feat: route la question when not inferred for supported housing

app/models/derived_variables/lettings_log_variables.rb

@@ -176,11 +176,15 @@ module DerivedVariables::LettingsLogVariables
 
     if !form.start_year_2026_or_later? && is_supported_housing?
       reset_address_fields!
-    elsif form.start_year_2026_or_later? && location_changed?
+    elsif form.start_year_2026_or_later?
+      if location_changed?
         reset_address_fields!
         self.la = nil
       end
 
+      self.is_la_inferred = la.present? if is_supported_housing? && location && self[:la].blank?
+    end
+
     if scheme_has_confidential_information?
       reset_address_fields!
       self.uprn_selection = nil

app/models/form/lettings/pages/property_local_authority.rb

@@ -5,6 +5,7 @@ class Form::Lettings::Pages::PropertyLocalAuthority < ::Form::Page
     @depends_on = [
       { "is_la_inferred" => false, "is_general_needs?" => true, "form.start_year_2025_or_later?" => false, "address_search_given?" => true },
       { "is_la_inferred" => false, "is_general_needs?" => true, "form.start_year_2025_or_later?" => true },
+      { "is_la_inferred" => false, "is_supported_housing?" => true, "form.start_year_2026_or_later?" => true },
     ]
   end
 

app/models/lettings_log.rb

@@ -31,7 +31,7 @@ class LettingsLog < Log
   before_validation :process_postcode_changes!, if: :postcode_full_changed?
   before_validation :process_previous_postcode_changes!, if: :ppostcode_full_changed?
   before_validation :reset_invalidated_dependent_fields!
-  before_validation :reset_location_fields!, unless: :postcode_known?
+  before_validation :reset_location_fields!, unless: :postcode_known_or_la_derived_from_scheme_location?
   before_validation :reset_previous_location_fields!, unless: :previous_postcode_known?
   before_validation :set_derived_fields!
   before_validation :process_uprn_change!, if: :should_process_uprn_change?
@@ -375,6 +375,10 @@ class LettingsLog < Log
     postcode_known == 1
   end
 
+  def postcode_known_or_la_derived_from_scheme_location?
+    postcode_known? || (form&.start_year_2026_or_later? && is_supported_housing? && location.present?)
+  end
+
   def previous_postcode_known?
     # 0: Yes
     ppcodenk&.zero?