Some more refinement on what I’ve found. I’d really appreciate it if someone could give a yea/nay on this:
Saved/ – cached/built stuff that can safely be deleted
Binaries/ – built output binaries that can safely be deleted, although you’ll need to re-build some DLLs when re-opening a project
Intermediate/ – theoretically safe to delete the contents of, although some bits and pieces may require re-configuration (and you’ll need to re-generate your visual studio projects at a minimum)
Build/**/FileOpenOrder/ – generated file presumably used to optimize the pak files generated. Safe to delete; gets re-generated (and must be git ignored explicitly)
You’ll want to include these in your backups/source control/whatevers:
Build/
Config/
Content/
Plugins/
Source/
*.sln
*.uproject
*.png (not strictly necessary – used as preview in the launcher)