What
The sandbox is a protected space that limits what commands Claude runs can touch. On Windows, a command has a maximum length. Folders added after the sandbox started, from worktrees (separate working copies of a project) or from /add-dir, add file rules to every command and can push it over that limit.
Before, this produced only a general "too long" message. Now Claude Code says "Command is too long to run in the Windows sandbox." and suggests:
- writing the command to a file and running that
- running fewer subagents (helper agents) at once
- restarting
Why
Windows sandbox users with many worktrees or added folders now get an explanation for a failure that was confusing before.
Names in the bundle/add-dir