AI: address review on PR #477

.gitea/ISSUE_TEMPLATE.md

@@ -0,0 +1,35 @@
+## 背景
+
+なぜ必要か。
+
+## 対象範囲
+
+- backend:
+- frontend:
+- docs:
+- migration:
+
+## やること
+
+- [ ] 
+
+## 受け入れ条件
+
+- [ ] 
+
+## 実行すべき確認
+
+- [ ] `cd backend && bundle exec rspec`
+- [ ] `cd frontend && npm run build`
+- [ ] `cd frontend && npm run lint`
+
+## 禁止事項
+
+- unrelated refactor はしない
+- 既存 API response shape を壊さない
+- 認証・認可・BAN を弱めない
+
+## Codex への指示
+
+この issue を読んで実装してください。
+不明点があれば、実装前に調査結果と選択肢を提示してください。

backend/app/controllers/post_versions_controller.rb

@@ -100,9 +100,18 @@ class PostVersionsController < ApplicationController
 
   def external_tag_names_for snapshots
     ids = snapshots.flatten.filter_map { _1['external_tag_id'] }.uniq
-    ExternalTag.where(id: ids).pluck(:id, :platform, :name).to_h { |id, platform, name|
+    names = ExternalTag.where(id: ids).pluck(:id, :platform, :name).to_h { |id, platform, name|
       [id, "#{ platform }:#{ name }"]
     }
+    missing_ids = ids - names.keys
+
+    HistoryAccess.visible(NicoTagVersion.all)
+        .where(tag_id: missing_ids)
+        .order(:tag_id, version_no: :desc)
+        .pluck(:tag_id, :name)
+        .each { |id, name| names[id] ||= name }
+
+    names
   end
 
   def snapshot_tag_literals snapshots, tag_names, external_tag_names

backend/app/controllers/tag_descriptions_controller.rb

@@ -1,4 +1,34 @@
 class TagDescriptionsController < ApplicationController
+  rescue_from TagDescriptionOperation::Conflict, with: :render_conflict
+
+  def index
+    locale = resolve_locale!
+    descriptions = HistoryAccess.current(TagDescription.all, TagDescriptionVersion)
+        .where(language_code: locale.language_code).includes(tag: :tag_names)
+        .order(updated_at: :desc, id: :asc)
+    title = params[:title].to_s.strip
+    if title.present?
+      pattern = "%#{ ApplicationRecord.sanitize_sql_like(title) }%"
+      descriptions = descriptions.joins(tag: :tag_names)
+          .where(tag_names: { language_code: locale.language_code, primary_flg: true })
+          .where('tag_names.name LIKE ?', pattern).limit(20)
+    end
+    render json: descriptions.map { WikiPageRepr.tag_description(locale, _1) }
+  end
+
+  def show_by_id
+    locale = resolve_locale!
+    reference = TagDescription.find_by(id: params[:description_id])
+    return head :not_found unless reference
+
+    HistoryAccess.require_current!(reference, TagDescriptionVersion)
+    description = TagDescription.find_by(tag_id: reference.tag_id,
+                                         language_code: locale.language_code)
+    return head :not_found unless description
+
+    render json: representation(description)
+  end
+
   def show
     locale = resolve_locale!
     description = TagDescription.find_by(tag_id: params[:id], language_code: locale.language_code)
@@ -18,6 +48,25 @@ class TagDescriptionsController < ApplicationController
     render json: representation(description)
   end
 
+  def create
+    return head :unauthorized unless current_user
+    return head :forbidden unless current_user.gte_member?
+
+    locale = resolve_locale!
+    title = params[:title].to_s.strip
+    body = params[:body].to_s
+    return render_unprocessable_entity('タイトルは必須です．', field: :title) if title.blank?
+    return render_unprocessable_entity('本文は必須です．', field: :body) if body.blank?
+    return render_unprocessable_entity field: :title if title.include?(':')
+
+    tag_name = TagName.find_by(language_code: locale.language_code, name: title)
+    return render_unprocessable_entity field: :title unless tag_name&.tag
+
+    description = TagDescriptionOperation.create!(
+        locale, tag: tag_name.tag, body:, created_by_user: current_user)
+    render json: representation(description), status: :created
+  end
+
   def update
     return head :unauthorized unless current_user
     return head :forbidden unless current_user.gte_member?
@@ -32,7 +81,9 @@ class TagDescriptionsController < ApplicationController
     description = TagDescription.find_by(tag:, language_code: locale.language_code)
 
     if description
-      TagDescriptionOperation.update!(locale, tag:, body:, updated_by_user: current_user)
+      TagDescriptionOperation.update_with_title!(
+          locale, tag:, body:, title: params[:title], actor: current_user,
+          base_revision_id: params[:base_revision_id].presence)
       description.reload
       render json: representation(description)
     else
@@ -48,8 +99,20 @@ class TagDescriptionsController < ApplicationController
 
   private
 
+  def render_conflict error
+    render json: { error: 'conflict', message: error.message }, status: :conflict
+  end
+
   def representation description
     HistoryAccess.require_current!(description, TagDescriptionVersion)
+    if params[:document] == '1'
+      locale = resolve_locale!
+      version = HistoryAccess.visible(TagDescriptionVersion.all).find_by!(
+          tag_id: description.tag_id, language_code: description.language_code,
+          version_no: description.version_no)
+      return WikiPageRepr.tag_description(locale, description).merge(revision_id: version.id)
+    end
+
     description.as_json(only: [
         :tag_id,
         :language_code,

backend/app/controllers/tag_groups_controller.rb

@@ -1,7 +1,22 @@
 class TagGroupsController < ApplicationController
+  rescue_from TagGroupMarkdownParser::InvalidDocument,
+              TagGroupMarkdownRenderer::UnsupportedStructure, with: :render_document_error
+
   def index
     locale = resolve_locale!
-    groups = HistoryAccess.current(TagGroup.all, TagGroupVersion).includes(:created_by_user, :updated_by_user).order(:id)
+    groups = HistoryAccess.current(TagGroup.all, TagGroupVersion)
+        .includes(:created_by_user, :updated_by_user)
+    if params[:document] == '1'
+      groups = groups.order(updated_at: :desc, id: :asc)
+      title = params[:title].to_s.strip
+      if title.present?
+        pattern = "%#{ ApplicationRecord.sanitize_sql_like(title) }%"
+        groups = groups.where('CONCAT(?, name) LIKE ? OR CONCAT(?, name) LIKE ?',
+                              TagGroupRepr::PREFIX, pattern, 'tag_group:', pattern).limit(20)
+      end
+      return render json: groups.map { WikiPageRepr.tag_group(_1) }
+    end
+    groups = groups.order(:id)
     render json: TagGroupRepr.many(locale, groups.to_a)
   end
 
@@ -10,7 +25,15 @@ class TagGroupsController < ApplicationController
     group = TagGroup.includes(:created_by_user, :updated_by_user).find_by(id: params[:id])
     return head :not_found unless group
 
-    render json: TagGroupRepr.one(locale, group)
+    render json: representation(locale, group)
+  end
+
+  def show_by_name
+    locale = resolve_locale!
+    group = TagGroup.includes(:created_by_user, :updated_by_user).find_by(name: params[:name])
+    return head :not_found unless group
+
+    render json: representation(locale, group)
   end
 
   def create
@@ -18,8 +41,8 @@ class TagGroupsController < ApplicationController
     return head :forbidden unless current_user.gte_member?
 
     locale = resolve_locale!
-    group = TagGroupOperation.create!(locale, **write_attributes, actor: current_user)
-    render json: TagGroupRepr.one(locale, group), status: :created
+    group = TagGroupOperation.create!(locale, **write_attributes(locale), actor: current_user)
+    render json: representation(locale, group), status: :created
   end
 
   def update
@@ -30,13 +53,39 @@ class TagGroupsController < ApplicationController
     group = TagGroup.find_by(id: params[:id])
     return head :not_found unless group
 
-    TagGroupOperation.update!(locale, group:, **write_attributes, actor: current_user)
-    render json: TagGroupRepr.one(locale, group.reload)
+    TagGroupOperation.update!(locale, group:, **write_attributes(locale, group:), actor: current_user)
+    render json: representation(locale, group.reload)
   end
 
   private
 
-  def write_attributes
+  def render_document_error error
+    render_unprocessable_entity(error.message)
+  end
+
+  def representation locale, group
+    representation = TagGroupRepr.one(locale, group)
+    return representation unless params[:document] == '1'
+
+    version = TagGroupRepr.current_version(group)
+    raise ActiveRecord::RecordNotFound unless version
+
+    TagGroupRepr.document(representation, version)
+  end
+
+  def write_attributes locale, group: nil
+    if params.key?(:body)
+      body = params[:body].to_s
+      if body.blank?
+        group ||= TagGroup.new
+        group.errors.add(:body, :blank)
+        raise ActiveRecord::RecordInvalid, group
+      end
+      parsed = TagGroupMarkdownParser.parse(locale, body:, group:)
+      return parsed.except(:compatibility_body).merge(
+          name: params[:name], require_compatibility: true)
+    end
+
     { name: params[:name], description: params[:description],
       members: params[:members], placements: params[:placements] }
   end

backend/app/controllers/wiki_pages_controller.rb

@@ -6,6 +6,11 @@ class WikiPagesController < ApplicationController
   def index
     locale = resolve_locale!
 
