Enabling follow your nose when the application does not have or want a new data grant

When restricting data access by application as well as user, a user might want to follow a link to a resource that they have access to, but that the application does not - and does not wish to support.

An app developer would want confidence that if they support arbitrary links, SAI/Solid provides a consistent and acceptable user experience of handing over to another application.

If Alice follows her nose from a non-Solid app, Alice would also expect to be provided some kind of user interface

I believe this has implications for a spec, though it is not yet clear which.

Here are some options, mostly based on conversation at https://github.com/solid/data-interoperability-panel/issues/237

1. Just show a 401 error, as already spec-ed
2. Accessing resources on Solid storages MUST offer a user interface for the user.
   2a) Resources offer a default view of themselves
   2b) Minimal login, e.g., via FedCM
3. hand it off to an app with universal access, which the user's profile(?) MUST define
   3a) hand it off to AA
   3b) hand it off to a "launcher app", which is not the AA but does have universal access.
4. AA is registered at OS level as a handler, e.g. web share target
5. Apps shouldn't link to resources they don't support

Start by reviewing the options in this issue and the linked discussion at data-interoperability-panel#237. A useful outcome would be a resolved direction for handing users from unsupported applications to accessible resources, together with the affected specification requirements; no repository file or test is named.