Right now, when force pushing, we preserve event logs for every server mutation, but the review themselves are lost.

We do see this as a problem and are thinking about ways to address it. We do support the idea of a patchset (that's what the patch request managed). Right now we only support a single patchset for a patch request, but we are leaning toward introducing patch revisions where both contrib and owner submit entire versions of the patchset. This could provide better tracability since reviews would be in a separate patchset "channel" and not lost to force pushing.

We also plan on supporting a patch request "cover letter" which includes all the events and comments during review. This cover letter is just an empty patch which could be `git am --empty=keep` or `git am --empty=drop` depending on preference.