+    resource_type = params[:resource_type]
+    unless resource_type.nil? || ['tag_description', 'tag_group'].include?(resource_type)
+      return head :bad_request
+    end
+
     title = params[:title].to_s.strip
     descriptions =
         HistoryAccess.current(TagDescription.all, TagDescriptionVersion)
@@ -14,6 +19,8 @@ class WikiPagesController < ApplicationController
 
     descriptions = descriptions.order(updated_at: :desc, id: :asc)
     tag_groups = HistoryAccess.current(TagGroup.all, TagGroupVersion).order(updated_at: :desc, id: :asc)
+    descriptions = descriptions.none if resource_type == 'tag_group'
+    tag_groups = tag_groups.none if resource_type == 'tag_description'
     if title.present?
       pattern = "%#{ ApplicationRecord.sanitize_sql_like(title) }%"
       descriptions =
@@ -246,25 +253,8 @@ class WikiPagesController < ApplicationController
 
     base_revision_id = params[:base_revision_id].presence
 
-    ApplicationRecord.transaction do
-      SharedResourceIdAllocator.lock_space!(Tag, 'tags')
-      tag.lock!
-      old_title = tag_name.name
-      if title != old_title
-        TagVersioning.ensure_snapshot!(tag, created_by_user: current_user)
-      end
-
-      tag_name.update!(name: title) if title != old_title
-
-      message = params[:message].presence
-      TagDescriptionOperation.update!(locale, tag:, body:, updated_by_user: current_user,
-                                      message:, base_revision_id:)
-
-      if title != old_title
-        tag.reload
-        TagVersionRecorder.record!(tag:, event_type: :update, created_by_user: current_user)
-      end
-    end
+    TagDescriptionOperation.update_with_title!(
+        locale, tag:, body:, title:, actor: current_user, base_revision_id:)
 
     head :ok
   rescue ActiveRecord::RecordInvalid => e
@@ -326,21 +316,9 @@ class WikiPagesController < ApplicationController
   end
 
   def render_group_representation representation, version, body: nil, status: :ok
-    body ||= TagGroupMarkdownRenderer.render(representation)
-    versions = HistoryAccess.visible(TagGroupVersion.all).where(tag_group_id: version.tag_group_id)
-    pred = versions.find_by(version_no: version.version_no - 1)&.id
-    succ = versions.find_by(version_no: version.version_no + 1)&.id
-    updated_at = version.created_at
-    render json: {
-        'id' => version.tag_group_id,
-        'resource_type' => 'tag_group',
-        'title' => "#{ TagGroupRepr::PREFIX }#{ representation.fetch('name') }",
-        'deprecated_at' => nil,
-        'body' => body,
-        'revision_id' => version.id,
-        'pred' => pred,
-        'succ' => succ,
-        'updated_at' => updated_at }, status:
+    document = TagGroupRepr.document(representation, version)
+    document['body'] = body if body
+    render json: document, status:
   rescue TagGroupMarkdownRenderer::UnsupportedStructure => error
     render_unprocessable_entity(error.message)
   end

backend/app/models/external_tag.rb

@@ -1,11 +1,8 @@
 class ExternalTag < ApplicationRecord
   before_create { SharedResourceIdAllocator.assign!(self) }
-  # Must run before dependent association callbacks.
-  before_destroy :prevent_destroy
 
   enum :platform, nico: 'nico'
   validates :platform, presence: true, inclusion: { in: ExternalTag.platforms.keys }
-  validate :immutable_identity, on: :update
 
   has_many :post_external_tags, dependent: :delete_all
   has_many :posts, through: :post_external_tags
@@ -19,21 +16,11 @@ class ExternalTag < ApplicationRecord
 
   has_many :linked_tags, through: :nico_tag_relations, source: :tag
 
-  def snapshot_linked_tag_ids = linked_tags.distinct.order(:id).pluck(:id)
-
-  def delete
-    raise ActiveRecord::ReadOnlyRecord, '外部タグは削除できません．'
-  end
-
-  private
-
-  def immutable_identity
-    errors.add(:platform, 'は変更できません．') if will_save_change_to_platform?
-    errors.add(:name, 'は変更できません．') if will_save_change_to_name?
-  end
-
-  def prevent_destroy
-    errors.add(:base, '外部タグは削除できません．')
-    throw(:abort)
+  def snapshot_linked_tag_names language_code = 'ja'
+    linked_tags
+        .joins(:tag_names)
+        .where(tag_names: { language_code:, primary_flg: true })
+        .order('tag_names.name')
+        .pluck('tag_names.name')
   end
 end

backend/app/models/history_access.rb

@@ -106,7 +106,21 @@ class HistoryAccess < ActiveSupport::CurrentAttributes
              snapshot_reference(TagVersion, row),
              snapshot_reference(NicoTagVersion, row, external: true)]
     when 'nico_tag_versions'
-      [list_reference('tag_versions', 'tag_id', "#{ row }.linked_tag_ids")]
+      # Legacy linked_tags snapshots contain names, not IDs. Match recorded names
+      # conservatively; never expose a private linked name through an external tag.
+      names = "JSON_MERGE_PRESERVE(JSON_ARRAY(private_tag.name), " +
+          "COALESCE(JSON_EXTRACT(private_tag.names, '$**.name'), JSON_ARRAY()))"
+      # DISTINCT prevents merging this independent name set into the correlated scan.
+      # Keep byte-distinct names even when the column collation considers them equal.
+      private_names = 'SELECT DISTINCT private_name.name, ' +
+          'CAST(private_name.name AS BINARY) AS name_bytes FROM tag_versions private_tag ' +
+          "JOIN (#{ discarded_keys('tag_versions', 'tag_id') }) blocked " +
+          'ON blocked.tag_id = private_tag.tag_id ' +
+          "JOIN JSON_TABLE(#{ names }, '$[*]' COLUMNS (name TEXT PATH '$')) private_name " +
+          "WHERE private_name.name <> ''"
+      ["NOT EXISTS (SELECT 1 FROM (#{ private_names }) private_name WHERE " +
+          "LOCATE(CONCAT(' ', private_name.name, ' '), " +
+          "CONCAT(' ', COALESCE(#{ row }.linked_tags, ''), ' ')) > 0)"]
     when 'tag_versions'
       [list_reference('tag_versions', 'tag_id', "#{ row }.parent_tag_ids")]
     when 'tag_description_versions'

backend/app/models/nico_tag_version.rb

@@ -3,10 +3,5 @@ class NicoTagVersion < ApplicationRecord
 
   belongs_to :external_tag, foreign_key: :tag_id, inverse_of: :nico_tag_versions
 
-  validates :event_type, inclusion: { in: ['create', 'update'] }
-
-  def name
-    tag = external_tag
-    "#{ tag.platform }:#{ tag.name }" if tag
-  end
+  validates :name, presence: true
 end

backend/app/representations/counts_version_repr.rb

@@ -139,8 +139,6 @@ class CountsVersionRepr
     result = {}
     table = model.table_name
     comparison = @inclusive ? '<=' : '<'
-    name = model == NicoTagVersion ?
-        CountsResourceDefinition.new('nico_tags').expression('name', table) : 'name'
     requests.each_slice(100) do |batch|
       queries = batch.map do |id, point|
         scope = HistoryAccess.visible(model.where(tag_id: id))
@@ -150,8 +148,7 @@ class CountsVersionRepr
                 "AND newer.version_no > #{ table }.version_no)", point)
         quoted = model.connection.quote(point.iso8601(6))
         names = model == TagVersion ? 'names' : 'JSON_OBJECT() AS names'
-        scope.select("tag_id, #{ name } AS name, #{ names }, " +
-            "#{ quoted } AS reference_point").to_sql
+        scope.select("tag_id, name, #{ names }, #{ quoted } AS reference_point").to_sql
       end
       next if queries.empty?
 

backend/app/representations/tag_group_repr.rb

@@ -56,6 +56,21 @@ module TagGroupRepr
       'updated_at' => wiki_page.updated_at }
   end
 
+  def document representation, version
+    HistoryAccess.require!(version)
+    versions = HistoryAccess.visible(TagGroupVersion.all)
+        .where(tag_group_id: version.tag_group_id)
+    { 'id' => version.tag_group_id,
+      'resource_type' => 'tag_group',
+      'title' => "#{ PREFIX }#{ representation.fetch('name') }",
+      'deprecated_at' => nil,
+      'body' => TagGroupMarkdownRenderer.render(representation),
+      'revision_id' => version.id,
+      'pred' => versions.find_by(version_no: version.version_no - 1)&.id,
+      'succ' => versions.find_by(version_no: version.version_no + 1)&.id,
+      'updated_at' => version.created_at }
+  end
+
   def current_version group
     HistoryAccess.visible(TagGroupVersion.all).find_by(tag_group_id: group.id, version_no: group.version_no)
   end

backend/app/services/counts_candidates.rb

@@ -28,18 +28,16 @@ class CountsCandidates
                [external, 'external', 'NULL', 'JSON_OBJECT()']]
     sources = sources.map do |population, kind, category, names|
       scope = population.scope.except(:select)
-      name = population.definition.expression('name')
       if @params['query'].present?
         pattern = "%#{ ApplicationRecord.sanitize_sql_like(@params['query']) }%"
-        scope = scope.where("(#{ name } LIKE ? OR CAST(v.tag_id AS CHAR) = ? OR EXISTS (" +
+        scope = scope.where("(v.name LIKE ? OR CAST(v.tag_id AS CHAR) = ? OR EXISTS (" +
             "SELECT 1 FROM JSON_TABLE(COALESCE(JSON_EXTRACT(#{ names }, '$**.name'), " +
             "JSON_ARRAY()), '$[*]' COLUMNS (name TEXT PATH '$')) candidate_name " +
             'WHERE candidate_name.name LIKE ?))', pattern, @params['query'], pattern)
       end
       scope.select(Arel.sql(
           "CONCAT('#{ kind }:', v.tag_id) AS value, v.tag_id AS id, " +
-          "#{ name } AS name, #{ names } AS names, " +
-          "#{ category } AS category, '#{ kind }' AS kind"))
+          "v.name AS name, #{ names } AS names, #{ category } AS category, '#{ kind }' AS kind"))
           .to_sql
     end
     clauses = []

backend/app/services/counts_population.rb

@@ -113,7 +113,7 @@ class CountsPopulation
     else
       raise ArgumentError unless definition.axes(history).include?(key)
 
