epics2sms: only send RESOLVED if an alarm message was sent this episode

Guard the recovery notification on msg_count > 0, so a brief excursion that
never produced an alarm message (e.g. recovered before any send, or all
sends failed) does not emit a lone RESOLVED. Recovery is still logged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

EPICS2SMS.sh

@@ -183,12 +183,15 @@ monitor_loop() {
     else
       if (( in_alarm )); then
         mlog "$tag" "recovered to normal (avg=$avg) after $msg_count message(s)"
-        # Recovery notification: sent once, immediately (not throttled/capped).
-        body="RESOLVED: $text - now avg=$avg (last=$value) $(date '+%F %T')"
-        if send_alert "$body" "EPICS resolved"; then
-          mlog "$tag" "resolve notification sent"
-        else
-          mlog "$tag" "ERROR: resolve notification failed to send"
+        # Recovery notification: only if we actually alerted during this
+        # episode; sent once, immediately (not throttled/capped).
+        if (( msg_count > 0 )); then
+          body="RESOLVED: $text - now avg=$avg (last=$value) $(date '+%F %T')"
+          if send_alert "$body" "EPICS resolved"; then
+            mlog "$tag" "resolve notification sent"
+          else
+            mlog "$tag" "ERROR: resolve notification failed to send"
+          fi
         fi
       fi
       in_alarm=0

README.md

@@ -63,8 +63,9 @@ Behaviour of one monitor:
 - while the average is in alarm, sends the first message immediately, then up
   to `n_msg` messages total, spaced at least `msg_delay_s` apart, then stays
   silent
-- once the average returns to normal, it sends **one** recovery ("RESOLVED")
-  message and resets the message counter
+- once the average returns to normal, it resets the message counter and — if
+  at least one alarm message was sent this episode — sends **one** recovery
+  ("RESOLVED") message
 - unreadable / non-numeric reads are logged and skipped (they do not enter the
   average and never trigger an alarm)