be able to opt into the alternative behavior.
+
+## Considered Options
+
+- Option 1: Default to per-run persistence with `FunctionResultContent` trimming (opt-in to per-service-call)
+- Option 2: Default to per-service-call persistence (opt-in to per-run)
+
+## Pros and Cons of the Options
+
+### Option 1: Default to per-run persistence with `FunctionResultContent` trimming
+
+Keep the current default behavior of persisting chat history only at the end of the full agent run. Add `FunctionResultContent` trimming as the default to improve consistency with service storage. Provide an opt-in setting for users who want per-service-call persistence.
+
+Settings:
+- `PersistChatHistoryAtEndOfRun` = `true`
+
+- Good, because runs are atomic — chat history is only updated when the full run succeeds, satisfying driver B.
+- Good, because the mental model is simple: one run = one history update, satisfying driver D.
+- Good, because trimming trailing `FunctionResultContent` improves consistency with service storage, partially satisfying driver A.
+- Good, because users can opt in to per-service-call persistence for checkpointing/recovery scenarios, satisfying drivers C and E.
+- Bad, because the default persistence timing still differs from the service's behavior (per-run vs. per-service-call), only partially satisfying driver A.
+- Bad, because if the process crashes mid-loop, all intermediate progress from the current run is lost, not satisfying driver C by default.
+
+### Option 2: Default to per-service-call persistence
+
+Change the default to persist chat history after each individual service call within the FIC loop, matching the AI service's behavior. Trailing `FunctionResultContent` trimming is unnecessary with this approach (it is naturally handled). Provide an opt-in setting for users who want per-run atomicity with trimming.
+
+Settings:
+- `PersistChatHistoryAtEndOfRun` = `false` (default)
+
+- Good, because the stored history matches the service's behavior by default for both timing and content, fully satisfying driver A.
+- Good, because intermediate progress is preserved if the process is interrupted, satisfying driver C.
+- Good, because no separate `FunctionResultContent` trimming logic is needed, reducing complexity.
+- Bad, because chat history may be left in an incomplete state if the run fails mid-loop (e.g., `FunctionCallContent` stored without corresponding `FunctionResultContent`), not satisfying driver B. A subsequent run cannot proceed without manually providing the missing `FunctionResultContent`.
+- Bad, because the mental model is more complex: a single run may produce multiple history updates, partially failing driver D.
+- Neutral, because users can opt out to per-run persistence if they prefer atomicity, satisfying driver E.
+
+## Decision Outcome
+
+Chosen option: **Option 2 — Default to per-service-call persistence**, because it fully satisfies the consistency driver (A), naturally handles `FunctionResultContent` trimming without additional logic, and provides better recoverability for long-running tool-calling loops. Per-run persistence remains available via the `PersistChatHistoryAtEndOfRun` setting for users who prefer atomic run semantics.
+
+### Configuration Matrix
+
+The behavior depends on the combination of `UseProvidedChatClientAsIs` and `PersistChatHistoryAtEndOfRun`:
+
+| `UseProvidedChatClientAsIs` | `PersistChatHistoryAtEndOfRun` | Behavior |
+|---|---|---|
+| `false` (default) | `false` (default) | **Per-service-call persistence.** A `ChatHistoryPersistingChatClient` middleware is automatically injected into the chat client pipeline between `FunctionInvokingChatClient` and the leaf `IChatClient`. Messages are persisted after each service call. |
+| `true` | `false` | **User responsibility.** No middleware is injected because the user has provided a custom chat client stack. The user is responsible for ensuring correct persistence behavior (e.g., by including their own persisting middleware). |
+| `false` | `true` | **Per-run persistence with marking.** A `ChatHistoryPersistingChatClient` middleware is injected, but configured to *mark* messages with metadata rather than store them immediately. At the end of the run, marked messages are stored. Trailing `FunctionResultContent` is trimmed. |
+| `true` | `true` | **Per-run persistence with warning.** The system checks whether the custom chat client stack includes a `ChatHistoryPersistingChatClient`. If not, a warning is emitted (particularly relevant for workflow handoff scenarios where trimming cannot be guaranteed). If no `ChatHistoryPersistingChatClient` is preset, all messages are stored at the end of the run, otherwise marked messages are stored. |
+
+### Consequences
+
+- Good, because the stored history matches the service's behavior by default for both timing and content, fully satisfying consistency (driver A).
+- Good, because intermediate progress is preserved if the process is interrupted, satisfying recoverability (driver C).
+- Good, because no separate `FunctionResultContent` trimming logic is needed in the default path, reducing complexity.
+- Good, because marking persisted messages with metadata enables deduplication and aids debugging.
+- Good, because warnings for custom chat client configurations without the persisting middleware help prevent silent failures in workflow handoff scenarios.
+- Bad, because chat history may be left in an incomplete state if the run fails mid-loop (e.g., `FunctionCallContent` stored without corresponding `FunctionResultContent`), requiring manual recovery in rare cases.
+- Bad, because the mental model is more complex for the default path: a single run may produce multiple history updates.
+- Neutral, because users who prefer atomic run semantics can opt in to per-run persistence via `PersistChatHistoryAtEndOfRun = true`.
+- Neutral, because increased write frequency from per-service-call persistence may impact performance for some storage backends; this can be mitigated with a caching decorator.
+
+### Implementation Notes
+
+#### Conversation ID Consistency
+
+The `ChatHistoryPersistingChatClient` middleware must also update the session's `ConversationId` consistently for both response-based and conversation-based service interactions, ensuring the session always reflects the latest service-provided identifier.
+
+## More Information
+
+- [PR #4762: Persist messages during function call loop](https://github.com/microsoft/agent-framework/pull/4762) — introduces `PersistChatHistoryAfterEachServiceCall` option and `ChatHistoryPersistingChatClient` decorator
+- [PR #4792: Trim final FRC to match service storage](https://github.com/microsoft/agent-framework/pull/4792) — introduces `StoreFinalFunctionResultContent` option and `FilterFinalFunctionResultContent` logic
+- [Issue #2889](https://github.com/microsoft/agent-framework/issues/2889) — original issue tracking chat history persistence during function call loops
@@ -77,6 +77,8 @@
    <Project Path="samples/04-hosting/DurableWorkflows/AzureFunctions/01_SequentialWorkflow/01_SequentialWorkflow.csproj" />
    <Project Path="samples/04-hosting/DurableWorkflows/AzureFunctions/02_ConcurrentWorkflow/02_ConcurrentWorkflow.csproj" />
    <Project Path="samples/04-hosting/DurableWorkflows/AzureFunctions/03_WorkflowHITL/03_WorkflowHITL.csproj" />
+    <Project Path="samples/04-hosting/DurableWorkflows/AzureFunctions/04_WorkflowMcpTool/04_WorkflowMcpTool.csproj" />
+    <Project Path="samples/04-hosting/DurableWorkflows/AzureFunctions/05_WorkflowAndAgents/05_WorkflowAndAgents.csproj" />
  </Folder>
  <Folder Name="/Samples/GettingStarted/">
    <File Path="samples/GettingStarted/README.md" />
@@ -102,7 +104,7 @@
  </Folder>
  <Folder Name="/Samples/02-agents/AgentSkills/">
    <File Path="samples/02-agents/AgentSkills/README.md" />
-    <Project Path="samples/02-agents/AgentSkills/Agent_Step01_BasicSkills/Agent_Step01_BasicSkills.csproj" />
+    <Project Path="samples/02-agents/AgentSkills/Agent_Step01_FileBasedSkills/Agent_Step01_FileBasedSkills.csproj" />
  </Folder>
  <Folder Name="/Samples/02-agents/AGUI/Step05_StateManagement/">
    <Project Path="samples/02-agents/AGUI/Step05_StateManagement/Client/Client.csproj" />
@@ -18,6 +18,7 @@ using OpenTelemetry.Trace;

 #region Setup Telemetry

+// Source name for this sample's custom ActivitySource and Meter; other instrumentation uses their own sources/categories.
 const string SourceName = "OpenTelemetryAspire.ConsoleApp";
 const string ServiceName = "AgentOpenTelemetry";

@@ -40,7 +41,6 @@ var resource = ResourceBuilder.CreateDefault()
 var tracerProviderBuilder = Sdk.CreateTracerProviderBuilder()
    .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(ServiceName, serviceVersion: "1.0.0"))
    .AddSource(SourceName) // Our custom activity source
-    .AddSource("*Microsoft.Agents.AI") // Agent Framework telemetry
    .AddHttpClientInstrumentation() // Capture HTTP calls to OpenAI
    .AddOtlpExporter(options => options.Endpoint = new Uri(otlpEndpoint));

@@ -54,8 +54,7 @@ using var tracerProvider = tracerProviderBuilder.Build();
 // Setup metrics with resource and instrument name filtering
 using var meterProvider = Sdk.CreateMeterProviderBuilder()
    .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(ServiceName, serviceVersion: "1.0.0"))
-    .AddMeter(SourceName) // Our custom meter
-    .AddMeter("*Microsoft.Agents.AI") // Agent Framework metrics
+    .AddMeter(SourceName) // Our custom meter source
    .AddHttpClientInstrumentation() // HTTP client metrics
    .AddRuntimeInstrumentation() // .NET runtime metrics
    .AddOtlpExporter(options => options.Endpoint = new Uri(otlpEndpoint))
@@ -128,7 +127,7 @@ var agent = new ChatClientAgent(instrumentedChatClient,
    instructions: "You are a helpful assistant that provides concise and informative responses.",
    tools: [AIFunctionFactory.Create(GetWeatherAsync)])
    .AsBuilder()
-    .UseOpenTelemetry(SourceName, configure: (cfg) => cfg.EnableSensitiveData = true) // enable telemetry at the agent level
+    .UseOpenTelemetry(sourceName: SourceName, configure: (cfg) => cfg.EnableSensitiveData = true) // enable telemetry at the agent level
    .Build();

 var session = await agent.CreateSessionAsync();
@@ -1,50 +0,0 @@
-// Copyright (c) Microsoft. All rights reserved.
-
-// This sample demonstrates how to use Agent Skills with a ChatClientAgent.
-// Agent Skills are modular packages of instructions and resources that extend an agent's capabilities.
-// Skills follow the progressive disclosure pattern: advertise -> load -> read resources.
-//
-// This sample includes the expense-report skill:
-//   - Policy-based expense filing with references and assets
-
-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";
-
-// --- Skills Provider ---
-// Discovers skills from the 'skills' directory and makes them available to the agent
-var skillsProvider = new FileAgentSkillsProvider(skillPath: Path.Combine(AppContext.BaseDirectory, "skills"));
-
-// --- Agent Setup ---
-AIAgent agent = new AzureOpenAIClient(new Uri(endpoint), new DefaultAzureCredential())
-    .GetResponsesClient()
-    .AsAIAgent(new ChatClientAgentOptions
-    {
-        Name = "SkillsAgent",
-        ChatOptions = new()
-        {
-            Instructions = "You are a helpful assistant.",
-        },
-        AIContextProviders = [skillsProvider],
-    },
-    model: deploymentName);
-
-// --- Example 1: Expense policy question (loads FAQ resource) ---
-Console.WriteLine("Example 1: Checking expense policy FAQ");
-Console.WriteLine("---------------------------------------");
-AgentResponse response1 = await agent.RunAsync("Are tips reimbursable? I left a 25% tip on a taxi ride and want to know if that's covered.");
-Console.WriteLine($"Agent: {response1.Text}\n");
-
-// --- Example 2: Filing an expense report (multi-turn with template asset) ---
-Console.WriteLine("Example 2: Filing an expense report");
-Console.WriteLine("---------------------------------------");
-AgentSession session = await agent.CreateSessionAsync();
-AgentResponse response2 = await agent.RunAsync("I had 3 client dinners and a $1,200 flight last week. Return a draft expense report and ask about any missing details.",
-    session);
-Console.WriteLine($"Agent: {response2.Text}\n");
@@ -1,63 +0,0 @@
-# Agent Skills Sample
-
-This sample demonstrates how to use **Agent Skills** with a `ChatClientAgent` in the Microsoft Agent Framework.
-
-## What are Agent Skills?
-
-Agent Skills are modular packages of instructions and resources that enable AI agents to perform specialized tasks. They follow the [Agent Skills specification](https://agentskills.io/) and implement the progressive disclosure pattern:
-
-1. **Advertise**: Skills are advertised with name + description (~100 tokens per skill)
-2. **Load**: Full instructions are loaded on-demand via `load_skill` tool
-3. **Resources**: References and other files loaded via `read_skill_resource` tool
-
-## Skills Included
-
-### expense-report
-Policy-based expense filing with spending limits, receipt requirements, and approval workflows.
- `references/POLICY_FAQ.md` — Detailed expense policy Q&A
- `assets/expense-report-template.md` — Submission template
-
-## Project Structure
-
-```
-Agent_Step01_BasicSkills/
-├── Program.cs
-├── Agent_Step01_BasicSkills.csproj
-└── skills/
-    └── expense-report/
-        ├── SKILL.md
-        ├── references/
-        │   └── POLICY_FAQ.md
-        └── assets/
-            └── expense-report-template.md
-```
-
-## Running the Sample
-
-### Prerequisites
- .NET 10.0 SDK
- Azure OpenAI endpoint with a deployed model
-
-### Setup
-1. Set environment variables:
-   ```bash
-   export AZURE_OPENAI_ENDPOINT="https://your-endpoint.openai.azure.com/"
-   export AZURE_OPENAI_DEPLOYMENT_NAME="gpt-4o-mini"
-   ```
-
-2. Run the sample:
-   ```bash
-   dotnet run
-   ```
-
-### Examples
-
-The sample runs two examples:
-
-1. **Expense policy FAQ** — Asks about tip reimbursement; the agent loads the expense-report skill and reads the FAQ resource
-2. **Filing an expense report** — Multi-turn conversation to draft an expense report using the template asset
-
-## Learn More
-
- [Agent Skills Specification](https://agentskills.io/)
- [Microsoft Agent Framework Documentation](../../../../../docs/)
@@ -1,40 +0,0 @@
---
-name: expense-report
-description: File and validate employee expense reports according to Contoso company policy. Use when asked about expense submissions, reimbursement rules, receipt requirements, spending limits, or expense categories.
-metadata:
-  author: contoso-finance
-  version: "2.1"
---
-
-# Expense Report
-
-## Categories and Limits
-
-| Category | Limit | Receipt | Approval |
-|---|---|---|---|
-| Meals — solo | $50/day | >$25 | No |
-| Meals — team/client | $75/person | Always | Manager if >$200 total |
-| Lodging | $250/night | Always | Manager if >3 nights |
-| Ground transport | $100/day | >$15 | No |
-| Airfare | Economy | Always | Manager; VP if >$1,500 |
-| Conference/training | $2,000/event | Always | Manager + L&D |
-| Office supplies | $100 | Yes | No |
-| Software/subscriptions | $50/month | Yes | Manager if >$200/year |
-
-## Filing Process
-
-1. Collect receipts — must show vendor, date, amount, payment method.
-2. Categorize per table above.
-3. Use template: [assets/expense-report-template.md](assets/expense-report-template.md).
-4. For client/team meals: list attendee names and business purpose.
-5. Submit — auto-approved if <$500; manager if $500–$2,000; VP if >$2,000.
-6. Reimbursement: 10 business days via direct deposit.
-
-## Policy Rules
-
- Submit within 30 days of transaction.
- Alcohol is never reimbursable.
- Foreign currency: convert to USD at transaction-date rate; note original currency and amount.
- Mixed personal/business travel: only business portion reimbursable; provide comparison quotes.
- Lost receipts (>$25): file Lost Receipt Affidavit from Finance. Max 2 per quarter.
- For policy questions not covered above, consult the FAQ: [references/POLICY_FAQ.md](references/POLICY_FAQ.md). Answers should be based on what this document and the FAQ state.
@@ -1,5 +0,0 @@
-# Expense Report Template
-
-| Date | Category | Vendor | Description | Amount (USD) | Original Currency | Original Amount | Attendees | Business Purpose | Receipt Attached |
-|------|----------|--------|-------------|--------------|-------------------|-----------------|-----------|------------------|------------------|
-|      |          |        |             |              |                   |                 |           |                  | Yes or No        |
@@ -1,55 +0,0 @@
-# Expense Policy — Frequently Asked Questions
-
-## Meals
-
-**Q: Can I expense coffee or snacks during the workday?**
-A: Daily coffee/snacks under $10 are not reimbursable (considered personal). Coffee purchased during a client meeting or team working session is reimbursable as a team meal.
-
-**Q: What if a team dinner exceeds the per-person limit?**
-A: The $75/person limit applies as a guideline. Overages up to 20% are accepted with a written justification (e.g., "client dinner at venue chosen by client"). Overages beyond 20% require pre-approval from your VP.
-
-**Q: Do I need to list every attendee?**
-A: Yes. For client meals, list the client's name and company. For team meals, list all employee names. For groups over 10, you may attach a separate attendee list.
-
-## Travel
-
-**Q: Can I book a premium economy or business class flight?**
-A: Economy class is the standard. Premium economy is allowed for flights over 6 hours. Business class requires VP pre-approval and is generally reserved for flights over 10 hours or medical accommodation.
-
-**Q: What about ride-sharing (Uber/Lyft) vs. rental cars?**
-A: Use ride-sharing for trips under 30 miles round-trip. Rent a car for multi-day travel or when ride-sharing would exceed $100/day. Always choose the compact/standard category unless traveling with 3+ people.
-
-**Q: Are tips reimbursable?**
-A: Tips up to 20% are reimbursable for meals, taxi/ride-share, and hotel housekeeping. Tips above 20% require justification.
-
-## Lodging
-
-**Q: What if the $250/night limit isn't enough for the city I'm visiting?**
-A: For high-cost cities (New York, San Francisco, London, Tokyo, Sydney), the limit is automatically increased to $350/night. No additional approval is needed. For other locations where rates are unusually high (e.g., during a major conference), request a per-trip exception from your manager before booking.
-
-**Q: Can I stay with friends/family instead and get a per-diem?**
-A: No. Contoso reimburses actual lodging costs only, not per-diems.
-
-## Subscriptions and Software
-
-**Q: Can I expense a personal productivity tool?**
-A: Software must be directly related to your job function. Tools like IDE licenses, design software, or project management apps are reimbursable. General productivity apps (note-taking, personal calendar) are not, unless your manager confirms a business need in writing.
-
-**Q: What about annual subscriptions?**
-A: Annual subscriptions over $200 require manager approval before purchase. Submit the approval email with your expense report.
-
-## Receipts and Documentation
-
-**Q: My receipt is faded/damaged. What do I do?**
-A: Try to obtain a duplicate from the vendor. If not possible, submit a Lost Receipt Affidavit (available from the Finance SharePoint site). You're limited to 2 affidavits per quarter.
-
-**Q: Do I need a receipt for parking meters or tolls?**
-A: For amounts under $15, no receipt is required — just note the date, location, and amount. For $15 and above, a receipt or bank/credit card statement excerpt is required.
-
-## Approval and Reimbursement
-
-**Q: My manager is on leave. Who approves my report?**
-A: Expense reports can be approved by your skip-level manager or any manager designated as an alternate approver in the expense system.
-
-**Q: Can I submit expenses from a previous quarter?**
-A: The standard 30-day window applies. Expenses older than 30 days require a written explanation and VP approval. Expenses older than 90 days are not reimbursable except in extraordinary circumstances (extended leave, medical emergency) with CFO approval.
@@ -14,6 +14,10 @@
    <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>
@@ -0,0 +1,48 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// This sample demonstrates how to use file-based Agent Skills with a ChatClientAgent.
+// Skills are discovered from SKILL.md files on disk and follow the progressive disclosure pattern:
+// 1. Advertise — skill names and descriptions in the system prompt
+// 2. Load — full instructions loaded on demand via load_skill tool
+// 3. Read resources — reference files read via read_skill_resource tool
+// 4. Run scripts — scripts executed via run_skill_script tool with a subprocess executor
+//
+// This sample uses a unit-converter skill that converts between miles, kilometers, pounds, and kilograms.
+
+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";
+
+// --- Skills Provider ---
+// Discovers skills from the 'skills' directory containing SKILL.md files.
+// The script runner runs file-based scripts (e.g. Python) as local subprocesses.
+var skillsProvider = new AgentSkillsProvider(
+    Path.Combine(AppContext.BaseDirectory, "skills"),
+    SubprocessScriptRunner.RunAsync);
+// --- 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 file-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}");
@@ -0,0 +1,51 @@
+# File-Based Agent Skills Sample
+
+This sample demonstrates how to use **file-based Agent Skills** with a `ChatClientAgent`.
+
+## What it demonstrates
+
+- 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
+- Running file-based scripts (Python) via a subprocess-based executor
+
+## Skills Included
+
+### unit-converter
+
+Converts between common units (miles↔km, pounds↔kg) using a multiplication factor.
+
+- `references/conversion-table.md` — Conversion factor table
+- `scripts/convert.py` — Python script that performs the conversion
+
+## Running the Sample
+
+### Prerequisites
+
+- .NET 10.0 SDK
+- Azure OpenAI endpoint with a deployed model
+- Python 3 installed and available as `python3` on your PATH
+
+### 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 file-based skills
+------------------------------------------------------------
+Agent: Here are your conversions:
+
+1. **26.2 miles → 42.16 km** (a marathon distance)
+2. **75 kg → 165.35 lbs**
+```
@@ -0,0 +1,11 @@
+---
+name: unit-converter
+description: Convert between common units using a multiplication factor. Use when asked to convert miles, kilometers, pounds, or kilograms.
+---
+
+## Usage
+
+When the user requests a unit conversion:
+1. First, review `references/conversion-table.md` to find the correct factor
+2. Run the `scripts/convert.py` script with `--value <number> --factor <factor>` (e.g. `--value 26.2 --factor 1.60934`)
+3. Present the converted value clearly with both units
@@ -0,0 +1,10 @@
+# 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  |
@@ -0,0 +1,29 @@
+# Unit conversion script
+# Converts a value using a multiplication factor: result = value × factor
+#
+# Usage:
+#   python scripts/convert.py --value 26.2 --factor 1.60934
+#   python scripts/convert.py --value 75 --factor 2.20462
+
+import argparse
+import json
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(
+        description="Convert a value using a multiplication factor.",
+        epilog="Examples:\n"
+        "  python scripts/convert.py --value 26.2 --factor 1.60934\n"
+        "  python scripts/convert.py --value 75 --factor 2.20462",
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    parser.add_argument("--value", type=float, required=True, help="The numeric value to convert.")
+    parser.add_argument("--factor", type=float, required=True, help="The conversion factor from the table.")
+    args = parser.parse_args()
+
+    result = round(args.value * args.factor, 4)
+    print(json.dumps({"value": args.value, "factor": args.factor, "result": result}))
+
+
+if __name__ == "__main__":
+    main()
@@ -4,4 +4,4 @@ Samples demonstrating Agent Skills capabilities.

 | Sample | Description |
 |--------|-------------|
-| [Agent_Step01_BasicSkills](Agent_Step01_BasicSkills/) | Using Agent Skills with a ChatClientAgent, including progressive disclosure and skill resources |
+| [Agent_Step01_FileBasedSkills](Agent_Step01_FileBasedSkills/) | Define skills as `SKILL.md` files on disk with reference documents. Uses a unit-converter skill. |
@@ -0,0 +1,137 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// Sample subprocess-based skill script runner.
+// Executes file-based skill scripts as local subprocesses.
+// This is provided for demonstration purposes only.
+
+using System.Diagnostics;
+using Microsoft.Agents.AI;
+using Microsoft.Extensions.AI;
+
+/// <summary>
+/// Executes file-based skill scripts as local subprocesses.
+/// </summary>
+/// <remarks>
+/// This runner uses the script's absolute path, converts the arguments
+/// to CLI flags, and returns captured output. It is intended for
+/// demonstration purposes only.
+/// </remarks>
+internal static class SubprocessScriptRunner
+{
+    /// <summary>
+    /// Runs a skill script as a local subprocess.
+    /// </summary>
+    public static async Task<object?> RunAsync(
+        AgentFileSkill skill,
+        AgentFileSkillScript script,
+        AIFunctionArguments arguments,
+        CancellationToken cancellationToken)
+    {
+        if (!File.Exists(script.FullPath))
+        {
+            return $"Error: Script file not found: {script.FullPath}";
+        }
+
+        string extension = Path.GetExtension(script.FullPath);
+        string? interpreter = extension switch
+        {
+            ".py" => "python3",
+            ".js" => "node",
+            ".sh" => "bash",
+            ".ps1" => "pwsh",
+            _ => null,
+        };
+
+        var startInfo = new ProcessStartInfo
+        {
+            RedirectStandardOutput = true,
+            RedirectStandardError = true,
+            UseShellExecute = false,
+            CreateNoWindow = true,
+            WorkingDirectory = Path.GetDirectoryName(script.FullPath) ?? ".",
+        };
+
+        if (interpreter is not null)
+        {
+            startInfo.FileName = interpreter;
+            startInfo.ArgumentList.Add(script.FullPath);
+        }
+        else
+        {
+            startInfo.FileName = script.FullPath;
+        }
+
+        if (arguments is not null)
+        {
+            foreach (var (key, value) in arguments)
+            {
+                if (value is bool boolValue)
+                {
+                    if (boolValue)
+                    {
+                        startInfo.ArgumentList.Add(NormalizeKey(key));
+                    }
+                }
+                else if (value is not null)
+                {
+                    startInfo.ArgumentList.Add(NormalizeKey(key));
+                    startInfo.ArgumentList.Add(value.ToString()!);
+                }
+            }
+        }
+
+        Process? process = null;
+        try
+        {
+            process = Process.Start(startInfo);
+            if (process is null)
+            {
+                return $"Error: Failed to start process for script '{script.Name}'.";
+            }
+
+            Task<string> outputTask = process.StandardOutput.ReadToEndAsync(cancellationToken);
+            Task<string> errorTask = process.StandardError.ReadToEndAsync(cancellationToken);
+
+            await process.WaitForExitAsync(cancellationToken).ConfigureAwait(false);
+
+            string output = await outputTask.ConfigureAwait(false);
+            string error = await errorTask.ConfigureAwait(false);
+
+            if (!string.IsNullOrEmpty(error))
+            {
+                output += $"\nStderr:\n{error}";
+            }
+
+            if (process.ExitCode != 0)
+            {
+                output += $"\nScript exited with code {process.ExitCode}";
+            }
+
+            return string.IsNullOrEmpty(output) ? "(no output)" : output.Trim();
+        }
+        catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+        {
+            // Kill the process on cancellation to avoid leaving orphaned subprocesses.
+            process?.Kill(entireProcessTree: true);
+            throw;
+        }
+        catch (OperationCanceledException)
+        {
+            throw;
+        }
+        catch (Exception ex)
+        {
+            return $"Error: Failed to execute script '{script.Name}': {ex.Message}";
+        }
+        finally
+        {
+            process?.Dispose();
+        }
+    }
+
+    /// <summary>
+    /// Normalizes a parameter key to a consistent --flag format.
+    /// Models may return keys with or without leading dashes (e.g., "value" vs "--value").
+    /// </summary>
+    private static string NormalizeKey(string key) => "--" + key.TrimStart('-');
+}
@@ -73,16 +73,28 @@ foreach (ClientResult result in getConversationItemsResults.GetRawPages())
    using JsonDocument getConversationItemsResultAsJson = JsonDocument.Parse(result.GetRawResponse().Content.ToString());
    foreach (JsonElement element in getConversationItemsResultAsJson.RootElement.GetProperty("data").EnumerateArray())
    {
+        // Skip non-message items (e.g. tool calls, reasoning) that lack a "role" property
+        if (!element.TryGetProperty("role"u8, out var roleElement))
+        {
+            continue;
+        }
+
        string messageId = element.GetProperty("id"u8).ToString();
-        string messageRole = element.GetProperty("role"u8).ToString();
+        string messageRole = roleElement.ToString();
        Console.WriteLine($"    Message ID: {messageId}");
        Console.WriteLine($"    Message Role: {messageRole}");

