Wesley pointed out (with a clean demo) that AsyncLocal<T> mutations made
inside an awaited async method do not leak back to the caller after the
method returns - the runtime restores the caller's view automatically.
ClientHeadersAgent.RunCoreAsync and RunCoreStreamingAsync are the only
callers of the scope, both are async methods awaited by their callers,
so the explicit using/Dispose pattern was doing work the runtime already
does for us.
* ClientHeadersScope collapsed to a single Current { get; set; } property
over an AsyncLocal<IReadOnlyDictionary<string,string>?>. Drops Push,
the Scope struct, and Dispose. XML doc explains the AsyncLocal natural-
restoration semantics so the design intent is self-documenting.
* ClientHeadersAgent uses a direct ClientHeadersScope.Current = snapshot
before delegating. Drops the local RunAsyncCoreAsync helper and the
snapshot-passed-as-parameter dance.
* Test 10 renamed to ClientHeadersScope_IsAsyncLocalIsolatedAndAutoRestoresAsync;
drops the LIFO claim, keeps the parallel-isolation assertion, and adds
a Wesley-style 'set inside async, caller sees null on return' assertion.
* Test 12 switches from using ClientHeadersScope.Push to direct
Current = ... with try/finally for test isolation.
Snapshot deep-copy in TrySnapshot stays - it defends against caller
mutating the source Dictionary mid-run, which is independent of the
AsyncLocal restoration mechanism.
* Bump MEAI to 10.5.1 and add per-call x-client header support
Replaces the brittle UserAgentResponsesClient subclass with a clean
per-call x-client-* header pipeline built on the new Microsoft.Extensions.AI
10.5.1 OpenAIRequestPolicies hook.
Public surface (Microsoft.Agents.AI.Foundry, [Experimental(MAAI001)]):
* chatOptions.WithClientHeader(name, value) and .WithClientHeaders(IEnumerable)
validate the x-client- prefix (case-insensitive), apply all-or-nothing on
bulk, and throw InvalidOperationException on foreign-typed slot collision
* myAgent.AsBuilder().UseClientHeaders().Build() opts a customer-built agent
into the pipeline; idempotent via agent.GetService<ClientHeadersAgent>()
* Foundry-built agents (FoundryAgent.Create*) pre-wire automatically
Internals:
* ClientHeadersAgent decorator snapshots the dict at scope-push time so
concurrent runs sharing a ChatOptions reference do not leak headers
* ClientHeadersScope is an AsyncLocal<IReadOnlyDictionary<string,string>?>
with LIFO push/dispose semantics
* ClientHeadersPolicy singleton stamps headers via Headers.Set so per-call
values overwrite any same-name header from earlier policies and so
duplicate registration is value-stable
* OpenAIRequestPoliciesReflection dedups against MEAI's private _entries
field and falls back to AddPolicy on any reflection failure; a CI test
asserts the field shape on every MEAI bump
Hosting cleanup:
* Deleted UserAgentResponsesClient and its dummy throwing pipeline
* HostedAgentUserAgentPolicy is now registered via OpenAIRequestPolicies
in FoundryHostingExtensions.TryApplyUserAgent
Tests:
* 19 new unit tests in ClientHeadersExtensionsTests.cs covering validation,
AsyncLocal isolation, snapshot semantics, end-to-end wire stamping, and
shared-chat-client dedup
* Updated OpenTelemetryAgentTests for MEAI 10.5.1 changes to web_search
serialization and the reduced tool definition payload when sensitive
data capture is disabled
Microsoft.Extensions.Compliance.Abstractions stays at 10.5.0 because no
10.5.1 release exists on nuget.org.
* Address PR review: pre-wire AsAIAgent path and dedup TryApplyUserAgent
* FoundryAgent: extract WireClientHeaders helper and call it from the
internal (AIProjectClient, ChatClientAgent) constructor used by
AzureAIProjectChatClientExtensions.AsAIAgent so those Foundry-built
agents also pre-wire the x-client header pipeline.
* Foundry.Hosting TryApplyUserAgent: dedup HostedAgentUserAgentPolicy
registration per OpenAIRequestPolicies instance via
ConditionalWeakTable so per-request resolution does not grow the
policy list unboundedly on singleton agents.
* Add tests covering AsAIAgent pre-wire and TryApplyUserAgent dedup
Backs the PR review fixes from a4c8f91 with regression tests:
* ClientHeadersExtensionsTests: AsAIAgent_FoundryAgent_HasPreWiredClientHeadersAgent
asserts the FoundryAgent built via AzureAIProjectChatClientExtensions.AsAIAgent
contains a ClientHeadersAgent in its delegating chain (catches future
regressions of the bypass).
* ClientHeadersExtensionsTests: FoundryAgent_PublicConstructor_HasPreWiredClientHeadersAgent
covers the public constructor path the same way.
* ClientHeadersExtensionsTests: UseClientHeaders_RepeatedRegistrations_OnSameChatClient_OnlyRegistersOnce
invokes UseClientHeaders 25 times on a shared chat client and asserts via
reflection that OpenAIRequestPolicies._entries length is exactly 1.
* HostedTryApplyUserAgentDedupTests: two tests asserting
FoundryHostingExtensions.TryApplyUserAgent stays at one entry per
OpenAIRequestPolicies instance after 50 calls on the same agent and across
distinct agents on different chat clients.
* Move tests next to their SUT
Removes the dedicated HostedTryApplyUserAgentDedupTests.cs test class.
Tests are co-located with the SUT they exercise:
* FoundryAgentTests.cs gains the Constructor_PreWiresClientHeadersAgent
and Constructor_FromAsAIAgentExtension_PreWiresClientHeadersAgent
cases, since FoundryAgent is the SUT for the pre-wire behavior.
* HostedOutboundUserAgentTests.cs gains the two TryApplyUserAgent dedup
cases, since FoundryHostingExtensions.TryApplyUserAgent is the SUT
it already covers.
* ClientHeadersExtensionsTests.cs keeps only the
UseClientHeaders_RepeatedRegistrations_OnSameChatClient_OnlyRegistersOnce
case, which exercises the public ClientHeadersExtensions surface.
* Remove redundant WithCancellation on inner streaming call
ct is already passed to InnerAgent.RunStreamingAsync, so
.WithCancellation(ct) on the resulting IAsyncEnumerable is a no-op.
Caught by Sergey on PR review.
* Address PR review: surface downstream MEAI experimental ID
* Add AIOpenAIRequestPolicies = MEAIExperiments alias to
DiagnosticIds.Experiments (matches the existing AIResponseContinuations,
AIMcpServers, AIFunctionApprovals pattern).
* Mark public ClientHeadersExtensions with [Experimental(AIOpenAIRequestPolicies)]
instead of AgentsAIExperiments. Consumers now see the MEAI001 warning,
surfacing the dependency on MEAI's experimental OpenAIRequestPolicies hook.
* Mark internal OpenAIRequestPoliciesReflection with the same alias to
suppress warnings at the source rather than via project-wide NoWarn.
* Remove MEAI001 from Foundry csproj NoWarn (kept on Foundry.Hosting where
pre-PR usages remain).
* Clarify ClientHeadersScope XML doc: AsyncLocal flows values forward but
does NOT auto-restore on method return; explicit using/Dispose is what
gives stack-style LIFO semantics.
Roger Barreto ·