alice writes M1 content=v0-9f4df7bcfab04f30b8eab4319460f765 on node-1
  M1 id=aaf74b94-c6c5-4f67-890f-445c214b39f3
settle 5s for initial replication
alice + bob issue concurrent PUTs (vA=va-8db5573a975343b8b746416952c78fd4 from alice, vB=vb-84e72076f77a4f58997583b836703157 from bob)
  concurrent PUT results: [(0, {'body': {'access_count': 0, 'confidence': 1.0, 'content': 'va-8db5573a975343b8b746416952c78fd4', 'created_at': '2026-04-23T17:13:22.819028080+00:00', 'expires_at': '2026-04-30T17:13:22.819028080+00:00', 'id': 'aaf74b94-c6c5-4f67-890f-445c214b39f3', 'metadata': {'agent_id': 'ai:alice', 'scenario': '13'}, 'namespace': 'scenario13-contention', 'priority': 5, 'source': 'api', 'tags': [], 'tier': 'mid', 'title': 'm1', 'updated_at': '2026-04-23T17:13:29.025273253+00:00'}, 'http_code': 200}), (0, {'body': {'access_count': 0, 'confidence': 1.0, 'content': 'vb-84e72076f77a4f58997583b836703157', 'created_at': '2026-04-23T17:13:22.819028080+00:00', 'expires_at': '2026-04-30T17:13:22.819028080+00:00', 'id': 'aaf74b94-c6c5-4f67-890f-445c214b39f3', 'metadata': {'agent_id': 'ai:alice', 'scenario': '13'}, 'namespace': 'scenario13-contention', 'priority': 5, 'source': 'api', 'tags': [], 'tier': 'mid', 'title': 'm1', 'updated_at': '2026-04-23T17:13:28.992667618+00:00'}, 'http_code': 200})]
settle 10s for quorum convergence
  node-1 sees content=va-8db5573a975343b8b746416952c78fd4
  node-2 sees content=va-8db5573a975343b8b746416952c78fd4
  node-3 sees content=va-8db5573a975343b8b746416952c78fd4
  node-4 sees content=va-8db5573a975343b8b746416952c78fd4