using-git-worktrees

What this skill does

# Using Git Worktrees

## Overview

Git worktrees create isolated workspaces sharing the same repository, allowing work on multiple branches simultaneously without switching.

**Core principle:** Systematic directory selection + safety verification = reliable isolation.

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

## Directory Selection Process

Follow this priority order:

### 1. Check Existing Directories

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

**If found:** Use that directory. If both exist, `.worktrees` wins.

### 2. Check CLAUDE.md

```bash
grep -i "worktree.*director" CLAUDE.md 2>/dev/null
```

**If preference specified:** Use it without asking.

### 3. Ask User

If no directory exists and no CLAUDE.md preference:

```
No worktree directory found. Where should I create worktrees?

1. .worktrees/ (project-local, hidden)
2. ~/worktrees/<project-name>/ (global location)

Which would you prefer?
```

## Safety Verification

### For Project-Local Directories (.worktrees or worktrees)

**MUST verify directory is ignored before creating worktree:**

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

**If NOT ignored:**

Fix immediately:
1. Add appropriate line to .gitignore
2. Commit the change
3. Proceed with worktree creation

**Why critical:** Prevents accidentally committing worktree contents to repository.

### For Global Directory (~/worktrees/)

No .gitignore verification needed — outside project entirely.

## Creation Steps

### 1. Detect Project Name

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

### 2. Create Worktree

```bash
# Create worktree with new branch
git worktree add "$path" -b "$BRANCH_NAME"
cd "$path"
```

### 3. Run Project Setup

Auto-detect and run appropriate setup:

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

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

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

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

### 4. Verify Clean Baseline

Run tests to ensure worktree starts clean:

```bash
pytest / npm test / cargo test / go test ./...
```

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

**If tests pass:** Report ready.

### 5. Report Location

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

## Quick Reference

| Situation | Action |
|-----------|--------|
| `.worktrees/` exists | Use it (verify ignored) |
| `worktrees/` exists | Use it (verify ignored) |
| Both exist | Use `.worktrees/` |
| Neither exists | Check CLAUDE.md → Ask user |
| Directory not ignored | Add to .gitignore + commit |
| Tests fail during baseline | Report failures + ask |

## Requirements Integration

Creating a worktree naturally creates a feature branch, which satisfies the `protected_branch` requirement. This means you can start editing immediately after worktree setup.

## Red Flags

**Never:**
- Create worktree without verifying it's ignored (project-local)
- Skip baseline test verification
- Proceed with failing tests without asking
- Assume directory location when ambiguous

**Always:**
- Follow directory priority: existing > CLAUDE.md > ask
- Verify directory is ignored for project-local
- Auto-detect and run project setup
- Verify clean test baseline

## Integration

**Called by:**
- `requirements-framework:executing-plans` — Before executing tasks in an isolated workspace
- `requirements-framework:subagent-driven-development` — Before executing any tasks

**Pairs with:**
- `requirements-framework:finishing-a-development-branch` — Cleans up worktree after work complete