A volume is read-only while its disk is low on space, but it still
applies deletes; only noWriteOrDelete refuses them. The heartbeat set
readOnlyCanDelete from the operator mark alone, so the master listed a
low-disk replica as refusing deletes and the replica count check
rejected every delete on its volumes, on the healthy replicas too.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>