An alert that resolved while its firing notification was still in the
grouping window or waiting in the persistent queue (alert delay pushes
activation close to resolution; quiet-hours replay defers delivery)
produced a recovery-only notification: CancelAlert dropped the queued
firing, but LastNotified had been set optimistically at dispatch, so
the resolved-notification gate believed the firing had been sent.
CancelAlert now reports whether it cancelled a firing notification that
had not been delivered (grouping window entries and pending queue rows;
mid-send rows are excluded because their delivery may still complete),
and handleAlertResolved suppresses the recovery in that case. This also
covers the quiet-hours replay bypass: a recovery only follows a deferred
firing if the replay was actually delivered.
Addresses #1553
Fixed deadlock where CancelByAlertIDs held nq.mu.Lock() and then called
UpdateStatus() which also tried to acquire the same lock. Now uses
direct SQL while holding the lock.
Tests added for CancelByAlertIDs:
- No matching notifications (notification stays pending)
- Matching notification cancelled
- Multiple alerts with partial match (any match cancels)
Coverage: CancelByAlertIDs 65.7% -> 81.1%
Test coverage for calculateBackoff (exponential backoff calculation),
NotificationQueueStatus constants, and QueuedNotification struct fields.
15 test cases covering backoff timing, cap behavior, and struct defaults.
