Ahha, the context about context has come back to me. The reason I store the context here is so that we can ensure that we call post with a CSRF token without requiring a higher level caller to worry about calling session_context and passing the token from user.js->network.js->xhr.js. 

This seems like a heavy handed way of going about things that leads to too much context lying around. 
Perhaps a better way is to have network.js take care of automatically fetching session_context before any posts, then set the CSRF token in xhr.js? If a post is attempted without a CSRF token, xhr throws an exception? I agree, context should not be here.