# 0009: The workspace uses responsive self-contained vertical panels

Status: accepted for the native vertical slice.

The workspace shows one vertical panel in compact windows, three at normal
desktop widths, and five when at least 2800 px remains after the sidebar. A
3440 px ultrawide therefore presents five panels. A sliding window over the six
comparison panes always keeps the selected pane visible.

This is not a return to the original 2×3 dashboard and it is not one shared
20/60/20 frame sliced only through the middle. Every panel receives the full
workspace height and independently contains its own 20% context region, 60%
terminal/work surface, and 20% decision shelf. Only the selected panel owns
keyboard input. Clicking a panel selects it. Pane processes and output continue
independently of selection.

Terminal geometry is computed from the width of one panel and the height of its
middle 60% region, including gaps and content insets. The selected real PTY is
resized through the runtime actor when the responsive panel count or window
bounds change. On the 3440×1440 reference display the current fixed-cell spike
derives approximately 71 columns by 42 rows per panel.

The first actor slice still owns one real PTY and five deterministic comparison
surfaces. Promoting the runtime boundary from one actor to a pane-indexed session
registry is required before all five visible terminal panels can own independent
real processes.