Sorry to post support questions as issues but I did not see this addressed in the README.
Is there any way to have use-package load a package from a git release or compressed tar file, e.g. magit-2.8.0.tar.gz, the magit 2.8.0 release?
If not from git, will use-package detect when I have manually installed a package in my ~/.emacs.d directory and not load it again? Or does use-package only know when packages are loaded by the package manager?
You have several options:
package-install package:load-path@vyp: ooooh, shiny
I'm not far from switching to quelpa!
quelpa-use-package is great, you can keep using use-package like normal, and then when you want to install from source you just add :quelpa t to the relevant use-package form. Or :quelpa (cool-package :fetcher github :repo ...).
This is rather beyond the purview of use-package, but there are extensions that might allow it, as mentioned.
Most helpful comment
quelpa-use-packageis great, you can keep usinguse-packagelike normal, and then when you want to install from source you just add:quelpa tto the relevantuse-packageform. Or:quelpa (cool-package :fetcher github :repo ...).