-        foreach (var content in element.GetProperty("content").EnumerateArray())
+        if (element.TryGetProperty("content"u8, out var contentElement))
        {
-            string messageContentText = content.GetProperty("text"u8).ToString();
-            Console.WriteLine($"    Message Text: {messageContentText}");
+            foreach (var content in contentElement.EnumerateArray())
+            {
+                if (content.TryGetProperty("text"u8, out var textElement))
+                {
+                    Console.WriteLine($"    Message Text: {textElement}");
+                }
+            }
        }
+
        Console.WriteLine();
    }
 }
@@ -16,5 +16,11 @@
  <ItemGroup>
    <ProjectReference Include="..\..\..\..\src\Microsoft.Agents.AI.OpenAI\Microsoft.Agents.AI.OpenAI.csproj" />
  </ItemGroup>
+
+  <ItemGroup>
+    <None Update="Assets\walkway.jpg">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
  
 </Project>
@@ -22,7 +22,7 @@ var agent = new AzureOpenAIClient(new Uri(endpoint), new DefaultAzureCredential(

 ChatMessage message = new(ChatRole.User, [
    new TextContent("What do you see in this image?"),
-    new UriContent("https://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/Gfp-wisconsin-madison-the-nature-boardwalk.jpg/2560px-Gfp-wisconsin-madison-the-nature-boardwalk.jpg", "image/jpeg")
+    await DataContent.LoadFromAsync("Assets/walkway.jpg"),
 ]);

 var session = await agent.CreateSessionAsync();
@@ -24,7 +24,7 @@ AIAgent agent = await aiProjectClient.CreateAIAgentAsync(name: VisionName, model

 ChatMessage message = new(ChatRole.User, [
    new TextContent("What do you see in this image?"),
-    await DataContent.LoadFromAsync("assets/walkway.jpg"),
+    await DataContent.LoadFromAsync("Assets/walkway.jpg"),
 ]);

 AgentSession session = await agent.CreateSessionAsync();
@@ -9,7 +9,7 @@ using Microsoft.Extensions.AI;
 namespace WorkflowAsAnAgentSample;

 /// <summary>
-/// This sample introduces the concepts workflows as agents, where a workflow can be
+/// This sample introduces the concept of workflows as agents, where a workflow can be
 /// treated as an <see cref="AIAgent"/>. This allows you to interact with a workflow
 /// as if it were a single agent.
 ///
@@ -18,6 +18,14 @@ namespace WorkflowAsAnAgentSample;
 ///
 /// You will interact with the workflow in an interactive loop, sending messages and receiving
 /// streaming responses from the workflow as if it were an agent who responds in both languages.
+///
+/// This sample also demonstrates <see cref="IResettableExecutor"/>, which is required
+/// for stateful executors that are shared across multiple workflow runs. Each iteration
+/// of the interactive loop triggers a new workflow run against the same workflow instance.
+/// Between runs, the framework automatically calls <see cref="IResettableExecutor.ResetAsync"/>
+/// on shared executors so that accumulated state (e.g., collected messages) is cleared
+/// before the next run begins. See <c>WorkflowFactory.ConcurrentAggregationExecutor</c>
+/// for the implementation.
 /// </summary>
 /// <remarks>
 /// Pre-requisites:
@@ -39,7 +47,10 @@ public static class Program
        var agent = workflow.AsAIAgent("workflow-agent", "Workflow Agent");
        var session = await agent.CreateSessionAsync();

-        // Start an interactive loop to interact with the workflow as if it were an agent
+        // Start an interactive loop to interact with the workflow as if it were an agent.
+        // Each iteration runs the workflow again on the same workflow instance. Between runs,
+        // the framework calls IResettableExecutor.ResetAsync() on shared stateful executors
+        // (like ConcurrentAggregationExecutor) to clear accumulated state from the previous run.
        while (true)
        {
            Console.WriteLine();
@@ -10,6 +10,14 @@ internal static class WorkflowFactory
 {
    /// <summary>
    /// Creates a workflow that uses two language agents to process input concurrently.
+    ///
+    /// In this workflow, the <c>Start</c> <see cref="ChatForwardingExecutor"/> and the
+    /// <see cref="ConcurrentAggregationExecutor"/> are provided as shared instances, meaning
+    /// the same executor objects are reused across multiple workflow runs. The language agents
+    /// (French and English) are created via a factory and instantiated per workflow run.
+    /// Stateful shared executors must implement <see cref="IResettableExecutor"/> so the
+    /// framework can clear their state between runs. Framework-provided executors like
+    /// <see cref="ChatForwardingExecutor"/> already implement this interface.
    /// </summary>
    /// <param name="chatClient">The chat client to use for the agents</param>
    /// <returns>A workflow that processes input using two language agents</returns>
@@ -40,6 +48,16 @@ internal static class WorkflowFactory

    /// <summary>
    /// Executor that aggregates the results from the concurrent agents.
+    ///
+    /// This executor is stateful — it accumulates messages in <see cref="_messages"/>
+    /// as they arrive from each agent. Because it is provided as a shared instance
+    /// (not via a factory), the same object is reused across workflow runs. Implementing
+    /// <see cref="IResettableExecutor"/> allows the framework to call <see cref="ResetAsync"/>
+    /// between runs, clearing accumulated state so each run starts fresh.
+    ///
+    /// Without <see cref="IResettableExecutor"/>, attempting to reuse a workflow containing
+    /// shared executor instances that do not implement this interface would throw an
+    /// <see cref="InvalidOperationException"/>.
    /// </summary>
    [YieldsOutput(typeof(string))]
    private sealed class ConcurrentAggregationExecutor() :
@@ -65,7 +83,11 @@ internal static class WorkflowFactory
            }
        }

-        /// <inheritdoc/>
+        /// <summary>
+        /// Resets the executor state between workflow runs by clearing accumulated messages.
+        /// The framework calls this automatically when a workflow run completes, before the
+        /// workflow can be used for another run.
+        /// </summary>
        public ValueTask ResetAsync()
        {
            this._messages.Clear();
@@ -35,13 +35,15 @@ public static class FunctionTriggers
        int iterationCount = 0;
        while (iterationCount++ < input.MaxReviewAttempts)
        {
+            // NOTE: CustomStatus has a 16 KB UTF-16 limit in Durable Functions.
+            // Only include short metadata here - the full content is passed via activity inputs/outputs.
            context.SetCustomStatus(
                new
                {
                    message = "Requesting human feedback.",
                    approvalTimeoutHours = input.ApprovalTimeoutHours,
                    iterationCount,
-                    content
+                    contentTitle = content.Title,
                });

            // Step 2: Notify user to review the content
@@ -63,7 +65,6 @@ public static class FunctionTriggers
                    {
                        message = $"Human approval timed out after {input.ApprovalTimeoutHours} hour(s). Treating as rejection.",
                        iterationCount,
-                        content
                    });
                throw new TimeoutException($"Human approval timed out after {input.ApprovalTimeoutHours} hour(s).");
            }
@@ -73,7 +74,7 @@ public static class FunctionTriggers
                context.SetCustomStatus(new
                {
                    message = "Content approved by human reviewer. Publishing content...",
-                    content
+                    contentTitle = content.Title,
                });

                // Step 4: Publish the approved content
@@ -83,7 +84,7 @@ public static class FunctionTriggers
                {
                    message = $"Content published successfully at {context.CurrentUtcDateTime:s}",
                    humanFeedback = humanResponse,
-                    content
+                    contentTitle = content.Title,
                });
                return new { content = content.Content };
            }
@@ -92,7 +93,7 @@ public static class FunctionTriggers
            {
                message = "Content rejected by human reviewer. Incorporating feedback and regenerating...",
                humanFeedback = humanResponse,
-                content
+                contentTitle = content.Title,
            });

            // Incorporate human feedback and regenerate
@@ -77,13 +77,15 @@ static async Task<object> RunOrchestratorAsync(TaskOrchestrationContext context,
    int iterationCount = 0;
    while (iterationCount++ < input.MaxReviewAttempts)
    {
+        // NOTE: CustomStatus has a 16 KB UTF-16 limit in Durable Functions.
+        // Only include short metadata here - the full content is passed via activity inputs/outputs.
        context.SetCustomStatus(
            new
            {
                message = "Requesting human feedback.",
                approvalTimeoutHours = input.ApprovalTimeoutHours,
                iterationCount,
-                content
+                contentTitle = content.Title,
            });

        // Step 2: Notify user to review the content
@@ -105,7 +107,6 @@ static async Task<object> RunOrchestratorAsync(TaskOrchestrationContext context,
                {
                    message = $"Human approval timed out after {input.ApprovalTimeoutHours} hour(s). Treating as rejection.",
                    iterationCount,
-                    content
                });
            throw new TimeoutException($"Human approval timed out after {input.ApprovalTimeoutHours} hour(s).");
        }
@@ -115,7 +116,7 @@ static async Task<object> RunOrchestratorAsync(TaskOrchestrationContext context,
            context.SetCustomStatus(new
            {
                message = "Content approved by human reviewer. Publishing content...",
-                content
+                contentTitle = content.Title,
            });

            // Step 4: Publish the approved content
@@ -125,7 +126,7 @@ static async Task<object> RunOrchestratorAsync(TaskOrchestrationContext context,
            {
                message = $"Content published successfully at {context.CurrentUtcDateTime:s}",
                humanFeedback = humanResponse,
-                content
+                contentTitle = content.Title,
            });
            return new { content = content.Content };
        }
@@ -134,7 +135,7 @@ static async Task<object> RunOrchestratorAsync(TaskOrchestrationContext context,
        {
            message = "Content rejected by human reviewer. Incorporating feedback and regenerating...",
            humanFeedback = humanResponse,
-            content
+            contentTitle = content.Title,
        });

        // Incorporate human feedback and regenerate
@@ -285,6 +285,7 @@ async Task ReadStreamTask(string conversationId, string? cursor, CancellationTok
        if (chunk.Text != null)
        {
            Console.Write(chunk.Text);
+            Console.Out.Flush();
        }

        // Always update lastCursor to track the latest entry ID, even if text is null
@@ -0,0 +1,35 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+    <AzureFunctionsVersion>v4</AzureFunctionsVersion>
+    <OutputType>Exe</OutputType>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <!-- The Functions build tools don't like namespaces that start with a number -->
+    <AssemblyName>WorkflowMcpTool</AssemblyName>
+    <RootNamespace>WorkflowMcpTool</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
+  </ItemGroup>
+
+  <!-- Azure Functions packages -->
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Azure.Functions.Worker" />
+    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.DurableTask" />
+    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.DurableTask.AzureManaged" />
+    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore" />
+    <PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" />
+  </ItemGroup>
+
+  <!-- Local projects that should be switched to package references when using the sample outside of this MAF repo -->
+  <!--
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Agents.AI.Hosting.AzureFunctions" />
+  </ItemGroup>
+  -->
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.Hosting.AzureFunctions\Microsoft.Agents.AI.Hosting.AzureFunctions.csproj" />
+  </ItemGroup>
+</Project>
@@ -0,0 +1,59 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Microsoft.Agents.AI.Workflows;
+
+namespace WorkflowMcpTool;
+
+internal sealed class TranslateText() : Executor<string, TranslationResult>("TranslateText")
+{
+    public override ValueTask<TranslationResult> HandleAsync(
+        string message,
+        IWorkflowContext context,
+        CancellationToken cancellationToken = default)
+    {
+        Console.WriteLine($"[Activity] TranslateText: '{message}'");
+        return ValueTask.FromResult(new TranslationResult(message, message.ToUpperInvariant()));
+    }
+}
+
+internal sealed class FormatOutput() : Executor<TranslationResult, string>("FormatOutput")
+{
+    public override ValueTask<string> HandleAsync(
+        TranslationResult message,
+        IWorkflowContext context,
+        CancellationToken cancellationToken = default)
+    {
+        Console.WriteLine("[Activity] FormatOutput: Formatting result");
+        return ValueTask.FromResult($"Original: {message.Original} => Translated: {message.Translated}");
+    }
+}
+
+internal sealed class LookupOrder() : Executor<string, OrderInfo>("LookupOrder")
+{
+    public override ValueTask<OrderInfo> HandleAsync(
+        string message,
+        IWorkflowContext context,
+        CancellationToken cancellationToken = default)
+    {
+        Console.WriteLine($"[Activity] LookupOrder: '{message}'");
+        return ValueTask.FromResult(new OrderInfo(message, "Alice Johnson", "Wireless Headphones", Quantity: 2, UnitPrice: 49.99m));
+    }
+}
+
+internal sealed class EnrichOrder() : Executor<OrderInfo, OrderSummary>("EnrichOrder")
+{
+    public override ValueTask<OrderSummary> HandleAsync(
+        OrderInfo message,
+        IWorkflowContext context,
+        CancellationToken cancellationToken = default)
+    {
+        Console.WriteLine($"[Activity] EnrichOrder: '{message.OrderId}'");
+        return ValueTask.FromResult(new OrderSummary(message, TotalPrice: message.Quantity * message.UnitPrice, Status: "Confirmed"));
+    }
+}
+
+internal sealed record TranslationResult(string Original, string Translated);
+
+internal sealed record OrderInfo(string OrderId, string CustomerName, string Product, int Quantity, decimal UnitPrice);
+
+internal sealed record OrderSummary(OrderInfo Order, decimal TotalPrice, string Status);
@@ -0,0 +1,44 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// This sample demonstrates how to expose a durable workflow as an MCP (Model Context Protocol) tool.
+// When using AddWorkflow with exposeMcpToolTrigger: true, the Functions host will automatically
+// generate a remote MCP endpoint for the app at /runtime/webhooks/mcp with a workflow-specific
+// tool name. MCP-compatible clients can then invoke the workflow as a tool.
+
+using Microsoft.Agents.AI.Hosting.AzureFunctions;
+using Microsoft.Agents.AI.Workflows;
+using Microsoft.Azure.Functions.Worker.Builder;
+using Microsoft.Extensions.Hosting;
+using WorkflowMcpTool;
+
+// Define executors
+TranslateText translateText = new();
+FormatOutput formatOutput = new();
+LookupOrder lookupOrder = new();
+EnrichOrder enrichOrder = new();
+
+// Build a simple workflow: TranslateText -> FormatOutput
+Workflow translateWorkflow = new WorkflowBuilder(translateText)
+    .WithName("Translate")
+    .WithDescription("Translate text to uppercase and format the result")
+    .AddEdge(translateText, formatOutput)
+    .Build();
+
+// Build a workflow that returns a POCO: LookupOrder -> EnrichOrder
+Workflow orderLookupWorkflow = new WorkflowBuilder(lookupOrder)
+    .WithName("OrderLookup")
+    .WithDescription("Look up an order by ID and return enriched order details")
+    .AddEdge(lookupOrder, enrichOrder)
+    .Build();
+
+using IHost app = FunctionsApplication
+    .CreateBuilder(args)
+    .ConfigureFunctionsWebApplication()
+    .ConfigureDurableWorkflows(workflows =>
+    {
+        // Expose both workflows as MCP tool triggers.
+        workflows.AddWorkflow(translateWorkflow, exposeStatusEndpoint: false, exposeMcpToolTrigger: true);
+        workflows.AddWorkflow(orderLookupWorkflow, exposeStatusEndpoint: false, exposeMcpToolTrigger: true);
+    })
+    .Build();
+app.Run();
@@ -0,0 +1,81 @@
+# Workflow as MCP Tool Sample
+
+This sample demonstrates how to expose durable workflows as [MCP (Model Context Protocol)](https://modelcontextprotocol.io/) tools, enabling MCP-compatible clients to invoke workflows directly.
+
+## Key Concepts Demonstrated
+
+- **Workflow as MCP Tool**: Expose workflows as callable MCP tools using `exposeMcpToolTrigger: true`
+- **MCP Server Hosting**: The Azure Functions host automatically generates a remote MCP endpoint at `/runtime/webhooks/mcp`
+- **String and POCO Results**: Shows workflows returning both plain strings and structured JSON objects
+
+## Sample Architecture
+
+The sample creates two workflows exposed as MCP tools:
+
+### Translate Workflow (returns a string)
+
+| Executor | Input | Output | Description |
+|----------|-------|--------|-------------|
+| **TranslateText** | `string` | `TranslationResult` | Converts input text to uppercase |
+| **FormatOutput** | `TranslationResult` | `string` | Formats the result into a readable string |
+
+### OrderLookup Workflow (returns a POCO)
+
+| Executor | Input | Output | Description |
+|----------|-------|--------|-------------|
+| **LookupOrder** | `string` | `OrderInfo` | Looks up an order by ID |
+| **EnrichOrder** | `OrderInfo` | `OrderSummary` | Adds computed fields (total price, status) |
+
+## Environment Setup
+
+See the [README.md](../../README.md) file in the parent directory for complete setup instructions, including:
+
+- Prerequisites installation
+- Durable Task Scheduler setup
+- Storage emulator configuration
+
+For this sample, you'll also need [Node.js](https://nodejs.org/en/download) to use the [MCP Inspector](https://modelcontextprotocol.io/docs/tools/inspector).
+
+## Running the Sample
+
+1. **Start the Function App**:
+
+   ```bash
+   cd dotnet/samples/04-hosting/DurableWorkflows/AzureFunctions/04_WorkflowMcpTool
+   func start
+   ```
+
+2. **Note the MCP Server Endpoint**: When the app starts, you'll see the MCP server endpoint in the terminal output:
+
+   ```text
+   MCP server endpoint:  http://localhost:7071/runtime/webhooks/mcp
+   ```
+
+## Invoking Workflows via MCP Inspector
+
+1. Install and run the [MCP Inspector](https://modelcontextprotocol.io/docs/tools/inspector):
+
+   ```bash
+   npx @modelcontextprotocol/inspector
+   ```
+
+2. Connect to the MCP server endpoint:
+   - For **Transport Type**, select **"Streamable HTTP"**
+   - For **URL**, enter `http://localhost:7071/runtime/webhooks/mcp`
+   - Click the **Connect** button
+
+3. Click the **List Tools** button. You should see two tools: `Translate` and `OrderLookup`.
+
+4. Test the **Translate** tool (returns a plain string):
+   - Select the `Translate` tool
+   - Set `hello world` as the `input` parameter
+   - Click **Run Tool**
+   - Expected result: `Original: hello world => Translated: HELLO WORLD`
+
+5. Test the **OrderLookup** tool (returns a JSON object):
+   - Select the `OrderLookup` tool
+   - Set `ORD-2025-42` as the `input` parameter
+   - Click **Run Tool**
+   - Expected result: A JSON object containing order details such as `OrderId`, `CustomerName`, `Product`, `TotalPrice`, and `Status`
+
+You'll see the workflow executor activities logged in the terminal where you ran `func start`.
@@ -0,0 +1,20 @@
+{
+  "version": "2.0",
+  "logging": {
+    "logLevel": {
+      "Microsoft.Agents.AI.DurableTask": "Information",
+      "Microsoft.Agents.AI.Hosting.AzureFunctions": "Information",
+      "DurableTask": "Information",
+      "Microsoft.DurableTask": "Information"
+    }
+  },
+  "extensions": {
+    "durableTask": {
+      "hubName": "default",
+      "storageProvider": {
+        "type": "AzureManaged",
+        "connectionStringName": "DURABLE_TASK_SCHEDULER_CONNECTION_STRING"
+      }
+    }
+  }
+}
@@ -0,0 +1,8 @@
+{
+  "IsEncrypted": false,
+  "Values": {
+    "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
+    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
+    "DURABLE_TASK_SCHEDULER_CONNECTION_STRING": "Endpoint=http://localhost:8080;TaskHub=default;Authentication=None"
+  }
+}
@@ -0,0 +1,42 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+    <AzureFunctionsVersion>v4</AzureFunctionsVersion>
+    <OutputType>Exe</OutputType>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <!-- The Functions build tools don't like namespaces that start with a number -->
+    <AssemblyName>WorkflowAndAgents</AssemblyName>
+    <RootNamespace>WorkflowAndAgents</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
+  </ItemGroup>
+
+  <!-- Azure Functions packages -->
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Azure.Functions.Worker" />
+    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.DurableTask" />
+    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.DurableTask.AzureManaged" />
+    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore" />
+    <PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Azure.AI.OpenAI" />
+    <PackageReference Include="Azure.Identity" />
+  </ItemGroup>
+
+  <!-- Local projects that should be switched to package references when using the sample outside of this MAF repo -->
+  <!--
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Agents.AI.Hosting.AzureFunctions" />
+    <PackageReference Include="Microsoft.Agents.AI.OpenAI" />
+  </ItemGroup>
+  -->
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.Hosting.AzureFunctions\Microsoft.Agents.AI.Hosting.AzureFunctions.csproj" />
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.OpenAI\Microsoft.Agents.AI.OpenAI.csproj" />
+  </ItemGroup>
+</Project>
@@ -0,0 +1,31 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Microsoft.Agents.AI.Workflows;
+
+namespace WorkflowAndAgents;
+
+internal sealed class TranslateText() : Executor<string, TranslationResult>("TranslateText")
+{
+    public override ValueTask<TranslationResult> HandleAsync(
+        string message,
+        IWorkflowContext context,
+        CancellationToken cancellationToken = default)
+    {
+        Console.WriteLine($"[Activity] TranslateText: '{message}'");
+        return ValueTask.FromResult(new TranslationResult(message, message.ToUpperInvariant()));
+    }
+}
+
+internal sealed class FormatOutput() : Executor<TranslationResult, string>("FormatOutput")
+{
+    public override ValueTask<string> HandleAsync(
+        TranslationResult message,
+        IWorkflowContext context,
+        CancellationToken cancellationToken = default)
+    {
+        Console.WriteLine("[Activity] FormatOutput: Formatting result");
+        return ValueTask.FromResult($"Original: {message.Original} => Translated: {message.Translated}");
+    }
+}
+
+internal sealed record TranslationResult(string Original, string Translated);
@@ -0,0 +1,64 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// This sample demonstrates using ConfigureDurableOptions to register BOTH agents AND workflows
+// in a single Azure Functions app. It uses a workflow to translate text and a standalone AI agent
+// accessible via HTTP and MCP tool triggers.
+
+#pragma warning disable IDE0002 // Simplify Member Access
+
+using Azure;
+using Azure.AI.OpenAI;
+using Azure.Identity;
+using Microsoft.Agents.AI;
+using Microsoft.Agents.AI.Hosting.AzureFunctions;
+using Microsoft.Agents.AI.Workflows;
+using Microsoft.Azure.Functions.Worker.Builder;
+using Microsoft.Extensions.Hosting;
+using OpenAI.Chat;
+using WorkflowAndAgents;
+
+// Get the Azure OpenAI endpoint and deployment name from environment variables.
+string endpoint = Environment.GetEnvironmentVariable("AZURE_OPENAI_ENDPOINT")
+    ?? throw new InvalidOperationException("AZURE_OPENAI_ENDPOINT is not set.");
+string deploymentName = Environment.GetEnvironmentVariable("AZURE_OPENAI_DEPLOYMENT_NAME")
+    ?? throw new InvalidOperationException("AZURE_OPENAI_DEPLOYMENT_NAME is not set.");
+
+// Use Azure Key Credential if provided, otherwise use Azure CLI Credential.
+string? azureOpenAiKey = Environment.GetEnvironmentVariable("AZURE_OPENAI_API_KEY");
+AzureOpenAIClient client = !string.IsNullOrEmpty(azureOpenAiKey)
+    ? new AzureOpenAIClient(new Uri(endpoint), new AzureKeyCredential(azureOpenAiKey))
+    : new AzureOpenAIClient(new Uri(endpoint), new DefaultAzureCredential());
+
+ChatClient chatClient = client.GetChatClient(deploymentName);
+
+// Define a standalone AI agent
+AIAgent assistant = chatClient.AsAIAgent(
+    "You are a helpful assistant. Answer questions clearly and concisely.",
+    "Assistant",
+    description: "A general-purpose helpful assistant.");
+
+// Define workflow executors
+TranslateText translateText = new();
+FormatOutput formatOutput = new();
+
+// Build a workflow: TranslateText -> FormatOutput
+Workflow translateWorkflow = new WorkflowBuilder(translateText)
+    .WithName("Translate")
+    .WithDescription("Translate text to uppercase and format the result")
+    .AddEdge(translateText, formatOutput)
+    .Build();
+
+// Use ConfigureDurableOptions to register both agents and workflows together
+using IHost app = FunctionsApplication
+    .CreateBuilder(args)
+    .ConfigureFunctionsWebApplication()
+    .ConfigureDurableOptions(options =>
+    {
+        // Register the standalone agent with HTTP and MCP tool triggers
+        options.Agents.AddAIAgent(assistant, enableHttpTrigger: true, enableMcpToolTrigger: true);
+
+        // Register the workflow with an HTTP endpoint and MCP tool trigger
+        options.Workflows.AddWorkflow(translateWorkflow, exposeStatusEndpoint: false, exposeMcpToolTrigger: true);
+    })
+    .Build();
+app.Run();
@@ -0,0 +1,76 @@
+# Workflow and Agents Sample
+
+This sample demonstrates how to use `ConfigureDurableOptions` to register **both** AI agents **and** workflows in a single Azure Functions app. This is the recommended approach when your application needs both standalone agents and orchestrated workflows.
+
+## Key Concepts Demonstrated
+
+- **Unified Configuration**: Use `ConfigureDurableOptions` to register agents and workflows together
+- **Standalone Agent**: An AI agent accessible via HTTP and MCP tool triggers
+- **Workflow**: A simple text translation workflow also exposed as an MCP tool
+- **Mixed Triggers**: Both agents and workflows coexist in the same Functions host
+
+## Sample Architecture
+
+### Standalone Agent
+
+| Agent | Description |
+|-------|-------------|
+| **Assistant** | A general-purpose AI assistant accessible via HTTP (`/agents/Assistant/run`) and as an MCP tool |
+
+### Translate Workflow
+
+| Executor | Input | Output | Description |
+|----------|-------|--------|-------------|
+| **TranslateText** | `string` | `TranslationResult` | Converts input text to uppercase |
+| **FormatOutput** | `TranslationResult` | `string` | Formats the result into a readable string |
+
+## Environment Setup
+
+See the [README.md](../../README.md) file in the parent directory for complete setup instructions, including:
+
+- Prerequisites installation
+- Durable Task Scheduler setup
+- Storage emulator configuration
+
+This sample also requires Azure OpenAI credentials. Set the following in `local.settings.json`:
+
+- `AZURE_OPENAI_ENDPOINT`: Your Azure OpenAI endpoint URL
+- `AZURE_OPENAI_DEPLOYMENT_NAME`: Your chat model deployment name
+- `AZURE_OPENAI_API_KEY` (optional): If not set, Azure CLI credential is used
+
+## Running the Sample
+
+1. **Start the Function App**:
+
+   ```bash
+   cd dotnet/samples/04-hosting/DurableWorkflows/AzureFunctions/05_WorkflowAndAgents
+   func start
+   ```
+
+2. **Expected Functions**: When the app starts, you should see functions for both the agent and the workflow:
+
+   - `dafx-Assistant` (entity trigger for the agent)
+   - `http-Assistant` (HTTP trigger for the agent)
+   - `mcptool-Assistant` (MCP tool trigger for the agent)
+   - `wf-Translate` (orchestration trigger for the workflow)
+   - `mcptool-wf-Translate` (MCP tool trigger for the workflow)
+
+## Invoking the Agent via HTTP
+
+```bash
+curl -X POST http://localhost:7071/agents/Assistant/run \
+  -H "Content-Type: application/json" \
+  -d '{"query": "What is the capital of France?"}'
+```
+
+## Invoking via MCP Inspector
+
+1. Install and run the [MCP Inspector](https://modelcontextprotocol.io/docs/tools/inspector):
+
+   ```bash
+   npx @modelcontextprotocol/inspector
+   ```
+
+2. Connect to `http://localhost:7071/runtime/webhooks/mcp` using **Streamable HTTP** transport.
+
+3. Click **List Tools** to see both the `Assistant` agent tool and the `Translate` workflow tool.
@@ -0,0 +1,20 @@
+{
+  "version": "2.0",
+  "logging": {
+    "logLevel": {
+      "Microsoft.Agents.AI.DurableTask": "Information",
+      "Microsoft.Agents.AI.Hosting.AzureFunctions": "Information",
+      "DurableTask": "Information",
+      "Microsoft.DurableTask": "Information"
+    }
+  },
+  "extensions": {
+    "durableTask": {
+      "hubName": "default",
+      "storageProvider": {
+        "type": "AzureManaged",
+        "connectionStringName": "DURABLE_TASK_SCHEDULER_CONNECTION_STRING"
+      }
+    }
+  }
+}
@@ -0,0 +1,10 @@
+{
+  "IsEncrypted": false,
+  "Values": {
+    "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
+    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
+    "DURABLE_TASK_SCHEDULER_CONNECTION_STRING": "Endpoint=http://localhost:8080;TaskHub=default;Authentication=None",
+    "AZURE_OPENAI_ENDPOINT": "<AZURE_OPENAI_ENDPOINT>",
+    "AZURE_OPENAI_DEPLOYMENT_NAME": "<AZURE_OPENAI_DEPLOYMENT_NAME>"
+  }
+}
@@ -48,3 +48,4 @@ $env:DURABLE_TASK_SCHEDULER_CONNECTION_STRING = "AccountEndpoint=http://localhos
 | [01_SequentialWorkflow](AzureFunctions/01_SequentialWorkflow/) | Sequential workflow hosted in Azure Functions |
 | [02_ConcurrentWorkflow](AzureFunctions/02_ConcurrentWorkflow/) | Concurrent workflow hosted in Azure Functions |
 | [03_WorkflowHITL](AzureFunctions/03_WorkflowHITL/) | Human-in-the-loop workflow hosted in Azure Functions |
+| [04_WorkflowMcpTool](AzureFunctions/04_WorkflowMcpTool/) | Workflow exposed as an MCP tool |
@@ -59,7 +59,7 @@ internal static class HostAgentFactory
            PushNotifications = false,
        };

