[flukus]

What works for me is having a script per project/directory a script that set all the configs (as environment variables) and various other functions for that project. If the script exists then it runs when I cd in and other scripts can use the environment variables. So a script like start-language-server would check for the environment variable PYTHONLS and PYTHONLSPORT and start it if it's not running, or it can be started straight from the cd.

Never had to handle multiple languages in one project though, I find vims builtin completion enough for the rest.