We found the basic models in Slack, Teams and Zulip too rigid. In all such clones of the Slack design, the members of channels (and threads) are static. You are

We found the basic models in Slack, Teams and Zulip too rigid. In all such clones of the Slack design, the members of channels (and threads) are static. You are either a participant in the entire channel or you arent. But it doesnt work like that in the real world. For starters, a thread is a personal idea. (I think this is what you mean by opt-in). My idea of a thread is probably not your idea of a thread. So the concept of shared thread (channel) is hard to fathom. Second, my thread is made of activities I need to complete for the task at hand. In the process, I will interact with as many people or as few as I see fit, all in the pursuit of my goal. Not all the people I interact with (thread participants) are necessarily members of my team. This is where the rigidity is a real problem with the aforementioned products. I cannot know all the participants at the time of channel creation. And once involve a non-team-member user in the thread, they become unwitting recipients of noise, and they cant do a damn thing about it. There's gotta be a better way.