The security model

Agents: claude, codex, opencode · On: phone, desktop

Anything that can log in to VCode runs code as your user on that machine. A login can put any tab at Full, where the agent runs anything without asking, so a login is full trust. VCode's security is about who can log in, not about limiting what a logged-in session can do.

Why you would use it

Before you open VCode to the internet or pair a phone, you should know what a login is worth and what stands in front of it.

How to use it

1. Keep your fezu.dev account to yourself, and the email inbox behind it. You sign in to the account with a code sent to that email. A device signed in to the account opens every box linked to it, with no code from the box, and can put any tab on those boxes at Full (add-a-phone).
2. Keep the box's AUTH_TOKEN secret. It is what the v-code CLI and scripts on the machine send; treat it like the password to a shell there. If it leaks, change it and restart VCode.
3. Remove a device you no longer use from Settings. A device you remove stays out of that box until it pairs again with a code from the box. To stop it on every box, remove it from your account on fezu.dev.

What you see

• A browser that opens the box's own address sees a page that points at app.fezu.dev, and nothing else.
• A device logged in to the app sees every thread, the shell and the files on every box on the account, and can do anything you can do in a terminal.

Limits and known gaps

• Your email is the key to every box. Anyone who gets a sign-in code from your inbox signs in to your account and opens every box on it, tabs at Full included. No box can be set to keep a signed-in device out.
• Login is full trust. There is no read-only mode, no permission per thread and no sandbox. A session opens a shell, reads and writes any file your user can, and runs any command.
• A session changes files directly, not only through an agent. It can edit, create, rename and delete files in any folder your user can write. A folder is deleted with everything in it, and there is no trash.
• Anything running in a thread, including the agent, can talk to VCode as you.

Related

• use-the-app: logging in on a new device
• reach-it-from-a-phone: how a phone gets to a box
• add-a-phone: removing a device, and pairing it again
• switch-accounts: which account the app is on, and switching
• permission-levels: what Ask stops, and what it does not
• shell-mode: the shell a session opens
• edit-a-file: the file writes a session makes
• manage-files: create, rename and delete from the explorer
• todo-list: an agent in a thread talking back to VCode