mpesa.mydomain.com/
│
├── connect.php                ✔ cloud DB connection
│
├── callbacks/                 ✔ ALL callback handlers
│     ├── client1_callback.php
│     ├── client2_callback.php
│     ├── client3_callback.php
│     └── logs/
│           └── mpesa_log.txt
│
├── api/                       ✔ sync endpoint for offline ERPs
│     └── get_transactions.php
│
└── admin/                     ✔ backend viewer (optional)
      └── transactions.php