Status: IN
`can_enter()` returns `True` only when the node's request is at the queue head (lowest `(timestamp, node_id)`) AND acknowledgments have been received from every other node in the system.
Source: entries/2026/05/29/lamport-clocks-lamport.md
others = set(self._nodes.keys()) - {node.node_id}
return others.issubset(self._acks.get(node.node_id, set()))