sequence property
Monotonic within one guest, and the whole reason a console can be both pulled and pushed without showing anything twice.
A reader takes the buffer when it opens and subscribes to the pushes at the same time; the two overlap by however long the round trip took. With this, the overlap is dropped by number. Without it, the reader would have to match on text and time and would still be wrong about a demo printing the same word twice in a frame.
Implementation
final int sequence;