CREATE TABLE IF NOT EXISTS user_sessions (
  id BIGINT AUTO_INCREMENT PRIMARY KEY,
  public_id CHAR(32) NOT NULL UNIQUE,
  user_id INT NOT NULL,
  ip VARCHAR(45) NULL,
  user_agent VARCHAR(512) NULL,
  created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  last_seen_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  expires_at DATETIME NOT NULL,
  revoked_at DATETIME NULL,
  revoked_by INT NULL,
  revoke_reason VARCHAR(32) NULL,
  INDEX idx_user_sessions_user (user_id, revoked_at, expires_at),
  CONSTRAINT fk_user_sessions_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
  CONSTRAINT fk_user_sessions_revoked_by FOREIGN KEY (revoked_by) REFERENCES users(id) ON DELETE SET NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;