alice writes M1 content=v0-ab328b33354a4cfd8fbfbb44ec5be463 on node-1
  M1 id=96158b85-97d0-436e-bba8-981f2f9094df
settle 5s for initial replication
alice + bob issue concurrent PUTs (vA=va-83073cf2d9414736a06101e4d9abb290 from alice, vB=vb-5641113c68a4460e91c0e234ac1c9517 from bob)
  concurrent PUT results: [(0, {'body': {'access_count': 0, 'confidence': 1.0, 'content': 'va-83073cf2d9414736a06101e4d9abb290', 'created_at': '2026-04-23T14:04:55.723279205+00:00', 'expires_at': '2026-04-30T14:04:55.723279205+00:00', 'id': '96158b85-97d0-436e-bba8-981f2f9094df', 'metadata': {'agent_id': 'ai:alice', 'scenario': '13'}, 'namespace': 'scenario13-contention', 'priority': 5, 'source': 'api', 'tags': [], 'tier': 'mid', 'title': 'm1', 'updated_at': '2026-04-23T14:05:01.973241150+00:00'}, 'http_code': 200}), (0, {'body': {'access_count': 0, 'confidence': 1.0, 'content': 'vb-5641113c68a4460e91c0e234ac1c9517', 'created_at': '2026-04-23T14:04:55.723279205+00:00', 'expires_at': '2026-04-30T14:04:55.723279205+00:00', 'id': '96158b85-97d0-436e-bba8-981f2f9094df', 'metadata': {'agent_id': 'ai:alice', 'scenario': '13'}, 'namespace': 'scenario13-contention', 'priority': 5, 'source': 'api', 'tags': [], 'tier': 'mid', 'title': 'm1', 'updated_at': '2026-04-23T14:05:03.112996307+00:00'}, 'http_code': 200})]
settle 10s for quorum convergence
  node-1 sees content=vb-5641113c68a4460e91c0e234ac1c9517
  node-2 sees content=vb-5641113c68a4460e91c0e234ac1c9517
  node-3 sees content=vb-5641113c68a4460e91c0e234ac1c9517
  node-4 sees content=vb-5641113c68a4460e91c0e234ac1c9517