Lucas WintherandClaude Opus 5
a159189b01
The density the owner chose. Newest day first, weekday named because that is
what a person recognises, and order within a day preserved so a row just
entered stays where it was put.
Two cases the obvious implementation gets wrong, both tested:
A finance plan's later slices belong in this month — money moves this month —
but the purchase's own date does not. Filing them by date would have put
"14 August" inside the September list, so they group separately, last, under
"Financed from earlier months".
A purchase date may legally be "YYYY-MM" with no day at all, which gets its
own trailing group rather than a heading reading "NaN".
The weekday is computed in UTC on both ends. `new Date("2026-09-01")` parses
as UTC midnight, so `getDay()` anywhere west of Greenwich reports the previous
day and every heading would be wrong by one for the user. A test pins three
timezones.
Trade-off worth stating: headings cost vertical space on a day with a single
purchase, and only pay for themselves when a day has several. PRODUCT.md says
the owner records in batches — "a grocery trip is twenty lines entered in one
sitting" — so real data should sit on the paying side of that.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Budget 2.0
A personal budgeting PWA. Envelope-style monthly budgets with rollover, split purchases, finance plans, multi-currency, and JSON/ODS export. All data lives in your browser — there is no server and no account.
Development
bun install
bun --hot src/index.ts # dev server with hot reload
bun test # run the test suite
bun run build # production build into dist/
Self-hosting with Docker
docker build -t budget2 .
docker run --rm -p 3000:3000 budget2
To serve from a subpath, build and run with BUN_PUBLIC_BASE_PATH:
docker build -t budget2 --build-arg BUN_PUBLIC_BASE_PATH=/budget/ .
docker run --rm -p 3000:3000 -e BUN_PUBLIC_BASE_PATH=/budget/ budget2
GitHub Pages
Pushing to main builds and deploys to Pages automatically, using
/<repository-name>/ as the base path. Enable Pages with "GitHub Actions" as
the source in the repository settings.
Your data
Everything is stored in this browser's IndexedDB. Export regularly from Settings → Your data: the JSON export is both your backup and how you move your budget to another device. Import replaces everything and downloads a backup of your current data first.
Known limitations
- Data is per-browser. There is no account and no sync. If you clear this browser's site data, or move to a different browser or device, your budget is gone unless you exported it first. The JSON export is not just a nice-to-have backup — it is the only way to move a budget between devices.
- The install prompt is incomplete.
manifest.webmanifestcurrently only ships an SVG icon. Chrome requires PNG icons at 192×192 and 512×512 to offer the "Install app" prompt; until those are added, the app works fine as a regular tab but won't be installable on Chrome/Chromium.
Documentation
- Design:
docs/superpowers/specs/2026-09-01-budget-app-design.md - Implementation plan:
docs/superpowers/plans/2026-09-01-budget-app.md