Screens update in place

Give a row a name and a later reply changes just that row. A timer, a score or a status line updates where it sits instead of arriving again, and a reply that only changes the screen doesn't buzz your phone.

say "Leg day, live. A later reply changes one row by its name."
timeline "Leg day"
done@warmup "Warm-up" sub="10 min"
now@squat "Back squat" sub="set 2 of 4"
next@lunge "Walking lunges"