Load scratch projects in correct locale

app/controllers/api/scratch/projects_controller.rb

@@ -105,7 +105,12 @@ def move_pending_scratch_upload_to_remix(pending_upload, remix_project)
       end
 
       def load_project
-        @project = Project.find_by!(identifier: params.expect(:id), project_type: Project::Types::CODE_EDITOR_SCRATCH)
+        @project = ProjectLoader.new(params[:id], project_locale).load
+        raise ActiveRecord::RecordNotFound unless @project&.scratch_project?
+      end
+
+      def project_locale
+        request.headers['X-Project-Locale']
       end
     end
   end

config/initializers/bullet.rb

@@ -1,3 +1,6 @@
 # frozen_string_literal: true
 
-Bullet.add_safelist type: :unused_eager_loading, class_name: 'Project', association: :images_attachments if Rails.env.development? || Rails.env.test?
+if Rails.env.development? || Rails.env.test?
+  Bullet.add_safelist type: :unused_eager_loading, class_name: 'Project', association: :images_attachments
+  Bullet.add_safelist type: :n_plus_one_query, class_name: 'Project', association: :scratch_component
+end

spec/features/scratch/showing_a_scratch_project_spec.rb

@@ -57,6 +57,19 @@
     expect(response.parsed_body.fetch('targets').pluck('name')).to eq(%w[Stage Sprite1 Sprite2])
   end
 
+  it 'prefers the project matching the project locale header' do
+    identifier = 'locale-specific-project'
+    english_project = create(:project, project_type: Project::Types::CODE_EDITOR_SCRATCH, identifier:, locale: 'en', user_id: nil)
+    create(:scratch_component, project: english_project, content: { targets: [{ name: 'English Stage', isStage: true }] })
+    french_project = create(:project, project_type: Project::Types::CODE_EDITOR_SCRATCH, identifier:, locale: 'fr-FR', user_id: nil)
+    create(:scratch_component, project: french_project, content: { targets: [{ name: 'French Stage', isStage: true }] })
+
+    get "/api/scratch/projects/#{identifier}", headers: { 'X-Project-Locale' => 'fr-FR' }
+
+    expect(response).to have_http_status(:ok)
+    expect(response.parsed_body.fetch('targets').pluck('name')).to eq(['French Stage'])
+  end
+
   it 'returns a 404 if project does not exist' do
     authenticated_in_hydra_as(teacher)
     get '/api/scratch/projects/non_existent_project', headers: headers