The rollup and the backup check in once, when they end, with the run's duration

A start and a finish sent seconds apart can reach Sentry in either order,
and a start that lands second is never closed, so a fast rollup was
reported as a timeout on nights it succeeded. Hnefatafl's monitor did so
nine nights in fifteen. One check-in at the end cannot race; a run that
hangs sends nothing and is marked missed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GwFKMuQnPAEHJ5yA1q4orh

template/deploy/__SLUG__-backup.sh

@@ -14,9 +14,14 @@ LOG="/var/log/__SLUG__/backup.log"
 STAMP=$(date +%Y-%m-%d)
 mkdir -p "$(dirname "$LOG")"
 CRON_URL=$(cat /root/.__SLUG__-sentry-cron 2>/dev/null || true)
+# One check-in, when the run ends, carrying its duration: a start and a
+# finish sent seconds apart can reach Sentry in either order, and a start
+# that lands second is never closed. A run that never ends sends nothing,
+# and Sentry marks the night missed.
+START=$SECONDS
 checkin() {
   [ -n "$CRON_URL" ] && curl -sf -o /dev/null -X POST -H "Content-Type: application/json" \
-    -d "{\"status\":\"$1\",\"monitor_config\":{\"schedule\":{\"type\":\"crontab\",\"value\":\"$SCHEDULE\"},\"checkin_margin\":30,\"max_runtime\":10,\"timezone\":\"UTC\"}}" \
+    -d "{\"status\":\"$1\",\"duration\":$((SECONDS - START)),\"monitor_config\":{\"schedule\":{\"type\":\"crontab\",\"value\":\"$SCHEDULE\"},\"checkin_margin\":30,\"max_runtime\":10,\"timezone\":\"UTC\"}}" \
     "$CRON_URL" || true
 }
 
@@ -27,7 +32,6 @@ fi
 
 {
   echo "=== $(date -Is) backup start"
-  checkin in_progress
   if rclone sync "$SRC" "spaces:$BUCKET/$PREFIX/current" --exclude 'rollup.jsonl' 2>&1 &&
      rclone copy "$SRC" "spaces:$BUCKET/$PREFIX/snapshots/$STAMP" 2>&1; then
     checkin ok