composer require meteko/lowercase-pathsegment
Via the signal/slot nodePropertychanged this package make sure the pathSegment (used for routing) is always lowercase.
It's also possible to make a client side validation "version" of this.
By changing the regular expression validation for Neos.Neos:Document to regularExpression: '/^[a-z0-9\-]+$' (removing the /i) you make it case-sensible.
This will make it impossible so Apply until there is no uppercase characters in the field (and therefore, passing the validation)
Free support in the Neos Slack channel and bug/features via the Issues and Merge request feature ohere on Github!
Thanks to danish scout organization Frivilligt Drenge- Og Pige-Forbund, FDF for sponsoring this work and releasing it, for you to use free of charge!