diff --git a/src/main/resources/sql/homework_add_sch_id.sql b/src/main/resources/sql/homework_add_sch_id.sql
new file mode 100644
index 0000000..2842a06
--- /dev/null
+++ b/src/main/resources/sql/homework_add_sch_id.sql
@@ -0,0 +1,16 @@
+-- ============================================================
+-- homework 表补 sch_id 列（多租户隔离）
+-- 决策 D3：发布时从 BoaUser.currentRole.schId 填充，查询时按校过滤
+--
+-- 对应实体：Homework.schId / HomeworkRepository 多租户统计方法
+--
+-- 执行方式：由 DBA 手动在对应环境执行，AI 不代跑
+-- MySQL 5.7+ 兼容
+-- ============================================================
+
+-- 1) 加列
+ALTER TABLE `homework`
+    ADD COLUMN `sch_id` INT NULL COMMENT '学校ID（多租户隔离：发布时从当前用户角色填充）';
+
+-- 2) 加索引（用于按学校过滤查询）
+CREATE INDEX `idx_homework_sch_id` ON `homework` (`sch_id`);
diff --git a/src/main/resources/sql/homework_data_backfill.sql b/src/main/resources/sql/homework_data_backfill.sql
new file mode 100644
index 0000000..89d6433
--- /dev/null
+++ b/src/main/resources/sql/homework_data_backfill.sql
@@ -0,0 +1,162 @@
+-- ============================================================
+-- 存量数据回填脚本
+-- 1. homework.sch_id：按发布人所属学校回填（从用户中心/平台用户表按发布人ID取 sch_id）
+-- 2. homework_receiver：从 homework.receive_list JSON 字符串展开为关联表行
+--
+-- 人员标识口径：教师/学生一律为用户中心数字ID（publisher_id / receiver_id），
+--               不再使用登录账号（*account 列已由 v3_account_to_id_refactor.sql 删除）。
+--               receive_list 中的历史登录名（非数字）条目直接跳过，不落库。
+--
+-- 幂等设计：可重复执行，已存在的数据不会重复插入
+-- 执行方式：由 DBA 手动在对应环境执行，AI 不代跑
+-- 执行顺序：务必在 v3_account_to_id_refactor.sql 之后执行（依赖 publisher_id / receiver_id 列）
+-- MySQL 5.7+ 兼容
+-- ============================================================
+
+-- ============================================================
+-- Part 1：回填 homework.sch_id
+-- ============================================================
+
+-- 方式一：如果平台用户表有 sch_id 字段，按发布人ID（publisher_id）关联回填
+-- 注意：base_user 为平台库表示例，id/sch_id 列名需按实际平台库结构调整
+UPDATE `homework` n
+    INNER JOIN (
+        SELECT DISTINCT u.id, u.sch_id
+        FROM base_user u
+        WHERE u.sch_id IS NOT NULL
+    ) t ON n.publisher_id = t.id
+SET n.sch_id = t.sch_id
+WHERE n.sch_id IS NULL
+  AND n.publisher_id IS NOT NULL;
+
+-- 方式二（备用）：如果用户学校关系在 sys_user_role_rel 表
+-- 取每个用户的主身份学校（is_main=1），按用户ID回填
+-- 取消注释后执行（视实际库表结构选用，r 表用户ID列名需按实际结构调整）
+--
+-- UPDATE `homework` n
+--     INNER JOIN (
+--         SELECT r.user_id, r.sch_id
+--         FROM sys_user_role_rel r
+--         WHERE r.is_main = 1
+--           AND r.sch_id IS NOT NULL
+--     ) t ON n.publisher_id = t.user_id
+-- SET n.sch_id = t.sch_id
+-- WHERE n.sch_id IS NULL
+--   AND n.publisher_id IS NOT NULL;
+
+
+-- ============================================================
+-- Part 2：从 homework.receive_list 展开到 homework_receiver 关联表
+-- ============================================================
+
+-- 说明：
+-- - homework.receive_list 存储格式有两种：
+--   1) "ALL"（全员作业）—— 不写明细行，跳过
+--   2) JSON 数组 ["10012","10013",...]（用户中心数字ID）或逗号分隔串
+-- - 仅数字条目落库（receiver_id 为 INT 非空）；历史登录名条目跳过
+-- - 本脚本使用 MySQL 函数解析（MySQL 5.7+ 支持）
+-- - 对于非标准 JSON 格式（逗号分隔串），使用循环逐条插入
+-- - 幂等：每次插入前先删除该作业的旧接收人记录
+
+-- 注意：MySQL 5.7 的 JSON_TABLE 不可用，这里用存储过程逐条解析
+
+DELIMITER $$
+
+-- 存储过程：展开单个作业的接收人列表
+DROP PROCEDURE IF EXISTS `expand_homework_receivers`$$
+CREATE PROCEDURE `expand_homework_receivers`()
+BEGIN
+    DECLARE v_done INT DEFAULT 0;
+    DECLARE v_homework_id INT;
+    DECLARE v_receive_list TEXT;
+    DECLARE cur CURSOR FOR
+        SELECT id, receive_list
+        FROM homework
+        WHERE receive_list IS NOT NULL
+          AND TRIM(receive_list) != ''
+          AND UPPER(TRIM(receive_list)) != 'ALL'
+          AND NOT EXISTS (
+              SELECT 1 FROM homework_receiver WHERE homework_id = homework.id LIMIT 1
+          );
+    DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_done = 1;
+
