I see, but the first example option having no code still makes it harder to translate and show the user, so my vote is for the option with a code and message in the json.

Message straight on the body is the worst possible response for an error here, it is bad design to straight up show the error from the back end to the user, usually it needs translation and/or adaptation due to message size on the front-end to show properly, and applying those on top of a message will make it stop working as soon as anyone in the backend decide to change a dot or comma anywhere. It is a bad idea to let the backend make direct impact in the front when you can because backend devs won’t even know what impact they are causing until later in testing and it will be harder to trace back and fix.

IMO you need at least a json with code and message, the front will ignore the message for everything but testing and use the code to match a translation file that will get the proper message, making it easy to translate and change as needed without having to rebuild the whole backend along with front changes. You may also have an extra parameter there in some cases when you want to return where more specifically the error occurred or an array of errors. Status usually not needed as you can get those from the http code itself.

Unless i misunderstood, I believe the point of this post wasn’t talking about defederating, it is asking about protecting the users data from Meta if federation happen, and for that point it is what I said, his data is as protected as before, federated or not, Meta won’t get access to any extra data from being federated than it already has access to now.

Defederating is another entire discussion that is really up to the instance admin, self hosting is the only way to really guarantee anything if you want that much deep control of your data and fediverse experience.

From what I understand about the fediverse, everything that Meta already knows about you and your content is going to remain the same. Federated or not, they will only have access to info you make public, and how much that is is entirely up to your instance. Even if Meta never wanted to join and federate with others, they could still scrape the same info and use as they see fit for training AI, duplicating posts or whatever.

So basically you don’t have to do anything, Meta cannot demand any extra data from you that your instance owner does not want to share. If you are worried your instance owner might do some deal with Meta for your data, then you can better control that with self hosting.