[Release] anthropics/claude-code v2.1.216: v2.1.216

Claude Code v2.1.216 is a maintenance release focused on stability and performance improvements. Key fixes address quadratic slowdown in long sessions, OAuth token handling, file isolation settings, and numerous UI/terminal rendering issues. The release also improves command validation, workflow handling, and background session management across multiple platforms including VSCode and web clients.

Key Points

• •Added `sandbox.filesystem.disabled` setting to disable filesystem isolation while maintaining network egress control
• •Fixed critical performance regression where message normalization cost grew quadratically with session turns, causing multi-second stalls
• •Resolved OAuth token expiration issues preventing command execution with HTTP 401 classifier errors
• •Fixed AskUserQuestion behavior to use neutral wording for free-text answers instead of forcing continuation
• •Corrected web client session idle behavior that re-asked questions and dropped user answers after inactivity
• •Restored agent prompt and tool restrictions in resumed background sessions (previously reverted to defaults)
• •Fixed worktree isolation issues where subagents could redirect git operations to shared checkouts
• •Improved permission checking for Bash compound statements with redirects and PowerShell Unicode character handling
• •Enhanced `/fork`, `/ultrareview`, and `/code-review` command feedback with clearer confirmation messages and error details
• •Fixed symlink following vulnerabilities in workflow saves and scheduled-task writes that could redirect outside projects

Workflow Diagram

Concepts