using-git-worktrees

name	using-git-worktrees
description	Use when starting feature work that needs isolation from the current workspace, or before executing implementation plans — creates isolated git worktrees with safety verification.
metadata	{"version":"2.0.0","author":"erebus","tags":["software-development","git","workflow","isolation"]}

Using Git Worktrees

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

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

When to Use

• Starting a new feature that should not pollute the current workspace
• Before executing an implementation plan (required before writing-plans output)
• Working on a bug fix in parallel with other work
• Any time you need a clean baseline environment

Directory Selection Process

Follow this priority order:

1. Check Existing Directories

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 Project Config

grep -i "worktree.*director" CLAUDE.md 2>/dev/null
grep -i "worktree.*director" .erebus.toml 2>/dev/null

If a preference is specified: use it without asking.

3. Ask User

If no directory exists and no config preference:

No worktree directory found. Where should I create worktrees?

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

Which would you prefer?

Safety Verification

For Project-Local Directories

MUST verify the directory is ignored before creating a worktree:

git check-ignore -q .worktrees 2>/dev/null || echo "NOT IGNORED"

If NOT ignored: add to .gitignore and commit that change first.

Why critical: prevents accidentally committing worktree contents to the 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 on new branch
git worktree add .worktrees/<branch-name> -b <branch-name>
cd .worktrees/<branch-name>

# 3. Run project setup (auto-detect)
[ -f package.json ]      && npm install
[ -f requirements.txt ]  && pip install -r requirements.txt
[ -f pyproject.toml ]    && pip install -e ".[all]" 2>/dev/null || pip install -e .
[ -f Cargo.toml ]        && cargo build
[ -f go.mod ]            && go mod download

# 4. Verify clean baseline (run existing tests)
# Use the project's test command

Baseline Verification

Run the project's test suite before starting:

pytest / npm test / cargo test / go test ./...

If tests fail: Report failures and ask whether to proceed or investigate first. If tests pass: Report ready.

Report Format

Worktree ready at <full-path>
Branch: <branch-name>
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 config → ask user
Directory not ignored	Add to .gitignore + commit first
Tests fail at baseline	Report + ask before proceeding

Common Mistakes

Skipping ignore verification — worktree contents get tracked, pollute git status.

Proceeding with failing baseline tests — you can't distinguish new bugs from pre-existing ones.

Hardcoding setup commands — always auto-detect from project files.

Cleanup

When work is complete (handled by finishing-a-development-branch skill):

git worktree remove .worktrees/<branch-name>