You'll notice
Removing a worktree mid-session now tells you its commits are still kept on the server
What
A worktree is a separate working copy of a git repository that Claude Code can use during a session. If you remove a worktree partway through a session and it had commits made in it, the message you now see includes a note that those commits remain stored server-side, along with a shortened id of the last commit (the 'head changeset').
Why
This reassures you that deleting the worktree doesn't lose the work done in it, since the commits are still retained on the server rather than only existing in the now-removed local copy.