Lucas WintherandClaude Opus 5
f4223573e4
GBP joins the currencies the app comes with: £, two decimals, and a committed fallback rate of 8.704735 DKK to the pound. build.ts now fetches it too, so a build with a network bakes a live GBP rate and one without still covers it — the coverage check derives from the seed table, so it demanded GBP as soon as the table listed it. The seed table alone would not have delivered this. Baked currencies and rates seed a NEW dataset and nothing else, so an existing dataset would have been left typing the code, name, symbol and decimals by hand. A 4 -> 5 migration adds sterling to a dataset that lacks it, with its rate. Supplying a rate is the one thing the "rates never backstop a cleared rate" rule permits here: it forbids re-supplying a number the owner deleted, not introducing one for a currency they have never had. A GBP the owner already defined, or a GBP rate they already hold, is left exactly as it is — asserted, including the case where their definition is "wrong" (zero decimals), because it is theirs. This exposed a real latent bug. The 2 -> 3 step seeded the live seed-currency table BY REFERENCE, so adding sterling there would have retroactively changed what an old dataset received from a step it had already been through — silently, and only for whoever had not migrated yet. Every step now carries its own frozen copy, and a source-level guard fails the build if a live default is imported again. Scoping that guard took two goes: matching the whole file flagged the comment explaining the rule, and then flagged the frozen local copy that is the fix. Two test fixtures used GBP as their example of an UNSUPPORTED currency and now use CHF, which no seed table lists. Verified in a browser by writing a schemaVersion 4 dataset into IndexedDB and reloading: the currency table gains "British pound / £ / 2" with "manual · 2026-09-02", the post currency selector offers GBP, and the income and post survive untouched. Note for the next person — a migration applies in memory on load and is written back on the next mutation, so reading IndexedDB straight after a reload still shows the OLD version. That is recorded in docs/TODO.md, because it made this verification look like a failure at first. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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 run dev # dev server with hot reload, on :3000
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.
Both destructive actions there — Import, and "Reset everything" — download a backup of your current data before replacing it, and abort if that download fails. Reset puts the app back to a brand-new install: the three starter posts, the DKK/USD/EUR currency table, this month at zero income, no purchases.
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.
- Installing and offline use are unverified. The manifest ships the SVG plus 192×192 and 512×512 PNG icons, and the service worker demonstrably installs, activates and precaches every asset — but nobody has yet confirmed that Chrome offers its "Install app" prompt, or loaded the app with the network actually cut. It works as a regular tab regardless.
Documentation
docs/ARCHITECTURE.md— layers, data flow, and why the non-obvious choices are what they are.docs/PRODUCT.md— who this is for and what must never break.AGENTS.md— the rules for changing this codebase, and the test that catches each one when broken.CLAUDE.mdandGEMINI.mdpoint at it.docs/DECISIONS.md— an index of the choices that shaped the app, and what each was chosen over.docs/TODO.md— what is still queued.docs/specs/— one design document per piece of work, each recording the alternatives that were rejected.docs/plans/— task-by-task implementation plans.