-- +goose Up
-- Add the fourth watch loop trigger type, collision, to the alerts.alert_type closed set. Cross opportunity
-- collision deconfliction flags when a candidate (most sharply a scarce cleared one) is proposed or approved on
-- the slates of two or more DISTINCT competing OPEN opportunities at once, so a capture team never quietly
-- double commits the same scarce cleared person across competing bids. It is an ADVISORY finding surfaced like
-- every other alert (unread, read, dismissed), with a deterministic suggested primary a human resolves; it
-- never auto rejects a slate member. No new table: it rides the existing alerts table, sweep, audit, and
-- endpoints. Only the alert_type CHECK widens by one value.
ALTER TABLE alerts DROP CONSTRAINT IF EXISTS alerts_alert_type_check;
ALTER TABLE alerts ADD  CONSTRAINT alerts_alert_type_check
    CHECK (alert_type IN ('recompete_winnable', 'clearance_expiring', 'gap_fillable', 'collision'));

-- +goose Down
-- Clear the rows the narrower vocabulary cannot express BEFORE narrowing it. Without this the ADD fails
-- with a check violation and the whole rollback aborts: goose runs a migration in a transaction, so the
-- DROP above rolls back with it and nothing is corrupted, but the rollback is BLOCKED, which is the worst
-- moment to discover it since a rollback is usually being attempted under pressure.
--
-- Deleted rather than remapped: a collision alert has no meaning in a schema that does not know the type,
-- and the sweep that produced it regenerates from live data on its next run.
DELETE FROM alerts WHERE alert_type = 'collision';

ALTER TABLE alerts DROP CONSTRAINT IF EXISTS alerts_alert_type_check;
ALTER TABLE alerts ADD  CONSTRAINT alerts_alert_type_check
    CHECK (alert_type IN ('recompete_winnable', 'clearance_expiring', 'gap_fillable'));