HOTFIX XAC NHAN GIAO SACH - 18/09/2026

Loi: "Sach co hang da giu rieng cho doi sach; khong the dung cho giao thuong..."
Dieu kien cu chan ca khi recallProtected = 0, khien canh bao giu cho va
luong xac nhan ton am khong duoc thuc thi.

GOI NAY CHI THAY 1 FILE MA NGUON:
api/confirm_delivery.php
Khong co config, .env, SQL hoac du lieu khach hang.

CAP NHAT NHANH:
1. Sao luu file mua-sach/api/confirm_delivery.php tren hosting.
2. Giai nen ZIP. Ghi de api/confirm_delivery.php vao DUNG thu muc
   mua-sach/api/confirm_delivery.php cua website dang chay.
3. Trong file tren hosting, kiem tra dieu kien:
   if ($recallProtected > 0 && $deduction > 0 && $after < $reservedAfter+$recallProtected)
4. Neu van hien nguyen cau loi cu, reset PHP OPcache / restart PHP
   bang bang dieu khien hosting. Ctrl+F5 chi xoa cache trinh duyet,
   khong dam bao xoa cache ma PHP tren may chu.
5. Tra cuu lai don de kiem tra tinh trang da giao truoc khi xac nhan tiep.

HANH VI SAU SUA:
- Khong co hang giu doi: cho di tiep qua luong giao thuong.
- Ton am: van can quyen ngoai le, xac nhan va ly do theo luong hien tai.
- Co hang giu doi thuc su: van bao ve so luong nay, thong bao ro tua sach
  va so lieu neu giao thuong vuot muc.
- Van chan cac tua nam trong bien ban thu hoi ACTIVE.

Goi hotfix khong thay giao dien. Goi day du da cung cap:
ufm-recall-delivery-guard-fix-20260918-v1.zip
Goi day du bo sung hien thi hang giu doi va gioi han so luong tai man tra cuu.

Da kiem thu logic PHP, JavaScript va doi chieu gioi han voi guard may chu.
Chua trien khai hoac kiem thu giao dich thuc te tren hosting.
