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

Check in priority order

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

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. ~/.claude/worktrees/<project-name>/ (global location)

Which would you prefer?

Safety Verification

For Project-Local Directories (.worktrees or worktrees)

MUST verify .gitignore before creating worktree:

Check if directory pattern in .gitignore

grep -q "^.worktrees/$" .gitignore || grep -q "^worktrees/$" .gitignore

If NOT in .gitignore:

Per Jesse's rule "Fix broken things immediately":

• Add appropriate line to .gitignore

• Commit the change

• Proceed with worktree creation

Why critical: Prevents accidentally committing worktree contents to repository.

For Global Directory (~/.claude/worktrees)

No .gitignore verification needed - outside project entirely.

Creation Steps

1. Detect Project Name

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

2. Create Worktree

Determine full path

case $LOCATION in .worktrees|worktrees) path="$LOCATION/$BRANCH_NAME" ;; /.claude/worktrees/*) path="/.claude/worktrees/$project/$BRANCH_NAME" ;; esac

Create worktree with new branch

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

3. Run 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

4. Verify Clean Baseline

Run tests to ensure worktree starts clean:

Examples - 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.

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 .gitignore)

worktrees/ exists Use it (verify .gitignore)

Both exist Use .worktrees/

Neither exists Check CLAUDE.md → Ask user

Directory not in .gitignore Add it immediately + commit

Tests fail during baseline Report failures + ask

No package.json/Cargo.toml Skip dependency install

Common Mistakes

Skipping .gitignore verification

• Problem: Worktree contents get tracked, pollute git status

• Fix: Always grep .gitignore before creating project-local worktree

Assuming directory location

• Problem: Creates inconsistency, violates project conventions

• Fix: Follow priority: existing > CLAUDE.md > ask

Proceeding with failing tests

• Problem: Can't distinguish new bugs from pre-existing issues

• Fix: Report failures, get explicit permission to proceed

Hardcoding setup commands

• Problem: Breaks on projects using different tools

• Fix: Auto-detect from project files (package.json, etc.)

Example Workflow

You: I'm using the using-git-worktrees skill to set up an isolated workspace.

[Check .worktrees/ - exists] [Verify .gitignore - contains .worktrees/] [Create worktree: git worktree add .worktrees/auth -b feature/auth] [Run npm install] [Run npm test - 47 passing]

Worktree ready at /Users/jesse/myproject/.worktrees/auth Tests passing (47 tests, 0 failures) Ready to implement auth feature

Red Flags

Never:

• Create worktree without .gitignore verification (project-local)

• Skip baseline test verification

• Proceed with failing tests without asking

• Assume directory location when ambiguous

• Skip CLAUDE.md check

Always:

• Follow directory priority: existing > CLAUDE.md > ask

• Verify .gitignore for project-local

• Auto-detect and run project setup

• Verify clean test baseline

Integration

Called by:

• brainstorming (Phase 4) - REQUIRED when design is approved and implementation follows

• Any skill needing isolated workspace

Pairs with:

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

• executing-an-implementation-plan - Work happens in this worktree