Standard way to add/change WebID at the Identity Provider

[woutermont]

Neither OAuth2.0, nor OpenID Connect (nor, currently, Solid-OIDC), specifies how to let a user/subject add or change claims — and, by extension, their identifying information (e.g. sub and webid claims). Making the jump from local to global information, however, Solid-OIDC would i.m.o. benefit from standardizing this, at least for those claims that are accepted identifiers within the Solid ecosystem (*).

Specific use-cases that come to mind are:

• users with accounts at multiple Identity Providers for different WebIDs, wishing to merge the information on both;
• users with a single WebID pointing to a single Identity Provider who, on creation of a second WebID, want to keep identifying using the same Identity Provider; and
• users with a self-minted WebID, wanting to add it as a claim to a (new or existing) Identity Provider.

While not necessarily about account registration, this seems closely linked to solid/solid-oidc#77 (proposing to incorporate the OpenID Connect Create Prompt draft).

Very interested to hear your thoughts on this, whether you think this is desirable, and how you think this could best be achieved.

(*) I'm writing this about WebIDs, but this holds more generally for all kinds of "solid claims", cf. https://github.com/solid/solid-oidc/issues/26.