Before your comment, my design could not do that. After your comment, I'll make sure it will. As a build system, it can incorporate other build systems and run

Before your comment, my design could not do that. After your comment, I'll make sure it will. As a build system, it can incorporate other build systems and run them natively. It only makes sense that it should do that for package managers as a package manager. So as long as you understand that most other build systems give you opaque binaries, I can make that happen. But on the other hand, I think I can make your mutable environment idea work and cross-platform to. My design will require that the environments all be on the same disk because it will use hard links and a SQLite database, but those work on any platform. But anyway, I also think I could set up mutable environments such that, as long as you only modify it through my tool, it could record those modifications and generate a file to recreate that environment elsewhere. That sounds like Nix, but again, my tool will use other build systems and package managers. Is that what you want? Or did I read it wrong?