Claude Code version 2.1.221 introduces a new Focus view that hides tool activity behind an expandable summary, adds mask mode for sandbox credential files on Linux and WSL, and resolves critical security issues in the Bash tool.
- Added Focus view toggle to hide tool activity with a live running-tool indicator.
- Introduced `mode: "mask"` for sandbox credentials, allowing sandboxed commands to read sentinel copies while the proxy substitutes real values.
- Fixed a Bash tool permission-check bypass where zsh could execute hidden commands in regex conditionals.
- Fixed PowerShell permission checks mishandling paths with quote characters on Windows.
- Improved auto mode by making permission checks for parallel tool calls cache-efficient.
- Reduced prompt-cache costs for auto-mode permission checks by reusing the cached conversation prefix.
The update enhances security by patching permission bypasses and improves usability through new interface controls and performance optimizations.