+    OPEN cur;
+    read_loop: LOOP
+        FETCH cur INTO v_homework_id, v_receive_list;
+        IF v_done = 1 THEN
+            LEAVE read_loop;
+        END IF;
+
+        -- 清理旧数据（幂等）
+        DELETE FROM homework_receiver WHERE homework_id = v_homework_id;
+
+        SET v_receive_list = TRIM(v_receive_list);
+
+        -- 去除首尾方括号（如有）
+        IF LEFT(v_receive_list, 1) = '[' AND RIGHT(v_receive_list, 1) = ']' THEN
+            SET v_receive_list = SUBSTRING(v_receive_list, 2, CHAR_LENGTH(v_receive_list) - 2);
+        END IF;
+
+        -- 替换引号为空，按逗号分隔
+        SET v_receive_list = REPLACE(REPLACE(v_receive_list, '"', ''), '''', '');
+
+        -- 逐条插入
+        BEGIN
+            DECLARE v_entry VARCHAR(64);
+            DECLARE v_remaining TEXT;
+            SET v_remaining = v_receive_list;
+
+            WHILE v_remaining IS NOT NULL AND TRIM(v_remaining) != '' DO
+                IF LOCATE(',', v_remaining) > 0 THEN
+                    SET v_entry = TRIM(SUBSTRING_INDEX(v_remaining, ',', 1));
+                    SET v_remaining = SUBSTRING(v_remaining, LOCATE(',', v_remaining) + 1);
+                ELSE
+                    SET v_entry = TRIM(v_remaining);
+                    SET v_remaining = NULL;
+                END IF;
+
+                -- 仅落数字条目（用户中心数字ID）；历史登录名跳过
+                IF v_entry != '' AND v_entry IS NOT NULL
+                   AND v_entry REGEXP '^[0-9]+$' THEN
+                    INSERT INTO homework_receiver
+                        (homework_id, receiver_id, receive_type, create_time)
+                    VALUES
+                        (v_homework_id, CAST(v_entry AS UNSIGNED), 1, NOW());
+                END IF;
+            END WHILE;
+        END;
+    END LOOP;
+
+    CLOSE cur;
+END$$
+
+DELIMITER ;
+
+-- 执行存储过程
+CALL expand_homework_receivers();
+
+-- 清理临时存储过程
+DROP PROCEDURE IF EXISTS `expand_homework_receivers`;
+
+-- ============================================================
+-- 回填结果验证查询（执行后手动检查）
+-- ============================================================
+
+-- 检查1：sch_id 回填覆盖率
+-- SELECT
+--     COUNT(*) AS total,
+--     SUM(CASE WHEN sch_id IS NOT NULL THEN 1 ELSE 0 END) AS sch_id_filled,
+--     SUM(CASE WHEN sch_id IS NULL THEN 1 ELSE 0 END) AS sch_id_null
+-- FROM homework;
+
+-- 检查2：homework_receiver 展开行数
+-- SELECT COUNT(*) FROM homework_receiver;
+
+-- 检查3：未展开的作业（receive_list 非空非 ALL 但 receiver 表无记录）
+-- SELECT n.id, n.receive_list
+-- FROM homework n
+-- LEFT JOIN homework_receiver r ON r.homework_id = n.id
+-- WHERE n.receive_list IS NOT NULL
+--   AND TRIM(n.receive_list) != ''
+--   AND UPPER(TRIM(n.receive_list)) != 'ALL'
+--   AND r.id IS NULL;
diff --git a/src/main/resources/sql/homework_receiver_create.sql b/src/main/resources/sql/homework_receiver_create.sql
new file mode 100644
index 0000000..b414f22
--- /dev/null
+++ b/src/main/resources/sql/homework_receiver_create.sql
@@ -0,0 +1,26 @@
+-- ============================================================
+-- homework_receiver 建表（替代 homework.receive_list JSON 字符串存储）
+-- 决策 D2-B：拆关联表，支撑阅读情况/催收/统计 SQL 化
+--
+-- 对应实体：com.yunhai.homework.entity.HomeworkReceiver
+-- 人员口径：接收人存「用户ID + 姓名快照」（receiver_id + receiver_name），不含登录账号
+-- 索引：idx_homework_id(homework_id) + idx_receiver(receiver_id)
+--
+-- 执行方式：由 DBA 手动在对应环境执行，AI 不代跑
+-- MySQL 5.7+ 兼容
+-- ============================================================
+
+CREATE TABLE IF NOT EXISTS `homework_receiver` (
+    `id`             INT          NOT NULL AUTO_INCREMENT COMMENT '自增主键',
+    `homework_id`    INT          NOT NULL                COMMENT '作业ID（关联 homework.id）',
+    `receiver_id`    INT          NOT NULL                COMMENT '接收人ID（用户中心数字ID）',
+    `receiver_name`  VARCHAR(64)  NULL                    COMMENT '接收人姓名快照',
