issueNumber: MDL-88949
notes:
  core_courseformat:
    - message: >
        The course index tree semantics for subsections have moved from the
        delegated section wrapper to the activity that delegates it.


        * The `li[role="treeitem"]` in `core_courseformat/local/courseindex/cm`
        should add the following attributes when the activity has a delegated
        section:
          * `aria-owns`, set to the id of that section's collapsible content, `courseindexcollapse{{number}}`
          * `aria-labelledby`, set to the id of that section's title element, `courseindexsection{{number}}-title`
          * `aria-expanded`, set to `false` when the section's `indexcollapsed` is set and `true` otherwise
        * In `core_courseformat/local/courseindex/section`, `role="treeitem"`
        and those same three attributes should no longer be set when the section
        is delegated, and the section title element needs
        `id="courseindexsection{{number}}-title"` so the tree item can reference
        it.


        Note that the `core_courseformat/local/courseindex/section` JS keeps
        `aria-expanded` up to date by writing to the closest `[role="treeitem"]`
        ancestor, so the element carrying the role is the one that receives the
        state. Plugins overriding either template should update both, as the two
        are no longer independent.
      type: changed