backend/app/controllers/material_versions_controller.rb

@@ -5,6 +5,7 @@ class MaterialVersionsController < ApplicationController
 
     page = 1 if page < 1
     limit = 1 if limit < 1
+    limit = 100 if limit > 100
 
     offset = (page - 1) * limit
 

backend/app/controllers/materials_controller.rb

@@ -14,6 +14,7 @@ class MaterialsController < ApplicationController
 
     page = 1 if page < 1
     limit = 1 if limit < 1
+    limit = 100 if limit > 100
 
     offset = (page - 1) * limit
 

backend/app/controllers/nico_tags_controller.rb

@@ -15,6 +15,7 @@ class NicoTagsController < ApplicationController
 
     page = 1 if page < 1
     limit = 1 if limit < 1
+    limit = 100 if limit > 100
 
     post_tag_max_sql =
         PostExternalTag

backend/app/controllers/post_versions_controller.rb

@@ -11,6 +11,7 @@ class PostVersionsController < ApplicationController
 
     page = 1 if page < 1
     limit = 1 if limit < 1
+    limit = 100 if limit > 100
 
     offset = (page - 1) * limit
 

backend/app/controllers/posts_controller.rb

@@ -34,6 +34,7 @@ class PostsController < ApplicationController
 
     page = 1 if page < 1
     limit = 1 if limit < 1
+    limit = 100 if limit > 100
 
     offset = (page - 1) * limit
 

backend/app/controllers/tag_versions_controller.rb

@@ -7,6 +7,7 @@ class TagVersionsController < ApplicationController
 
     page = 1 if page < 1
     limit = 1 if limit < 1
+    limit = 100 if limit > 100
 
     offset = (page - 1) * limit
 

backend/app/controllers/tags_controller.rb

@@ -33,6 +33,7 @@ class TagsController < ApplicationController
 
     page = 1 if page < 1
     limit = 1 if limit < 1
+    limit = 100 if limit > 100
 
     offset = (page - 1) * limit
 

backend/app/controllers/theatre_comments_controller.rb

@@ -2,6 +2,7 @@ class TheatreCommentsController < ApplicationController
   def index
     limit = params[:limit].to_i
     limit = 20 if limit <= 0
+    limit = 100 if limit > 100
 
     no_gt = params[:no_gt].to_i
     no_gt = 0 if no_gt < 0
@@ -9,6 +10,7 @@ class TheatreCommentsController < ApplicationController
     comments = TheatreComment
                .where(theatre_id: params[:theatre_id])
                .where('no > ?', no_gt)
+               .includes(:user)
                .order(no: :desc)
                .limit(limit)
 

backend/app/controllers/theatre_programmes_controller.rb

@@ -2,6 +2,7 @@ class TheatreProgrammesController < ApplicationController
   def index
     limit = params[:limit].to_i
     limit = 100 if limit <= 0
+    limit = 100 if limit > 100
 
     position_gt = params[:position_gt].to_i
     position_gt = 0 if position_gt < 0
@@ -10,7 +11,7 @@ class TheatreProgrammesController < ApplicationController
                  .where(theatre_id: params[:theatre_id])
                  .where('position > ?', position_gt)
                  .includes(:post)
-                 .order(position: :desc).limit(100)
+                 .order(position: :desc)
                  .limit(limit)
 
     render json: programmes.map { |programme|

backend/app/controllers/theatre_skip_events_controller.rb

@@ -2,6 +2,7 @@ class TheatreSkipEventsController < ApplicationController
   def index
     limit = params[:limit].to_i
     limit = 50 if limit <= 0
+    limit = 100 if limit > 100
 