+    `receive_type`   INT          NOT NULL DEFAULT 1      COMMENT '接收类型：1 接收 / 2 抄送',
+    `create_by`      VARCHAR(64)  NULL                    COMMENT '创建人ID（审计填充）',
+    `create_time`    DATETIME     NULL                    COMMENT '创建时间（审计填充）',
+    `update_by`      VARCHAR(64)  NULL                    COMMENT '更新人ID（审计填充）',
+    `update_time`    DATETIME     NULL                    COMMENT '更新时间（审计填充）',
+    PRIMARY KEY (`id`),
+    KEY `idx_homework_id` (`homework_id`),
+    KEY `idx_receiver` (`receiver_id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='作业接收人关联表';
diff --git a/src/main/resources/sql/v3_account_to_id_refactor.sql b/src/main/resources/sql/v3_account_to_id_refactor.sql
new file mode 100644
index 0000000..c5e67f9
--- /dev/null
+++ b/src/main/resources/sql/v3_account_to_id_refactor.sql
@@ -0,0 +1,92 @@
+-- ============================================================
+-- 去账号化改造迁移脚本：人员标识统一为「用户ID + 姓名快照」
+--
+-- 背景：业务表中教师/学生身份原以登录账号（account）承载，现统一改为
+--       平台用户ID + 姓名快照，登录身份口径变为 LoginUser.userId：
+--         homework.publisher_account      → publisher_id（+ publisher_name 既有）
+--         homework_read.reader_account    → reader_id（+ reader_name 既有）
+--         homework_receiver.account       → receiver_id + receiver_name
+--         class_student.user_account      → 删除（student_id 即平台用户ID）
+--         notification.receiver_account   → receiver_id + receiver_name
+--         homework_submission.reviewed_by → 语义改为批阅人ID，新增 reviewed_by_name
+--         contacts_group.creator_account  → creator_id
+--         contacts_group_user.user_account→ 删除（保留 user_id + user_name）
+--       审计列 create_by / update_by 语义同步改为「用户ID」，存量登录名不强改。
+--
+-- 回填口径：存量的 *account 列原样拷贝到对应 *_id 列（历史值可能是登录名，
+--           也可能是历史数字ID），不做远程换算；读取侧已有「按登录名查不到
+--           再按数字ID查」的兜底。如需精确换算可另行按用户中心批量清洗。
+--
+-- 执行方式：由 DBA 手动在对应环境执行，AI 不代跑
+-- 执行顺序：务必先执行本脚本，再部署新版应用（新版仅新增列，不会删除旧账号列；
+--           先部署会导致 uk_homework_reader 同名唯一键冲突、旧列残留）
+-- MySQL 5.7+ 兼容（不支持 ADD COLUMN IF NOT EXISTS，重复执行前先核对列/索引）
+-- ============================================================
+
+-- ---------------------------------------------------------------------
+-- 1. homework：发布人 账号 → ID
+-- ---------------------------------------------------------------------
+ALTER TABLE `homework`
+    ADD COLUMN `publisher_id` VARCHAR(64) NULL COMMENT '发布人ID（平台用户ID）' AFTER `publisher_account`;
+UPDATE `homework` SET `publisher_id` = `publisher_account` WHERE `publisher_id` IS NULL;
+ALTER TABLE `homework` DROP COLUMN `publisher_account`;
+
+-- ---------------------------------------------------------------------
+-- 2. homework_read：读者 账号 → ID（唯一键同步重建）
+-- ---------------------------------------------------------------------
+ALTER TABLE `homework_read`
+    ADD COLUMN `reader_id` VARCHAR(64) NULL COMMENT '读者ID（平台用户ID）' AFTER `homework_id`;
+UPDATE `homework_read` SET `reader_id` = `reader_account` WHERE `reader_id` IS NULL;
+ALTER TABLE `homework_read` MODIFY `reader_id` VARCHAR(64) NOT NULL COMMENT '读者ID（平台用户ID）';
+ALTER TABLE `homework_read` DROP INDEX `uk_homework_reader`;
+ALTER TABLE `homework_read` DROP COLUMN `reader_account`;
+ALTER TABLE `homework_read` ADD UNIQUE KEY `uk_homework_reader` (`homework_id`, `reader_id`);
+
+-- ---------------------------------------------------------------------
+-- 3. homework_receiver：接收人 账号 → ID + 姓名快照
+--    （表由 homework_receiver_create.sql 单独建，低环境不存在时跳过本节）
+-- ---------------------------------------------------------------------
+ALTER TABLE `homework_receiver`
+    ADD COLUMN `receiver_id`   VARCHAR(64) NULL COMMENT '接收人ID（平台用户ID）' AFTER `homework_id`,
+    ADD COLUMN `receiver_name` VARCHAR(64) NULL COMMENT '接收人姓名快照' AFTER `receiver_id`;
+UPDATE `homework_receiver` SET `receiver_id` = `account` WHERE `receiver_id` IS NULL;