-        var invoiceQuery = new AgentSkill()
+        var invoiceQuery = new A2A.AgentSkill()
        {
            Id = "id_invoice_agent",
            Name = "InvoiceQuery",
@@ -91,7 +91,7 @@ internal static class HostAgentFactory
            PushNotifications = false,
        };

-        var policyQuery = new AgentSkill()
+        var policyQuery = new A2A.AgentSkill()
        {
            Id = "id_policy_agent",
            Name = "PolicyAgent",
@@ -123,7 +123,7 @@ internal static class HostAgentFactory
            PushNotifications = false,
        };

-        var logisticsQuery = new AgentSkill()
+        var logisticsQuery = new A2A.AgentSkill()
        {
            Id = "id_logistics_agent",
            Name = "LogisticsQuery",
@@ -0,0 +1,60 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.Extensions.AI;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+using OpenAI.Responses;
+
+namespace Azure.AI.Extensions.OpenAI;
+
+/// <summary>
+/// Provides extension methods for <see cref="ProjectResponsesClient"/>
+/// to simplify the creation of AI agents that work with Azure AI services.
+/// </summary>
+[Experimental(DiagnosticIds.Experiments.AIOpenAIResponses)]
+public static class ProjectResponsesClientExtensions
+{
+    /// <summary>
+    /// Gets an <see cref="IChatClient"/> for use with this <see cref="ProjectResponsesClient"/> that does not store responses for later retrieval.
+    /// </summary>
+    /// <remarks>
+    /// This corresponds to setting the "store" property in the JSON representation to false.
+    /// </remarks>
+    /// <param name="responseClient">The client.</param>
+    /// <param name="deploymentName">Optional deployment name (model) to use for requests.</param>
+    /// <param name="includeReasoningEncryptedContent">
+    /// Includes an encrypted version of reasoning tokens in reasoning item outputs.
+    /// This enables reasoning items to be used in multi-turn conversations when using the Responses API statelessly
+    /// (like when the store parameter is set to false, or when an organization is enrolled in the zero data retention program).
+    /// Defaults to <see langword="true"/>.
+    /// </param>
+    /// <returns>An <see cref="IChatClient"/> that can be used to converse via the <see cref="ProjectResponsesClient"/> that does not store responses for later retrieval.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="responseClient"/> is <see langword="null"/>.</exception>
+    [Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+    public static IChatClient AsIChatClientWithStoredOutputDisabled(this ProjectResponsesClient responseClient, string? deploymentName = null, bool includeReasoningEncryptedContent = true)
+    {
+        return Throw.IfNull(responseClient)
+            .AsIChatClient(deploymentName)
+            .AsBuilder()
+            .ConfigureOptions(x =>
+            {
+                var previousFactory = x.RawRepresentationFactory;
+                x.RawRepresentationFactory = state =>
+                {
+                    var responseOptions = previousFactory?.Invoke(state) as CreateResponseOptions ?? new CreateResponseOptions();
+
+                    responseOptions.StoredOutputEnabled = false;
+
+                    if (includeReasoningEncryptedContent &&
+                        !responseOptions.IncludedProperties.Contains(IncludedResponseProperty.ReasoningEncryptedContent))
+                    {
+                        responseOptions.IncludedProperties.Add(IncludedResponseProperty.ReasoningEncryptedContent);
+                    }
+
+                    return responseOptions;
+                };
+            })
+            .Build();
+    }
+}
@@ -167,6 +167,20 @@ internal sealed class BuiltInFunctionExecutor : IFunctionExecutor
            return;
        }

+        if (context.FunctionDefinition.EntryPoint == BuiltInFunctions.RunWorkflowMcpToolFunctionEntryPoint)
+        {
+            if (mcpToolInvocationContext is null)
+            {
+                throw new InvalidOperationException($"MCP tool invocation context binding is missing for the invocation {context.InvocationId}.");
+            }
+
+            context.GetInvocationResult().Value = await BuiltInFunctions.RunWorkflowMcpToolAsync(
+                mcpToolInvocationContext,
+                durableTaskClient,
+                context);
+            return;
+        }
+
        throw new InvalidOperationException($"Unsupported function entry point '{context.FunctionDefinition.EntryPoint}' for invocation {context.InvocationId}.");
    }

@@ -29,6 +29,7 @@ internal static class BuiltInFunctions
    internal static readonly string InvokeWorkflowActivityFunctionEntryPoint = $"{typeof(BuiltInFunctions).FullName!}.{nameof(InvokeWorkflowActivityAsync)}";
    internal static readonly string GetWorkflowStatusHttpFunctionEntryPoint = $"{typeof(BuiltInFunctions).FullName!}.{nameof(GetWorkflowStatusAsync)}";
    internal static readonly string RespondToWorkflowHttpFunctionEntryPoint = $"{typeof(BuiltInFunctions).FullName!}.{nameof(RespondToWorkflowAsync)}";
+    internal static readonly string RunWorkflowMcpToolFunctionEntryPoint = $"{typeof(BuiltInFunctions).FullName!}.{nameof(RunWorkflowMcpToolAsync)}";

 #pragma warning disable IL3000 // Avoid accessing Assembly file path when publishing as a single file - Azure Functions does not use single-file publishing
    internal static readonly string ScriptFile = Path.GetFileName(typeof(BuiltInFunctions).Assembly.Location);
@@ -378,6 +379,55 @@ internal static class BuiltInFunctions
        return agentResponse.Text;
    }

+    /// <summary>
+    /// Runs a workflow via MCP tool trigger.
+    /// Extracts the <c>input</c> argument, schedules a new orchestration, waits for completion, and returns the output.
+    /// </summary>
+    public static async Task<string?> RunWorkflowMcpToolAsync(
+        [McpToolTrigger("BuiltInWorkflowMcpTool")] ToolInvocationContext context,
+        [DurableClient] DurableTaskClient client,
+        FunctionContext functionContext)
+    {
+        if (context.Arguments is null)
+        {
+            throw new ArgumentException("MCP Tool invocation is missing required arguments.");
+        }
+
+        if (!context.Arguments.TryGetValue("input", out object? inputObj) || inputObj is not string input)
+        {
+            throw new ArgumentException("MCP Tool invocation is missing required 'input' argument of type string.");
+        }
+
+        string workflowName = context.Name;
+        string orchestrationFunctionName = WorkflowNamingHelper.ToOrchestrationFunctionName(workflowName);
+
+        DurableWorkflowInput<string> orchestrationInput = new() { Input = input };
+        string instanceId = await client.ScheduleNewOrchestrationInstanceAsync(orchestrationFunctionName, orchestrationInput);
+
+        OrchestrationMetadata? metadata = await client.WaitForInstanceCompletionAsync(
+            instanceId,
+            getInputsAndOutputs: true,
+            cancellation: functionContext.CancellationToken);
+
+        if (metadata is null)
+        {
+            throw new InvalidOperationException($"Workflow orchestration '{instanceId}' returned no metadata.");
+        }
+
+        if (metadata.RuntimeStatus is OrchestrationRuntimeStatus.Failed)
+        {
+            string errorMessage = metadata.FailureDetails?.ErrorMessage ?? "Unknown error";
+            throw new InvalidOperationException($"Workflow orchestration '{instanceId}' failed: {errorMessage}");
+        }
+
+        if (metadata.RuntimeStatus is not OrchestrationRuntimeStatus.Completed)
+        {
+            throw new InvalidOperationException($"Workflow orchestration '{instanceId}' ended with unexpected status '{metadata.RuntimeStatus}'.");
+        }
+
+        return metadata.ReadOutputAs<DurableWorkflowResult>()?.Result;
+    }
+
    /// <summary>
    /// Creates an error response with the specified status code and error message.
    /// </summary>
@@ -2,6 +2,7 @@

 ## [Unreleased]

+- Added MCP tool trigger support for durable workflows ([#4768](https://github.com/microsoft/agent-framework/pull/4768))
 - Added Azure Functions hosting support for durable workflows ([#4436](https://github.com/microsoft/agent-framework/pull/4436))

 ## v1.0.0-preview.251219.1
@@ -6,7 +6,8 @@ namespace Microsoft.Agents.AI.Hosting.AzureFunctions;

 /// <summary>
 /// Provides access to agent-specific options for functions agents by name.
-/// Returns default options (HTTP trigger enabled, MCP tool disabled) when no explicit options were configured.
+/// Returns <see langword="false"/> when no explicit options have been configured for an agent,
+/// which distinguishes standalone agents from those auto-registered by workflows.
 /// </summary>
 internal sealed class DefaultFunctionsAgentOptionsProvider(IReadOnlyDictionary<string, FunctionsAgentOptions> functionsAgentOptions)
    : IFunctionsAgentOptionsProvider
@@ -14,32 +15,19 @@ internal sealed class DefaultFunctionsAgentOptionsProvider(IReadOnlyDictionary<s
    private readonly IReadOnlyDictionary<string, FunctionsAgentOptions> _functionsAgentOptions =
        functionsAgentOptions ?? throw new ArgumentNullException(nameof(functionsAgentOptions));

-    // Default options. HTTP trigger enabled, MCP tool disabled.
-    private static readonly FunctionsAgentOptions s_defaultOptions = new()
-    {
-        HttpTrigger = { IsEnabled = true },
-        McpToolTrigger = { IsEnabled = false }
-    };
-
    /// <summary>
    /// Attempts to retrieve the options associated with the specified agent name.
-    /// If not found, a default options instance (with HTTP trigger enabled) is returned.
+    /// Returns <see langword="false"/> when no options have been explicitly configured for the agent.
    /// </summary>
    /// <param name="agentName">The name of the agent whose options are to be retrieved. Cannot be null or empty.</param>
-    /// <param name="options">The options for the specified agent. Will never be null.</param>
-    /// <returns>Always true. Returns configured options if present; otherwise default fallback options.</returns>
+    /// <param name="options">
+    /// When this method returns <see langword="true"/>, contains the options for the specified agent;
+    /// otherwise, <see langword="null"/>.
+    /// </param>
+    /// <returns><see langword="true"/> if options were found for the agent; otherwise, <see langword="false"/>.</returns>
    public bool TryGet(string agentName, [NotNullWhen(true)] out FunctionsAgentOptions? options)
    {
        ArgumentException.ThrowIfNullOrEmpty(agentName);
-
-        if (this._functionsAgentOptions.TryGetValue(agentName, out FunctionsAgentOptions? existing))
-        {
-            options = existing;
-            return true;
-        }
-
-        // If not defined, return default options.
-        options = s_defaultOptions;
-        return true;
+        return this._functionsAgentOptions.TryGetValue(agentName, out options);
    }
 }
@@ -6,9 +6,13 @@ using Microsoft.Extensions.Logging;
 namespace Microsoft.Agents.AI.Hosting.AzureFunctions;

 /// <summary>
-/// Transforms function metadata by registering durable agent functions for each configured agent.
+/// Transforms function metadata by registering durable agent functions for each explicitly configured agent.
 /// </summary>
-/// <remarks>This transformer adds both entity trigger and HTTP trigger functions for every agent registered in the application.</remarks>
+/// <remarks>
+/// This transformer adds entity, HTTP, and MCP tool trigger functions for agents that have
+/// explicit <see cref="FunctionsAgentOptions"/>. Agents auto-registered by workflows
+/// (which lack explicit options) are handled by <see cref="DurableWorkflowsFunctionMetadataTransformer"/>.
+/// </remarks>
 internal sealed class DurableAgentFunctionMetadataTransformer : IFunctionMetadataTransformer
 {
    private readonly ILogger<DurableAgentFunctionMetadataTransformer> _logger;
@@ -38,24 +42,27 @@ internal sealed class DurableAgentFunctionMetadataTransformer : IFunctionMetadat
        {
            string agentName = kvp.Key;

-            this._logger.LogRegisteringTriggerForAgent(agentName, "entity");
+            // Only generate triggers for agents with explicit Functions agent options.
+            // Agents auto-registered by workflows are handled by DurableWorkflowsFunctionMetadataTransformer.
+            if (!this._functionsAgentOptionsProvider.TryGet(agentName, out FunctionsAgentOptions? agentTriggerOptions))
+            {
+                continue;
+            }

+            this._logger.LogRegisteringTriggerForAgent(agentName, "entity");
            original.Add(FunctionMetadataFactory.CreateEntityTrigger(agentName));

-            if (this._functionsAgentOptionsProvider.TryGet(agentName, out FunctionsAgentOptions? agentTriggerOptions))
+            if (agentTriggerOptions.HttpTrigger.IsEnabled)
            {
-                if (agentTriggerOptions.HttpTrigger.IsEnabled)
-                {
-                    this._logger.LogRegisteringTriggerForAgent(agentName, "http");
-                    original.Add(FunctionMetadataFactory.CreateHttpTrigger(agentName, $"agents/{agentName}/run", BuiltInFunctions.RunAgentHttpFunctionEntryPoint));
-                }
+                this._logger.LogRegisteringTriggerForAgent(agentName, "http");
+                original.Add(FunctionMetadataFactory.CreateHttpTrigger(agentName, $"agents/{agentName}/run", BuiltInFunctions.RunAgentHttpFunctionEntryPoint));
+            }

-                if (agentTriggerOptions.McpToolTrigger.IsEnabled)
-                {
-                    AIAgent agent = kvp.Value(this._serviceProvider);
-                    this._logger.LogRegisteringTriggerForAgent(agentName, "mcpTool");
-                    original.Add(CreateMcpToolTrigger(agentName, agent.Description));
-                }
+            if (agentTriggerOptions.McpToolTrigger.IsEnabled)
+            {
+                AIAgent agent = kvp.Value(this._serviceProvider);
+                this._logger.LogRegisteringTriggerForAgent(agentName, "mcpTool");
+                original.Add(CreateMcpToolTrigger(agentName, agent.Description));
            }
        }
    }
@@ -134,4 +134,17 @@ public static class DurableAgentsOptionsExtensions
    {
        return new Dictionary<string, FunctionsAgentOptions>(s_agentOptions, StringComparer.OrdinalIgnoreCase);
    }
+
+    /// <summary>
+    /// Ensures every agent in <paramref name="agentNames"/> has an entry in the
+    /// options registry. Agents that already have explicit options are left untouched.
+    /// New entries receive the default configuration (HTTP trigger enabled, MCP tool disabled).
+    /// </summary>
+    internal static void EnsureDefaultOptionsForAll(IEnumerable<string> agentNames)
+    {
+        foreach (string name in agentNames)
+        {
+            s_agentOptions.TryAdd(name, new FunctionsAgentOptions { HttpTrigger = { IsEnabled = true } });
+        }
+    }
 }
@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.

+using System.Text.Json.Nodes;
 using Microsoft.Agents.AI.DurableTask;
 using Microsoft.Azure.Functions.Worker.Core.FunctionMetadata;

@@ -98,4 +99,65 @@ internal static class FunctionMetadataFactory
            ScriptFile = BuiltInFunctions.ScriptFile,
        };
    }
+
+    /// <summary>
+    /// Creates function metadata for an MCP tool trigger function that starts a workflow.
+    /// </summary>
+    /// <param name="workflowName">The name of the workflow to expose as an MCP tool.</param>
+    /// <param name="description">An optional description for the MCP tool. If null, a default description is generated.</param>
+    /// <returns>A <see cref="DefaultFunctionMetadata"/> configured for an MCP tool trigger.</returns>
+    internal static DefaultFunctionMetadata CreateWorkflowMcpToolTrigger(
+        string workflowName,
+        string? description)
+    {
+        var functionName = $"{BuiltInFunctions.McpToolPrefix}{workflowName}";
+        var toolDescription = description ?? $"Run the {workflowName} workflow";
+
+        var toolProperties = new JsonArray(new JsonObject
+        {
+            ["propertyName"] = "input",
+            ["propertyType"] = "string",
+            ["description"] = "The input to the workflow.",
+            ["isRequired"] = true,
+            ["isArray"] = false,
+        });
+
+        var triggerBinding = new JsonObject
+        {
+            ["name"] = "context",
+            ["type"] = "mcpToolTrigger",
+            ["direction"] = "In",
+            ["toolName"] = workflowName,
+            ["description"] = toolDescription,
+            ["toolProperties"] = toolProperties.ToJsonString(),
+        };
+
+        var inputBinding = new JsonObject
+        {
+            ["name"] = "input",
+            ["type"] = "mcpToolProperty",
+            ["direction"] = "In",
+            ["propertyName"] = "input",
+            ["description"] = "The input to the workflow",
+            ["isRequired"] = true,
+            ["dataType"] = "String",
+            ["propertyType"] = "string",
+        };
+
+        var clientBinding = new JsonObject
+        {
+            ["name"] = "client",
+            ["type"] = "durableClient",
+            ["direction"] = "In",
+        };
+
+        return new DefaultFunctionMetadata
+        {
+            Name = functionName,
+            Language = "dotnet-isolated",
+            RawBindings = [triggerBinding.ToJsonString(), inputBinding.ToJsonString(), clientBinding.ToJsonString()],
+            EntryPoint = BuiltInFunctions.RunWorkflowMcpToolFunctionEntryPoint,
+            ScriptFile = BuiltInFunctions.ScriptFile,
+        };
+    }
 }
@@ -27,9 +27,16 @@ public static class FunctionsApplicationBuilderExtensions
    {
        ArgumentNullException.ThrowIfNull(configure);

+        // Create/get shared options BEFORE the DurableTask library call so it can find them.
+        FunctionsDurableOptions sharedOptions = GetOrCreateSharedOptions(builder.Services);
+
        // The main agent services registration is done in Microsoft.DurableTask.Agents.
        builder.Services.ConfigureDurableAgents(configure);

+        // Ensure all agents registered through this path have default FunctionsAgentOptions.
+        // This distinguishes them from agents auto-registered by workflows.
+        DurableAgentsOptionsExtensions.EnsureDefaultOptionsForAll(sharedOptions.Agents.GetAgentFactories().Keys);
+
        builder.Services.TryAddSingleton<IFunctionsAgentOptionsProvider>(_ =>
            new DefaultFunctionsAgentOptionsProvider(DurableAgentsOptionsExtensions.GetAgentOptionsSnapshot()));

@@ -67,6 +74,13 @@ public static class FunctionsApplicationBuilderExtensions

        builder.Services.ConfigureDurableOptions(configure);

