CREATE TABLE IF NOT EXISTS push_subscriptions (
  id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
  user_id INT UNSIGNED NOT NULL,
  endpoint TEXT NOT NULL,
  p256dh VARCHAR(255) NOT NULL,
  auth VARCHAR(255) NOT NULL,
  reminder_days INT UNSIGNED NOT NULL DEFAULT 3,
  last_sent_at DATETIME DEFAULT NULL,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
  UNIQUE KEY unique_user_sub (user_id, endpoint(255))
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;