diff --git a/backend/spec/requests/list_limits_spec.rb b/backend/spec/requests/list_limits_spec.rb
new file mode 100644
index 0000000..ec0a0ef
--- /dev/null
+++ b/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