`nitro/vite` will break down unocss in `tanstack start RC`

Environment

• nitro: 3.0.0-20250925-181710-5191890e
• nodejs: v24.5.0

Reproduction

https://github.com/fisand/f3-app/tree/main/apps/web-tanstack

Describe the bug

If I use nitro/vite to build a tanstack start(RC) APP, it looks like will remove vite:css-post plugin, then the CSS will not generator succefully.

[plugin unocss:global:build:generate] [unocss] failed to find vite:css-post plugin. It might be an internal bug of UnoCSS

Other issue is nitro/vite will not match a 404 route to noFoundComponent in a tanstack start(RC) APP, it will always loading util the APP crash.

node:internal/deps/undici/undici:13484
      Error.captureStackTrace(err);
            ^

TypeError: fetch failed
    at node:internal/deps/undici/undici:13484:13

  [cause]: HeadersTimeoutError: Headers Timeout Error
      at FastTimer.onParserTimeout [as _onTimeout] (/node_modules/.pnpm/undici@7.16.0/node_modules/undici/lib/dispatcher/client-h1.js:757:28)
      at Timeout.onTick [as _onTimeout] (/Users/SYY/Desktop/work/f3-app/node_modules/.pnpm/undici@7.16.0/node_modules/undici/lib/util/timers.js:162:13)
      at listOnTimeout (node:internal/timers:594:17)
      at process.processTimers (node:internal/timers:529:7) {
    code: 'UND_ERR_HEADERS_TIMEOUT'
  }

Additional context

No response

Logs

Start with the linked f3-app reproduction and the nitro/vite integration. Reproduce the UnoCSS build error and the missing-route behavior, then trace how the Vite CSS plugin and TanStack Start 404 route are handled. Done means CSS generates successfully and unmatched routes reach noFoundComponent without hanging.