AI: address review on PR #461

backend/app/services/post_tag_search.rb

@@ -3,8 +3,8 @@ class PostTagSearch
   def self.literals(locale, raw)
     tokens = raw.split.reject { _1.downcase == 'type:or' }
     names = tokens.map { _1.sub(/\Anot:/i, '') }
-    registered = TagName.where(language_code: locale.language_code, name: names)
-        .pluck(:name, :tag_id).to_h
+    registered = matching_names(TagName.where(language_code: locale.language_code),
+        names, 'tag_names.name', :tag_id).to_h
     primary = TagName.where(language_code: locale.language_code,
         tag_id: registered.values, primary_flg: true).pluck(:tag_id, :name).to_h
     tokens.zip(names).map do |token, name|
@@ -19,12 +19,25 @@ class PostTagSearch
 
   def self.references_for(locale, literals)
     names = literals.map { _1[:name] }.uniq
-    internal = TagName.where(language_code: locale.language_code, name: names)
-        .pluck(:name, :tag_id).group_by(&:first)
-    external = names.empty? ? {} : ExternalTag.where(
-        "CONCAT(platform, ':', name) IN (?)", names)
-        .pluck(Arel.sql("CONCAT(platform, ':', name)"), :id).group_by(&:first)
+    internal = matching_names(TagName.where(language_code: locale.language_code),
+        names, 'tag_names.name', :tag_id).group_by(&:first)
+    external = matching_names(ExternalTag.all, names,
+        "CONCAT(external_tags.platform, ':', external_tags.name)", :id).group_by(&:first)
     names.to_h { |name| [name, [internal.fetch(name, []).map(&:last).uniq,
                               external.fetch(name, []).map(&:last).uniq]] }
   end
+
+  def self.matching_names(scope, names, expression, identifier)
+    return [] if names.empty?
+
+    queries = names.uniq.map do |name|
+      scope.klass.sanitize_sql_array(['SELECT ? AS name', name])
+    end
+    # Return the input spelling so Ruby does not recheck database equivalence.
+    scope.joins(<<~SQL).pluck(Arel.sql('search_names.name'), identifier)
+      INNER JOIN (#{ queries.join(' UNION ALL ') }) AS search_names
+        ON #{ expression } = search_names.name COLLATE utf8mb4_0900_ai_ci
+    SQL
+  end
+  private_class_method :matching_names
 end

backend/db/migrate/20261115000000_add_post_count_index_to_tags.rb

@@ -1,5 +0,0 @@
-class AddPostCountIndexToTags < ActiveRecord::Migration[8.0]
-  def change
-    add_index :tags, :post_count
-  end
-end

backend/db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2026_11_15_000000) do
+ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
   create_table "active_storage_attachments", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -630,7 +630,6 @@ ActiveRecord::Schema[8.0].define(version: 2026_11_15_000000) do
     t.integer "post_count", default: 0, null: false
     t.integer "version_no", null: false
     t.index ["deprecated_at"], name: "index_tags_on_deprecated_at"
-    t.index ["post_count"], name: "index_tags_on_post_count"
     t.check_constraint "(`deprecated_at` is null) or (`category` <> _utf8mb4'nico')", name: "chk_tags_deprecated_at_not_nico"
     t.check_constraint "`version_no` > 0", name: "chk_tags_version_no_positive"
   end

backend/spec/models/tag_spec.rb

@@ -2,19 +2,6 @@ require 'rails_helper'
 
 RSpec.describe Tag, type: :model do
   include WikiRecords
-
-  describe 'post_count index' do
-    it 'has a non-unique index on post_count alone' do
-      indexes = described_class.connection.indexes(described_class.table_name)
-
-      expect(indexes).to include(
-          have_attributes(
-              name: 'index_tags_on_post_count',
-              columns: ['post_count'],
-              unique: false))
-    end
-  end
-
   describe '#has_description?' do
     let(:tag) { create(:tag) }
 

