Questione giuridica chiave
Whether the administrative-law appeal was admissible, including the request for a declaration of nullity of the cantonal letter.
Decisione estratta
The appeal was admissible in principle because the appellant could invoke a statutory and Convention-based entitlement to renewal, but the request to declare the first letter null was inadmissible.
Motivazione estratta
A residence-permit renewal refusal can be a challengeable formative decision. However, due to the devolutive effect of the appeal, the separate nullity request concerning the preliminary letter could not be examined.