{
  "overall_correctness": "correct",
  "explanation": "PASS. `blockSessionChange` now cancels switches and branches unconditionally, including while fatal teardown is awaiting the shared custody outcome, and `testFatalTeardownAwaitsInFlightOutcome` executes that interleaving. `teardownSession` keeps one promise across the internal bounded `endSessionWithRetry` loop, so a concurrent fatal close and `session_shutdown` join the same transient failure, timer, and successful retry as exercised by `testSessionEndRetriesAfterTransientFailure`; retry waits remain event-loop-ref'ed, and exhaustion performs exactly the initial attempt plus one attempt per configured delay before propagating without leaving a timer. No replacement P1/P2 race was found in the scoped code.",
  "confidence": 0.98
}