backend/spec/requests/posts_spec.rb

@@ -206,6 +206,25 @@ RSpec.describe 'Posts API', type: :request do
     end
 
     context 'when q is provided' do
+      ['SPEC_TAG', 'SpEc_TaG', 'spec_tág', 'MANKO', 'MaNkO', 'mánko'].each do |name|
+        it "matches #{ name } using database collation" do
+          get '/posts', params: { locale: 'ja', tags: name }
+
+          expect(response).to have_http_status(:ok)
+          expect(json.fetch('count')).to eq(2)
+          expect(json.fetch('posts').map { _1.fetch('id') })
+              .to contain_exactly(post_record.id, hit_post.id)
+        end
+
+        it "excludes #{ name } using database collation" do
+          get '/posts', params: { locale: 'ja', tags: "not:#{ name }" }
+
+          expect(response).to have_http_status(:ok)
+          expect(json.fetch('count')).to eq(1)
+          expect(json.fetch('posts').map { _1.fetch('id') }).to eq([miss_post.id])
+        end
+      end
+
       it 'filters posts by q (hit case)' do
         get '/posts', params: { tags: 'spec_tag' }
 
@@ -266,6 +285,26 @@ RSpec.describe 'Posts API', type: :request do
         PostExternalTag.create!(post: miss_post, external_tag:)
       end
 
+      ['NICO:SEARCH_EXTERNAL', 'NiCo:SeArCh_ExTeRnAl', 'nico:séarch_external'].each do |name|
+        it "matches #{ name } using database collation" do
+          get '/posts', params: { locale: 'ja', tags: name }
+
+          expect(response).to have_http_status(:ok)
+          expect(json.fetch('count')).to eq(2)
+          expect(json.fetch('posts').map { _1.fetch('id') })
+              .to contain_exactly(miss_post.id, both_post.id)
+        end
+
+        it "excludes #{ name } using database collation" do
+          get '/posts', params: { locale: 'ja', tags: "not:#{ name }" }
+
+          expect(response).to have_http_status(:ok)
+          expect(json.fetch('count')).to eq(2)
+          expect(json.fetch('posts').map { _1.fetch('id') })
+              .to contain_exactly(post_record.id, hit_post.id)
+        end
+      end
+
       it 'keeps internal name searches independent of colliding external ids' do
         get '/posts', params: { tags: primary_tag_name_for(tag, 'ja').name }
 

frontend/src/components/layout/SidebarComponent.test.tsx

@@ -70,16 +70,6 @@ describe ('SidebarComponent', () => {
     vi.spyOn (HTMLElement.prototype, 'hasPointerCapture').mockReturnValue (true)
   })
 
-  it ('limits sidebar scrolling to desktop to avoid clipping mobile suggestions', () => {
-    renderSidebar ()
-
-    // jsdom has no layout; guard the responsive classes responsible for clipping.
-    const sidebar = screen.getByText ('Sidebar body')
-
-    expect (sidebar).not.toHaveClass ('overflow-y-auto')
-    expect (sidebar).toHaveClass ('md:overflow-y-auto')
-  })
-
   it ('uses maxWidth without applying the container main-width reserve twice', async () => {
     localStorage.setItem ('sidebar:test-sidebar:left:width', '700')
     const onWidthChange = vi.fn ()

frontend/src/components/layout/SidebarComponent.tsx

@@ -339,7 +339,7 @@ const SidebarComponent: FC<Props> = ({
 	  </style>
 	</Helmet>
 
-	<div className="h-full md:overflow-y-auto p-4 sidebar">
+	<div className="h-full overflow-y-auto p-4 sidebar">
 	  {children}
 	</div>
 

frontend/src/pages/tags/TagDetailPage.test.tsx

@@ -35,10 +35,6 @@ const renderPage = () =>
 describe ('TagDetailPage', () => {
   beforeEach (() => {
     vi.clearAllMocks ()
-    tagsApi.fetchTag.mockReset ()
-    api.apiPut.mockReset ()
-    api.isApiError.mockReset ()
-    toastApi.toast.mockReset ()
     api.isApiError.mockReturnValue (false)
   })
 
@@ -55,11 +51,8 @@ describe ('TagDetailPage', () => {
   })
 
   it ('submits edited tag fields', async () => {
-    const updatedTag = buildTag ({ id: 7, name: 'new', aliases: ['alias'] })
-    tagsApi.fetchTag
-	.mockResolvedValue (updatedTag)
-	.mockResolvedValueOnce (buildTag ({ id: 7, name: 'old' }))
-    api.apiPut.mockResolvedValueOnce (updatedTag)
+    tagsApi.fetchTag.mockResolvedValueOnce (buildTag ({ id: 7, name: 'old' }))
+    api.apiPut.mockResolvedValueOnce (buildTag ({ id: 7, name: 'new', aliases: ['alias'] }))
 
     renderPage ()