.NET: [BREAKING] Rename to AgentIsolationKeyProvider

[SergeyMenshykh]

Motivation & Context

SessionIsolationKeyProvider is consumed by both IsolationKeyScopedAgentSessionStore and A2A's IsolationKeyScopedTaskStore, partitioning persisted sessions, tasks, and context IDs. The session-specific name is therefore misleading.

Description & Review Guide

• What are the major changes? Rename the shared provider and related claims-based APIs to AgentIsolationKeyProvider / ClaimsIdentityAgentIsolationKeyProvider / UseClaimsBasedAgentIsolation, and shorten the abstract method to GetIsolationKeyAsync. Consumers, tests, samples, and docs are updated.
• What is the impact of these changes? Source-breaking API rename with no behavioral change.
• What do you want reviewers to focus on? Whether the Agent prefix reads correctly. It marks the hosting API domain and disambiguates from generic isolation-key abstractions in other libraries; it does not mean agent instances are isolated. Dropping Store leaves room for future non-store isolation such as memory or retrieval. The XML docs state this explicitly.

Related Issue

No related issue; no other open PR was found for this rename.

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

[Copilot]

Pull request overview

Renames the .NET isolation-key API from session-specific terminology to store-wide terminology, covering session and A2A task persistence without behavioral changes.

Changes:

• Renames providers, options, methods, and DI extensions to StoreIsolation.
• Updates hosting integrations and tests.
• Updates samples and documentation.

Reviewed changes

Copilot reviewed 29 out of 29 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
dotnet/tests/Microsoft.Agents.AI.Hosting.UnitTests/StoreIsolationKeyProviderTests.cs	Updates provider contract tests.
dotnet/tests/Microsoft.Agents.AI.Hosting.UnitTests/IsolationKeyScopedAgentSessionStoreTests.cs	Updates session-store tests and messages.
dotnet/tests/Microsoft.Agents.AI.Hosting.UnitTests/ClaimsIdentityStoreIsolationKeyProviderTests.cs	Updates claims-provider tests.
dotnet/tests/Microsoft.Agents.AI.Hosting.A2A.UnitTests/IsolationKeyScopedTaskStoreTests.cs	Updates task-store provider mocks.
dotnet/tests/Microsoft.Agents.AI.Hosting.A2A.UnitTests/A2AServerServiceCollectionExtensionsTests.cs	Updates A2A DI tests.
dotnet/src/Microsoft.Agents.AI.Hosting/StoreIsolationKeyProvider.cs	Renames the core provider API.
dotnet/src/Microsoft.Agents.AI.Hosting/Local/InMemoryAgentSessionStore.cs	Updates isolation guidance.
dotnet/src/Microsoft.Agents.AI.Hosting/IsolationKeyScopedAgentSessionStoreOptions.cs	Updates API references.
dotnet/src/Microsoft.Agents.AI.Hosting/IsolationKeyScopedAgentSessionStore.cs	Consumes the renamed provider.
dotnet/src/Microsoft.Agents.AI.Hosting/HostedAgentBuilderExtensions.cs	Resolves the renamed DI service.
dotnet/src/Microsoft.Agents.AI.Hosting/AgentSessionStore.cs	Updates trust-model documentation.
dotnet/src/Microsoft.Agents.AI.Hosting.AspNetCore/ServiceCollectionExtensions.cs	Renames claims-based registration API.
dotnet/src/Microsoft.Agents.AI.Hosting.AspNetCore/ClaimsIdentityStoreIsolationKeyProviderOptions.cs	Renames claims-provider options.
dotnet/src/Microsoft.Agents.AI.Hosting.AspNetCore/ClaimsIdentityStoreIsolationKeyProvider.cs	Renames the claims-based provider.
dotnet/src/Microsoft.Agents.AI.Hosting.AGUI.AspNetCore/AGUIEndpointRouteBuilderExtensions.cs	Updates AG-UI integration.
dotnet/src/Microsoft.Agents.AI.Hosting.A2A/IsolationKeyScopedTaskStore.cs	Updates A2A task isolation.
dotnet/src/Microsoft.Agents.AI.Hosting.A2A/A2AServerServiceCollectionExtensions.cs	Updates A2A registration and guidance.
dotnet/samples/05-end-to-end/AGUIWebChat/Server/Program.cs	Updates sample guidance.
dotnet/samples/05-end-to-end/AGUIClientServer/AGUIServer/Program.cs	Updates sample guidance.
dotnet/samples/05-end-to-end/AGUIClientServer/AGUIDojoServer/Program.cs	Updates sample guidance.
dotnet/samples/05-end-to-end/AgentWebChat/AgentWebChat.AgentHost/Program.cs	Updates isolation examples.
dotnet/samples/05-end-to-end/A2AClientServer/A2AServer/Program.cs	Updates isolation examples.
dotnet/samples/02-agents/AGUI/Step05_StateManagement/Server/Program.cs	Updates sample guidance.
dotnet/samples/02-agents/AGUI/Step04_HumanInLoop/Server/Program.cs	Updates sample guidance.
dotnet/samples/02-agents/AGUI/Step03_FrontendTools/Server/Program.cs	Updates sample guidance.
dotnet/samples/02-agents/AGUI/Step02_BackendTools/Server/Program.cs	Updates sample guidance.
dotnet/samples/02-agents/AGUI/Step01_GettingStarted/Server/Program.cs	Updates sample guidance.
dotnet/samples/02-agents/AGUI/README.md	Updates documented API name.
docs/specs/003-dotnet-hosting-protocol-helpers.md	Updates specification guidance.

[github-actions]

Agent Framework Review — Iteration 1

Completed passes: 5 | Result: No high-severity findings

Scope: full PR (2 commit(s)): c0ff8a64ef65, 86f9f8d13279

Review passes

• Correctness (gpt-5.6-sol) — No issues found in this pass.
• Security Reliability (claude-opus-4.8) — No issues found in this pass.
• Test Coverage (gpt-5.6-sol) — No issues found in this pass.
• Failure Modes (claude-opus-4.8) — No issues found in this pass.
• Design Approach (claude-opus-4.8) — No issues found in this pass.