Using Git Worktrees Lite

Using Git Worktrees Lite

Overview

Create an isolated worktree from the current branch with a build/compile check instead of running tests.

Core principle: Confirm base branch + safe worktree directory + compile-only verification.

Announce at start: "I'm using the using-git-worktrees-lite skill to set up an isolated workspace."

The Process

Step 0: Normalize to Repo Root (Avoid CWD Pitfalls)

Worktrees are very sensitive to your current working directory (CWD) when you use relative paths like .worktrees/....

Always capture the repo root and ensure you are operating from there before creating worktrees:

repo_root=$(git rev-parse --show-toplevel)
cd "$repo_root"

Step 1: Capture Base Branch (Merge Target)

base_branch=$(git branch --show-current)

Confirm with the user that this is the branch to merge back into. Do not assume main or master.

Step 2: Select Worktree Directory

Follow this priority order:

ls -d .worktrees 2>/dev/null
ls -d worktrees 2>/dev/null

If neither exists, check AGENTS.md for a preferred location. If still unknown, ask the user.

Step 3: Verify Directory is Ignored (Project-Local Only)

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

If not ignored, add the directory to .gitignore and commit. If you cannot commit now, stop and ask.

Step 4: Create Worktree From Base Branch

Use a naming convention to preserve the base branch in the worktree branch name:

<base-branch>__wt__<worktree-branch>

Example:

feature/auth__wt__login

# Example: git worktree add .worktrees/feature-auth__wt__login -b feature-auth__wt__login "$base_branch"
git worktree add "$path" -b "$branch_name" "$base_branch"
cd "$path"

Step 5: Run Project Setup (Auto-detect)

# Node.js
if [ -f package.json ]; then npm install; fi

# Rust
if [ -f Cargo.toml ]; then cargo fetch; 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

# Java (Maven)
# No dependency install step needed here

Step 6: Build/Compile Check (No Tests)

1. Check AGENTS.md for project build/compile commands. If present, follow it.
2. Otherwise use default build/compile commands:

# Node.js (requires build script)
if [ -f package.json ]; then npm run -s build; fi

# Rust
if [ -f Cargo.toml ]; then cargo build; fi

# Go
if [ -f go.mod ]; then go build ./...; fi

# Python
if [ -f pyproject.toml ] || [ -f requirements.txt ]; then python -m compileall .; fi

# Java (Maven)
if [ -f pom.xml ]; then mvn -q clean compile; fi

If no build command is available (e.g., no npm build script), ask the user for the correct command.

If the build fails, report the failure and ask whether to proceed or investigate.

Step 7: Report Result

Worktree ready at <path>
Base branch: <base-branch>
Build/compile: <result>

Step 8: Return to Repo Root (Important)

Unless the user explicitly asks you to stay in the worktree to debug, return to the repo root at the end.

This prevents follow-up commands from accidentally running in the last worktree (and prevents creating nested worktrees due to relative paths).

cd "$repo_root"

Quick Reference

Common Mistakes

Assuming main/master as base branch

• Problem: Merges into the wrong branch
• Fix: Capture and confirm current branch as base

Skipping ignore verification

• Problem: Worktree files show up in git status
• Fix: git check-ignore before creating worktree

Running tests instead of compile-only

• Problem: Violates the lite workflow
• Fix: Only run build/compile checks

Skipping build because no obvious command

• Problem: Misses required compilation verification
• Fix: Ask for the project-specific build command

Merging from the worktree branch directory

• Problem: Base branch is already checked out elsewhere; merge fails
• Fix: Merge from the base-branch worktree directory

Staying in the last worktree directory

• Problem: Follow-up tasks run in the wrong directory; relative worktree paths can create nested worktrees
• Fix: Always cd "$repo_root" after setup/build unless debugging is needed

Rationalization Table

Red Flags

• "I'll just merge this back to main"
• "Tests are faster than figuring out the build"
• "No need to confirm the base branch"

Example

base_branch=$(git branch --show-current)
# Confirm base_branch with user
repo_root=$(git rev-parse --show-toplevel)
cd "$repo_root"
mkdir -p .worktrees
path=.worktrees/feature-x
branch_name=feature-x

git worktree add "$path" -b "$branch_name" "$base_branch"
cd "$path"

npm install
npm run -s build

cd "$repo_root"