-- ClientFlow v4 migration 004: stronger outbox idempotency and state visibility.
ALTER TABLE integration_outbox ADD COLUMN IF NOT EXISTS locked_at TIMESTAMPTZ;
ALTER TABLE integration_outbox ADD COLUMN IF NOT EXISTS lock_owner TEXT;
ALTER TABLE integration_outbox ADD COLUMN IF NOT EXISTS ignored_at TIMESTAMPTZ;

CREATE UNIQUE INDEX IF NOT EXISTS ux_integration_outbox_idempotency_key
ON integration_outbox(idempotency_key)
WHERE idempotency_key IS NOT NULL;

CREATE INDEX IF NOT EXISTS idx_integration_outbox_pending_dispatch
ON integration_outbox(target_system, created_at)
WHERE status = 'pending';