I’m aware that using /USER_ID/feed on a API call, you can write to this user ID’s wall.
My app manages to get that ID from a database and, given this user has already accepted the app, it writes on this user’s wall normally, while they’re offline.
But understand: if you try to do that while offline, it’ll post as the USER_ID.
What happens is: while you’re logged in, if yout try to use /ID/feed, and the ID isn’t yourself, it’ll try to post on that user’s wall.
If you, however, aren’t logged in, it’ll try to post AS that user ID, and, since the user won’t have your app accepted, it’ll fail (or if that user has your app accepted, it’ll post as if it were him).
I wonder if there is no “to” or “target_id” field we can fill in?
I have no idea how to, while offline, make a user post to another user’s wall.
Ok, so what I was doing wrong was: I wasn’t using the original user’s access token. Since this is how Facebook identifies who is posting, now it works properly.