+        if (DurableAgentsOptionsExtensions.GetAgentOptionsSnapshot().Count > 0)
+        {
+            builder.Services.TryAddSingleton<IFunctionsAgentOptionsProvider>(_ =>
+                new DefaultFunctionsAgentOptionsProvider(DurableAgentsOptionsExtensions.GetAgentOptionsSnapshot()));
+            builder.Services.TryAddEnumerable(ServiceDescriptor.Singleton<IFunctionMetadataTransformer, DurableAgentFunctionMetadataTransformer>());
+        }
+
        if (sharedOptions.Workflows.Workflows.Count > 0)
        {
            builder.Services.TryAddEnumerable(ServiceDescriptor.Singleton<IFunctionMetadataTransformer, DurableWorkflowsFunctionMetadataTransformer>());
@@ -102,12 +116,14 @@ public static class FunctionsApplicationBuilderExtensions

        builder.UseWhen<BuiltInFunctionExecutionMiddleware>(static context =>
            string.Equals(context.FunctionDefinition.EntryPoint, BuiltInFunctions.RunAgentHttpFunctionEntryPoint, StringComparison.Ordinal) ||
+            string.Equals(context.FunctionDefinition.EntryPoint, BuiltInFunctions.RunAgentMcpToolFunctionEntryPoint, StringComparison.Ordinal) ||
            string.Equals(context.FunctionDefinition.EntryPoint, BuiltInFunctions.RunAgentEntityFunctionEntryPoint, StringComparison.Ordinal) ||
            string.Equals(context.FunctionDefinition.EntryPoint, BuiltInFunctions.RunWorkflowOrchestrationHttpFunctionEntryPoint, StringComparison.Ordinal) ||
            string.Equals(context.FunctionDefinition.EntryPoint, BuiltInFunctions.RunWorkflowOrchestrationFunctionEntryPoint, StringComparison.Ordinal) ||
            string.Equals(context.FunctionDefinition.EntryPoint, BuiltInFunctions.InvokeWorkflowActivityFunctionEntryPoint, StringComparison.Ordinal) ||
            string.Equals(context.FunctionDefinition.EntryPoint, BuiltInFunctions.GetWorkflowStatusHttpFunctionEntryPoint, StringComparison.Ordinal) ||
-            string.Equals(context.FunctionDefinition.EntryPoint, BuiltInFunctions.RespondToWorkflowHttpFunctionEntryPoint, StringComparison.Ordinal)
+            string.Equals(context.FunctionDefinition.EntryPoint, BuiltInFunctions.RespondToWorkflowHttpFunctionEntryPoint, StringComparison.Ordinal) ||
+            string.Equals(context.FunctionDefinition.EntryPoint, BuiltInFunctions.RunWorkflowMcpToolFunctionEntryPoint, StringComparison.Ordinal)
        );
        builder.Services.TryAddSingleton<BuiltInFunctionExecutor>();
    }
@@ -10,6 +10,7 @@ namespace Microsoft.Agents.AI.Hosting.AzureFunctions;
 internal sealed class FunctionsDurableOptions : DurableOptions
 {
    private readonly HashSet<string> _statusEndpointWorkflows = new(StringComparer.OrdinalIgnoreCase);
+    private readonly HashSet<string> _mcpToolTriggerWorkflows = new(StringComparer.OrdinalIgnoreCase);

    /// <summary>
    /// Enables the status HTTP endpoint for the specified workflow.
@@ -26,4 +27,20 @@ internal sealed class FunctionsDurableOptions : DurableOptions
    {
        return this._statusEndpointWorkflows.Contains(workflowName);
    }
+
+    /// <summary>
+    /// Enables the MCP tool trigger for the specified workflow.
+    /// </summary>
+    internal void EnableMcpToolTrigger(string workflowName)
+    {
+        this._mcpToolTriggerWorkflows.Add(workflowName);
+    }
+
+    /// <summary>
+    /// Returns whether the MCP tool trigger is enabled for the specified workflow.
+    /// </summary>
+    internal bool IsMcpToolTriggerEnabled(string workflowName)
+    {
+        return this._mcpToolTriggerWorkflows.Contains(workflowName);
+    }
 }
@@ -27,4 +27,31 @@ public static class DurableWorkflowOptionsExtensions
            functionsOptions.EnableStatusEndpoint(workflow.Name!);
        }
    }
+
+    /// <summary>
+    /// Adds a workflow and configures whether to expose a status HTTP endpoint and/or an MCP tool trigger.
+    /// </summary>
+    /// <param name="options">The workflow options to add the workflow to.</param>
+    /// <param name="workflow">The workflow instance to add.</param>
+    /// <param name="exposeStatusEndpoint">If <see langword="true"/>, a GET endpoint is generated at <c>workflows/{name}/status/{runId}</c>.</param>
+    /// <param name="exposeMcpToolTrigger">If <see langword="true"/>, an MCP tool trigger is generated for the workflow.</param>
+    public static void AddWorkflow(this DurableWorkflowOptions options, Workflow workflow, bool exposeStatusEndpoint, bool exposeMcpToolTrigger)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+
+        options.AddWorkflow(workflow);
+
+        if (options.ParentOptions is FunctionsDurableOptions functionsOptions)
+        {
+            if (exposeStatusEndpoint)
+            {
+                functionsOptions.EnableStatusEndpoint(workflow.Name!);
+            }
+
+            if (exposeMcpToolTrigger)
+            {
+                functionsOptions.EnableMcpToolTrigger(workflow.Name!);
+            }
+        }
+    }
 }
@@ -50,8 +50,11 @@ internal sealed class DurableWorkflowsFunctionMetadataTransformer : IFunctionMet
        int initialCount = original.Count;
        this._logger.LogTransformingFunctionMetadata(initialCount);

-        // Track registered function names to avoid duplicates when workflows share executors.
-        HashSet<string> registeredFunctions = [];
+        // Seed with existing function names to avoid duplicates across transformers
+        // (e.g., when DurableAgentFunctionMetadataTransformer already registered entity triggers).
+        HashSet<string> registeredFunctions = new(
+            original.Select(f => f.Name!),
+            StringComparer.OrdinalIgnoreCase);

        DurableWorkflowOptions workflowOptions = this._options.Workflows;
        foreach (var workflow in workflowOptions.Workflows)
@@ -113,6 +116,17 @@ internal sealed class DurableWorkflowsFunctionMetadataTransformer : IFunctionMet
                }
            }

+            // Register an MCP tool trigger if opted in via AddWorkflow(exposeMcpToolTrigger: true).
+            if (this._options.IsMcpToolTriggerEnabled(workflow.Key))
+            {
+                string mcpToolFunctionName = $"{BuiltInFunctions.McpToolPrefix}{workflow.Key}";
+                if (registeredFunctions.Add(mcpToolFunctionName))
+                {
+                    this._logger.LogRegisteringWorkflowTrigger(workflow.Key, mcpToolFunctionName, "mcpTool");
+                    original.Add(FunctionMetadataFactory.CreateWorkflowMcpToolTrigger(workflow.Key, workflow.Value.Description));
+                }
+            }
+
            // Register activity or entity functions for each executor in the workflow.
            // ReflectExecutors() returns all executors across the graph; no need to manually traverse edges.
            foreach (KeyValuePair<string, ExecutorBinding> entry in workflow.Value.ReflectExecutors())
@@ -39,14 +39,16 @@ internal abstract record ChatCompletionRequestMessage
    /// <exception cref="InvalidOperationException">Thrown when the content is neither text nor AI contents.</exception>
    public virtual ChatMessage ToChatMessage()
    {
+        var role = new ChatRole(this.Role);
+
        if (this.Content.IsText)
        {
-            return new(ChatRole.User, this.Content.Text);
+            return new(role, this.Content.Text);
        }
        else if (this.Content.IsContents)
        {
            var aiContents = this.Content.Contents.Select(MessageContentPartConverter.ToAIContent).Where(c => c is not null).ToList();
-            return new ChatMessage(ChatRole.User, aiContents!);
+            return new ChatMessage(role, aiContents!);
        }

        throw new InvalidOperationException("MessageContent has no value");
@@ -165,9 +167,11 @@ internal sealed record FunctionMessage : ChatCompletionRequestMessage
    /// <exception cref="InvalidOperationException">Thrown when the content is not text.</exception>
    public override ChatMessage ToChatMessage()
    {
+        var role = new ChatRole(this.Role);
+
        if (this.Content.IsText)
        {
-            return new(ChatRole.User, this.Content.Text);
+            return new(role, this.Content.Text);
        }

        throw new InvalidOperationException("FunctionMessage Content must be text");
@@ -105,7 +105,7 @@ public static class OpenAIResponseClientExtensions
    /// This corresponds to setting the "store" property in the JSON representation to false.
    /// </remarks>
    /// <param name="responseClient">The client.</param>
-    /// <param name="model">Optional default model ID to use for requests. Required when using a plain <see cref="ResponsesClient"/> (not via Azure OpenAI).</param>
+    /// <param name="model">Optional default model ID to use for requests.</param>
    /// <param name="includeReasoningEncryptedContent">
    /// Includes an encrypted version of reasoning tokens in reasoning item outputs.
    /// This enables reasoning items to be used in multi-turn conversations when using the Responses API statelessly
@@ -38,6 +38,7 @@ internal static class SourceBuilder
        sb.AppendLine("using System.Collections.Generic;");
        sb.AppendLine("using Microsoft.Agents.AI.Workflows;");
        sb.AppendLine();
+        sb.AppendLine("using RouteBuilder = Microsoft.Agents.AI.Workflows.RouteBuilder;");

        // Namespace
        if (!string.IsNullOrWhiteSpace(info.Namespace))
@@ -145,7 +145,7 @@ public static partial class AgentWorkflowBuilder
        return builder.Build();
    }

-    /// <summary>Creates a new <see cref="HandoffsWorkflowBuilder"/> using <paramref name="initialAgent"/> as the starting agent in the workflow.</summary>
+    /// <summary>Creates a new <see cref="HandoffWorkflowBuilder"/> using <paramref name="initialAgent"/> as the starting agent in the workflow.</summary>
    /// <param name="initialAgent">The agent that will receive inputs provided to the workflow.</param>
    /// <returns>The builder for creating a workflow based on handoffs.</returns>
    /// <remarks>
@@ -154,7 +154,7 @@ public static partial class AgentWorkflowBuilder
    /// The <see cref="AIAgent"/> must be capable of understanding those <see cref="AgentRunOptions"/> provided. If the agent
    /// ignores the tools or is otherwise unable to advertize them to the underlying provider, handoffs will not occur.
    /// </remarks>
-    public static HandoffsWorkflowBuilder CreateHandoffBuilderWith(AIAgent initialAgent)
+    public static HandoffWorkflowBuilder CreateHandoffBuilderWith(AIAgent initialAgent)
    {
        Throw.IfNull(initialAgent);
        return new(initialAgent);
@@ -5,11 +5,14 @@ using System.Collections.Generic;
 using System.IO;
 using System.Text;
 using System.Text.Json;
+using System.Text.Json.Serialization.Metadata;
 using System.Threading;
 using System.Threading.Tasks;

 namespace Microsoft.Agents.AI.Workflows.Checkpointing;

+internal record CheckpointFileIndexEntry(CheckpointInfo CheckpointInfo, string FileName);
+
 /// <summary>
 /// Provides a file system-based implementation of a JSON checkpoint store that persists checkpoint data and index
 /// information to disk using JSON files.
@@ -28,6 +31,8 @@ public sealed class FileSystemJsonCheckpointStore : JsonCheckpointStore, IDispos
    internal DirectoryInfo Directory { get; }
    internal HashSet<CheckpointInfo> CheckpointIndex { get; }

+    private static JsonTypeInfo<CheckpointFileIndexEntry> EntryTypeInfo => WorkflowsJsonUtilities.JsonContext.Default.CheckpointFileIndexEntry;
+
    /// <summary>
    /// Initializes a new instance of the <see cref="FileSystemJsonCheckpointStore"/> class that uses the specified directory
    /// </summary>
@@ -64,9 +69,11 @@ public sealed class FileSystemJsonCheckpointStore : JsonCheckpointStore, IDispos
            using StreamReader reader = new(this._indexFile, encoding: Encoding.UTF8, detectEncodingFromByteOrderMarks: false, BufferSize, leaveOpen: true);
            while (reader.ReadLine() is string line)
            {
-                if (JsonSerializer.Deserialize(line, KeyTypeInfo) is { } info)
+                if (JsonSerializer.Deserialize(line, EntryTypeInfo) is { } entry)
                {
-                    this.CheckpointIndex.Add(info);
+                    // We never actually use the file names from the index entries since they can be derived from the CheckpointInfo, but it is useful to
+                    // have the UrlEncoded file names in the index file for human readability
+                    this.CheckpointIndex.Add(entry.CheckpointInfo);
                }
            }
        }
@@ -93,8 +100,14 @@ public sealed class FileSystemJsonCheckpointStore : JsonCheckpointStore, IDispos
        }
    }

-    private string GetFileNameForCheckpoint(string sessionId, CheckpointInfo key)
-        => Path.Combine(this.Directory.FullName, $"{sessionId}_{key.CheckpointId}.json");
+    internal string GetFileNameForCheckpoint(string sessionId, CheckpointInfo key)
+    {
+        string protoPath = $"{sessionId}_{key.CheckpointId}.json";
+
+        // Escape the protoPath to ensure it is a valid file name, especially if sessionId or CheckpointId contain path separators, etc.
+        return Uri.EscapeDataString(protoPath) // This takes care of most of the invalid path characters
+                  .Replace(".", "%2E");        // This takes care of escaping the root folder, since EscapeDataString does not escape dots
+    }

    private CheckpointInfo GetUnusedCheckpointInfo(string sessionId)
    {
@@ -116,13 +129,16 @@ public sealed class FileSystemJsonCheckpointStore : JsonCheckpointStore, IDispos

        CheckpointInfo key = this.GetUnusedCheckpointInfo(sessionId);
        string fileName = this.GetFileNameForCheckpoint(sessionId, key);
+        string filePath = Path.Combine(this.Directory.FullName, fileName);
+
        try
        {
-            using Stream checkpointStream = File.Open(fileName, FileMode.Create, FileAccess.Write, FileShare.None);
+            using Stream checkpointStream = File.Open(filePath, FileMode.Create, FileAccess.Write, FileShare.None);
            using Utf8JsonWriter jsonWriter = new(checkpointStream, new JsonWriterOptions() { Indented = false });
            value.WriteTo(jsonWriter);

-            JsonSerializer.Serialize(this._indexFile!, key, KeyTypeInfo);
+            CheckpointFileIndexEntry entry = new(key, fileName);
+            JsonSerializer.Serialize(this._indexFile!, entry, EntryTypeInfo);
            byte[] bytes = Encoding.UTF8.GetBytes(Environment.NewLine);
            await this._indexFile!.WriteAsync(bytes, 0, bytes.Length, CancellationToken.None).ConfigureAwait(false);
            await this._indexFile!.FlushAsync(CancellationToken.None).ConfigureAwait(false);
@@ -136,7 +152,7 @@ public sealed class FileSystemJsonCheckpointStore : JsonCheckpointStore, IDispos
            try
            {
                // try to clean up after ourselves
-                File.Delete(fileName);
+                File.Delete(filePath);
            }
            catch { }

@@ -149,6 +165,7 @@ public sealed class FileSystemJsonCheckpointStore : JsonCheckpointStore, IDispos
    {
        this.CheckDisposed();
        string fileName = this.GetFileNameForCheckpoint(sessionId, key);
+        string filePath = Path.Combine(this.Directory.FullName, fileName);

        if (!this.CheckpointIndex.Contains(key) ||
            !File.Exists(fileName))
@@ -156,7 +173,7 @@ public sealed class FileSystemJsonCheckpointStore : JsonCheckpointStore, IDispos
            throw new KeyNotFoundException($"Checkpoint '{key.CheckpointId}' not found in store at '{this.Directory.FullName}'.");
        }

-        using FileStream checkpointFileStream = File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
+        using FileStream checkpointFileStream = File.Open(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
        using JsonDocument document = await JsonDocument.ParseAsync(checkpointFileStream).ConfigureAwait(false);

        return document.RootElement.Clone();
@@ -3,9 +3,9 @@
 namespace Microsoft.Agents.AI.Workflows;

 /// <summary>
-/// Provides extensions methods for creating <see cref="Configured{TSubject}"/> objects
+/// Provides extension methods for creating <see cref="Configured{TSubject}"/> objects
 /// </summary>
-public static class ConfigurationExtensions
+internal static class ConfigurationExtensions
 {
    /// <summary>
    /// Creates a new configuration that treats the subject as its base type, allowing configuration to be applied at
@@ -8,7 +8,7 @@ namespace Microsoft.Agents.AI.Workflows;
 /// <summary>
 /// Provides methods for creating <see cref="Configured{TSubject}"/> instances.
 /// </summary>
-public static class Configured
+internal static class Configured
 {
    /// <summary>
    /// Creates a <see cref="Configured{TSubject}"/> instance from an existing subject instance.
@@ -50,10 +50,10 @@ public static class Configured
 /// A representation of a preconfigured, lazy-instantiatable instance of <typeparamref name="TSubject"/>.
 /// </summary>
 /// <typeparam name="TSubject">The type of the preconfigured subject.</typeparam>
-/// <param name="factoryAsync">A factory to intantiate the subject when desired.</param>
+/// <param name="factoryAsync">A factory to instantiate the subject when desired.</param>
 /// <param name="id">The unique identifier for the configured subject.</param>
 /// <param name="raw"></param>
-public class Configured<TSubject>(Func<Config, string, ValueTask<TSubject>> factoryAsync, string id, object? raw = null)
+internal class Configured<TSubject>(Func<ExecutorConfig, string, ValueTask<TSubject>> factoryAsync, string id, object? raw = null)
 {
    /// <summary>
    /// Gets the raw representation of the configured object, if any.
@@ -66,14 +66,14 @@ public class Configured<TSubject>(Func<Config, string, ValueTask<TSubject>> fact
    public string Id => id;

    /// <summary>
-    /// Gets the factory function to create an instance of <typeparamref name="TSubject"/> given a <see cref="Config"/>.
+    /// Gets the factory function to create an instance of <typeparamref name="TSubject"/> given a <see cref="ExecutorConfig"/>.
    /// </summary>
-    public Func<Config, string, ValueTask<TSubject>> FactoryAsync => factoryAsync;
+    public Func<ExecutorConfig, string, ValueTask<TSubject>> FactoryAsync => factoryAsync;

    /// <summary>
    /// The configuration for this configured instance.
    /// </summary>
-    public Config Configuration => new(this.Id);
+    public ExecutorConfig Configuration => new(this.Id);

    /// <summary>
    /// Gets a "partially" applied factory function that only requires no parameters to create an instance of
@@ -87,11 +87,11 @@ public class Configured<TSubject>(Func<Config, string, ValueTask<TSubject>> fact
 /// </summary>
 /// <typeparam name="TSubject">The type of the preconfigured subject.</typeparam>
 /// <typeparam name="TOptions">The type of configuration options for the preconfigured subject.</typeparam>
-/// <param name="factoryAsync">A factory to intantiate the subject when desired.</param>
+/// <param name="factoryAsync">A factory to instantiate the subject when desired.</param>
 /// <param name="id">The unique identifier for the configured subject.</param>
 /// <param name="options">Additional configuration options for the subject.</param>
 /// <param name="raw"></param>
-public class Configured<TSubject, TOptions>(Func<Config<TOptions>, string, ValueTask<TSubject>> factoryAsync, string id, TOptions? options = default, object? raw = null)
+internal class Configured<TSubject, TOptions>(Func<ExecutorConfig<TOptions>, string, ValueTask<TSubject>> factoryAsync, string id, TOptions? options = default, object? raw = null)
 {
    /// <summary>
    /// The raw representation of the configured object, if any.
@@ -109,14 +109,14 @@ public class Configured<TSubject, TOptions>(Func<Config<TOptions>, string, Value
    public TOptions? Options => options;

    /// <summary>
-    /// Gets the factory function to create an instance of <typeparamref name="TSubject"/> given a <see cref="Config{TOptions}"/>.
+    /// Gets the factory function to create an instance of <typeparamref name="TSubject"/> given a <see cref="ExecutorConfig{TOptions}"/>.
    /// </summary>
-    public Func<Config<TOptions>, string, ValueTask<TSubject>> FactoryAsync => factoryAsync;
+    public Func<ExecutorConfig<TOptions>, string, ValueTask<TSubject>> FactoryAsync => factoryAsync;

    /// <summary>
    /// The configuration for this configured instance.
    /// </summary>
-    public Config<TOptions> Configuration => new(this.Id, this.Options);
+    public ExecutorConfig<TOptions> Configuration => new(this.Id, this.Options);

    /// <summary>
    /// Gets a "partially" applied factory function that only requires no parameters to create an instance of
@@ -124,11 +124,11 @@ public class Configured<TSubject, TOptions>(Func<Config<TOptions>, string, Value
    /// </summary>
    internal Func<string, ValueTask<TSubject>> BoundFactoryAsync => (sessionId) => this.CreateValidatingMemoizedFactory()(this.Configuration, sessionId);

-    private Func<Config, string, ValueTask<TSubject>> CreateValidatingMemoizedFactory()
+    private Func<ExecutorConfig, string, ValueTask<TSubject>> CreateValidatingMemoizedFactory()
    {
        return FactoryAsync;

-        async ValueTask<TSubject> FactoryAsync(Config configuration, string sessionId)
+        async ValueTask<TSubject> FactoryAsync(ExecutorConfig configuration, string sessionId)
        {
            if (this.Id != configuration.Id)
            {
@@ -53,6 +53,9 @@ internal sealed class AsyncRunHandle : ICheckpointingHandle, IAsyncDisposable
    public ValueTask<RunStatus> GetStatusAsync(CancellationToken cancellationToken = default)
        => this._eventStream.GetStatusAsync(cancellationToken);

+    internal bool TryGetResponsePortExecutorId(string portId, out string? executorId)
+        => this._stepRunner.TryGetResponsePortExecutorId(portId, out executorId);
+
    public async IAsyncEnumerable<WorkflowEvent> TakeEventStreamAsync(bool blockOnPendingRequest, [EnumeratorCancellation] CancellationToken cancellationToken = default)
    {
        //Debug.Assert(breakOnHalt);
@@ -3,6 +3,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -95,6 +96,18 @@ internal sealed class EdgeMap
        return portRunner.ChaseEdgeAsync(new MessageEnvelope(response, ExecutorIdentity.None), this._stepTracer, cancellationToken);
    }

+    internal bool TryGetResponsePortExecutorId(string portId, [NotNullWhen(true)] out string? executorId)
+    {
+        if (this._portEdgeRunners.TryGetValue(portId, out ResponseEdgeRunner? portRunner))
+        {
+            executorId = portRunner.ExecutorId;
+            return true;
+        }
+
+        executorId = null;
+        return false;
+    }
+
    internal async ValueTask<Dictionary<EdgeId, PortableValue>> ExportStateAsync()
    {
        Dictionary<EdgeId, PortableValue> exportedStates = [];
@@ -19,6 +19,7 @@ internal interface ISuperStepRunner
    bool HasUnprocessedMessages { get; }

    ValueTask EnqueueResponseAsync(ExternalResponse response, CancellationToken cancellationToken = default);
+    bool TryGetResponsePortExecutorId(string portId, out string? executorId);

    ValueTask<bool> IsValidInputTypeAsync<T>(CancellationToken cancellationToken = default);
    ValueTask<bool> EnqueueMessageAsync<T>(T message, CancellationToken cancellationToken = default);
@@ -106,8 +106,7 @@ internal sealed class StateManager
        if (typeof(T) == typeof(object))
        {
            // Reading as object will break across serialize/deserialize boundaries, e.g. checkpointing, distributed runtime, etc.
-            // Disabled pending upstream updates for this change; see https://github.com/microsoft/agent-framework/issues/1369
-            //throw new NotSupportedException("Reading state as 'object' is not supported. Use 'PortableValue' instead for variants.");
+            throw new NotSupportedException("Reading state as 'object' is not supported. Use 'PortableValue' instead for variants.");
        }

        Throw.IfNullOrEmpty(key);
@@ -113,7 +113,7 @@ public static class ExecutorBindingExtensions
    /// <param name="id">An id for the executor to be instantiated.</param>
    /// <param name="options">An optional parameter specifying the options.</param>
    /// <returns>An <see cref="ExecutorBinding"/> instance that resolves to the result of the factory call when messages get sent to it.</returns>
-    public static ExecutorBinding BindExecutor<TExecutor, TOptions>(this Func<Config<TOptions>, string, ValueTask<TExecutor>> factoryAsync, string id, TOptions? options = null)
+    public static ExecutorBinding BindExecutor<TExecutor, TOptions>(this Func<ExecutorConfig<TOptions>, string, ValueTask<TExecutor>> factoryAsync, string id, TOptions? options = null)
        where TExecutor : Executor
        where TOptions : ExecutorOptions
    {
@@ -139,7 +139,7 @@ public static class ExecutorBindingExtensions
    /// <returns>An <see cref="ExecutorBinding"/> instance that resolves to the result of the factory call when messages get sent to it.</returns>
    [Obsolete("Use BindExecutor() instead")]
    [EditorBrowsable(EditorBrowsableState.Never)]
-    public static ExecutorBinding ConfigureFactory<TExecutor, TOptions>(this Func<Config<TOptions>, string, ValueTask<TExecutor>> factoryAsync, string id, TOptions? options = null)
+    public static ExecutorBinding ConfigureFactory<TExecutor, TOptions>(this Func<ExecutorConfig<TOptions>, string, ValueTask<TExecutor>> factoryAsync, string id, TOptions? options = null)
        where TExecutor : Executor
        where TOptions : ExecutorOptions
        => factoryAsync.BindExecutor(id, options);
@@ -6,7 +6,7 @@ namespace Microsoft.Agents.AI.Workflows;
 /// Represents a configuration for an object with a string identifier. For example, <see cref="IIdentified"/> object.
 /// </summary>
 /// <param name="id">A unique identifier for the configurable object.</param>
-public class Config(string id)
+public class ExecutorConfig(string id)
 {
    /// <summary>
    /// Gets a unique identifier for the configurable object.
@@ -23,7 +23,7 @@ public class Config(string id)
 /// <typeparam name="TOptions">The type of options for the configurable object.</typeparam>
 /// <param name="id">A unique identifier for the configurable object.</param>
 /// <param name="options">The options for the configurable object.</param>
-public class Config<TOptions>(string id, TOptions? options = default) : Config(id)
+public class ExecutorConfig<TOptions>(string id, TOptions? options = default) : ExecutorConfig(id)
 {
    /// <summary>
    /// Gets the options for the configured object.
@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.

