Computers, devices and Spaces
The difference between a signed-in device, a machine, its shared desktop and a sandbox Space, and why one computer can show up twice.
One computer can be both a device you connect from and a machine that runs Spaces. These names describe different roles:
| Name | What it is | Where you see or use it |
|---|---|---|
| Signed-in device | A computer enrolled to reach your account's machines, once, with a second factor. Signing in does not make it a host. | Settings > Devices or cua devices ls, with an id such as dev_…. |
| Machine | A computer set up with Add a computer or cua host setup to share its desktop, provide Spaces, or both. | The Computers page. When Provide Spaces is on, --on host:<machine-id> creates new Spaces on it. |
| The machine's shared desktop | The computer's own screen, input, shell and files as a Space, while Share this desktop is on. It is not a sandbox. | relay:<machine-id> for a computer set up on the relay. A direct host (set up with --direct, no relay record) is its own direct:<host:port> Space, added with cua spaces add <host:port> --host. For a relay computer, its row on Computers says Desktop shared, or Desktop · 2 Spaces when it also runs Spaces; the desktop is not counted among them. |
| Sandbox Space | A container, VM or microVM created for work, on this computer or on a machine that provides Spaces. See Space kinds. | local:<name> on this computer. On a relay machine that provides Spaces it has its own relay: id, with host naming the computer that runs it. On a direct host (set up with --direct, no relay) it has a direct:<host:port> id, whether created on that host or added by address. |
Share this desktop and Provide Spaces are separate settings. Hosting alone never enrolls a computer as a device: a computer that only hosts joins with its own token and can't reach your other computers.
Why one computer can show up twice#
A computer set up with cua host setup on the relay has a machine record. (A direct host, set up with --direct and no relay, has no relay record and is listed from your laptop's own host list.) Signing in on
that computer, in the app or with cua auth login, also gives it a device
record. The relay keeps the two apart and doesn't link them: they are one
computer in two roles, not two computers.
The Computers page joins them into one row when it can match them safely, for example by the same id or matching names. If the match is unclear, such as two Macs with the same name, they stay as separate rows. A row that is only a device is not a host, so Run on in New Space never offers it.
See Add a computer for the two settings and How Spaces works for Space ids.