- Introduced the `CollabGuestUiResult` type to distinguish between answers and unavailable states during guest UI requests.
- Updated the remote dialog race logic to ignore unavailable guest results and fallback to the local host dialog.
- Centralized the `FakeWebSocket` and `InMemoryRelay` test infrastructure into a shared test helpers file.
- Cleaned up duplicate mock implementations and updated existing test suites to utilize the shared in-memory relay helpers.
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