Stack modernization: Gatsby → Astro (Vite) + Bun + Biome

[davidbarna]

Full stack modernization in a single PR: Bun as runtime/package manager, Biome for lint + format, and Vite as the builder via Astro 5 (Gatsby has no Vite support, so the framework is replaced). All 12 Playwright e2e specs pass unchanged against the new stack.

What changed

Toolchain

• npm → Bun: bun.lock replaces the lockfileVersion-1 package-lock.json; no more --legacy-peer-deps (the @atlaskit packages that forced it are gone)
• Biome (net-new linting + formatting, replaces the unused .prettierrc); bun run lint / bun run format, wired into CI
• Gatsby 5 → Astro 5 (Vite): content collection globs the src/md wiki subtree in place — the wiki:add|pull|push subtree scripts are untouched

URLs preserved

/docs/<slug> and /slides/<slug> under the /js-training base path are byte-identical (same camelCase→kebab slugify, same directory-format output), so existing links keep working. Since Astro doesn't auto-prefix links like Gatsby's <Link>, all internal hrefs go through a withBase() helper — and dev/preview also serve under the base path, so a missing prefix fails locally, not just in production.

Slideshows: reveal.js 3.7 → 5.2

• RevealDeck.tsx React island renders .reveal > .slides > section in-tree and calls new Reveal(el, config).initialize() / destroy() — replaces the old createPortal/body-DOM/head.min.js hack
• Slide markdown is rendered to HTML at build time (unified: remark-gfm + rehype-raw, the same chain react-markdown used) with Shiki highlighting — prismjs 1.15 and the manual Prism.highlight DOM walk are gone
• Custom theme still compiles from the reveal.js theme template (shipped in the reveal 5 npm package); exercise/solution/important slide variants, speaker notes (S), parallax background, and slide numbers all verified working
• Dead multiplex/socket.io/now.sh CDN config removed (the multiplex plugin was removed in reveal 4.x and its server is long dead)

Docs pages

Astro's built-in markdown + Shiki inside .markdown-body (github-markdown-css) — replaces react-markdown + react-syntax-highlighter with zero client JS. External links open in new tabs via rehype-external-links (replacing the old global <base target="_blank">, which would have broken sidebar navigation).

Navigation

The whole @atlaskit/* suite (navigation-next, button, icon, logo, theme + SSR mocks + webpack aliases) is replaced by a lightweight Astro sidebar with the same gold branding, section grouping from constants.ts, and active-link state.

Dead code removed (verified unreachable before deletion)

• firebase v8 auth: the sign-in UI imports material-ui, which isn't even in package.json — it could never compile, and nothing live imported it. Its only purpose was gating reveal multiplex "teacher mode" against a dead server.
• react-intl (zero usages), @reach/router, CRA-era src/index.js/index.html, components importing uninstalled react-helmet, broken nav components, stale one-off scripts, the sui-mono package.json block
• emotion v10 + styled-components v6 → Astro scoped styles + Sass (one styling system)

Fixed along the way

Markdown images referenced as /images/... resolved to the domain root and were broken in production under the /js-training prefix; a small remark plugin now prefixes them with the base path at build time.

Kept

• three.js homepage hero (decorative cube-logo animation) as a lazy client:idle island, still pinned to three 0.70 — porting to current three.js is deliberate follow-up work
• MarkdownParser.ts slide-splitting logic reused verbatim (e2e slide ids depend on it)
• Playwright e2e suite unchanged except baseURL/webServer config

CI/CD

• Both workflows on oven-sh/setup-bun@v2 + bun install --frozen-lockfile
• deploy.yml publishes dist/ via peaceiris (no repo-settings change needed); Gatsby caches, the sharp toolchain, and the NODE_OPTIONS heap bump are gone
• e2e.yml gains a Biome lint gate
• The dead Universal Analytics tag (UA-146160304-1) was dropped

Numbers

• 141 files changed, +2,141 / −23,369
• 27 runtime/build dependencies removed; build produces 44 static pages in ~18s
• 12/12 e2e specs green (home, docs, slideshow) against astro preview, verified from a cold build

Follow-up candidates

• Port src/packages/three-background to current three.js (or replace with static art)
• TypeScript strict via astro/tsconfigs/strict + astro check in CI
• Optional: switch deploy to actions/deploy-pages (requires flipping the repo's Pages source to "GitHub Actions"), @astrojs/sitemap, OG meta

🤖 Generated with Claude Code

https://claude.ai/code/session_015wQX6V9ysFXjaHYAdF8fHJ

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