pub fn reverse_reads(op: &Op) -> Vec<Reg> ⓘExpand description
The registers a REVERSE step reads from the live machine (not from the tape) when undoing op —
so their values must be intact at reverse time. Journaled overwrites restore their destination
straight from the tape and read NOTHING live, so they contribute none; only the Bijection ops
(which recompute in place) and the collection/CRDT reverses (which read the live handle) do.
Eliding a journal entry for a register in this set could corrupt a later reverse-read, so the
pebbler treats membership here as “must keep”. Keep in lockstep with the reverse executor.