Pull Request resolves # .

• I read the Generative AI policy and my contribution is either not created with the help of AI or is compatible with the policy and GNU/GPL 2 or later.

Summary of Changes

ARIA defines:

aria-posinset → position in the set
aria-setsize → total number of items

Both are human-relevant, not zero-based programming indexes.

So valid output should be:

Testing Instructions

In media manager create some folders and then check the values of the a links of each tree item (directory name)

It should be telling you which item (posinset) the link is in the set (setsize)

This is an npm change so you either need to npm ci or use a pre-built package

Actual result BEFORE applying this Pull Request

the links are zero-based so the first link is
<a role="treeitem" aria-level="2" aria-setsize="6" aria-posinset="0" tabindex="-1"><span class="item-icon"><span class="icon-folder"></span></span><span class="item-name">banners</span></a>

and the last one will also have a posinset value of 1 less than the setsize
<a role="treeitem" aria-level="2" aria-setsize="6" aria-posinset="5" tabindex="-1"><span class="item-icon"><span class="icon-folder"></span></span><span class="item-name">banners</span></a>

Expected result AFTER applying this Pull Request

the posinset correctly starts at 1 and ends with the value=setsize
<a role="treeitem" aria-level="2" aria-setsize="6" aria-posinset="1" tabindex="-1"><span class="item-icon"><span class="icon-folder"></span></span><span class="item-name">banners</span></a>

<a role="treeitem" aria-level="2" aria-setsize="6" aria-posinset="6" tabindex="-1"><span class="item-icon"><span class="icon-folder"></span></span><span class="item-name">banners</span></a>

it is debatable if we even need this as it wold normallyb only be used if the entire set is not displayed. But as we do already display the posinset it should at a minimum have the correct values

Link to documentations

Please select:

• Documentation link for guide.joomla.org:

• No documentation changes for guide.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed