style(rubocop): resolve three next quick-win todo entries

.rubocop_todo.yml

@@ -155,24 +155,6 @@ Rails/HelperInstanceVariable:
   Exclude:
     - 'app/helpers/email_helper.rb'
 
-# Offense count: 2
-# Configuration parameters: IgnoreScopes.
-Rails/InverseOf:
-  Exclude:
-    - 'app/models/member.rb'
-    - 'app/models/workshop_invitation.rb'
-
-# Offense count: 2
-Rails/LexicallyScopedActionFilter:
-  Exclude:
-    - 'app/controllers/concerns/admin/sponsor_concerns.rb'
-
-# Offense count: 2
-Rails/OutputSafety:
-  Exclude:
-    - 'app/helpers/application_helper.rb'
-    - 'app/presenters/address_presenter.rb'
-
 # Offense count: 9
 # Configuration parameters: ForbiddenMethods, AllowedMethods.
 # ForbiddenMethods: decrement!, decrement_counter, increment!, increment_counter, insert, insert!, insert_all, insert_all!, toggle!, touch, touch_all, update_all, update_attribute, update_column, update_columns, update_counters, upsert, upsert_all

app/controllers/admin/workshops_controller.rb

@@ -1,9 +1,10 @@
 class Admin::WorkshopsController < Admin::ApplicationController
-  include  Admin::SponsorConcerns
-  include  Admin::WorkshopConcerns
+  include Admin::WorkshopConcerns
 
   before_action :set_workshop_by_id, only: %i[show edit destroy update]
   before_action :set_and_decorate_workshop, only: %i[attendees_checklist attendees_emails send_invites changes]
+  before_action :set_workshop, only: %i[sponsor destroy_sponsor host destroy_host]
+  before_action :set_sponsor, only: %i[sponsor host]
 
   WORKSHOP_DELETION_TIME_FRAME_SINCE_CREATION = 4.hours
 
@@ -114,6 +115,36 @@ def changes
     @student_invitations = invitations.to_students
   end
 
+  def sponsor
+    flash[:notice] = if workshop_sponsors.save
+      'Sponsor added successfully'
+    else
+      workshop_sponsors.errors.full_messages.to_s
+    end
+    redirect_back fallback_location: root_path
+  end
+
+  def destroy_sponsor
+    @sponsor = Sponsor.find(params[:sponsor_id])
+    @workshop.workshop_sponsors.find_by(sponsor: @sponsor).destroy
+    redirect_back fallback_location: root_path
+  end
+
+  def host
+    set_sponsor
+    @workshop_sponsor = WorkshopSponsor.find_or_create_by(workshop: @workshop, sponsor: @sponsor)
+    @workshop_sponsor.update(host: true)
+    flash[:notice] = 'Host set successfully'
+
+    redirect_back fallback_location: root_path
+  end
+
+  def destroy_host
+    @workshop.workshop_sponsors.find_by(host: true).update(host: false)
+
+    redirect_back fallback_location: root_path
+  end
+
   private
 
   def workshop_params
@@ -202,4 +233,12 @@ def update_workshop_details
     assign_organisers(organiser_ids)
     assign_host(host_id)
   end
+
+  def set_sponsor
+    @sponsor = Sponsor.find(params[:workshop][:sponsor_ids])
+  end
+
+  def workshop_sponsor(host = false)
+    @workshop_sponsor ||= WorkshopSponsor.new(workshop: @workshop, sponsor: @sponsor, host: host)
+  end
 end

app/helpers/application_helper.rb

@@ -20,7 +20,10 @@ def retrieve_title
   end
 
   def dot_markdown(text)
+    # Commonmarker sanitises raw HTML; `.html_safe` prevents Rails double-escaping the result
+    # rubocop:disable Rails/OutputSafety
     Commonmarker.to_html(text).html_safe
+    # rubocop:enable Rails/OutputSafety
   end
 
   def belongs_to_group?(group)

app/models/member.rb

@@ -17,7 +17,7 @@ class Member < ApplicationRecord
   has_many :workshop_invitations
   has_many :invitations
   has_many :auth_services
-  has_many :feedbacks, foreign_key: :coach_id
+  has_many :feedbacks, foreign_key: :coach_id, inverse_of: :coach
   has_many :subscriptions
   has_many :groups, through: :subscriptions
   has_many :member_notes

app/models/workshop_invitation.rb

@@ -4,7 +4,7 @@ class WorkshopInvitation < ApplicationRecord
   belongs_to :workshop
   belongs_to :member
   belongs_to :overrider, foreign_key: :last_overridden_by_id, class_name: 'Member', inverse_of: false, optional: true
-  has_one :waiting_list, foreign_key: :invitation_id
+  has_one :waiting_list, foreign_key: :invitation_id, inverse_of: :invitation
 
   validates :workshop, :member, presence: true
   validates :member_id, uniqueness: { scope: %i[workshop_id role] }

app/presenters/address_presenter.rb

@@ -5,10 +5,13 @@ def to_html
     city_and_postal_code = [model.city, model.postal_code].delete_if(&:empty?)
                                                           .join(', ')
 
+    # Every element is html_escape'd; `.html_safe` prevents Rails double-escaping the joined string
+    # rubocop:disable Rails/OutputSafety
     [model.flat, model.street, city_and_postal_code, lat, lng]
       .delete_if(&:empty?)
       .map { |line| ERB::Util.html_escape(line) }
       .join('<br/>').html_safe
+    # rubocop:enable Rails/OutputSafety
   end
 
   def for_map