+using System;
 using System.Collections.Generic;
 using System.Linq;
 using Microsoft.Agents.AI.Workflows.Specialized;
@@ -8,22 +9,42 @@ using Microsoft.Shared.Diagnostics;

 namespace Microsoft.Agents.AI.Workflows;

+/// <inheritdoc/>
+[Obsolete("Prefer HandoffWorkflowBuilder (no 's') instead, which has the same API but the preferred name. This will be removed in a future release before GA.")]
+public sealed class HandoffsWorkflowBuilder(AIAgent initialAgent) : HandoffWorkflowBuilderCore<HandoffsWorkflowBuilder>(initialAgent)
+{
+}
+
+/// <inheritdoc/>
+public sealed class HandoffWorkflowBuilder(AIAgent initialAgent) : HandoffWorkflowBuilderCore<HandoffWorkflowBuilder>(initialAgent)
+{
+}
+
 /// <summary>
 /// Provides a builder for specifying the handoff relationships between agents and building the resulting workflow.
 /// </summary>
-public sealed class HandoffsWorkflowBuilder
+public class HandoffWorkflowBuilderCore<TBuilder> where TBuilder : HandoffWorkflowBuilderCore<TBuilder>
 {
-    internal const string FunctionPrefix = "handoff_to_";
+    /// <summary>
+    /// The prefix for function calls that trigger handoffs to other agents; the full name is then `{FunctionPrefix}&lt;agent_id&gt;`,
+    /// where `&lt;agent_id&gt;` is the ID of the target agent to hand off to.
+    /// </summary>
+    public const string FunctionPrefix = "handoff_to_";
+
    private readonly AIAgent _initialAgent;
    private readonly Dictionary<AIAgent, HashSet<HandoffTarget>> _targets = [];
    private readonly HashSet<AIAgent> _allAgents = new(AIAgentIDEqualityComparer.Instance);
+
+    private bool _emitAgentResponseEvents;
+    private bool _emitAgentResponseUpdateEvents;
    private HandoffToolCallFilteringBehavior _toolCallFilteringBehavior = HandoffToolCallFilteringBehavior.HandoffOnly;
+    private bool _returnToPrevious;

    /// <summary>
    /// Initializes a new instance of the <see cref="HandoffsWorkflowBuilder"/> class with no handoff relationships.
    /// </summary>
    /// <param name="initialAgent">The first agent to be invoked (prior to any handoff).</param>
-    internal HandoffsWorkflowBuilder(AIAgent initialAgent)
+    internal HandoffWorkflowBuilderCore(AIAgent initialAgent)
    {
        this._initialAgent = initialAgent;
        this._allAgents.Add(initialAgent);
@@ -47,14 +68,41 @@ public sealed class HandoffsWorkflowBuilder
              """;

    /// <summary>
-    /// Sets additional instructions to provide to an agent that has handoffs about how and when to
-    /// perform them.
+    /// Sets instructions to provide to each agent that has handoffs about how and when to perform them.
    /// </summary>
+    /// <remarks>
+    /// In the vast majority of cases, the <see cref="DefaultHandoffInstructions"/> will be sufficient, and there will be no need to customize.
+    /// If you do provide alternate instructions, remember to explain the mechanics of the handoff function tool call, using see
+    /// <see cref="FunctionPrefix"/> constant.
+    /// </remarks>
    /// <param name="instructions">The instructions to provide, or <see langword="null"/> to restore the default instructions.</param>
-    public HandoffsWorkflowBuilder WithHandoffInstructions(string? instructions)
+    public TBuilder WithHandoffInstructions(string? instructions)
    {
        this.HandoffInstructions = instructions ?? DefaultHandoffInstructions;
-        return this;
+        return (TBuilder)this;
+    }
+
+    /// <summary>
+    /// Sets a value indicating whether agent streaming update events should be emitted during execution.
+    /// If <see langword="null"/>, the value will be taken from the <see cref="TurnToken"/>
+    /// </summary>
+    /// <param name="emitAgentResponseUpdateEvents"></param>
+    /// <returns></returns>
+    public TBuilder EmitAgentResponseUpdateEvents(bool emitAgentResponseUpdateEvents = true)
+    {
+        this._emitAgentResponseUpdateEvents = emitAgentResponseUpdateEvents;
+        return (TBuilder)this;
+    }
+
+    /// <summary>
+    /// Sets a value indicating whether aggregated agent response events should be emitted during execution.
+    /// </summary>
+    /// <param name="emitAgentResponseEvents"></param>
+    /// <returns></returns>
+    public TBuilder EmitAgentResponseEvents(bool emitAgentResponseEvents = true)
+    {
+        this._emitAgentResponseEvents = emitAgentResponseEvents;
+        return (TBuilder)this;
    }

    /// <summary>
@@ -62,10 +110,21 @@ public sealed class HandoffsWorkflowBuilder
    /// <see cref="ChatMessage"/>s flowing through the handoff workflow. Defaults to <see cref="HandoffToolCallFilteringBehavior.HandoffOnly"/>.
    /// </summary>
    /// <param name="behavior">The filtering behavior to apply.</param>
-    public HandoffsWorkflowBuilder WithToolCallFilteringBehavior(HandoffToolCallFilteringBehavior behavior)
+    public TBuilder WithToolCallFilteringBehavior(HandoffToolCallFilteringBehavior behavior)
    {
        this._toolCallFilteringBehavior = behavior;
-        return this;
+        return (TBuilder)this;
+    }
+
+    /// <summary>
+    /// Configures the workflow so that subsequent user turns route directly back to the specialist agent
+    /// that handled the previous turn, rather than always routing through the initial (coordinator) agent.
+    /// </summary>
+    /// <returns>The updated <see cref="HandoffsWorkflowBuilder"/> instance.</returns>
+    public TBuilder EnableReturnToPrevious()
+    {
+        this._returnToPrevious = true;
+        return (TBuilder)this;
    }

    /// <summary>
@@ -75,7 +134,7 @@ public sealed class HandoffsWorkflowBuilder
    /// <param name="to">The target agents to add as handoff targets for the source agent.</param>
    /// <returns>The updated <see cref="HandoffsWorkflowBuilder"/> instance.</returns>
    /// <remarks>The handoff reason for each target in <paramref name="to"/> is derived from that agent's description or name.</remarks>
-    public HandoffsWorkflowBuilder WithHandoffs(AIAgent from, IEnumerable<AIAgent> to)
+    public TBuilder WithHandoffs(AIAgent from, IEnumerable<AIAgent> to)
    {
        Throw.IfNull(from);
        Throw.IfNull(to);
@@ -90,7 +149,7 @@ public sealed class HandoffsWorkflowBuilder
            this.WithHandoff(from, target);
        }

-        return this;
+        return (TBuilder)this;
    }

    /// <summary>
@@ -103,7 +162,7 @@ public sealed class HandoffsWorkflowBuilder
    /// If <see langword="null"/>, the reason is derived from <paramref name="to"/>'s description or name.
    /// </param>
    /// <returns>The updated <see cref="HandoffsWorkflowBuilder"/> instance.</returns>
-    public HandoffsWorkflowBuilder WithHandoffs(IEnumerable<AIAgent> from, AIAgent to, string? handoffReason = null)
+    public TBuilder WithHandoffs(IEnumerable<AIAgent> from, AIAgent to, string? handoffReason = null)
    {
        Throw.IfNull(from);
        Throw.IfNull(to);
@@ -118,7 +177,7 @@ public sealed class HandoffsWorkflowBuilder
            this.WithHandoff(source, to, handoffReason);
        }

-        return this;
+        return (TBuilder)this;
    }

    /// <summary>
@@ -131,7 +190,7 @@ public sealed class HandoffsWorkflowBuilder
    /// If <see langword="null"/>, the reason is derived from <paramref name="to"/>'s description or name.
    /// </param>
    /// <returns>The updated <see cref="HandoffsWorkflowBuilder"/> instance.</returns>
-    public HandoffsWorkflowBuilder WithHandoff(AIAgent from, AIAgent to, string? handoffReason = null)
+    public TBuilder WithHandoff(AIAgent from, AIAgent to, string? handoffReason = null)
    {
        Throw.IfNull(from);
        Throw.IfNull(to);
@@ -161,7 +220,7 @@ public sealed class HandoffsWorkflowBuilder
            Throw.InvalidOperationException($"A handoff from agent '{from.Name ?? from.Id}' to agent '{to.Name ?? to.Id}' has already been registered.");
        }

-        return this;
+        return (TBuilder)this;
    }

    /// <summary>
@@ -171,17 +230,40 @@ public sealed class HandoffsWorkflowBuilder
    /// <returns>The workflow built based on the handoffs in the builder.</returns>
    public Workflow Build()
    {
-        HandoffsStartExecutor start = new();
-        HandoffsEndExecutor end = new();
+        HandoffsStartExecutor start = new(this._returnToPrevious);
+        HandoffsEndExecutor end = new(this._returnToPrevious);
        WorkflowBuilder builder = new(start);

-        HandoffAgentExecutorOptions options = new(this.HandoffInstructions, this._toolCallFilteringBehavior);
+        HandoffAgentExecutorOptions options = new(this.HandoffInstructions,
+                                                  this._emitAgentResponseEvents,
+                                                  this._emitAgentResponseUpdateEvents,
+                                                  this._toolCallFilteringBehavior);

-        // Create an AgentExecutor for each again.
+        // Create an AgentExecutor for each agent.
        Dictionary<string, HandoffAgentExecutor> executors = this._allAgents.ToDictionary(a => a.Id, a => new HandoffAgentExecutor(a, options));

-        // Connect the start executor to the initial agent.
-        builder.AddEdge(start, executors[this._initialAgent.Id]);
+        // Connect the start executor to the initial agent (or use dynamic routing when ReturnToPrevious is enabled).
+        if (this._returnToPrevious)
+        {
+            string initialAgentId = this._initialAgent.Id;
+            builder.AddSwitch(start, sb =>
+            {
+                foreach (var agent in this._allAgents)
+                {
+                    if (agent.Id != initialAgentId)
+                    {
+                        string agentId = agent.Id;
+                        sb.AddCase<HandoffState>(state => state?.CurrentAgentId == agentId, executors[agentId]);
+                    }
+                }
+
+                sb.WithDefault(executors[initialAgentId]);
+            });
+        }
+        else
+        {
+            builder.AddEdge(start, executors[this._initialAgent.Id]);
+        }

        // Initialize each executor with its handoff targets to the other executors.
        foreach (var agent in this._allAgents)
@@ -160,6 +160,8 @@ internal sealed class InProcessRunner : ISuperStepRunner, ICheckpointingHandle

    bool ISuperStepRunner.HasUnservicedRequests => this.RunContext.HasUnservicedRequests;
    bool ISuperStepRunner.HasUnprocessedMessages => this.RunContext.NextStepHasActions;
+    bool ISuperStepRunner.TryGetResponsePortExecutorId(string portId, out string? executorId)
+        => this.RunContext.TryGetResponsePortExecutorId(portId, out executorId);

    public bool IsCheckpointingEnabled => this.RunContext.IsCheckpointingEnabled;

@@ -296,6 +296,9 @@ internal sealed class InProcessRunnerContext : IRunnerContext
        return this._externalRequests.TryRemove(requestId, out _);
    }

+    internal bool TryGetResponsePortExecutorId(string portId, [NotNullWhen(true)] out string? executorId)
+        => this._edgeMap.TryGetResponsePortExecutorId(portId, out executorId);
+
    private IEventSink OutgoingEvents { get; }

    internal StateManager StateManager { get; } = new();
@@ -12,6 +12,15 @@ namespace Microsoft.Agents.AI.Workflows.Specialized;

 internal record AIAgentHostState(JsonElement? ThreadState, bool? CurrentTurnEmitEvents);

+internal static class TurnExtensions
+{
+    public static bool ShouldEmitStreamingEvents(this TurnToken token, bool? agentSetting)
+        => token.EmitEvents ?? agentSetting ?? false;
+
+    public static bool ShouldEmitStreamingEvents(bool? turnTokenSetting, bool? agentSetting)
+        => turnTokenSetting ?? agentSetting ?? false;
+}
+
 internal sealed class AIAgentHostExecutor : ChatProtocolExecutor
 {
    private readonly AIAgent _agent;
@@ -68,10 +77,17 @@ internal sealed class AIAgentHostExecutor : ChatProtocolExecutor
            throw new InvalidOperationException($"No pending ToolApprovalRequest found with id '{response.RequestId}'.");
        }

-        List<ChatMessage> implicitTurnMessages = [new ChatMessage(ChatRole.User, [response])];
+        // Merge the external response with any already-buffered regular messages so mixed-content
+        // resumes can be processed in one invocation.
+        return this.ProcessTurnMessagesAsync(async (pendingMessages, ctx, ct) =>
+        {
+            pendingMessages.Add(new ChatMessage(ChatRole.User, [response]));

-        // ContinueTurnAsync owns failing to emit a TurnToken if this response does not clear up all remaining outstanding requests.
-        return this.ContinueTurnAsync(implicitTurnMessages, context, this._currentTurnEmitEvents ?? false, cancellationToken);
+            await this.ContinueTurnAsync(pendingMessages, ctx, this._currentTurnEmitEvents ?? false, ct).ConfigureAwait(false);
+
+            // Clear the buffered turn messages because they were consumed by ContinueTurnAsync.
+            return null;
+        }, context, cancellationToken);
    }

    private ValueTask HandleFunctionResultAsync(
@@ -84,12 +100,18 @@ internal sealed class AIAgentHostExecutor : ChatProtocolExecutor
            throw new InvalidOperationException($"No pending FunctionCall found with id '{result.CallId}'.");
        }

-        List<ChatMessage> implicitTurnMessages = [new ChatMessage(ChatRole.Tool, [result])];
-        return this.ContinueTurnAsync(implicitTurnMessages, context, this._currentTurnEmitEvents ?? false, cancellationToken);
-    }
+        // Merge the external response with any already-buffered regular messages so mixed-content
+        // resumes can be processed in one invocation.
+        return this.ProcessTurnMessagesAsync(async (pendingMessages, ctx, ct) =>
+        {
+            pendingMessages.Add(new ChatMessage(ChatRole.Tool, [result]));

-    public bool ShouldEmitStreamingEvents(bool? emitEvents)
-        => emitEvents ?? this._options.EmitAgentUpdateEvents ?? false;
+            await this.ContinueTurnAsync(pendingMessages, ctx, this._currentTurnEmitEvents ?? false, ct).ConfigureAwait(false);
+
+            // Clear the buffered turn messages because they were consumed by ContinueTurnAsync.
+            return null;
+        }, context, cancellationToken);
+    }

    private async ValueTask<AgentSession> EnsureSessionAsync(IWorkflowContext context, CancellationToken cancellationToken) =>
        this._session ??= await this._agent.CreateSessionAsync(cancellationToken).ConfigureAwait(false);
@@ -159,7 +181,10 @@ internal sealed class AIAgentHostExecutor : ChatProtocolExecutor
    }

    protected override ValueTask TakeTurnAsync(List<ChatMessage> messages, IWorkflowContext context, bool? emitEvents, CancellationToken cancellationToken = default)
-        => this.ContinueTurnAsync(messages, context, this.ShouldEmitStreamingEvents(emitEvents), cancellationToken);
+        => this.ContinueTurnAsync(messages,
+                                  context,
+                                  TurnExtensions.ShouldEmitStreamingEvents(turnTokenSetting: emitEvents, this._options.EmitAgentUpdateEvents),
+                                  cancellationToken);

    private async ValueTask<AgentResponse> InvokeAgentAsync(IEnumerable<ChatMessage> messages, IWorkflowContext context, bool emitEvents, CancellationToken cancellationToken = default)
    {
@@ -198,7 +223,7 @@ internal sealed class AIAgentHostExecutor : ChatProtocolExecutor
            ExtractUnservicedRequests(response.Messages.SelectMany(message => message.Contents));
        }

-        if (this._options.EmitAgentResponseEvents == true)
+        if (this._options.EmitAgentResponseEvents)
        {
            await context.YieldOutputAsync(response, cancellationToken).ConfigureAwait(false);
        }
@@ -16,10 +16,12 @@ internal sealed class AIContentExternalHandler<TRequestContent, TResponseContent
    where TResponseContent : AIContent
 {
    private readonly PortBinding? _portBinding;
+    private readonly string _portId;
    private ConcurrentDictionary<string, TRequestContent> _pendingRequests = new();

    public AIContentExternalHandler(ref ProtocolBuilder protocolBuilder, string portId, bool intercepted, Func<TResponseContent, IWorkflowContext, CancellationToken, ValueTask> handler)
    {
+        this._portId = portId;
        PortBinding? portBinding = null;
        protocolBuilder = protocolBuilder.ConfigureRoutes(routeBuilder => ConfigureRoutes(routeBuilder, out portBinding));
        this._portBinding = portBinding;
@@ -58,12 +60,14 @@ internal sealed class AIContentExternalHandler<TRequestContent, TResponseContent
    {
        if (!this._pendingRequests.TryAdd(id, requestContent))
        {
-            throw new InvalidOperationException($"A pending request with ID '{id}' already exists.");
+            // Request is already pending; treat as an idempotent re-emission.
+            // Do not repost to the sink because request IDs must remain unique while pending.
+            return default;
        }

        return this.IsIntercepted
             ? context.SendMessageAsync(requestContent, cancellationToken: cancellationToken)
-             : this._portBinding.PostRequestAsync(requestContent, id, cancellationToken);
+             : this._portBinding.PostRequestAsync(requestContent, this.CreateExternalRequestId(id), cancellationToken);
    }

    public bool MarkRequestAsHandled(string id)
@@ -74,6 +78,8 @@ internal sealed class AIContentExternalHandler<TRequestContent, TResponseContent
    [MemberNotNullWhen(false, nameof(_portBinding))]
    private bool IsIntercepted => this._portBinding == null;

+    private string CreateExternalRequestId(string requestId) => $"{this._portId.Length}:{this._portId}:{requestId}";
+
    private static string MakeKey(string id) => $"{id}_PendingRequests";

    public async ValueTask OnCheckpointingAsync(string id, IWorkflowContext context, CancellationToken cancellationToken = default)
@@ -14,14 +14,20 @@ namespace Microsoft.Agents.AI.Workflows.Specialized;

 internal sealed class HandoffAgentExecutorOptions
 {
-    public HandoffAgentExecutorOptions(string? handoffInstructions, HandoffToolCallFilteringBehavior toolCallFilteringBehavior)
+    public HandoffAgentExecutorOptions(string? handoffInstructions, bool emitAgentResponseEvents, bool? emitAgentResponseUpdateEvents, HandoffToolCallFilteringBehavior toolCallFilteringBehavior)
    {
        this.HandoffInstructions = handoffInstructions;
+        this.EmitAgentResponseEvents = emitAgentResponseEvents;
+        this.EmitAgentResponseUpdateEvents = emitAgentResponseUpdateEvents;
        this.ToolCallFilteringBehavior = toolCallFilteringBehavior;
    }

    public string? HandoffInstructions { get; set; }

+    public bool EmitAgentResponseEvents { get; set; }
+
+    public bool? EmitAgentResponseUpdateEvents { get; set; }
+
    public HandoffToolCallFilteringBehavior ToolCallFilteringBehavior { get; set; } = HandoffToolCallFilteringBehavior.HandoffOnly;
 }

@@ -36,7 +42,7 @@ internal sealed class HandoffMessagesFilter

    internal static bool IsHandoffFunctionName(string name)
    {
-        return name.StartsWith(HandoffsWorkflowBuilder.FunctionPrefix, StringComparison.Ordinal);
+        return name.StartsWith(HandoffWorkflowBuilder.FunctionPrefix, StringComparison.Ordinal);
    }

    public IEnumerable<ChatMessage> FilterMessages(List<ChatMessage> messages)
@@ -167,6 +173,7 @@ internal sealed class HandoffAgentExecutor(

    private readonly AIAgent _agent = agent;
    private readonly HashSet<string> _handoffFunctionNames = [];
+    private readonly Dictionary<string, string> _handoffFunctionToAgentId = [];
    private ChatClientAgentRunOptions? _agentOptions;

    public void Initialize(
@@ -193,9 +200,10 @@ internal sealed class HandoffAgentExecutor(
                foreach (HandoffTarget handoff in handoffs)
                {
                    index++;
-                    var handoffFunc = AIFunctionFactory.CreateDeclaration($"{HandoffsWorkflowBuilder.FunctionPrefix}{index}", handoff.Reason, s_handoffSchema);
+                    var handoffFunc = AIFunctionFactory.CreateDeclaration($"{HandoffWorkflowBuilder.FunctionPrefix}{index}", handoff.Reason, s_handoffSchema);

                    this._handoffFunctionNames.Add(handoffFunc.Name);
+                    this._handoffFunctionToAgentId[handoffFunc.Name] = handoff.Target.Id;

                    this._agentOptions.ChatOptions.Tools.Add(handoffFunc);

@@ -250,16 +258,27 @@ internal sealed class HandoffAgentExecutor(
            }
        }

-        allMessages.AddRange(updates.ToAgentResponse().Messages);
+        AgentResponse agentResponse = updates.ToAgentResponse();
+
+        if (options.EmitAgentResponseEvents)
+        {
+            await context.YieldOutputAsync(agentResponse, cancellationToken).ConfigureAwait(false);
+        }
+
+        allMessages.AddRange(agentResponse.Messages);

        roleChanges.ResetUserToAssistantForChangedRoles();

-        return new(message.TurnToken, requestedHandoff, allMessages);
+        string currentAgentId = requestedHandoff is not null && this._handoffFunctionToAgentId.TryGetValue(requestedHandoff, out string? targetAgentId)
+            ? targetAgentId
+            : this._agent.Id;
+
+        return new(message.TurnToken, requestedHandoff, allMessages, currentAgentId);

        async Task AddUpdateAsync(AgentResponseUpdate update, CancellationToken cancellationToken)
        {
            updates.Add(update);
-            if (message.TurnToken.EmitEvents is true)
+            if (message.TurnToken.ShouldEmitStreamingEvents(options.EmitAgentResponseUpdateEvents))
            {
                await context.YieldOutputAsync(update, cancellationToken).ConfigureAwait(false);
            }
@@ -8,4 +8,5 @@ namespace Microsoft.Agents.AI.Workflows.Specialized;
 internal sealed record class HandoffState(
    TurnToken TurnToken,
    string? InvokedHandoff,
-    List<ChatMessage> Messages);
+    List<ChatMessage> Messages,
+    string? CurrentAgentId = null);
@@ -1,20 +1,35 @@
 // Copyright (c) Microsoft. All rights reserved.

 using System.Collections.Generic;
+using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.AI;

 namespace Microsoft.Agents.AI.Workflows.Specialized;

 /// <summary>Executor used at the end of a handoff workflow to raise a final completed event.</summary>
-internal sealed class HandoffsEndExecutor() : Executor(ExecutorId, declareCrossRunShareable: true), IResettableExecutor
+internal sealed class HandoffsEndExecutor(bool returnToPrevious) : Executor(ExecutorId, declareCrossRunShareable: true), IResettableExecutor
 {
    public const string ExecutorId = "HandoffEnd";

    protected override ProtocolBuilder ConfigureProtocol(ProtocolBuilder protocolBuilder) =>
        protocolBuilder.ConfigureRoutes(routeBuilder => routeBuilder.AddHandler<HandoffState>((handoff, context, cancellationToken) =>
-                                            context.YieldOutputAsync(handoff.Messages, cancellationToken)))
+                                            this.HandleAsync(handoff, context, cancellationToken)))
                       .YieldsOutput<List<ChatMessage>>();

+    private async ValueTask HandleAsync(HandoffState handoff, IWorkflowContext context, CancellationToken cancellationToken)
+    {
+        if (returnToPrevious)
+        {
+            await context.QueueStateUpdateAsync<string?>(HandoffConstants.CurrentAgentTrackerKey,
+                                                         handoff.CurrentAgentId,
+                                                         HandoffConstants.CurrentAgentTrackerScope,
+                                                         cancellationToken)
+                         .ConfigureAwait(false);
+        }
+
+        await context.YieldOutputAsync(handoff.Messages, cancellationToken).ConfigureAwait(false);
+    }
+
    public ValueTask ResetAsync() => default;
 }
@@ -7,8 +7,14 @@ using Microsoft.Extensions.AI;

 namespace Microsoft.Agents.AI.Workflows.Specialized;

+internal static class HandoffConstants
+{
+    internal const string CurrentAgentTrackerKey = "LastAgentId";
+    internal const string CurrentAgentTrackerScope = "HandoffOrchestration";
+}
+
 /// <summary>Executor used at the start of a handoffs workflow to accumulate messages and emit them as HandoffState upon receiving a turn token.</summary>
-internal sealed class HandoffsStartExecutor() : ChatProtocolExecutor(ExecutorId, DefaultOptions, declareCrossRunShareable: true), IResettableExecutor
+internal sealed class HandoffsStartExecutor(bool returnToPrevious) : ChatProtocolExecutor(ExecutorId, DefaultOptions, declareCrossRunShareable: true), IResettableExecutor
 {
    internal const string ExecutorId = "HandoffStart";

@@ -22,7 +28,25 @@ internal sealed class HandoffsStartExecutor() : ChatProtocolExecutor(ExecutorId,
        base.ConfigureProtocol(protocolBuilder).SendsMessage<HandoffState>();

    protected override ValueTask TakeTurnAsync(List<ChatMessage> messages, IWorkflowContext context, bool? emitEvents, CancellationToken cancellationToken = default)
-        => context.SendMessageAsync(new HandoffState(new(emitEvents), null, messages), cancellationToken: cancellationToken);
+    {
+        if (returnToPrevious)
+        {
+            return context.InvokeWithStateAsync(
+                async (string? currentAgentId, IWorkflowContext context, CancellationToken cancellationToken) =>
+                {
+                    HandoffState handoffState = new(new(emitEvents), null, messages, currentAgentId);
+                    await context.SendMessageAsync(handoffState, cancellationToken).ConfigureAwait(false);
+
+                    return currentAgentId;
+                },
+                HandoffConstants.CurrentAgentTrackerKey,
+                HandoffConstants.CurrentAgentTrackerScope,
+                cancellationToken);
+        }
+
+        HandoffState handoff = new(new(emitEvents), null, messages);
+        return context.SendMessageAsync(handoff, cancellationToken);
+    }

    public new ValueTask ResetAsync() => base.ResetAsync();
 }
@@ -60,6 +60,9 @@ public sealed class StreamingRun : CheckpointableRunBase, IAsyncDisposable
    internal ValueTask<bool> TrySendMessageUntypedAsync(object message, Type? declaredType = null)
        => this._runHandle.EnqueueMessageUntypedAsync(message, declaredType);

