KDL basics

A layout is a text file that describes an arrangement of panes and tabs. They're written in KDL, a small, readable config language. A layout is just nested pane and tab nodes, with a split_direction where you want to control how children divide the space.

layout {
    pane
    pane split_direction="vertical" {
        pane
        pane command="htop"
    }
}

Read that top to bottom: one pane, then a vertically-split region holding two panes, the second of which runs htop on load. A pane with a command starts that program instead of a bare shell. Tabs work the same way, one level up.

layout {
    tab split_direction="vertical" {
        pane
        pane
    }
    tab {
        pane
        pane
    }
}