What's new in Claude Code v2.1.133

Five quiet but consequential changes for advanced users: subagents finally inherit project, user, and plugin skill discovery; hooks see the active effort level via JSON input and a $CLAUDE_EFFORT env var; new worktree.baseRef setting picks whether worktrees branch from origin/ or local HEAD; admins get sandbox.bwrapPath and sandbox.socatPath for non-standard Linux/WSL deployments; and SDK hosts get parentSettingsBehavior for managed-settings merge control.

Subagents now discover project, user, and plugin skills

Why: Subagents were skill-blind — they only saw built-in tools, not the skills the parent session had access to.

What: Subagents now inherit skill discovery from project, user, and plugin sources.

How: No action — subagents pick up skills automatically.

Hooks now receive effort.level and $CLAUDE_EFFORT

Why: Hooks couldn't tell which effort level a session was running at, so they couldn't tailor behavior to high/medium/low effort.

What: Hook JSON input now includes effort.level, and $CLAUDE_EFFORT is exposed to hook subprocesses.

How: Read input.effort.level in hook JSON or $CLAUDE_EFFORT in hook scripts.

worktree.baseRef setting

Why: Worktrees default to branching from origin/, but team workflows that want HEAD-based branches had no opt-in.

What: New worktree.baseRef setting picks whether new worktrees branch from origin/ or local HEAD.

How: Set "worktree": { "baseRef": "head" } in .claude/settings.json.

sandbox.bwrapPath and sandbox.socatPath managed settings

Why: Linux/WSL sandboxing relies on bwrap and socat, but their paths can vary across distributions and managed deployments couldn't override.

What: Two new managed settings let admins point Claude Code at custom bwrap and socat binaries.

How: Set "sandbox": { "bwrapPath": "...", "socatPath": "..." } in managed settings.

parentSettingsBehavior — SDK managed-settings merge policy

Why: SDK hosts using managedSettings had no way to control how parent settings merged with child overrides.

What: New admin-tier parentSettingsBehavior key configures the merge policy for managed-settings inheritance.

How: Set "parentSettingsBehavior" in the SDK host's managed settings.

Hosts: Alex Chen & Sarah Kim · Generated from the official Claude Code CHANGELOG.

Full changelog: github.com/anthropics/claude-code/CHANGELOG.md

Claude Code docs: docs.claude.com/en/docs/claude-code

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