You'll notice
A lingering artifact-watch background monitor no longer blocks a session from going idle
What
Claude Code decides whether a session has "settled" enough to be considered idle or eligible for retirement by counting outstanding in-flight tasks. That count now subtracts any monitors marked as drainable, and when such monitors exist, an artifact_watch background monitor (which watches an artifact for changes) is no longer counted among the things blocking idle or retirement.
Why
Previously a session could be kept from going idle or being retired just because an artifact-watch monitor was still running in the background. Now that monitor no longer holds a session open unnecessarily.