Files
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
History
..