Add validation for referral type when permanently decanted from PRP-only housing

app/models/lettings_log.rb

@@ -381,6 +381,10 @@ class LettingsLog < Log
     referral == 1
   end
 
+  def is_from_prp_only_housing_register_or_waiting_list?
+    referral_type == 3
+  end
+
   def is_relet_to_temp_tenant?
     # 9: Re-let to tenant who occupied same property as temporary accommodation
     rsnvac == 9

app/models/validations/household_validations.rb

@@ -30,11 +30,16 @@ module Validations::HouseholdValidations
     end
     validate_other_field(record, 20, :reason, :reasonother)
 
-    if record.is_reason_permanently_decanted? && record.referral.present? && !record.is_internal_transfer?
+    if record.is_reason_permanently_decanted?
+      if record.referral_type.present? && !record.is_from_prp_only_housing_register_or_waiting_list?
+        record.errors.add :referral_type, I18n.t("validations.lettings.household.referral_type.leaving_last_settled_home.reason_permanently_decanted")
+      end
+
+      if record.referral.present? && !record.is_internal_transfer?
         record.errors.add :referral, I18n.t("validations.lettings.household.referral.leaving_last_settled_home.reason_permanently_decanted")
-      record.errors.add :referral_type, I18n.t("validations.lettings.household.referral.leaving_last_settled_home.reason_permanently_decanted")
         record.errors.add :reason, I18n.t("validations.lettings.household.reason.leaving_last_settled_home.not_internal_transfer")
       end
+    end
 
     return unless record.form.start_year_2024_or_later?
 

config/locales/validations/lettings/household.en.yml

@@ -107,3 +107,6 @@ en:
           la_general_needs:
             internal_transfer: "Answer cannot be internal transfer as it’s the same landlord on the tenancy agreement and the household had either a fixed-term or lifetime local authority general needs tenancy immediately before this letting."
 
+        referral_type:
+          leaving_last_settled_home:
+            reason_permanently_decanted: "Answer must be from a PRP-only housing register or waiting list (no local authority involvement) as the tenant was permanently decanted from another property owned by this landlord."