Build a personal finance manager, one honest feature at a time. Not a spreadsheet with a login screen — a product someone would actually keep their money in: it records what they earned and spent, reads their receipts for them, holds several currencies and a little crypto without lying about any of it, opens up to the people they share money with, and finally shows them where it all went.

Six sessions, one codebase. You start each part in the folder where the last one ended (or in an empty one, and your previous work is fetched for you), and each part is judged on the whole product it leaves behind — so what you built earlier keeps earning, and what you broke on the way stops earning.

What every part shares

The money is the contract. Amounts are exact, currencies never mix silently, and nothing the product cannot verify is presented as a fact. Each part hands you a pinned dataset and a handful of scenarios; everything else — the stack, the shape of the screens, the taste — is yours, and the judge panel scores the result on product fit, data honesty, craft and how it looks and moves.

The parts

1. The Ledger — money in and money out: record it, correct it, delete it, see what is left, and refuse the entries that make no sense.
2. Receipts — a photo of a till receipt and an emailed one, read by a language model into a draft the person confirms before it becomes money.
3. Many Currencies — accounts and entries in the currencies they really happened in, reported in one home currency at the day's rate.
4. Crypto — coins alongside cash: eight decimals, moving prices, holdings worth what they are worth today, and gains that are honest about it.
5. Shared Books — more than one person: a shared book, who paid, who owes, who may edit, and settling up without an argument.
6. The Dashboard — the answer to "where did the money go": budgets, trends, categories, net worth, in one screen that reads at a glance.