Function diff_against_latest 

pub fn diff_against_latest(
    paths: &Paths,
    probes: &[&dyn PlatformProbe],
) -> Result<Option<DiffReport>>

Compute the diff between the current inventory and the latest snapshot without persisting a new snapshot.

Use this when you want a read-only “what changed since the last scan::run” view — repeated calls compare against the same baseline. Returns Ok(None) when no previous snapshot exists yet.

paths.user_home drives inventory target roots; paths.home drives snapshot lookup. No I/O is performed under paths.home/snapshots/.

Errors

Returns crate::Error::Io on inventory walk failure or crate::Error::Scan on snapshot parse failure.