Function finding_id 

pub fn finding_id(
    group: &CloneGroupFingerprint,
    host: Option<&UnitFingerprint>,
    rank_in_host: u32,
) -> FindingId

Identify one occurrence of a group’s content.

Content-identical occurrences share their content fingerprint, so a finding is discriminated by its host unit’s (raw) fingerprint plus its occurrence rank within that host — content-relative inputs, not source positions. An occurrence outside any unit uses an absent-host marker; two such occurrences are then told apart by rank alone, which is the weakest (but position-free) discriminator available at this layer.