It’s worth noting that the Zulip team are also interested in better supporting open source projects like Rust. Just yesterday, there was a small discussion about this discussion in the Zulip organisation’s chat where Tim Abbott, the lead developer of Zulip said:
I should mention that in general we’re quite responsive to the needs of open source projects; if folks involved with Rust want to talk to some of the open source projects that have adopted Zulip and been really happy with it, we can set that up.
This would work for things like
#design-impl-Trait but would struggle to be as flexible as Zulip’s model when it comes to a channel per issue (which is effectively how the NLL working group is using Zulip’s threads currently).