How it works

What actually happens between a photo of an invoice and a line on a profit and loss statement — and where a person is still in the loop on purpose.

What is doing the work

The pieces we would actually build and run

Layer	What it does	Built with	Why this choice

Why a spreadsheet on its own does not hold up

Core tables

Sheets, honestly

Deliberately, not because the model is weak

The constraints we would rather raise now than discover in month three