[Release] anthropics/claude-code v2.1.133: v2.1.133

Claude Code v2.1.133 introduces enhanced worktree configuration with `worktree.baseRef` settings, improved sandbox path management for Linux/WSL, and critical fixes for parallel sessions, proxy handling, and effort level synchronization. The release addresses memory efficiency, credential management, and cross-session consistency issues while improving focus mode behavior and MCP OAuth flow support.

Key Points

• •Added `worktree.baseRef` setting to control whether worktrees branch from `origin/<default>` (fresh) or local HEAD, with default changed to 'fresh' — set to 'head' to preserve unpushed commits
• •New `sandbox.bwrapPath` and `sandbox.socatPath` managed settings allow custom bubblewrap and socat binary locations on Linux/WSL
• •Hooks now receive active effort level via `effort.level` JSON field and `$CLAUDE_EFFORT` environment variable for dynamic tool behavior
• •Fixed critical 401 race condition in parallel sessions caused by refresh-token conflicts wiping shared credentials
• •Fixed proxy configuration (`HTTP(S)_PROXY`, `NO_PROXY`, mTLS) not being respected for full MCP OAuth flow including discovery and token operations
• •Resolved `/effort` command unexpectedly changing effort levels across concurrent sessions and IDE effort changes being silently dropped
• •Fixed Read/Write/Edit permissions on mapped network drives passed via `--add-dir` and SDK `additionalDirectories`
• •Improved memory usage by releasing warm-spare background workers under memory pressure
• •Fixed Remote Control stop/interrupt from claude.ai not fully canceling CLI sessions, leaving queued messages stuck
• •Added `parentSettingsBehavior` admin-tier key ('first-wins' | 'merge') for SDK managedSettings policy control

Workflow Diagram

Concepts