Slack is good, but threads get buried and pinning stuff gets cumbersome. so, I propose the following workflow when discussing stuff:

• We start a discussion on Slack. if it's not leading anywhere meaningful, we stop and we call it a day. if it's worth archiving it:
• We move the description of the problem to be discussed to a Github Issue, along with some of the pre-discussions that we had on Slack
• We continue on point-discussions

When an idea reaches maturity, we can then escalate the discussed matters into a proper PIP.