Document explicitly that WriteBatchAsync never returns PermanentFail because the WriteAlarmEventsReply wire contract carries only a bool-per-event (no unrecoverable/transient distinction). Add a <remarks> XML block explaining the structural limitation, why poison events retry rather than dead-letter, and that a coordinated per-event status enum extension to the .NET 4.8 sidecar is a tracked follow-up. Add inline NOTE comments in both the success and catch paths for discoverability. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>