Add new endpoints to PartiesController

* `preview` shows the preview and queues it up for generation if it doesn't exist yet
* `regenerate_preview` allows the party owner to force regeneration of previews

app/controllers/api/v1/parties_controller.rb

@@ -116,6 +116,30 @@ module Api
         render_party_json(@parties, count, total_pages)
       end
 
+      def preview
+        party = Party.find_by!(shortcode: params[:id])
+
+        preview_service = PreviewService::Coordinator.new(party)
+        redirect_to preview_service.preview_url
+      end
+
+      def regenerate_preview
+        party = Party.find_by!(shortcode: params[:id])
+
+        # Ensure only party owner can force regeneration
+        unless current_user && party.user_id == current_user.id
+          return render_unauthorized_response
+        end
+
+        preview_service = PreviewService::Coordinator.new(party)
+        if preview_service.force_regenerate
+          render json: { status: 'Preview regeneration started' }
+        else
+          render json: { error: 'Preview regeneration failed' },
+                 status: :unprocessable_entity
+        end
+      end
+
       private
 
       def authorize

config/routes.rb

@@ -24,6 +24,8 @@ Rails.application.routes.draw do
 
       get 'parties/favorites', to: 'parties#favorites'
       get 'parties/:id', to: 'parties#show'
+      get 'parties/:id/preview', to: 'parties#preview'
+      post 'parties/:id/regenerate_preview', to: 'parties#regenerate_preview'
       post 'parties/:id/remix', to: 'parties#remix'
 
       put 'parties/:id/jobs', to: 'jobs#update_job'
@@ -72,4 +74,20 @@ Rails.application.routes.draw do
       delete 'favorites', to: 'favorites#destroy'
     end
   end
+
+  if Rails.env.development?
+    get '/party-previews/*filename', to: proc { |env|
+      filename = env['action_dispatch.request.path_parameters'][:filename]
+      path = Rails.root.join('storage', 'party-previews', filename)
+
+      if File.exist?(path)
+        [200, {
+          'Content-Type' => 'image/png',
+          'Cache-Control' => 'no-cache' # Prevent caching during development
+        }, [File.read(path)]]
+      else
+        [404, { 'Content-Type' => 'text/plain' }, ['Preview not found']]
+      end
+    }
+  end
 end