Ben Thomas 6cd81286a9 .NET: dotnet: Add hosted-agent User-Agent supplement to outgoing requests (#5453)
* dotnet: Add hosted-agent User-Agent supplement to outgoing requests

When an agent runs inside a Foundry Hosted Agent, the outgoing
User-Agent header now includes 'agent-framework-hosted/{version}'
alongside the existing 'MEAI/{version}' segment.

- Add HostedAgentContext with AsyncLocal<string?> property
- MeaiUserAgentPolicy reads the supplement per-call
- AgentFrameworkResponseHandler sets/restores the context

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* chore: update hosted UA format to foundry-hosting/agent-framework-dotnet/{version}

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Trying to get UA flowing, no luck yet.

* .NET: Polyfill MEAI OpenAIResponsesChatClient to add hosted-agent User-Agent supplement

When AgentFrameworkResponseHandler resolves an agent (i.e. we are running in a
hosted context), TryApplyUserAgent walks the agent's IChatClient decorator chain
to find MEAI's internal OpenAIResponsesChatClient and reflectively swaps its
inner _responseClient field with a DelegatingResponsesClient wrapper. The
wrapper overrides the public-virtual protocol methods to add a per-call
HostedAgentUserAgentPolicy to the RequestOptions and delegate to the inner
ResponsesClient. The OpenAI SDK's internal streaming overloads bottom out in
calls to the public-virtual non-streaming overloads via virtual dispatch on
this, so streaming is covered without overriding any non-virtual member.

The wrapper accepts any ResponsesClient-derived inner — both the Foundry
ProjectResponsesClient and the native OpenAI ResponsesClient — and preserves
the inner client's full pipeline (Transport, RetryPolicy, NetworkTimeout,
OrganizationId / ProjectId / UserAgentApplicationId, custom policies).

- Add DelegatingResponsesClient + HostedAgentUserAgentPolicy in Microsoft.Agents.AI.Foundry.Hosting.
- Add TryApplyUserAgent next to ApplyOpenTelemetry in FoundryHostingExtensions; wire it into AgentFrameworkResponseHandler.GetAgent for both keyed and default-agent paths.
- Drop earlier-iteration dead code: AddHostedAgentTelemetry extension, HostedUserAgentPolicy class, HostedAgentContext.cs, and the never-called ToRequestOptions helper.
- Revert RequestOptionsExtensions.MeaiUserAgentPolicy to MEAI-only (the supplement is now injected by the polyfill).
- Revert unrelated whitespace change in Agent_Step25_ToolboxServerSideTools sample.
- Tests cover streaming AND non-streaming, retry policy preservation, OrganizationId/ProjectId/UserAgentApplicationId pass-through, idempotency, native OpenAI ResponsesClient, and reflection guards for MEAI/OpenAI shape drift.

* .NET: Address review feedback on hosted-agent User-Agent polyfill

- TryApplyUserAgent: replace silent null-return with ArgumentNullException to match the codebase's convention.
- Add idempotency test (TryApplyUserAgent_CalledTwiceOnSameAgent_DoesNotDoubleWrap) — runs the polyfill twice on the same agent and asserts the wire UA contains exactly one foundry-hosting segment, proving the 'current is DelegatingResponsesClient' guard prevents nested wrapping.
- Add retry-double-append test (Polyfill_RetryWithinCall_DoesNotDuplicateSupplementInUserAgent) — exercises the HostedAgentUserAgentPolicy Contains-guard via a custom retry policy that re-runs the inner pipeline on the same message.
- Replace TryApplyUserAgent_NullAgent_ReturnsNullWithoutThrowing with TryApplyUserAgent_NullAgent_ThrowsArgumentNullException to match the new contract.

* .NET: Drop null check from TryApplyUserAgent and its now-redundant test

The two call sites in AgentFrameworkResponseHandler.GetAgent already null-check the agent before invoking TryApplyUserAgent, so the defensive ArgumentNullException is unreachable. Remove it and the corresponding test.

* .NET: Remove unused Microsoft.Shared.Diagnostics import in ServiceCollectionExtensions

The Throw.IfNull helper from this namespace was used by the now-removed null check in TryApplyUserAgent. Drop the unused import to satisfy IDE0005 in CI's full-project dotnet format run.

---------

Co-authored-by: alliscode <bentho@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Roger Barreto <19890735+rogerbarreto@users.noreply.github.com>
6cd81286a9 · 2026-04-30 16:37:54 +00:00
1,985 Commits
2025-10-30 20:29:01 +00:00
2025-04-28 12:54:43 -07:00
2025-04-28 12:54:42 -07:00

Microsoft Agent Framework

Welcome to Microsoft Agent Framework!

Microsoft Foundry Discord MS Learn Documentation PyPI NuGet

Welcome to Microsoft's comprehensive multi-language framework for building, orchestrating, and deploying AI agents with support for both .NET and Python implementations. This framework provides everything from simple chat agents to complex multi-agent workflows with graph-based orchestration.

Watch the full Agent Framework introduction (30 min)

Watch the full Agent Framework introduction (30 min)

📋 Getting Started

📦 Installation

Python

pip install agent-framework
# This will install all sub-packages, see `python/packages` for individual packages.
# It may take a minute on first install on Windows.

.NET

dotnet add package Microsoft.Agents.AI

📚 Documentation

Still have questions? Join our weekly office hours or ask questions in our Discord channel to get help from the team and other users.

