Workflow Automation ยท A small import reseller
From a WhatsApp message to a numbered PDF receipt
The owner already ran the business on WhatsApp. Typing receipts by hand was the slow part. Now the order details go into a chat message and the receipt comes back in the same chat.
What we built.
The owner sends the order
Items, prices, shipping and delivery fee, typed the way the owner already writes them.
AI reads it into line items
The message is interpreted into structured items. The AI reads; it does not do the arithmetic.
Totals are calculated in code
Every total is computed by the workflow, so a misread number cannot quietly change the amount.
A receipt number is reserved
Numbering is atomic against the ledger, so no two receipts share a number.
The PDF is rendered and sent
A branded PDF is generated, delivered back into the chat, and the delivery is logged.
Built to hold up.
Arithmetic is never the AI's job
Testing caught a model double-counting a line, so totals moved into code.
No duplicate numbers
Receipt numbers are reserved before any PDF is made.
Its own database
Receipts live in their own database and role, apart from other workloads on the same server.
Every send is recorded
Delivery is logged, so a missing receipt can be traced.
Where it stands.
- A complete run from a real WhatsApp message to a delivered PDF receipt.
- Totals calculated in code, with atomic numbering.
What we measure next.
- Weekly transaction volume
- How often a receipt needs correcting
- Time per receipt, before and after
Runs on
- n8n
- WhatsApp Cloud API
- Claude (Anthropic API)
- Gotenberg
- PostgreSQL
Tell us what needs to happen.
Thirty minutes, your agenda. You leave with a first step whether or not we work together.
omari@monosolution.xyz+1 213 556 4010