-- 还原 subscriptions.source CHECK
CREATE TABLE subscriptions_old (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  user_id INTEGER NOT NULL,
  plan_id INTEGER NOT NULL,
  expires_at DATETIME NOT NULL,
  source TEXT NOT NULL CHECK (source IN ('trial','code','pay')),
  created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  FOREIGN KEY (user_id) REFERENCES users(id),
  FOREIGN KEY (plan_id) REFERENCES plans(id)
);
INSERT INTO subscriptions_old SELECT id,user_id,plan_id,expires_at,source,created_at
  FROM subscriptions WHERE source IN ('trial','code','pay');
DROP TABLE subscriptions;
ALTER TABLE subscriptions_old RENAME TO subscriptions;
CREATE INDEX idx_subs_user_exp ON subscriptions (user_id, expires_at);

DROP TABLE reward_claims;
DROP TABLE referrals;
DROP INDEX ux_users_invite_code;
ALTER TABLE users DROP COLUMN first_paid_at;
ALTER TABLE users DROP COLUMN invite_code;