Lucas Winther 0d2aa519b7 docs(recurring): record the invariants and what they cost
Two rules that only review catches, so they go in AGENTS.md §1: occurrences are
computed and never stored, and a confirmation's date and its slot are different
facts. Collapsing the second pair into one field would silently delete the
phone-bill behaviour, which is why it is written down rather than left to the
types.

§2 gets the termination guard. n >= 1 is rejected at both write boundaries
rather than clamped, and the walk throws rather than breaking, because a bill
silently dropped from a budget is worse than a visible error.

Demo data seeds a monthly rent and a 28-day subscription — the second is what
puts two occurrences in one month, which is the case worth looking at. It also
seeds a biweekly cost and a lastCharge-anchored one, so every recurrence kind
and both anchorings show up in Settings and the month view.

DECISIONS.md, PRODUCT.md, ARCHITECTURE.md and TODO.md are updated to match:
schema is at 7, the month view carries a second Projected balance beside
Remaining, and TODO.md records what a week of real use — not a test — will
have to answer.
2026-09-03 19:03:35 +02:00

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.md and GEMINI.md point 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.
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