This sounds like a pre-authz flight with prompt=none to attempt silent authentication.
1. First we construct an authz redirect with prompt=none, redirect the user to the OP, then they redirect the user back with: A. a code value, all good, B. one of the error keys specified in the spec, then construct an authz redirect without that prompt and re-redirect the user back to the OP, etc etc 2. we can complete Auth Code Flow.
This sounds like a pre-authz flight with prompt=none to attempt silent authentication first, then fall back to standard, prompted login otherwise.
1. First we construct an authz redirect with prompt=none, redirect the user to the OP, then they redirect the user back with: A. a code value, all good, B. one of the error keys specified in the spec, then construct an authz redirect without that prompt and re-redirect the user back to the OP, etc etc 2. we can complete Auth Code Flow.