-      scope = scope.where("#{ definition.expression(key) } <=> ?", entry['value'])
+      scope = scope.where(definition.expression(key) => entry['value'])
     end
     scope
   end

backend/app/services/counts_resource_definition.rb

@@ -105,25 +105,12 @@ class CountsResourceDefinition
   def time_column = 'created_at'
   def column(key)
     raise ArgumentError unless fields.key?(key)
-    # Keep the V1 Counts field name at the API boundary only.
-    return 'linked_tag_ids' if resource == 'nico_tags' && key == 'linked_tags'
 
     { 'resource_id' => keys.first, 'user' => 'created_by_user_id' }.fetch(key, key)
   end
 
-  def expression(key, row = 'v')
-    if resource == 'nico_tags' && key == 'name'
-      return "(SELECT CONCAT(external_tags.platform, ':', external_tags.name) " +
-          "FROM external_tags WHERE external_tags.id = #{ row }.tag_id)"
-    end
-
-    "#{ row }.#{ column(key) }"
-  end
-
-  def changes
-    columns = fields.keys - COMMON.keys - ['updated_at', 'updated_by_user_id']
-    resource == 'nico_tags' ? columns - ['name'] : columns
-  end
+  def expression(key, row = 'v') = "#{ row }.#{ column(key) }"
+  def changes = fields.keys - COMMON.keys - ['updated_at', 'updated_by_user_id']
   def axes(history)
     fields.reject { |_key, type| type == :json }.keys +
         (resource == 'posts' ? ['tags'] : []) + (history ? ['changed_field'] : [])
@@ -131,9 +118,7 @@ class CountsResourceDefinition
 
   def metadata
     fields.map do |key, type|
-      nullable = (resource == 'nico_tags' && key == 'name') ||
-          model.columns_hash.fetch(column(key)).null
-      { key:, type:, nullable:,
+      { key:, type:, nullable: model.columns_hash.fetch(column(key)).null,
         operators: OPERATORS.fetch(type, []) }
     end
   end

backend/app/services/counts_state_query.rb

@@ -201,8 +201,6 @@ class CountsStateQuery
   end
 
   def listing
-    external_name = CountsResourceDefinition.new('nico_tags')
-        .expression('name', 'external_version')
     catalog = <<~SQL
       , tag_counts AS (
         SELECT membership.kind, membership.tag_id, COUNT(*) AS post_count
@@ -211,7 +209,7 @@ class CountsStateQuery
         SELECT 'internal' AS kind, tag_id, name, names,
           deprecated_at FROM tag_at WHERE event_type <> 'discard'
         UNION ALL
-        SELECT tc.kind, tc.tag_id, #{ external_name } AS name, JSON_OBJECT() AS names,
+        SELECT tc.kind, tc.tag_id, external_version.name, JSON_OBJECT() AS names,
           NULL AS deprecated_at
         FROM tag_counts tc
         LEFT JOIN tag_at internal_version

backend/app/services/counts_table_query.rb

@@ -182,7 +182,6 @@ class CountsTableQuery
     order = sort_sql { detail_expression(_1) }
     query = query.order(Arel.sql((order + ['v.id ASC']).join(', ')))
         .limit(limit).offset((page - 1) * limit)
-    query = query.preload(:external_tag) if @definition.resource == 'nico_tags'
     rows = query.to_a
     if ['posts', 'tags'].include?(@definition.resource)
       point = population.history ? population.at :
@@ -487,7 +486,6 @@ class CountsTableQuery
 
       table = model.table_name
       scope = HistoryAccess.visible(model.where(tag_id: ids)).where('created_at <= ?', point)
-      scope = scope.includes(:external_tag) if model == NicoTagVersion
       bound = @connection.quote(point)
       if population.history && @definition.resource == 'posts'
         key = kind == 'internal' ? 'tag_id' : 'external_tag_id'

backend/app/services/nico_tag_version_recorder.rb

@@ -1,5 +1,4 @@
 class NicoTagVersionRecorder < VersionRecorder
-  EVENT_TYPES = ['create', 'update'].freeze
   def self.record! external_tag:, event_type:, created_by_user:
     new(external_tag:, event_type:, created_by_user:).record!
   end
@@ -15,7 +14,8 @@ class NicoTagVersionRecorder < VersionRecorder
   def record_key = :external_tag
 
   def snapshot_attributes
-    { linked_tag_ids: @record.snapshot_linked_tag_ids.join(' ') }
+    { name: "#{ @record.platform }:#{ @record.name }",
+      linked_tags: @record.snapshot_linked_tag_names.join(' ') }
   end
 
   def tracks_version_no_on_record? = false

backend/app/services/tag_description_operation.rb

@@ -37,6 +37,37 @@ class TagDescriptionOperation
     end
   end
 
+  def self.update_with_title! locale, tag:, body:, title:, actor:, base_revision_id: nil
+    return update!(locale, tag:, body:, updated_by_user: actor,
+                   base_revision_id:) if title.nil?
+
+    title = title.to_s.strip
+    tag_name = tag.tag_name(locale.language_code)
+    if title.blank? || title.include?(':') || !tag_name || tag_name.name.include?(':')
+      tag.errors.add(:title, :invalid)
+      raise ActiveRecord::RecordInvalid, tag
+    end
+
+    ApplicationRecord.transaction do
+      SharedResourceIdAllocator.lock_space!(Tag, 'tags')
+      tag.lock!
+      old_title = tag_name.name
+      if title != old_title
+        TagVersioning.ensure_snapshot!(tag, created_by_user: actor)
+      end
+
+      tag_name.update!(name: title) if title != old_title
+
+      update!(locale, tag:, body:, updated_by_user: actor,
+              base_revision_id:)
+
+      if title != old_title
+        tag.reload
+        TagVersionRecorder.record!(tag:, event_type: :update, created_by_user: actor)
+      end
+    end
+  end
+
   def self.record_version! description:, body:, user:
     creating = description.new_record?
     version_no = creating ? 1 : description.version_no + 1

backend/config/routes.rb

@@ -17,7 +17,11 @@ Rails.application.routes.draw do
   resources :locales, only: [:index]
   resources :sitemap_entries, only: [:index, :show], param: :resource
 
-  resources :tag_groups, only: [:index, :show, :create, :update]
+  resources :tag_groups, only: [:index, :show, :create, :update] do
+    collection do
+      get 'name/:name', action: :show_by_name
+    end
+  end
 
   resources :nico_tags, path: 'tags/nico', only: [:index, :show, :update]
 
@@ -28,6 +32,9 @@ Rails.application.routes.draw do
 
   resources :tags, only: [:index, :show] do
     collection do
+      get :descriptions, to: 'tag_descriptions#index'
+      post :descriptions, to: 'tag_descriptions#create'
+      get 'descriptions/:description_id', to: 'tag_descriptions#show_by_id'
       get :autocomplete
       get :'with-depth', action: :with_depth
       get :versions, to: 'tag_versions#index'

backend/db/migrate/20261108000000_add_linked_tag_ids_to_nico_tag_versions.rb

@@ -1,5 +0,0 @@
-class AddLinkedTagIdsToNicoTagVersions < ActiveRecord::Migration[8.0]
-  def change
-    add_column :nico_tag_versions, :linked_tag_ids, :text
-  end
-end

backend/db/migrate/20261108010000_migrate_linked_tags_in_nico_tag_versions.rb

@@ -1,42 +0,0 @@
-class MigrateLinkedTagsInNicoTagVersions < ActiveRecord::Migration[8.0]
-  class MigrationTagVersion < ActiveRecord::Base
-    self.table_name = 'tag_versions'
-  end
-
-  class MigrationNicoTagVersion < ActiveRecord::Base
-    self.table_name = 'nico_tag_versions'
-  end
-
-  def up
-    # 除票外部タグの恢復はないので除票履歴があれば全消しでよいはず．
-    execute <<~SQL
-      DELETE
-        t1
-      FROM
-        nico_tag_versions t1
-        INNER JOIN
-          nico_tag_versions t2
-          ON
-            t1.tag_id = t2.tag_id
-            AND t2.event_type = 'discard'
-    SQL
-
-    MigrationNicoTagVersion.find_each do |ntv|
-      linked_tag_ids = ntv.linked_tags.split.map { |name|
-        # 厳密には一意ぢゃないけどめんだぅだからこれでいいや．
-        MigrationTagVersion
-            .order(created_at: :desc, id: :desc)
-            .find_by("names ->> '$.ja.name' = ?", name)
-            &.tag_id
-      }.compact.uniq.sort.join(' ')
-
-      ntv.update_columns(linked_tag_ids:)
-    end
-
-    change_column_null :nico_tag_versions, :linked_tag_ids, false
-  end
-
-  def down
-    raise ActiveRecord::IrreversibleMigration, '戻せません．'
-  end
-end

backend/db/migrate/20261108020000_remove_linked_tags_from_nico_tag_versions.rb

@@ -1,6 +0,0 @@
-class RemoveLinkedTagsFromNicoTagVersions < ActiveRecord::Migration[8.0]
-  def change
-    remove_column :nico_tag_versions, :linked_tags
-    remove_column :nico_tag_versions, :name
-  end
-end

backend/db/migrate/20261116000000_add_index_to_tags_post_count.rb

@@ -1,5 +0,0 @@
-class AddIndexToTagsPostCount < 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_16_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
@@ -301,9 +301,10 @@ ActiveRecord::Schema[8.0].define(version: 2026_11_16_000000) do
     t.bigint "tag_id", null: false
     t.integer "version_no", null: false
     t.string "event_type", null: false
+    t.string "name", null: false
+    t.text "linked_tags", null: false
     t.datetime "created_at", null: false
     t.bigint "created_by_user_id"
-    t.text "linked_tag_ids", null: false
     t.index ["created_at"], name: "index_nico_tag_versions_on_created_at"
     t.index ["created_by_user_id", "created_at"], name: "index_nico_tag_versions_on_created_by_user_id_and_created_at", order: { created_at: :desc }
     t.index ["tag_id", "created_at"], name: "index_nico_tag_versions_on_tag_id_and_created_at", order: { created_at: :desc }
@@ -629,7 +630,6 @@ ActiveRecord::Schema[8.0].define(version: 2026_11_16_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/external_tag_spec.rb

