Configure public base url after building?

[Blakeinstein]

I currently use https://import-meta-env.org/ to support replacing variables after building so that my CI can keep building tarballs, and the only thing my deployment service is worried about is using their CLI to update the vars and push to Apache.

This worked great so far, but now that I need to deploy multiple versions of the project, like 1. devtest 2. production and 3. sprint preview , I have a weird issue. We use the same domain and server for all three versions but on different paths.
/project-devtest for devtest, /project for production, and /project-{sprint} for sprint previews. The existing approach cannot configure Vite's base path on the built code. Can I avoid needing my deployment server to build the front end from scratch?