{#
  Lazy chunk placeholder contract:
  - id="document-chunk-N" identifies the frame as a document chunk.
  - class="document-chunk-placeholder" marks an unloaded placeholder.
  - loading="lazy" lets Turbo defer the fragment request.
  - src points to the server endpoint that returns this chunk's content.
  - data-node-mids maps every semantic node, including nodes
    omitted from TOC, to the frame that can load it.

  - node.css uses the placeholder class to reserve approximate
    scroll space until Turbo loads the chunk content.
  - toc_chunk_navigation.js observes placeholders by this class,
    validates the document-chunk-* id, eagerly preloads them near
    the viewport, and removes the class on turbo:frame-load.
#}
<turbo-frame
  id="document-chunk-{{ chunk.index }}"
  class="document-chunk-placeholder"
  loading="lazy"
  src="/fragments/document/{{ view_object.document.reserved_mid }}/chunk?from_node={{ chunk.first_node_mid }}&amp;count={{ chunk.size }}&amp;chunk={{ chunk.index }}"
  style="--document-chunk-size: {{ chunk.size }};"
  data-node-mids="{{ chunk.node_mids | join(' ') }}"
  data-testid="document-chunk-placeholder"
></turbo-frame>