pub const MAX_FRESH: usize = 1_024;Expand description
Sessions not in the table yet whose deliveries a summary keeps (Summary::fresh). Guard: bounds the
cache against sessions shown lessons (an early delivery at a prompt) that never reach a graded check,
which no other bound counts; far more than run at once, about 0.1 MB. Past it the oldest quarter go,
and one of them graded after all counts its applies of lessons it had as a session without them.