Using Git Worktrees

Using Git Worktrees

Overview

Ensure work happens in an isolated workspace. Prefer your platform's native worktree tools. Fall back to manual git worktrees only when no native tool is available. If git is unavailable or the project is not a git repository, create an isolated filesystem copy instead.

Core principle: Detect existing isolation first. Then use native tools. Then fall back to git. Then use a non-git copy fallback. Never fight the harness.

Announce at start: "I'm using the using-git-worktrees skill to set up an isolated workspace."

Step 0: Detect Git Availability And Existing Isolation

Before creating anything, check whether git can be used here.

command -v git >/dev/null 2>&1
git rev-parse --is-inside-work-tree >/dev/null 2>&1

If git is not installed: Skip git-specific detection and go to Step 2 (Non-Git Copy Fallback).

If the current directory is not inside a git work tree: Skip git-specific detection and go to Step 2 (Non-Git Copy Fallback).

If git is available and the project is a git repository, check if you are already in an isolated workspace.

GIT_DIR=$(cd "$(git rev-parse --git-dir)" 2>/dev/null && pwd -P)
GIT_COMMON=$(cd "$(git rev-parse --git-common-dir)" 2>/dev/null && pwd -P)
BRANCH=$(git branch --show-current)

Submodule guard: GIT_DIR != GIT_COMMON is also true inside git submodules. Before concluding "already in a worktree," verify you are not in a submodule:

# If this returns a path, you're in a submodule, not a worktree - treat as normal repo
git rev-parse --show-superproject-working-tree 2>/dev/null

If GIT_DIR != GIT_COMMON (and not a submodule): You are already in a linked worktree. Skip to Step 3 (Project Setup). Do NOT create another worktree.

Report with branch state:

• On a branch: "Already in isolated workspace at <path> on branch <name>."
• Detached HEAD: "Already in isolated workspace at <path> (detached HEAD, externally managed). Branch creation needed at finish time."

If GIT_DIR == GIT_COMMON (or in a submodule): You are in a normal repo checkout.

Has the user already indicated their worktree preference in your instructions? If not, ask for consent before creating a worktree or copy:

"Would you like me to set up an isolated workspace? It protects your current directory from changes."

Honor any existing declared preference without asking. If the user declines consent, work in place and skip to Step 3.

Step 1: Create Isolated Workspace

You have two git-aware mechanisms. Try them in this order.

1a. Native Worktree Tools (preferred)

The user has asked for an isolated workspace (Step 0 consent). Do you already have a way to create a worktree? It might be a tool with a name like EnterWorktree, WorktreeCreate, a /worktree command, or a --worktree flag. If you do, use it and skip to Step 3.

Native tools handle directory placement, branch creation, and cleanup automatically. Using git worktree add when you have a native tool creates phantom state your harness can't see or manage.

Only proceed to Step 1b if you have no native worktree tool available and git is usable in the project.

1b. Git Worktree Fallback

Only use this if Step 1a does not apply - you have no native worktree tool available, git is installed, and the current project is a git repository. Create a worktree manually using git.

Directory Selection

Follow this priority order. Explicit user preference always beats observed filesystem state.

1. Check your instructions for a declared worktree directory preference. If the user has already specified one, use it without asking.

2. Check for an existing project-local worktree directory:

   ls -d .worktrees 2>/dev/null     # Preferred (hidden)
   ls -d worktrees 2>/dev/null      # Alternative

   If found, use it. If both exist, .worktrees wins.

3. Check for an existing global directory:

   project=$(basename "$(git rev-parse --show-toplevel)")
   ls -d ~/.config/superpowers/worktrees/$project 2>/dev/null

   If found, use it (backward compatibility with legacy global path).

4. If there is no other guidance available, default to .worktrees/ at the project root.

Safety Verification (project-local directories only)

MUST verify directory is ignored before creating worktree:

git check-ignore -q .worktrees 2>/dev/null || git check-ignore -q worktrees 2>/dev/null

If NOT ignored: Add to .gitignore, commit the change, then proceed.

Why critical: Prevents accidentally committing worktree contents to repository.

Global directories (~/.config/superpowers/worktrees/) need no verification.

Create the Worktree

project=$(basename "$(git rev-parse --show-toplevel)")

# Determine path based on chosen location
# For project-local: path="$LOCATION/$BRANCH_NAME"
# For global: path="~/.config/superpowers/worktrees/$project/$BRANCH_NAME"

git worktree add "$path" -b "$BRANCH_NAME"
cd "$path"

Sandbox fallback: If git worktree add fails with a permission error (sandbox denial), tell the user the sandbox blocked worktree creation and you're working in the current directory instead. Then run setup and baseline tests in place.

Other git worktree failure: If git worktree add fails because git metadata is broken, the repository has unsupported layout, or worktree commands are unavailable, go to Step 2 (Non-Git Copy Fallback).

Step 2: Non-Git Copy Fallback

Use this when git is not installed, the current directory is not a git repository, or git worktree creation is impossible for a non-permission reason.

Goal: Preserve the user's current workspace by copying source files to a sibling or project-local isolated directory, then work from the copy.

Directory Selection

Follow this priority order. Explicit user preference always beats observed filesystem state.

1. Check your instructions for a declared isolated workspace directory preference. If the user has already specified one, use it without asking.

2. Check for an existing project-local isolation directory:

   ls -d .worktrees 2>/dev/null
   ls -d worktrees 2>/dev/null

   If found, use it. If both exist, .worktrees wins.

3. If the project has a parent directory you can write to, default to a sibling directory named <project-name>-workspace/<task-name-or-timestamp>.

4. If a sibling directory is not possible, default to .worktrees/<task-name-or-timestamp> inside the current project.