The prepaid wallet
In one sentence
Each subscriber has a prepaid wallet they top up in advance; every locked delivery debits it, and MsgBuddy alerts them (on WhatsApp) before the balance runs low.
How the wallet works
The wallet is a running balance, kept as a simple, append-only ledger — a list of top-ups (credits) and charges (debits). The balance is just:
Balance = total credits − total debits
A worked example
Asha subscribes to daily milk at ₹60/day and tops up ₹500:
| Date | Entry | Type | Amount | Balance |
|---|---|---|---|---|
| Mar 1 | Top-up | Credit | +₹500 | ₹500 |
| Mar 2 | Milk delivered | Debit | −₹60 | ₹440 |
| Mar 3 | Milk delivered | Debit | −₹60 | ₹380 |
| Mar 4 | Skipped (before cutoff) | — | ₹0 | ₹380 |
| Mar 5 | Milk delivered | Debit | −₹60 | ₹320 |
| … | ||||
| Mar 9 | Low balance — top-up reminder sent | 🔔 | — | ₹80 |
| Mar 9 | Top-up | Credit | +₹500 | ₹580 |
Notice Mar 4: a skip made before the cutoff costs nothing — no debit at all. Only locked deliveries are charged. (If a delivery is ever cancelled after locking, that can be returned as a credit.)
Never a surprise: low-balance alerts
When the balance dips below a threshold, the customer gets a WhatsApp reminder to top up (sent as a Utility template). This keeps deliveries running smoothly and avoids the awkward “your milk stopped because you ran out of credit” moment.
Topping up
Customers top up from their storefront / reminders. If they enable autopay, top-ups can happen automatically when the balance runs low — no manual step.
Encourage a larger first top-up (say, a month’s worth). Fewer top-up prompts means a smoother experience for the customer and fewer missed deliveries for you. Autopay makes this even more hands-off.
Why append-only?
The ledger only ever adds entries — it never edits or deletes past ones. That makes the wallet auditable and trustworthy: you (and the customer) can always see exactly why the balance is what it is, line by line. It’s the same principle a bank statement uses.
How this connects
- Debits happen when a cycle locks.
- Automatic top-ups come from autopay.
- Low-balance alerts use templates.
Next: the controls customers love — pausing & skipping →.