Vite 8.1 + Rolldown 1.1.2 upgrade, with experimental bundled dev mode (off by default)

[natew]

Summary

Upgrades One to Vite 8.1.0 + Rolldown 1.1.2, and adds an experimental bundled dev mode (Vite's FullBundleDevEnvironment) behind an opt-in flag:

one({ web: { experimentalBundledDev: true } })

The upgrade itself (normal/unbundled dev + prod builds) is the shippable win. Bundled dev mode is wired up and renders/hydrates, but has known upstream blockers documented below — it's off by default and should stay that way until those land.

Why upgrade (independent of bundled mode)

Vite 8's headline is Rolldown becoming the single Rust bundler (replaces Rollup + esbuild):

• ~10–30× faster production builds (Rust)
• Oxc-powered transforms/minify (@vitejs/plugin-react v6)
• Unified bundler for dep pre-bundling + build → fewer dev/prod drift surprises

Normal dev is unchanged vs Vite 7, so the build-side win lands regardless of dev mode.

Bundled dev mode — what it is

A single rolldown-powered client bundle in dev instead of unbundled ESM (~4× fewer requests). Four One-specific problems had to be solved to make it work (asset-import inlining, lazyBarrel off, shimMissingExports, react-refresh preamble) — see notes/vite-8.1-bundleddev-findings.md and bundledDevPlugin.ts. All new code paths are gated on the flag; normal dev is unaffected.

Verified: homepage + routes render & hydrate, client <Link> nav + browser back/forward work, 0 console errors (one-basic + tamagui.dev, cold + warm).

⚠️ Findings: bundled mode is NOT production-ready (3 upstream blockers)

All three live in the vite / rolldown bundled-dev substrate, not One, and none affect prod builds — bundledDevPlugin is gated on command === 'serve', so production output is untouched.

1. HMR is broken and crashes the dev server (blocker) — upstream Vite 8.1.0 bug

Live-tested (playwright, edit a file, browser connected, no reload): the edit (a) never applies to the DOM — Fast Refresh is dead — and (b) crashes the whole dev server seconds later with RangeError: Maximum call stack size exceeded (exit 7). Root cause is stock vite 8.1.0 DevEnvironment.invalidateModule:

invalidateModule(m, _client) {
  if (this.bundledDev) { this.invalidateModule(m, _client); return; }  // self-recurses → stack overflow
  ... // the real HMR invalidation logic only runs on the non-bundledDev path
}

Confirmed contrast: normal (unbundled) dev on this same branch applies edits and the server stays up (Fast Refresh works, 0 errors); with no browser attached the edit doesn't crash (the crash needs a connected client to send the invalidate). Needs an upstream vite fix (or a local patch-package) before bundled dev is daily-usable.

2. matchMedia "Illegal invocation" on cold load — rolldown interop codegen

@tamagui/web's matchMedia helper re-exports the unbound native window.matchMedia. Rolldown's bundled-dev interop compiles the call as ns.matchMedia(q) (this = module namespace) instead of the detached (0, ns.matchMedia)(q) form normal bundlers emit, so native matchMedia throws. Worked around in tamagui with window.matchMedia?.bind(window) (defensive, harmless, worth upstreaming) — but it's a symptom: any const fn = window.nativeThing re-export trips the same bug. Not needed for normal dev / prod builds.

3. __toCommonJS(undefined) cold race on heavily-lazy-split routes — rolldown runtime

/takeout's React.lazy 3D box throws on cold first load from the generated rolldown runtime (CJS dep referenced before init across concurrently-loading lazy blobs); self-recovers on reload. Low severity, cold-only.

Recommendation

Land the Vite 8.1 / Rolldown upgrade for the build-side gains. Keep experimentalBundledDev off by default until at least the upstream vite invalidateModule recursion is fixed. One pre-merge validation still worth doing: a Rolldown prod-build smoke test (the matchMedia-class interop could surface in vite build — untested so far).

Files

• packages/one/src/vite/plugins/bundledDevPlugin.ts (new) — asset inliner + bundled client rolldownOptions
• packages/one/src/vite/one.ts, types.ts — wire the flag
• virtualEntryPlugin.ts, fileSystemRouterPlugin.tsx, devtoolsPlugin.ts — refresh preamble / preload / devtools fixes (all gated on the flag)
• examples/one-basic/vite.config.ts — demonstrates the flag via BUNDLED_DEV env
• notes/vite-8.1-bundleddev-findings.md — full writeup

[railway-app]

🚅 Deployed to the one-pr-730 environment in onestack.dev

Service	Status	Web	Updated (UTC)
one	❌ Build Failed (View Logs)	Web	Jun 24, 2026 at 1:54 am