-- Trial / grant credits: a server-owned, idempotent balance grant that is not
-- a payment. Extends the existing kind constraint; safe to re-run.
DO $$
DECLARE cname text;
BEGIN
  SELECT conname INTO cname
    FROM pg_constraint
   WHERE conrelid = 'opt_credit_events'::regclass
     AND contype = 'c'
     AND pg_get_constraintdef(oid) LIKE '%kind%';
  IF cname IS NOT NULL THEN
    EXECUTE format('ALTER TABLE opt_credit_events DROP CONSTRAINT %I', cname);
  END IF;
  ALTER TABLE opt_credit_events ADD CONSTRAINT opt_credit_events_kind_check
    CHECK (kind IN ('verified_payment', 'grant', 'reserve', 'settle', 'release'));
END $$;