@@ -11,63 +11,28 @@ RSpec.describe ExternalTag, type: :model do
     expect(external.reload.name).to eq('raw tag[]')
   end
 
-  it 'does not allow a persisted external tag to change its platform or name' do
-    external = create(:external_tag, name: 'immutable')
-
-    expect { external.update!(name: 'renamed') }
-        .to raise_error(ActiveRecord::RecordInvalid)
-    expect(external.errors[:name]).to include('は変更できません．')
-
-    external.reload
-    external.platform = nil
-    expect { external.save! }.to raise_error(ActiveRecord::RecordInvalid)
-    expect(external.errors[:platform]).to include('は変更できません．')
-
-    expect(external.reload).to have_attributes(platform: 'nico', name: 'immutable')
-  end
-
-  it 'rejects delete, which bypasses destroy callbacks' do
-    external = create(:external_tag)
-
-    expect { external.delete }.to raise_error(ActiveRecord::ReadOnlyRecord)
-    expect(external.reload).to be_persisted
-  end
-
-  it 'increments the counter through post associations without changing identity' do
-    external = create(:external_tag, name: 'counter')
-    post = create(:post)
-
-    expect {
-      PostExternalTag.create!(post:, external_tag: external)
-    }.to change { external.reload.post_count }.by(1)
-
-    expect(external.reload).to have_attributes(platform: 'nico', name: 'counter')
-  end
-
-  it 'does not destroy external tags or their post associations and history' do
+  it 'deletes post associations without deleting posts or version history' do
     external = create(:external_tag)
     post = create(:post)
     PostExternalTag.create!(post:, external_tag: external)
     version = NicoTagVersionRecorder.record!(
         external_tag: external, event_type: :create, created_by_user: nil)
 
-    expect { external.destroy! }.to raise_error(ActiveRecord::RecordNotDestroyed)
+    external.destroy!
 
-    expect(external.reload).to be_persisted
-    expect(PostExternalTag.exists?(post:, external_tag: external)).to be(true)
-    expect(post.reload.external_tags).to contain_exactly(external)
+    expect(PostExternalTag.where(external_tag_id: external.id)).to be_empty
+    expect(post.reload.external_tags).to be_empty
     expect(version.reload.tag_id).to eq(external.id)
   end
 
-  it 'does not destroy an external tag or its links to internal tags' do
+  it 'deletes external links without deleting linked internal tags' do
     external = create(:external_tag)
     tag = create(:tag)
-    relation = NicoTagRelation.create!(nico_tag: external, tag:)
+    NicoTagRelation.create!(nico_tag: external, tag:)
 
-    expect { external.destroy! }.to raise_error(ActiveRecord::RecordNotDestroyed)
+    external.destroy!
 
-    expect(external.reload).to be_persisted
-    expect(relation.reload).to be_persisted
+    expect(NicoTagRelation.where(nico_tag_id: external.id)).to be_empty
     expect(Tag.exists?(tag.id)).to be(true)
   end
 end

backend/spec/models/history_access_spec.rb

@@ -76,7 +76,7 @@ RSpec.describe 'Counts artifact policy and external references' do
     end
   end
 
-  it 'does not expose a private linked tag ID through an external history snapshot' do
+  it 'does not expose a private linked tag name through an external history snapshot' do
     tag = create(:tag, primary_name: 'private-linked-name')
     TagVersion.create!(tag:, version_no: 1, event_type: 'discard', name: 'private-linked-name',
         category: 'general', aliases: '', parent_tag_ids: '', created_at: Time.utc(2024),
@@ -84,7 +84,7 @@ RSpec.describe 'Counts artifact policy and external references' do
                        auto_generated: false, aliases: [] } })
     external = create(:external_tag, name: 'public-external')
     row = NicoTagVersion.create!(external_tag: external, version_no: 1, event_type: 'create',
-        linked_tag_ids: tag.id.to_s,
+        name: 'nico:public-external', linked_tags: 'private-linked-name',
         created_at: Time.utc(2024))
     post = create(:post)
     snapshot = PostVersion.create!(post:, version_no: 1, event_type: 'create',
@@ -99,7 +99,7 @@ RSpec.describe 'Counts artifact policy and external references' do
       expect(HistoryAccess.visible(NicoTagVersion.where(id: row.id))).to exist
     end
     public_row = NicoTagVersion.create!(external_tag: external, version_no: 2, event_type: 'update',
-        linked_tag_ids: '',
+        name: 'nico:public-external', linked_tags: 'private-linked-name-extra',
         created_at: Time.utc(2024, 7))
     HistoryAccess.set(user: nil) do
       expect(HistoryAccess.visible(NicoTagVersion.where(id: public_row.id))).to exist

backend/spec/models/shared_tag_ids_spec.rb

@@ -10,22 +10,23 @@ RSpec.describe 'Shared Tag and ExternalTag IDs', type: :model do
     expect(next_tag.id).to be > external.id
   end
 
-  it 'does not reuse IDs after internal deletion while external tags remain' do
+  it 'does not reuse physically deleted IDs in either table' do
     tag = create(:tag)
     external = create(:external_tag)
     TagName.where(tag_id: tag.id).delete_all
     tag.destroy!
-    expect(ExternalTag.exists?(external.id)).to be(true)
+    external.destroy!
 
     expect(create(:tag).id).to be > external.id
     expect(create(:external_tag).id).to be > external.id
   end
 
-  it 'retains overlapping IDs after a tag update and a new allocation' do
+  it 'retains existing overlapping IDs without renumbering on update or insert' do
     tag = create(:tag)
     external = create(:external_tag)
     external.update_columns(id: tag.id)
     tag.update!(category: :meta)
+    external.update!(name: 'updated_external')
     before_tag = tag.reload.attributes
     before_external = external.reload.attributes
 

backend/spec/models/tag_spec.rb

@@ -2,17 +2,6 @@ require 'rails_helper'
 
 RSpec.describe Tag, type: :model do
   include WikiRecords
-
-  describe 'database indexes' do
-    it 'has a non-unique index on post_count' do
-      indexes = described_class.connection.indexes(described_class.table_name)
-      index = indexes.find { |entry| entry.columns == ['post_count'] }
-
-      expect(index).to be_present
-      expect(index.unique).to be(false)
-    end
-  end
-
   describe '#has_description?' do
     let(:tag) { create(:tag) }
 

backend/spec/models/version_record_spec.rb

@@ -47,34 +47,24 @@ RSpec.describe VersionRecord, type: :model do
       external_tag: nico_tag,
       version_no: 1,
       event_type: 'create',
-      linked_tag_ids: '',
+      name: "nico:#{ nico_tag.name }",
+      linked_tags: '',
       created_at: Time.current,
       created_by_user: nil
     )
 
     expect {
-      version.update!(linked_tag_ids: '123')
+      version.update!(name: 'nico:changed')
     }.to raise_error(ActiveRecord::ReadOnlyRecord)
   end
 
-
-  it 'rejects discard and restore versions for external tags' do
-    [:discard, :restore].each do |event_type|
-      version = NicoTagVersion.new(
-          external_tag: nico_tag, version_no: 1, event_type:,
-          linked_tag_ids: '', created_at: Time.current)
-
-      expect(version).not_to be_valid
-      expect(version.errors[:event_type]).not_to be_empty
-    end
-  end
-
   it 'prevents NicoTagVersion destroy' do
     version = NicoTagVersion.create!(
       external_tag: nico_tag,
       version_no: 1,
       event_type: 'create',
-      linked_tag_ids: '',
+      name: "nico:#{ nico_tag.name }",
+      linked_tags: '',
       created_at: Time.current,
       created_by_user: nil
     )

backend/spec/requests/counts_table_spec.rb

@@ -19,7 +19,7 @@ RSpec.describe 'Counts table API', type: :request do
         names: { ja: { name: 'alpha', script_code: 'Jpan', auto_generated: false,  aliases: [] } },
         created_at: Time.utc(2023))
     NicoTagVersion.create!(external_tag: external, version_no: 1,
-        event_type: 'create', linked_tag_ids: '', created_at: Time.utc(2023))
+        event_type: 'create', name: 'beta', linked_tags: '', created_at: Time.utc(2023))
     snapshots = [
         { tag_id: tag.id, version_no: 1, name: 'alpha', category: 'general', sections: [] },
         { external_tag_id: external.id }]
@@ -50,115 +50,6 @@ RSpec.describe 'Counts table API', type: :request do
 
