CuaCua

Child Spaces

Let a Space make Spaces of its own: an agent inside it creates, uses and deletes children, without your account and without reaching anything else.

A Space can make Spaces of its own. An agent working inside it can fork 32 copies to run a benchmark, start a fresh machine to test a build, or try a change on a clean desktop, then delete them. These are its children: they belong to it, and it can reach nothing else.

Child Spaces is an experiment and is off until you turn it on with cua experiments enable child-spaces. While it is off, no Space can make children and the commands on this page stay out of --help. An agent run turns this on for its Space by itself once the experiment is on. For any other Space you turn it on yourself.

Turn it on#

cua spaces create linux --name studio --children
cua spaces children studio on
cua spaces children studio off

Off ends the Space's right to make children at once. Children it already made keep running until they are deleted or their time runs out.

Inside the Space#

Nothing to set up. The same commands and tools work, and every Space they make is a child of this one:

cua spaces create linux --name worker
cua spaces ls
cua sb exec worker -- make test
cua spaces rm worker

An agent gets the same as tools in its Space's own MCP server: create_space, fork_space, list_spaces, space_bash, stop_space, start_space and delete_space. Code that uses the SDK (cua.auto()) works too.

What a child gets#

  • Where. A child runs on the same computer as its parent unless it asks for --on auto (the least-loaded of your computers and linked clouds), --on host:<name> or a linked cloud (--on aws). This computer's cua daemon creates it with your own sign-in and cloud links. The Space asking never holds them. A Windows child needs a machine with virtualization: a Windows PC of yours, or a cloud host that offers it. Hetzner Cloud servers can't run VMs, so Windows children don't go there.
  • No wider network. It keeps its parent's egress rules. A request for wider ones is refused.
  • Cost counted. A child in a linked cloud counts what it adds per hour against its tree's budget and your account's cloud budget. The stricter one wins.
  • No longer life. It ends when its parent would, and after 4 hours at most unless you give it longer.
  • Limited depth. A child may make children of its own, two levels below the Space you made. Deeper requests are refused.

A budget per tree#

Each tree has a budget: how many child Spaces, vCPUs and memory its children may hold at once, and what they may cost. The defaults are 16 Spaces, 16 vCPUs, 32 GiB and $2 an hour, so a runaway loop stays cheap. A child that does not fit is refused with what is left, in words an agent can act on. Creates in flight reserve their share first, so two at once can't pass the budget together.

cua spaces budget studio
cua spaces budget studio --spaces 32 --cpus 64 --memory 131072
cua spaces budget studio --clear

Inside a Space, cua spaces budget shows its own tree's budget and use. Only you can change it.

What a Space can't do#

The channel a Space uses answers for its own children and nothing else.

  • Other Spaces. Your other Spaces, its parent and its siblings look the same as a Space that does not exist.
  • Your account. It holds no account sign-in, cloud link or key, so it can't share, connect clouds or reach your other computers.
  • A copied capability. The capability it holds works only on its own channel. A copy taken from a snapshot, a fork or another Space is refused.

The channel is not a network port. The Space's own cua-spacesd keeps it on the Space's loopback and hands each connection to this computer's cua daemon over the connection the daemon opened. The daemon knows which Space is asking from the connection, never from what the Space says.