* .NET: Bump Azure.AI.AgentServer to 2.0.0 protocol and migrate Foundry.Hosting
Bumps Core .25->.26, Invocations .4->.5, Responses .5->.6 and adopts the 2.0.0 container protocol.
Breaking change: IsolationContext (UserIsolationKey + ChatIsolationKey) is replaced by PlatformContext (UserIdKey from x-agent-user-id, CallId from x-agent-foundry-call-id). The per-chat key is gone; HostedSessionContext is now user-only and the per-request CallId is forwarded outbound to Foundry first-party services (toolbox/MCP).
Also fixes a real call-id egress bug: AsyncLocal writes inside the streaming response iterator are reverted across yield boundaries, so the call id was dropped before the toolbox/MCP egress ran. The handler now re-applies HostedCallContext.CallId before each egress point.
Adds HostedConversationKey to map a request to a stable MAF AgentSession via conversation_id, else the partition key embedded in previous_response_id, else the minted response id. This keeps store=false previous_response_id chains and conversation_id forks on a single hosted MAF session without using the container session id.
Sample manifests bump the responses protocol to 2.0.0 (invocations stays 1.0.0). Integration tests split store/session semantics into HostedResponsesStoreConfigTests with its own scenario, read stored responses through the per-agent endpoint client, and inject the model deployment into the container.
* Pin Azure.Core 1.59.0 for Hosted-Workflow-Handoff sample
AgentServer 1.0.0-beta.26 (pulled transitively via Foundry.Hosting) requires Azure.Core 1.59.0. This sample disables transitive pinning and references Azure.Core directly, so override just this project to the SDK-required version without moving the solution-wide central pin.
* Add guard test for request-scoped call-id cleanup
Asserts HostedCallContext.CallId does not leak into the caller's execution context after CreateAsync's stream completes, while confirming the agent run still observed the call id. Documents the request-scoped contract and guards against stale-header leakage across requests handled on the same thread.
* Refresh hosting READMEs for AgentServer 2.0 migration
Updates stale docs to match the shipped code: the MemoryAgent README now describes the x-agent-user-id user-identity header (chat isolation key removed) feeding HostedSessionContext.UserId; the IntegrationTests README corrects the scenario count (six to eleven), adds the missing memory scenario row, and stops claiming all scenarios are skipped now that several are validated and active.
* Add ADR 0030 superseding 0026 for AgentServer 2.0 platform context
Documents the migration from ResponseContext.Isolation (UserIsolationKey/ChatIsolationKey) to ResponseContext.PlatformContext (UserIdKey/CallId): user-only HostedSessionContext, the request-scoped HostedCallContext call-id forwarded on egress, HostedConversationKey session keying, and removal of the PerChat/PerUserAndChat memory scopes. Marks ADR 0026 as superseded.
* Add breaking-change v2.0-only disclaimer to package metadata
Augments the package Description and adds PackageReleaseNotes stating this release targets the Foundry Responses container protocol v2.0 only, is not compatible with v1, and directs consumers to a previous release for the v1 protocol definition.
* Address review comments: dead chat-key surface and weak test assertions
Fixes the automated review findings: the MemoryAgent/AgentSkills .env.example now say one variable (only HOSTED_USER_ISOLATION_KEY remains); the MemoryAgent smoke script drops the unused ChatKey parameter and its call-site arguments; HostedConversationKey null test now exercises a real null (and whitespace); and the reuse-one-session test asserts an exact SessionCount of 1 instead of <= 1.
Roger Barreto
0d53d11bc6