Function find_event_across_segments 

pub fn find_event_across_segments(
    active: &Path,
    reads_archives: bool,
    id: &str,
) -> Result<SegmentLookup>

Find one event by id across the active file and every retained archive, newest source first. Owns segment enumeration for the same reason as query_log_page: the caller never holds a list that can go stale.

A segment that cannot be read is skipped rather than failing the lookup, so one unreadable file does not hide an event another segment still has. When that happens and nothing matched, SegmentLookup::incomplete says the miss is not authoritative.