Thriftledger: bank accounts, budgets and spending reports for a household
Bank accounts, CSV import that skips duplicates, rules that categorize, monthly budgets and spending reports.
Agent specs
- Agent
- Claude Code, Opus 5.5 Medium
- Time
- 24 min
- Cost
- $8.30*
Agents work faster and more accurately on Elements.
* Cost at API rates, September 2026.
Run it yourself
Paste this prompt into your AI agent. You get the finished app on your own machine, ready to change however you like.
Install elements: curl -fsSL 'https://install.elements.dev?os=darwin' | sh && export PATH=~/elements/bin:$PATH Create an Elements app from the elementscode/demo-thriftledger scaffold: cd ~/elements/projects elements create thriftledger -scaffold=elementscode/demo-thriftledger cd thriftledger Start the app.
How it's built
Thriftledger needed a ledger that stays current in every open tab, a CSV importer that knows what it has already seen, rules that sort spending, and budgets that move as transactions arrive. Each of those is a part of Elements, so the agent spent its 24 minutes on the money itself.
What Elements gave the app
- A live ledger. Accounts, categories, rules, budgets, imports and transactions are LiveTables, each opened for the signed-in household. A trigger carries every transaction write to the open pages, so the dashboard's budgets move the moment an import lands in another tab.
- CSV import as a function call. The import page previews the file in the browser, then sends it to an
@rpcthat parses the rows on the server and inserts them in one transaction. Each row carries a fingerprint, so a re-import skips what is already there, and the column mapping is saved for that bank's next export. - Rules that categorize. Every imported row takes the longest matching rule, and one rpc runs the rules over everything still uncategorized in a single SQL update. Edits go through the transactions LiveTable, which checks that a split's parts add up to the whole.
- Reports from the data. The reports page draws its spending charts as SVG from the ledger's own rows.
- Data from SQL files. Two migrations define the ledger and seed one household with three accounts, categories, rules, budgets and six months of activity ending today.
What the project server gave the agent
The project server runs alongside the agent and answers as soon as a file is saved: it type-checks the templates, TypeScript and SQL, applies migrations and reruns the tests, so every question came back right away and the agent kept building.
What shipped
The app type-checks with zero errors and all 28 tests pass. Every page works on desktop and phone, and live updates arrive across tabs, such as a budget that moves when an import lands.
The code
Build it from scratch
To watch your agent build this app from an empty project, use the prompt we used instead. It takes longer than starting from the finished app above.
Install elements: curl -fsSL 'https://install.elements.dev?os=darwin' | sh && export PATH=~/elements/bin:$PATH Create an Elements app: cd ~/elements/projects elements create thriftledger cd thriftledger Start the app, then build this: Build a personal budgeting app named thriftledger. - Accounts. Add bank accounts (checking, savings, credit card). - Import transactions from a bank CSV export: map the date, description and amount columns once per account, and skip duplicates. - Categorize transactions; rules that categorize by description automatically. - A monthly budget per category, with spent and remaining. - Reports: spending by category (donut), income versus spending by month (bars), and net worth over time. - Split a transaction across categories. Seed one user with three accounts, six months of realistic transactions, categories, rules and budgets. Show the seeded login on the sign-in page. Budgets and reports update in real time as transactions are imported and categorized.
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