#428

Reviewed-on: #432
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/app/controllers/application_controller.rb

@@ -1,10 +1,16 @@
 class ApplicationController < ActionController::API
+  class UnsupportedLocale < StandardError
+    ;
+  end
+
   rescue_from ActiveRecord::RecordInvalid, with: :render_record_invalid
   rescue_from ActiveRecord::RecordNotUnique, with: :render_record_not_unique
+  rescue_from(UnsupportedLocale) { head :not_found }
 
   before_action :reject_banned_ip_address!
   before_action :authenticate_user
   before_action :reject_banned_user!
+  before_action :validate_explicit_locale!
 
   def current_user = @current_user
 
@@ -93,5 +99,21 @@ class ApplicationController < ActionController::API
     value
   end
 
-  def resolve_locale! = Locale.find_by(code: params[:locale]) || Locale.nipponese
+  def resolve_locale!
+    return @resolved_locale if defined?(@resolved_locale)
+
+    code = params.fetch(:locale, 'ja')
+    unless code.is_a?(String) && Locale.codes.value?(code)
+      raise UnsupportedLocale
+    end
+
+    locale = Locale.find_by(code:)
+    raise UnsupportedLocale unless locale && locale.deprecated_at.nil?
+
+    @resolved_locale = locale
+  end
+
+  def validate_explicit_locale!
+    resolve_locale! if params.key?(:locale)
+  end
 end

backend/app/controllers/locales_controller.rb

@@ -0,0 +1,10 @@
+class LocalesController < ApplicationController
+  def index
+    locales = Locale.where(deprecated_at: nil).order(:created_at).map do |locale|
+      { code: locale.code_before_type_cast, name: locale.name }
+    end
+
+    response.headers['Cache-Control'] = 'no-store'
+    render json: { locales: }
+  end
+end

backend/app/controllers/materials_controller.rb

@@ -70,7 +70,10 @@ class MaterialsController < ApplicationController
         .find_by(id: params[:id])
     return head :not_found unless material
 
-    wiki_page_body = material.tag&.tag_name('ja')&.wiki_page&.current_revision&.body
+    wiki_page_body =
+        TagDescription
+        .find_by(tag_id: material.tag_id, language_code: locale.language_code)
+        &.body
 
     render json: MaterialRepr.base(material, host: request.base_url,
                                    language_code: locale.language_code).merge(wiki_page_body:)

backend/app/controllers/nico_tags_controller.rb

@@ -26,7 +26,7 @@ class NicoTagsController < ApplicationController
         ExternalTag
         .joins("LEFT JOIN (#{ post_tag_max_sql }) post_tag_max " \
                'ON post_tag_max.external_tag_id = external_tags.id')
-        .includes(linked_tags: { tag_names: :wiki_page })
+        .includes(linked_tags: [:tag_names, :tag_descriptions])
     if name
       q = q.where(('external_tags.name LIKE ? ' +
                    "OR CONCAT(external_tags.platform, ':', external_tags.name) LIKE ?"),

backend/app/controllers/post_versions_controller.rb

@@ -1,5 +1,6 @@
 class PostVersionsController < ApplicationController
   def index
+    locale = resolve_locale!
     post_id = params[:post].presence
     tag_id = params[:tag].presence&.to_i
     external_tag_id = params[:external_tag].presence&.to_i
@@ -45,12 +46,12 @@ class PostVersionsController < ApplicationController
                 .limit(limit)
                 .offset(offset)
 
-    render json: { versions: serialise_versions(versions), count: }
+    render json: { versions: serialise_versions(versions, locale.language_code), count: }
   end
 
   private
 
-  def serialise_versions rows
+  def serialise_versions rows, language_code
     rows = rows.to_a
     user_ids = rows.map(&:created_by_user_id).compact.uniq
     users_by_id = User.where(id: user_ids).pluck(:id, :name).to_h
@@ -58,12 +59,16 @@ class PostVersionsController < ApplicationController
       [normalise_json(row.tags_json),
        normalise_json(row.attributes['prev_tags_json']) || []]
     }
+    tag_ids = snapshots.flatten.filter_map { _1['tag_id'] }.uniq
+    tag_names = TagName.where(tag_id: tag_ids, language_code:, primary_flg: true)
+                       .pluck(:tag_id, :name).to_h
     external_tag_names = external_tag_names_for(snapshots)
 
     rows.map do |row|
-      cur_tags = snapshot_tag_literals(normalise_json(row.tags_json), external_tag_names)
+      cur_tags = snapshot_tag_literals(
+          normalise_json(row.tags_json), tag_names, external_tag_names)
       prev_tags = snapshot_tag_literals(
-          normalise_json(row.attributes['prev_tags_json']) || [], external_tag_names)
+          normalise_json(row.attributes['prev_tags_json']) || [], tag_names, external_tag_names)
 
       { post_id: row.post_id,
         version_no: row.version_no,
@@ -106,17 +111,23 @@ class PostVersionsController < ApplicationController
     names
   end
 
-  def snapshot_tag_literals snapshots, external_tag_names
+  def snapshot_tag_literals snapshots, tag_names, external_tag_names
     snapshots
         .filter_map { |snapshot|
           if snapshot.key?('tag_id')
+            sections = snapshot.fetch('sections', []).map { |section|
+              [section.fetch('begin_ms'), section['end_ms']]
+            }.sort_by { |begin_ms, end_ms| [begin_ms, end_ms || Float::INFINITY] }
+            name = tag_names[snapshot['tag_id']] || snapshot.fetch('name')
             [tag_category_order(snapshot['category']),
-             Post.tag_snapshot_literal(snapshot)]
+             { identity: [:tag, snapshot['tag_id'], sections],
+               name: Post.tag_snapshot_literal(snapshot.merge('name' => name)) }]
           elsif external_tag_names[snapshot['external_tag_id']]
-            [6, external_tag_names[snapshot['external_tag_id']]]
+            [6, { identity: [:external_tag, snapshot['external_tag_id']],
+                  name: external_tag_names[snapshot['external_tag_id']] }]
           end
         }
-        .sort_by { |order, name| [order, name.downcase] }
+        .sort_by { |order, tag| [order, tag[:name].downcase] }
         .map(&:second)
   end
 
@@ -125,17 +136,20 @@ class PostVersionsController < ApplicationController
   end
 
   def build_version_tags cur_tags, prev_tags
-    (cur_tags | prev_tags).map do |name|
+    current = cur_tags.to_h { [_1[:identity], _1[:name]] }
+    previous = prev_tags.to_h { [_1[:identity], _1[:name]] }
+
+    (current.keys | previous.keys).map do |identity|
       type =
-          if cur_tags.include?(name) && prev_tags.include?(name)
+          if current.key?(identity) && previous.key?(identity)
             'context'
-          elsif cur_tags.include?(name)
+          elsif current.key?(identity)
             'added'
           else
             'removed'
           end
 
-      { name:, type: }
+      { name: current[identity] || previous[identity], type: }
     end
   end
 end

backend/app/controllers/posts_controller.rb

@@ -53,7 +53,7 @@ class PostsController < ApplicationController
         .reselect('posts.*', Arel.sql("#{ updated_at_all_sql } AS updated_at_all"))
         .preload(:external_tags, :uploaded_user, :parents, :children,
                  post_tags: [:sections, { tag: [:deerjikists, :materials,
-                                                { tag_names: :wiki_page }] }])
+                                                :tag_names, :tag_descriptions] }])
         .with_attached_thumbnail
 
     q = q.where('posts.url LIKE ?', "%#{ url }%") if url
@@ -111,7 +111,7 @@ class PostsController < ApplicationController
         filtered_posts(locale)
         .preload(:uploaded_user, :parents, :children,
                  post_tags: [:sections, { tag: [:deerjikists, :materials,
-                                                { tag_names: :wiki_page }] }])
+                                                :tag_names, :tag_descriptions] }])
         .with_attached_thumbnail
         .order('RAND()')
         .first
@@ -198,7 +198,7 @@ class PostsController < ApplicationController
         Post
         .includes(:uploaded_user, :parents, :children,
                   post_tags: [:sections, { tag: [:deerjikists, :materials,
-                                                 { tag_names: :wiki_page }] }])
+                                                 :tag_names, :tag_descriptions] }])
         .with_attached_thumbnail
         .find_by(id: params[:id])
     return head :not_found unless post

backend/app/controllers/tag_descriptions_controller.rb

@@ -1,14 +1,18 @@
 class TagDescriptionsController < ApplicationController
   def show
-    description = TagDescription.find_by(tag_id: params[:id], language_code: 'ja')
+    locale = resolve_locale!
+    description = TagDescription.find_by(tag_id: params[:id], language_code: locale.language_code)
     return head :not_found unless description
 
     render json: representation(description)
   end
 
   def show_by_title
-    tag_name = TagName.find_by(language_code: 'ja', name: params[:name].to_s.strip)
-    description = tag_name&.tag && TagDescription.find_by(tag: tag_name.tag, language_code: 'ja')
+    locale = resolve_locale!
+    tag_name = TagName.find_by(
+        language_code: locale.language_code, name: params[:name].to_s.strip)
+    description = tag_name&.tag && TagDescription.find_by(
+        tag: tag_name.tag, language_code: locale.language_code)
     return head :not_found unless description
 
     render json: representation(description)
@@ -21,18 +25,19 @@ class TagDescriptionsController < ApplicationController
     body = params[:body].to_s
     return render_unprocessable_entity('本文は必須です．', field: :body) if body.blank?
 
+    locale = resolve_locale!
     tag = Tag.find_by(id: params[:id])
     return head :not_found unless tag
 
-    description = TagDescription.find_by(tag:, language_code: 'ja')
+    description = TagDescription.find_by(tag:, language_code: locale.language_code)
 
     if description
-      TagDescriptionOperation.update!(tag:, body:, updated_by_user: current_user)
+      TagDescriptionOperation.update!(locale, tag:, body:, updated_by_user: current_user)
       description.reload
       render json: representation(description)
     else
-      TagDescriptionOperation.create!(tag:, body:, created_by_user: current_user)
-      description = TagDescription.find_by!(tag:, language_code: 'ja')
+      TagDescriptionOperation.create!(locale, tag:, body:, created_by_user: current_user)
+      description = TagDescription.find_by!(tag:, language_code: locale.language_code)
       render json: representation(description), status: :created
     end
   rescue ActiveRecord::RecordInvalid => e

backend/app/controllers/tag_groups_controller.rb

@@ -1,33 +1,37 @@
 class TagGroupsController < ApplicationController
   def index
+    locale = resolve_locale!
     groups = TagGroup.includes(:created_by_user, :updated_by_user).order(:id)
-    render json: TagGroupRepr.many(groups.to_a)
+    render json: TagGroupRepr.many(locale, groups.to_a)
   end
 
   def show
+    locale = resolve_locale!
     group = TagGroup.includes(:created_by_user, :updated_by_user).find_by(id: params[:id])
     return head :not_found unless group
 
-    render json: TagGroupRepr.one(group)
+    render json: TagGroupRepr.one(locale, group)
   end
 
   def create
     return head :unauthorized unless current_user
     return head :forbidden unless current_user.gte_member?
 
-    group = TagGroupOperation.create!(**write_attributes, actor: current_user)
-    render json: TagGroupRepr.one(group), status: :created
+    locale = resolve_locale!
+    group = TagGroupOperation.create!(locale, **write_attributes, actor: current_user)
+    render json: TagGroupRepr.one(locale, group), status: :created
   end
 
   def update
     return head :unauthorized unless current_user
     return head :forbidden unless current_user.gte_member?
 
+    locale = resolve_locale!
     group = TagGroup.find_by(id: params[:id])
     return head :not_found unless group
 
-    TagGroupOperation.update!(group:, **write_attributes, actor: current_user)
-    render json: TagGroupRepr.one(group.reload)
+    TagGroupOperation.update!(locale, group:, **write_attributes, actor: current_user)
+    render json: TagGroupRepr.one(locale, group.reload)
   end
 
   private

backend/app/controllers/tag_versions_controller.rb

@@ -51,7 +51,7 @@ class TagVersionsController < ApplicationController
 
       tags_by_id =
           Tag
-          .includes(:tag_names, :materials, tag_names: :wiki_page)
+          .includes(:tag_names, :materials, :tag_descriptions, parents: :tag_descriptions)
           .where(id: all_parent_tag_ids)
           .index_by(&:id)
 

backend/app/controllers/tags_controller.rb

@@ -175,7 +175,7 @@ class TagsController < ApplicationController
     tags_by_id =
         Tag
         .joins(:tag_names)
-        .includes(:tag_names, :materials, tag_names: :wiki_page)
+        .includes(:tag_names, :materials, :tag_descriptions, parents: :tag_descriptions)
         .where(tag_names: { language_code: locale.language_code, primary_flg: true },
                id: tag_ids)
         .index_by(&:id)
@@ -238,7 +238,7 @@ class TagsController < ApplicationController
     base =
         Tag
         .joins(:tag_names)
-        .includes(:tag_names, :materials, tag_names: :wiki_page)
+        .includes(:tag_names, :materials, :tag_descriptions, parents: :tag_descriptions)
         .where(tag_names: { language_code: locale.language_code, primary_flg: true },
                deprecated_at: nil)
     base = base.where('tags.post_count > 0') if present_only
@@ -282,7 +282,7 @@ class TagsController < ApplicationController
     tag =
         Tag
         .joins(:tag_names)
-        .includes(:tag_names, :materials, tag_names: :wiki_page)
+        .includes(:tag_names, :materials, :tag_descriptions, parents: :tag_descriptions)
         .find_by(id: params[:id],
                  tag_names: { language_code: locale.language_code, primary_flg: true })
     return render json: TagRepr.base(tag, language_code: locale.language_code) if tag
@@ -302,7 +302,7 @@ class TagsController < ApplicationController
     tag =
         Tag
         .joins(:tag_names)
-        .includes(:tag_names, :materials, tag_names: :wiki_page)
+        .includes(:tag_names, :materials, :tag_descriptions, parents: :tag_descriptions)
         .find_by(tag_names: { name:, language_code: locale.language_code, primary_flg: true })
     return render json: TagRepr.base(tag, language_code: locale.language_code) if tag
 
