Correct HATEOAS response when creating a user account - json

Question

I have a REST api written in node which uses HATEOAS. The user is required to have an account before they can access the bulk of it.
They register an account with login details, then login to obtain an access token, and then use that token in order to access any endpoints that aren't register or login.
Issuing a get to the root responds with a directory with available actions.
Q: What is the correct response from register, to tell the client what it can do next (i.e. login)?
register technically creates a new resource on the server so a 201 CREATED and a Location header would seem appopriate. However the login reference isn't the location of the newly created resource.
Should I return 201 Created with a Location pointing to the newly created user (e.g. /myaccount or /users/{id} and then include a login link in the response body?
{
_links: {
self: { href: "what goes here?" },
x:login: { href: "/login" }
}
}
Do I not tell the client at all, and require them to do a get on the application root in order to fetch a list of available endpoints. This should include login anyway. Assuming the client had to do that in the first place to get the register link it should already have login.
Expecting the client already to already have the login link feels uncomfortable as it relies on an assumption of the client's prior activity.
Requiring the client to issue another request to the root directory after registering seems mean, inefficient and unnecessary. If the client has just created a resource it seems only fair that the server should respond with what it can do with it next.

Answer 1

I like to have my api's act no differently than a webpage. If you want the UX of your application to be the user is taken to login after they register, then 302 them from a successful register to the login resource. And upon successful login, 302 to them to the appropriate destination (IE, if they tried to access something with no token, then take them to login, with a destination of the original requested resource). That's and important part to your #3. Having a link off the root that leads to login, but you need to protect all the other links such that they indicate (and link to) a login being required to access the resource. The client app should expect to get this login required response at any time as tokens can (and do) expire at any time.
Following on this, it might make sense to do the JWT as a cookie instead of as an Authorization Header, it would make it a bit easier for the client (they just have to setup a cookie jar)..if the client is say a native mobile app that maintains a single connection setup. If it's server to server, then auth header makes sense. I'd go about supporting both to cover both scenarios.
Continuing on the idea of thinking of the api as a web site. Why have them login after registration at all? Why not have the registering of an account end up with the login token being sent? they just set their user/pass, why make them enter it again? I realize with some more exotic architectures the register service can not perform the login action (perhaps it doesn't have the private key to sign the token), but if it is possible i'd consider it.
If you really want to stick to the 201 header (which is fine, just make sure the docs of your register relationship indicate that), then option 2 is the closest in my opinion. A location header to the URL of the account just created a 201 is pretty standard for creating a user. But, i'd not return what you've supposed there. You're kind of returning a account-created resource (the thing with the login link), but do you really need this custom resource? If you want to give some messaging back to the client (like "Account Created") in that resource then absolutely yes, but you could also just give them back the root resource.
tl;dr; Decide what you want your UX to be and then make your API implement your UX.