+ALTER TABLE `homework_receiver` MODIFY `receiver_id` VARCHAR(64) NOT NULL COMMENT '接收人ID（平台用户ID）';
+ALTER TABLE `homework_receiver` DROP INDEX `idx_account`;
+ALTER TABLE `homework_receiver` DROP COLUMN `account`;
+ALTER TABLE `homework_receiver` ADD INDEX `idx_receiver` (`receiver_id`);
+
+-- ---------------------------------------------------------------------
+-- 4. class_student：删除登录账号列（身份口径 = student_id 即平台用户ID）
+-- ---------------------------------------------------------------------
+ALTER TABLE `class_student` DROP INDEX `idx_account`;
+ALTER TABLE `class_student` DROP COLUMN `user_account`;
+
+-- ---------------------------------------------------------------------
+-- 5. notification：接收人 账号 → ID + 姓名快照
+-- ---------------------------------------------------------------------
+ALTER TABLE `notification`
+    ADD COLUMN `receiver_id`   VARCHAR(64) NULL COMMENT '接收人ID（学生=student_id，教师=平台用户ID）' AFTER `content`,
+    ADD COLUMN `receiver_name` VARCHAR(64) NULL COMMENT '接收人姓名快照' AFTER `receiver_id`;
+UPDATE `notification` SET `receiver_id` = `receiver_account` WHERE `receiver_id` IS NULL;
+ALTER TABLE `notification` MODIFY `receiver_id` VARCHAR(64) NOT NULL COMMENT '接收人ID（学生=student_id，教师=平台用户ID）';
+ALTER TABLE `notification` DROP INDEX `idx_receiver`;
+ALTER TABLE `notification` DROP COLUMN `receiver_account`;
+ALTER TABLE `notification` ADD INDEX `idx_receiver` (`receiver_id`, `is_read`);
+
+-- ---------------------------------------------------------------------
+-- 6. homework_submission：reviewed_by 语义改为批阅人ID，补姓名快照列
+-- ---------------------------------------------------------------------
+ALTER TABLE `homework_submission`
+    ADD COLUMN `reviewed_by_name` VARCHAR(64) NULL COMMENT '批阅人姓名快照' AFTER `reviewed_by`;
+ALTER TABLE `homework_submission`
+    MODIFY `reviewed_by` VARCHAR(64) NULL COMMENT '批阅人ID（平台用户ID）';
+
+-- ---------------------------------------------------------------------
+-- 7. contacts_group / contacts_group_user：联系组去账号
+-- ---------------------------------------------------------------------
+ALTER TABLE `contacts_group`
+    ADD COLUMN `creator_id` VARCHAR(64) NULL COMMENT '创建人ID（平台用户ID）' AFTER `group_name`;
+UPDATE `contacts_group` SET `creator_id` = `creator_account` WHERE `creator_id` IS NULL;
+ALTER TABLE `contacts_group` DROP COLUMN `creator_account`;
+
+ALTER TABLE `contacts_group_user` DROP COLUMN `user_account`;
diff --git a/src/main/resources/sql/v3_schema.sql b/src/main/resources/sql/v3_schema.sql
new file mode 100644
index 0000000..571f162
--- /dev/null
+++ b/src/main/resources/sql/v3_schema.sql
@@ -0,0 +1,182 @@
+-- =====================================================================
+-- 课堂作业 V3（PRD V1.0）全量 DDL —— classwork-homework-plan-v3.md §5
+-- 库：classhomework（MySQL 5.7+）
+-- 说明：
+--   1) 开发环境 ddl-auto=update 会自动建表/加列，本脚本用于生产与手工初始化；
+--   2) MySQL 5.7 不支持 ADD COLUMN IF NOT EXISTS，重复执行前请先核对列是否存在；
+--   3) 定时发布时间复用 homework.timing_send_time（PRD scheduled_at 同义），不新增列。
+--   4) 人员标识口径：教师/学生一律为用户中心数字ID（INT），不存登录账号
+--      （与 v3_account_to_id_refactor.sql / v4_person_id_to_int.sql 收敛后的最终形态一致）。
+-- =====================================================================
+
+-- ---------------------------------------------------------------------
+-- 1. homework 扩展列（§5.1）
+-- ---------------------------------------------------------------------
+ALTER TABLE `homework`
+    ADD COLUMN `subject`      VARCHAR(50)  NULL COMMENT '学科（字典值）',
+    ADD COLUMN `deadline_at`  DATETIME     NULL COMMENT '截止时间（精确到分钟；空=仅查阅型）',
+    ADD COLUMN `hw_status`    VARCHAR(20)  NOT NULL DEFAULT 'DRAFT_UNPUBLISHED'
+                                           COMMENT 'DRAFT_UNPUBLISHED/DRAFT_SCHEDULED/PUBLISHED/CLOSED/ARCHIVED',
+    ADD COLUMN `published_at` DATETIME     NULL COMMENT '发布时间（立即/定时到点均写）',
