feat: add base path support to TanStack Start

[andremonteiro95]

This PR adds support for specifying a base path for TanStack Start apps, enabling deployment to specific paths.

[vimtor]

thanks for the contribution @andremonteiro95

how did you configure the vite.config.ts?

i'm getting this error when trying your code:

[andremonteiro95]

My vite.config.ts looks like the snippet below.

const config = defineConfig(() => {
  const base = process.env.BASE_PATH || undefined

  return {
    base,
    plugins: [
      devtools(),
      nitro({
        baseURL: base,
        preset: 'aws-lambda'
      }),
      // this is the plugin that enables path aliases
      viteTsConfigPaths({
        projects: ['./tsconfig.json']
      }),
      tanstackStart({
        spa: {
          enabled: true
        }
      }),
      viteReact({
        babel: {
          plugins: ['babel-plugin-react-compiler']
        }
      })
    ]
  }
})

export default config

I generate the BASE_PATH in my SST file just like:

const BASE_PATH = isPermanentStage ? undefined : `/${$app.stage}`

export const web = new sst.aws.TanStackStart('Web', {
  environment: {
    ...(BASE_PATH ? { BASE_PATH } : {})
  },

  // ...
})

[vimtor]

thanks for sharing @andremonteiro95

the pr should be working but the router path doesn't seem to be equal to the baseURL

could you share a screenshot of your pr code working? any ideas why it doesn't work given the screenshot i attached

[andremonteiro95]

From the screenshot alone, I'd guess you're missing the base property of Vite's config - that seems to be the only thing that differs from my config.

[vimtor]

nice catch @andremonteiro95

now the only issue is that JS files are being requested from the base path but instead of the root

[andremonteiro95]

Can you send a reproducible example?