A workspace is where one piece of work lives — attach the repositories it touches, any Domains with relevant background, and every conversation thread you start from it.
Activating a workspace checks out its own isolated copy of each attached repository, so whatever an agent does there never touches your main checkout until you're ready for it to.
Inside a workspace, five tabs cover everything: Overview for its basic setup, Threads for every conversation you've had, History for a running diff of everything changed so far (see Diffs, history, and editing files directly), Files for browsing and editing directly, and Settings for the finer points — nesting under a parent workspace (see Organizing bigger projects with phases), sharing another workspace's checkout, and more.
Opening a thread and sending a message starts a live conversation. You'll see the response stream in as it's generated, with any resulting code change shown right there as a diff.