@@ -320,7 +320,7 @@ class TagsController < ApplicationController
 
     tag = 
         Tag.joins(:tag_names)
-        .includes(:tag_names, tag_names: :wiki_page)
+        .includes(:tag_names, :tag_descriptions, parents: :tag_descriptions)
         .find_by(id: params[:id],
                  tag_names: { language_code: locale.language_code, primary_flg: true })
     return head :not_found unless tag
@@ -340,7 +340,7 @@ class TagsController < ApplicationController
     tag =
         Tag
         .joins(:tag_names)
-        .includes(:tag_names, tag_names: :wiki_page)
+        .includes(:tag_names, :tag_descriptions, parents: :tag_descriptions)
         .find_by(tag_names: { name:, language_code: locale.language_code, primary_flg: true })
     return head :not_found unless tag
 
@@ -359,7 +359,7 @@ class TagsController < ApplicationController
     tag =
         Tag
         .joins(:tag_names)
-        .includes(:tag_names, tag_names: :wiki_page)
+        .includes(:tag_names, :tag_descriptions, parents: :tag_descriptions)
         .find_by(id: params[:id],
                  tag_names: { language_code: locale.language_code, primary_flg: true })
     return head :not_found unless tag
@@ -424,7 +424,7 @@ class TagsController < ApplicationController
     tag =
         Tag
         .joins(:tag_names)
-        .includes(:tag_names, :materials, tag_names: :wiki_page)
+        .includes(:tag_names, :materials, :tag_descriptions, parents: :tag_descriptions)
         .find_by(tag_names: { name:, language_code: locale.language_code, primary_flg: true })
     return head :not_found unless tag
 
@@ -770,31 +770,15 @@ class TagsController < ApplicationController
       TagVersioning.ensure_snapshot!(old_owner_tag, created_by_user: current_user)
     end
 
-    current_tag_name.wiki_page&.update!(tag_name_id: promoted_tag_name.id)
-    current_tag_name.association(:wiki_page).reset
-
-    current_tag_name.update!(canonical_id: promoted_tag_name.id,
-                             primary_flg: false, auto_generated: false)
-    promoted_tag_name.update!(tag:, canonical_id: nil, primary_flg: true, auto_generated: false)
-
-    TagName.where(tag:,
-                  language_code: current_tag_name.language_code,
-                  primary_flg: false)
-           .where.not(id: promoted_tag_name.id)
-           .find_each do |alias_tag_name|
-      alias_tag_name.update!(canonical_id: promoted_tag_name.id, primary_flg: false)
-    end
-
-    tag.update!(tag_name_id: promoted_tag_name.id)
-    current_tag_name.association(:wiki_page).reset
-    current_tag_name.association(:tag).reset
-    current_tag_name.reload.update!(canonical_id: promoted_tag_name.id, primary_flg: false)
+    current_tag_name&.update!(primary_flg: false, auto_generated: false)
+    promoted_tag_name.update!(tag:, primary_flg: true, auto_generated: false)
+    tag.association(:tag_names).reset
 
     return unless old_owner_tag && old_owner_tag != tag
 
     record_tag_version!(old_owner_tag.reload, event_type: :update,
                         created_by_user: current_user,
-                        language_code: current_tag_name.language_code)
+                        language_code: promoted_tag_name.language_code)
   end
 
   def update_aliases! locale, tag, alias_names
@@ -802,20 +786,15 @@ class TagsController < ApplicationController
 
     affected_tags = [tag]
 
-    primary_tag_name = TagName.find_by!(tag:,
-                                        language_code: locale.language_code,
-                                        primary_flg: true)
     current_aliases = tag.tag_names.where(language_code: locale.language_code,
                                           primary_flg: false).to_a
 
-    current_aliases.each do |alias_tag_name|
-      next if alias_names.include?(alias_tag_name.name)
-
-      affected_tags << alias_tag_name.tag
-    end
+    requested_aliases = TagName.where(
+        language_code: locale.language_code, name: alias_names)
+        .includes(:tag).index_by(&:name)
 
     alias_names.each do |alias_name|
-      alias_tag_name = TagName.find_by(language_code: locale.language_code, name: alias_name)
+      alias_tag_name = requested_aliases[alias_name]
       if alias_tag_name&.primary? && alias_tag_name.tag_id && alias_tag_name.tag_id != tag.id
         alias_tag_name.errors.add(:name, 'その名前は既に使はれてゐます．')
         raise ActiveRecord::RecordInvalid, alias_tag_name
@@ -823,7 +802,8 @@ class TagsController < ApplicationController
       affected_tags << alias_tag_name&.tag
     end
 
-    affected_tags.compact.uniq.each do |affected_tag|
+    affected_tags = affected_tags.compact.uniq(&:id)
+    affected_tags.each do |affected_tag|
       TagVersioning.ensure_snapshot!(affected_tag, created_by_user: current_user,
                                      language_code: locale.language_code)
     end
@@ -831,19 +811,21 @@ class TagsController < ApplicationController
     current_aliases.each do |alias_tag_name|
       next if alias_names.include?(alias_tag_name.name)
 
-      alias_tag_name.update!(canonical_id: nil, tag_id: nil)
+      alias_tag_name.destroy!
     end
 
     alias_names.each do |alias_name|
-      alias_tag_name = TagName.find_or_initialize_by(
+      alias_tag_name = requested_aliases[alias_name] || TagName.new(
           language_code: locale.language_code,
           name: alias_name)
       alias_tag_name.script_code = locale.script_code
-      alias_tag_name.update!(tag:, primary_flg: false, auto_generated: false,
-                             canonical_id: primary_tag_name.id)
+      alias_tag_name.update!(tag:, primary_flg: false, auto_generated: false)
     end
 
-    affected_tags.compact.uniq.each do |affected_tag|
+    affected_tags.each do |affected_tag|
+      # update_all records this Tag after its parent relationships are updated.
+      next if affected_tag.id == tag.id
+
       record_tag_version!(affected_tag, event_type: :update,
                           created_by_user: current_user,
                           language_code: locale.language_code)

backend/app/controllers/wiki_pages_controller.rb

@@ -1,104 +1,106 @@
 class WikiPagesController < ApplicationController
-  rescue_from Wiki::Commit::Conflict, with: :render_wiki_conflict
+  # 互換性のための Facade API
+
+  rescue_from TagDescriptionOperation::Conflict, with: :render_wiki_conflict
 
   def index
-    # 互換性のための化石リソース
+    locale = resolve_locale!
 
     title = params[:title].to_s.strip
     descriptions =
-        TagDescription.where(language_code: 'ja')
+        TagDescription
+        .where(language_code: locale.language_code)
         .includes(tag: :tag_names)
-    pages = unmigrated_wiki_pages.includes(tag_name: :tag)
 
-    tag_groups = TagGroup.all
+    descriptions = descriptions.order(updated_at: :desc, id: :asc)
+    tag_groups = TagGroup.order(updated_at: :desc, id: :asc)
     if title.present?
       pattern = "%#{ ApplicationRecord.sanitize_sql_like(title) }%"
       descriptions =
           descriptions.joins(tag: :tag_names)
-          .where(tag_names: { language_code: 'ja', primary_flg: true })
+          .where(tag_names: { language_code: locale.language_code, primary_flg: true })
           .where('tag_names.name LIKE ?', pattern).limit(20)
       tag_groups = tag_groups.where(
-          'CONCAT(?, name) LIKE ?', TagGroupRepr::PREFIX, pattern).limit(20)
-      pages = pages.where('tag_names.name LIKE ?', pattern).limit(20)
+          'CONCAT(?, name) LIKE ? OR CONCAT(?, name) LIKE ?',
+          TagGroupRepr::PREFIX, pattern, 'tag_group:', pattern).limit(20)
     end
 
-    json = descriptions.map { |description| WikiPageRepr.tag_description(description) }
+    json = descriptions.map { |description| WikiPageRepr.tag_description(locale, description) }
     json.concat(tag_groups.map { WikiPageRepr.tag_group(_1) })
-    json.concat(WikiPageRepr.base(pages))
+    json.sort_by! do |row|
+      [-row['updated_at'].to_f, row.fetch('resource_type'), row.fetch('id')]
+    end
     json = json.first(20) if title.present?
     render json:
   end
 
   def show
-    tag_description = TagDescription.find_by(id: params[:id])
+    locale = resolve_locale!
+    tag_description = TagDescription.find_by(id: params[:id], language_code: locale.language_code)
 
-    return render_wiki_page_by_tag_description tag_description if tag_description
+    return render_wiki_page_by_tag_description locale, tag_description if tag_description
 
     tag_group = TagGroup.find_by(id: params[:id])
-    return render_tag_group tag_group if tag_group
+    return render_tag_group locale, tag_group if tag_group
 
-    page = WikiPage.joins(:tag_name)
-                   .includes(tag_name: :tag)
-                   .find_by(id: params[:id])
-
-    render_wiki_page_or_404 page
+    head :not_found
   end
 
   def show_by_title
+    locale = resolve_locale!
     title = params[:title].to_s.strip
 
-    if title.start_with?(TagGroupRepr::PREFIX)
-      name = title.delete_prefix(TagGroupRepr::PREFIX)
+    if (name = TagGroupRepr.name_from_title(title))
       tag_group = TagGroup.find_by(name:)
-      return render_tag_group tag_group if tag_group
+      return render_tag_group locale, tag_group if tag_group
       return head :not_found
     end
 
-    tag_description = tag_description_by_title(title)
+    tag_description = tag_description_by_title(locale, title)
 
-    return render_wiki_page_by_tag_description tag_description if tag_description
+    return render_wiki_page_by_tag_description locale, tag_description if tag_description
 
-    page =
-        WikiPage
-        .joins(:tag_name)
-        .includes(tag_name: :tag)
-        .find_by(tag_name: { name: title })
-
-    render_wiki_page_or_404 page
+    head :not_found
   end
 
   def exists
-    return head :no_content if TagDescription.exists?(id: params[:id])
+    locale = resolve_locale!
+    if TagDescription.exists?(id: params[:id], language_code: locale.language_code)
+      return head :no_content
+    end
     return head :no_content if TagGroup.exists?(id: params[:id])
 
-    head WikiPage.exists?(id: params[:id]) ? :no_content : :not_found
+    head :not_found
   end
 
   def exists_by_title
+    locale = resolve_locale!
     title = params[:title].to_s.strip
-    if title.start_with?(TagGroupRepr::PREFIX)
-      exists = TagGroup.exists?(name: title.delete_prefix(TagGroupRepr::PREFIX))
+    if (name = TagGroupRepr.name_from_title(title))
+      exists = TagGroup.exists?(name:)
       return head exists ? :no_content : :not_found
     end
-    return head :no_content if tag_description_by_title(title)
 
-    exists = WikiPage.joins(:tag_name).exists?(tag_names: { name: title })
-    head exists ? :no_content : :not_found
+    return head :no_content if tag_description_by_title(locale, title)
+
+    head :not_found
   end
 
   def diff
     id = params[:id]
     return render_bad_request('id は必須です．') if id.blank?
 
+    locale = resolve_locale!
+
     from = params[:from].presence
     to = params[:to].presence
 
-    description = TagDescription.find_by(id:)
+    description = TagDescription.find_by(id:, language_code: locale.language_code)
     if description
       versions = description_versions(description)
       from_rev = from && versions.find(from)
       to_rev = to ? versions.find(to) : versions.find_by!(version_no: description.version_no)
-      resource = WikiPageRepr.tag_description(description)
+      resource = WikiPageRepr.tag_description(locale, description)
     else
       tag_group = TagGroup.find_by(id:)
       if tag_group
@@ -106,21 +108,13 @@ class WikiPagesController < ApplicationController
         to_rev = to ? group_version(tag_group, to) : current_group_version(tag_group)
         return head :not_found if (from && !from_rev) || !to_rev
 
-        from_body = from_rev && render_group_version(from_rev)
-        to_body = render_group_version(to_rev)
+        from_body = from_rev && render_group_version(locale, from_rev)
+        to_body = render_group_version(locale, to_rev)
         resource = { 'id' => tag_group.id,
                      'title' => "#{ TagGroupRepr::PREFIX }#{ tag_group.name }",
                      'deprecated_at' => nil }
       else
-        page = WikiPage.joins(:tag_name).includes(tag_name: :tag).find(id)
-        from_rev = from && page.wiki_revisions.find(from)
-        to_rev = to ? page.wiki_revisions.find(to) : page.current_revision
-        if ((from_rev && !from_rev.content?) || !to_rev&.content?)
-          return render_unprocessable_entity('差分を表示できない版です．')
-        end
-        from_body = from_rev&.body
-        to_body = to_rev.body
-        resource = WikiPageRepr.base(page)
+        return head :not_found
       end
     end
 
@@ -149,37 +143,31 @@ class WikiPagesController < ApplicationController
     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?
 
