Fix early reminder notifications and lost recovery notifications

- AlertState.update() now resets last_notification when the alert level
  changes, so a WARNING→CRITICAL escalation restarts the reminder interval
  rather than inheriting a nearly-expired timer.
- _dispatch_to_channel() bypasses min_level for RECOVER, so recovery
  notifications are delivered even after a server restart when
  _alerted_channels is empty and the fallback dispatch path is used.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hbd/server/notify.py

@@ -385,11 +385,18 @@ _DRIVERS = {
 
 
 def _dispatch_to_channel(channel_name: str, channel_cfg: dict, notif: Notification) -> bool:
-    """Send *notif* to a single named channel, honouring min_level."""
+    """Send *notif* to a single named channel, honouring min_level.
+
+    RECOVER always bypasses min_level — a recovery is always relevant if the
+    channel was configured for any alerting (handles the restart-then-recover case
+    where _alerted_channels is empty and we fall through to the normal loop).
+    """
+    level = notif.level.upper()
+    if level != "RECOVER":
         min_level = channel_cfg.get("min_level", "WARNING").upper()
-    if _level_value(notif.level) < _level_value(min_level):
+        if _level_value(level) < _level_value(min_level):
             logger.debug(
-            "channel '%s': skipping level %s (min_level=%s)", channel_name, notif.level, min_level
+                "channel '%s': skipping level %s (min_level=%s)", channel_name, level, min_level
             )
             return True  # not an error — filtered intentionally
 

hbd/server/threshold.py

@@ -105,6 +105,7 @@ class AlertState:
             self.level = level
             self.since = now
             self.notification_count = 0
+            self.last_notification = None  # restart reminder interval on level change
             # Reset acknowledgment on state change
             if level != AlertLevel.OK:
                 # Only reset if changing to a different alert level