How about a new request type that only vaults can make (ie not clients): starting at <xorname> return the first N chunk names you have stored
This would allow vaults to prefill their cache (by requesting chunks by name like a normal client would) and also allow some degree of auditing since multiple vaults would overlap the name range and should all respond the same way.
It’d be cool to be able to do audits without impacting the workload of elders.