No one single event. But I think it’s good to be reminded every now and again. There was just one criteria I had for having a project fall under the stan-dev umbrella (and I think most of the devs at the time agreed): development discussion must be open. It doesn’t have to be here, but it does have to be open. If it’s closed, that’s cool; I’d just ask it be moved.
(Sorry, I wasn’t trying to call you out because I thought there was anything. It was more curiosity and a reminder if there was anything.)
That said, I’ve seen at least a few comments on development for Stan that aren’t on these forums when they should be (if they’re done over emails). My guess is that the participants just didn’t know that it’s important to have things in the open. The benefits and drawbacks for open communication is asymmetric for the individual and the community.
From the community’s point of view, if there was a lot of development discussion in private, that limits the ability of potential contributors or collaborators to get involved. Moreover, it can cause some distrust. There’s now a subgroup making decisions according to what they think is right without the community having a chance to help, observe, comment, object, support, or anything else. And then there’s the question of what other development-related decisions are being made without the community involved. It shifts from having an open, welcoming community to a community where there’s an insider group that’s above accountability and where people outside of that group can’t affect change. And yes, I realize we’re very far from there. I just want to proactively keep the community away from there.
(And yes, there are times when it’s appropriate to have discussion via private emails. I’m not suggesting all communication be open. And I’m not discouraging meeting up in person to discuss things.)