CREATE TABLE IF NOT EXISTS `task_progress_snapshot` (
  `id` BIGINT NOT NULL AUTO_INCREMENT,
  `snapshot_time` DATETIME NOT NULL,
  `metrics_json` TEXT,
  `status_distribution_json` TEXT,
  `trend_json` TEXT,
  `stage_segments_json` TEXT,
  `department_load_json` MEDIUMTEXT,
  `risk_tasks_json` MEDIUMTEXT,
  `task_points_json` MEDIUMTEXT,
  `created_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  KEY `idx_snapshot_time` (`snapshot_time`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;