Some frameworks bake env vars into the output at build time rather than reading them at runtime. Vite is the obvious example: anything prefixed VITE_ gets inlined into the bundle when vite build runs. Until now Suga only supported runtime env vars, so frameworks that needed values during the build couldn't see them.
You can now set build-time env vars on any service, available for both auto-detect and Dockerfile builds. Custom build and start commands are also configurable for auto-detect, so you can override what Suga's framework detection picked if it didn't match what your project actually does.