What
A git worktree is an extra working copy of a repository that Claude Code can create to work in. When Claude Code cannot work out which commit a new worktree should start from, it now shows a detailed error with the cause and advice. For example, it may suggest setting worktree.baseRef to "head" in Claude Code settings, so worktrees start from your current commit.
Why
If worktree creation fails, the message now tells you what went wrong and what setting to change.
Names in the bundleworktree.baseRef
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Confirmed since
Anthropic's documentation has since written up worktree.baseRef, on What's new.
Also this week: **`worktree.baseRef`** chooses whether new worktrees branch from the remote default or local `HEAD`; **auto mode hard deny rules** block actions unconditionally regardless of allow exceptions; and **hooks see the active eff…whats-new/index see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up worktree.baseRef, on What's new.