Function toggleExpand

frontend/app/treeview/treeview.tsx:337–356

(id: string)

    };

    const toggleExpand = (id: string) => {
        const node = nodesById.get(id);
        if (node == null || !node.isDirectory || node.notfound || node.staterror) {
            return;
        }
        const expanded = expandedIds.has(id);
        if (!expanded) {
            loadChildren(id);
        }
        setExpandedIds((prev) => {
            const next = new Set(prev);
            if (expanded) {
                next.delete(id);
            } else {
                next.add(id);
            }
            return next;
        });
        scrollToId(id);
    };

    const selectVisibleNodeAt = (index: number) => {
        if (index < 0 || index >= visibleRows.length) {