Function read_recorded_epoch 

pub fn read_recorded_epoch(path: &Path) -> Result<Option<DateTime<Utc>>, String>

Read only the virtual-time epoch stored in a preemption record file.

Unlike PreemptionReader::new, this reports an unreadable or malformed file as an error instead of panicking, because the CLI consults it before any guest starts. Ok(None) means the record predates stored epochs.