-    if title.start_with?(TagGroupRepr::PREFIX)
-      name = title.delete_prefix(TagGroupRepr::PREFIX)
-      parsed = TagGroupMarkdownParser.parse(body:, group: nil)
-      group = TagGroupOperation.create!(name:, **parsed, actor: current_user,
-                                         require_compatibility: true)
+    locale = resolve_locale!
+
+    if (name = TagGroupRepr.name_from_title(title))
+      parsed = TagGroupMarkdownParser.parse(locale, body:, group: nil)
+      group = TagGroupOperation.create!(
+          locale, name:, **parsed.except(:compatibility_body), actor: current_user,
+          require_compatibility: true)
       version = current_group_version(group)
-      return render_group_representation(TagGroupRepr.one(group), version,
-                                         body: parsed.fetch(:compatibility_body),
+      return render_group_representation(TagGroupRepr.one(locale, group), version,
                                          status: :created)
     end
 
-    page = if title.include?(':')
-      ApplicationRecord.transaction do
-        tag_name = TagName.find_or_create_by!(language_code: 'ja', name: title) do |name|
-          name.script_code = 'Jpan'
-          name.primary_flg = true
-          name.auto_generated = false
+    description =
+        if title.include?(':')
+          return render_unprocessable_entity field: :title
+        else
+          tag_name = TagName.find_by(language_code: locale.language_code, name: title)
+          return render_unprocessable_entity field: :title unless tag_name&.tag
+
+          TagDescriptionOperation.create!(
+              locale,
+              tag: tag_name.tag, body:, created_by_user: current_user, message:)
         end
 
-        Wiki::Commit.create_legacy_content!(
-            tag_name:, body:, created_by_user: current_user, message:)
-      end
-    else
-      tag_name = TagName.find_by(language_code: 'ja', name: title)
-      return render_unprocessable_entity field: :title unless tag_name&.tag
-
-      TagDescriptionOperation.create!(
-          tag: tag_name.tag, body:, created_by_user: current_user, message:)
-    end
-
-    render json: WikiPageRepr.base(page), status: :created
+    render json: WikiPageRepr.tag_description(locale, description), status: :created
   rescue ActiveRecord::RecordInvalid => e
     render_validation_error e.record
   rescue ActiveRecord::RecordNotUnique
@@ -198,55 +186,47 @@ class WikiPagesController < ApplicationController
     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?
 
+    locale = resolve_locale!
+
     group = TagGroup.find_by(id: params[:id])
-    if title.start_with?(TagGroupRepr::PREFIX)
+    if (name = TagGroupRepr.name_from_title(title))
       return head :not_found unless group
 
-      name = title.delete_prefix(TagGroupRepr::PREFIX)
-      parsed = TagGroupMarkdownParser.parse(body:, group:)
-      TagGroupOperation.update!(group:, name:, **parsed, actor: current_user,
-                                require_compatibility: true)
+      parsed = TagGroupMarkdownParser.parse(locale, body:, group:)
+      TagGroupOperation.update!(
+          locale, group:, name:, **parsed.except(:compatibility_body), actor: current_user,
+          require_compatibility: true)
       return head :ok
     end
 
-    page = WikiPage.find_by(id: params[:id])
-    if legacy_group_page?(page)
-      return render_unprocessable_entity field: :title
+    return render_unprocessable_entity field: :title if title.include?(':')
+    description = TagDescription.find_by(id: params[:id], language_code: locale.language_code)
+    unless description
+      return render_unprocessable_entity field: :title if group
+      return head :not_found
     end
-    if group && !legacy_update_identified?(page, title, group)
-      return render_unprocessable_entity field: :title
-    end
-    return head :not_found unless page
+
+    tag = description.tag
+    tag_name = tag.tag_name(locale.language_code)
+    return render_unprocessable_entity field: :title unless tag_name
+    return render_unprocessable_entity field: :title if tag_name.name.include?(':')
 
     base_revision_id = params[:base_revision_id].presence
 
     ApplicationRecord.transaction do
-      page.lock!
-
-      old_title = page.title
-
-      tag = page.tag_name.tag
-
-      if tag && title != old_title
+      tag.lock!
+      old_title = tag_name.name
+      if title != old_title
         TagVersioning.ensure_snapshot!(tag, created_by_user: current_user)
       end
 
-      page.tag_name.update!(name: title) if title != old_title
+      tag_name.update!(name: title) if title != old_title
 
       message = params[:message].presence
-      description = TagDescription.find_by(id: page.id)
-      description_page = description && (
-          tag&.id == description.tag_id ||
-          (tag.nil? && !old_title.include?(':')))
-      if description && !description_page
-        Wiki::Commit.legacy_content!(page:, body:, created_user: current_user,
-                                     message:, base_revision_id:)
-      else
-        Wiki::Commit.content!(page:, body:, created_user: current_user,
-                              message:, base_revision_id:)
-      end
+      TagDescriptionOperation.update!(locale, tag:, body:, updated_by_user: current_user,
+                                      message:, base_revision_id:)
 
-      if tag && title != old_title
+      if title != old_title
         tag.reload
         TagVersionRecorder.record!(tag:, event_type: :update, created_by_user: current_user)
       end
@@ -262,10 +242,12 @@ class WikiPagesController < ApplicationController
   end
 
   def changes
+    locale = resolve_locale!
+
     id = params[:id].presence
-    description = id && TagDescription.find_by(id:)
+    description = id && TagDescription.find_by(id:, language_code: locale.language_code)
     if description
-      return render json: description_changes(TagDescription.where(id: description.id))
+      return render json: description_changes(locale, TagDescription.where(id: description.id))
     end
 
     tag_group = id && TagGroup.find_by(id:)
@@ -273,26 +255,11 @@ class WikiPagesController < ApplicationController
       return render json: tag_group_changes(TagGroupVersion.where(tag_group_id: tag_group.id))
     end
 
-    pages = id ? WikiPage.where(id:) : unmigrated_wiki_pages
-    revisions = WikiRevision.joins(wiki_page: :tag_name)
-        .where(wiki_page_id: pages.select(:id))
-        .includes(:created_user, wiki_page: { tag_name: :tag })
-        .order(id: :desc).limit(200)
-    json = revisions.map { |rev|
-      { revision_id: rev.id,
-        pred: rev.base_revision_id,
-        succ: nil,
-        wiki_page: { id: rev.wiki_page_id,
-                     title: rev.wiki_page.title,
-                     deprecated_at: rev.wiki_page.deprecated_at },
-        user: rev.created_user && { id: rev.created_user.id, name: rev.created_user.name },
-        kind: rev.kind,
-        message: rev.message,
-        timestamp: rev.created_at }
-    }
+    json = []
     unless id
       json.concat(tag_group_changes(TagGroupVersion.all))
-      json.concat(description_changes(TagDescription.where(language_code: 'ja')))
+      json.concat(description_changes(locale,
+                                      TagDescription.where(language_code: locale.language_code)))
       json = json.each_with_index.sort_by do |row, index|
         [-row.fetch(:timestamp).to_f, index]
       end.map(&:first)
@@ -302,27 +269,7 @@ class WikiPagesController < ApplicationController
 
   private
 
-  def legacy_group_page? page
-    return false unless page
-    return true if page.title.start_with?(TagGroupRepr::PREFIX)
-
-    prefix = ApplicationRecord.sanitize_sql_like(TagGroupRepr::PREFIX)
-    page.wiki_versions.where('title LIKE ?', "#{ prefix }%").exists?
-  end
-
-  def legacy_update_identified? page, title, group
-    return false unless page
-    return true if page.title == title
-    return false if title == group.name
-
-    namespace = page.title.split(':', 2)
-    return true if namespace.size == 2 && title.start_with?("#{ namespace.first }:")
-
-    base = params[:base_revision_id].presence
-    base && page.wiki_revisions.exists?(id: base)
-  end
-
-  def render_tag_group group
+  def render_tag_group locale, group
     version = if params[:version].present?
       group_version(group, params[:version])
     else
@@ -330,16 +277,17 @@ class WikiPagesController < ApplicationController
     end
     return head :not_found unless version
 
-    representation = if params[:version].present?
-      TagGroupRepr.historical(version)
-    else
-      TagGroupRepr.one(group)
-    end
+    representation =
+        if params[:version].present?
+          TagGroupRepr.historical(locale, version)
+        else
+          TagGroupRepr.one(locale, group)
+        end
     render_group_representation(representation, version)
   end
 
-  def render_group_version version
-    representation = TagGroupRepr.historical(version)
+  def render_group_version locale, version
+    representation = TagGroupRepr.historical(locale, version)
     TagGroupMarkdownRenderer.render(representation)
   end
 
@@ -351,6 +299,7 @@ class WikiPagesController < ApplicationController
     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,
@@ -407,28 +356,7 @@ class WikiPagesController < ApplicationController
     end
   end
 
-  def render_wiki_page_or_404 page
-    return head :not_found unless page
-
-    rev = find_revision(page)
-    return head :not_found unless rev
-
-    if rev.redirect?
-      return (
-          redirect_to wiki_page_by_title_path(title: rev.redirect_page.title),
-                      status: :moved_permanently)
-    end
-
-    body = rev.body
-    revision_id = rev.id
-    pred = page.pred_revision_id(revision_id)
-    succ = page.succ_revision_id(revision_id)
-    updated_at = rev.created_at
-
-    render json: WikiPageRepr.base(page).merge(body:, revision_id:, pred:, succ:, updated_at:)
-  end
-
-  def render_wiki_page_by_tag_description description
+  def render_wiki_page_by_tag_description locale, description
     versions = description_versions(description)
     historical = params[:version].present?
     rev = historical ? versions.find_by(id: params[:version]) :
@@ -439,7 +367,7 @@ class WikiPagesController < ApplicationController
     succ = versions.find_by(version_no: rev.version_no + 1)&.id
     body = historical ? rev.body : description.body
     updated_at = historical ? rev.created_at : description.updated_at
-    render json: WikiPageRepr.tag_description(description).merge(
+    render json: WikiPageRepr.tag_description(locale, description).merge(
         body:, revision_id: rev.id, pred:, succ:, updated_at:)
   end
 
@@ -448,23 +376,14 @@ class WikiPagesController < ApplicationController
                                 language_code: description.language_code)
   end
 
-  def tag_description_by_title title
+  def tag_description_by_title locale, title
     TagDescription.joins(tag: :tag_names)
-        .find_by(language_code: 'ja', tag_names: { language_code: 'ja', name: title })
+        .find_by(language_code: locale.language_code,
+                 tag_names: { language_code: locale.language_code, name: title })
   end
 
-  def unmigrated_wiki_pages
-    descriptions = TagDescription.where(language_code: 'ja')
-
-    WikiPage
-        .joins(:tag_name)
-        .where.not('tag_names.name LIKE ?', "#{ TagGroupRepr::PREFIX }%")
-        .where('tag_names.tag_id IS NULL OR tag_names.tag_id NOT IN (?)',
-               descriptions.select(:tag_id))
-  end
-
-  def description_changes descriptions
-    versions = TagDescriptionVersion.where(language_code: 'ja',
+  def description_changes locale, descriptions
+    versions = TagDescriptionVersion.where(language_code: locale.language_code,
                                            tag_id: descriptions.select(:tag_id))
         .order(id: :desc).limit(200).to_a
     return [] if versions.empty?
@@ -473,7 +392,7 @@ class WikiPagesController < ApplicationController
         .includes(tag: :tag_names).index_by(&:tag_id)
     users = User.where(id: versions.map(&:created_by_user_id)).index_by(&:id)
     predecessors = TagDescriptionVersion.where(
-        language_code: 'ja', tag_id: by_tag.keys,
+        language_code: locale.language_code, tag_id: by_tag.keys,
         version_no: versions.map { |version| version.version_no - 1 })
         .pluck(:tag_id, :version_no, :id)
         .to_h { |tag_id, version_no, id| [[tag_id, version_no], id] }
@@ -483,7 +402,7 @@ class WikiPagesController < ApplicationController
       { revision_id: version.id,
         pred: predecessors[[version.tag_id, version.version_no - 1]],
         succ: nil,
-        wiki_page: { id: description.id, title: description.tag.name('ja'),
+        wiki_page: { id: description.id, title: description.tag.name(locale.language_code),
                      deprecated_at: description.tag.deprecated_at },
         user: user && { id: user.id, name: user.name },
         kind: 'content',
@@ -492,14 +411,6 @@ class WikiPagesController < ApplicationController
     end
   end
 
-  def find_revision page
-    if params[:version].present?
-      page.wiki_revisions.find_by(id: params[:version])
-    else
-      page.current_revision
-    end
-  end
-
   def render_wiki_conflict err
     render json: { error: 'conflict', message: err.message }, status: :conflict
   end

backend/app/models/external_tag.rb

@@ -1,4 +1,6 @@
 class ExternalTag < ApplicationRecord
+  before_create { SharedResourceIdAllocator.assign!(self) }
+
   enum :platform, nico: 'nico'
   validates :platform, presence: true, inclusion: { in: ExternalTag.platforms.keys }
 

backend/app/models/language.rb

@@ -1,5 +1,5 @@
 class Language < ApplicationRecord
   has_many :locales, foreign_key: :language_code, primary_key: :code
 
-  enum :code, ja: 'ja'
+  enum :code, ja: 'ja', ain: 'ain'
 end

backend/app/models/locale.rb

@@ -1,27 +1,18 @@
 class Locale < ApplicationRecord
-  after_create_commit :generate_tag_names!
+  after_save :generate_tag_names!, if: :needs_tag_names?
 
   belongs_to :language, foreign_key: :language_code, primary_key: :code
   belongs_to :script, foreign_key: :script_code, primary_key: :code
 
-  enum :code, ja: 'ja', en: 'en', fr: 'fr'
+  enum :code, ja: 'ja', ain_kana: 'ain-Kana'
 
   def self.nipponese = Locale.find('ja')
 
   private
 
-  def generate_tag_names!
-    ApplicationRecord.transaction do
-      tag_ids = TagName.where(language_code:, primary_flg: true).pluck(:tag_id)
-      Tag.where.not(id: tag_ids).find_each do
-        TagName.create!(tag_id: _1.id,
-                        language_code:,
-                        name: TagName.generate_name(self, _1, _1.tag_name('ja')),
-                        script_code:,
-                        primary_flg: true,
-                        auto_generated: true,
-                        canonical_id: nil)
-      end
-    end
+  def needs_tag_names?
+    deprecated_at.nil? && (saved_change_to_code? || saved_change_to_deprecated_at?)
   end
+
+  def generate_tag_names! = TagNameCompletion.for_locale!(self)
 end

backend/app/models/script.rb

@@ -1,5 +1,5 @@
 class Script < ApplicationRecord
   has_many :locales, foreign_key: :script_code, primary_key: :code
 
-  enum :code, Jpan: 'Jpan'
+  enum :code, jpan: 'Jpan', kana: 'Kana'
 end

backend/app/models/tag.rb

@@ -2,6 +2,8 @@ require 'set'
 
 
 class Tag < ApplicationRecord
+  before_create { SharedResourceIdAllocator.assign!(self) }
+
   class NicoTagNormalisationError < ArgumentError
     ;
   end
@@ -51,6 +53,7 @@ class Tag < ApplicationRecord
   has_many :tag_versions
 
   has_many :tag_names
+  has_many :tag_descriptions
 
   attribute :version_no, :integer, default: 1
 
@@ -88,7 +91,6 @@ class Tag < ApplicationRecord
     end
   end
   def name(language_code) = tag_name(language_code)&.name
-  def wiki_page = tag_name('ja')&.wiki_page
 
   def system?
     tag_name('ja')&.name.in?(SYSTEM_TAG_NAMES)
@@ -96,13 +98,19 @@ class Tag < ApplicationRecord
 
   def deprecated? = deprecated_at?
 
