Soft logout: Add a device_id query parameter on login fallback page

[manuroe]

In case of soft logout, we want to be able to log in back using the same device id. That means the fallback page must pass it for us in their login requests.

The proposal is a query param:

https://domain/fallback/page/?device_id=[DEVICEID]

Note: Riot mobile clients use the fallback page for SSO auth.

[clokep]

Reading back through some of the spec it seems that there are two ways to use SSO for login:

1. Go via the SSO Client login process, which ends up generating a login token which the client then uses to complete login via the normal /login endpoint.
2. Use the login fallback, which calls window.onLogin when it is done (so it seems to go through the whole login process itself).

I wanted to confirm / be a bit more specific that we're talking about the second option here -- a request is being made to /_matrix/static/client/login/.

If so, it seems that this would require some specification work to include the device ID.

[clokep]

And I guess the follow-up to this, are there any other parameters we would want to provide while doing this?

[clokep]

From some conversation it seems:

• This is about the /_matrix/static/client/login/ endpoint
• It was recommended to have this take a query parameter to feed into the login process.

To I think that answers my questions above.

[clokep]

Spec PR: matrix-org/matrix-spec-proposals#2604