Fix missing isolation kwarg on update_response in bg non-stream finalization

[RaviPidaparthi]

Problem

In _run_background_non_stream's finally block, the update_response call was missing the isolation= keyword argument. The _isolation variable was only computed inside the else branch (for create_response) but not used by the if branch (for update_response).

When isolation headers are present (x-agent-user-isolation-key / x-agent-chat-isolation-key), Foundry storage creates the response in a scoped partition at response.created time (FR-003). The finalization update_response without isolation headers then targets the unscoped partition, gets 404, the error is silently swallowed, and the record is evicted from memory. All subsequent GET polls hit Foundry's stale in_progress snapshot, leaving the response stuck permanently.

Affected path: background=True, stream=False, store=True with Foundry storage and isolation keys present.

Fix

Hoist the _isolation = context.isolation if context else None computation above the if/else branch so both update_response and create_response receive it.

Changes

• _orchestrator.py: Move _isolation computation before the if _provider_created: branch, add isolation=_isolation to update_response call
• test_bg_isolation_propagation.py (new): 3 contract tests using a recording provider that captures the isolation kwarg on every update_response call — verifies both keys, user-only key, and no-keys scenarios
• CHANGELOG.md: Bug fix entry for 1.0.0b2

[Copilot]

Pull request overview

Fixes a Foundry storage partitioning bug in the Responses background non-stream finalization path by ensuring the request’s isolation context is forwarded to the terminal update_response call, preventing stuck in_progress responses when isolation headers are present.

Changes:

• Hoists isolation context computation in _run_background_non_stream and passes isolation= into update_response.
• Adds contract tests to assert isolation propagation to update_response across header combinations.
• Documents the fix in the package changelog for 1.0.0b2.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/hosting/_orchestrator.py	Ensures background non-stream finalization update_response uses the same isolation context as create_response.
sdk/agentserver/azure-ai-agentserver-responses/tests/contract/test_bg_isolation_propagation.py	New regression/contract coverage verifying isolation is forwarded to update_response in bg non-stream mode.
sdk/agentserver/azure-ai-agentserver-responses/CHANGELOG.md	Adds a bug-fix entry describing the isolation propagation issue and impact.