diff --git a/db_migrations/phase14_defective_goods_location_snapshot.sql b/db_migrations/phase14_defective_goods_location_snapshot.sql
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+-- =============================================================================
+-- 不良品在管台账：补「原库位 / 批次(序列号)」快照列
+--
+-- 背景
+--   trans_defective_goods 只冗余了 material_name / spec_model，却没有存库位与
+--   批次。于是报废台账页、报废申请单明细上，凡是不良品来源的行，库位与
+--   批次一律显示 "-" —— 而它们的源库存行往往**还在**，本该取得到。
+--
+--   应用层原先的处置是在 _resolve_materials 与 DefectiveScrapAdapter.snapshot
+--   里直接硬编码空串，注释理由是「源库存行可能已被物理删除」。这个担忧对
+--   material_name/spec_model 成立（所以它们有冗余快照），但库位/批次**没有**
+--   快照列，一律置空等于放弃了「源行还在」这个绝大多数情形。
+--
+-- 本次改动（A+B）
+--   A. 应用层改为「快照优先 + 回查源库存行兜底」（本次只加列，逻辑在代码侧）
+--   B. 本文件补两列，把「源行可能被删」这个担忧真正解决掉：退回那一刻
+--      stock_row 已 with_for_update() 锁在手里，库位/批次随手可取，
+--      落库后即使源行日后被物理删除，报表依然有值。
+--
+-- 口径（2026-09-23 与业务确认）
+--   存的是「**原库位**」—— 这批货最初在哪，而不是坏件当前所在的不良品区。
+--   与三张库存表来源的报废记录口径一致。不良品区的位置本系统未记录。
+--
+--   ★ batch_number 列对 stock_product 来源存的是 serial_number：
+--     成品表没有 batch_number 列（见 information_schema），取值口径沿用
+--     应用层的 COALESCE(batch_number, serial_number)，与 _from_stock 一致。
+--     故本列语义为「批次或序列号」，与前端列名「批次/序列号」对齐。
+--
+-- 安全性：纯追加式 DDL，无 NOT NULL、无 DEFAULT，既有行取值 NULL。
+-- 幂等：IF NOT EXISTS + 带 WHERE 的 UPDATE，可重复执行。
+--
+-- 执行
+--   docker exec -i inventory_db psql -U test -d inventory_system < 本文件
+-- =============================================================================
+
+BEGIN;
+
+-- ---------------------------------------------------------------------------
+-- 1) 快照列（长度与三张库存表对齐，均为 varchar(100)）
+-- ---------------------------------------------------------------------------
+ALTER TABLE trans_defective_goods
+    ADD COLUMN IF NOT EXISTS warehouse_location varchar(100),
+    ADD COLUMN IF NOT EXISTS batch_number       varchar(100);
+
+COMMENT ON COLUMN trans_defective_goods.warehouse_location IS
+    '原库位快照（退回时取自源库存行）。源行被物理删除时此处仍有值，故报表优先用它';
+COMMENT ON COLUMN trans_defective_goods.batch_number IS
+    '批次/序列号快照（退回时取自源库存行的 batch_number，成品表缺失时取 serial_number）';
+
+-- ---------------------------------------------------------------------------
+-- 2) 存量回填：按 source_table + stock_id 回查源库存行
+--    三张表分别 UPDATE（多态关联，无法用一条语句表达）。
+--    WHERE warehouse_location IS NULL 保证幂等，且不覆盖已回填过的值。
+--
+--    回填不到的（源行已被物理删除）保持 NULL —— 刻意不写成空串，
+--    这样下面的核对能数出「真正取不到」的行数，与「已确认无库位」区分开。
+-- ---------------------------------------------------------------------------
+UPDATE trans_defective_goods g
+   SET warehouse_location = COALESCE(b.warehouse_location, ''),
+       batch_number       = COALESCE(NULLIF(b.batch_number, ''), b.serial_number, '')
+  FROM stock_buy b
+ WHERE g.source_table = 'stock_buy'
+   AND g.stock_id = b.id
+   AND g.warehouse_location IS NULL;
+
+UPDATE trans_defective_goods g
+   SET warehouse_location = COALESCE(s.warehouse_location, ''),
+       batch_number       = COALESCE(NULLIF(s.batch_number, ''), s.serial_number, '')
+  FROM stock_semi s
+ WHERE g.source_table = 'stock_semi'
+   AND g.stock_id = s.id
+   AND g.warehouse_location IS NULL;
+
+-- ★ 成品表无 batch_number 列，只取 serial_number
+UPDATE trans_defective_goods g
+   SET warehouse_location = COALESCE(p.warehouse_location, ''),
+       batch_number       = COALESCE(p.serial_number, '')
+  FROM stock_product p
+ WHERE g.source_table = 'stock_product'
+   AND g.stock_id = p.id
+   AND g.warehouse_location IS NULL;
+
+COMMIT;
+
+
+-- =============================================================================
+-- 执行后核对
+-- =============================================================================
+SELECT '=== 1) 回填结果：已回填 / 源行已删取不到 / 无需回填 ===' AS "核对项";
+SELECT count(*) FILTER (WHERE warehouse_location IS NOT NULL) AS 已回填,
+       count(*) FILTER (WHERE warehouse_location IS NULL)     AS 源行已删_取不到,
+       count(*)                                               AS 台账总行数
+  FROM trans_defective_goods;
+
+SELECT '=== 2) ★ 源行已删的明细（取不到库位属预期，应逐条确认是否为真）===' AS "核对项";
+SELECT id, source_table, stock_id, sku, status
+  FROM trans_defective_goods
+ WHERE warehouse_location IS NULL
+ ORDER BY id;
+
+
+-- =============================================================================
+-- 回滚段（仅撤销本迁移；回填值与「原本就是空」无法区分）
+-- =============================================================================
+-- BEGIN;
+-- ALTER TABLE trans_defective_goods DROP COLUMN IF EXISTS warehouse_location;
+-- ALTER TABLE trans_defective_goods DROP COLUMN IF EXISTS batch_number;
+-- COMMIT;