Highlights

  • Graph-based Workflows: Connect agents and deterministic functions using data flows with streaming, checkpointing, human-in-the-loop, and time-travel capabilities
  • AF Labs: Experimental packages for cutting-edge features including benchmarking, reinforcement learning, and research initiatives
  • DevUI: Interactive developer UI for agent development, testing, and debugging workflows

See the DevUI in action

See the DevUI in action (1 min)

💬 We want your feedback!

Quickstart

Basic Agent - Python

Create a simple Azure Responses Agent that writes a haiku about the Microsoft Agent Framework

# pip install agent-framework
# Use `az login` to authenticate with Azure CLI
import os
import asyncio
from agent_framework import Agent
from agent_framework.foundry import FoundryChatClient
from azure.identity import AzureCliCredential


async def main():
    # Initialize a chat agent with Microsoft Foundry
    # the endpoint, deployment name, and api version can be set via environment variables
    # or they can be passed in directly to the FoundryChatClient constructor
    agent = Agent(
      client=FoundryChatClient(
          credential=AzureCliCredential(),
          # project_endpoint=os.environ["FOUNDRY_PROJECT_ENDPOINT"],
          # model=os.environ["FOUNDRY_MODEL_DEPLOYMENT_NAME"],
      ),
      name="HaikuBot",
      instructions="You are an upbeat assistant that writes beautifully.",
    )

    print(await agent.run("Write a haiku about Microsoft Agent Framework."))

if __name__ == "__main__":
    asyncio.run(main())

Basic Agent - .NET

Create a simple Agent, using Microsoft Foundry with token-based auth, that writes a haiku about the Microsoft Agent Framework

// dotnet add package Microsoft.Agents.AI.Foundry
// Use `az login` to authenticate with Azure CLI
using Azure.AI.Projects;
using Azure.Identity;
using System;
using Azure.AI.Projects;
using Azure.Identity;

var endpoint = Environment.GetEnvironmentVariable("AZURE_AI_PROJECT_ENDPOINT") ?? throw new InvalidOperationException("AZURE_AI_PROJECT_ENDPOINT is not set.");
var deploymentName = Environment.GetEnvironmentVariable("AZURE_AI_MODEL_DEPLOYMENT_NAME") ?? "gpt-5.4-mini";

var agent = new AIProjectClient(new Uri(endpoint), new DefaultAzureCredential())
    .AsAIAgent(model: deploymentName, name: "HaikuBot", instructions: "You are an upbeat assistant that writes beautifully.");

Console.WriteLine(await agent.RunAsync("Write a haiku about Microsoft Agent Framework."));

Create a simple Agent, using OpenAI Responses, that writes a haiku about the Microsoft Agent Framework

// dotnet add package Microsoft.Agents.AI.OpenAI
using System;
using OpenAI;
using OpenAI.Responses;

// Replace the <apikey> with your OpenAI API key.
var agent = new OpenAIClient("<apikey>")
    .GetResponsesClient()
    .AsAIAgent(model: "gpt-5.4-mini", name: "HaikuBot", instructions: "You are an upbeat assistant that writes beautifully.");

Console.WriteLine(await agent.RunAsync("Write a haiku about Microsoft Agent Framework."));

More Examples & Samples

Python

  • Getting Started: progressive tutorial from hello-world to hosting
  • Agent Concepts: deep-dive samples by topic (tools, middleware, providers, etc.)
  • Workflows: workflow creation and integration with agents
  • Hosting: A2A, Azure Functions, Durable Task hosting
  • End-to-End: full applications, evaluation, and demos

.NET

Troubleshooting

Authentication

Problem Cause Fix
Authentication errors when using Azure credentials Not signed in to Azure CLI Run az login before starting your app
API key errors Wrong or missing API key Verify the key and ensure it's for the correct resource/provider

Tip: DefaultAzureCredential is convenient for development but in production, consider using a specific credential (e.g., ManagedIdentityCredential) to avoid latency issues, unintended credential probing, and potential security risks from fallback mechanisms.

Environment Variables

The samples typically read configuration from environment variables. Common required variables:

Variable Used by Purpose
AZURE_OPENAI_ENDPOINT Azure OpenAI samples Your Azure OpenAI resource URL
AZURE_OPENAI_DEPLOYMENT_NAME Azure OpenAI samples Model deployment name (e.g. gpt-4o-mini)
AZURE_AI_PROJECT_ENDPOINT Microsoft Foundry samples Your Microsoft Foundry project endpoint
AZURE_AI_MODEL_DEPLOYMENT_NAME Microsoft Foundry samples Model deployment name
OPENAI_API_KEY OpenAI (non-Azure) samples Your OpenAI platform API key

Contributor Resources

Important Notes

Important

If you use Microsoft Agent Framework to build applications that operate with any third-party servers, agents, code, or non-Azure Direct models (“Third-Party Systems”), you do so at your own risk. Third-Party Systems are Non-Microsoft Products under the Microsoft Product Terms and are governed by their own third-party license terms. You are responsible for any usage and associated costs.

We recommend reviewing all data being shared with and received from Third-Party Systems and being cognizant of third-party practices for handling, sharing, retention and location of data. It is your responsibility to manage whether your data will flow outside of your organizations Azure compliance and geographic boundaries and any related implications, and that appropriate permissions, boundaries and approvals are provisioned.

You are responsible for carefully reviewing and testing applications you build using Microsoft Agent Framework in the context of your specific use cases, and making all appropriate decisions and customizations. This includes implementing your own responsible AI mitigations such as metaprompt, content filters, or other safety systems, and ensuring your applications meet appropriate quality, reliability, security, and trustworthiness standards. See also: Transparency FAQ

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