[danshapiro]

Windows Codex recovery currently cannot confirm that the previous provider process tree has stopped, so it blocks recovery after a failed resume or provider exit. Guard each Windows provider with a Job Object and keep the session fenced until its processes are confirmed stopped. The same fence covers cancellation, handoff, attachment, and replayed create requests.

Update the browser recovery fixture to return the specific missing-session error and assert the current notice disclosure.

The guard remains conservative if it cannot account for a process. Durable cleanup across a full Freshell server crash remains a separate pre-existing limitation.

Validation:

• Native Windows: Job Object tests and 14 Codex recovery integration tests, including helper-process churn and cancellation and handoff races.
• Desktop workflows passed on Windows, Linux, and both macOS architectures for the implementation; the final follow-up changes only a browser assertion.
• Sandboxed Rust workspace tests, formatting, clippy, and TypeScript checks passed.
• Four affected cloud Chromium specs: 22 tests passed with retries disabled on the final commit.