-  def has_wiki = wiki_page.present?
+  def has_description? language_code:
+    if tag_descriptions.loaded?
+      tag_descriptions.any? { _1.language_code == language_code }
+    else
+      tag_descriptions.exists?(language_code:)
+    end
+  end
 
   def material_id = materials.first&.id
 
   def has_deerjikists = deerjikists.loaded? ? deerjikists.any? : deerjikists.exists?
 
-  def snapshot_aliases(language_code)
+  def snapshot_aliases language_code
     tag_names.where(language_code:, primary_flg: false).order(:name).pluck(:name)
   end
 
@@ -251,23 +259,23 @@ class Tag < ApplicationRecord
       name = name.to_s.strip
 
       ApplicationRecord.transaction do
-        tn = TagName.find_or_create_by!(language_code:, name:) do
-          _1.script_code = locale.script_code
-          _1.primary_flg = true
-        end
+        tn = TagName.find_by(language_code:, name:)
+        next tn.tag if tn
 
-        tag = tn.tag
-        next tag if tag
-
-        tag = Tag.create!(tag_name_id: tn.id, category:)
-        tn.update!(tag:, primary_flg: true, canonical_id: nil, auto_generated: false)
-        generate_tag_names!(locale, tag, tn)
+        tag = Tag.create!(category:)
+        TagName.create!(tag:, language_code:, name:,
+                        script_code: locale.script_code, primary_flg: true,
+                        auto_generated: false)
+        TagNameCompletion.for_tag!(tag)
         tag.association(:tag_names).reset
 
         tag
       end
     rescue ActiveRecord::RecordNotUnique
-      retry
+      existing = TagName.find_by(language_code:, name:)
+      raise unless existing
+
+      existing.tag
     end
 
     def merge_tags! target_tag, source_tags, created_by_user: nil
@@ -294,20 +302,18 @@ class Tag < ApplicationRecord
             end
           end
 
-          source_tag_name = source_tag.tag_name('ja')
-
-          if source_tag_name.wiki_page.present?
-            raise ActiveRecord::RecordInvalid.new(source_tag_name)
+          if source_tag.tag_descriptions.exists?
+            source_tag.errors.add(:base, :invalid)
+            raise ActiveRecord::RecordInvalid, source_tag
           end
 
           TagVersioning.record!(source_tag, event_type: :discard, created_by_user:)
-          source_tag.tag_names.update_all(tag_id: target_tag.id, primary_flg: false,
-                                          updated_at: Time.current)
+          target_languages = target_tag.tag_names.where(primary_flg: true).pluck(:language_code)
+          source_tag.tag_names.where(language_code: target_languages)
+              .update_all(primary_flg: false, auto_generated: false, updated_at: Time.current)
+          source_tag.tag_names.update_all(tag_id: target_tag.id, updated_at: Time.current)
           source_tag.destroy!
 
-          source_tag_name.update_columns(canonical_id: target_tag.tag_name_id,
-                                         updated_at: Time.current)
-
           TagVersioning.record!(target_tag, event_type: :update, created_by_user:)
         end
 
@@ -349,29 +355,6 @@ class Tag < ApplicationRecord
       total_s * 1_000 + match[:ms].to_s.ljust(3, '0')[0, 3].to_i
     end
 
-    private
-
-    def generate_tag_names! locale, tag, base_tag_name
-      ApplicationRecord.transaction do
-        locales =
-            Locale
-            .where(deprecated_at: nil)
-            .where.not(language_code: locale.language_code)
-            .order(:language_code, :created_at, :script_code)
-            .uniq { _1.language_code }
-        locales.each do |locale|
-          language_code = locale.language_code
-          script_code = locale.script_code
-          TagName.create!(tag_id: tag.id,
-                          language_code:,
-                          name: TagName.generate_name(locale, tag, base_tag_name),
-                          script_code:,
-                          primary_flg: true,
-                          auto_generated: true,
-                          canonical_id: nil)
-        end
-      end
-    end
   end
 
   private

backend/app/models/tag_description.rb

@@ -1,3 +1,5 @@
 class TagDescription < ApplicationRecord
+  before_create { SharedResourceIdAllocator.assign!(self) }
+
   belongs_to :tag
 end

backend/app/models/tag_description_version.rb

@@ -1,3 +1,3 @@
 class TagDescriptionVersion < ApplicationRecord
-  ;
+  before_create { SharedResourceIdAllocator.assign!(self) }
 end

backend/app/models/tag_group.rb

@@ -1,4 +1,7 @@
 class TagGroup < ApplicationRecord
+  before_create { SharedResourceIdAllocator.assign!(self) }
+  before_destroy :delete_current_structure!
+
   belongs_to :created_by_user, class_name: 'User', optional: true
   belongs_to :updated_by_user, class_name: 'User', optional: true
 
@@ -9,8 +12,16 @@ class TagGroup < ApplicationRecord
   has_many :placements, -> { order(:position) },
            class_name: 'TagGroupPlacement', dependent: :delete_all
   has_many :versions, -> { order(:version_no) },
-           class_name: 'TagGroupVersion', dependent: :delete_all
+           class_name: 'TagGroupVersion'
 
   validates :name, presence: true, uniqueness: true, length: { maximum: 255 }
   validates :version_no, numericality: { only_integer: true, greater_than: 0 }
+
+  private
+
+  def delete_current_structure!
+    placements.reorder(position: :desc).each(&:delete)
+    tag_group_tags.delete_all
+    tag_group_groups.delete_all
+  end
 end

backend/app/models/tag_group_version.rb

@@ -1,6 +1,8 @@
 class TagGroupVersion < ApplicationRecord
   include VersionRecord
 
+  before_create { SharedResourceIdAllocator.assign!(self) }
+
   belongs_to :tag_group
 
   scope :ordered, -> { order(:version_no) }

backend/app/models/tag_name.rb

@@ -1,14 +1,12 @@
 class TagName < ApplicationRecord
   belongs_to :language, foreign_key: :language_code, primary_key: :code
-  belongs_to :tag, optional: true
-  has_one :wiki_page
+  belongs_to :tag
 
   validates :name, presence: true,
                    length: { maximum: 255 },
                    uniqueness: { scope: :language_code }
 
   validate :alias_name_must_not_have_prefix
-  validate :alias_must_not_have_wiki_page
   validate :name_must_be_sanitised
   validate :name_mustnt_start_with_nico
   validate :generated_name_must_be_reserved
@@ -21,22 +19,30 @@ class TagName < ApplicationRecord
 
     tns = TagName.where(language_code: locale.language_code, name: names).index_by(&:name)
 
+    primary_names = TagName.where(
+        language_code: locale.language_code, tag_id: tns.values.map(&:tag_id),
+        primary_flg: true).pluck(:tag_id, :name).to_h
+
     names.map { |name|
       tag_name = tns[name]
-      if !tag_name || tag_name.primary? || tag_name.tag_id.nil?
+      if !tag_name || tag_name.primary?
         name
       else
-        TagName.find_by(language_code: locale.language_code,
-                        tag_id: tag_name.tag_id,
-                        primary_flg: true)&.name || name
+        primary_names[tag_name.tag_id] || name
       end
     }.uniq
   end
 
   def self.generate_name locale, tag, base_tag_name
-    # TODO: 言語ごとの自動命名ロジック完成したら書く．
+    fallback = "Tag_##{ tag.id }"
+    return fallback unless locale.language_code == 'ain' && base_tag_name&.language_code == 'ja'
 
-    "Tag_##{ tag.id }"
+    name = TagNameTranscription.ainu(base_tag_name.name)
+    candidate = new(tag:, name:, language_code: 'ain', script_code: 'Kana',
+                    primary_flg: true, auto_generated: true)
+    candidate.valid? ? name : fallback
+  rescue TagNameTranscription::Unconvertible
+    fallback
   end
 
   private
@@ -53,13 +59,9 @@ class TagName < ApplicationRecord
     end
   end
 
-  def alias_must_not_have_wiki_page
-    if !(primary?) && wiki_page
-      errors.add :primary_flg, 'Wiki 参照がある名前はエーリアスになれません．'
-    end
-  end
-
   def name_must_be_sanitised
+    return if auto_generated && name == "Tag_##{ tag_id }"
+
     if name? && name != TagNameSanitisationRule.sanitise(name)
       errors.add :name, '名前に使用できない文字が含まれてゐます．'
     end

backend/app/models/tag_name_sanitisation_rule.rb

@@ -16,37 +16,36 @@ class TagNameSanitisationRule < ApplicationRecord
 
     def apply!
       Language.find_each do |language|
-        TagName.where(language:).find_each do |tn|
-          name = sanitise(tn.name)
-          next if name == tn.name
-
+        TagName.where(language:).find_each do |candidate|
           TagName.transaction do
+            tn = TagName.find_by(id: candidate.id)
+            next unless tn
+
+            name = sanitise(tn.name)
+            next if name == tn.name
+
             existing_tn = TagName.find_by(language:, name:)
-            if existing_tn
-              unless existing_tn.primary_flg
-                existing_tn = TagName.find_by!(language:,
-                                               tag_id: existing_tn.tag_id,
-                                               primary_flg: true)
+            source_tag = tn.tag
+            target_tag = existing_tn ? existing_tn.tag : source_tag
+            [source_tag, target_tag].uniq(&:id).sort_by(&:id).each(&:lock!)
+            TagVersioning.ensure_snapshot!(source_tag, created_by_user: nil)
+
+            if existing_tn && target_tag != source_tag
+              Tag.merge_tags!(target_tag, source_tag)
+              tn.reload.destroy!
+            elsif existing_tn
+              if tn.primary?
+                existing_tn.destroy!
+                tn.update_columns(name:, updated_at: Time.current)
+              else
+                tn.destroy!
               end
-              next if existing_tn.id == tn.id
-
-              existing_tag = existing_tn.tag
-              source_tag = tn.tag
-
-              if existing_tag
-                Tag.merge_tags!(existing_tag, source_tag) if tn.tag
-              elsif source_tag
-                tn.update_columns(tag_id: nil, updated_at: Time.current)
-                source_tag.update_columns(tag_name_id: existing_tn.id, updated_at: Time.current)
-                existing_tn.update_columns(tag_id: source_tag.id, updated_at: Time.current)
-              end
-              tn.destroy!
-
-              next
+            else
+              # TagName 側の自動サニタイズを回避
+              tn.update_columns(name:, updated_at: Time.current)
             end
 
