[BUG] Worktree session gets passed incorrect branch name

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When running claude --worktree <name>, Claude gets told the current branch is the branch from _before_ the worktree was created.

The branch name seems to be injected into the system prompt as part of the startup context.

<img width="625" height="251" alt="Image" src="https://github.com/user-attachments/assets/de991dda-2841-4f06-8a90-3cad32d5567f" />

What Should Happen?

Run claude --worktree test and Claude knows it's on worktree-test.

Error Messages/Logs

Steps to Reproduce

1. Run claude --worktree test
2. Ask Claude "what branch are we on?"

It will give you the wrong answer.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.68

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)