Child ordering route renders nested books as a flat list
>>> [!note] Migrated issue
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<!-- Migrated from issue #3538743. -->
Reported by: [codebymikey](https://www.drupal.org/user/3573206)
Related to !116 !115 !107 !106
>>>
<h3 id="summary-problem-motivation">Problem/Motivation</h3>
<p>On the <code>/node/{node}/child-ordering</code> route, child book nodes are rendered as a flat list which can be very confusing for users.</p>
<p>The "Books" route always keeps the indentation relative to how it is in the book.</p>
<p>The child re-ordering link needs to render the indentations relative to the node it's re-ordering from.</p>
<p>Attached images for reference.</p>
<h4 id="summary-steps-reproduce">Steps to reproduce</h4>
<p>1. Create a nested book at least 3 levels deep.<br>
2. On the 3rd level node, create 2 more child nodes.<br>
3. On one of the child nodes, add another child node.</p>
<p>All the books will be shown as a flat list.</p>
<h3 id="summary-proposed-resolution">Proposed resolution</h3>
<p>Take the parent node's depth into account, so that the indentation is relative to it for the child order page.</p>
<p>The "Books" list will be left as is, unless the change in rendering is desired.</p>
<p>Before:<br>
<img src="https://www.drupal.org/files/issues/2025-07-30/book-child-order.jpg" alt="previous indentation behaviour"><br>
After:<br>
<img src="https://www.drupal.org/files/issues/2025-07-30/book-child-order-after.jpg" alt="indentation behaviour afterwards"></p>
<h3 id="summary-remaining-tasks">Remaining tasks</h3>
<p><del>Provide MR.</del></p>
<h3 id="summary-ui-changes">User interface changes</h3>
<p>Indentations for nested books are actually rendered.</p>
<h3 id="summary-api-changes">API changes</h3>
<p>N/A.</p>
<h3 id="summary-data-model-changes">Data model changes</h3>
<p>N/A</p>
issue