---
title: Machines
description: The agent's own computer in the cloud, which sleeps when the work is done and wakes when you send a message.
---

Every Session runs on a Machine: the agent's own computer in the cloud, with
your repository, your tools and a browser on it. Because the agent works there
instead of on your laptop, it can install what it needs, run your app and tests,
and keep going after you close your laptop. You don't manage the Machine:
Polaris starts it, puts it to sleep when the agent is done, and wakes it when
you send a message.

![The end of a Session transcript with the notice Machine went to sleep, awake for 22m, and Send a message to wake it up, above the composer.](/docs/screenshots/machines.webp)

## What's on a Machine

- Your repository, on the branch you started from, for the agent to edit,
  commit and push.
- The tools and dependencies that [Workspace setup](/docs/workspace-setup) installs,
  plus anything the agent installs along the way.
- A [terminal](/docs/terminal), a [browser and a desktop](/docs/browser-and-desktop)
  you can open beside the Session, and its [files](/docs/files).
- The apps the agent runs, which you can open in a [Preview](/docs/previews).

A Machine's files, changes and Previews are visible to the people who can see
its Sessions.

## Choose its CPU, memory and disk

![The Machine picker at the top right of the Start composer, open with Standard (4 CPU, 16 GB, 128 GB disk), Large (8 CPU, 32 GB), Large memory (8 CPU, 64 GB) and Custom.](/docs/screenshots/machines-resources.webp)

When Polaris can change a Machine's resources, **Start** shows the Machine at
the top right of the composer: **Standard**, or the Project's default. Select it to choose a preset, each listed with its CPU,
memory and disk, or **Custom…** to set them yourself. Custom offers only what's
available: CPU and disk show as text when they can't change, and memory is a
slider. The Machine keeps these resources until you [change them](#change-its-cpu-and-memory).

The memory you choose is the most the Machine can use. It gets memory as it
needs it, so a tool on the Machine such as `free` can show less while it's idle.

Each Project can then set a default in [Project settings](/docs/projects#what-a-project-sets).
When the Project's default isn't available, Start begins at **Standard**.

## Change its CPU and memory

![Resize Machine open under the Session's ⋯ menu: CPU 4 or 8, a memory slider from 8 to 64 GB at 16 GB, the 128 GB disk, and Resize.](/docs/screenshots/machines-resize.webp)

Select **Resize Machine** in the Session's **⋯** menu at the top right, choose
**CPU** and move **Memory**, then select **Resize**. The Machine usually keeps
running, with its Sessions, programs and files. If it has to restart to take
the change, it says so: running programs stop and files are kept.

- When the Machine is asleep, a change of CPU or more memory applies when it
  wakes. To lower its memory, select **Wake machine** first.
- Memory can go down only to a little more than the Machine is using. The
  Machine lowers it as far as it can and shows the memory it reached; if it
  can't lower it at all, it keeps its memory and says so.
- Disk stays as it is for now.
- The agent can ask for more CPU or memory when its work needs it, such as tests
  that run out of memory. A question above the composer shows the resources it
  asks for and why. Select **Resize** to resize the Machine as you would from
  the menu, or **Not now**. The agent never resizes the Machine itself.

![The agent's request above the composer: Resize this Machine to 8 CPU · 32 GB?, the agent's reason, It has 4 CPU · 16 GB now, and Not now and Resize.](/docs/screenshots/machines-resize-request.webp)

The Machine keeps its new resources when it sleeps and wakes, and new Sessions
an agent starts from it get the same.

## Sleep and wake

When the agent has nothing left to do, its Machine goes to sleep: about five
minutes after the agent finishes, or about 15 minutes after your last click,
scroll or keystroke while you have the Session open. Clicking or typing in your
app in the Session's **Preview** counts too, but scrolling there doesn't, and a
Preview open in its own browser tab doesn't count at all. To keep it awake for
a while without using it, see [Keep it running](/docs/previews#keep-it-running). The
transcript ends with **Machine went to sleep**.

To wake it, send a message; the agent picks up where it left off. Opening one
of its [Previews](/docs/previews) in the Session wakes it too. In a panel that needs
the Machine, such as **Files** or **Terminal**, you can also select **Wake
machine**. A [check-in](/docs/check-ins) the agent scheduled wakes it on its own.

## What survives sleep

Your files, including uncommitted changes, the tools installed on the Machine
and the whole conversation are still there when it wakes. Programs the agent
left running, such as a dev server, can stop. To have your app come back after
a wake, see [Keep it running](/docs/previews#keep-it-running).

## Keep a long job running

The Machine stays awake while the agent works and while it waits on a command.
For a job that should keep running after the agent replies, such as a long test
suite or a data import, ask the agent to keep the Machine awake until it
finishes.

Archiving every Session on a Machine puts it to sleep, even if a job is still
running or someone [kept it awake from a Preview](/docs/previews#keep-it-running).

## Run several Sessions

Every Session you start gets its own Machine, so tasks run side by side without
touching each other's files. Start as many as you need. [Subagents](/docs/subagents)
are the exception: they work on the same Machine as the agent that started
them. To list every Session on one Machine, select **List options** → **Filter**
→ **Machine** in the sidebar.

## Delete a Machine

When you no longer need a Session's work, select **Delete machine…** from its
row in the sidebar or the **Session actions** menu above the transcript, then
confirm. Deleting is permanent: the Machine and everything on it are gone, and
you lose access to every Session on it. Ask the agent to push anything you want
to keep first.

## If it doesn't work

- **Machine is asleep** in a panel: select **Wake machine**, or send a message.
- **Machine is unavailable** or **This machine is no longer available.**:
  select **Go to Start** and start a new Session from the same repository. Work
  the agent pushed is safe on GitHub.
- **An agent is still working on this machine.** when you delete: wait for it
  to finish, or stop it, then delete.
- For anything else, see [Troubleshooting](/docs/troubleshooting).