Wraps + heights are column-dependent, so a width change must remeasure
every row and the renderer must repaint the full viewport.
- Key virtualRows on cols so React remounts wrapped rows on resize.
- Snap back to bottom after sticky-mode resize once React rerenders.
- Reserve a scrollbar + gap column in transcriptBodyWidth (non-termux).
- Full repaint on any viewport height change (was: shrink-only).
- ScrollBox scrollHeight uses deepest child bottom so sticky-bottom
math can reach the real final rendered row after reflow.
- DECSTBM fast-path now requires full container rect match.
Keep the resize delta below the virtual history scroll quantum so the regression test specifically depends on viewport height entering the snapshot key.
Notify scroll subscribers when ScrollBox viewport bounds change and key virtual-history updates on viewport height so resize/keyboard changes remount the tail rows instead of leaving stale spacers visible.
