Registered MIME types are ignored

Some apps register their own MIME types or act as a handler to open certain file types. For example Draw.io can be configured to open XML files or you can add ".drawio" as custom MIME type in /config/mimetypemapping.json (also see https://github.com/pawelrojek/nextcloud-drawio).

Within the file manager this works fine - when clicking an XML file (.xml) or a file with the extension .drawio Draw.io will start and open the file.

However - when I try the same with a file which is on top of the file list as "recommendation" or with an entry in the "recommendet files" box in the dashboard, XML files are always handled as text file and .drawio as unknown type, so only the file manager is opened with the file selected.

What is missing to make this work? Is this a bug in the recommendations app?

Start with the recommendations shown at the top of the file list and in the dashboard, then compare their handling with the file manager behavior described in the issue. Check /config/mimetypemapping.json for the registered XML and .drawio types. Done means recommended files invoke the registered handler instead of treating XML as text or opening the file manager.