What is the expected behaviour on the Consumer Experience (CX) for closed accounts?
In the CX wireframes closed accounts are displayed in the "Accounts unavailable for sharing", however under a previous article "Expected API Behaviour for Closed Accounts" it states: "All APIs are in scope for closed accounts. However scheduled payments and direct debits APIs should return a 200 OK with an empty response. It would still be valid to allow ADRs to get the details on an account and any past transactions on the account even if it is closed. You're correct that the ADRs would use the BankingAccount::openStatus to deduce if the account is closed or not".
The API responses indicates closed accounts should be displayed in the "Accounts available to share" section of the CX.
Which path should a Data Holder (DH) follow?
It is true that closed accounts should be in the 'available' list if they are eligible. The CX Guidelines demonstrate how DHs could tend to the issue of accounts being eligible but unavailable for some reason; they do not suggest that closed accounts should be considered unavailable or ineligible by default. The use of a closed account in the CX Guidelines is purely illustrative.
The classic example considered for the unavailable account design pattern is a joint account that has not been made available for sharing, but there are other possible scenarios where a data holder could implement this design pattern to communicate that accounts are not displaying for other reasons.
The unavailable account item is an optional aspect of the CX Standards for the account selection step. The model was produced to be flexible enough to apply to a range of situations if required. How/if a DH implements this pattern is at the DH's discretion.