Function trace_route 

pub fn trace_route(
    db_path: impl AsRef<Path>,
    tenant: &str,
    trace_id: &str,
) -> Result<Option<Option<u32>>, StoreError>

The route index recorded on trace_id, scoped to tenant.

Ok(None) means the trace is not visible to this tenant (or does not exist) — the same ownership check trace_exists makes, so this cannot be used to probe another tenant’s traces. Ok(Some(None)) means the trace exists but predates route recording.

Errors

On a store read failure.