+    internal bool TryGetResponsePortExecutorId(string portId, out string? executorId)
+        => this._runHandle.TryGetResponsePortExecutorId(portId, out executorId);
+
    /// <summary>
    /// Asynchronously streams workflow events as they occur during workflow execution.
    /// </summary>
@@ -43,7 +43,7 @@ internal sealed class WorkflowChatHistoryProvider : ChatHistoryProvider
        => this._sessionState.GetOrInitializeState(session).Messages.AddRange(messages);

    protected override ValueTask<IEnumerable<ChatMessage>> ProvideChatHistoryAsync(InvokingContext context, CancellationToken cancellationToken = default)
-        => new(this._sessionState.GetOrInitializeState(context.Session).Messages);
+        => new(this._sessionState.GetOrInitializeState(context.Session).Messages.AsReadOnly());

    protected override ValueTask StoreChatHistoryAsync(InvokedContext context, CancellationToken cancellationToken = default)
    {
@@ -62,6 +62,12 @@ internal sealed class WorkflowChatHistoryProvider : ChatHistoryProvider
        }
    }

+    public IEnumerable<ChatMessage> GetAllMessages(AgentSession session)
+    {
+        var state = this._sessionState.GetOrInitializeState(session);
+        return state.Messages.AsReadOnly();
+    }
+
    public void UpdateBookmark(AgentSession session)
    {
        var state = this._sessionState.GetOrInitializeState(session);
@@ -119,13 +119,17 @@ internal sealed class WorkflowHostAgent : AIAgent
        MessageMerger merger = new();

        await foreach (AgentResponseUpdate update in workflowSession.InvokeStageAsync(cancellationToken)
-                                                                      .ConfigureAwait(false)
-                                                                      .WithCancellation(cancellationToken))
+                                                                     .ConfigureAwait(false)
+                                                                     .WithCancellation(cancellationToken))
        {
            merger.AddUpdate(update);
        }

-        return merger.ComputeMerged(workflowSession.LastResponseId!, this.Id, this.Name);
+        AgentResponse response = merger.ComputeMerged(workflowSession.LastResponseId!, this.Id, this.Name);
+        workflowSession.ChatHistoryProvider.AddMessages(workflowSession, response.Messages);
+        workflowSession.ChatHistoryProvider.UpdateBookmark(workflowSession);
+
+        return response;
    }

    protected override async
@@ -138,11 +142,18 @@ internal sealed class WorkflowHostAgent : AIAgent
        await this.ValidateWorkflowAsync().ConfigureAwait(false);

        WorkflowSession workflowSession = await this.UpdateSessionAsync(messages, session, cancellationToken).ConfigureAwait(false);
+        MessageMerger merger = new();
+
        await foreach (AgentResponseUpdate update in workflowSession.InvokeStageAsync(cancellationToken)
                                                                      .ConfigureAwait(false)
                                                                      .WithCancellation(cancellationToken))
        {
+            merger.AddUpdate(update);
            yield return update;
        }
+
+        AgentResponse response = merger.ComputeMerged(workflowSession.LastResponseId!, this.Id, this.Name);
+        workflowSession.ChatHistoryProvider.AddMessages(workflowSession, response.Messages);
+        workflowSession.ChatHistoryProvider.UpdateBookmark(workflowSession);
    }
 }
@@ -25,6 +25,25 @@ internal sealed class WorkflowSession : AgentSession

    private InMemoryCheckpointManager? _inMemoryCheckpointManager;

+    /// <summary>
+    /// Tracks pending external requests by their workflow-facing request ID.
+    /// This mapping enables converting incoming response content back to <see cref="ExternalResponse"/>
+    /// when resuming a workflow from a checkpoint.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Entries are added when a <see cref="RequestInfoEvent"/> is received during workflow execution,
+    /// and removed when a matching response is delivered via <see cref="SendMessagesWithResponseConversionAsync"/>.
+    /// </para>
+    /// <para>
+    /// The number of entries is bounded by the number of outstanding external requests in a single workflow run.
+    /// When a session is abandoned, all pending requests are released with the session object.
+    /// Request-level timeouts, if needed, should be implemented in the workflow definition itself
+    /// (e.g., using a timer racing against an external event).
+    /// </para>
+    /// </remarks>
+    private readonly Dictionary<string, ExternalRequest> _pendingRequests = [];
+
    internal static bool VerifyCheckpointingConfiguration(IWorkflowExecutionEnvironment executionEnvironment, [NotNullWhen(true)] out InProcessExecutionEnvironment? inProcEnv)
    {
        inProcEnv = null;
@@ -90,6 +109,7 @@ internal sealed class WorkflowSession : AgentSession

        this.LastCheckpoint = sessionState.LastCheckpoint;
        this.StateBag = sessionState.StateBag;
+        this._pendingRequests = sessionState.PendingRequests ?? [];
    }

    public CheckpointInfo? LastCheckpoint { get; set; }
@@ -101,7 +121,8 @@ internal sealed class WorkflowSession : AgentSession
            this.SessionId,
            this.LastCheckpoint,
            this._inMemoryCheckpointManager,
-            this.StateBag);
+            this.StateBag,
+            this._pendingRequests);

        return marshaller.Marshal(info);
    }
@@ -110,7 +131,7 @@ internal sealed class WorkflowSession : AgentSession
    {
        Throw.IfNullOrEmpty(parts);

-        AgentResponseUpdate update = new(ChatRole.Assistant, parts)
+        return new(ChatRole.Assistant, parts)
        {
            CreatedAt = DateTimeOffset.UtcNow,
            MessageId = Guid.NewGuid().ToString("N"),
@@ -118,30 +139,22 @@ internal sealed class WorkflowSession : AgentSession
            ResponseId = responseId,
            RawRepresentation = raw
        };
-
-        this.ChatHistoryProvider.AddMessages(this, update.ToChatMessage());
-
-        return update;
    }

    public AgentResponseUpdate CreateUpdate(string responseId, object raw, ChatMessage message)
    {
        Throw.IfNull(message);

-        AgentResponseUpdate update = new(message.Role, message.Contents)
+        return new(message.Role, message.Contents)
        {
            CreatedAt = message.CreatedAt ?? DateTimeOffset.UtcNow,
            MessageId = message.MessageId ?? Guid.NewGuid().ToString("N"),
            ResponseId = responseId,
            RawRepresentation = raw
        };
-
-        this.ChatHistoryProvider.AddMessages(this, update.ToChatMessage());
-
-        return update;
    }

-    private async ValueTask<StreamingRun> CreateOrResumeRunAsync(List<ChatMessage> messages, CancellationToken cancellationToken = default)
+    private async ValueTask<ResumeRunResult> CreateOrResumeRunAsync(List<ChatMessage> messages, CancellationToken cancellationToken = default)
    {
        // The workflow is validated to be a ChatProtocol workflow by the WorkflowHostAgent before creating the session,
        // and does not need to be checked again here.
@@ -154,109 +167,257 @@ internal sealed class WorkflowSession : AgentSession
                                               cancellationToken)
                            .ConfigureAwait(false);

-            await run.TrySendMessageAsync(messages).ConfigureAwait(false);
-            return run;
+            // Process messages: convert response content to ExternalResponse, send regular messages as-is
+            ResumeDispatchInfo dispatchInfo = await this.SendMessagesWithResponseConversionAsync(run, messages).ConfigureAwait(false);
+            return new ResumeRunResult(run, dispatchInfo);
        }

-        return await this._executionEnvironment
+        StreamingRun newRun = await this._executionEnvironment
                            .RunStreamingAsync(this._workflow,
                                         messages,
                                         this.SessionId,
                                         cancellationToken)
                            .ConfigureAwait(false);
+        return new ResumeRunResult(newRun);
    }

+    /// <summary>
+    /// Sends messages to the run, converting FunctionResultContent and UserInputResponseContent
+    /// to ExternalResponse when there's a matching pending request.
+    /// </summary>
+    /// <returns>
+    /// Structured information about how resume content was dispatched.
+    /// </returns>
+    private async ValueTask<ResumeDispatchInfo> SendMessagesWithResponseConversionAsync(StreamingRun run, List<ChatMessage> messages)
+    {
+        List<ChatMessage> regularMessages = [];
+        // Responses are deferred until after regular messages are queued so response handlers
+        // can merge buffered regular content in the same continuation turn.
+        List<(ExternalResponse Response, string RequestId)> externalResponses = [];
+        bool hasMatchedResponseForStartExecutor = false;
+
+        // Tracks content IDs already matched to pending requests within this invocation,
+        // preventing duplicate responses for the same ID from being sent to the workflow engine.
+        HashSet<string>? matchedContentIds = null;
+
+        foreach (ChatMessage message in messages)
+        {
+            List<AIContent> regularContents = [];
+
+            foreach (AIContent content in message.Contents)
+            {
+                string? contentId = GetResponseContentId(content);
+
+                // Skip duplicate response content for an already-matched content ID
+                if (contentId != null && matchedContentIds?.Contains(contentId) == true)
+                {
+                    continue;
+                }
+
+                if (contentId != null
+                    && this.TryGetPendingRequest(contentId) is ExternalRequest pendingRequest)
+                {
+                    // For intercepted/complex topologies the port may not be registered in the EdgeMap.
+                    // Treat unknown port as non-start-executor (conservative): TurnToken will still be sent.
+                    if (run.TryGetResponsePortExecutorId(pendingRequest.PortInfo.PortId, out string? responseExecutorId))
+                    {
+                        hasMatchedResponseForStartExecutor |= string.Equals(responseExecutorId, this._workflow.StartExecutorId, StringComparison.Ordinal);
+                    }
+
+                    AIContent normalizedResponseContent = NormalizeResponseContentForDelivery(content, pendingRequest);
+                    externalResponses.Add((pendingRequest.CreateResponse(normalizedResponseContent), pendingRequest.RequestId));
+                    (matchedContentIds ??= new(StringComparer.Ordinal)).Add(contentId);
+                }
+                else
+                {
+                    regularContents.Add(content);
+                }
+            }
+
+            if (regularContents.Count > 0)
+            {
+                ChatMessage cloned = message.Clone();
+                cloned.Contents = regularContents;
+                regularMessages.Add(cloned);
+            }
+        }
+
+        // Send regular messages first so response handlers can merge them with responses.
+        bool hasRegularMessages = regularMessages.Count > 0;
+        if (hasRegularMessages)
+        {
+            await run.TrySendMessageAsync(regularMessages).ConfigureAwait(false);
+        }
+
+        // Send external responses after regular messages.
+        bool hasMatchedExternalResponses = false;
+        foreach ((ExternalResponse response, string requestId) in externalResponses)
+        {
+            await run.SendResponseAsync(response).ConfigureAwait(false);
+            hasMatchedExternalResponses = true;
+            this.RemovePendingRequest(requestId);
+        }
+
+        return new ResumeDispatchInfo(
+            hasRegularMessages,
+            hasMatchedExternalResponses,
+            hasMatchedResponseForStartExecutor);
+    }
+
+    /// <summary>
+    /// Creates the workflow-facing request content surfaced in response updates.
+    /// </summary>
+    private static AIContent CreateRequestContentForDelivery(ExternalRequest request) => request switch
+    {
+        ExternalRequest externalRequest when externalRequest.TryGetDataAs(out FunctionCallContent? functionCallContent)
+            => CloneFunctionCallContent(functionCallContent, externalRequest.RequestId),
+        ExternalRequest externalRequest when externalRequest.TryGetDataAs(out ToolApprovalRequestContent? toolApprovalRequestContent)
+            => CloneToolApprovalRequestContent(toolApprovalRequestContent, externalRequest.RequestId),
+        ExternalRequest externalRequest
+            => externalRequest.ToFunctionCall(),
+    };
+
+    /// <summary>
+    /// Rewrites workflow-facing response content back to the original agent-owned content ID.
+    /// </summary>
+    private static AIContent NormalizeResponseContentForDelivery(AIContent content, ExternalRequest request) => content switch
+    {
+        FunctionResultContent functionResultContent when request.TryGetDataAs(out FunctionCallContent? functionCallContent)
+            => CloneFunctionResultContent(functionResultContent, functionCallContent.CallId),
+        ToolApprovalResponseContent toolApprovalResponseContent when request.TryGetDataAs(out ToolApprovalRequestContent? toolApprovalRequestContent)
+            => CloneToolApprovalResponseContent(toolApprovalResponseContent, toolApprovalRequestContent.RequestId),
+        _ => content,
+    };
+
+    /// <summary>
+    /// Gets the workflow-facing request ID from response content types.
+    /// </summary>
+    private static string? GetResponseContentId(AIContent content) => content switch
+    {
+        FunctionResultContent functionResultContent => functionResultContent.CallId,
+        ToolApprovalResponseContent toolApprovalResponseContent => toolApprovalResponseContent.RequestId,
+        _ => null
+    };
+
+    /// <summary>
+    /// Tries to get a pending request by workflow-facing request ID.
+    /// </summary>
+    private ExternalRequest? TryGetPendingRequest(string requestId) =>
+        this._pendingRequests.TryGetValue(requestId, out ExternalRequest? request) ? request : null;
+
+    /// <summary>
+    /// Adds a pending request indexed by workflow-facing request ID.
+    /// </summary>
+    private void AddPendingRequest(string requestId, ExternalRequest request) => this._pendingRequests[requestId] = request;
+
+    /// <summary>
+    /// Removes a pending request by workflow-facing request ID.
+    /// </summary>
+    private void RemovePendingRequest(string requestId) =>
+        this._pendingRequests.Remove(requestId);
+
    internal async
    IAsyncEnumerable<AgentResponseUpdate> InvokeStageAsync(
        [EnumeratorCancellation] CancellationToken cancellationToken = default)
    {
-        try
-        {
-            this.LastResponseId = Guid.NewGuid().ToString("N");
-            List<ChatMessage> messages = this.ChatHistoryProvider.GetFromBookmark(this).ToList();
+        this.LastResponseId = Guid.NewGuid().ToString("N");
+        List<ChatMessage> messages = this.ChatHistoryProvider.GetFromBookmark(this).ToList();

-#pragma warning disable CA2007 // Analyzer misfiring and not seeing .ConfigureAwait(false) below.
-            await using StreamingRun run =
-                await this.CreateOrResumeRunAsync(messages, cancellationToken).ConfigureAwait(false);
+        ResumeRunResult resumeResult =
+            await this.CreateOrResumeRunAsync(messages, cancellationToken).ConfigureAwait(false);
+
+#pragma warning disable CA2007 // Analyzer misfiring.
+        await using StreamingRun run = resumeResult.Run;
 #pragma warning restore CA2007

+        ResumeDispatchInfo dispatchInfo = resumeResult.DispatchInfo;
+
+        // Send a TurnToken to the start executor unless the only activity is an external
+        // response directed at the start executor itself (which self-emits a TurnToken via
+        // ContinueTurnAsync). Non-start executors (e.g., RequestInfoExecutor) do not emit
+        // TurnTokens after processing responses, so the session must always provide one.
+        bool shouldSendTurnToken =
+            !dispatchInfo.HasMatchedExternalResponses
+            || !dispatchInfo.HasMatchedResponseForStartExecutor;
+        if (shouldSendTurnToken)
+        {
            await run.TrySendMessageAsync(new TurnToken(emitEvents: true)).ConfigureAwait(false);
-            await foreach (WorkflowEvent evt in run.WatchStreamAsync(blockOnPendingRequest: false, cancellationToken)
+        }
+        await foreach (WorkflowEvent evt in run.WatchStreamAsync(blockOnPendingRequest: false, cancellationToken)
                                               .ConfigureAwait(false)
                                               .WithCancellation(cancellationToken))
-            {
-                switch (evt)
-                {
-                    case AgentResponseUpdateEvent agentUpdate:
-                        yield return agentUpdate.Update;
-                        break;
-
-                    case RequestInfoEvent requestInfo:
-                        FunctionCallContent fcContent = requestInfo.Request.ToFunctionCall();
-                        AgentResponseUpdate update = this.CreateUpdate(this.LastResponseId, evt, fcContent);
-                        yield return update;
-                        break;
-
-                    case WorkflowErrorEvent workflowError:
-                        Exception? exception = workflowError.Exception;
-                        if (exception is TargetInvocationException tie && tie.InnerException != null)
-                        {
-                            exception = tie.InnerException;
-                        }
-
-                        if (exception != null)
-                        {
-                            string message = this._includeExceptionDetails
-                                           ? exception.Message
-                                           : "An error occurred while executing the workflow.";
-
-                            ErrorContent errorContent = new(message);
-                            yield return this.CreateUpdate(this.LastResponseId, evt, errorContent);
-                        }
-
-                        break;
-
-                    case SuperStepCompletedEvent stepCompleted:
-                        this.LastCheckpoint = stepCompleted.CompletionInfo?.Checkpoint;
-                        goto default;
-
-                    case WorkflowOutputEvent output:
-                        IEnumerable<ChatMessage>? updateMessages = output.Data switch
-                        {
-                            IEnumerable<ChatMessage> chatMessages => chatMessages,
-                            ChatMessage chatMessage => [chatMessage],
-                            _ => null
-                        };
-
-                        if (!this._includeWorkflowOutputsInResponse || updateMessages == null)
-                        {
-                            goto default;
-                        }
-
-                        foreach (ChatMessage message in updateMessages)
-                        {
-                            yield return this.CreateUpdate(this.LastResponseId, evt, message);
-                        }
-                        break;
-
-                    default:
-                        // Emit all other workflow events for observability (DevUI, logging, etc.)
-                        yield return new AgentResponseUpdate(ChatRole.Assistant, [])
-                        {
-                            CreatedAt = DateTimeOffset.UtcNow,
-                            MessageId = Guid.NewGuid().ToString("N"),
-                            Role = ChatRole.Assistant,
-                            ResponseId = this.LastResponseId,
-                            RawRepresentation = evt
-                        };
-                        break;
-                }
-            }
-        }
-        finally
        {
-            // Do we want to try to undo the step, and not update the bookmark?
-            this.ChatHistoryProvider.UpdateBookmark(this);
+            switch (evt)
+            {
+                case AgentResponseUpdateEvent agentUpdate:
+                    yield return agentUpdate.Update;
+                    break;
+
+                case RequestInfoEvent requestInfo:
+                    AIContent requestContent = CreateRequestContentForDelivery(requestInfo.Request);
+
+                    // Track the pending request so we can convert incoming responses back to ExternalResponse.
+                    // External callers respond using the workflow-facing request ID, which is always RequestId.
+                    this.AddPendingRequest(requestInfo.Request.RequestId, requestInfo.Request);
+
+                    AgentResponseUpdate update = this.CreateUpdate(this.LastResponseId, evt, requestContent);
+                    yield return update;
+                    break;
+
+                case WorkflowErrorEvent workflowError:
+                    Exception? exception = workflowError.Exception;
+                    if (exception is TargetInvocationException tie && tie.InnerException != null)
+                    {
+                        exception = tie.InnerException;
+                    }
+
+                    if (exception != null)
+                    {
+                        string message = this._includeExceptionDetails
+                                       ? exception.Message
+                                       : "An error occurred while executing the workflow.";
+
+                        ErrorContent errorContent = new(message);
+                        yield return this.CreateUpdate(this.LastResponseId, evt, errorContent);
+                    }
+
+                    break;
+
+                case SuperStepCompletedEvent stepCompleted:
+                    this.LastCheckpoint = stepCompleted.CompletionInfo?.Checkpoint;
+                    goto default;
+
+                case WorkflowOutputEvent output:
+                    IEnumerable<ChatMessage>? updateMessages = output.Data switch
+                    {
+                        IEnumerable<ChatMessage> chatMessages => chatMessages,
+                        ChatMessage chatMessage => [chatMessage],
+                        _ => null
+                    };
+
+                    if (!this._includeWorkflowOutputsInResponse || updateMessages == null)
+                    {
+                        goto default;
+                    }
+
+                    foreach (ChatMessage message in updateMessages)
+                    {
+                        yield return this.CreateUpdate(this.LastResponseId, evt, message);
+                    }
+                    break;
+
+                default:
+                    // Emit all other workflow events for observability (DevUI, logging, etc.)
+                    yield return new AgentResponseUpdate(ChatRole.Assistant, [])
+                    {
+                        CreatedAt = DateTimeOffset.UtcNow,
+                        MessageId = Guid.NewGuid().ToString("N"),
+                        Role = ChatRole.Assistant,
+                        ResponseId = this.LastResponseId,
+                        RawRepresentation = evt
+                    };
+                    break;
+            }
        }
    }

@@ -267,15 +428,116 @@ internal sealed class WorkflowSession : AgentSession
    /// <inheritdoc/>
    public WorkflowChatHistoryProvider ChatHistoryProvider { get; }

+    /// <summary>
+    /// Captures the outcome of creating or resuming a workflow run,
+    /// indicating what types of messages were sent during resume.
+    /// </summary>
+    private readonly struct ResumeRunResult
+    {
+        /// <summary>The streaming run that was created or resumed.</summary>
+        public StreamingRun Run { get; }
+
+        /// <summary>How resume-time content was dispatched into the workflow runtime.</summary>
+        public ResumeDispatchInfo DispatchInfo { get; }
+
+        public ResumeRunResult(StreamingRun run, ResumeDispatchInfo dispatchInfo = default)
+        {
+            this.Run = Throw.IfNull(run);
+            this.DispatchInfo = dispatchInfo;
+        }
+    }
+
+    /// <summary>
+    /// Captures how resumed input was split across regular-message and external-response delivery paths.
+    /// </summary>
+    private readonly struct ResumeDispatchInfo
+    {
+        public ResumeDispatchInfo(bool hasRegularMessages, bool hasMatchedExternalResponses, bool hasMatchedResponseForStartExecutor)
+        {
+            this.HasRegularMessages = hasRegularMessages;
+            this.HasMatchedExternalResponses = hasMatchedExternalResponses;
+            this.HasMatchedResponseForStartExecutor = hasMatchedResponseForStartExecutor;
+        }
+
+        public bool HasRegularMessages { get; }
+
+        public bool HasMatchedExternalResponses { get; }
+
+        public bool HasMatchedResponseForStartExecutor { get; }
+    }
+
+    /// <summary>
+    /// Clones a <see cref="FunctionCallContent"/> with a workflow-facing call ID.
+    /// </summary>
+    private static FunctionCallContent CloneFunctionCallContent(FunctionCallContent content, string callId)
+    {
+        FunctionCallContent clone = new(callId, content.Name, content.Arguments)
+        {
+            Exception = content.Exception,
+            InformationalOnly = content.InformationalOnly,
+        };
+
+        return CopyContentMetadata(content, clone);
+    }
+
+    /// <summary>
+    /// Clones a <see cref="FunctionResultContent"/> with an agent-owned call ID.
+    /// </summary>
+    private static FunctionResultContent CloneFunctionResultContent(FunctionResultContent content, string callId)
+    {
+        FunctionResultContent clone = new(callId, content.Result)
+        {
+            Exception = content.Exception,
+        };
+
+        return CopyContentMetadata(content, clone);
+    }
+
+    /// <summary>
+    /// Clones a <see cref="ToolApprovalRequestContent"/> with a workflow-facing request ID.
+    /// </summary>
+    private static ToolApprovalRequestContent CloneToolApprovalRequestContent(ToolApprovalRequestContent content, string id)
+    {
+        ToolApprovalRequestContent clone = new(id, content.ToolCall);
+        return CopyContentMetadata(content, clone);
+    }
+
+    /// <summary>
+    /// Clones a <see cref="ToolApprovalResponseContent"/> with an agent-owned request ID.
+    /// </summary>
+    private static ToolApprovalResponseContent CloneToolApprovalResponseContent(ToolApprovalResponseContent content, string id)
+    {
+        ToolApprovalResponseContent clone = new(id, content.Approved, content.ToolCall)
+        {
+            Reason = content.Reason,
+        };
+
+        return CopyContentMetadata(content, clone);
+    }
+
+    /// <summary>
+    /// Copies shared <see cref="AIContent"/> metadata to a cloned content instance.
+    /// </summary>
+    private static TContent CopyContentMetadata<TContent>(AIContent source, TContent target)
+        where TContent : AIContent
+    {
+        target.AdditionalProperties = source.AdditionalProperties;
+        target.Annotations = source.Annotations;
+        target.RawRepresentation = source.RawRepresentation;
+        return target;
+    }
+
    internal sealed class SessionState(
        string sessionId,
        CheckpointInfo? lastCheckpoint,
        InMemoryCheckpointManager? checkpointManager = null,
-        AgentSessionStateBag? stateBag = null)
+        AgentSessionStateBag? stateBag = null,
+        Dictionary<string, ExternalRequest>? pendingRequests = null)
    {
        public string SessionId { get; } = sessionId;
        public CheckpointInfo? LastCheckpoint { get; } = lastCheckpoint;
        public InMemoryCheckpointManager? CheckpointManager { get; } = checkpointManager;
        public AgentSessionStateBag StateBag { get; } = stateBag ?? new();
+        public Dictionary<string, ExternalRequest>? PendingRequests { get; } = pendingRequests;
    }
 }
@@ -71,6 +71,7 @@ internal static partial class WorkflowsJsonUtilities
    [JsonSerializable(typeof(PortableValue))]
    [JsonSerializable(typeof(PortableMessageEnvelope))]
    [JsonSerializable(typeof(InMemoryCheckpointManager))]
+    [JsonSerializable(typeof(CheckpointFileIndexEntry))]