+    ADD COLUMN `submit_type`  VARCHAR(100) NULL COMMENT 'JSON 数组 ["image","attach","text","none"]',
+    ADD COLUMN `allow_late`   TINYINT      NOT NULL DEFAULT 0 COMMENT '截止后是否允许逾期提交',
+    ADD COLUMN `remind_1d`    TINYINT      NOT NULL DEFAULT 1 COMMENT '截止前 1 天提醒',
+    ADD COLUMN `remind_1h`    TINYINT      NOT NULL DEFAULT 1 COMMENT '截止前 1 小时提醒',
+    ADD COLUMN `archived_at`  DATETIME     NULL COMMENT '归档时间';
+
+-- ---------------------------------------------------------------------
+-- 2. homework_class 作业-班级关联（§5.2）
+-- ---------------------------------------------------------------------
+CREATE TABLE IF NOT EXISTS `homework_class` (
+    `id`          INT NOT NULL AUTO_INCREMENT,
+    `homework_id` INT NOT NULL,
+    `class_id`    VARCHAR(64) NOT NULL,
+    `class_name`  VARCHAR(50) NULL COMMENT '班级名快照',
+    `create_by`   VARCHAR(64) NULL,
+    `create_time` DATETIME NULL,
+    `update_by`   VARCHAR(64) NULL,
+    `update_time` DATETIME NULL,
+    PRIMARY KEY (`id`),
+    UNIQUE KEY `uk_hw_class` (`homework_id`, `class_id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='作业班级关联';
+
+-- ---------------------------------------------------------------------
+-- 3. homework_attachment 作业附件（§5.3）
+-- ---------------------------------------------------------------------
+CREATE TABLE IF NOT EXISTS `homework_attachment` (
+    `id`          INT NOT NULL AUTO_INCREMENT,
+    `homework_id` INT NOT NULL,
+    `file_id`     INT NULL COMMENT 'up_file.id',
+    `file_url`    VARCHAR(500) NOT NULL,
+    `file_type`   VARCHAR(20)  NULL COMMENT 'image/file/...',
+    `file_name`   VARCHAR(200) NULL,
+    `sort`        INT NOT NULL DEFAULT 0,
+    `create_by`   VARCHAR(64) NULL,
+    `create_time` DATETIME NULL,
+    `update_by`   VARCHAR(64) NULL,
+    `update_time` DATETIME NULL,
+    KEY `idx_hw` (`homework_id`),
+    PRIMARY KEY (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='作业附件';
+
+-- ---------------------------------------------------------------------
+-- 4. homework_read_record 学生阅读记录（§5.4）
+-- ---------------------------------------------------------------------
+CREATE TABLE IF NOT EXISTS `homework_read_record` (
+    `id`            INT NOT NULL AUTO_INCREMENT,
+    `homework_id`   INT NOT NULL,
+    `student_id`    INT NOT NULL COMMENT '学生ID（用户中心数字ID，即 SchStudent.UserStuSerID）',
+    `student_name`  VARCHAR(50) NULL,
+    `class_id`      VARCHAR(64) NULL,
+    `is_read`       TINYINT NOT NULL DEFAULT 0 COMMENT '0 UNREAD / 1 READ',
+    `first_read_at` DATETIME NULL,
+    `last_read_at`  DATETIME NULL,
+    `read_count`    INT NOT NULL DEFAULT 0,
+    `create_by`     VARCHAR(64) NULL,
+    `create_time`   DATETIME NULL,
+    `update_by`     VARCHAR(64) NULL,
+    `update_time`   DATETIME NULL,
+    PRIMARY KEY (`id`),
+    UNIQUE KEY `uk_hw_student` (`homework_id`, `student_id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='学生作业阅读记录';
+
+-- ---------------------------------------------------------------------
+-- 5. homework_submission 提交（多版本，§5.5）
+-- ---------------------------------------------------------------------
+CREATE TABLE IF NOT EXISTS `homework_submission` (
+    `id`            INT NOT NULL AUTO_INCREMENT,
+    `homework_id`   INT NOT NULL,
+    `student_id`    INT NOT NULL COMMENT '学生ID（用户中心数字ID，即 SchStudent.UserStuSerID）',
+    `student_name`  VARCHAR(50) NOT NULL,
+    `class_id`      VARCHAR(64) NOT NULL,
+    `class_name`    VARCHAR(50) NOT NULL,
+    `version`       INT NOT NULL DEFAULT 1 COMMENT '提交版本，同一学生单调递增',
+    `is_latest`     TINYINT NOT NULL DEFAULT 1 COMMENT '1 当前版本 / 0 历史',
+    `status`        VARCHAR(20) NOT NULL DEFAULT 'SUBMITTED'
+                    COMMENT 'NOT_SUBMITTED/SUBMITTED/LATE_SUBMITTED/RETURNED/REVIEWED',
+    `is_late`       TINYINT NOT NULL DEFAULT 0,
+    `submitted_at`  DATETIME NULL,
