The spec is https://review.opendev.org/#/c/726070/ I took the action item at today's virtual mid-cycle meeting to summarize the discussion on the review so that the spec can be revised. While doing that, I looked through the code carefully, and I think that the spec is actually on the right track, though there seem to be several bugs associated with this issue. In any case, I just left an enormous comment on the review. I need other reviewers to read through and comment/respond so that haixin and zhangbailin can get some consensus on how to revise the spec. thanks, brian