git-worktrees（Git 工作树）

Git Worktrees

Overview

Git worktrees allow you to have multiple working directories from the same repository, each with a different branch checked out. Work on multiple branches simultaneously without switching.

When to Use Worktrees

✅ Perfect For:

• Stacked PR development (one worktree per PR)
• Urgent hotfix while working on feature
• Parallel development on multiple features
• Code review in isolation
• Testing cross-branch interactions
• Running multiple dev servers simultaneously

⚠️ Consider Alternatives When:

• Limited disk space (worktrees duplicate working directory)
• Simple branch switching is sufficient
• Only working on one branch at a time

Basic Workflow

Create Worktree

New Branch:

# Create worktree with new branch
git worktree add ../worktrees/feature-auth -b feature/authentication

# Navigate to worktree
cd ../worktrees/feature-auth

Existing Branch:

# Create worktree from existing remote branch
git worktree add ../worktrees/feature-profile feature/user-profile

# Or from origin
git worktree add ../worktrees/review origin/feature/pr-to-review

List Worktrees

git worktree list

# Output:
# /Users/dev/project              abc123 [main]
# /Users/dev/worktrees/f-auth     def456 [feature/authentication]
# /Users/dev/worktrees/f-profile  ghi789 [feature/user-profile]

Remove Worktree

# Remove worktree (deletes directory)
git worktree remove ../worktrees/feature-auth

# Or manually delete directory and prune
rm -rf ../worktrees/feature-auth
git worktree prune

Directory Structure

Recommended layout:

/Users/dev/
├── my-project/              # Main repository
│   ├── .git/               # Git database
│   ├── src/
│   └── ...
└── my-project-worktrees/    # All worktrees here
    ├── feature-auth/       # feature/authentication branch
    ├── feature-profile/    # feature/user-profile branch
    ├── hotfix-urgent/      # hotfix/urgent-fix branch
    └── review-pr-123/      # Reviewing PR #123

Use Case: Stacked PRs

Perfect for stacked PR workflow - one worktree per PR:

# Create worktree for each PR in stack
git worktree add ../stack/pr-001 -b feature/001-base-auth
git worktree add ../stack/pr-002 -b feature/002-user-profile
git worktree add ../stack/pr-003 -b feature/003-admin-panel

# Work in each independently
cd ../stack/pr-001
# Implement base auth
git commit -am "feat: base authentication"
git push -u origin feature/001-base-auth

cd ../stack/pr-002
# Already on feature/002-user-profile branch
# Implement user profile (depends on pr-001)
git commit -am "feat: user profile with auth"
git push -u origin feature/002-user-profile

cd ../stack/pr-003
# Implement admin panel (depends on pr-002)
git commit -am "feat: admin panel"
git push -u origin feature/003-admin-panel

Use Case: Parallel Development

Run multiple dev servers simultaneously:

# Terminal 1: Main feature development
cd /project-worktrees/feature-new-ui
npm install
npm run dev  # Server on port 3000

# Terminal 2: Urgent hotfix (different branch)
cd /project-worktrees/hotfix-critical
npm install
npm run dev -- --port 3001  # Server on port 3001

# Both running simultaneously without branch switching

Use Case: Code Review

Review PRs in isolation:

# Create worktree for PR review
git worktree add ../review/pr-456 origin/feature/user-auth

cd ../review/pr-456
npm install
npm test
npm run dev

# Review code, test functionality
# When done, remove worktree
cd /main-project
git worktree remove ../review/pr-456

Updating Stacked PRs with Worktrees

When base PR changes, update chain across worktrees:

# PR-001 got feedback
cd /stack/pr-001
git pull origin feature/001-base-auth
# Make changes, push

# Update PR-002 (in separate worktree)
cd /stack/pr-002
git rebase feature/001-base-auth
git push --force-with-lease origin feature/002-user-profile

# Update PR-003 (in separate worktree)
cd /stack/pr-003
git rebase feature/002-user-profile
git push --force-with-lease origin feature/003-admin-panel

Managing Dependencies

Shared node_modules (Save Disk Space)

Option 1: Symlink

cd /worktrees/feature-auth
ln -s /main-project/node_modules node_modules

Option 2: Separate Install

cd /worktrees/feature-auth
npm install  # Independent node_modules

Trade-off:

• Symlink: Less disk space, may have version conflicts
• Separate: More disk space, guaranteed isolation

Best Practices

1. Naming Convention

# Use descriptive, consistent names
git worktree add ../worktrees/feature-authentication feature/authentication
git worktree add ../worktrees/hotfix-security hotfix/security-patch

2. Location Strategy

# Keep worktrees outside main repo
/Users/dev/project/              # Main repo (never delete)
/Users/dev/project-worktrees/    # All worktrees here (safe to delete)

3. Cleanup Discipline

# When PR merged, remove worktree immediately
git worktree remove path/to/worktree

# Periodically check for stale worktrees
git worktree prune

# Delete merged branches
git branch -d feature/old-branch
git push origin --delete feature/old-branch

4. One Branch Per Worktree

❌ WRONG: Switching branches in worktree defeats the purpose
✅ CORRECT: Each worktree permanently on one branch

Common Commands

# Create worktree with new branch
git worktree add <path> -b <branch>

# Create worktree from existing branch
git worktree add <path> <branch>

# List all worktrees
git worktree list

# Remove worktree
git worktree remove <path>

# Clean up stale references
git worktree prune

# Move worktree to different location
git worktree move <old-path> <new-path>

Troubleshooting

Issue: "fatal: '' is already checked out"

Cause: Branch is checked out in another worktree

Solution:

# List worktrees to find where branch is checked out
git worktree list

# Either work in existing worktree or remove it first
git worktree remove <path-to-old-worktree>

Issue: Disk space concerns

Solution:

• Use symlinks for node_modules
• Remove worktrees when PRs merged
• Run git worktree prune regularly
• Consider using sparse-checkout for large repos

Issue: IDE confusion with multiple worktrees

Solution:

• Open each worktree as separate workspace
• Use IDE's multi-window/split-workspace features
• Name worktrees descriptively for easy identification

Agent Instructions

When delegating worktree setup to version-control agent:

Task: Create worktrees for stacked PR development

Requirements:
- Create 3 worktrees in /project-worktrees/
- Worktree 1: pr-001 with branch feature/001-base-auth
- Worktree 2: pr-002 with branch feature/002-user-profile
- Worktree 3: pr-003 with branch feature/003-admin-panel

Commands:
git worktree add ../project-worktrees/pr-001 -b feature/001-base-auth
git worktree add ../project-worktrees/pr-002 -b feature/002-user-profile
git worktree add ../project-worktrees/pr-003 -b feature/003-admin-panel

Verification: git worktree list should show all 3 worktrees

Benefits

✅ No Branch Switching: Work on multiple branches without git checkout ✅ Parallel Servers: Run multiple dev environments simultaneously ✅ Preserve State: Build artifacts and node_modules stay per-branch ✅ Safer Reviews: Test PRs without affecting main working directory ✅ Faster Context Switch: Jump between worktrees instead of rebasing

Related Skills

• stacked-prs - Combine worktrees with stacked PR workflow
• git-workflow - General git branching patterns
• code-review - Review code in isolated worktrees