The diagnostics are collected and available still, since that might become a settings/UI toggle later. Also, buffer diagnostics are still updated for gitignored files.
Zed Server
This crate is what we run at https://collab.zed.dev.
It contains our back-end logic for collaboration, to which we connect from the Zed client via a websocket after authenticating via https://zed.dev, which is a separate repo running on Vercel.