The combined-mask cache was capped only at 64 entries, so large feathered masks could retain a
lot of memory, and Edit > Purge > All left them allocated. The cache is now also bounded to
512 MiB of accounted pixel bytes (result plus the pinned input), Purge All clears it and reports
its bytes, and a purge generation stops a build that started earlier from refilling the cache.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