   def versions(result) = result.fetch('versions').map { _1.fetch('version_no') }
 
-  context 'nico link ID snapshots through the V1 field name' do
-    let(:base) do
-      super().merge(resource: 'nico_tags')
-    end
-
-    before do
-      NicoTagVersion.create!(external_tag: external, version_no: 2,
-          event_type: 'update', linked_tag_ids: tag.id.to_s,
-          created_at: Time.utc(2024, 1, 1))
-      NicoTagVersion.create!(external_tag: external, version_no: 3,
-          event_type: 'update', linked_tag_ids: '',
-          created_at: Time.utc(2024, 2, 1))
-    end
-
-    it 'returns ID values under linked_tags without exposing the physical column key' do
-      result = query
-      expect(versions(result)).to eq([1, 2, 3])
-      expect(result['versions'].map { _1.fetch('linked_tags') }).to eq(['', tag.id.to_s, ''])
-      result['versions'].each do |row|
-        expect(row).not_to have_key('linked_tag_ids')
-        expect(row.fetch('name')).to eq('nico:beta')
-      end
-    end
-
-    it 'preloads external names separately for aliased link-change details' do
-      statements = []
-      listener = lambda do |_name, _start, _finish, _id, payload|
-        statements << payload[:sql]
-      end
-      ActiveSupport::Notifications.subscribed(listener, 'sql.active_record') do
-        result = query(axis('changed_field', 'linked_tags'))
-        expect(versions(result)).to eq([2, 3])
-        expect(result.fetch('versions').map { _1.fetch('name') })
-            .to eq(['nico:beta', 'nico:beta'])
-      end
-
-      details = statements.find { _1.include?('AS counts_latest') }
-      expect(details).not_to be_nil
-      expect(details).not_to include('JOIN `external_tags`')
-      names = statements.select { _1.match?(/SELECT .* FROM `external_tags`/) }
-      expect(names.length).to eq(1)
-    end
-
-    it 'advertises the legacy field, label and default columns only' do
-      get '/counts/definitions/nico_tags', params: { locale: 'ja' }
-      expect(response).to have_http_status(:ok)
-      body = response.parsed_body
-      ['fields', 'filter_fields', 'output_fields'].each do |collection|
-        keys = body.fetch(collection).map { _1.fetch('key') }
-        expect(keys).to include('linked_tags')
-        expect(keys).not_to include('linked_tag_ids')
-      end
-      field = body.fetch('output_fields').find { _1['key'] == 'linked_tags' }
-      expect(field.fetch('label')).to eq('counts:attributes.linked_tags')
-      body.fetch('axes').each_value do |keys|
-        expect(keys).to include('linked_tags')
-        expect(keys).not_to include('linked_tag_ids')
-      end
-      body.fetch('defaults').select { _1['mode'] == 'details' }.each do |entry|
-        settings = entry.fetch('params').to_h { [_1.fetch('key'), _1.fetch('value')] }
-        expect(settings.fetch('columns').split).to include('name', 'linked_tags')
-        expect(settings.fetch('columns').split).not_to include('linked_tag_ids')
-      end
-    end
-
-    it 'filters IDs and legacy drills and compares link changes through linked_tags' do
-      predicate = { conditions: '', 'conditions.0.field' => 'linked_tags',
-                    'conditions.0.operator' => 'eq', 'conditions.0.value' => tag.id.to_s }
-      expect(versions(query(predicate))).to eq([2])
-      expect(versions(query(axis('linked_tags', tag.id.to_s, root: 'drill')))).to eq([2])
-      expect(versions(query(axis('changed_field', 'linked_tags')))).to eq([2, 3])
-      expect(versions(query(predicate.merge('conditions.0.value' => 'alpha')))).to be_empty
-    end
-
-    it 'sorts ID snapshots through the public field in both directions' do
-      expect(versions(query(sort: 'linked_tags:asc version_no:asc'))).to eq([1, 3, 2])
-      expect(versions(query(sort: 'linked_tags:desc version_no:asc'))).to eq([2, 1, 3])
-    end
-
-    it 'restores historical link IDs before applying a latest snapshot filter' do
-      predicate = { definition: 'latest', at: '2024-01-15T00:00:00Z',
-                    conditions: '', 'conditions.0.field' => 'linked_tags',
-                    'conditions.0.operator' => 'eq', 'conditions.0.value' => tag.id.to_s }
-      expect(versions(query(predicate))).to eq([2])
-      expect(versions(query(predicate.except(:at)))).to be_empty
-    end
-
-    it 'groups by linked_tags ID values and accepts the resulting drill condition' do
-      sign_in_as(create(:user, :admin))
-      result = query(mode: 'summary', rows: 'linked_tags', cols: '', sort: '')
-      expect(result.fetch('cells')).to match_array([
-          { 'values' => [''], 'count' => 2 },
-          { 'values' => [tag.id.to_s], 'count' => 1 }])
-      expect(versions(query(axis('linked_tags', tag.id.to_s)))).to eq([2])
-    end
-
-    it 'rejects the physical column as a public filter, axis, sort or change field' do
-      sign_in_as(create(:user, :admin))
-      [
-          axis('linked_tag_ids', tag.id.to_s),
-          axis('changed_field', 'linked_tag_ids'),
-          { mode: 'summary', rows: 'linked_tag_ids', cols: '', sort: '' },
-          { sort: 'linked_tag_ids:asc' }].each do |invalid|
-        get '/counts/query', params: base.merge(invalid)
-        expect(response).to have_http_status(:bad_request), invalid.inspect
-      end
-    end
-  end
-
   it 'identifies a totals timeout without exposing SQL in the error response' do
     allow_any_instance_of(CountsPivotTotals).to receive(:call)
         .and_raise(CountsPivotTotals::TimedOut, 'private SQL')
@@ -332,10 +223,11 @@ RSpec.describe 'Counts table API', type: :request do
       expect(versions(query(tags: 'renamed-alpha'))).to eq([1, 2, 4])
     end
 
-    it 'resolves immutable external names across historical snapshots' do
-      expect(versions(query(tags: 'nico:beta'))).to eq([1])
-      expect(versions(query(tags: 'nico:renamed-beta'))).to eq([])
-      expect(versions(query(tags: 'not:nico:beta'))).to eq([2, 3, 4])
+    it 'resolves external names from current registrations too' do
+      external.update!(name: 'renamed-beta')
+      expect(versions(query(tags: 'nico:renamed-beta'))).to eq([1])
+      expect(versions(query(tags: 'nico:beta'))).to eq([])
+      expect(versions(query(tags: 'not:nico:renamed-beta'))).to eq([2, 3, 4])
     end
   end
 

backend/spec/requests/nico_tags_spec.rb

@@ -38,9 +38,12 @@ RSpec.describe 'NicoTags', type: :request do
     end
 
     it 'filters by nico tag name, linked tag name, and link status' do
-      linked = create(:external_tag, name: 'search_linked')
-      unlinked = create(:external_tag, name: 'search_unlinked')
-      other = create(:external_tag, name: 'other')
+      linked = create(:external_tag)
+      linked.update!(name: 'search_linked')
+      unlinked = create(:external_tag)
+      unlinked.update!(name: 'search_unlinked')
+      other = create(:external_tag)
+      other.update!(name: 'other')
       destination = create(:tag, category: :general)
       primary_tag_name_for(destination, 'ja').update!(name: 'destination_search')
       NicoTagRelation.create!(nico_tag: linked, tag: destination)
@@ -77,9 +80,11 @@ RSpec.describe 'NicoTags', type: :request do
     end
 
     it 'sorts by name and timestamps' do
-      older = create(:external_tag, name: 'ordered_a')
+      older = create(:external_tag)
+      older.update!(name: 'ordered_a')
       older.update_columns(created_at: 2.days.ago)
-      newer = create(:external_tag, name: 'ordered_b')
+      newer = create(:external_tag)
+      newer.update!(name: 'ordered_b')
       newer.update_columns(created_at: 1.day.ago)
       older_post_tag =
         PostExternalTag.create!(post: create(:post), external_tag: older)
@@ -184,8 +189,9 @@ RSpec.describe 'NicoTags', type: :request do
 
       versions = nico_tag.reload.nico_tag_versions.order(:version_no)
       expect(versions.map(&:event_type)).to eq(['create', 'update'])
-      expect(versions.last.linked_tag_ids.split.map(&:to_i))
-          .to match_array([linked_a.id, linked_b.id])
+      expect(versions.last.linked_tags.split).to match_array([
+        'nico_linked_a',
+        'nico_linked_b'])
       expect(versions.last.created_by_user_id).to eq(admin.id)
     end
 
@@ -204,7 +210,7 @@ RSpec.describe 'NicoTags', type: :request do
       expect(json).to eq([])
       expect(nico_tag.reload.linked_tags).to be_empty
       expect(nico_tag.nico_tag_versions.order(:version_no).last)
-          .to have_attributes(linked_tag_ids: '', created_by_user: member)
+          .to have_attributes(linked_tags: '', created_by_user: member)
     end
 
     it 'returns the tags field error when a nico tag is specified directly' do

backend/spec/requests/post_history_privacy_spec.rb

@@ -20,7 +20,7 @@ RSpec.describe 'Post history privacy', type: :request do
           created_at: origin + index.hours)
     end
     NicoTagVersion.create!(external_tag: external, version_no: 1, event_type: 'create',
-        linked_tag_ids: tag.id.to_s,
+        name: 'nico:external-history-tag', linked_tags: 'private-history-tag',
         created_at: origin)
     ['create', 'discard', 'restore', 'update'].each_with_index do |event, index|
       snapshots =

backend/spec/services/counts_export_spec.rb

@@ -22,55 +22,6 @@ RSpec.describe 'Counts export contracts' do
         .and_return(@counts_export_dir)
   end
 
