The size preference is a ceiling, not an absolute: narrow panes (splits, the
side panel) now shrink the rendered size until a classic 80-column grid
fits, down to a legibility floor, and widening slides it back up to the
preference. The measurement lives in fit(), so pane drags, splits, and
window resizes all pass through it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>