-            # TagName 側の自動サニタイズを回避
-            tn.update_columns(name:, updated_at: Time.current)
+            TagVersioning.record!(target_tag, event_type: :update, created_by_user: nil)
           end
         end
       end

backend/app/models/user.rb

@@ -13,10 +13,10 @@ class User < ApplicationRecord
   has_many :ip_addresses, through: :user_ips
   has_many :user_post_views, dependent: :destroy
   has_many :viewed_posts, through: :user_post_views, source: :post
-  has_many :created_wiki_pages,
-           class_name: 'WikiPage', foreign_key: :created_user_id, dependent: :nullify
-  has_many :updated_wiki_pages,
-           class_name: 'WikiPage', foreign_key: :updated_user_id, dependent: :nullify
+  has_many :created_tag_descriptions, class_name: 'TagDescription',
+           foreign_key: :created_by_user_id, dependent: :nullify
+  has_many :updated_tag_descriptions, class_name: 'TagDescription',
+           foreign_key: :updated_by_user_id, dependent: :nullify
 
   def viewed?(post) = user_post_views.exists?(post_id: post.id)
 

backend/app/models/wiki_line.rb

@@ -1,15 +0,0 @@
-class WikiLine < ApplicationRecord
-  has_many :wiki_revision_lines, dependent: :restrict_with_exception
-
-  validates :sha256, presence: true, uniqueness: true, length: { is: 64 }
-  validates :body, presence: true
-
-  def self.upsert_by_body! body
-    sha = Digest::SHA256.hexdigest(body)
-    now = Time.current
-
-    upsert(sha256: sha, body:, created_at: now, updated_at: now)
-
-    find_by!(sha256: sha)
-  end
-end

backend/app/models/wiki_page.rb

@@ -1,58 +0,0 @@
-require 'set'
-
-
-class WikiPage < ApplicationRecord
-  include MyDiscard
-
-  has_many :wiki_revisions, dependent: :destroy
-  belongs_to :created_user, class_name: 'User'
-  belongs_to :updated_user, class_name: 'User'
-
-  has_many :redirected_from_revisions,
-           class_name: 'WikiRevision',
-           foreign_key: :redirect_page_id,
-           dependent: :nullify
-
-  has_many :wiki_versions
-
-  attribute :version_no, :integer, default: 1
-
-  belongs_to :tag_name
-  validates :tag_name, presence: true
-  validates :body, presence: true
-
-  def title = tag_name.name
-  def deprecated_at = tag_name.tag&.deprecated_at
-
-  def title= val
-    (self.tag_name ||= build_tag_name).name = val
-  end
-
-  def current_revision = wiki_revisions.order(id: :desc).first
-
-  def resolve_redirect limit: 10
-    page = self
-    visited = Set.new
-
-    limit.times do
-      return page if visited.include?(page.id)
-
-      visited.add(page.id)
-
-      rev = page.current_revision
-      return page if !(rev&.redirect?) || !(rev.redirect_page)
-
-      page = rev.redirect_page
-    end
-
-    page
-  end
-
-  def pred_revision_id revision_id
-    wiki_revisions.where('id < ?', revision_id).order(id: :desc).limit(1).pick(:id)
-  end
-
-  def succ_revision_id revision_id
-    wiki_revisions.where('id > ?', revision_id).order(id: :asc).limit(1).pick(:id)
-  end
-end

backend/app/models/wiki_revision.rb

@@ -1,55 +0,0 @@
-class WikiRevision < ApplicationRecord
-  belongs_to :wiki_page
-  belongs_to :base_revision, class_name: 'WikiRevision', optional: true
-  belongs_to :created_user, class_name: 'User'
-  belongs_to :redirect_page, class_name: 'WikiPage', optional: true
-
-  has_many :wiki_revision_lines, dependent: :delete_all
-  has_many :wiki_lines, through: :wiki_revision_lines
-
-  enum :kind, content: 0, redirect: 1
-
-  validates :kind, presence: true
-  validates :lines_count, numericality: { only_integer: true, greater_than_or_equal_to: 0 }
-  validates :tree_sha256, length: { is: 64 }, allow_nil: true
-
-  validate :kind_consistency
-
-  def body
-    return unless content?
-
-    wiki_revision_lines
-        .includes(:wiki_line)
-        .order(:position)
-        .map { |rev| rev.wiki_line.body }
-        .join("\n")
-  end
-
-  private
-
-  def kind_consistency
-    if content?
-      if tree_sha256.blank?
-        errors.add(:tree_sha256, '種類がページの場合は必須です．') 
-      end
-
-      if redirect_page_id.present?
-        errors.add(:redirect_page_id, '種類がページの場合は空である必要があります．')
-      end
-    end
-
-    if redirect?
-      if redirect_page_id.blank?
-        errors.add(:redirect_page_id, '種類がリダイレクトの場合は必須です．')
-      end
-
-      if tree_sha256.present?
-        errors.add(:tree_sha256, '種類がリダイレクトの場合は空である必要があります．')
-      end
-
-      if lines_count.to_i > 0
-        errors.add(:lines_count, '種類がリダイレクトの場合は 0 である必要があります．')
-      end
-    end
-  end
-end

backend/app/models/wiki_revision_line.rb

@@ -1,8 +0,0 @@
-class WikiRevisionLine < ApplicationRecord
-  belongs_to :wiki_revision
-  belongs_to :wiki_line
-
-  validates :position, presence: true,
-                       numericality: { only_integer: true, greater_than_or_equal_to: 0 }
-  validates :position, uniqueness: { scope: :wiki_revision_id }
-end

backend/app/models/wiki_version.rb

@@ -1,8 +0,0 @@
-class WikiVersion < ApplicationRecord
-  include VersionRecord
-
-  belongs_to :wiki_page
-
-  validates :title, presence: true
-  validates :body, presence: true
-end

backend/app/representations/tag_group_repr.rb

@@ -3,7 +3,12 @@ module TagGroupRepr
 
   module_function
 
-  def many groups
+  def name_from_title title
+    prefix = [PREFIX, 'tag_group:'].find { title.downcase.start_with?(_1) }
+    title[prefix.length..] if prefix
+  end
+
+  def many locale, groups
     ids = groups.map(&:id)
     return [] if ids.empty?
 
@@ -14,14 +19,20 @@ module TagGroupRepr
     placements = TagGroupPlacement.where(tag_group_id: ids).order(:position)
         .group_by(&:tag_group_id)
 
-    target_ids = tag_members.values.flatten.map(&:tag_id) +
-        group_members.values.flatten.map(&:child_tag_group_id) +
+    target_ids =
+        tag_members.values.flatten.map(&:tag_id) +
         placements.values.flatten.filter_map(&:tag_id)
-    child_ids = group_members.values.flatten.map(&:child_tag_group_id) +
+    child_ids =
+        group_members.values.flatten.map(&:child_tag_group_id) +
         placements.values.flatten.filter_map(&:child_tag_group_id)
     tags = Tag.select(:id, :category).where(id: target_ids.uniq).index_by(&:id)
-    names = TagName.where(tag_id: target_ids.uniq, language_code: 'ja', primary_flg: true)
-        .pluck(:tag_id, :name).to_h
+    names =
+        TagName
+        .where(tag_id: target_ids.uniq,
+               language_code: locale.language_code,
+               primary_flg: true)
+        .pluck(:tag_id, :name)
+        .to_h
     child_groups = TagGroup.where(id: child_ids.uniq).index_by(&:id)
 
     groups.map do |group|
@@ -32,8 +43,8 @@ module TagGroupRepr
     end
   end
 
-  def one group
-    many([group]).first
+  def one locale, group
+    many(locale, [group]).first
   end
 
   def tag_group wiki_page
@@ -48,7 +59,7 @@ module TagGroupRepr
     TagGroupVersion.find_by(tag_group_id: group.id, version_no: group.version_no)
   end
 
-  def historical version
+  def historical locale, version
     members = Array(version.members)
     placements = Array(version.placements)
     tag_references = members.filter_map { |member| member['tag_id'] } +
@@ -68,10 +79,10 @@ module TagGroupRepr
       [member.fetch('tag_group_id'), member.fetch('version_no')]
     end.to_h
     historical_members = members.map do |member|
-      historical_member(member, tag_versions, group_versions)
+      historical_member(locale, member, tag_versions, group_versions)
     end
     historical_placements = placements.map do |node|
-      historical_placement(node, tag_versions, group_versions,
+      historical_placement(locale, node, tag_versions, group_versions,
                            tag_version_numbers, group_version_numbers)
     end
     { 'id' => version.tag_group_id,
@@ -89,7 +100,7 @@ module TagGroupRepr
   def group_json group, tag_members, group_members, rows, tags, names, child_groups
     tree = placement_tree(rows, tags, names, child_groups)
     members = tag_members.sort_by(&:tag_id).map do |member|
-      { 'tag' => tag_json(tags.fetch(member.tag_id), names.fetch(member.tag_id)) }
+      { 'tag' => tag_json(tags.fetch(member.tag_id), names[member.tag_id]) }
     end
     members.concat(group_members.sort_by(&:child_tag_group_id).map do |member|
       { 'tag_group' => group_json_reference(child_groups.fetch(member.child_tag_group_id)) }
@@ -115,7 +126,7 @@ module TagGroupRepr
     build = lambda do |parent|
       by_parent.fetch(parent, []).sort_by(&:position).map do |row|
         node = if row.tag_id
-          { 'tag' => tag_json(tags.fetch(row.tag_id), names.fetch(row.tag_id)) }
+          { 'tag' => tag_json(tags.fetch(row.tag_id), names[row.tag_id]) }
         elsif row.child_tag_group_id
           { 'tag_group' => group_json_reference(child_groups.fetch(row.child_tag_group_id)) }
         else
@@ -153,11 +164,11 @@ module TagGroupRepr
     end
   end
 
-  def historical_member member, tag_versions, group_versions
+  def historical_member locale, member, tag_versions, group_versions
     if member['tag_id']
       id = member.fetch('tag_id')
       version = tag_versions.fetch([id, member.fetch('version_no')])
-      { 'tag' => { 'id' => id, 'name' => japanese_version_name(version),
+      { 'tag' => { 'id' => id, 'name' => version_name(locale, version),
                    'category' => version.category } }
     else
       id = member.fetch('tag_group_id')
@@ -166,13 +177,13 @@ module TagGroupRepr
     end
   end
 
-  def historical_placement(node, tag_versions, group_versions,
-                           tag_version_numbers, group_version_numbers)
+  def historical_placement locale, node, tag_versions, group_versions,
+                           tag_version_numbers, group_version_numbers
     result = if node['tag_id']
       id = node.fetch('tag_id')
       version_no = tag_version_numbers.fetch(id)
       version = tag_versions.fetch([id, version_no])
-      { 'tag' => { 'id' => id, 'name' => japanese_version_name(version),
+      { 'tag' => { 'id' => id, 'name' => version_name(locale, version),
                    'category' => version.category } }
     elsif node['tag_group_id']
       id = node.fetch('tag_group_id')
@@ -183,12 +194,12 @@ module TagGroupRepr
       { 'section_name' => node.fetch('section_name'), 'description' => node['description'] }
     end
     result.merge('children' => Array(node['children']).map do |child|
-      historical_placement(child, tag_versions, group_versions,
+      historical_placement(locale, child, tag_versions, group_versions,
                            tag_version_numbers, group_version_numbers)
     end)
   end
 
-  def japanese_version_name version
-    version.names.fetch('ja').fetch('name')
+  def version_name locale, version
+    version.names[locale.language_code]&.fetch('name')
   end
 end

backend/app/representations/tag_repr.rb

@@ -3,21 +3,28 @@
 
 module TagRepr
   BASE = { only: [:id, :category, :post_count, :created_at, :updated_at, :deprecated_at],
-           methods: [:has_wiki, :material_id, :has_deerjikists] }.freeze
+           methods: [:material_id, :has_deerjikists] }.freeze
 
   module_function
 
   def base tag, language_code: 'ja'
-    tag.as_json(BASE).merge(name: name_for(tag, language_code),
+    tag.as_json(BASE).merge('has_wiki' => tag.has_description?(language_code:),
+                            name: name_for(tag, language_code),
                             aliases: tag.snapshot_aliases(language_code),
                             parents: tag.parents.map { inline(_1, language_code:) })
   end
 
   def inline tag, language_code: 'ja'
-    tag.as_json(BASE).merge(name: name_for(tag, language_code), aliases: [], parents: [])
+    tag.as_json(BASE).merge('has_wiki' => tag.has_description?(language_code:),
+                            name: name_for(tag, language_code), aliases: [], parents: [])
   end
 
-  def many(tags, language_code: 'ja') = tags.map { |tag| base(tag, language_code:) }
+  def many tags, language_code: 'ja'
+    records = tags.to_a
+    ActiveRecord::Associations::Preloader.new(
+        records:, associations: [:tag_descriptions, { parents: :tag_descriptions }]).call
+    records.map { |tag| base(tag, language_code:) }
+  end
 
   def name_for tag, language_code
     tag.name(language_code) || (tag.system? ? tag.name('ja') : nil)

backend/app/representations/wiki_page_repr.rb

@@ -2,18 +2,14 @@
 
 
 module WikiPageRepr
-  BASE = { methods: [:title, :deprecated_at] }.freeze
-
   module_function
 
-  def base wiki_page
-    wiki_page.as_json(BASE)
-  end
-
-  def tag_description description
+  def tag_description locale, description
     tag = description.tag
+
     { 'id' => description.id,
-      'tag_name_id' => tag.tag_name('ja')&.id,
+      'resource_type' => 'tag_description',
+      'tag_name_id' => tag.tag_name(locale.language_code)&.id,
       'body' => description.body,
       'created_user_id' => description.created_by_user_id,
       'updated_user_id' => description.updated_by_user_id,
@@ -21,15 +17,11 @@ module WikiPageRepr
       'updated_at' => description.updated_at,
       'discarded_at' => nil,
       'version_no' => description.version_no,
-      'title' => tag.name('ja'),
+      'title' => tag.name(locale.language_code),
       'deprecated_at' => tag.deprecated_at }
   end
 
   def tag_group tag_group
-    TagGroupRepr.tag_group(tag_group)
-  end
-
-  def many wiki_pages
-    wiki_pages.map { |p| base(p) }
+    TagGroupRepr.tag_group(tag_group).merge('resource_type' => 'tag_group')
   end
 end

backend/app/services/post_create_plan.rb

@@ -95,14 +95,10 @@ class PostCreatePlan
   def build_default_tag_specs locale, direct_tag_specs
     default_tag_specs = []
     if direct_tag_specs.length < 10 && direct_tag_specs.none? { _1[:name] == TAGME_TAG_NAME }
-      default_tag_specs << {
-          name: TAGME_TAG_NAME,
-          category: :meta }
+      default_tag_specs << { name: TAGME_TAG_NAME, category: :meta }
     end
     if direct_tag_specs.none? { deerjikist_tag_spec?(locale, _1) }
-      default_tag_specs << {
-          name: NO_DEERJIKIST_TAG_NAME,
-          category: :meta }
+      default_tag_specs << { name: NO_DEERJIKIST_TAG_NAME, category: :meta }
     end
 
     default_tag_specs
@@ -117,9 +113,9 @@ class PostCreatePlan
   end
 
   def validate_new_tag_spec! locale, spec
-    tag_name = TagName.new(name: spec[:name], language_code: locale.language_code,
-                           script_code: locale.script_code, primary_flg: true)
     tag = Tag.new(category: spec[:category])
+    tag_name = TagName.new(tag:, name: spec[:name], language_code: locale.language_code,
+                           script_code: locale.script_code, primary_flg: true)
     return if tag_name.valid? && tag.valid?
 
