How Spaces works

Computers and Spaces, bring-your-own compute, where a Space can run, and how you and your agents reach it directly or through the relay.

Cua Spaces connects three things: the computers you own, the Spaces on them, and the people and agents who use those Spaces.

Computers and Spaces#

A computer (the app calls it a machine) is a Mac, Windows or Linux computer you own or rent. A Space is one desktop on a computer, set up for a task. A Space is a container or a VM, or the computer's own desktop.

Cua doesn't rent computers. You bring them, and your cloud provider bills you for any VM you run in your own account. Cua provides the app, sharing and the relay that lets your devices reach your computers.

Where a Space runs#

Location	What it is
This computer	A container or VM on the Mac, Windows or Linux PC you are using.
Another of your machines	A computer you added that provides Spaces, such as a spare Mac mini.
Your own cloud	A VM in your own AWS, Google Cloud or Modal account. See Use your own cloud.

Cua Cloud, the hosted option, has ended. See Cua Cloud (Fleets) has ended.

Every Space runs cua-spacesd. It streams the screen, takes input through Cua Driver, and receives teleported apps and files.

How you reach a Space#

Directly. On the same network, or over Tailscale, your device connects to the Space with its address and a token. No account is needed, and the traffic doesn't use the relay.
Through the relay. A machine set up with cua host setup joins the cua.ai relay with an outbound connection, so you don't open ports. Your enrolled devices, and people you share a Space with, reach it through the relay. Relay use counts toward your plan's live sessions and relay hours.

For what the relay can and can't see, see What the relay can see.

Space ids#

Kind	Id	Comes from
Local	`local:<name>`	`spaces.create(options)`: a new Space, on this machine by default
Direct	`direct:<host:port>`	`spaces.add(url, token)`: an existing machine
Relay	`relay:<machine-id>`	Your machines set up with `cua host setup`, listed automatically

The app, the cua CLI, the SDKs and cua daemon share one registry (~/.cua/spaces.json). Relay machines come from your account's directory and are never written to spaces.json.

Who can do what#

You own your computers and the Spaces on them. You can share a Space with another account as a viewer or an editor, and with Teams a machine can belong to the team instead of one person. Your agents act through the cua MCP server, and you choose what each one may do. See Connect your agent.