1	{ "payload": "p1\u4e16", "kind": "MSG_IN", "at_ms": 1, "future": true }
5000	{ "payload": "p2\u4e16", "kind": "MSG_IN", "at_ms": 1, "future": true }
5001	{"at_ms":1700000000000,"kind":"USER_INPUT","payload":"new"}