Design for a personal budgeting PWA replacing a spreadsheet workflow.
Key decisions captured:
- Static SPA, no backend in the data path, so it deploys to both GitHub
Pages and a self-hosted Docker image from one build artifact
- Bun toolchain (bun init --react=shadcn); no Vite, no Electron
- Pure derivation core over an IndexedDB fact store; envelope rollover
makes caching worthless, so every figure is folded from raw facts
- One Purchase entity covers simple, split, and financed purchases, which
is what lets splits and finance plans compose without special-casing
- Money is a float, with mandatory rounding at boundaries and last-part-
by-subtraction so distributed parts sum exactly to the whole
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