-  context 'nico link IDs with the V1 export field name' do
-    let(:tag) { create(:tag, primary_name: 'linked export tag') }
-    let(:external) { create(:external_tag, name: 'external export tag') }
-    let(:payload) do
-      super().merge('resource' => 'nico_tags', 'columns' => 'linked_tags',
-          'headers' => '["linked_tags"]')
-    end
-
-    before do
-      NicoTagVersion.create!(external_tag: external, version_no: 1,
-          event_type: 'create', linked_tag_ids: '', created_at: Time.utc(2023))
-      NicoTagVersion.create!(external_tag: external, version_no: 2,
-          event_type: 'update', linked_tag_ids: tag.id.to_s, created_at: Time.utc(2024))
-    end
-
-    it 'exports recorded IDs with the legacy JSON key and metadata' do
-      result = JSON.parse(CountsTableExport.new(payload).body.to_a.join)
-      expect(result.fetch('data')).to eq([
-          { 'linked_tags' => '' }, { 'linked_tags' => tag.id.to_s }])
-      expect(result.fetch('metadata').fetch('columns')).to eq(['linked_tags'])
-      keys = result.fetch('metadata').fetch('fields').map { _1.fetch('key') }
-      expect(keys).to include('linked_tags')
-      expect(keys).not_to include('linked_tag_ids')
-    end
-
-    it 'exports the selected legacy CSV header and ID values' do
-      body = CountsTableExport.new(payload.merge('format' => 'csv')).body.to_a.join
-      expect(CSV.parse(body.delete_prefix("\uFEFF")))
-          .to eq([['linked_tags'], [''], [tag.id.to_s]])
-    end
-
-    it 'keeps the legacy link column in default JSON exports' do
-      options = payload.except('columns', 'headers')
-      result = JSON.parse(CountsTableExport.new(options).body.to_a.join)
-      expect(result.fetch('metadata').fetch('columns')).to include('linked_tags')
-      result.fetch('data').each do |row|
-        expect(row).to have_key('linked_tags')
-        expect(row).not_to have_key('linked_tag_ids')
-      end
-    end
-
-    it 'rejects the physical column as a selected CSV or JSON field' do
-      ['csv', 'json'].each do |format|
-        options = payload.merge('format' => format, 'columns' => 'linked_tag_ids')
-        expect { CountsTableExport.new(options) }.to raise_error(ArgumentError)
-      end
-    end
-  end
-
   context 'serialization after the authorised query' do
     let(:rows) { [{ title: "=formula\n\"quoted\"" }, { title: 'second' }] }
     let(:page) do

backend/spec/services/nico_tag_version_recorder_spec.rb

@@ -8,23 +8,21 @@ RSpec.describe NicoTagVersionRecorder do
     described_class.record!(external_tag:, event_type:, created_by_user: member)
   end
 
-  it 'records the external association and derives the platform-qualified name' do
+  it 'records the external association and platform-qualified name' do
     version = record(:create)
 
     expect(version).to have_attributes(
         external_tag:, version_no: 1, event_type: 'create',
-        name: 'nico:raw tag[]', linked_tag_ids: '', created_by_user: member)
+        name: 'nico:raw tag[]', linked_tags: '', created_by_user: member)
     expect(external_tag.reload.nico_tag_versions).to contain_exactly(version)
   end
 
   it 'uses the latest history number when the record has no version_no column' do
     first = record(:create)
-    tag = create(:tag)
-    NicoTagRelation.create!(nico_tag: external_tag, tag:)
+    external_tag.update!(name: 'changed')
     second = record(:update)
 
-    expect(second).to have_attributes(version_no: 2, name: 'nico:raw tag[]',
-        linked_tag_ids: tag.id.to_s)
+    expect(second).to have_attributes(version_no: 2, name: 'nico:changed')
     expect(first.reload.name).to eq('nico:raw tag[]')
     expect(external_tag.reload.has_attribute?(:version_no)).to be(false)
   end
@@ -42,7 +40,7 @@ RSpec.describe NicoTagVersionRecorder do
 
     expect(version).to have_attributes(
         external_tag: external, name: 'registered_external:foo', version_no: 1,
-        event_type: 'create', linked_tag_ids: '', created_by_user: member)
+        event_type: 'create', linked_tags: '', created_by_user: member)
   end
 
   it 'returns the latest version without appending an unchanged snapshot' do
@@ -66,21 +64,13 @@ RSpec.describe NicoTagVersionRecorder do
     expect(external_tag.nico_tag_versions).to contain_exactly(first)
   end
 
-
-  it 'rejects discard and restore events for external tags' do
-    [:discard, :restore].each do |event_type|
-      expect { record(event_type) }
-          .to raise_error(ArgumentError, "Invalid event_type: #{ event_type }")
-    end
-  end
-
-  it 'records sorted linked internal IDs and later link removal' do
+  it 'records sorted linked internal names and later link removal' do
     tags = ['z_link', 'a_link'].map { |name| create(:tag, primary_name: name, category: :general) }
     tags.each { |tag| NicoTagRelation.create!(nico_tag: external_tag, tag:) }
 
-    expect(record(:create).linked_tag_ids).to eq(tags.map(&:id).sort.join(' '))
+    expect(record(:create).linked_tags).to eq('a_link z_link')
     external_tag.linked_tags = [tags.first]
 
-    expect(record(:update)).to have_attributes(version_no: 2, linked_tag_ids: tags.first.id.to_s)
+    expect(record(:update)).to have_attributes(version_no: 2, linked_tags: 'z_link')
   end
 end

docs/counts-exports.md

@@ -158,15 +158,7 @@ private ID の正誤に応じて許可可否を変えないため、条件の一
 非公開列を含む列順変更は API の column_values_editable でも不可と通知する。
 公開列の値を使うソートは引き続き利用できる。
 明細には元の認可を適用し、抽出条件自体や取得済みの全言語値を表示設定で改変しない。
-外部タグ履歴の linked_tag_ids は、連携する内部タグの ID を半角スペース区切りで
-記録する。除票履歴のある内部タグの ID を含むスナップショットを非管理者へ公開しない。
-名前や UI ロカールを参照 ID の判定に使わない。
-外部タグ名は履歴に保存せず、external_tags の platform と name を参照する。
-
-V1 Counts の公開フィールド名は linked_tags を維持し、DB の linked_tag_ids へ対応付ける。
-明細・フィルタ・集計軸・変更項目・ソート・CSV / JSON 出力で同じ対応付けを使う。
-既定列と既存の表示ラベルも linked_tags のままとし、値は ID のスペース区切りとする。
-linked_tag_ids は物理カラム名であり、Counts の公開フィールドとしては受け付けない。
-旧 URL や保存済み設定のフィールド指定は維持できるが、値にタグ名を指定した検索条件や
-ドリル条件は ID 値への見直しが必要となる。旧履歴の名称は移行後の ID 列から復元できず、
-現在の名称からの推定変換も行わない。
+外部タグ履歴の linked_tags は名前しか記録していないため、非公開タグの記録名を含む
+スナップショットを保守的に非公開とする。名前全体を空白区切りの境界で照合する。
+区切りが曖昧な旧データでは過剰な秘匿の可能性はあるが、参照 ID がない旧形式から
+名前の公開可否を楽観的に推定しない。

frontend/src/App.tsx

@@ -166,7 +166,12 @@ export const pageRoutes = (
 	    robots: 'noindex', authentication: 'user' } },
 	{ path: ':id', element: <MaterialDetailPage/>,
 	  handle: { preload: MaterialDetailPage.preload, sitemap: ['materials'] } }] },
-    { path: 'wiki', element: <WikiSearchPage/>,
+    { path: 'wiki', element: <LocaleRedirect to="/tags"/>,
+      handle: { redirectTo: '/tags' } },
+    { path: 'tag-descriptions', element: <LocaleRedirect to="/tags"/>,
+      handle: { redirectTo: '/tags' } },
+    { path: 'tag-groups',
+      element: <WikiSearchPage key="tag_group" resourceType="tag_group"/>,
       handle: { preload: WikiSearchPage.preload, sitemap: ['static'] } },
     { path: 'wiki/:title', element: <WikiDetailPage/>,
       handle: { preload: WikiDetailPage.preload, switchLocale: switchWikiLocale,

frontend/src/components/TopNav.tsx

@@ -29,7 +29,7 @@ import { fetchWikiPage } from '@/lib/wiki'
 import type { FC, MouseEvent } from 'react'
 
 import type { AvailableLocale, LocaleCode } from '@/lib/locales'
-import type { Material, Menu, MenuVisibleItem, Tag, User } from '@/types'
+import type { Material, Menu, MenuVisibleItem, Tag, User, WikiPage } from '@/types'
 
 type Props = {
     user: User | null
@@ -39,10 +39,11 @@ type NavDensity = 'auto' | 'comfortable' | 'compact'
 
