Is it safe to delete .Rproj.user?

Does .Rproj.user just store temporary session information? Is it generally safe to delete it?

I am trying to clean up on a computer with limited space. I see that one of my .Rproj.user directories is using 389MB. Most of this (364MB) is taken by a single subdirectory in .Rproj.user/shared/notebooks. I tried to figure out what is stored here, but the files are all binary and searching the RStudio docs and the internet in general don't provide a lot of information.

I'm using Rstudio Version 1.1.383