Sleep, wake and reset

Every session runs on its own machine, and that machine sleeps when you’re away and wakes when it’s needed, with every file, package and running process as you left it. A turn never depends on your browser, so you can close the tab mid-task and come back to finished work. To copy a session’s machine into a new session instead, fork it. To start sessions from a ready-made machine, use a setup.

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What happens when I close the tab?

The turn keeps going. The agent runs on Alpha’s servers, not in your browser, so closing the tab, the window or the laptop doesn’t stop it. A turn can run for up to 48 hours (default), and a server restart on Alpha’s side doesn’t end it either. When you open the session again, Alpha replays the transcript and attaches you to the live stream, so you land on whatever the agent is doing now. If the agent stopped to ask you something, the session’s row in the sidebar shows a question-mark icon (labelled “Needs your input”), and the machine stays awake until you answer the question card.

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When does a machine go to sleep?

Once no Alpha page of yours has been visible for about 30 minutes, each of your sessions with nothing running goes to sleep. Visible means the selected tab of a window that isn’t minimised (on macOS and Windows, not fully covered by other windows either). It doesn’t need focus, and any Alpha page counts: a session, the home screen, Usage or Skills. While one is on screen, none of your machines sleep. Going to sleep saves a full copy of the machine’s memory and disk, then shuts the machine down. Nothing is discarded. Only work wakes a machine while you’re away. Background tabs, the Shell, preview links and viewers never do. A background tab reconnects often, and would otherwise undo every sleep. A visible window counts even with nobody at it, such as Alpha left open on a second monitor. Alpha can also put an idle session to sleep sooner while it moves machines between its servers, but never one that’s open in a visible tab.

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Wake a sleeping machine

You don’t need to do anything. When you come back, the session on screen wakes by itself. Other sessions wake when you open them, or when something needs their machine: a message, a file, the Shell or the Preview. The sidebar’s hover card shows “Machine asleep · wakes when you open it” until then. Waking takes a few seconds. If you send a message to a sleeping session, the working line under it says what Alpha is doing: While the machine wakes, every workspace tab that reads from it shows grey placeholder bars: file tabs, file viewers, decks, Preview, Shell, Database, GitHub, Agent and Evals. They fill in by themselves once the machine is up, with no error and nothing to retry. The Shell reconnects on its own and can fill in a few seconds after the others. Tabs that don’t read from the machine, such as Plan, Auth, Routines and Secrets, show at once. The transcript loads its newest two turns first, so a long session opens quickly. Scroll up, or click the Show earlier messages button above them (it shows how many, as in Show 12 earlier messages), to load older ones. The Preview can show the app before the machine is back. Alpha keeps a saved copy of the page and serves it while the machine wakes, with the line “The last saved copy of the app — the live page takes over on its own once the machine is back.” The live app replaces it without a reload. See Preview your app.

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What if a machine won’t wake?

Alpha never swaps a sleeping machine for a blank one behind your back. If it can’t bring the machine back, it tells you and keeps the saved copy, so you can try again. Each of these messages says “Nothing was discarded” or asks you to try again, and means exactly that. More fixes are in Troubleshooting and FAQ.

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Reset the session’s machine

A reset throws the session’s machine away, along with its saved copy, and gives the session a fresh one on its next message. It’s the fix for a machine that is broken beyond repair, or won’t wake after several tries. A session that has slept and woken dozens of times can also start to wake more slowly, and a reset clears that too. Only an admin can reset a machine. Ask your Alpha’s admin, and tell them which session it is. What a reset keeps: the transcript, the session’s settings, repositories, secrets and setup, and every app you published from it. Services such as the database start switched off on the new machine, and come back when you or the agent turn them on.

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What survives what

The session’s machine has 10 GB (default) of disk. Other limits are in Limits.

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Next steps