 
 export const menuOutline = (
-    { tag, material, wikiId, user, pathName: fullPathname }: {
+    { tag, material, wikiId, wikiResourceType, user, pathName: fullPathname }: {
 	tag?: Tag | null
 	material?: Material | null
 	wikiId: number | null
+	wikiResourceType?: WikiPage['resourceType']
 	user: User | null
 	pathName: string },
 ): Menu => {
@@ -99,17 +100,29 @@ export const menuOutline = (
 	    visible: materialFlg && Boolean (material?.tag) },
 	  { ...message ('history'), to: `/materials/changes?material_id=${ material?.id }`,
 	    visible: materialFlg }] },
-      { ...message ('wiki'), to: '/wiki', subMenu: [
-	  { ...message ('search'), to: '/wiki' },
-	  { ...message ('create'), to: '/wiki/new', visible: editable },
-	  { ...message ('allHistory'), to: '/wiki/changes' },
-	  { ...message ('help'), to: '/wiki/ヘルプ:Wiki' },
-	  { component: <Separator/>, visible: wikiPageFlg },
-	  { ...message ('postsWithCount', { count: postCount }), to: `/posts?tags=${ wikiTitle }`,
-	    visible: wikiPageFlg },
-	  { ...message ('history'), to: `/wiki/changes?id=${ wikiId }`, visible: wikiPageFlg },
-	  { ...message ('edit'), to: `/wiki/${ wikiId || wikiTitle }/edit`,
-	    visible: wikiPageFlg && editable }] },
+      ...([
+	  { key: 'tagGroups', path: '/tag-groups', type: 'tag_group' }] as const)
+	  .map (({ key, path, type }): MenuVisibleItem => {
+	    const current = (wikiResourceType ?? 'tag_description') === type
+	    const detailFlg = wikiPageFlg && current
+	    const creationPath =
+		type === 'tag_group'
+		? `/wiki/new?title=${ encodeURIComponent ('タググループ:') }` : '/wiki/new'
+	    return { ...message (key), to: path,
+		base: (pathName.startsWith ('/wiki') && current) ? '/wiki' : path,
+		subMenu: [
+		    { ...message ('search'), to: path },
+		    { ...message ('create'), to: creationPath, visible: editable },
+		    { ...message ('allHistory'), to: '/wiki/changes' },
+		    { ...message ('help'), to: '/wiki/ヘルプ:Wiki' },
+		    { component: <Separator/>, visible: detailFlg },
+		    { ...message ('postsWithCount', { count: postCount }),
+		      to: `/posts?tags=${ wikiTitle }`, visible: detailFlg },
+		    { ...message ('history'), to: `/wiki/changes?id=${ wikiId }`,
+		      visible: detailFlg },
+		    { ...message ('edit'), to: `/wiki/${ wikiId || wikiTitle }/edit`,
+		      visible: detailFlg && editable }] }
+	  }),
       { ...message ('help'), to: '/help/home', base: '/help', subMenu: [
 	  { ...message ('search'), to: '/help' },
 	  { ...message ('allHistory'), to: '/help/changes' },
@@ -229,7 +242,8 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
       queryKey: materialsKeys.show (effectiveTitle, locale),
       queryFn: () => fetchMaterial (effectiveTitle, locale) })
 
-  const menu = menuOutline ({ tag, material, wikiId, user, pathName: location.pathname })
+  const menu = menuOutline ({ tag, material, wikiId,
+      wikiResourceType: wikiPage?.resourceType, user, pathName: location.pathname })
   const visibleMenu = menu.filter ((item): item is MenuVisibleItem => item.visible ?? true)
   const menuLabels = visibleMenu.map (item => item.name).join ('\u0000')
   const moreMenu = menu.filter (item =>

frontend/src/lib/prefetchers.ts

@@ -100,10 +100,11 @@ const prefetchHelpDiff: Prefetcher = async (qc, url, locale) => {
 
 const prefetchWikiPagesIndex: Prefetcher = async (qc, url, locale) => {
   const title = url.searchParams.get ('title') ?? ''
+  const resourceType = 'tag_group'
 
   await qc.prefetchQuery ({
-      queryKey: wikiKeys.index ({ title }, locale),
-      queryFn:  () => fetchWikiPages ({ title }, locale) })
+      queryKey: wikiKeys.index ({ title, resourceType }, locale),
+      queryFn: () => fetchWikiPages ({ title, resourceType }, locale) })
 }
 
 
@@ -310,7 +311,8 @@ export const routePrefetchers: { test: (u: URL) => boolean; run: Prefetcher }[]
 		  && Boolean (mPost (u.pathname))),
       run: prefetchPostShow },
     { test: u => u.pathname === '/posts/changes', run: prefetchPostChanges },
-    { test: u => u.pathname === '/wiki', run: prefetchWikiPagesIndex },
+    { test: u => u.pathname === '/tag-groups',
+      run: prefetchWikiPagesIndex },
     { test: u => (!(['/wiki/new', '/wiki/changes'].includes (u.pathname))
 		  && Boolean (mWiki (u.pathname))),
       run: prefetchWikiPageShow },

frontend/src/lib/queryKeys.ts

@@ -5,6 +5,7 @@ import type {
     FetchPostsParams,
     FetchTagsParams,
     MaterialFilter,
+    WikiPage,
     WikiTagReference } from '@/types'
 
 export const localesKeys = {
@@ -130,7 +131,7 @@ export const wikiKeys = {
     autolinkCandidates: (language: string, locale: LocaleCode) =>
 	['wiki', 'autolink', locale, language] as const,
     index:  (
-    p: { title?: string },
+    p: { title?: string, resourceType?: WikiPage['resourceType'] },
     locale: LocaleCode = 'ja',
 ) => ['wiki', locale, 'index', p] as const,
     show:   (

frontend/src/lib/wiki.ts

@@ -1,6 +1,6 @@
 import { isAxiosError } from 'axios'
 
-import { apiGet } from '@/lib/api'
+import { apiGet, apiPost, apiPut } from '@/lib/api'
 import { switchLocalePath } from '@/lib/locales'
 import { fetchTag, fetchTagByName } from '@/lib/tags'
 
@@ -24,19 +24,54 @@ export const fetchWikiChanges = (
 
 
 export const fetchWikiPages = async (
-    { title }:  { title?: string },
+    { title, resourceType = 'tag_description' }: {
+	title?: string, resourceType?: WikiPage['resourceType'] },
     locale: LocaleCode = 'ja',
-): Promise<WikiPage[]> =>
-    await apiGet ('/wiki', { locale, params: { title } })
+): Promise<WikiPage[]> => apiGet (
+    resourceType === 'tag_group' ? '/tag_groups' : '/tags/descriptions',
+    { locale, params: { title, document: '1' } })
 
 
 export const fetchWikiPage = async (
-    id:           string,
-    { version }:  { version?: string },
+    id: string,
+    { version }: { version?: string },
     locale: LocaleCode = 'ja',
-): Promise<WikiPage> =>
-    await apiGet (`/wiki/${ encodeURIComponent (id) }`, {
-	locale, params: version ? { version } : { } })
+): Promise<WikiPage> => {
+  if (version != null)
+    return apiGet (`/wiki/${encodeURIComponent (id)}`, { locale, params: { version } })
+  try
+  {
+    return await apiGet (`/tags/descriptions/${encodeURIComponent (id)}`,
+	{ locale, params: { document: '1' } })
+  }
+  catch (error)
+  {
+    if (!isAxiosError (error) || error.response?.status !== 404)
+      throw error
+    return apiGet (`/tag_groups/${encodeURIComponent (id)}`,
+	{ locale, params: { document: '1' } })
+  }
+}
+
+
+export const saveTagDocument = async (
+    { title, body, page }: { title: string, body: string, page?: WikiPage },
+    locale: LocaleCode,
+): Promise<WikiPage> => {
+  const groupName = /^(?:タググループ:|tag_group:)(.*)$/i.exec (title.trim ())?.[1]
+  const options = { locale, params: { document: '1' } }
+  if (page?.resourceType === 'tag_group' || (page == null && groupName != null))
+  {
+    const attributes = { name: groupName ?? title.trim (), body }
+    return page == null
+	? apiPost ('/tag_groups', attributes, options)
+	: apiPut (`/tag_groups/${encodeURIComponent (String (page.id))}`, attributes, options)
+  }
+  if (page == null)
+    return apiPost ('/tags/descriptions', { title, body }, options)
+  return apiPut (`/tags/${encodeURIComponent (String (page.tagId))}/description`,
+      { title, body }, options)
+}
 
 
 export const fetchWikiPageByTitle = async (
@@ -46,7 +81,14 @@ export const fetchWikiPageByTitle = async (
 ): Promise<WikiPage | null> => {
   try
   {
-    return await apiGet (`/wiki/title/${ encodeURIComponent (title) }`, { locale, params: { version } })
+    if (version != null)
+      return await apiGet (`/wiki/title/${encodeURIComponent (title)}`,
+	  { locale, params: { version } })
+    const groupName = /^(?:タググループ:|tag_group:)(.*)$/i.exec (title.trim ())?.[1]
+    const path = groupName == null
+	? `/tags/name/${encodeURIComponent (title)}/description`
+	: `/tag_groups/name/${encodeURIComponent (groupName)}`
+    return await apiGet (path, { locale, params: { document: '1' } })
   }
   catch (error)
   {
@@ -72,7 +114,7 @@ export const fetchWikiPageByReference = async (
   {
     if (!isAxiosError (error) || error.response?.status !== 404)
       throw error
-    const tag = await fetchWikiTag ({ wikiId: reference }, locale)
+    const tag = await fetchTagByName (reference, locale)
     return tag == null ? null : fetchWikiPageByTitle (tag.name, params, locale)
   }
 }
@@ -86,7 +128,9 @@ export const fetchWikiTag = async (
     return fetchTagByName (reference.name, locale)
   try
   {
-    return await apiGet (`/wiki/${encodeURIComponent (reference.wikiId)}/tag`, { locale })
+    const page = await fetchWikiPage (reference.wikiId, { }, locale)
+    return (page.resourceType === 'tag_description' && page.tagId != null)
+	? fetchTag (String (page.tagId), locale) : null
   }
   catch (error)
   {

frontend/src/locales/ain-Kana/navigation.json

@@ -14,6 +14,8 @@
   "materials": "チカㇻペ",
   "suppressions": "アエアイカㇷ゚テㇷ゚",
   "wiki": "Wiki",
+  "tagDescriptions": "$t(counts:resources.tag_descriptions)",
+  "tagGroups": "$t(counts:resources.tag_groups)",
   "create": "アシㇼ",
   "edit": "イヌイェㇷ゚",
   "entertainment": "シノッ",

frontend/src/locales/ja/navigation.json

@@ -13,6 +13,8 @@
   "materials": "素材",
   "suppressions": "抑止",
   "wiki": "Wiki",
+  "tagDescriptions": "$t(counts:resources.tag_descriptions)",
+  "tagGroups": "$t(counts:resources.tag_groups)",
   "create": "新規",
   "edit": "編輯",
   "entertainment": "おたのしみ",

