skill shared-brain
Two people.
One Claude workspace.
Claude Code keeps everything it knows about your business in plain files in a folder. Put that folder in Drive or Dropbox and a second person can work from it too. What you do not get is any idea of who is who: both people are the same anonymous user, everyone can open everything, and nothing records who changed what.
This skill adds the missing part. It asks the new person their name, gives each person specific areas of the business to work in, writes down what everyone did, and seals its own rulebook so nobody can quietly promote themselves.
Get it on GitHub Read the limits firstWhy it exists
Claude has a Team plan. It gives you seats, single sign-on and a usage dashboard. It does not give you per-person permissions on the files inside a project, and it does not give you a record of who edited what. So paying for it does not solve this.
I went looking for something that did and found the pieces scattered: Claude Code can block paths, macOS can sandbox a folder, people have written hooks that protect a single file. Nobody had put identity, areas, and an audit trail together. So I built it, for a family business sharing one workspace, and then made it free.
What it does
Asks who is at the keyboard
The first time a new computer opens the shared folder, Claude asks the person their name and remembers that machine. No accounts, no passwords, nothing to sign up for.
Permissions per area of the business
You define the areas that matter to you: finance, clients, marketing, content, operations. Each role gets a list of areas, and inside an area a person reads and writes freely. Outside it, Claude will not open the file for them, and it will not go around the rule with a terminal command either.
Writes down who did what
Every change is logged against a name. Ask what someone did this week and get a real list, including the things they tried to open and were not allowed to.
Seals its own rulebook
The file that says who is admin is signed with a key that never leaves your machine. If anyone edits it by hand to give themselves more access, the seal breaks, the workspace locks, and it tells you. Hiding that file would not work, because everyone's Claude has to read it. Sealing it does.
What it cannot do
If the folder is synced to someone's computer, they have every file on their disk, whether or not Claude will open it for them. This skill stops Claude. It does not stop a person opening the file in Finder.
For anything that genuinely must not reach someone's machine, there is a command that moves that area out of the shared folder entirely, so their copy never receives it. Not blocked. Never sent.
I would rather you know that before you install it than after. The full threat model is written out in plain language in the repo, including the parts that are uncomfortable.
Installing it
It is Python that ships with your Mac, plus tools already on it. Nothing to install, no account, no service in the middle, and it never calls out to the internet.
Copy the folder into your project, add four lines to your Claude settings so it runs on every session, then turn it on:
/shared-brain init --name "Your Name"
That makes you the admin. To bring someone in:
/shared-brain add "Their Name"
Send them the folder. The next time they open Claude in it, it asks their name and the rest happens on its own. The exact steps are in the repo.
Installation stepsMost of what I build ends up looking like this
A small, specific thing that removes one real problem, built because the alternative was paying for something that did not actually solve it. If that is the kind of help you want inside your own business, that is what I do.
or just take the code, it is yours
Talk to me