fix(jobs): compare the escalation and reminder cut-offs in UTC

created_at holds UTC — ClockService::now() is deliberately UTC, because
a timestamp records an instant rather than a day. The escalation and
reminder jobs, equally deliberately, work their cut-offs out on the
server's calendar: which day a request falls on is a company question.

Formatting such a cut-off straight into the query wrote its local
wall-clock and silently shifted every bound by the server's UTC offset.
Escalation only slipped by hours, but the reminder band is exactly one
working day wide, so off Berlin's or Auckland's offset it reminded a
cohort a day early or skipped it altogether.

Converted in the mapper, which is the layer that knows what the column
holds, so both queries are covered at once. Rebuilt from the timestamp
rather than via setTimezone() so a caller's mutable DateTime is never
altered underneath it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Frank Karlitschek

lib/Db/LeaveRequestMapper.php

@@ -105,6 +105,26 @@ public function findEscalated(): array {
 		return $this->findEntities($qb);
 	}
 
+	/**
+	 * Render an instant the way `created_at` is stored.
+	 *
+	 * The timestamp columns hold UTC ({@see \OCA\Absence\Service\ClockService::now()}),
+	 * but the callers of the two queries below work out their cut-offs on the
+	 * *server's* calendar — which day boundary a request falls on is a company
+	 * question, not a UTC one. Formatting such a cut-off directly would write its
+	 * local wall-clock into the query and silently shift every bound by the
+	 * server's UTC offset: the reminder window is exactly one working day wide, so
+	 * off Berlin's or Auckland's offset it reminds a day early or skips a cohort
+	 * entirely. Converting here keeps the working-day arithmetic on the server's
+	 * calendar while the comparison happens in the column's own zone.
+	 *
+	 * Rebuilt from the timestamp rather than via setTimezone() so a caller's
+	 * mutable \DateTime is never altered as a side effect.
+	 */
+	private function asStoredTimestamp(\DateTimeInterface $moment): string {
+		return (new \DateTimeImmutable('@' . $moment->getTimestamp()))->format('Y-m-d H:i:s');
+	}
+
 	/**
 	 * Pending requests created before the given cut-off (for escalation/reminders).
 	 *
@@ -117,7 +137,7 @@ public function findPendingOlderThan(\DateTimeInterface $cutoff): array {
 			->where($qb->expr()->eq('status', $qb->createNamedParameter(LeaveRequest::STATUS_PENDING)))
 			->andWhere($qb->expr()->isNotNull('manager_uid'))
 			->andWhere($qb->expr()->lt('created_at', $qb->createNamedParameter(
-				$cutoff->format('Y-m-d H:i:s'), IQueryBuilder::PARAM_STR)));
+				$this->asStoredTimestamp($cutoff), IQueryBuilder::PARAM_STR)));
 		return $this->findEntities($qb);
 	}
 
@@ -170,8 +190,8 @@ public function findPendingCreatedBetween(\DateTimeInterface $after, \DateTimeIn
 			->from($this->getTableName())
 			->where($qb->expr()->eq('status', $qb->createNamedParameter(LeaveRequest::STATUS_PENDING)))
 			->andWhere($qb->expr()->isNotNull('manager_uid'))
-			->andWhere($qb->expr()->lt('created_at', $qb->createNamedParameter($before->format('Y-m-d H:i:s'), IQueryBuilder::PARAM_STR)))
-			->andWhere($qb->expr()->gte('created_at', $qb->createNamedParameter($after->format('Y-m-d H:i:s'), IQueryBuilder::PARAM_STR)));
+			->andWhere($qb->expr()->lt('created_at', $qb->createNamedParameter($this->asStoredTimestamp($before), IQueryBuilder::PARAM_STR)))
+			->andWhere($qb->expr()->gte('created_at', $qb->createNamedParameter($this->asStoredTimestamp($after), IQueryBuilder::PARAM_STR)));
 		return $this->findEntities($qb);
 	}