Function FullscreenLayout

src/components/FullscreenLayout.tsx:285–460

({
  scrollable,
  bottom,
  overlay,
  bottomFloat,
  modal,
  modalScrollRef,
  scrollRef,
  dividerYRef,
  hidePill = false,
  hideSticky = false,
  newMessageCount = 0,
  onPillClick,
}: Props)

 * so nothing can accidentally render outside it.
 */
export function FullscreenLayout({
  scrollable,
  bottom,
  overlay,
  bottomFloat,
  modal,
  modalScrollRef,
  scrollRef,
  dividerYRef,
  hidePill = false,
  hideSticky = false,
  newMessageCount = 0,
  onPillClick,
}: Props): React.ReactNode {
  const { rows: terminalRows, columns } = useTerminalSize();
  // Scroll-derived chrome state lives HERE, not in REPL. StickyTracker
  // writes via ScrollChromeContext; pillVisible subscribes directly to
  // ScrollBox. Both change rarely (pill flips once per threshold crossing,
  // sticky changes ~5-20×/transcript) — re-rendering FullscreenLayout on
  // those is fine; re-rendering the 6966-line REPL + its 22+ useAppState
  // selectors per-scroll-frame was not.
  const [stickyPrompt, setStickyPrompt] = useState<StickyPrompt | null>(null);
  const chromeCtx = useMemo(() => ({ setStickyPrompt }), []);
  // Boolean-quantized scroll subscription. Snapshot is "is viewport bottom
  // above the divider y?" — Object.is on a boolean → FullscreenLayout only
  // re-renders when the pill should actually flip, not per-frame.
  const subscribe = useCallback(
    (listener: () => void) => scrollRef?.current?.subscribe(listener) ?? (() => {}),
    [scrollRef],
  );
  const pillVisible = useSyncExternalStore(subscribe, () => {
    const s = scrollRef?.current;
    const dividerY = dividerYRef?.current;
    if (!s || dividerY == null) return false;
    return s.getScrollTop() + s.getPendingDelta() + s.getViewportHeight() < dividerY;
  });
  // Wire up hyperlink click handling — in fullscreen mode, mouse tracking
  // intercepts clicks before the terminal can open OSC 8 links natively.
  useLayoutEffect(() => {
    if (!isFullscreenEnvEnabled()) return;
    const ink = instances.get(process.stdout);
    if (!ink) return;
    ink.onHyperlinkClick = url => {
      // Most OSC 8 links emitted by Claude Code are file:// URLs from
      // FilePathLink (FileEdit/FileWrite/FileRead tool output). openBrowser
      // rejects non-http(s) protocols — route file: to openPath instead.
      if (url.startsWith('file:')) {
        try {
          void openPath(fileURLToPath(url));
        } catch {
          // Malformed file: URLs (e.g. file://host/path from plain-text
          // detection) cause fileURLToPath to throw — ignore silently.
        }
      } else {
        void openBrowser(url);
      }
    };
    return () => {