Claude Code v2.1.133: worktree.baseRef revert, sandbox paths, proxy fix for MCP OAuth

Anthropic released Claude Code v2.1.133 with several configuration additions and critical fixes. The notable update is the worktree.baseRef setting, which controls whether --worktree, EnterWorktree, and agent-isolation worktrees branch from origin/<default> or local HEAD. The default is fresh, reverting EnterWorktree to branch from origin/<default> — this changes the behavior from v2.1.128 which used local HEAD. To keep unpushed commits in new worktrees, set worktree.baseRef: "head".

New Settings & Features

• worktree.baseRef (fresh | head): Choose worktree base branch. Default fresh uses origin/<default>; set to head to inherit local HEAD.
• sandbox.bwrapPath and sandbox.socatPath (Linux/WSL): Specify custom bubblewrap and socat binary paths.
• parentSettingsBehavior (admin-tier key, first-wins | merge): Allows admins to opt SDK managedSettings into policy merge.
• Hooks now receive effort level: Via effort.level JSON input and $CLAUDE_EFFORT environment variable. Bash tool commands can read $CLAUDE_EFFORT.

Improvements & Fixes

• Focus mode: Behavior improved.
• Memory usage: Warm-spare background workers released under memory pressure.
• Parallel sessions 401: Fixed dead-end after refresh-token race wiping credentials.
• Edit/Write allow rules: Fixed scope matching on drive root (C:\) or POSIX / incorrectly always prompting.
• ECOMPROMISED lock error: Fixed unhandled rejection from clock skew or slow disk corrupting session-log file locks.
• Spurious compaction error: Pressing Esc during compaction no longer shows "Error compacting conversation".
• HTTP(S)_PROXY / NO_PROXY / mTLS: Now respected for the full MCP OAuth flow (discovery, dynamic client registration, token exchange, token refresh).
• Mapped network drives: Read/Write/Edit allowed when passed via --add-dir or SDK additionalDirectories.
• Remote Control stop: From claude.ai now fully cancels CLI session like local Esc, preventing stuck queued messages.
• Effort cross-session leak: /effort in one session no longer changes others; IDE effort changes no longer silently dropped.
• Subagent skill discovery: Fixed subagents not finding project, user, or plugin skills via the Skill tool.

CLI & VSCode

• claude --help now lists --remote-control alongside --remote-control-session-name-prefix.
• [VSCode] Fixed claudeCode.claudeProcessWrapper failing with "Unsupported platform" when extension build lacks bundled Claude binary.