Parallel Claudes with cw

In 02 - AI Driven Development I talked about long-running agents and how to keep them off your main attention thread. But there's a practical problem I didn't address: what happens when two Claude Code sessions touch the same files?

They conflict. One overwrites the other. You end up with broken state and wasted tokens.

The worktree trick

Git has a built-in feature called worktrees that lets you check out multiple branches of the same repo simultaneously, each in its own directory. They share the same .git history but have completely isolated working trees.

This is the foundation of cw (Claude Worktree), a tiny Bash CLI we built that manages isolated git worktrees specifically for running parallel Claude Code sessions.

curl -fsSL https://raw.githubusercontent.com/joyco-studio/cw/main/install.sh | bash

It installs a single shell script to ~/.local/bin/cw and sources it in your shell rc. No dependencies beyond Git and the Claude CLI.

How it works

Spin up a new session

cw new auth "implement OAuth2 with GitHub provider"

This does a few things:

1. Creates a directory at <repo>/.worktrees/auth
2. Checks out a new branch cw/auth from your base branch
3. Detects your package manager and installs dependencies
4. Opens Claude Code in the isolated directory with your prompt

The key detail: Claude is now working in a completely separate copy of your project. It can modify files, run builds, break things, none of it touches your main working directory.

Run multiple sessions at once

cw new auth --open "implement OAuth2 with GitHub provider"
cw new api --open "build REST endpoints for the dashboard"
cw new tests --open "add integration tests for the billing module"

Three Claude sessions, three isolated worktrees, three branches. All running in parallel without conflicts.

Check what's running

cw ls

Active worktrees:
 
  * auth   (cw/auth, 3 ahead)
    /Users/you/project/.worktrees/auth
 
  * api    (cw/api, 7 ahead)
    /Users/you/project/.worktrees/api
 
  * tests  (cw/tests, 2 ahead)
    /Users/you/project/.worktrees/tests

Navigate between them

cw cd auth

Ship the work

When a session is done, you have two options:

Create a PR:

cw merge auth

This pushes the cw/auth branch and opens a PR via the GitHub CLI.

Squash merge locally:

cw merge auth --local

This squash-merges the branch into your base branch with a feat: auth commit message, then cleans up.

A fictional Tuesday

Here's what a real session might look like. You're the lead on a SaaS dashboard. It's Tuesday morning, and there are three tickets on the board:

• DASH-41: Add workspace invite flow
• DASH-42: Migrate analytics queries to the new schema
• DASH-43: Fix timezone bug in the activity feed

You start with the invite flow since it needs the most oversight:

cw new invites --no-open
cw cd invites
claude

You're working interactively with Claude on the invite flow, designing the schema, iterating on the email template, reviewing each step. This is your main attention thread.

Meanwhile, the analytics migration is well-scoped. The new schema is documented, and it's mostly mechanical find-and-replace across query files. You kick that off in the background:

cw new analytics --open "migrate all analytics queries from v1 to v2 schema. \
  refer to docs/analytics-v2-migration.md for the field mapping"

The timezone fix is also straightforward, there's even a failing test for it:

cw new tz-fix --open "fix the timezone bug in the activity feed. \
  there's a failing test in tests/activity-feed.test.ts that reproduces it"

You continue working on the invite flow. Twenty minutes later:

cw ls

Active worktrees:
 
  * invites    (cw/invites, 4 ahead)
  * analytics  (cw/analytics, 12 ahead)
  * tz-fix     (cw/tz-fix, 2 ahead)

The timezone fix has 2 commits. You check it:

cw cd tz-fix
git log --oneline cw/tz-fix --not main

Looks good. Ship it:

cw merge tz-fix

The analytics migration has 12 commits, Claude went through every query file. You review the diff, it's clean. Ship that too:

cw merge analytics

Back to your main thread:

cw cd invites

You finish up the invite flow, review it, and merge:

cw merge invites

Three tickets closed. One required your full attention, two ran autonomously. No conflicts, no context switching, no broken state.

The full command reference

Links

• GitHub Repository
• Install instructions