Change ClusterEntry from sealed record to sealed class so TryUpdate
uses reference equality for the CAS comparison. Prune now uses a
read-compute-TryUpdate retry loop that restarts when a concurrent
Install updates the entry between the read and the write, preventing
a race that could silently drop the just-installed newest generation.
Two regression tests added to PermissionTrieCacheTests.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty
debe163f4d