Build fails with Vite 8 `experimental.bundledDev`

[heiwen]

Reproduction

Minimal Reproduction

# 1. Scaffold
bunx create-react-router@latest repro --template remix-run/react-router-templates/minimal --yes
cd repro

# 2. Upgrade to Vite 8
bun add -d vite@^8.0.3

# 3. Enable bundledDev in vite.config.ts
cat > vite.config.ts << 'EOF'
import { reactRouter } from "@react-router/dev/vite";
import { defineConfig } from "vite";

export default defineConfig({
  experimental: { bundledDev: true },
  plugins: [reactRouter()],
});
EOF

# 4. Run dev
bunx react-router dev

Expected

Dev server starts normally.

Actual

Build fails with parse errors from es-module-lexer. Every .tsx route file triggers failures because the lexer receives untransformed TSX/TypeScript source.

Cause

The react-router:build-client-route plugin calls es-module-lexer in its transform hook to detect route exports (loader, action, default, etc.):

// @react-router/dev — build-client-route plugin
const [, exportSpecifiers] = esModuleLexer(code);

In standard dev mode, Vite's unbundled pipeline transpiles TSX → JS before this hook runs. In experimental.bundledDev, Rolldown feeds raw .tsx source to the plugin before any transpilation, and es-module-lexer cannot parse TypeScript/JSX syntax.

Environment

• React Router: 7.14.0
• Vite: 8.0.x
• No additional plugins required — the default template is enough to reproduce

Possible Fixes

• Replace es-module-lexer with Oxc parser for export detection (already a Vite 8/Rolldown dependency, handles TS/TSX natively)
• Pre-strip types before lexing (e.g., oxc-transform) when bundled dev is detected
• Defer export analysis until after the transform pipeline has transpiled the source