Function load 

pub fn load(root: &Path) -> ImpactStore

Load the store. A missing file is the normal “not enabled yet” case and returns a default silently. A present-but-unparsable file is surfaced with a one-line warning (rather than silently disabling tracking) and then degrades to a default; the corrupt file is left on disk untouched, and because record_audit_run no-ops on a disabled store it is never overwritten, so re-running fallow impact enable is a deliberate reset.