     post = Post.new
@@ -140,10 +136,10 @@ class PostCreatePlan
     end
     expanded_parent_specs =
         Tag.expand_parent_tags(existing_snapshot_tags)
-           .reject(&:deprecated?)
-           .map { |tag|
-             { name: tag.name(locale.language_code),
-               category: tag.category.to_sym }
+        .reject(&:deprecated?)
+        .map { |tag|
+          { name: tag.name(locale.language_code),
+            category: tag.category.to_sym }
         }
     merge_tag_specs(snapshot_tag_specs + expanded_parent_specs)
   end
@@ -164,9 +160,10 @@ class PostCreatePlan
   def existing_tags_by_name locale
     @existing_tags_by_name ||= begin
       names = tag_names.map { canonical_tag_name_without_sections(locale, _1) }.uniq
-      TagName.where(language_code: locale.language_code, primary_flg: true, name: names)
-             .includes(:tag)
-             .each_with_object({ }) { |tag_name, tags| tags[tag_name.name] = tag_name.tag }
+      TagName
+          .where(language_code: locale.language_code, primary_flg: true, name: names)
+          .includes(:tag)
+          .each_with_object({ }) { |tag_name, tags| tags[tag_name.name] = tag_name.tag }
     end
   end
 

backend/app/services/shared_resource_id_allocator.rb

@@ -0,0 +1,91 @@
+require 'digest'
+
+
+class SharedResourceIdAllocator
+  SPACES = {
+      'tags' => ['tags', 'external_tags'],
+      'wiki' => ['tag_descriptions', 'tag_groups'],
+      'wiki_history' => ['tag_description_versions', 'tag_group_versions'] }.freeze
+  HISTORY_IDS = {
+      'tags' => [
+          ['tag_versions', 'tag_id'],
+          ['nico_tag_versions', 'tag_id'],
+          ['tag_description_versions', 'tag_id']],
+      'wiki' => [['tag_group_versions', 'tag_group_id']] }.freeze
+  LOCK_TIMEOUT = 10
+
+  def self.assign! record
+    space, tables = SPACES.find { |_name, names| names.include?(record.class.table_name) }
+    raise ArgumentError, 'Unknown shared ID resource' unless tables
+
+    connection = record.class.connection
+    transaction = record.class.current_transaction
+    unless transaction.open?
+      raise ActiveRecord::ActiveRecordError, 'Shared ID requires a transaction'
+    end
+
+    database = connection.pool.db_config.database
+    name = "btrc:ids:#{ Digest::SHA256.hexdigest(database)[0, 16] }:#{ space }"
+    quoted_name = connection.quote(name)
+    acquired = record.class.uncached do
+      connection.select_value("SELECT GET_LOCK(#{ quoted_name }, #{ LOCK_TIMEOUT })")
+    end
+    unless acquired.to_i == 1
+      raise ActiveRecord::LockWaitTimeout, "Shared ID lock unavailable: #{ space }"
+    end
+
+    release = lambda do
+      result = record.class.uncached do
+        connection.select_value("SELECT RELEASE_LOCK(#{ quoted_name })")
+      end
+      unless result.to_i == 1
+        raise ActiveRecord::ActiveRecordError, "Shared ID lock release failed: #{ space }"
+      end
+    end
+    begin
+      transaction.after_commit(&release)
+      transaction.after_rollback(&release)
+    rescue StandardError
+      release.call
+      raise
+    end
+
+    # 明示-tic な Id. 指定は許可する．
+    return if record.id.present?
+
+    next_id = record.class.uncached do
+      historical_max = HISTORY_IDS.fetch(space, []).map { |table, column|
+        quoted_table = connection.quote_table_name(table)
+        quoted_column = connection.quote_column_name(column)
+        connection.select_value("SELECT MAX(#{ quoted_column }) FROM #{ quoted_table }").to_i
+      }.max.to_i
+
+      [next_ids(connection, tables).max, historical_max + 1].max
+    end
+
+    record.id = next_id
+  end
+
+  def self.next_ids connection, tables
+    expiry = connection.select_value('SELECT @@SESSION.information_schema_stats_expiry').to_i
+    begin
+      connection.execute('SET SESSION information_schema_stats_expiry = 0')
+      quoted_tables = tables.map { connection.quote(_1) }.join(', ')
+      rows = connection.select_all(<<~SQL).to_a
+        SELECT TABLE_NAME, ENGINE, AUTO_INCREMENT
+        FROM information_schema.tables
+        WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME IN (#{ quoted_tables })
+      SQL
+      persistent = rows.all? do |row|
+        row['ENGINE'] == 'InnoDB' && row['AUTO_INCREMENT'].to_i.positive?
+      end
+      unless rows.size == tables.size && persistent
+        raise ActiveRecord::ActiveRecordError, 'Persistent InnoDB counters are required'
+      end
+      rows.map { _1.fetch('AUTO_INCREMENT').to_i }
+    ensure
+      connection.execute("SET SESSION information_schema_stats_expiry = #{ expiry }")
+    end
+  end
+  private_class_method :next_ids
+end

backend/app/services/tag_description_operation.rb

@@ -1,54 +1,67 @@
 class TagDescriptionOperation
-  LANGUAGE_CODE = 'ja'
+  class Conflict < StandardError
+    ;
+  end
 
-  def self.create!(tag:, body:, created_by_user:, message: nil)
+  def self.create! locale, tag:, body:, created_by_user:, message: nil
     ApplicationRecord.transaction do
       tag.lock!
       raise ActiveRecord::RecordNotUnique if TagDescription.exists?(
-          tag_id: tag.id, language_code: LANGUAGE_CODE)
+          tag_id: tag.id, language_code: locale.language_code)
 
-      page = Wiki::CompatibilityWriter.create!(
-          tag_name: tag.tag_name(LANGUAGE_CODE), body:, created_by_user:, message:)
-      revision = page.wiki_revisions.order(id: :desc).first
-      record_version!(tag:, revision:, body:, user: created_by_user,
-                      description: nil)
-      page
+      description = TagDescription.new(tag:, language_code: locale.language_code)
+      body = normalise_body!(description, body)
+      record_version!(description:, body:, user: created_by_user)
+
+      description
     end
   end
 
-  def self.update!(tag:, body:, updated_by_user:, message: nil,
-                   base_revision_id: nil)
+  def self.update! locale, tag:, body:, updated_by_user:, message: nil, base_revision_id: nil
     ApplicationRecord.transaction do
       tag.lock!
       description = TagDescription.lock.find_by!(
-          tag_id: tag.id, language_code: LANGUAGE_CODE)
-      page = WikiPage.lock.find(description.id)
-      revision = Wiki::CompatibilityWriter.update!(
-          page:, body:, updated_by_user:, message:,
-          base_revision_id:)
-      next unless revision
+          tag_id: tag.id, language_code: locale.language_code)
+      body = normalise_body!(description, body)
+      latest = TagDescriptionVersion.find_by(
+          tag_id: tag.id, language_code: locale.language_code,
+          version_no: description.version_no)
+      if base_revision_id.present? && latest&.id != base_revision_id.to_i
+        raise Conflict, '競合が発生してゐます．'
+      end
+      next if latest && normalise_body(description.body) == body
 
-      record_version!(tag:, revision:, body: revision.body,
-                      user: updated_by_user, description:)
-      revision
+      record_version!(description:, body:, user: updated_by_user)
     end
   end
 
-  def self.record_version! tag:, revision:, body:, user:, description:
-    version_no = description ? description.version_no + 1 : 1
+  def self.record_version! description:, body:, user:
+    creating = description.new_record?
+    version_no = creating ? 1 : description.version_no + 1
+    description.created_by_user_id = user.id if creating
+    description.update!(body:, version_no:, updated_by_user_id: user.id)
     TagDescriptionVersion.create!(
-        id: revision.id, tag_id: tag.id, language_code: LANGUAGE_CODE,
-        version_no:, event_type: description ? 'update' : 'create', body:,
-        created_by_user_id: user.id, created_at: revision.created_at)
-    if description
-      description.update!(body:, version_no:, updated_by_user_id: user.id)
-    else
-      TagDescription.create!(
-          id: revision.wiki_page_id, tag_id: tag.id,
-          language_code: LANGUAGE_CODE, version_no:, body:,
-          created_by_user_id: user.id, updated_by_user_id: user.id)
-    end
+        tag_id: description.tag_id, language_code: description.language_code,
+        version_no:, event_type: creating ? 'create' : 'update', body:,
+        source_language_code: description.source_language_code,
+        source_version_no: description.source_version_no,
+        created_by_user_id: user.id, created_at: Time.current)
   end
-
   private_class_method :record_version!
+
+  def self.normalise_body body
+    body.to_s.gsub(/\r\n?/, "\n")
+        .encode('UTF-8', invalid: :replace, undef: :replace, replace: '🖕')
+        .sub(/\n+\z/, '')
+  end
+  private_class_method :normalise_body
+
+  def self.normalise_body! description, body
+    normalised = normalise_body(body)
+    return normalised if normalised.present?
+
+    description.errors.add(:body, :blank)
+    raise ActiveRecord::RecordInvalid, description
+  end
+  private_class_method :normalise_body!
 end

backend/app/services/tag_group_markdown_parser.rb

@@ -7,8 +7,8 @@ class TagGroupMarkdownParser
     ;
   end
 
-  def self.parse(body:, group: nil)
-    new(body:, group:).parse
+  def self.parse(locale, body:, group: nil)
+    new(body:, group:).parse(locale)
   end
 
   def initialize(body:, group:)
@@ -16,7 +16,7 @@ class TagGroupMarkdownParser
     @group = group
   end
 
-  def parse
+  def parse locale
     parse_body = @body.gsub(/([^\n])\n([\x23]{1,6}[ \t]+\S)/, "\\1\n\n\\2")
     root = Kramdown::Document.new(parse_body, input: 'GFM', auto_ids: false).root
     placements = []
@@ -51,7 +51,7 @@ class TagGroupMarkdownParser
       when :ul
         invalid!('未対応のリスト項目があります．') if node.attr.any?
         target = headings.any? ? headings.last.fetch(:node).fetch('children') : placements
-        target.concat(node.children.map { parse_list_item(_1) })
+        target.concat(node.children.map { parse_list_item(locale, _1) })
       else
         invalid!("未対応の Markdown 構文 #{ node.type.inspect } です．")
       end
@@ -66,7 +66,7 @@ class TagGroupMarkdownParser
 
   private
 
-  def parse_list_item(item)
+  def parse_list_item locale, item
     invalid!('リスト項目ではありません．') unless item.type == :li
     invalid!('未対応のリスト項目があります．') if item.attr.any?
 
@@ -81,29 +81,30 @@ class TagGroupMarkdownParser
     label = own.map { inline_text(_1) }.join(' ').strip
     invalid!('空のリスト項目は使用できません．') if label.blank?
 
