Run SPA in sub path

[khanhicetea]

Hi I wondering that , is it possible to run SPA in the subpath like /app :

• /app => SPA
• /api => API
• /* : public assets or SSR

I tried this config but some weird error in dev mode ( the index root is using spa index.html ) and build mode ( not found './routes' in spa building )

import { defineConfig } from '@tanstack/start/config'
import tsConfigPaths from 'vite-tsconfig-paths'
import reactRefresh from '@vitejs/plugin-react'
import { TanStackRouterVite } from '@tanstack/router-plugin/vite'

const appConfig = defineConfig({
  tsr: {
    appDirectory: 'pages',
  },
  vite: {
    plugins: [
      tsConfigPaths({ projects: ['./tsconfig.json'] }),
    ],
  },
})

appConfig.addRouter({
  name: 'spa-app',
  type: 'spa',
  base: '/app',
  handler: './index.html',
  root: "spa",
  target: "browser",
  plugins: () => [
    tsConfigPaths(),
    TanStackRouterVite({
      routesDirectory: './routes',
      generatedRouteTree: './routeTree.gen.ts',
      autoCodeSplitting: true,
    }),
    reactRefresh()
  ],
});

export default appConfig;

Below is my file tree structure: