Split a group purchase into per-person statements from orders and invoices

Zupanič organised a combined purchase among friends. Orders came in by message and email and were collected in a spreadsheet; the supplier and the transporter sent separate bills. Zupanič first explained the spreadsheet columns to Codex and gave it the documents, and it wrote programs to process the orders and produce reports. That became a set of instructions, which Zupanič then tested in an ordinary free Claude chat: uploading the instructions, the order spreadsheet and photos of the delivery note and the supplier's invoice, and answering Claude's questions as they came up. The conversation was in Slovenian.

Claude noticed the spreadsheet held two versions of the orders and asked which was current. It found 9 of the 162 ordered boxes were never delivered, across four products, and left them off everyone's bill. It caught that orders were in boxes while invoice prices were per piece. It asked how to share the €157.89 transport and split it by each person's goods total, adjusting rounding to match the bill. Goods came to €2,256.44, €2,414.33 with transport. It produced a spreadsheet and a PDF with one page per participant, plus scripts and a state file. Zupanič checked the results and found them correct, all within the free tier.

The free usage limit was hit only afterwards, on a request for a PDF of the conversation itself. The post ends with an ad for the author's paid toolkit. The organiser still has to check the physical delivery and decide things like deposits and how to share costs.