Function editorHalfPage

packages/app-core/src/components/Editor.tsx:157–173

* Clamped half-page scroll for the editor, bound to Ctrl+D / Ctrl+U. * * Replaces CodeMirror-Vim's built-in ` `/` ` (`moveByScroll`), which * derives its scroll target from the cursor's pixel coordinates. With live- * preview decorations and folded headings shifting block heights, that m

(view: EditorView | undefined, forward: boolean)

 * wrap. Mirrors the clamped preview scroll (`scrollPreviewBy`) in VimNav.
 */
function editorHalfPage(view: EditorView | undefined, forward: boolean): void {
  if (!view) return
  const scroller = view.scrollDOM
  const half = Math.max(1, Math.round(scroller.clientHeight / 2))
  const lineHeight = view.defaultLineHeight || 18
  const steps = Math.max(1, Math.round(half / lineHeight))
  let range = view.state.selection.main
  for (let i = 0; i < steps; i++) {
    const next = view.moveVertically(range, forward)
    if (next.head === range.head) break // reached the first/last line — stop, never wrap
    range = next
  }
  const maxTop = Math.max(0, scroller.scrollHeight - scroller.clientHeight)
  const nextTop = Math.max(0, Math.min(maxTop, scroller.scrollTop + (forward ? half : -half)))
  view.dispatch({ selection: { anchor: range.head } })
  scroller.scrollTop = nextTop
}

function syncVimKeymaps(overrides: KeymapOverrides): void {
  const mappings: Array<{ id: KeymapId; action: string; bindings: string[] }> = [