The system ran two independent next-occurrence engines: Dart computes proximaProgramable (what the UI shows) and sends it as triggerAtMillis, but the native scheduleAlarm discarded it and recomputed from hour/minute/weekdays. Two engines over the same data WILL diverge — observed on-device: Dart said "today 22:48", the native weekday scan armed next Friday, and the alarm silently never rang at its hour while snooze (which bypasses recomputation and obeys a timestamp) always worked. That asymmetry was the user-visible "saving an alarm breaks, snoozing works" split. Fresh channel calls now arm exactly the trigger Dart sent whenever it is in the future or within the shared 90s imminence window; the native recompute remains as the fallback for stale triggers and for autonomous re-arms with no fresh Dart data (onAlarmFired's next occurrence, boot/persisted reschedules). Snooze preservation is untouched: a live native snooze still short-circuits through the compute path. Also logs the weekdays/trigger/lastHandled payload on every schedule call so day-convention divergences are diagnosable from logcat.