Running a session
Start an agent on a task, watch it work, steer it, and review what it changed — all from the project workspace.
A session is one agent run in its own disposable sandbox. You describe a task, the agent works on a private branch, and you keep the result through review. This is the loop you'll use every day.
Start a session
Describe the task
Open a project and use the composer on the project home to describe what you want — the same way you'd brief a teammate. Be specific about the goal and any constraints; you can keep talking to the agent once it starts.
Press send and Machine boots a fresh sandbox for this session. The first boot takes a few seconds; you'll land in the session view as soon as it's running.
Pick a model (optional)
The model selector in the session header lets you choose which Claude model runs the agent — a faster one for quick edits, a more capable one for harder work. The default is a sensible balance; switch any time.
Work with the agent
The session view is a conversation. The agent narrates what it's doing, and you can reply at any point — answer a question, redirect it, add detail, or tell it to try something else. You don't have to wait for it to finish.
Alongside the conversation you have:
- Files — browse the sandbox's working copy as the agent edits it.
- Terminal — see the commands it runs and their output.
- Diff — review the exact changes it's proposing, file by file. A badge shows when there are pending changes to look at.
The agent works in a private, disposable copy of your project on its own branch. Nothing touches your real project until you review and merge — so let it run, experiment, and even make mistakes safely.
Steer the run
A few controls shape how the agent works:
- Context — add code context, knowledge files, or a system prompt for this session, so the agent has what it needs without you pasting it into chat.
- Session settings — choose which agents, skills, and tools are available for the run.
These live in the session's settings; set them up front for a big task, or adjust mid-run.
Keep, share, or revisit
When the agent finishes a piece of work it opens a change request — a summary plus the exact diff. That's your review gate; see Reviewing changes to merge it.
From the session's actions you can also:
- Pin a session you'll come back to.
- Rename it so it's easy to find later.
- Share a read-only replay link so a teammate can see exactly what happened — no edits, no account juggling.
- Export the transcript to download the conversation and changes.
The sandbox is thrown away when the session stops or goes idle. Only work the agent committed and pushed to its branch survives — and only a merged change request makes it part of your project. If in doubt, merge.
Next: Reviewing changes to land the work · Sessions concept for the model behind it.