phase A: ai:alice writes handoff to ai:bob (uuid=h-7246604c1380485191ba50cbb1277871)
settle 8s for quorum fanout
phase B: ai:bob reads handoff on node-2
  ai:bob sees 1 handoff memories from ai:alice
phase C: ai:bob writes acknowledgement (uuid=a-9058de59de0a4516b02362546e4bf6ed)
settle 8s for reverse-direction fanout
phase D: ai:alice reads ack on node-1
  ai:alice sees 1 ack memories from ai:bob