Re: Determining which plugin is catching a command?

Sort of. You can see which script last mapped a given key sequence with
`:verbose map`. For instance, if you want to find out where the `ys`
mapping from surround.vim was last set, you could do

:verbose map ys

which for me, prints:

n yss <Plug>Yssurround
Last set from ~/dotfiles/.vim/plugin/surround.vim
n ys <Plug>Ysurround
Last set from ~/dotfiles/.vim/plugin/surround.vim

So if some other script is remapping that sequence, you should see it
there.