mkwt

Create a new git worktree and branch.

Usage

/mkwt <name> — Create a worktree with a new branch <name> from the repo's default branch (e.g. main, dev).

The <name> argument is required. If not provided, ask the user for a name.

Workflow

1. Validate the name argument is provided.

2. Detect the worktree base directory by inspecting existing worktrees:

   git worktree list
   

   • Look at paths of worktrees OTHER than the main worktree (the first entry, which is the repo itself).
   • If secondary worktrees exist, derive the base directory from their common parent. For example, if existing worktrees are at /Users/foo/worktrees/meadow/branch_a and /Users/foo/worktrees/meadow/branch_b, the base is /Users/foo/worktrees/meadow/.
   • If NO secondary worktrees exist (only the main repo), ask the user where to create the worktree.

3. Check the branch doesn't already exist:

   result=$(git branch --list <name>); if [ -n "$result" ]; then echo "EXISTS"; else echo "FREE"; fi
   

   Important: git branch --list always exits 0, even with no matches. You must check the output (non-empty = exists), not the exit code. If it exists, tell the user and stop.

4. Check the worktree path doesn't already exist:

   ls <BASE_DIR>/<name>
   

   If it exists, tell the user and stop.

5. Confirm with the user before creating:

   Create worktree <name> at <BASE_DIR>/<name> (new branch from <DEFAULT_BRANCH>)?

6. Create the worktree:

   git worktree add <BASE_DIR>/<name> -b <name>
   

   Important: This command writes outside the project directory, so it requires dangerouslyDisableSandbox: true. If it fails due to sandbox restrictions, the branch may still be created (partial failure). Delete the branch with git branch -d <name> before retrying.

7. Print the result:

   Created worktree <name> at <BASE_DIR>/<name>.