Using git worktrees

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.

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 CLAUDE.md / AGENTS.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 config 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

MUST verify directory is ignored before creating worktree:

git check-ignore -q .worktrees 2>/dev/null || git check-ignore -q worktrees 2>/dev/null

If NOT ignored:

1. Add appropriate line to .gitignore
2. Commit the change
3. Proceed with worktree creation

Why critical: Prevents accidentally committing worktree contents to repository.

Creation Steps

1. Detect Project Name

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

2. Create Worktree

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

3. Run Project Setup

Auto-detect and run appropriate setup:

if [ -f package.json ]; then npm install; fi
if [ -f Cargo.toml ]; then cargo build; fi
if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
if [ -f go.mod ]; then go mod download; fi

4. Verify Clean Baseline

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 config → Ask user
Directory not ignored	Add to .gitignore + commit
Tests fail during baseline	Report failures + ask

Common Mistakes

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

Assuming directory location — violates project conventions

Proceeding with failing tests — can't distinguish new bugs from pre-existing issues

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

Always:

• Follow directory priority: existing > config > ask
• Verify directory is ignored for project-local
• Auto-detect and run project setup
• Verify clean test baseline

Verification

• Directory choice followed the priority order: existing directory, then config preference, then asking
• A project-local worktree directory was verified gitignored before the worktree was created
• Project setup was auto-detected and run in the new worktree
• The baseline test run happened — failures were reported and confirmed, never skipped past
• The final report names the worktree path and the test status