· Workspace
Pane groups, and focusing one pane to fill the space
Named groups of panes, switchable from the command palette, plus a focus mode that gives one pane the whole space and gives it back.
A space accumulates layouts. The arrangement for reviewing a diff is not the arrangement for debugging a terminal, and rebuilding one from the other by hand is the work the pane grammar exists to avoid.
Groups are named layouts within a space. Existing layouts migrate into a single Main group, so nothing has to be rebuilt.
Focus fills the space with one pane and restores the arrangement when you leave. Splitting equalises every pane in that split, so three sessions side by side are three equal columns, not 50/25/25. Double-clicking a divider restores a split to its original sizes.