---
title: "Thriftledger: bank accounts, budgets and spending reports for a household"
author: "@chris"
author_url: https://elements.dev/users/chris
published: 2026-09-30T21:49:48.816Z
url: https://elements.dev/demos/d5rv9p01/thriftledger-bank-accounts-budgets-and-spending-reports-for
kind: post
format: article
---

# Thriftledger: bank accounts, budgets and spending reports for a household

by [@chris](https://elements.dev/users/chris) · 2026-09-30

## Description

Bank accounts, CSV import that skips duplicates, rules that categorize, monthly budgets and spending reports.

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 `@rpc` that 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.