we are planning on extending the UI of AEM, especially in the XML Documentation area.
We want to show additional UI elements in the sidebar.
Can you please let me know, which APIs / Extension Points exist to achieve this?
"side panel in web-editor of XML Documentation?" -> Yes
The sidebar of webeditor is not extendible without reloading the DOM, i.e. it does not have an extension point to add another tab without overwriting the implementation of existing tabs. However, in future releases, the side panels will too become customizable/extendible.
But there are options available to add features to the webeditor toolbar, one of the approaches is described in this article.
Can you share more details on the type of feature you are trying to add? I may validate if there is another way to do that.