+    `text`          TEXT NULL,
+    `score`         DECIMAL(6,2) NULL,
+    `comment`       TEXT NULL COMMENT '评语（打回时=订正原因）',
+    `review_status` VARCHAR(20) NOT NULL DEFAULT 'PENDING' COMMENT 'PENDING/REVIEWED/RETURNED',
+    `reviewed_by`   INT NULL COMMENT '批阅人ID（用户中心数字ID，同教师ID空间）',
+    `reviewed_by_name` VARCHAR(64) NULL COMMENT '批阅人姓名快照',
+    `reviewed_at`   DATETIME NULL,
+    `create_by`     VARCHAR(64) NULL,
+    `create_time`   DATETIME NULL,
+    `update_by`     VARCHAR(64) NULL,
+    `update_time`   DATETIME NULL,
+    PRIMARY KEY (`id`),
+    UNIQUE KEY `uk_hw_student_ver` (`homework_id`, `student_id`, `version`),
+    KEY `idx_latest` (`homework_id`, `student_id`, `is_latest`),
+    KEY `idx_status` (`homework_id`, `status`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='作业提交（多版本）';
+
+-- ---------------------------------------------------------------------
+-- 6. submission_attachment 提交附件（§5.6）
+-- ---------------------------------------------------------------------
+CREATE TABLE IF NOT EXISTS `submission_attachment` (
+    `id`            INT NOT NULL AUTO_INCREMENT,
+    `submission_id` INT NOT NULL,
+    `homework_id`   INT NOT NULL COMMENT '冗余，便于统计与清理',
+    `student_id`    INT NULL COMMENT '学生ID（用户中心数字ID）',
+    `file_id`       INT NULL COMMENT 'up_file.id',
+    `file_url`      VARCHAR(500) NOT NULL,
+    `file_type`     VARCHAR(20)  NULL COMMENT 'image/file',
+    `file_name`     VARCHAR(200) NULL,
+    `sort`          INT NOT NULL DEFAULT 0,
+    `create_by`     VARCHAR(64) NULL,
+    `create_time`   DATETIME NULL,
+    `update_by`     VARCHAR(64) NULL,
+    `update_time`   DATETIME NULL,
+    KEY `idx_sub` (`submission_id`),
+    PRIMARY KEY (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='提交附件';
+
+-- ---------------------------------------------------------------------
+-- 7. class_student 班级学生名册快照（§5.7，沿用 V2.1 §7.3）
+-- ---------------------------------------------------------------------
+CREATE TABLE IF NOT EXISTS `class_student` (
+    `id`           INT NOT NULL AUTO_INCREMENT,
+    `school_id`    INT NOT NULL,
+    `class_id`     VARCHAR(64) NOT NULL,
+    `class_name`   VARCHAR(50) NULL,
+    `grade_name`   VARCHAR(50) NULL,
+    `student_id`   INT NOT NULL COMMENT '学生ID（用户中心数字ID，即 SchStudent.UserStuSerID）',
+    `student_name` VARCHAR(50) NOT NULL,
+    `status`       TINYINT NOT NULL DEFAULT 1 COMMENT '1 在班 0 已转出/退课',
+    `leave_at`     DATETIME NULL,
+    `create_by`    VARCHAR(64) NULL,
+    `create_time`  DATETIME NULL,
+    `update_by`    VARCHAR(64) NULL,
+    `update_time`  DATETIME NULL,
+    PRIMARY KEY (`id`),
+    UNIQUE KEY `uk_class_student` (`class_id`, `student_id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='班级学生名册快照';
+
+-- ---------------------------------------------------------------------
+-- 8. notification 站内通知（§5.8）
+-- ---------------------------------------------------------------------
+CREATE TABLE IF NOT EXISTS `notification` (
+    `id`               INT NOT NULL AUTO_INCREMENT,
+    `type`             VARCHAR(30) NOT NULL
+                       COMMENT 'HOMEWORK_PUBLISHED/DEADLINE_REMINDER/NOT_SUBMITTED/NOT_READ/REVIEW_DONE/RETURNED/SCHEDULE_FAILED/DEADLINE_CHANGED',
+    `homework_id`      INT NULL,
+    `related_id`       INT NULL COMMENT '关联业务 id（submissionId；截止提醒存档位 1=1天档 2=1小时档）',
+    `title`            VARCHAR(200) NOT NULL,
+    `content`          VARCHAR(1000) NULL,
+    `receiver_id`      INT NOT NULL COMMENT '接收人ID（用户中心数字ID：学生=student_id，教师=同域数字ID）',
+    `receiver_name`    VARCHAR(64) NULL COMMENT '接收人姓名快照',
+    `receiver_role`    VARCHAR(20) NOT NULL DEFAULT 'student' COMMENT 'student/teacher',
+    `is_read`          TINYINT NOT NULL DEFAULT 0,
+    `read_at`          DATETIME NULL,
+    `send_channel`     VARCHAR(20) NOT NULL DEFAULT 'inapp' COMMENT 'inapp/sms',
+    `create_by`        VARCHAR(64) NULL,
+    `create_time`      DATETIME NULL,
+    `update_by`        VARCHAR(64) NULL,
+    `update_time`      DATETIME NULL,
+    KEY `idx_receiver` (`receiver_id`, `is_read`),
+    KEY `idx_hw_type` (`homework_id`, `type`),
+    PRIMARY KEY (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='站内通知';
diff --git a/src/main/resources/sql/v3_seed.sql b/src/main/resources/sql/v3_seed.sql
new file mode 100644
index 0000000..96c8cbc
--- /dev/null
+++ b/src/main/resources/sql/v3_seed.sql
@@ -0,0 +1,33 @@
+-- =====================================================================
+-- 课堂作业 V3 本地联调种子数据
+-- 用途：bschclass 名册/任教开放接口未就绪期间（计划 §13-1），填充
+--      class_student（名册/班级树）与 sch_class_teach（任教关系/任教学科）
+--      供学生端身份映射（用户中心数字ID ↔ student_id）、教师学科下拉联调。
+-- 注意：仅限本地/联调环境执行；school_id=3（云海中学）、tea_id=10008（李晶）
+--      请按实际登录账号的学校/教师 id 调整；
+--      student_id / tea_id 为用户中心数字ID（INT），非登录账号。
+--      sub_id 本地无学科字典时编码即展示名（如 '数学'）。
+-- =====================================================================
+
+-- 初一(1)班 C1：3 名学生
+INSERT INTO `class_student`
+    (`school_id`, `class_id`, `class_name`, `grade_name`, `student_id`, `student_name`, `status`, `create_time`, `update_time`)
+VALUES
+    (3, 'C1', '初一(1)班', '初一', 10001, '张一',   1, NOW(), NOW()),
+    (3, 'C1', '初一(1)班', '初一', 10002, '王二',   1, NOW(), NOW()),
+    (3, 'C1', '初一(1)班', '初一', 10003, '李三',   1, NOW(), NOW());
+
+-- 初一(2)班 C2：3 名学生
+INSERT INTO `class_student`
+    (`school_id`, `class_id`, `class_name`, `grade_name`, `student_id`, `student_name`, `status`, `create_time`, `update_time`)
+VALUES
+    (3, 'C2', '初一(2)班', '初一', 10004, '赵四',   1, NOW(), NOW()),
+    (3, 'C2', '初一(2)班', '初一', 10005, '钱五',   1, NOW(), NOW()),
+    (3, 'C2', '初一(2)班', '初一', 10006, '孙六',   1, NOW(), NOW());
+
+-- 任教关系：李晶(10008) 任教 C1/C2 数学（bschclass 不可用时的任教学科降级数据源）
+INSERT INTO `sch_class_teach`
+    (`school_id`, `class_id`, `tea_id`, `sub_id`, `status`, `create_time`, `update_time`)
+VALUES
+    (3, 'C1', 10008, '数学', 1, NOW(), NOW()),
+    (3, 'C2', 10008, '数学', 1, NOW(), NOW());
diff --git a/src/main/resources/sql/v4_person_id_to_int.sql b/src/main/resources/sql/v4_person_id_to_int.sql
new file mode 100644
index 0000000..60e2349
--- /dev/null
+++ b/src/main/resources/sql/v4_person_id_to_int.sql
@@ -0,0 +1,106 @@
+-- ============================================================
+-- 人员标识数字化迁移脚本：教师/学生 ID 列 VARCHAR(64) → INT
+--
+-- 背景：人员身份统一为用户中心数字ID（BoaUser.id，与 bschclass 的
+--       SchTeacher.UserTeaSerID / SchStudent.UserStuSerID 同一 ID 空间），
+--       应用侧实体字段已同步改为 Integer，当前登录人经
+--       utils/UserContext.getUserId() 解析（LoginUser.userId 非数字时
+--       回退用户中心按登录名反查）。
+--
+-- 覆盖列（人员标识，不含 create_by/update_by 审计列）：
+--   homework.publisher_id            发布人（教师）
+--   homework_read.reader_id          读者（教师）
+--   homework_receiver.receiver_id    接收人（教师/学生）
+--   homework_submission.student_id   学生
+--   homework_submission.reviewed_by  批阅人（教师）
+--   homework_read_record.student_id  学生
+--   submission_attachment.student_id 学生
+--   class_student.student_id         学生
+--   notification.receiver_id         接收人（教师/学生）
+--   contacts_group.creator_id        联系组创建人（教师）
+--
+-- 存量清洗口径：v3_account_to_id_refactor 回填时可能带入历史登录名（非数字）。
+--   可空列：非数字置 NULL（*_name 姓名快照保留，展示侧兜底）；
+--   非空列：非数字行物理删除（如需保留请 DBA 先按用户中心人工换算后再执行）。
+--   homework.receive_list JSON 内的历史登录名条目由应用读取侧忽略（仅取数字条目）。
+--
+-- 执行方式：由 DBA 手动在对应环境执行，AI 不代跑
+-- 执行顺序：务必先执行本脚本，再部署新版应用
+-- MySQL 5.7+ 兼容；低环境不存在 homework_receiver 表时跳过对应小节；
+-- 重复执行前先核对列类型
+-- ============================================================
+
+-- ---------------------------------------------------------------------
+-- 1. homework：发布人ID → INT（可空）
+-- ---------------------------------------------------------------------
