[WhaleTech (ryo-whaletech)]

Motivation & Context

Foundry Hosting tests exercise local AgentServer-backed persistence. Independent pytest execution contexts can share its JSON state root, allowing one test's write to remove another test's response-chain session.

Description & Review Guide

• What are the major changes? A package-local function-scoped fixture gives each Foundry Hosting test a state root under its pytest temporary directory and restores the previous environment afterward. A deterministic regression in the existing state-store test file checks the test-local root contract.
• What is the impact of these changes? Unrelated tests within and across workers no longer share local AgentServer files. Requests within one test still share its root, and tests or child processes can explicitly choose a common root for persistence and restart scenarios. Production code, storage formats, APIs, and errors are unchanged.
• What do you want reviewers to focus on? The per-test fixture boundary and the ability to opt into a deliberate shared root.

Related Issue

Fixes #8408

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]

🟢 Approval recommended

The fixture provides function-scoped isolation while preserving explicit root overrides and automatic environment restoration.

Pull request overview

Isolates Foundry Hosting test persistence to prevent cross-test and cross-worker state interference.

Changes:

• Adds an autouse fixture assigning each test a temporary AgentServer state root.
• Adds a regression test verifying the root is test-scoped.

File summaries

File	Description
python/packages/foundry_hosting/tests/conftest.py	Configures per-test local state isolation.
python/packages/foundry_hosting/tests/test_state_store.py	Verifies the isolated state-root contract.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Balanced

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[Eduard van Valkenburg (eavanvalkenburg)]

Reviewed the complete diff and found no actionable issues. All reported checks for the current head are green.