frontend/src/pages/materials/MaterialDetailPage.tsx

@@ -135,7 +135,7 @@ const MaterialDetailPage: FC = () => {
 
 	      <TabGroup>
 		{material.tag && (
-		    <Tab name={label ('navigation:wiki')}>
+		    <Tab name={label ('navigation:tagDescriptions')}>
 		      <WikiBody
 			  title={material.tag.name}
 			  language={localeLanguage (locale)}

frontend/src/pages/posts/PostListPage.tsx

@@ -176,7 +176,7 @@ const PostListPage: FC = () => {
 	      {loading && label ('common:loading')}
 	    </Tab>
 	    {tags.length === 1 && (
-		<Tab name={label ('navigation:wiki')}>
+		<Tab name={label ('navigation:tagDescriptions')}>
 		  <WikiBody title={tags[0]} body={wikiPage?.body}
 		      language={wikiPage?.languageCode ?? (wikiPage?.resourceType === 'tag_description'
 			  ? localeLanguage (locale) : 'und')}/>

frontend/src/pages/wiki/WikiDetailPage.tsx

@@ -51,7 +51,8 @@ const WikiDetailPage: FC = () => {
       queryKey: helpKeys.titles ('ja'),
       queryFn: () => getHelpTitleIndex ('ja'),
       staleTime: Infinity })
-  const lookupTitle = title.trim ().normalize ('NFKC').toLowerCase ().replace (/^ヘルプ:/, '')
+  const lookupTitle = title.trim ().normalize ('NFKC').toLowerCase ()
+      .replace (/^(?:ヘルプ|手引):/, '')
   const identifiers = useMemo (() => (
       (titleIndex != null && Object.hasOwn (titleIndex, lookupTitle))
       ? titleIndex[lookupTitle] : []), [titleIndex, lookupTitle])

frontend/src/pages/wiki/WikiEditPage.tsx

@@ -11,8 +11,8 @@ import FormField from '@/components/common/FormField'
 import MainArea from '@/components/layout/MainArea'
 import { toast } from '@/components/ui/use-toast'
 import PageHead from '@/components/common/PageHead'
-import { apiGet, apiPut } from '@/lib/api'
-import { wikiKeys } from '@/lib/queryKeys'
+import { fetchWikiPage, saveTagDocument } from '@/lib/wiki'
+import { tagsKeys, wikiKeys } from '@/lib/queryKeys'
 import { canEditContent } from '@/lib/users'
 import { inputClass } from '@/lib/utils'
 import { useValidationErrors } from '@/lib/useValidationErrors'
@@ -33,7 +33,7 @@ const FIXED_WIKI_EDITOR_VIEW = { menu: true, md: true, html: true } as const
 
 type Props = { user: User | null }
 
-type WikiFormField = 'title' | 'body'
+type WikiFormField = 'title' | 'name' | 'body'
 
 
 const WikiEditPage: FC<Props> = ({ user }) => {
@@ -50,7 +50,7 @@ const WikiEditPage: FC<Props> = ({ user }) => {
   const source = `${locale}:${id}`
   const { data: wiki, isPending: loading } = useQuery ({
       queryKey: wikiKeys.show (id ?? '', { }, locale),
-      queryFn: () => apiGet<WikiPage> (`/wiki/${ encodeURIComponent (id ?? '') }`, { locale }),
+      queryFn: () => fetchWikiPage (id ?? '', { }, locale),
       enabled: editable })
   const [body, setBody] = useState (wiki?.body ?? '')
   const [loadedSource, setLoadedSource] = useState (wiki == null ? '' : source)
@@ -60,22 +60,19 @@ const WikiEditPage: FC<Props> = ({ user }) => {
       useValidationErrors<WikiFormField> ()
 
   const handleSubmit = async () => {
-    if (pending || !editable)
+    if (pending || !editable || wiki == null)
       return
     clearValidationErrors ()
 
-    const formData = new FormData ()
-    formData.append ('title', title)
-    formData.append ('body', body)
-
     try
     {
-      await apiPut (`/wiki/${ id }`, formData,
-		    { locale, headers: { 'Content-Type': 'multipart/form-data' } })
+      await saveTagDocument ({ title, body, page: wiki }, locale)
       qc.setQueryData (wikiKeys.show (title, { }, locale),
 		       (prev: WikiPage | undefined) =>
 			   prev == null ? prev : { ...prev, title, body })
-      qc.invalidateQueries ({ queryKey: wikiKeys.root })
+      await Promise.all ([
+	  qc.invalidateQueries ({ queryKey: wikiKeys.root }),
+	  qc.invalidateQueries ({ queryKey: tagsKeys.root })])
       toast ({ title: label ('shared:messages.postSuccess') })
       navigate (`/wiki/${ encodeURIComponent (title) }`)
     }
@@ -110,7 +107,7 @@ const WikiEditPage: FC<Props> = ({ user }) => {
 
 		{/* タイトル */}
 		{/* TODO: タグ補完 */}
-		<FormField label={label ('shared:labels.title')} messages={fieldErrors.title}>
+		<FormField label={label ('shared:labels.title')} messages={fieldErrors.title ?? fieldErrors.name}>
 		  {({ describedBy, invalid }) => (
 		      <input type="text"
 			     value={title}

frontend/src/pages/wiki/WikiNewPage.tsx

@@ -12,7 +12,7 @@ import FormField from '@/components/common/FormField'
 import MainArea from '@/components/layout/MainArea'
 import { toast } from '@/components/ui/use-toast'
 import PageHead from '@/components/common/PageHead'
-import { apiPost } from '@/lib/api'
+import { saveTagDocument } from '@/lib/wiki'
 import { tagsKeys, wikiKeys } from '@/lib/queryKeys'
 import { canEditContent } from '@/lib/users'
 import { inputClass } from '@/lib/utils'
@@ -21,7 +21,7 @@ import Forbidden from '@/pages/Forbidden'
 
 import type { FC } from 'react'
 
-import type { User, WikiPage } from '@/types'
+import type { User } from '@/types'
 
 const mdParser = new MarkdownIt
 const FIXED_WIKI_EDITOR_VIEW = { menu: true, md: true, html: true } as const
@@ -32,7 +32,7 @@ const FIXED_WIKI_EDITOR_VIEW = { menu: true, md: true, html: true } as const
 
 type Props = { user: User | null }
 
-type WikiFormField = 'title' | 'body'
+type WikiFormField = 'title' | 'name' | 'body'
 
 
 const WikiNewPage: FC<Props> = ({ user }) => {
@@ -55,14 +55,9 @@ const WikiNewPage: FC<Props> = ({ user }) => {
   const handleSubmit = async () => {
     clearValidationErrors ()
 
-    const formData = new FormData
-    formData.append ('title', title)
-    formData.append ('body', body)
-
     try
     {
-      const data = await apiPost<WikiPage> ('/wiki', formData,
-				  { locale, headers: { 'Content-Type': 'multipart/form-data' } })
+      const data = await saveTagDocument ({ title, body }, locale)
       await qc.cancelQueries ({ queryKey: wikiKeys.root })
       qc.setQueryData (wikiKeys.show (data.title, { }, locale), data)
       await Promise.all ([
@@ -91,7 +86,7 @@ const WikiNewPage: FC<Props> = ({ user }) => {
 
 	  {/* タイトル */}
 	  {/* TODO: タグ補完 */}
-	  <FormField label={label ('shared:labels.title')} messages={fieldErrors.title}>
+	  <FormField label={label ('shared:labels.title')} messages={fieldErrors.title ?? fieldErrors.name}>
 	    {({ describedBy, invalid }) => (
 		<input type="text"
 		       value={title}

frontend/src/pages/wiki/WikiSearchPage.tsx

@@ -8,7 +8,7 @@ import FormField from '@/components/common/FormField'
 import PageTitle from '@/components/common/PageTitle'
 import MainArea from '@/components/layout/MainArea'
 import PageHead from '@/components/common/PageHead'
-import { apiGet } from '@/lib/api'
+import { fetchWikiPages } from '@/lib/wiki'
 import { wikiKeys } from '@/lib/queryKeys'
 import { dateString, inputClass } from '@/lib/utils'
 
@@ -17,16 +17,20 @@ import type { FormEvent , FC } from 'react'
 import type { WikiPage } from '@/types'
 
 
-const WikiSearchPage: FC = () => {
+const WikiSearchPage: FC<{ resourceType?: WikiPage['resourceType'] }> = (
+    { resourceType = 'tag_description' },
+) => {
   const { message, label } = useUITranslation ('shared')
   const locale = useLocale ()
+  const heading =
+      resourceType === 'tag_group'
+      ? 'navigation:tagGroups' : 'navigation:tagDescriptions'
   const [title, setTitle] = useState ('')
   const [text, setText] = useState ('')
   const [submittedTitle, setSubmittedTitle] = useState ('')
   const { data: results = [], refetch } = useQuery ({
-      queryKey: wikiKeys.index ({ title: submittedTitle }, locale),
-      queryFn: () => apiGet<WikiPage[]> ('/wiki', {
-	  locale, params: { title: submittedTitle } }) })
+      queryKey: wikiKeys.index ({ title: submittedTitle, resourceType }, locale),
+      queryFn: () => fetchWikiPages ({ title: submittedTitle, resourceType }, locale) })
 
   const handleSearch = (ev: FormEvent) => {
     ev.preventDefault ()
@@ -42,10 +46,10 @@ const WikiSearchPage: FC = () => {
 
   return (
       <MainArea>
-	<PageHead title={message ('navigation:wiki')}/>
+	<PageHead title={message (heading)}/>
 
 	<div className="max-w-xl">
-	  <PageTitle>{label ('navigation:wiki')}</PageTitle>
+	  <PageTitle>{label (heading)}</PageTitle>
 	  <form onSubmit={handleSearch} className="space-y-2">
 	    {/* タイトル */}
 	    <FormField label={label ('labels.title')}>