list_alerts ordered by created_at DESC alone; kpi_alerts has many rows sharing the same second timestamp (07:00 batches), so MySQL tie order is unstable and offset pagination both duplicated and skipped rows (entity 1 read-only probe: total=281, 281 rows walked, only 268 unique ids, 13 duplicates; id 587 unreachable in the unfiltered list while visible in ?status=pending).
Add secondary key id DESC so pages form a total order; add regression suite test_alerts_pagination_stability_20260925.py (tie-heavy fixture: unique==total, zero duplicates, strict id DESC inside a tie group, page concat == single-shot ordered query, unfiltered vs status-filtered visibility, entity isolation negative control).
