-- PR-B.3 (May 2026): Monitor.dedupWindowSeconds — per-monitor override
-- =========================================================
-- Until this column existed, every notification used the global
-- DEFAULT_DEDUP_WINDOW_SECONDS (300s). For monitors with non-typical
-- alerting cadence (e.g. an external SLA probe that needs faster
-- notification, or a chatty internal job that should be more
-- aggressively suppressed) operators had no knob.
--
-- NULL means "fall through to the default" — existing rows are
-- unaffected. The migration is reversible.

-- ============================================================
-- UP
-- ============================================================

ALTER TABLE `Monitor`
  ADD COLUMN `dedupWindowSeconds` INT NULL;

-- ============================================================
-- DOWN
-- ============================================================
-- Safe: column is nullable, no FK, only read by the dedup service.

ALTER TABLE `Monitor`
  DROP COLUMN `dedupWindowSeconds`;