asdf-vm/asdf ? reverse-engineered prompt

Build me a simple command line tool that lets me manage different programming language versions on the same machine and switch them per project.

I want it to feel like one tool for Ruby, Node.js, Python, Elixir, Erlang, and anything else people add later. It should use a plugin style setup so new languages can be added without changing the core app. I’d like one global default version setting, plus a .tool-versions file in each project so the right versions load automatically when I move into a folder. If a project already has files like .nvmrc, .node-version, or .ruby-version, it should be able to use those too.

Please make it work cleanly from the terminal, with helpful commands for installing, setting, listing, and switching versions, and add shell completion for common shells like Bash, Zsh, Fish, and Elvish. Keep the setup easy to use, and look up current docs online if you need to match common version manager behavior.