The volume server names the directory index in every
VolumeShortInformationMessage, but NewVolumeInfoFromShort dropped it, so
volumes registered through the incremental new-volume path showed
disk_id 0 at the master until a full report -- misreporting multi-dir
servers in volume.list and the per-physical-disk topology views.
Claude-Session: https://claude.ai/code/session_01QdTEEPbg4MtcoEGwqbgtZC