CheckpointTuple(
    config={'configurable': {'thread_id': '1', 'checkpoint_id': '1f029ca3-...'}},
    checkpoint={
        'id': '1f029ca3-...',
        'ts': '2026-05-05T16:01:24+00:00',
        'channel_values': {                      # ← 아까 그 state 가 통째로
            'messages': [HumanMessage(...), AIMessage(...)],
            'step': 3,
        },
    },
    metadata={'source': 'loop', 'step': 4, 'thread_id': '1'},
    parent_config={'configurable': {'checkpoint_id': '1f029ca3-1790-...'}},
)