- Split panes by dragging a tab to a pane edge (left/right/up/down zones
with a drop overlay) or into the center to merge; the toolbar split
buttons are gone (split-pane.tsx, state.ts moveTabToEdge/insertLeafAt).
- The header close button is now a collapse button; the expand button on
the right edge stays visible whenever the panel is collapsed, so the
sidebar can always be reopened (Sidebar.tsx, locales collapse/expand).
- Styles now follow the DSH web-styling rules exactly: --dsw-alias-*
semantic colors (state-error/warn tokens), --dsw-font-* typography roles
(size + line-height paired), --dsw-shadow-lv* elevation, no color
literals or static palette values (sidebar.module.css).
- Tests: +3 for moveTabToEdge (edge split, center merge, self reorder).
Menghuan1918
58b4bd71ba