First time poster, long time lurker, searched, couldn’t find etc, etc.

I’m running vim in tmux, in iTerm2. I’m running a server with Grunt.js, which I have running in the background, out of my way. I start my grunt server in the background like this:

grunt server &

Grunt also watches a bunch of files, and runs some tasks when any of the watched files have been written to. The problem is, when I am in vim and I write a file, the output from grunt starts rendering in vim! Here are some screenshots to illustrate the problem:

Before writing the file:

And after writing the file:

What have I tried?

I’ve tried running a ‘stock’ vim by starting with this:

vim -u NONE

…But the problem remains. This suggests to me that the problem is not with my .vimrc. Perhaps it’s an issue with iTerm2, I don’t know. Help.