-    node = if label.start_with?(PREFIX)
-      group_name = label.delete_prefix(PREFIX).strip
-      child_group = TagGroup.find_by(name: group_name)
-      invalid!("Tag Group #{ group_name.inspect } を解決できません．") unless child_group
-      invalid!('自分自身を含めることはできません．') if child_group.id == @group&.id
-      { 'tag_group_id' => child_group.id }
-    elsif label.end_with?(':', '：')
-      section_name = label.sub(/[:：]\z/, '').strip
-      invalid!('Section 名は必須です．') if section_name.blank?
-      { 'section_name' => section_name, 'description' => nil }
-    else
-      { 'tag_id' => resolve_tag(label) }
-    end
+    node =
+        if (group_name = TagGroupRepr.name_from_title(label))
+          group_name = group_name.strip
+          child_group = TagGroup.find_by(name: group_name)
+          invalid!("Tag Group #{ group_name.inspect } を解決できません．") unless child_group
+          invalid!('自分自身を含めることはできません．') if child_group.id == @group&.id
+          { 'tag_group_id' => child_group.id }
+        elsif label.end_with?(':', '：')
+          section_name = label.sub(/[:：]\z/, '').strip
+          invalid!('Section 名は必須です．') if section_name.blank?
+          { 'section_name' => section_name, 'description' => nil }
+        else
+          { 'tag_id' => resolve_tag(locale, label) }
+        end
 
     node['children'] = nested.flat_map do |list|
       invalid!('未対応の入れ子リストです．') unless list.type == :ul
-      list.children.map { parse_list_item(_1) }
+      list.children.map { parse_list_item(locale, _1) }
     end
     node
   end
 
-  def resolve_tag(name)
-    names = TagName.where(language_code: 'ja', name:).to_a
+  def resolve_tag locale, name
+    names = TagName.where(language_code: locale.language_code, name:).to_a
     tag_ids = names.filter_map(&:tag_id).uniq
     invalid!("Tag #{ name.inspect } を解決できません．") if tag_ids.empty?
     invalid!("Tag 名 #{ name.inspect } が曖昧です．") if tag_ids.many?

backend/app/services/tag_group_markdown_renderer.rb

@@ -19,15 +19,20 @@ class TagGroupMarkdownRenderer
       blocks << clean_text(@group['description'])
     end
 
-    sections = placements.select { _1.key?('section_name') }
-    if sections.any? && sections.size != placements.size
-      raise UnsupportedStructure,
-          '最上位の見出し Section と Placement の混在は Markdown にできません．'
-    end
+    first_section = placements.index { _1.key?('section_name') }
 
-    if placements.all? { _1.key?('section_name') }
-      blocks.concat(placements.map { render_heading(_1, 2) })
-    else
+    if first_section
+      if placements.drop(first_section).any? { !_1.key?('section_name') }
+        raise UnsupportedStructure,
+            '見出し Section の後に最上位 Placement は配置できません．'
+      end
+
+      if first_section.positive?
+        blocks << render_list(placements.take(first_section), 0)
+      end
+
+      blocks.concat(placements.drop(first_section).map { render_heading(_1, 2) })
+    elsif placements.any?
       blocks << render_list(placements, 0)
     end
 
@@ -74,7 +79,7 @@ class TagGroupMarkdownRenderer
       first_section = section_indexes.first
       if children[first_section..].any? { !_1.key?('section_name') }
         raise UnsupportedStructure,
-            '見出し Section と兄弟 Placement の交互配置は Markdown にできません．'
+              '見出し Section と兄弟 Placement の交互配置は Markdown にできません．'
       end
       list_nodes = children[0...first_section]
       blocks << render_list(list_nodes, 0) if list_nodes.any?

backend/app/services/tag_group_operation.rb

@@ -1,49 +1,51 @@
 class TagGroupOperation
   MAX_PLACEMENT_DEPTH = 5
-  PREFIX = TagGroupRepr::PREFIX
 
-  def self.create!(name:, description:, members:, placements:, actor:,
-                   require_compatibility: false, compatibility_body: nil)
-    group, sync_issue = ApplicationRecord.transaction do
+  def self.create!(locale, name:, description:, members:, placements:, actor:,
+                   require_compatibility: false)
+    ApplicationRecord.transaction do
       group = TagGroup.new(version_no: 1, created_by_user: actor,
                            updated_by_user: actor)
-      attributes = prepare!(group:, name:, description:, members:, placements:)
+      attributes = prepare!(locale:, group:, name:, description:, members:, placements:)
       group.assign_attributes(name: attributes.fetch(:name),
                               description: attributes.fetch(:description))
       group.save!
       persist_structure!(group:, attributes:, actor:)
+      validate_compatibility!(locale, group) if require_compatibility
       persist_version!(group:, attributes:, actor:, event_type: 'create')
-      issue = sync_compatibility!(group:, actor:, old_name: nil,
-                                  require_compatibility:, compatibility_body:)
-      [group, issue]
+      group
     end
-    report_sync_issue(group, actor, sync_issue)
-    group
   end
 
-  def self.update!(group:, name:, description:, members:, placements:, actor:,
-                   require_compatibility: false, compatibility_body: nil)
-    group, sync_issue = ApplicationRecord.transaction do
+  def self.update!(locale, group:, name:, description:, members:, placements:, actor:,
+                   require_compatibility: false)
+    ApplicationRecord.transaction do
       group.lock!
-      old_name = group.name
-      attributes = prepare!(group:, name:, description:, members:, placements:)
-      next [group, nil] if unchanged?(group, attributes)
+      attributes = prepare!(locale:, group:, name:, description:, members:, placements:)
+      if unchanged?(group, attributes)
+        validate_compatibility!(locale, group) if require_compatibility
+        next group
+      end
 
       group.update!(name: attributes.fetch(:name),
                     description: attributes.fetch(:description),
                     version_no: group.version_no + 1,
                     updated_by_user: actor)
       persist_structure!(group:, attributes:, actor:)
+      validate_compatibility!(locale, group) if require_compatibility
       persist_version!(group:, attributes:, actor:, event_type: 'update')
-      issue = sync_compatibility!(group:, actor:, old_name:,
-                                  require_compatibility:, compatibility_body:)
-      [group, issue]
+      group
     end
-    report_sync_issue(group, actor, sync_issue)
-    group
   end
 
-  def self.prepare!(group:, name:, description:, members:, placements:)
+  def self.validate_compatibility! locale, group
+    TagGroupMarkdownRenderer.render(TagGroupRepr.one(locale, group))
+  rescue TagGroupMarkdownRenderer::UnsupportedStructure => error
+    invalid!(group, :base, error.message)
+  end
+  private_class_method :validate_compatibility!
+
+  def self.prepare!(locale:, group:, name:, description:, members:, placements:)
     record = group
     normalized_name = name.to_s.strip
     invalid!(record, :name, 'グループ名は必須です．') if normalized_name.blank?
@@ -61,7 +63,7 @@ class TagGroupOperation
 
     member_rows = normalize_members(record, members)
     placement_tree = normalize_placements(record, placements)
-    validate_references!(record, member_rows, placement_tree)
+    validate_references!(locale, record, member_rows, placement_tree)
     validate_containment!(record, member_rows)
     { name: normalized_name, description:, members: member_rows,
       placements: placement_tree }
@@ -185,7 +187,7 @@ class TagGroupOperation
   end
   private_class_method :normalize_placement_nodes
 
-  def self.validate_references!(record, members, placements)
+  def self.validate_references!(locale, record, members, placements)
     membership = members.to_set
     placed = placement_references(placements).uniq
     missing = placed - membership.to_a
@@ -204,13 +206,14 @@ class TagGroupOperation
     tag_versions = TagVersion.where(tag_id: tag_ids).pluck(:tag_id, :version_no).to_set
     group_versions = TagGroupVersion.where(tag_group_id: group_ids)
         .pluck(:tag_group_id, :version_no).to_set
-    tag_names = TagName.where(tag_id: tag_ids, language_code: 'ja', primary_flg: true)
+    tag_names = TagName.where(
+        tag_id: tag_ids, language_code: locale.language_code, primary_flg: true)
         .pluck(:tag_id).uniq
 
     members.each do |member|
       if member.key?('tag_id')
         id = member.fetch('tag_id')
-        invalid!(record, :members, "Tag ##{ id } に日本語の正規名がありません．") unless
+        invalid!(record, :members, :invalid) unless
             tag_names.include?(id)
         version_no = tags.fetch(id).version_no
         unless tag_versions.include?([id, version_no])
@@ -313,57 +316,6 @@ class TagGroupOperation
   end
   private_class_method :persist_version!
 
-  def self.sync_compatibility!(group:, actor:, old_name:,
-                               require_compatibility:, compatibility_body:)
-    representation = TagGroupRepr.one(group)
-    body = begin
-      TagGroupMarkdownRenderer.render(representation)
-    rescue TagGroupMarkdownRenderer::UnsupportedStructure => error
-      if compatibility_body.present?
-        compatibility_body
-      elsif require_compatibility
-        invalid!(group, :base, error.message)
-      else
-        return error.message
-      end
-    end
-    invalid!(group, :base, '本文は必須です．') if body.blank?
-
-    title = "#{ PREFIX }#{ group.name }"
-    old_title = old_name && "#{ PREFIX }#{ old_name }"
-    page = if old_title
-      WikiPage.joins(:tag_name).find_by(tag_names: { name: old_title })
-    else
-      nil
-    end
-    page ||= WikiPage.joins(:tag_name).find_by(tag_names: { name: title })
-
-    if page
-      tag_name = page.tag_name
-      tag_name.update!(name: title) if tag_name.name != title
-      Wiki::Commit.legacy_content!(page:, body:, created_user: actor, message: nil,
-                                   base_revision_id: nil)
-    else
-      tag_name = TagName.find_or_initialize_by(language_code: 'ja', name: title)
-      tag_name.script_code = 'Jpan'
-      tag_name.primary_flg = true
-      tag_name.auto_generated = false
-      tag_name.save!
-      Wiki::Commit.create_legacy_content!(tag_name:, body:, created_by_user: actor)
-    end
-    nil
-  end
-  private_class_method :sync_compatibility!
-
-  def self.report_sync_issue(group, actor, reason)
-    return unless reason
-
-    payload = { status: 'unsupported_structure', tag_group_id: group.id,
-                version_no: group.version_no, user_id: actor&.id, reason: }
-    Rails.logger.warn("tag_group_wiki_sync_skipped #{ payload.to_json }")
-  end
-  private_class_method :report_sync_issue
-
   def self.placement_references(nodes)
     nodes.flat_map do |node|
       own = if node.key?('tag_id')

backend/app/services/tag_name_completion.rb

@@ -0,0 +1,47 @@
+class TagNameCompletion
+  class << self
+    def for_locale! locale
+      named_tags =
+          TagName.where(language_code: locale.language_code, primary_flg: true)
+          .select(:tag_id)
+      Tag.where.not(id: named_tags).find_each do |tag|
+        for_tag!(tag, locales: [locale])
+      end
+    end
+
+    def for_tag! tag, locales: nil
+      locales ||= Locale.where(deprecated_at: nil).order(:language_code, :created_at, :script_code)
+      tag.with_lock do
+        primary_names = tag.tag_names.where(primary_flg: true).index_by(&:language_code)
+        locales.to_a.uniq(&:language_code).each do |locale|
+          next if primary_names.key?(locale.language_code)
+
+          name = TagName.generate_name(locale, tag, primary_names['ja'])
+          primary_names[locale.language_code] = create_name!(locale, tag, name)
+        end
+        tag.association(:tag_names).reset
+      end
+    end
+
+    private
+
+    def create_name! locale, tag, name
+      persist_name!(locale, tag, name)
+    rescue ActiveRecord::RecordNotUnique, ActiveRecord::RecordInvalid => error
+      fallback = "Tag_##{ tag.id }"
+      collision =
+          error.is_a?(ActiveRecord::RecordNotUnique) ||
+          error.record.errors.of_kind?(:name, :taken)
+      raise if name == fallback || !(collision)
+
+      persist_name!(locale, tag, fallback)
+    end
+
+    def persist_name! locale, tag, name
+      TagName.transaction(requires_new: true) do
+        TagName.create!(tag:, name:, language_code: locale.language_code,
+                        script_code: locale.script_code, primary_flg: true, auto_generated: true)
+      end
+    end
+  end
+end

backend/app/services/tag_name_transcription.rb

@@ -0,0 +1,56 @@
+module TagNameTranscription
+  class Unconvertible < StandardError
+    ;
+  end
+
+  def self.ainu name
+    previous_script = nil
+    parts = []
+    NipponeseSegments.split(name).each do |script, text|
+      output = transcribe_segment(script, text)
+      if (parts.last && output.first && previous_script && script != previous_script &&
+          NipponeseSegments.nipponese?(previous_script) && NipponeseSegments.nipponese?(script))
+        parts << '_'
+      end
+
+      parts.concat(output)
+      previous_script = script
+    end
+
+    replace_unconvertible(parts)
+  end
+
+  def self.transcribe_segment script, text
+    return [text] if script == :literal
+    return [nil] if script == :unconvertible
+    return transcribe_reading(text) unless script == :kanzi
+
+    text.each_char.flat_map do |character|
+      transcribe_reading(JisReadings.read(character))
+    rescue Unconvertible
+      [nil]
+    end
+  end
+
+  def self.transcribe_reading reading
+    Phonology.adapt(reading).map do |sound|
+      sound && Katakana.render([sound])
+    rescue Unconvertible
+      nil
+    end
+  end
+
+  def self.replace_unconvertible parts
+    grouped = parts.chunk { _1.nil? }.flat_map { |unconvertible, group|
+      unconvertible ? [nil] : group
+    }
+    first = grouped.index { _1&.match?(/[^_]/) }
+    last = grouped.rindex { _1&.match?(/[^_]/) }
+
+    grouped.each_with_index.map { |part, index|
+      part || (first && first < index && index < last ? '_' : '')
+    }.join
+  end
+
+  private_class_method :transcribe_segment, :transcribe_reading, :replace_unconvertible
+end

backend/app/services/tag_name_transcription/jis_readings.rb

@@ -0,0 +1,13 @@
+module TagNameTranscription
+  module JisReadings
+    SOURCE = Rails.root.join('config/tag_name_readings/jis_level_one.tsv')
+    READINGS = File.foreach(SOURCE, chomp: true).reject { _1.start_with?('#') }.to_h { |line|
+      character, reading, = line.split("\t")
+      [character, reading]
+    }.freeze
+
+    def self.read text
+      text.each_char.map { READINGS.fetch(_1) { raise Unconvertible } }.join
+    end
+  end
+end

backend/app/services/tag_name_transcription/katakana.rb

@@ -0,0 +1,26 @@
+module TagNameTranscription
+  module Katakana
+    ROWS = {
+        '' => 'アイウエオ',
+        'k' => 'カキクケコ',
+        's' => 'サシスセソ',
+        'c' => ['チャ', 'チ', 'チュ', 'チェ', 'チョ'],
+        't' => ['タ', 'ティ', 'トゥ', 'テ', 'ト'],
+        'n' => 'ナニヌネノ',
+        'h' => 'ハヒフヘホ',
+        'p' => 'パピプペポ',
+        'm' => 'マミムメモ',
+        'r' => 'ラリルレロ' }.freeze
+    SYLLABLES = ROWS.flat_map { |onset, letters|
+      kana = letters.is_a?(String) ? letters.chars : letters
+      ['a', 'i', 'u', 'e', 'o'].zip(kana).map { |vowel, letter| [onset + vowel, letter] }
+    }.to_h.merge(
+        'ya' => 'ヤ', 'yu' => 'ユ', 'yo' => 'ヨ', 'wa' => 'ワ',
+        'k' => 'ㇰ', 's' => 'ㇱ', 't' => 'ッ', 'n' => 'ン', 'm' => 'ㇺ', 'p' => 'ㇷ゚',
+        'r:a' => 'ㇻ', 'r:i' => 'ㇼ', 'r:u' => 'ㇽ', 'r:e' => 'ㇾ', 'r:o' => 'ㇿ').freeze
+
+    def self.render sounds
+      sounds.map { SYLLABLES.fetch(_1) { raise Unconvertible } }.join
+    end
+  end
+end

