[BUG] Worktree sets branch upstream to origin/dev, causing VS Code push to go to dev instead of feature branch

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 Claude Code creates a worktree, it branches from origin/dev (a remote-tracking branch) rather than the local dev branch. With the default branch.autoSetupMerge=true, this causes git to automatically set branch.<name>.merge=refs/heads/dev - making the feature branch track origin/dev as its upstream.

This is catastrophic for users with push.autoSetupRemote=true, because:

1. Normally: user creates git checkout -b ASP-XXXX dev (from local dev) -> no upstream is set -> push.autoSetupRemote kicks in on first push -> creates origin/ASP-XXXX correctly
2. With worktree: Claude Code branches from origin/dev (remote-tracking) -> upstream is set to origin/dev -> push.autoSetupRemote does NOT kick in (upstream already exists) -> push goes directly to dev

When the user clicks "Push" in VS Code, VS Code reads the tracking config and runs git push origin <branch>:dev, pushing directly to the main development branch instead of the feature branch.

What Should Happen?

The worktree branch should either:

• Be created from the local branch (not the remote-tracking branch), so that branch.autoSetupMerge=true does not set upstream tracking
• Or explicitly clear/unset the upstream tracking after branch creation (git branch --unset-upstream)
• Or set the upstream to match the branch name (origin/<branch-name>)

Error Messages/Logs

Git config after worktree creation:

branch.ASP-1305.remote=origin
branch.ASP-1305.merge=refs/heads/dev       # <-- should NOT be set, or should be refs/heads/ASP-1305

VS Code push log showing the wrong target:

git push origin worktree-ASP-1305:dev
git push origin ASP-1305:dev

Both pushes went to dev, bypassing branch protection (user had admin bypass).

Steps to Reproduce

1. Have push.autoSetupRemote=true in git config (common modern git setup)
2. Be on a feature branch (e.g., ASP-1305) created from local dev
3. Use Claude Code worktree feature (EnterWorktree)
4. After exiting the worktree, check git config branch.<name>.merge - it will show refs/heads/dev
5. Click "Push" in VS Code -> commits go directly to dev

Impact

Commits were pushed directly to the protected dev branch unintentionally. This bypassed the PR workflow and branch protection rules.

Related Issues

• #33596 - opposite problem: worktree branches with no upstream (fails to push)
• #30070 - worktree using wrong remote in multi-remote setups

Claude Model

Opus

Is this a regression?

Not sure

Claude Code Version

Latest

Platform

Anthropic API

Operating System

Windows 11