superpowers/skills/using-git-worktrees/SKILL.md

name, description

name	description
using-git-worktrees	Use when starting feature work that needs isolation from current workspace or before executing implementation plans - detects environment, offers worktree isolation when appropriate

Using Git Worktrees

Overview

Detect the workspace environment. Work in place by default. Offer worktree isolation when the user would benefit, but only create one when they explicitly ask.

Core principle: Detect first. Default to working in place. Create worktrees only on explicit user request. Never fight the harness.

Announce at start: "I'm using the using-git-worktrees skill to check the workspace."

Step 1: Detect Existing Isolation

Before anything else, 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 4 (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. Proceed to Step 2.

Step 2: Offer Workspace Options

The default path is to work in place on your current branch. Do NOT create a worktree unless the user explicitly asks for one.

# Report current state to the user
echo "Current branch: $BRANCH"
echo "Repository: $(basename "$(git rev-parse --show-toplevel)")"

Check the user's most recent message first. If they already asked for a worktree, named the worktree skill, or asked for an isolated workspace in the message that invoked you, that IS the explicit ask — proceed directly to Step 3 without re-prompting.

Otherwise, tell the user their options and wait for a reply:

"You're on <branch> in <repo>. I can set up an isolated worktree, or we can work directly here. What do you prefer?"

Routing:

• User explicitly asks for a worktree → proceed to Step 3
• User says work in place → skip to Step 4
• User gives no clear worktree preference → skip to Step 4 (default is in-place)
• Silence or unrelated reply → ask once more, then skip to Step 4 if still unclear

The default is always Step 4. Step 3 requires an explicit "yes, create a worktree" from the user.

Step 3: Create Worktree

You only reach this step because the user explicitly asked for a worktree in Step 2.

You have two mechanisms. Try them in this order.

3a. Native Worktree Tools (preferred)

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 4.

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 3b if you have no native worktree tool available.

3b. Git Worktree Fallback

Only use this if Step 3a does not apply — you have no native worktree tool available. 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.

Step 4: Project Setup

Auto-detect and run appropriate setup:

# Node.js
if [ -f package.json ]; then npm install; fi

# Rust
if [ -f Cargo.toml ]; then cargo build; fi

# Python
if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
if [ -f pyproject.toml ]; then poetry install; fi

# Go
if [ -f go.mod ]; then go mod download; fi

Step 5: Verify Clean Baseline

Run tests to ensure workspace starts clean:

# Use project-appropriate command
npm test / cargo test / pytest / go test ./...

If tests fail: Report failures, ask whether to proceed or investigate.

If tests pass: Report ready.

Report

If working in a worktree:

Worktree ready at <full-path>
Tests passing (<N> tests, 0 failures)
Ready to implement <feature-name>

If working in place:

Working in place on <branch> at <path>
Tests passing (<N> tests, 0 failures)
Ready to implement <feature-name>

Quick Reference

Situation	Action
Already in linked worktree	Skip creation, go to Step 4 (Step 1)
In a submodule	Treat as normal repo (Step 1 guard)
Normal repo, user wants in-place	Work in place, go to Step 4 (Step 2 default)
Normal repo, user asks for worktree	Create worktree (Step 3)
Native worktree tool available	Use it (Step 3a)
No native tool	Git worktree fallback (Step 3b)
.worktrees/ exists	Use it (verify ignored)
worktrees/ exists	Use it (verify ignored)
Both exist	Use .worktrees/
Neither exists	Check instruction file, then default .worktrees/
Global path exists	Use it (backward compat)
Directory not ignored	Add to .gitignore + commit
Permission error on create	Sandbox fallback, work in place
Tests fail during baseline	Report failures + ask
No package.json/Cargo.toml	Skip dependency install
User gives no worktree preference	Work in place (Step 2 default)
Plan touches multiple repos	Offer a matching worktree per repo, same branch name

Common Mistakes

Creating a worktree without being asked

• Problem: Agent creates a worktree because the skill was invoked, without the user requesting one
• Fix: Step 2 defaults to working in place. Only Step 3 creates, and only after explicit user request.

Fighting the harness

• Problem: Using git worktree add when the platform already provides isolation
• Fix: Step 1 detects existing isolation. Step 3a defers to native tools.

Skipping detection

• Problem: Creating a nested worktree inside an existing one
• Fix: Always run Step 1 before creating anything

Skipping ignore verification

• Problem: Worktree contents get tracked, pollute git status
• Fix: Always use git check-ignore before creating project-local worktree

Assuming directory location

• Problem: Creates inconsistency, violates project conventions
• Fix: Follow priority: existing > global legacy > instruction file > default

Proceeding with failing tests

• Problem: Can't distinguish new bugs from pre-existing issues
• Fix: Report failures, get explicit permission to proceed

Red Flags

Never:

• Create a worktree without the user explicitly asking for one
• Create a worktree when Step 1 detects existing isolation
• Use git worktree add when you have a native worktree tool (e.g., EnterWorktree). This is the #1 mistake — if you have it, use it.
• Skip Step 3a by jumping straight to Step 3b's git commands
• Create worktree without verifying it's ignored (project-local)
• Skip baseline test verification
• Proceed with failing tests without asking
• Infer worktree consent from the task description or plan — only an explicit user request counts

Always:

• Run Step 1 detection first
• Default to working in place (Step 2 → Step 4)
• Only create a worktree after explicit user request
• Prefer native tools over git fallback
• Follow directory priority: existing > global legacy > instruction file > default
• Verify directory is ignored for project-local
• Auto-detect and run project setup
• Verify clean test baseline

Integration

Called by:

• subagent-driven-development - Calls this to detect the workspace and optionally set up worktree isolation on request
• executing-plans - Calls this to detect the workspace and optionally set up worktree isolation on request
• Any skill that may use worktree isolation

Pairs with:

• finishing-a-development-branch - REQUIRED for cleanup after work complete