Lucas Winther
26752aa225
bun init --react=shadcn, with the demo API routes removed since this app has no backend. Adds project invariants to CLAUDE.md and a smoke test proving the domain layer imports with no DOM.
123 lines
3.4 KiB
Markdown
123 lines
3.4 KiB
Markdown
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Default to using Bun instead of Node.js.
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- Use `bun <file>` instead of `node <file>` or `ts-node <file>`
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- Use `bun test` instead of `jest` or `vitest`
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- Use `bun build <file.html|file.ts|file.css>` instead of `webpack` or `esbuild`
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- Use `bun install` instead of `npm install` or `yarn install` or `pnpm install`
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- Use `bun run <script>` instead of `npm run <script>` or `yarn run <script>` or `pnpm run <script>`
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- Use `bunx <package> <command>` instead of `npx <package> <command>`
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- Bun automatically loads .env, so don't use dotenv.
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## APIs
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- `Bun.serve()` supports WebSockets, HTTPS, and routes. Don't use `express`.
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- `bun:sqlite` for SQLite. Don't use `better-sqlite3`.
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- `Bun.redis` for Redis. Don't use `ioredis`.
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- `Bun.sql` for Postgres. Don't use `pg` or `postgres.js`.
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- `WebSocket` is built-in. Don't use `ws`.
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- Prefer `Bun.file` over `node:fs`'s readFile/writeFile
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- Bun.$`ls` instead of execa.
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## Testing
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Use `bun test` to run tests.
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```ts#index.test.ts
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import { test, expect } from "bun:test";
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test("hello world", () => {
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expect(1).toBe(1);
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});
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```
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## Frontend
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Use HTML imports with `Bun.serve()`. Don't use `vite`. HTML imports fully support React, CSS, Tailwind.
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Server:
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```ts#index.ts
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import index from "./index.html"
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Bun.serve({
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routes: {
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"/": index,
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"/api/users/:id": {
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GET: (req) => {
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return new Response(JSON.stringify({ id: req.params.id }));
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},
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},
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},
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// optional websocket support
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websocket: {
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open: (ws) => {
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ws.send("Hello, world!");
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},
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message: (ws, message) => {
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ws.send(message);
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},
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close: (ws) => {
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// handle close
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}
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},
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development: {
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hmr: true,
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console: true,
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}
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})
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```
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HTML files can import .tsx, .jsx or .js files directly and Bun's bundler will transpile & bundle automatically. `<link>` tags can point to stylesheets and Bun's CSS bundler will bundle.
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```html#index.html
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<html>
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<body>
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<h1>Hello, world!</h1>
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<script type="module" src="./frontend.tsx"></script>
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</body>
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</html>
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```
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With the following `frontend.tsx`:
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```tsx#frontend.tsx
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import React from "react";
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import { createRoot } from "react-dom/client";
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// import .css files directly and it works
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import './index.css';
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const root = createRoot(document.body);
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export default function Frontend() {
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return <h1>Hello, world!</h1>;
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}
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root.render(<Frontend />);
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```
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Then, run index.ts
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```sh
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bun --hot ./index.ts
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```
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For more information, read the Bun API docs in `node_modules/bun-types/docs/**.mdx`.
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## Project invariants (Budget 2.0)
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- `src/domain/` is pure: no React, no IndexedDB, no `Date.now()`, no `new Date()`
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without an explicit argument. It must be testable with no DOM.
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- Money is a float. Always round with `roundMoney` from `src/domain/money.ts`
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after any division, after any FX conversion, and before persisting.
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- When splitting an amount, never round the last part independently. Compute it
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as `total - sum(others)` so the parts sum exactly to the whole.
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- `MonthId` is the string `"YYYY-MM"`. Stored data never contains `Date` objects.
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- The envelope rollover fold has exactly one implementation, in
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`src/domain/fold.ts`. Year and summary views aggregate over it — they never
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reimplement the math.
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- Over-budget is always allowed. Never add validation that blocks it.
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- Base path comes from `BUN_PUBLIC_BASE_PATH`; never hardcode a subpath.
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- Read the spec at `docs/superpowers/specs/2026-09-01-budget-app-design.md`.
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