GitHub definitely does support (1)! You just comment and click “add to review” as you go and then submit them all together at the end. It’s been the default for

GitHub definitely does support (1)! You just comment and click “add to review” as you go and then submit them all together at the end. It’s been the default for a while now. For (2) you definitely want Gerrit. For major improvements on (1), (3), and (4) you might like https://codeapprove.com https://codeapprove.com which sits on top of GitHub and attempts to solve your pain points. Obviously I am biased!