    // Runtime State Types
    [JsonSerializable(typeof(ScopeKey))]
@@ -161,6 +161,8 @@ internal sealed class AIContextProviderChatClient : DelegatingChatClient
        }

        // Materialize the accumulated context back into messages and options.
+        // Clone options to avoid mutating the caller's instance across calls.
+        options = options?.Clone();
        var enrichedMessages = aiContext.Messages ?? [];

        var tools = aiContext.Tools as IList<AITool> ?? aiContext.Tools?.ToList();
@@ -788,6 +788,13 @@ public sealed partial class ChatClientAgent : AIAgent
            chatOptions.ConversationId = typedSession.ConversationId;
        }

+        // When per-service-call persistence is active, set a sentinel conversation ID so that
+        // FunctionInvokingChatClient treats locally-persisted history the same as service-managed
+        // history. This prevents it from adding duplicate FunctionCallContent messages into the
+        // request when processing approval responses — the loaded history already contains them.
+        // ChatHistoryPersistingChatClient strips the sentinel before forwarding to the inner client.
+        chatOptions = this.SetLocalHistoryConversationIdIfNeeded(chatOptions);
+
        // Materialize the accumulated messages once at the end of the provider pipeline, reusing the existing list if possible.
        List<ChatMessage> messagesList = inputMessagesForChatClient as List<ChatMessage> ?? inputMessagesForChatClient.ToList();

@@ -929,6 +936,26 @@ public sealed partial class ChatClientAgent : AIAgent
        }
    }

+    /// <summary>
+    /// Sets the <see cref="ChatHistoryPersistingChatClient.LocalHistoryConversationId"/> sentinel on
+    /// <paramref name="chatOptions"/> when per-service-call persistence is active and no real
+    /// conversation ID is present.
+    /// </summary>
+    /// <returns>
+    /// The (possibly new) <see cref="ChatOptions"/> with the sentinel set, or the original
+    /// <paramref name="chatOptions"/> if no sentinel is needed.
+    /// </returns>
+    private ChatOptions? SetLocalHistoryConversationIdIfNeeded(ChatOptions? chatOptions)
+    {
+        if (this.PersistsChatHistoryPerServiceCall && string.IsNullOrWhiteSpace(chatOptions?.ConversationId))
+        {
+            chatOptions ??= new ChatOptions();
+            chatOptions.ConversationId = ChatHistoryPersistingChatClient.LocalHistoryConversationId;
+        }
+
+        return chatOptions;
+    }
+
    /// <summary>
    /// Gets a value indicating whether the agent has a <see cref="ChatHistoryPersistingChatClient"/>
    /// decorator in mark-only mode, which marks messages for later persistence at the end of the run.
@@ -50,6 +50,26 @@ internal sealed class ChatHistoryPersistingChatClient : DelegatingChatClient
    /// </summary>
    internal const string PersistedMarkerKey = "_chatHistoryPersisted";

+    /// <summary>
+    /// A sentinel value set on <see cref="ChatOptions.ConversationId"/> by <see cref="ChatClientAgent"/>
+    /// when per-service-call persistence is active and no real conversation ID exists.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// This signals to <see cref="FunctionInvokingChatClient"/> that the chat history is being managed
+    /// externally (by this decorator), which prevents it from adding duplicate <see cref="FunctionCallContent"/>
+    /// messages into the request during approval-response processing. Without this sentinel,
+    /// <see cref="FunctionInvokingChatClient"/> would reconstruct function-call messages from approval
+    /// responses and append them to the original messages — but the loaded history already contains
+    /// those same function calls, causing duplicate tool-call entries that the model rejects.
+    /// </para>
+    /// <para>
+    /// This decorator strips the sentinel before forwarding requests to the inner client, so the
+    /// underlying model never sees it.
+    /// </para>
+    /// </remarks>
+    internal const string LocalHistoryConversationId = "_agent_local_history";
+
    /// <summary>
    /// Initializes a new instance of the <see cref="ChatHistoryPersistingChatClient"/> class.
    /// </summary>
@@ -87,6 +107,7 @@ internal sealed class ChatHistoryPersistingChatClient : DelegatingChatClient
        CancellationToken cancellationToken = default)
    {
        var (agent, session) = GetRequiredAgentAndSession();
+        options = StripLocalHistoryConversationId(options);

        ChatResponse response;
        try
@@ -130,6 +151,7 @@ internal sealed class ChatHistoryPersistingChatClient : DelegatingChatClient
        [EnumeratorCancellation] CancellationToken cancellationToken = default)
    {
        var (agent, session) = GetRequiredAgentAndSession();
+        options = StripLocalHistoryConversationId(options);

        List<ChatResponseUpdate> responseUpdates = [];

