Bootstrap: Vite + React + TS + Tailwind v4 + Biome + Vitest

[unforced]

Why

First PR in the Lens serialization. Gets the foundations in place so each subsequent PR can focus on one user-visible slice — vault client + OAuth, note list, note view, editor, graph, etc. — without re-litigating tooling.

Stack choices

Choice	Why
Bun	Matches the vault's runtime; one less thing to explain to contributors.
Vite 6 + React 19 + TS strict	Current baseline; project-reference tsconfigs keep tsc -b fast.
Tailwind v4	Matches Prism; @theme lets us express the design tokens directly in CSS.
Biome	One tool for lint + format + import-organize. Config is ~20 lines.
Vitest 3 + Testing Library	Vitest 3 aligns with Vite 6 (Vitest 2 pinned to Vite 5, caused type conflicts in the config).

Theme tokens

Palette, typography, and idiom borrowed from parachute.computer so Lens feels like a sibling, not a stranger:

• sage --color-accent: #4a7c59
• warm off-white --color-bg: #faf8f4
• Instrument Serif (display) / DM Sans (body) / JetBrains Mono (code)
• Dark mode wired via @media (prefers-color-scheme: dark) at the theme level. The explicit light/dark toggle lands in the theme-polish PR (Hotfix: header label fallback + VITE_EXPOSE gate #10 in the serialization).

Layout

src/
  app/App.tsx        – placeholder landing
  styles/index.css   – tailwind entry + @theme tokens
  test/setup.ts      – testing-library/jest-dom
  main.tsx           – React entry
vite.config.ts       – build
vitest.config.ts     – test (kept separate to avoid vite/vitest version drift)
tsconfig.{app,node}  – strict references

@/ path alias to src/ for readable imports.

What this PR deliberately does not do

• No vault client, no OAuth, no API calls — PR Vault client + OAuth 2.1 PKCE + multi-vault switcher #2.
• No router — wait until we have more than one route.
• No TanStack Query — wait until we have server state.
• No global state — wait until the store's shape is motivated by a real use case.

Keeping PR #1 small and landable is the point.

Gates

• bun run typecheck — clean
• bun run lint — clean
• bun run test — 2/2 pass (smoke test for the landing shell)
• bun run build — 196 kB JS / 10 kB CSS gzipped
• bun run dev — starts on :5173, entry module transforms

Test plan

• bun install && bun run dev, visit http://localhost:5173, confirm the placeholder renders with the parachute.computer palette
• Check dark mode via system preference
• bun run test — expect 2 passing tests
• bun run build — expect no warnings

🤖 Generated with Claude Code