.NET: Align Microsoft.Agents.AI.Foundry.Hosting experimental flags to MAAI001 for MAF-specific APIs

[rogerbarreto]

Summary

Microsoft.Agents.AI.Foundry.Hosting is inconsistent in which [Experimental(...)] diagnostic id it applies to its public APIs. Most types use DiagnosticIds.Experiments.AIOpenAIResponses (OPENAI001), while a few MAF-specific types use DiagnosticIds.Experiments.AgentsAIExperiments (MAAI001) — e.g. FoundryToolboxHealthCheck, FoundryToolboxStartupStatus, and (added in #6718) UserToolboxConsent / FoundryToolboxService.GetUserToolboxConsents.

The MAF-specific public surface should consistently use MAAI001, not OPENAI001.

Rationale

• OPENAI001 exists to mirror the OpenAI package's experimental diagnostic, so consumers using experimental OpenAI APIs don't need an extra suppression (per the comments in dotnet/src/Shared/DiagnosticIds/DiagnosticsIds.cs). It is appropriate only for APIs that surface OpenAI experimental types.
• The AgentServer base types this package builds on — Azure.AI.AgentServer.Responses.ResponseHandler and ResponseContext — are not marked [Experimental] (verified against Azure.AI.AgentServer.Responses 1.0.0-beta.5).
• None of the package's public types expose OpenAI experimental types in their signatures; they are MAF hosting/agent abstractions. So OPENAI001 is a legacy/copy-paste inconsistency and MAAI001 is the correct id.

Proposed change

Switch the remaining MAF-specific [Experimental(DiagnosticIds.Experiments.AIOpenAIResponses)] usages in Microsoft.Agents.AI.Foundry.Hosting to DiagnosticIds.Experiments.AgentsAIExperiments (MAAI001):

• AgentFrameworkResponseHandler.cs
• AgentSessionStore.cs
• FileSystemAgentSessionStore.cs
• InMemoryAgentSessionStore.cs
• FoundryAIToolExtensions.cs
• FoundryToolboxService.cs (class-level)
• FoundryToolboxOptions.cs
• HostedSessionContext.cs
• HostedSessionContextExtensions.cs
• HostedSessionIsolationKeyProvider.cs
• PlatformHostedSessionIsolationKeyProvider.cs
• HostedSessionJsonUtilities.cs (2 usages)
• HostedFoundryMemoryProviderScopes.cs
• HostedFoundryMemoryProviderServiceCollectionExtensions.cs
• ServiceCollectionExtensions.cs

Audit each public type before flipping: keep OPENAI001 only where a type genuinely exposes an OpenAI experimental type in its public surface (none found so far).

Notes / risk

• Build-safe. MAAI001 is already globally suppressed in dotnet/tests/Directory.Build.props and dotnet/samples/Directory.Build.props, so consuming tests and samples keep compiling.
• The package is pre-release (VersionSuffix=preview, package validation disabled), so changing experimental diagnostic ids carries no compatibility concern.

Acceptance criteria

• All MAF-specific public APIs in Microsoft.Agents.AI.Foundry.Hosting use MAAI001 (or a justified OPENAI001/MEAI001 where an external experimental type is genuinely surfaced).
• dotnet build and unit tests pass for the package and its consumers (tests, samples, integration test container).

Context

Discovered during review of #6718 (Foundry hosted-agent toolbox OAuth consent). The new consent API was already corrected to MAAI001 in that PR; this issue tracks the broader package alignment as a separate change.