     events =
         TheatreSkipEvent

backend/spec/requests/list_limits_spec.rb

@@ -0,0 +1,174 @@
+require 'rails_helper'
+
+RSpec.describe 'List API limits', type: :request do
+  shared_examples 'a capped list' do |default_count, minimum_count, paginated|
+    def response_rows
+      body = json
+      body.is_a?(Array) ? body : body.fetch(collection_key)
+    end
+
+    it 'caps oversized limits at 100 and preserves the 100 boundary' do
+      get path, params: { locale: 'ja', limit: 100 }
+      expect(response).to have_http_status(:ok)
+      expect(response_rows.size).to eq(100)
+      boundary_rows = response_rows
+
+      [101, 10_000].each do |limit|
+        get path, params: { locale: 'ja', limit: }
+        expect(response).to have_http_status(:ok)
+        expect(response_rows).to eq(boundary_rows)
+      end
+    end
+
+    it 'preserves the default, nonpositive and small positive limits' do
+      get path, params: { locale: 'ja' }
+      expect(response).to have_http_status(:ok)
+      expect(response_rows.size).to eq(default_count)
+
+      [0, -1].each do |limit|
+        get path, params: { locale: 'ja', limit: }
+        expect(response).to have_http_status(:ok)
+        expect(response_rows.size).to eq(minimum_count)
+      end
+
+      get path, params: { locale: 'ja', limit: 2 }
+      expect(response).to have_http_status(:ok)
+      expect(response_rows.size).to eq(2)
+    end
+
+    if paginated
+      it 'uses the capped limit for page offsets and preserves total count' do
+        get path, params: { locale: 'ja', limit: 100 }
+        first_page = response_rows
+        expect(response).to have_http_status(:ok)
+        expect(json.fetch('count')).to eq(101)
+
+        get path, params: { locale: 'ja', limit: 100, page: 2 }
+        expect(response).to have_http_status(:ok)
+        expect(response_rows.size).to eq(1)
+        second_page = response_rows
+        expect(first_page & second_page).to be_empty
+
+        get path, params: { locale: 'ja', limit: 101, page: 2 }
+        expect(response).to have_http_status(:ok)
+        expect(response_rows).to eq(second_page)
+        expect(json.fetch('count')).to eq(101)
+      end
+    end
+  end
+
+  context 'posts' do
+    let(:path) { '/posts' }
+    let(:collection_key) { 'posts' }
+    before { create_list(:post, 101) }
+
+    include_examples 'a capped list', 20, 1, true
+  end
+
+  context 'tags' do
+    let(:path) { '/tags' }
+    let(:collection_key) { 'tags' }
+    before { create_list(:tag, 101) }
+
+    include_examples 'a capped list', 20, 1, true
+  end
+
+  context 'nico tags' do
+    let(:path) { '/tags/nico' }
+    let(:collection_key) { 'tags' }
+    before { create_list(:external_tag, 101) }
+
+    include_examples 'a capped list', 20, 1, true
+  end
+
+  context 'materials' do
+    let(:path) { '/materials' }
+    let(:collection_key) { 'materials' }
+    before do
+      101.times { |index| Material.create!(url: "https://example.com/material-#{ index }") }
+    end
+
+    include_examples 'a capped list', 20, 1, true
+  end
+
+  context 'post versions' do
+    let(:path) { '/posts/versions' }
+    let(:collection_key) { 'versions' }
+    let(:post) { create(:post) }
+    before do
+      101.times do |index|
+        PostVersion.create!(post:, version_no: index + 1, event_type: 'update',
+                            url: post.url, tags: '', tags_json: [], parent_post_ids: '')
+      end
+    end
+
+    include_examples 'a capped list', 20, 1, true
+  end
+
+  context 'tag versions' do
+    let(:path) { '/tags/versions' }
+    let(:collection_key) { 'versions' }
+    let(:tag) { create(:tag) }
+    before do
+      101.times do |index|
+        TagVersion.create!(tag:, version_no: index + 1, event_type: 'update',
+                           name: 'limit tag', category: 'general', aliases: '',
+                           parent_tag_ids: '', names: {
+                               ja: { name: 'limit tag', script_code: 'Jpan',
+                                     auto_generated: false, aliases: [] } })
+      end
+    end
+
+    include_examples 'a capped list', 20, 1, true
+  end
+
+  context 'material versions' do
+    let(:path) { '/materials/versions' }
+    let(:collection_key) { 'versions' }
+    let(:material) { Material.create!(url: 'https://example.com/material') }
+    before do
+      101.times do |index|
+        MaterialVersion.create!(material:, version_no: index + 1,
+                                event_type: 'update', url: material.url)
+      end
+    end
+
+    include_examples 'a capped list', 20, 1, true
+  end
+
+  context 'theatre lists' do
+    let(:theatre) { create(:theatre) }
+    let(:post) { create(:post) }
+
+    context 'comments' do
+      let(:path) { "/theatres/#{ theatre.id }/comments" }
+      before { create_list(:theatre_comment, 101, theatre:, user: theatre.created_by_user) }
+
+      include_examples 'a capped list', 20, 20, false
+    end
+
+    context 'programmes' do
+      let(:path) { "/theatres/#{ theatre.id }/programmes" }
+      before do
+        101.times do |index|
+          TheatreProgramme.create!(theatre:, post:, position: index + 1)
+        end
+      end
+
+      include_examples 'a capped list', 100, 100, false
+    end
+
+    context 'skip events' do
+      let(:path) { "/theatres/#{ theatre.id }/skip_events" }
+      before do
+        101.times do |index|
+          TheatreSkipEvent.create!(theatre:, post:,
+                                   skipped_by_user: theatre.created_by_user,
+                                   created_at: Time.utc(2026, 1, 1) + index.seconds)
+        end
+      end
+
+      include_examples 'a capped list', 50, 50, false
+    end
+  end
+end