As long as we don't have to use a flipchart and write 'Be civil', 'Don't talk over people' and 'Confidentiality' on it like a management training course!
The problem is 'commonly agreed upon', there are probably only about 3 or 4 of us on here coming from a more Conservative viewpoint, and so common agreement would always be able to be met by a majority without us being part of that.  Then we will agree moderators, and we will stifle debate immediately.
So I think stick with no moderation, I would even go so far as no ignore function!  Plenty of people have said 'I am always interested in how others I disagree with have come to their views', then stick those very people with differing views on to ignore, thus meaning they never get to find out how those views were formed and never have to be properly challenged.  Strange behaviour.
		
		
	 
I think being civil is a reasonable ask.
Of course, one person's civil is another person's coarse.
I didn't say anything about moderation.
You can agree a code of conduct without it being politically biased though.
Through consensus.
The basics such as no racism, sexism, homophobia etc, not misquoting, not misrepresenting, nor harassment.
No abusive language .
Sure there's more, those would just be basics.
It's perfectly possible to ignore people without having an ignore function as such, anyway.
No one is 'owed' a response.
Especially if previous experience has shown that interactions are fairly fruitless .