The fix for the real preset bug: previously, presetSingle/2H/3H/2V/2×2
appeared to preserve panes (we copied id/distro/cwd/label/broadcast
into the preset's slots), but React's reconciliation tore down every
LeafPane and re-mounted it because the tree structure changed —
killing all PTYs and spawning fresh shells. The "preservation" was
data-only; the React components didn't survive.
Solution: stop rendering the Pane → SplitNode → LeafPane recursion.
Walk the tree to produce a FLAT layout of `{leaf, box}` entries (each
box is top/left/width/height as fractions 0–1). Render all leaves as
siblings of a relative-positioned container, each absolutely
positioned by its box. Key each one by leaf.id — React preserves the
component (and its XtermPane → PTY) across any tree reshape; only the
inline style changes.
Gutters render as separate sibling overlays at the split boundaries,
each with its own pointer handlers. Dragging mutates the split's
ratio via `updateSplitRatio(tree, splitId, r)`; the layout
recomputes; leaf boxes change; nothing remounts.
Now: clicking 2×2 on 4 stacked panes keeps all 4 shells alive and
just rearranges them into the grid. Same for any preset that doesn't
overflow.
Side benefit: removed the recursive Pane.tsx + SplitNode.tsx + their
CSS. The render path is now straightforward, no recursion, easier to
reason about.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
