richfrem/using-git-worktrees

Source: Ported from obra/superpowers by Jesse Vincent. Adapted for the agent-plugins-skills ecosystem. Original concepts and Iron Laws credit belongs to Jesse.

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. ~/.config/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:

# Check if directory is ignored (respects local, global, and system gitignore)
git check-ignore -q .worktrees 2>/dev/null || git check-ignore -q worktrees 2>/dev/null

If NOT ignored:

Fix broken things 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

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"
    ;;
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:

# 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 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 | | No package.json/Cargo.toml | Skip dependency install |

Common Mistakes

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 -> 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

Example Workflow

<example> I need to work on auth task. Set up a git worktree.

[Check .worktrees/ - exists] [Determine path: .worktrees/auth] [git worktree add .worktrees/auth -b task/auth] </example>

<example> I'm using the using-git-worktrees skill to set up a separate workspace.

[Check .worktrees/ - exists] [Verify ignored - git check-ignore confirms .worktrees/ is ignored] [Add worktree: git worktree add .worktrees/auth -b task/auth] [Run npm install] [Run npm test - 47 passing]

Worktree ready at /path/to/project/.worktrees/auth Tests passing (47 tests, 0 failures) Ready to implement auth task </example>

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
• Skip CLAUDE.md check

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

Pairs with:

• finishing-a-development-branch - Required for cleanup after work complete
• verification-before-completion - Verify work before finishing the branch
• requesting-code-review - Review before merging

spec-kitty integration: When using spec-kitty's SDD lifecycle, this skill complements the .worktrees/ convention already established. The ORCHESTRATOR owns git operations (merge, cleanup); INNER_AGENT work packages each get isolated worktrees via this skill. It replaces the standard git checkout workflow with an isolated git worktree workflow.