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

1. Determine what the path for the required workree will be "/"
2. Are we already there? Is it a git worktree? If so, report and exit.
3. If we're are in the wrong worktree, report and exit.
4. Identify parent worktree directory using priority:
   • Existing worktree parent directory
   • AGENTS.md preference
   • User prompt
5. Ensure project-local directories are in .gitignore
6. Create worktree, run setup, verify clean baseline

1. Check if there is an existing worktree parent directory

# Check in priority order
ls -d "../$(git rev-parse --path-format=absolute --git-common-dir | xargs dirname).worktrees" 2>/dev/null      # Alternative

If found: Use that directory.

2. Check AGENTS.md

grep -i "worktree.*director" AGENTS.md 2>/dev/null

If preference specified: Use it without asking.

3. Ask User

If no directory exists and no AGENTS.md preference:

No worktree directory found. Where should I create worktrees?

1. ../$(basename "$(git rev-parse --show-toplevel)").worktrees (project-local, hidden)
2. ~/.locals/share/<project-name>.worktrees/ (global location)

Which would you prefer?

Creation Steps

1. Detect Project Name

project=$(git rev-parse --path-format=absolute --git-common-dir | xargs dirname)

2. Create Worktree

# Create worktree with new branch
path="../${project}.worktrees/${feature_name}"
mkdir -p "$path"
git worktree add "$path" -b "$BRANCH_NAME"
cd "$path"

3. Run Project Setup

Auto-detect and run appropriate setup:

# if Justfile
if [ -f Justfile ]; then just setup; fi

# if Mise
if [ -f .mise.toml ]; then mise setup; exit 0; fi

# Node.js (npm)
if [ -f package.json ]; then npm install; fi
# Node.js (yarn)
if [ -f package.json ]; then yarn install; fi
# Node.js (bun)
if [ -f package.json ]; then bun install; fi
# Node.js (pnpm)
if [ -f package.json ]; then pnpm 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
# if Justfile
if [ -f Justfile ]; then just test; fi

if [ -f .mise.toml ]; then
  mise check
  exit 0
fi

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-identifier>

Quick Reference

Situation	Action
No worktrees yet	Use ../<projectname>.worktrees/
Neither exists	Check AGENTS.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

Assuming directory location

• Problem: Creates inconsistency, violates project conventions
• Fix: Follow priority: existing > AGENTS.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 ../<projectname>.worktrees/ - exists]
[Create worktree: git worktree add ../<projectname>.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 within existing workspace
• Skip baseline test verification
• Proceed with failing tests without asking
• Assume directory location when ambiguous
• Skip AGENTS.md check

Always:

• Follow directory priority: existing > AGENTS.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-plans or subagent-driven-development - Work happens in this worktree