A solution for respecting all page types in URL generation and adding a checkbox at page level to exclude this can be found at https://github.com/b13/masi

SlugHelper::resolveParentPageRecord is skipping the folder, the comment of the method says:

Fetch a parent page, but exclude spacers, recyclers and sys-folders and all doktypes > 200

I am not sure if this behavior is intended.

"Is it really necessary to exclude parent sysfolder pages from the automatic page slug creation?"
Well realURL did so. If we migrate a project from realURL we can not simply take the folders into the path!

At least there has to be a setting to enable it, OR Folders should not have slugs at all! Because they are not used but blocking pages from getting the path.

Contact[folder] -> Slug: /contact

Contact[page] -> Slug: /contact-1

The changes made in #18079 now lifted the restrictions in PageRepository that were present for all doktypes > 200.
This should also be lifted for SlugHelper::resolveParentPageRecord() that currently excludes any page >= 199.

• DOKTYPE_SPACER (199)
• DOKTYPE_SYSFOLDER (254)
• DOKTYPE_RECYCLER (255)

However I think it should be configurable for DOKTYPE_SYSFOLDER, if a sysfolder slug should be added to a child page or not. Currently, pages of doktype sysfolder even show the "slug" field, although it is not used...