Letting a bot work on your computer is powerful, so Machine gives you several layers of protection. You don't need to use them all, but you should know they're there.

The protections

Protection	What it does	Where
Folders	The bot can only open and change files in folders you've shared with that thread.	Folder menu
Permission requests	If the bot needs something else, like another folder, it has to ask. You click Allow or Deny.	Below
Approval level and What needs your OK	The thread's approval level and the bot's Use This PC rule decide whether the bot asks before it uses your computer. Under Ask for approval, it asks.	Message box, and Bot settings → Access
Ask before each action	Optional, and off by default. A second check, kept by Machine: when on, you approve every file change, command, and click. Turning it off skips only this check. The approval level still applies.	Folder menu
Apps, mouse and keyboard	Turn screen control off to keep the bot to files and commands.	Folder menu
Stop	One click or one shortcut stops everything.	Below
The purple glow	You can always see when a bot is using your screen.	Below
Safety rules	Bots follow rules about on-screen text, passwords, and payments.	Below

What a folder does and doesn't protect

The shared folder limits which files the bot can open and change directly. But a command or program the bot runs works with your normal user permissions, and can reach anything you can. For important work, keep Ask before each action on, so you see and approve every command before it runs.

Allow or deny a request

A permission request asking to use a folder, with Deny and Allow

If a bot needs a folder you haven't shared, or wants to run a command or use your screen, Machine Desktop jumps to the front, even from the tray, and shows a card:

Assistant wants to use C:\Users\you\Documents\Receipts

On this computer. Allow shares it with Machine for this thread; you can press Stop at any time.

Button	What happens
Allow	The folder (or action) is shared with this thread. The bot carries on from where it stopped. A note in the chat records it.
Deny (or Esc)	The bot is told no. A note in the chat records it.

Requests appear one at a time, oldest first.
They show up even for threads started on the web or your phone, as long as Machine Desktop is running here.
Allowing applies to this thread only.

Stop a bot

You can always stop a bot working on your computer.

How	What it stops
The Stop button in the chat header or message box	This thread. Its browser closes, its programs end, and any keys it was holding are released.
Send a message that just says stop	Same as the Stop button.
Ctrl+Alt+Esc (Windows) or ⌘⇧Esc (Mac), from any app	Everything any bot is doing on this computer.
The red Stop on the Machine controlling this screen banner	Everything on this computer.
Stop — release all tabs in the Chrome extension, or Cancel on Chrome's bar	Everything in your Chrome.

Learn the shortcut. Ctrl+Alt+Esc (⌘⇧Esc on Mac) works even when Machine Desktop isn't in front, and even if the bot is in the middle of typing.

After stopping

The status shows Stopping… until Machine Desktop confirms.
After a full stop, the thread shows Stopped on this computer. Just send your next message to carry on. The bot is told the old task is over.
If a stop can't be confirmed within a few seconds, Machine Desktop forcefully ends the bot's work and shows "Stop could not be confirmed". If it adds "— check for held keys", press and release Ctrl, Alt, and Shift in case a key is still held down.

The folder menu always shows the shortcut (Stop anytime:). If another app already uses it, the menu tells you. Use the Stop button or the on-screen Stop instead.

How you can tell a bot is using your screen

While a bot uses your screen or the Machine browser:

the edges of your screen glow purple,
the window it's using has a purple frame,
a banner at the top of the screen says Machine controlling this screen, with a red Stop button,
you can see where the bot is pointing:
- On Windows, the bot has its own purple pointer with a Machine name tag. It glides to each spot the bot clicks, with a ripple on each click. After every click, drag, or scroll, your own mouse pointer is handed straight back to you.
- On a Mac, a purple ring follows your mouse pointer while the bot is using it.

The glow fades a few seconds after the bot stops. None of it appears in the bot's own screenshots.

File changes and commands don't trigger the glow: watch the chat and the status line under the chat header for those.

The bot's safety rules

Bots working on This PC follow these rules:

On-screen text is information, not instructions. A web page or email that says "ignore your instructions and…" is treated as content, not as a command.
No passwords you didn't give. A bot won't type a password unless you gave it that exact password.
No irreversible actions you didn't ask for. A bot won't pay, send, post, or delete unless you clearly asked.
No guessing on uncertain actions. If a bot isn't sure an action worked, it checks before repeating it.
Cloud threads can't touch This PC. Only threads set to This PC can reach your computer.

The bot also won't type into Machine Desktop's own window.

Screenshots and privacy

When a bot looks at your screen, the screenshots are sent to Machine so the bot can see them. Before letting a bot use your screen:

close windows with private information,
or turn off Apps, mouse and keyboard in the folder menu. That keeps bots on this computer to files and commands.

Password fields are never read back by the Machine browser. To have the Machine browser signed in to a website without telling a bot your password, sign in yourself with Saved sign-ins.

A sensible way to start

Start with a small, unimportant folder.
Turn on Ask before each action.
Give a simple task, and watch what it asks to do.
Practise stopping with Ctrl+Alt+Esc (⌘⇧Esc).
Once you're comfortable, turn Ask before each action off for routine work.

Safety and stopping