diff --git a/inventory-backend/app/api/v1/inbound/stock.py b/inventory-backend/app/api/v1/inbound/stock.py
index 4a8a716..4d29c05 100644
--- a/inventory-backend/app/api/v1/inbound/stock.py
+++ b/inventory-backend/app/api/v1/inbound/stock.py
@@ -811,7 +811,11 @@ def get_drafts():
             'id': row.draft_id,
             'user_id': row.user_id,
             'uuid': row.uuid,
-            'quantity': float(row.quantity or 1),
+            # ★ 不可写 `or 1`：实盘 0（货架确实空了）是合法且有信息量的值，
+            #   而 0 是 falsy，`0 or 1` 会把它报成 1 —— 前端「重复扫码」提示读
+            #   的就是这个值，库管看到"当前实盘为 1"会以为填错而改成 1，
+            #   真实的盘亏就这么被抹掉了。
+            'quantity': float(row.quantity) if row.quantity is not None else 0,
             'scan_time': row.scan_time.strftime('%Y-%m-%d %H:%M:%S') if row.scan_time else None,
             'session_id': row.session_id,
             'source_table': row.source_table,
diff --git a/inventory-backend/app/models/inbound/stocktake.py b/inventory-backend/app/models/inbound/stocktake.py
index a804eea..d0eb18d 100644
--- a/inventory-backend/app/models/inbound/stocktake.py
+++ b/inventory-backend/app/models/inbound/stocktake.py
@@ -95,7 +95,8 @@ class StocktakeDraft(db.Model):
             'id': self.id,
             'user_id': self.user_id,
             'uuid': self.uuid,
-            'quantity': float(self.quantity or 1),
+            # ★ 同 stock.py 的 /draft/list：0 是合法实盘值，`or 1` 会把它变成 1
+            'quantity': float(self.quantity) if self.quantity is not None else 0,
             'scan_time': self.scan_time.strftime('%Y-%m-%d %H:%M:%S') if self.scan_time else None,
             'session_id': self.session_id,
             'source_table': self.source_table,