add collection counts endpoint

app/controllers/api/v1/collection_controller.rb

@@ -0,0 +1,34 @@
+module Api
+  module V1
+    class CollectionController < ApiController
+      before_action :set_target_user
+      before_action :check_collection_access
+
+      # GET /api/v1/users/:user_id/collection/counts
+      # Returns total counts for all collection entity types
+      def counts
+        render json: {
+          characters: @target_user.collection_characters.count,
+          weapons: @target_user.collection_weapons.count,
+          summons: @target_user.collection_summons.count,
+          artifacts: @target_user.collection_artifacts.count
+        }
+      end
+
+      private
+
+      def set_target_user
+        @target_user = User.find(params[:user_id])
+      rescue ActiveRecord::RecordNotFound
+        render json: { error: "User not found" }, status: :not_found
+      end
+
+      def check_collection_access
+        return if @target_user.nil?
+        unless @target_user.collection_viewable_by?(current_user)
+          render json: { error: "You do not have permission to view this collection" }, status: :forbidden
+        end
+      end
+    end
+  end
+end

config/routes.rb

@@ -250,6 +250,7 @@ Rails.application.routes.draw do
     # Reading collections - works for any user with privacy check
     scope 'users/:user_id' do
       namespace :collection do
+        get :counts, controller: '/api/v1/collection'
         resources :characters, only: [:index, :show], controller: '/api/v1/collection_characters'
         resources :weapons, only: [:index, :show], controller: '/api/v1/collection_weapons'
         resources :summons, only: [:index, :show], controller: '/api/v1/collection_summons'