+UPDATE `homework`
+    SET `publisher_id` = NULL
+    WHERE `publisher_id` IS NOT NULL AND `publisher_id` NOT REGEXP '^[0-9]+$';
+ALTER TABLE `homework`
+    MODIFY `publisher_id` INT NULL COMMENT '发布人ID（用户中心数字ID，同教师ID空间）';
+
+-- ---------------------------------------------------------------------
+-- 2. homework_read：读者ID → INT（NOT NULL，uk_homework_reader 不变）
+-- ---------------------------------------------------------------------
+DELETE FROM `homework_read` WHERE `reader_id` NOT REGEXP '^[0-9]+$';
+ALTER TABLE `homework_read`
+    MODIFY `reader_id` INT NOT NULL COMMENT '读者ID（用户中心数字ID，同教师ID空间）';
+
+-- ---------------------------------------------------------------------
+-- 3. homework_receiver：接收人ID → INT（NOT NULL）
+--    （表由 homework_receiver_create.sql 单独建，低环境不存在时跳过本节）
+-- ---------------------------------------------------------------------
+DELETE FROM `homework_receiver` WHERE `receiver_id` NOT REGEXP '^[0-9]+$';
+ALTER TABLE `homework_receiver`
+    MODIFY `receiver_id` INT NOT NULL COMMENT '接收人ID（用户中心数字ID）';
+
+-- ---------------------------------------------------------------------
+-- 4. homework_submission：学生ID → INT（NOT NULL，uk/idx 不变）+ 批阅人ID → INT（可空）
+-- ---------------------------------------------------------------------
+DELETE FROM `homework_submission` WHERE `student_id` NOT REGEXP '^[0-9]+$';
+ALTER TABLE `homework_submission`
+    MODIFY `student_id` INT NOT NULL COMMENT '学生ID（用户中心数字ID，即 SchStudent.UserStuSerID）';
+UPDATE `homework_submission`
+    SET `reviewed_by` = NULL
+    WHERE `reviewed_by` IS NOT NULL AND `reviewed_by` NOT REGEXP '^[0-9]+$';
+ALTER TABLE `homework_submission`
+    MODIFY `reviewed_by` INT NULL COMMENT '批阅人ID（用户中心数字ID，同教师ID空间）';
+
+-- ---------------------------------------------------------------------
+-- 5. homework_read_record：学生ID → INT（NOT NULL，uk_hw_student 不变）
+-- ---------------------------------------------------------------------
+DELETE FROM `homework_read_record` WHERE `student_id` NOT REGEXP '^[0-9]+$';
+ALTER TABLE `homework_read_record`
+    MODIFY `student_id` INT NOT NULL COMMENT '学生ID（用户中心数字ID，即 SchStudent.UserStuSerID）';
+
+-- ---------------------------------------------------------------------
+-- 6. submission_attachment：学生ID → INT（可空）
+-- ---------------------------------------------------------------------
+UPDATE `submission_attachment`
+    SET `student_id` = NULL
+    WHERE `student_id` IS NOT NULL AND `student_id` NOT REGEXP '^[0-9]+$';
+ALTER TABLE `submission_attachment`
+    MODIFY `student_id` INT NULL COMMENT '学生ID（用户中心数字ID）';
+
+-- ---------------------------------------------------------------------
+-- 7. class_student：学生ID → INT（NOT NULL，uk_class_student 不变）
+-- ---------------------------------------------------------------------
+DELETE FROM `class_student` WHERE `student_id` NOT REGEXP '^[0-9]+$';
+ALTER TABLE `class_student`
+    MODIFY `student_id` INT NOT NULL COMMENT '学生ID（用户中心数字ID，即 SchStudent.UserStuSerID）';
+
+-- ---------------------------------------------------------------------
+-- 8. notification：接收人ID → INT（NOT NULL，idx_receiver 不变）
+-- ---------------------------------------------------------------------
+DELETE FROM `notification` WHERE `receiver_id` NOT REGEXP '^[0-9]+$';
+ALTER TABLE `notification`
+    MODIFY `receiver_id` INT NOT NULL COMMENT '接收人ID（学生=student_id，教师=用户中心数字ID，同一 ID 空间）';
+
+-- ---------------------------------------------------------------------
+-- 9. contacts_group：创建人ID → INT（可空）
+-- ---------------------------------------------------------------------
+UPDATE `contacts_group`
+    SET `creator_id` = NULL
+    WHERE `creator_id` IS NOT NULL AND `creator_id` NOT REGEXP '^[0-9]+$';
+ALTER TABLE `contacts_group`
+    MODIFY `creator_id` INT NULL COMMENT '创建人ID（用户中心数字ID，同教师ID空间）';