@@ -310,4 +332,20 @@ internal sealed class ChatHistoryPersistingChatClient : DelegatingChatClient
            }
        }
    }
+
+    /// <summary>
+    /// If the <paramref name="options"/> carry the <see cref="LocalHistoryConversationId"/> sentinel,
+    /// returns a clone with the conversation ID cleared so the inner client never sees it.
+    /// Otherwise returns the original <paramref name="options"/> unchanged.
+    /// </summary>
+    private static ChatOptions? StripLocalHistoryConversationId(ChatOptions? options)
+    {
+        if (options?.ConversationId == LocalHistoryConversationId)
+        {
+            options = options.Clone();
+            options.ConversationId = null;
+        }
+
+        return options;
+    }
 }
@@ -0,0 +1,58 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.Shared.DiagnosticIds;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// Abstract base class for all agent skills.
+/// </summary>
+/// <remarks>
+/// <para>
+/// A skill represents a domain-specific capability with instructions, resources, and scripts.
+/// Concrete implementations include <see cref="AgentFileSkill"/> (filesystem-backed).
+/// </para>
+/// <para>
+/// Skill metadata follows the <see href="https://agentskills.io/specification">Agent Skills specification</see>.
+/// </para>
+/// </remarks>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public abstract class AgentSkill
+{
+    /// <summary>
+    /// Gets the frontmatter metadata for this skill.
+    /// </summary>
+    /// <remarks>
+    /// Contains the L1 discovery metadata (name, description, license, compatibility, etc.)
+    /// as defined by the <see href="https://agentskills.io/specification">Agent Skills specification</see>.
+    /// </remarks>
+    public abstract AgentSkillFrontmatter Frontmatter { get; }
+
+    /// <summary>
+    /// Gets the full skill content.
+    /// </summary>
+    /// <remarks>
+    /// For file-based skills this is the raw SKILL.md file content.
+    /// </remarks>
+    public abstract string Content { get; }
+
+    /// <summary>
+    /// Gets the resources associated with this skill, or <see langword="null"/> if none.
+    /// </summary>
+    /// <remarks>
+    /// The default implementation returns <see langword="null"/>.
+    /// Override this property in derived classes to provide skill-specific resources.
+    /// </remarks>
+    public virtual IReadOnlyList<AgentSkillResource>? Resources => null;
+
+    /// <summary>
+    /// Gets the scripts associated with this skill, or <see langword="null"/> if none.
+    /// </summary>
+    /// <remarks>
+    /// The default implementation returns <see langword="null"/>.
+    /// Override this property in derived classes to provide skill-specific scripts.
+    /// </remarks>
+    public virtual IReadOnlyList<AgentSkillScript>? Scripts => null;
+}
@@ -0,0 +1,196 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Text.RegularExpressions;
+using Microsoft.Extensions.AI;
+using Microsoft.Shared.DiagnosticIds;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// Represents the YAML frontmatter metadata parsed from a SKILL.md file.
+/// </summary>
+/// <remarks>
+/// <para>
+/// Frontmatter is the L1 (discovery) layer of the
+/// <see href="https://agentskills.io/specification">Agent Skills specification</see>.
+/// It contains the minimal metadata needed to advertise a skill in the system prompt
+/// without loading the full skill content.
+/// </para>
+/// <para>
+/// The constructor validates the name and description against specification rules
+/// and throws <see cref="ArgumentException"/> if either value is invalid.
+/// </para>
+/// </remarks>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public sealed class AgentSkillFrontmatter
+{
+    /// <summary>
+    /// Maximum allowed length for the skill name.
+    /// </summary>
+    internal const int MaxNameLength = 64;
+
+    /// <summary>
+    /// Maximum allowed length for the skill description.
+    /// </summary>
+    internal const int MaxDescriptionLength = 1024;
+
+    /// <summary>
+    /// Maximum allowed length for the compatibility field.
+    /// </summary>
+    internal const int MaxCompatibilityLength = 500;
+
+    // Validates skill names per the Agent Skills specification (https://agentskills.io/specification#frontmatter):
+    // lowercase letters, numbers, and hyphens only; must not start or end with a hyphen; must not contain consecutive hyphens.
+    private static readonly Regex s_validNameRegex = new("^[a-z0-9]([a-z0-9]*-[a-z0-9])*[a-z0-9]*$", RegexOptions.Compiled);
+
+    private string? _compatibility;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AgentSkillFrontmatter"/> class.
+    /// </summary>
+    /// <param name="name">Skill name in kebab-case.</param>
+    /// <param name="description">Skill description for discovery.</param>
+    /// <param name="compatibility">Optional compatibility information (max 500 chars).</param>
+    /// <exception cref="ArgumentException">
+    /// Thrown when <paramref name="name"/>, <paramref name="description"/>, or <paramref name="compatibility"/> violates the
+    /// <see href="https://agentskills.io/specification">Agent Skills specification</see> rules.
+    /// </exception>
+    public AgentSkillFrontmatter(string name, string description, string? compatibility = null)
+    {
+        if (!ValidateName(name, out string? reason) ||
+            !ValidateDescription(description, out reason) ||
+            !ValidateCompatibility(compatibility, out reason))
+        {
+            throw new ArgumentException(reason);
+        }
+
+        this.Name = name;
+        this.Description = description;
+        this._compatibility = compatibility;
+    }
+
+    /// <summary>
+    /// Gets the skill name. Lowercase letters, numbers, and hyphens only; no leading, trailing, or consecutive hyphens.
+    /// </summary>
+    public string Name { get; }
+
+    /// <summary>
+    /// Gets the skill description. Used for discovery in the system prompt.
+    /// </summary>
+    public string Description { get; }
+
+    /// <summary>
+    /// Gets or sets an optional license name or reference.
+    /// </summary>
+    public string? License { get; set; }
+
+    /// <summary>
+    /// Gets or sets optional compatibility information (max 500 chars).
+    /// </summary>
+    /// <exception cref="ArgumentException">
+    /// Thrown when the value exceeds <see cref="MaxCompatibilityLength"/> characters.
+    /// </exception>
+    public string? Compatibility
+    {
+        get => this._compatibility;
+        set
+        {
+            if (!ValidateCompatibility(value, out string? reason))
+            {
+                throw new ArgumentException(reason);
+            }
+
+            this._compatibility = value;
+        }
+    }
+
+    /// <summary>
+    /// Gets or sets optional space-delimited list of pre-approved tools.
+    /// </summary>
+    public string? AllowedTools { get; set; }
+
+    /// <summary>
+    /// Gets or sets the arbitrary key-value metadata for this skill.
+    /// </summary>
+    public AdditionalPropertiesDictionary? Metadata { get; set; }
+
+    /// <summary>
+    /// Validates a skill name against specification rules.
+    /// </summary>
+    /// <param name="name">The skill name to validate (may be <see langword="null"/>).</param>
+    /// <param name="reason">When validation fails, contains a human-readable description of the failure.</param>
+    /// <returns><see langword="true"/> if the name is valid; otherwise, <see langword="false"/>.</returns>
+    public static bool ValidateName(
+        string? name,
+        [NotNullWhen(false)] out string? reason)
+    {
+        if (string.IsNullOrWhiteSpace(name))
+        {
+            reason = "Skill name is required.";
+            return false;
+        }
+
+        if (name.Length > MaxNameLength)
+        {
+            reason = $"Skill name must be {MaxNameLength} characters or fewer.";
+            return false;
+        }
+
+        if (!s_validNameRegex.IsMatch(name))
+        {
+            reason = "Skill name must use only lowercase letters, numbers, and hyphens, and must not start or end with a hyphen or contain consecutive hyphens.";
+            return false;
+        }
+
+        reason = null;
+        return true;
+    }
+
+    /// <summary>
+    /// Validates a skill description against specification rules.
+    /// </summary>
+    /// <param name="description">The skill description to validate (may be <see langword="null"/>).</param>
+    /// <param name="reason">When validation fails, contains a human-readable description of the failure.</param>
+    /// <returns><see langword="true"/> if the description is valid; otherwise, <see langword="false"/>.</returns>
+    public static bool ValidateDescription(
+        string? description,
+        [NotNullWhen(false)] out string? reason)
+    {
+        if (string.IsNullOrWhiteSpace(description))
+        {
+            reason = "Skill description is required.";
+            return false;
+        }
+
+        if (description.Length > MaxDescriptionLength)
+        {
+            reason = $"Skill description must be {MaxDescriptionLength} characters or fewer.";
+            return false;
+        }
+
+        reason = null;
+        return true;
+    }
+
+    /// <summary>
+    /// Validates an optional skill compatibility value against specification rules.
+    /// </summary>
+    /// <param name="compatibility">The optional compatibility value to validate (may be <see langword="null"/>).</param>
+    /// <param name="reason">When validation fails, contains a human-readable description of the failure.</param>
+    /// <returns><see langword="true"/> if the value is valid; otherwise, <see langword="false"/>.</returns>
+    public static bool ValidateCompatibility(
+        string? compatibility,
+        [NotNullWhen(false)] out string? reason)
+    {
+        if (compatibility?.Length > MaxCompatibilityLength)
+        {
+            reason = $"Skill compatibility must be {MaxCompatibilityLength} characters or fewer.";
+            return false;
+        }
+
+        reason = null;
+        return true;
+    }
+}
@@ -0,0 +1,46 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// Abstract base class for skill resources. A resource provides supplementary content (references, assets) to a skill.
+/// </summary>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public abstract class AgentSkillResource
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AgentSkillResource"/> class.
+    /// </summary>
+    /// <param name="name">The resource name (e.g., relative path or identifier).</param>
+    /// <param name="description">An optional description of the resource.</param>
+    protected AgentSkillResource(string name, string? description = null)
+    {
+        this.Name = Throw.IfNullOrWhitespace(name);
+        this.Description = description;
+    }
+
+    /// <summary>
+    /// Gets the resource name.
+    /// </summary>
+    public string Name { get; }
+
+    /// <summary>
+    /// Gets the optional resource description.
+    /// </summary>
+    public string? Description { get; }
+
+    /// <summary>
+    /// Reads the resource content asynchronously.
+    /// </summary>
+    /// <param name="serviceProvider">Optional service provider for dependency injection.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>The resource content.</returns>
+    public abstract Task<object?> ReadAsync(IServiceProvider? serviceProvider = null, CancellationToken cancellationToken = default);
+}
@@ -0,0 +1,47 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.AI;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// Abstract base class for skill scripts. A script represents an executable action associated with a skill.
+/// </summary>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public abstract class AgentSkillScript
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AgentSkillScript"/> class.
+    /// </summary>
+    /// <param name="name">The script name.</param>
+    /// <param name="description">An optional description of the script.</param>
+    protected AgentSkillScript(string name, string? description = null)
+    {
+        this.Name = Throw.IfNullOrWhitespace(name);
+        this.Description = description;
+    }
+
+    /// <summary>
+    /// Gets the script name.
+    /// </summary>
+    public string Name { get; }
+
+    /// <summary>
+    /// Gets the optional script description.
+    /// </summary>
+    public string? Description { get; }
+
+    /// <summary>
+    /// Runs the script with the given arguments.
+    /// </summary>
+    /// <param name="skill">The skill that owns this script.</param>
+    /// <param name="arguments">Arguments for script execution.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>The script execution result.</returns>
+    public abstract Task<object?> RunAsync(AgentSkill skill, AIFunctionArguments arguments, CancellationToken cancellationToken = default);
+}
@@ -0,0 +1,383 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Security;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.AI;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// An <see cref="AIContextProvider"/> that exposes agent skills from one or more <see cref="AgentSkillsSource"/> instances.
+/// </summary>
+/// <remarks>
+/// <para>
+/// This provider implements the progressive disclosure pattern from the
+/// <see href="https://agentskills.io/">Agent Skills specification</see>:
+/// </para>
+/// <list type="number">
+/// <item><description><strong>Advertise</strong> — skill names and descriptions are injected into the system prompt.</description></item>
+/// <item><description><strong>Load</strong> — the full skill body is returned via the <c>load_skill</c> tool.</description></item>
+/// <item><description><strong>Read resources</strong> — supplementary content is read on demand via the <c>read_skill_resource</c> tool.</description></item>
+/// <item><description><strong>Run scripts</strong> — scripts are executed via the <c>run_skill_script</c> tool (when scripts exist).</description></item>
+/// </list>
+/// </remarks>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public sealed partial class AgentSkillsProvider : AIContextProvider
+{
+    /// <summary>
+    /// Placeholder token for the generated skills list in the prompt template.
+    /// </summary>
+    private const string SkillsPlaceholder = "{skills}";
+
+    /// <summary>
+    /// Placeholder token for the script instructions in the prompt template.
+    /// </summary>
+    private const string ScriptInstructionsPlaceholder = "{script_instructions}";
+
+    /// <summary>
+    /// Placeholder token for the resource instructions in the prompt template.
+    /// </summary>
+    private const string ResourceInstructionsPlaceholder = "{resource_instructions}";
+
+    private const string DefaultSkillsInstructionPrompt =
+        """
+        You have access to skills containing domain-specific knowledge and capabilities.
+        Each skill provides specialized instructions, reference documents, and assets for specific tasks.
+
+        <available_skills>
+        {skills}
+        </available_skills>
+
+        When a task aligns with a skill's domain, follow these steps in exact order:
+        - Use `load_skill` to retrieve the skill's instructions.
+        - Follow the provided guidance.
+        {resource_instructions}
+        {script_instructions}
+        Only load what is needed, when it is needed.
+        """;
+
+    private readonly AgentSkillsSource _source;
+    private readonly AgentSkillsProviderOptions? _options;
+    private readonly ILogger<AgentSkillsProvider> _logger;
+    private Task<AIContext>? _contextTask;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AgentSkillsProvider"/> class
+    /// that discovers file-based skills from a single directory.
+    /// Duplicate skill names are automatically deduplicated (first occurrence wins).
+    /// </summary>
+    /// <param name="skillPath">Path to search for skills.</param>
+    /// <param name="scriptRunner">Optional delegate that runs file-based scripts. Required only when skills contain scripts.</param>
+    /// <param name="fileOptions">Optional options that control skill discovery behavior.</param>
+    /// <param name="options">Optional provider configuration.</param>
+    /// <param name="loggerFactory">Optional logger factory.</param>
+    public AgentSkillsProvider(
+        string skillPath,
+        AgentFileSkillScriptRunner? scriptRunner = null,
+        AgentFileSkillsSourceOptions? fileOptions = null,
+        AgentSkillsProviderOptions? options = null,
+        ILoggerFactory? loggerFactory = null)
+        : this([Throw.IfNull(skillPath)], scriptRunner, fileOptions, options, loggerFactory)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AgentSkillsProvider"/> class
+    /// that discovers file-based skills from multiple directories.
+    /// Duplicate skill names are automatically deduplicated (first occurrence wins).
+    /// </summary>
+    /// <param name="skillPaths">Paths to search for skills.</param>
+    /// <param name="scriptRunner">Optional delegate that runs file-based scripts. Required only when skills contain scripts.</param>
+    /// <param name="fileOptions">Optional options that control skill discovery behavior.</param>
+    /// <param name="options">Optional provider configuration.</param>
+    /// <param name="loggerFactory">Optional logger factory.</param>
+    public AgentSkillsProvider(
+        IEnumerable<string> skillPaths,
+        AgentFileSkillScriptRunner? scriptRunner = null,
+        AgentFileSkillsSourceOptions? fileOptions = null,
+        AgentSkillsProviderOptions? options = null,
+        ILoggerFactory? loggerFactory = null)
+        : this(
+            new DeduplicatingAgentSkillsSource(
+                new AgentFileSkillsSource(skillPaths, scriptRunner, fileOptions, loggerFactory),
+                loggerFactory),
+            options,
+            loggerFactory)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AgentSkillsProvider"/> class
+    /// from a custom <see cref="AgentSkillsSource"/>. Unlike other constructors, this one does not
+    /// apply automatic deduplication, allowing callers to customize deduplication behavior via the source pipeline.
+    /// </summary>
+    /// <param name="source">The skill source providing skills.</param>
+    /// <param name="options">Optional configuration.</param>
+    /// <param name="loggerFactory">Optional logger factory.</param>
+    public AgentSkillsProvider(AgentSkillsSource source, AgentSkillsProviderOptions? options = null, ILoggerFactory? loggerFactory = null)
+    {
+        this._source = Throw.IfNull(source);
+        this._options = options;
+        this._logger = (loggerFactory ?? NullLoggerFactory.Instance).CreateLogger<AgentSkillsProvider>();
+
+        if (options?.SkillsInstructionPrompt is string prompt)
+        {
+            ValidatePromptTemplate(prompt, nameof(options));
+        }
+    }
+
+    /// <inheritdoc />
+    protected override async ValueTask<AIContext> ProvideAIContextAsync(InvokingContext context, CancellationToken cancellationToken = default)
+    {
+        if (this._options?.DisableCaching == true)
+        {
+            return await this.CreateContextAsync(context, cancellationToken).ConfigureAwait(false);
+        }
+
+        return await this.GetOrCreateContextAsync(context, cancellationToken).ConfigureAwait(false);
+    }
+
+    private async Task<AIContext> CreateContextAsync(InvokingContext context, CancellationToken cancellationToken)
+    {
+        var skills = await this._source.GetSkillsAsync(cancellationToken).ConfigureAwait(false);
+        if (skills is not { Count: > 0 })
+        {
+            return await base.ProvideAIContextAsync(context, cancellationToken).ConfigureAwait(false);
+        }
+
+        bool hasScripts = skills.Any(s => s.Scripts is { Count: > 0 });
+        bool hasResources = skills.Any(s => s.Resources is { Count: > 0 });
+
+        return new AIContext
+        {
+            Instructions = this.BuildSkillsInstructions(skills, includeScriptInstructions: hasScripts, hasResources),
+            Tools = this.BuildTools(skills, hasScripts, hasResources),
+        };
+    }
+
+    private async Task<AIContext> GetOrCreateContextAsync(InvokingContext context, CancellationToken cancellationToken)
+    {
+        var tcs = new TaskCompletionSource<AIContext>(TaskCreationOptions.RunContinuationsAsynchronously);
+
+        if (Interlocked.CompareExchange(ref this._contextTask, tcs.Task, null) is { } existing)
+        {
+            return await existing.ConfigureAwait(false);
+        }
+
+        try
+        {
+            var result = await this.CreateContextAsync(context, cancellationToken).ConfigureAwait(false);
+            tcs.SetResult(result);
+            return result;
+        }
+        catch (Exception ex)
+        {
+            this._contextTask = null;
+            tcs.TrySetException(ex);
+            throw;
+        }
+    }
+
+    private IList<AIFunction> BuildTools(IList<AgentSkill> skills, bool hasScripts, bool hasResources)
+    {
+        IList<AIFunction> tools =
+        [
+            AIFunctionFactory.Create(
+                (string skillName) => this.LoadSkill(skills, skillName),
+                name: "load_skill",
+                description: "Loads the full content of a specific skill"),
+        ];
+
+        if (hasResources)
+        {
+            tools.Add(AIFunctionFactory.Create(
+                (string skillName, string resourceName, IServiceProvider? serviceProvider, CancellationToken cancellationToken = default) =>
+                    this.ReadSkillResourceAsync(skills, skillName, resourceName, serviceProvider, cancellationToken),
+                name: "read_skill_resource",
+                description: "Reads a resource associated with a skill, such as references, assets, or dynamic data."));
+        }
+
+        if (!hasScripts)
+        {
+            return tools;
+        }
+
+        AIFunction scriptFunction = AIFunctionFactory.Create(
+            (string skillName, string scriptName, IDictionary<string, object?>? arguments = null, IServiceProvider? serviceProvider = null, CancellationToken cancellationToken = default) =>
+                this.RunSkillScriptAsync(skills, skillName, scriptName, arguments, serviceProvider, cancellationToken),
+            name: "run_skill_script",
+            description: "Runs a script associated with a skill.");
+
+        if (this._options?.ScriptApproval == true)
+        {
+            return [.. tools, new ApprovalRequiredAIFunction(scriptFunction)];
+        }
+
+        return [.. tools, scriptFunction];
+    }
+
+    private string? BuildSkillsInstructions(IList<AgentSkill> skills, bool includeScriptInstructions, bool includeResourceInstructions)
+    {
+        string promptTemplate = this._options?.SkillsInstructionPrompt ?? DefaultSkillsInstructionPrompt;
+
+        var sb = new StringBuilder();
+        foreach (var skill in skills.OrderBy(s => s.Frontmatter.Name, StringComparer.Ordinal))
+        {
+            sb.AppendLine("  <skill>");
+            sb.AppendLine($"    <name>{SecurityElement.Escape(skill.Frontmatter.Name)}</name>");
+            sb.AppendLine($"    <description>{SecurityElement.Escape(skill.Frontmatter.Description)}</description>");
+            sb.AppendLine("  </skill>");
+        }
+
+        string resourceInstruction = includeResourceInstructions
+            ? """
+            - Use `read_skill_resource` to read any referenced resources, using the name exactly as listed
+               (e.g. `"style-guide"` not `"style-guide.md"`, `"references/FAQ.md"` not `"FAQ.md"`).
+            """
+            : string.Empty;
+
+        string scriptInstruction = includeScriptInstructions
+            ? "- Use `run_skill_script` to run referenced scripts, using the name exactly as listed."
+            : string.Empty;
+
+        return new StringBuilder(promptTemplate)
+            .Replace(SkillsPlaceholder, sb.ToString().TrimEnd())
+            .Replace(ResourceInstructionsPlaceholder, resourceInstruction)
+            .Replace(ScriptInstructionsPlaceholder, scriptInstruction)
+            .ToString();
+    }
+
+    private string LoadSkill(IList<AgentSkill> skills, string skillName)
+    {
+        if (string.IsNullOrWhiteSpace(skillName))
+        {
+            return "Error: Skill name cannot be empty.";
+        }
+
+        var skill = skills?.FirstOrDefault(skill => skill.Frontmatter.Name == skillName);
+        if (skill == null)
+        {
+            return $"Error: Skill '{skillName}' not found.";
+        }
+
+        LogSkillLoading(this._logger, skillName);
+
+        return skill.Content;
+    }
+
+    private async Task<object?> ReadSkillResourceAsync(IList<AgentSkill> skills, string skillName, string resourceName, IServiceProvider? serviceProvider, CancellationToken cancellationToken = default)
+    {
+        if (string.IsNullOrWhiteSpace(skillName))
+        {
+            return "Error: Skill name cannot be empty.";
+        }
+
+        if (string.IsNullOrWhiteSpace(resourceName))
+        {
+            return "Error: Resource name cannot be empty.";
+        }
+
+        var skill = skills?.FirstOrDefault(skill => skill.Frontmatter.Name == skillName);
+        if (skill == null)
+        {
+            return $"Error: Skill '{skillName}' not found.";
+        }
+
+        var resource = skill.Resources?.FirstOrDefault(resource => resource.Name == resourceName);
+        if (resource is null)
+        {
+            return $"Error: Resource '{resourceName}' not found in skill '{skillName}'.";
+        }
+
+        try
+        {
+            return await resource.ReadAsync(serviceProvider, cancellationToken).ConfigureAwait(false);
+        }
+        catch (Exception ex)
+        {
+            LogResourceReadError(this._logger, skillName, resourceName, ex);
+            return $"Error: Failed to read resource '{resourceName}' from skill '{skillName}'.";
+        }
+    }
+
+    private async Task<object?> RunSkillScriptAsync(IList<AgentSkill> skills, string skillName, string scriptName, IDictionary<string, object?>? arguments = null, IServiceProvider? serviceProvider = null, CancellationToken cancellationToken = default)
+    {
+        if (string.IsNullOrWhiteSpace(skillName))
+        {
+            return "Error: Skill name cannot be empty.";
+        }
+
+        if (string.IsNullOrWhiteSpace(scriptName))
+        {
+            return "Error: Script name cannot be empty.";
+        }
+
+        var skill = skills?.FirstOrDefault(skill => skill.Frontmatter.Name == skillName);
+        if (skill == null)
+        {
+            return $"Error: Skill '{skillName}' not found.";
+        }
+
+        var script = skill.Scripts?.FirstOrDefault(resource => resource.Name == scriptName);
+        if (script is null)
+        {
+            return $"Error: Script '{scriptName}' not found in skill '{skillName}'.";
+        }
+
+        try
+        {
+            return await script.RunAsync(skill, new AIFunctionArguments(arguments) { Services = serviceProvider }, cancellationToken).ConfigureAwait(false);
+        }
+        catch (Exception ex)
+        {
+            LogScriptExecutionError(this._logger, skillName, scriptName, ex);
+            return $"Error: Failed to execute script '{scriptName}' from skill '{skillName}'.";
+        }
+    }
+
+    /// <summary>
+    /// Validates that a custom prompt template contains the required placeholder tokens.
+    /// </summary>
+    private static void ValidatePromptTemplate(string template, string paramName)
+    {
+        if (template.IndexOf(SkillsPlaceholder, StringComparison.Ordinal) < 0)
+        {
+            throw new ArgumentException(
+                $"The custom prompt template must contain the '{SkillsPlaceholder}' placeholder for the generated skills list.",
+                paramName);
+        }
+
+        if (template.IndexOf(ResourceInstructionsPlaceholder, StringComparison.Ordinal) < 0)
+        {
+            throw new ArgumentException(
+                $"The custom prompt template must contain the '{ResourceInstructionsPlaceholder}' placeholder for resource instructions.",
+                paramName);
+        }
+
+        if (template.IndexOf(ScriptInstructionsPlaceholder, StringComparison.Ordinal) < 0)
+        {
+            throw new ArgumentException(
+                $"The custom prompt template must contain the '{ScriptInstructionsPlaceholder}' placeholder for script instructions.",
+                paramName);
+        }
+    }
+
+    [LoggerMessage(LogLevel.Information, "Loading skill: {SkillName}")]
+    private static partial void LogSkillLoading(ILogger logger, string skillName);
+
+    [LoggerMessage(LogLevel.Error, "Failed to read resource '{ResourceName}' from skill '{SkillName}'")]
+    private static partial void LogResourceReadError(ILogger logger, string skillName, string resourceName, Exception exception);
+
+    [LoggerMessage(LogLevel.Error, "Failed to execute script '{ScriptName}' from skill '{SkillName}'")]
+    private static partial void LogScriptExecutionError(ILogger logger, string skillName, string scriptName, Exception exception);
+}
@@ -0,0 +1,192 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.Extensions.Logging;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// Fluent builder for constructing an <see cref="AgentSkillsProvider"/> backed by a composite source.
+/// </summary>
+/// <remarks>
+/// <code>
+/// var provider = new AgentSkillsProviderBuilder()
+///     .UseFileSkills("/path/to/skills")
+///     .Build();
+/// </code>
+/// </remarks>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public sealed class AgentSkillsProviderBuilder
+{
+    private readonly List<Func<AgentFileSkillScriptRunner?, ILoggerFactory?, AgentSkillsSource>> _sourceFactories = [];
+    private AgentSkillsProviderOptions? _options;
+    private ILoggerFactory? _loggerFactory;
+    private AgentFileSkillScriptRunner? _scriptRunner;
+    private Func<AgentSkill, bool>? _filter;
+
+    /// <summary>
+    /// Adds a file-based skill source that discovers skills from a filesystem directory.
+    /// </summary>
+    /// <param name="skillPath">Path to search for skills.</param>
+    /// <param name="options">Optional options that control skill discovery behavior.</param>
+    /// <param name="scriptRunner">
+    /// Optional runner for file-based scripts. When provided, overrides the builder-level runner
+    /// set via <see cref="UseFileScriptRunner"/>.
+    /// </param>
+    /// <returns>This builder instance for chaining.</returns>
+    public AgentSkillsProviderBuilder UseFileSkill(string skillPath, AgentFileSkillsSourceOptions? options = null, AgentFileSkillScriptRunner? scriptRunner = null)
+    {
+        return this.UseFileSkills([skillPath], options, scriptRunner);
+    }
+
+    /// <summary>
+    /// Adds a file-based skill source that discovers skills from multiple filesystem directories.
+    /// </summary>
+    /// <param name="skillPaths">Paths to search for skills.</param>
+    /// <param name="options">Optional options that control skill discovery behavior.</param>
+    /// <param name="scriptRunner">
+    /// Optional runner for file-based scripts. When provided, overrides the builder-level runner
+    /// set via <see cref="UseFileScriptRunner"/>.
+    /// </param>
+    /// <returns>This builder instance for chaining.</returns>
+    public AgentSkillsProviderBuilder UseFileSkills(IEnumerable<string> skillPaths, AgentFileSkillsSourceOptions? options = null, AgentFileSkillScriptRunner? scriptRunner = null)
+    {
+        this._sourceFactories.Add((builderScriptRunner, loggerFactory) =>
+        {
+            var resolvedRunner = scriptRunner
+                ?? builderScriptRunner
+                ?? throw new InvalidOperationException($"File-based skill sources require a script runner. Call {nameof(this.UseFileScriptRunner)} or pass a runner to {nameof(this.UseFileSkill)}/{nameof(this.UseFileSkills)}.");
+            return new AgentFileSkillsSource(skillPaths, resolvedRunner, options, loggerFactory);
+        });
+        return this;
+    }
+
+    /// <summary>
+    /// Adds a custom skill source.
+    /// </summary>
+    /// <param name="source">The custom skill source.</param>
+    /// <returns>This builder instance for chaining.</returns>
+    public AgentSkillsProviderBuilder UseSource(AgentSkillsSource source)
+    {
+        _ = Throw.IfNull(source);
+        this._sourceFactories.Add((_, _) => source);
+        return this;
+    }
+
+    /// <summary>
+    /// Sets a custom system prompt template.
+    /// </summary>
+    /// <param name="promptTemplate">The prompt template with <c>{skills}</c> placeholder for the skills list,
+    /// <c>{resource_instructions}</c> for optional resource instructions,
+    /// and <c>{script_instructions}</c> for optional script instructions.</param>
+    /// <returns>This builder instance for chaining.</returns>
+    public AgentSkillsProviderBuilder UsePromptTemplate(string promptTemplate)
+    {
+        this.GetOrCreateOptions().SkillsInstructionPrompt = promptTemplate;
+        return this;
+    }
+
+    /// <summary>
+    /// Enables or disables the script approval gate.
+    /// </summary>
+    /// <param name="enabled">Whether script execution requires approval.</param>
+    /// <returns>This builder instance for chaining.</returns>
+    public AgentSkillsProviderBuilder UseScriptApproval(bool enabled = true)
+    {
+        this.GetOrCreateOptions().ScriptApproval = enabled;
+        return this;
+    }
+
+    /// <summary>
+    /// Sets the runner for file-based skill scripts.
+    /// </summary>
+    /// <param name="runner">The delegate that runs file-based scripts.</param>
+    /// <returns>This builder instance for chaining.</returns>
+    public AgentSkillsProviderBuilder UseFileScriptRunner(AgentFileSkillScriptRunner runner)
+    {
+        this._scriptRunner = Throw.IfNull(runner);
+        return this;
+    }
+
+    /// <summary>
+    /// Sets the logger factory.
+    /// </summary>
+    /// <param name="loggerFactory">The logger factory.</param>
+    /// <returns>This builder instance for chaining.</returns>
+    public AgentSkillsProviderBuilder UseLoggerFactory(ILoggerFactory loggerFactory)
+    {
+        this._loggerFactory = loggerFactory;
+        return this;
+    }
+
+    /// <summary>
+    /// Sets a filter predicate that controls which skills are included.
+    /// </summary>
+    /// <remarks>
+    /// Skills for which the predicate returns <see langword="true"/> are kept;
+    /// others are excluded. Only one filter is supported; calling this method
+    /// again replaces any previously set filter.
+    /// </remarks>
+    /// <param name="predicate">A predicate that determines which skills to include.</param>
+    /// <returns>This builder instance for chaining.</returns>
+    public AgentSkillsProviderBuilder UseFilter(Func<AgentSkill, bool> predicate)
+    {
+        _ = Throw.IfNull(predicate);
+        this._filter = predicate;
+        return this;
+    }
+
+    /// <summary>
+    /// Configures the <see cref="AgentSkillsProviderOptions"/> using the provided delegate.
+    /// </summary>
+    /// <param name="configure">A delegate to configure the options.</param>
+    /// <returns>This builder instance for chaining.</returns>
+    public AgentSkillsProviderBuilder UseOptions(Action<AgentSkillsProviderOptions> configure)
+    {
+        _ = Throw.IfNull(configure);
+        configure(this.GetOrCreateOptions());
+        return this;
+    }
+
+    /// <summary>
+    /// Builds the <see cref="AgentSkillsProvider"/>.
+    /// </summary>
+    /// <returns>A configured <see cref="AgentSkillsProvider"/>.</returns>
+    public AgentSkillsProvider Build()
+    {
+        var resolvedSources = new List<AgentSkillsSource>(this._sourceFactories.Count);
+        foreach (var factory in this._sourceFactories)
+        {
+            resolvedSources.Add(factory(this._scriptRunner, this._loggerFactory));
+        }
+
+        AgentSkillsSource source;
+        if (resolvedSources.Count == 1)
+        {
+            source = resolvedSources[0];
+        }
+        else
+        {
+            source = new AggregatingAgentSkillsSource(resolvedSources);
+        }
+
+        // Apply user-specified filter, then dedup.
+        if (this._filter != null)
+        {
+            source = new FilteringAgentSkillsSource(source, this._filter, this._loggerFactory);
+        }
+
+        source = new DeduplicatingAgentSkillsSource(source, this._loggerFactory);
+
+        return new AgentSkillsProvider(source, this._options, this._loggerFactory);
+    }
+
+    private AgentSkillsProviderOptions GetOrCreateOptions()
+    {
+        return this._options ??= new AgentSkillsProviderOptions();
+    }
+}
@@ -0,0 +1,37 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.Shared.DiagnosticIds;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// Configuration options for <see cref="AgentSkillsProvider"/>.
+/// </summary>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public sealed class AgentSkillsProviderOptions
+{
+    /// <summary>
+    /// Gets or sets a custom system prompt template for advertising skills.
+    /// The template must contain <c>{skills}</c> as the placeholder for the generated skills list,
+    /// <c>{resource_instructions}</c> for resource instructions,
+    /// and <c>{script_instructions}</c> for script instructions.
+    /// When <see langword="null"/>, a default template is used.
+    /// </summary>
+    public string? SkillsInstructionPrompt { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether script execution requires approval.
+    /// When <see langword="true"/>, script execution is blocked until approved.
+    /// Defaults to <see langword="false"/>.
+    /// </summary>
+    public bool ScriptApproval { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether caching of tools and instructions is disabled.
+    /// When <see langword="false"/> (the default), the provider caches the tools and instructions
+    /// after the first build and returns the cached instance on subsequent calls.
+    /// Set to <see langword="true"/> to rebuild tools and instructions on every invocation.
+    /// </summary>
+    public bool DisableCaching { get; set; }
+}
@@ -0,0 +1,24 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Shared.DiagnosticIds;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// Abstract base class for skill sources. A skill source provides skills from a specific origin
+/// (filesystem, remote server, database, in-memory, etc.).
+/// </summary>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public abstract class AgentSkillsSource
+{
+    /// <summary>
+    /// Gets the skills provided by this source.
+    /// </summary>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A collection of skills from this source.</returns>
+    public abstract Task<IList<AgentSkill>> GetSkillsAsync(CancellationToken cancellationToken = default);
+}
@@ -0,0 +1,45 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// A skill source that aggregates multiple child sources, preserving their registration order.
+/// </summary>
+/// <remarks>
+/// Skills from each child source are returned in the order the sources were registered,
+/// with each source's skills appended sequentially. No deduplication or filtering is applied.
+/// </remarks>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+internal sealed class AggregatingAgentSkillsSource : AgentSkillsSource
+{
+    private readonly IEnumerable<AgentSkillsSource> _sources;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AggregatingAgentSkillsSource"/> class.
+    /// </summary>
+    /// <param name="sources">The child sources to aggregate.</param>
+    public AggregatingAgentSkillsSource(IEnumerable<AgentSkillsSource> sources)
+    {
+        this._sources = Throw.IfNull(sources);
+    }
+
+    /// <inheritdoc/>
+    public override async Task<IList<AgentSkill>> GetSkillsAsync(CancellationToken cancellationToken = default)
+    {
+        var allSkills = new List<AgentSkill>();
+        foreach (var source in this._sources)
+        {
+            var skills = await source.GetSkillsAsync(cancellationToken).ConfigureAwait(false);
+            allSkills.AddRange(skills);
+        }
+
+        return allSkills;
+    }
+}
@@ -0,0 +1,58 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Shared.DiagnosticIds;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// A skill source decorator that removes duplicate skills by name, keeping only the first occurrence.
+/// </summary>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+internal sealed partial class DeduplicatingAgentSkillsSource : DelegatingAgentSkillsSource
+{
+    private readonly ILogger<DeduplicatingAgentSkillsSource> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="DeduplicatingAgentSkillsSource"/> class.
+    /// </summary>
+    /// <param name="innerSource">The inner source to deduplicate.</param>
+    /// <param name="loggerFactory">Optional logger factory.</param>
+    public DeduplicatingAgentSkillsSource(AgentSkillsSource innerSource, ILoggerFactory? loggerFactory = null)
+        : base(innerSource)
+    {
+        this._logger = (loggerFactory ?? NullLoggerFactory.Instance).CreateLogger<DeduplicatingAgentSkillsSource>();
+    }
+
+    /// <inheritdoc/>
+    public override async Task<IList<AgentSkill>> GetSkillsAsync(CancellationToken cancellationToken = default)
+    {
+        var allSkills = await this.InnerSource.GetSkillsAsync(cancellationToken).ConfigureAwait(false);
+
+        var deduplicated = new List<AgentSkill>();
+        var seen = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+        foreach (var skill in allSkills)
+        {
+            if (seen.Add(skill.Frontmatter.Name))
+            {
+                deduplicated.Add(skill);
+            }
+            else
+            {
+                LogDuplicateSkillName(this._logger, skill.Frontmatter.Name);
+            }
+        }
+
+        return deduplicated;
+    }
+
+    [LoggerMessage(LogLevel.Warning, "Duplicate skill name '{SkillName}': subsequent skill skipped in favor of first occurrence")]
+    private static partial void LogDuplicateSkillName(ILogger logger, string skillName);
+}
@@ -0,0 +1,41 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// Provides an abstract base class for skill sources that delegate operations to an inner source
+/// while allowing for extensibility and customization.
+/// </summary>
+/// <remarks>
+/// <see cref="DelegatingAgentSkillsSource"/> implements the decorator pattern for <see cref="AgentSkillsSource"/>,
+/// enabling the creation of source pipelines where each layer can add functionality (caching, deduplication,
+/// filtering, etc.) while delegating core operations to an underlying source.
+/// </remarks>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+internal abstract class DelegatingAgentSkillsSource : AgentSkillsSource
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="DelegatingAgentSkillsSource"/> class with the specified inner source.
+    /// </summary>
+    /// <param name="innerSource">The underlying skill source that will handle the core operations.</param>
+    protected DelegatingAgentSkillsSource(AgentSkillsSource innerSource)
+    {
+        this.InnerSource = Throw.IfNull(innerSource);
+    }
+
+    /// <summary>
+    /// Gets the inner skill source that receives delegated operations.
+    /// </summary>
+    protected AgentSkillsSource InnerSource { get; }
+
+    /// <inheritdoc/>
+    public override Task<IList<AgentSkill>> GetSkillsAsync(CancellationToken cancellationToken = default)
+        => this.InnerSource.GetSkillsAsync(cancellationToken);
+}
@@ -0,0 +1,70 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// A skill source decorator that filters skills using a caller-supplied predicate.
+/// </summary>
+/// <remarks>
+/// Skills for which the predicate returns <see langword="true"/> are included in the result;
+/// skills for which it returns <see langword="false"/> are excluded and logged at debug level.
+/// </remarks>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+internal sealed partial class FilteringAgentSkillsSource : DelegatingAgentSkillsSource
+{
+    private readonly Func<AgentSkill, bool> _predicate;
+    private readonly ILogger<FilteringAgentSkillsSource> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="FilteringAgentSkillsSource"/> class.
+    /// </summary>
+    /// <param name="innerSource">The inner source whose skills will be filtered.</param>
+    /// <param name="predicate">
+    /// A predicate that determines which skills to include. Skills for which the predicate
+    /// returns <see langword="true"/> are kept; others are excluded.
+    /// </param>
+    /// <param name="loggerFactory">Optional logger factory.</param>
+    public FilteringAgentSkillsSource(
+        AgentSkillsSource innerSource,
+        Func<AgentSkill, bool> predicate,
+        ILoggerFactory? loggerFactory = null)
+        : base(innerSource)
+    {
+        this._predicate = Throw.IfNull(predicate);
+        this._logger = (loggerFactory ?? NullLoggerFactory.Instance).CreateLogger<FilteringAgentSkillsSource>();
+    }
+
+    /// <inheritdoc/>
+    public override async Task<IList<AgentSkill>> GetSkillsAsync(CancellationToken cancellationToken = default)
+    {
+        var allSkills = await this.InnerSource.GetSkillsAsync(cancellationToken).ConfigureAwait(false);
+
+        var filtered = new List<AgentSkill>();
+        foreach (var skill in allSkills)
+        {
+            if (this._predicate(skill))
+            {
+                filtered.Add(skill);
+            }
+            else
+            {
+                LogSkillFiltered(this._logger, skill.Frontmatter.Name);
+            }
+        }
+
+        return filtered;
+    }
+
+    [LoggerMessage(LogLevel.Debug, "Skill '{SkillName}' excluded by filter predicate")]
+    private static partial void LogSkillFiltered(ILogger logger, string skillName);
+}
@@ -0,0 +1,57 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// An <see cref="AgentSkill"/> discovered from a filesystem directory backed by a SKILL.md file.
+/// </summary>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public sealed class AgentFileSkill : AgentSkill
+{
+    private readonly IReadOnlyList<AgentSkillResource> _resources;
+    private readonly IReadOnlyList<AgentSkillScript> _scripts;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AgentFileSkill"/> class.
+    /// </summary>
+    /// <param name="frontmatter">The parsed frontmatter metadata for this skill.</param>
+    /// <param name="content">The full raw SKILL.md file content including YAML frontmatter.</param>
+    /// <param name="path">Absolute path to the directory containing this skill.</param>
+    /// <param name="resources">Resources discovered for this skill.</param>
+    /// <param name="scripts">Scripts discovered for this skill.</param>
+    internal AgentFileSkill(
+        AgentSkillFrontmatter frontmatter,
+        string content,
+        string path,
+        IReadOnlyList<AgentSkillResource>? resources = null,
+        IReadOnlyList<AgentSkillScript>? scripts = null)
+    {
+        this.Frontmatter = Throw.IfNull(frontmatter);
+        this.Content = Throw.IfNull(content);
+        this.Path = Throw.IfNullOrWhitespace(path);
+        this._resources = resources ?? [];
+        this._scripts = scripts ?? [];
+    }
+
+    /// <inheritdoc/>
+    public override AgentSkillFrontmatter Frontmatter { get; }
+
+    /// <inheritdoc/>
+    public override string Content { get; }
+
+    /// <summary>
+    /// Gets the directory path where the skill was discovered.
+    /// </summary>
+    public string Path { get; }
+
+    /// <inheritdoc/>
+    public override IReadOnlyList<AgentSkillResource> Resources => this._resources;
+
+    /// <inheritdoc/>
+    public override IReadOnlyList<AgentSkillScript> Scripts => this._scripts;
+}
@@ -0,0 +1,43 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.IO;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// A file-path-backed skill resource. Reads content from a file on disk relative to the skill directory.
+/// </summary>
+internal sealed class AgentFileSkillResource : AgentSkillResource
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AgentFileSkillResource"/> class.
+    /// </summary>
+    /// <param name="name">The resource name (relative path within the skill directory).</param>
+    /// <param name="fullPath">The absolute file path to the resource.</param>
+    public AgentFileSkillResource(string name, string fullPath)
+        : base(name)
+    {
+        this.FullPath = Throw.IfNullOrWhitespace(fullPath);
+    }
+
+    /// <summary>
+    /// Gets the absolute file path to the resource.
+    /// </summary>
+    public string FullPath { get; }
+
+    /// <inheritdoc/>
+    public override async Task<object?> ReadAsync(IServiceProvider? serviceProvider = null, CancellationToken cancellationToken = default)
+    {
+#if NET8_0_OR_GREATER
+        return await File.ReadAllTextAsync(this.FullPath, Encoding.UTF8, cancellationToken).ConfigureAwait(false);
+#else
+        using var reader = new StreamReader(this.FullPath, Encoding.UTF8);
+        return await reader.ReadToEndAsync().ConfigureAwait(false);
+#endif
+    }
+}
@@ -0,0 +1,56 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.AI;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
+
+namespace Microsoft.Agents.AI;
+
+/// <summary>
+/// A file-path-backed skill script. Represents a script file on disk that requires an external runner to run.
+/// </summary>
+[Experimental(DiagnosticIds.Experiments.AgentsAIExperiments)]
+public sealed class AgentFileSkillScript : AgentSkillScript
+{
+    private readonly AgentFileSkillScriptRunner? _runner;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AgentFileSkillScript"/> class.
+    /// </summary>
+    /// <param name="name">The script name.</param>
+    /// <param name="fullPath">The absolute file path to the script.</param>
+    /// <param name="runner">Optional external runner for running the script. An <see cref="InvalidOperationException"/> is thrown from <see cref="RunAsync"/> if no runner is provided.</param>
+    internal AgentFileSkillScript(string name, string fullPath, AgentFileSkillScriptRunner? runner = null)
+        : base(name)
+    {
+        this.FullPath = Throw.IfNullOrWhitespace(fullPath);
+        this._runner = runner;
+    }
+
+    /// <summary>
+    /// Gets the absolute file path to the script.
+    /// </summary>
+    public string FullPath { get; }
+
+    /// <inheritdoc/>
+    public override async Task<object?> RunAsync(AgentSkill skill, AIFunctionArguments arguments, CancellationToken cancellationToken = default)
+    {
+        if (skill is not AgentFileSkill fileSkill)
+        {
+            throw new InvalidOperationException($"File-based script '{this.Name}' requires an {nameof(AgentFileSkill)} but received '{skill.GetType().Name}'.");
+        }
+
+        if (this._runner is null)
+        {
+            throw new InvalidOperationException(
+                $"Script '{this.Name}' cannot be executed because no {nameof(AgentFileSkillScriptRunner)} was provided. " +
+                $"Supply a script runner when constructing {nameof(AgentFileSkillsSource)} to enable script execution.");
+        }
+
+        return await this._runner(fileSkill, this, arguments, cancellationToken).ConfigureAwait(false);
+    }
+}
--- a/Show More
+++ b/Show More