backend/app/services/tag_name_transcription/nipponese_segments.rb

@@ -0,0 +1,30 @@
+module TagNameTranscription
+  module NipponeseSegments
+    NIPPONESE_SCRIPTS = [:kanzi, :xiragana, :katakana].freeze
+
+    def self.nipponese?(script) = NIPPONESE_SCRIPTS.include?(script)
+
+    def self.split name
+      segments = []
+      name.to_s.scan(/\X/).each do |character|
+        script = classify(character, segments.last&.first)
+        if segments.last&.first == script
+          segments.last[1] << character
+        else
+          segments << [script, character.dup]
+        end
+      end
+      segments
+    end
+
+    def self.classify character, previous_script
+      return previous_script if character == 'ー' && nipponese?(previous_script)
+      return :kanzi if character.match?(/\A\p{Han}\z/)
+      return :xiragana if character.match?(/\A\p{Hiragana}\p{M}*\z/)
+      return :katakana if character.match?(/\A\p{Katakana}\p{M}*\z/)
+      return :literal if character.match?(/\A(?:\p{Latin}\p{M}*|[!-~])\z/)
+
+      :unconvertible
+    end
+  end
+end

backend/app/services/tag_name_transcription/phonology.rb

@@ -0,0 +1,59 @@
+module TagNameTranscription
+  module Phonology
+    ROWS = {
+        'アイウエオ' => ['a', 'i', 'u', 'e', 'o'],
+        'カキクケコ' => ['ka', 'ki', 'ku', 'ke', 'ko'],
+        'ガギグゲゴ' => ['ka', 'ki', 'ku', 'ke', 'ko'],
+        'サシスセソ' => ['sa', 'si', 'su', 'se', 'so'],
+        'ザジズゼゾ' => ['ca', 'ci', 'cu', 'ce', 'co'],
+        'タチツテト' => ['ta', 'ci', 'cu', 'te', 'to'],
+        'ダヂヅデド' => ['ta', 'ci', 'cu', 'te', 'to'],
+        'ナニヌネノ' => ['na', 'ni', 'nu', 'ne', 'no'],
+        'ハヒフヘホ' => ['ha', 'hi', 'hu', 'he', 'ho'],
+        'バビブベボ' => ['pa', 'pi', 'pu', 'pe', 'po'],
+        'パピプペポ' => ['pa', 'pi', 'pu', 'pe', 'po'],
+        'マミムメモ' => ['ma', 'mi', 'mu', 'me', 'mo'],
+        'ヤユヨ' => ['ya', 'yu', 'yo'],
+        'ラリルレロ' => ['ra', 'ri', 'ru', 're', 'ro'],
+        'ワ' => ['wa'],
+        'ン' => ['n'],
+        'ッ' => ['t'],
+        'ㇰ' => ['k'],
+        'ㇱㇲ' => ['s', 's'],
+        'ㇳ' => ['t'],
+        'ㇴ' => ['n'],
+        'ㇺ' => ['m'],
+        'ㇻㇼㇽㇾㇿ' => ['r:a', 'r:i', 'r:u', 'r:e', 'r:o'] }.freeze
+
+    SOUNDS = ROWS.flat_map { |characters, sounds| characters.chars.zip(sounds) }.to_h.freeze
+
+    DIGRAPHS = {
+        'シャ' => 'sa', 'シュ' => 'su', 'シェ' => 'se', 'ショ' => 'so',
+        'チャ' => 'ca', 'チュ' => 'cu', 'チェ' => 'ce', 'チョ' => 'co',
+        'ジャ' => 'ca', 'ジュ' => 'cu', 'ジェ' => 'ce', 'ジョ' => 'co',
+        'ヂャ' => 'ca', 'ヂュ' => 'cu', 'ヂェ' => 'ce', 'ヂョ' => 'co' }.freeze
+
+    def self.adapt reading
+      kana = reading.unicode_normalize(:nfc).tr('ぁ-ゖ', 'ァ-ヶ').delete('ー')
+      characters = kana.scan(/\X/)
+      sounds = []
+      index = 0
+
+      while index < characters.length
+        pair = characters[index, 2].join
+
+        if DIGRAPHS.key?(pair)
+          sounds << DIGRAPHS.fetch(pair)
+          index += 2
+          next
+        end
+
+        character = characters[index].tr('ャュョ', 'ヤユヨ')
+        sounds << (character == 'ㇷ゚' ? 'p' : SOUNDS[character])
+        index += 1
+      end
+
+      sounds
+    end
+  end
+end

backend/app/services/wiki/commit.rb

@@ -1,160 +0,0 @@
-require 'digest'
-
-
-module Wiki
-  class Commit
-    class Conflict < StandardError
-      ;
-    end
-
-    def self.create_content! tag_name:, body:, created_by_user:, message: nil
-      if tag_name.tag && tag_name.language_code == 'ja'
-        return TagDescriptionOperation.create!(
-            tag: tag_name.tag, body:, created_by_user:, message:)
-      end
-
-      create_legacy_content!(tag_name:, body:, created_by_user:, message:)
-    end
-
-    def self.create_legacy_content! tag_name:, body:, created_by_user:, message: nil
-      normalised = normalise_body(body)
-
-      page = WikiPage.new(tag_name:,
-                          body: normalised,
-                          created_user: created_by_user,
-                          updated_user: created_by_user)
-
-      if normalised.blank?
-        page.errors.add(:body, :blank)
-        raise ActiveRecord::RecordInvalid, page
-      end
-
-      ActiveRecord::Base.transaction do
-        page.save!
-
-        new(page:, created_user: created_by_user).content!(
-            body: normalised,
-            message:,
-            base_revision_id: nil)
-
-        page
-      end
-    end
-
-    def self.content! page:, body:, created_user:, message: nil, base_revision_id: nil
-      description = TagDescription.find_by(id: page.id)
-      if description
-        return TagDescriptionOperation.update!(
-            tag: description.tag, body:, updated_by_user: created_user,
-            message:, base_revision_id:)
-      end
-
-      legacy_content!(page:, body:, created_user:, message:, base_revision_id:)
-    end
-
-    def self.legacy_content! page:, body:, created_user:, message: nil,
-                             base_revision_id: nil
-      new(page:, created_user:).content!(body:, message:, base_revision_id:)
-    end
-
-    def self.redirect! page:, redirect_page:, created_user:, message: nil, base_revision_id: nil
-      new(page:, created_user:).redirect!(redirect_page:, message:, base_revision_id:)
-    end
-
-    def initialize page:, created_user:
-      @page = page
-      @created_user = created_user
-    end
-
-    def content! body:, message:, base_revision_id:
-      normalised = self.class.normalise_body(body)
-      if normalised.blank?
-        @page.errors.add(:body, :blank)
-        raise ActiveRecord::RecordInvalid, @page
-      end
-
-      lines = split_lines(normalised)
-
-      line_shas = lines.map { |line| Digest::SHA256.hexdigest(line) }
-      tree_sha = Digest::SHA256.hexdigest(line_shas.join(','))
-
-      ActiveRecord::Base.transaction do
-        @page.lock!
-
-        if base_revision_id.present?
-          current_id = @page.wiki_revisions.maximum(:id)
-          if current_id && current_id != base_revision_id.to_i
-            raise Conflict,
-                "競合が発生してゐます" +
-                "（現在の Id.：#{ current_id }，ベース Id.：#{ base_revision_id }）．"
-          end
-        end
-
-        line_id_by_sha = upsert_lines!(lines, line_shas)
-        line_ids = line_shas.map { |sha| line_id_by_sha.fetch(sha) }
-        @page.update!(body: normalised)
-
-        WikiVersionRecorder.record!(
-            page: @page,
-            event_type: @page.wiki_versions.exists? ? :update : :create,
-            reason: message,
-            created_by_user: @created_user)
-
-        rev = WikiRevision.create!(
-            wiki_page:        @page,
-            base_revision_id:,
-            created_user:     @created_user,
-            kind:             :content,
-            redirect_page_id: nil,
-            message:,
-            lines_count:      lines.length,
-            tree_sha256:      tree_sha)
-
-        rows = line_ids.each_with_index.map do |line_id, pos|
-          { wiki_revision_id: rev.id, wiki_line_id: line_id, position: pos }
-        end
-        WikiRevisionLine.insert_all!(rows) if rows.any?
-        rev
-      end
-    end
-
-    def redirect!(redirect_page:, message:, base_revision_id:) = raise '廃止しました．'
-
-    def self.normalise_body body
-      s = body.to_s
-      s.gsub!(/\r\n?/, "\n")
-      s.encode('UTF-8', invalid: :replace, undef: :replace, replace: '🖕')
-      s.gsub(/\n+$/, '')
-    end
-
-    private
-
-    def split_lines(body) = body.split("\n")
-
-    def upsert_lines! lines, line_shas
-      now = Time.current
-
-      id_by_sha = WikiLine.where(sha256: line_shas).pluck(:sha256, :id).to_h
-
-      missing_by_sha = { }
-
-      line_shas.each_with_index do |sha, i|
-        next if id_by_sha.key?(sha)
-        next if missing_by_sha.key?(sha)
-
-        missing_by_sha[sha] = {
-            sha256:     sha,
-            body:       lines[i],
-            created_at: now,
-            updated_at: now }
-      end
-
-      if missing_by_sha.any?
-        WikiLine.upsert_all(missing_by_sha.values)
-        id_by_sha = WikiLine.where(sha256: line_shas).pluck(:sha256, :id).to_h
-      end
-
-      id_by_sha
-    end
-  end
-end

backend/app/services/wiki/compatibility_writer.rb

@@ -1,33 +0,0 @@
-module Wiki
-  class CompatibilityWriter
-    def self.create! tag_name:, body:, created_by_user:, message: nil
-      Commit.create_legacy_content!(
-          tag_name:, body:, created_by_user:, message:)
-    end
-
-    def self.update! page:, body:, updated_by_user:, message: nil,
-                     base_revision_id: nil
-      normalised = Commit.normalise_body(body)
-      if normalised.blank?
-        return Commit.legacy_content!(
-            page:, body: normalised, created_user: updated_by_user, message:,
-            base_revision_id:)
-      end
-
-      if base_revision_id.present?
-        current_id = page.wiki_revisions.maximum(:id)
-        if current_id && current_id != base_revision_id.to_i
-          raise Commit::Conflict,
-              "競合が発生してゐます" +
-              "（現在の Id.：#{ current_id }，ベース Id.：#{ base_revision_id }）．"
-        end
-      end
-
-      return if Commit.normalise_body(page.body) == normalised
-
-      Commit.legacy_content!(
-          page:, body: normalised, created_user: updated_by_user, message:,
-          base_revision_id:)
-    end
-  end
-end

backend/app/services/wiki_version_recorder.rb

@@ -1,21 +0,0 @@
-class WikiVersionRecorder < VersionRecorder
-  def self.record! page:, event_type:, reason: nil, created_by_user:
-    new(page:, event_type:, reason:, created_by_user:).record!
-  end
-
-  def initialize page:, event_type:, reason: nil, created_by_user:
-    @reason = reason
-    super(record: page, event_type:, created_by_user:)
-  end
-
-  private
-
-  def version_class = WikiVersion
-  def version_association = :wiki_versions
-  def record_key = :wiki_page
-
-  def snapshot_attributes = {
-      title: @record.title,
-      body: @record.body,
-      reason: @reason }
-end

backend/config/routes.rb

@@ -1,4 +1,6 @@
 Rails.application.routes.draw do
+  resources :locales, only: [:index]
+
   resources :tag_groups, only: [:index, :show, :create, :update]
 
   resources :nico_tags, path: 'tags/nico', only: [:index, :show, :update]

backend/db/migrate/20261015000000_drop_wiki_pages.rb

@@ -0,0 +1,9 @@
+class DropWikiPages < ActiveRecord::Migration[8.0]
+  def change
+    drop_table :wiki_versions
+    drop_table :wiki_revision_lines
+    drop_table :wiki_lines
+    drop_table :wiki_revisions
+    drop_table :wiki_pages
+  end
+end

backend/db/migrate/20261015003000_remove_tag_name_id_from_tags.rb

@@ -0,0 +1,11 @@
+class RemoveTagNameIdFromTags < ActiveRecord::Migration[8.0]
+  def up
+    remove_foreign_key :tags, column: :tag_name_id
+    remove_foreign_key :tag_names, column: :canonical_id
+
+    remove_column :tags, :tag_name_id
+    remove_column :tag_names, :canonical_id
+  end
+
+  def down = raise ActiveRecord::IrreversibleMigration, '戻せません．'
+end

backend/db/migrate/20261015010000_delete_name_for_wiki_from_tag_names.rb

@@ -0,0 +1,15 @@
+class DeleteNameForWikiFromTagNames < ActiveRecord::Migration[8.0]
+  def up
+    execute <<~SQL
+      DELETE
+      FROM
+        tag_names
+      WHERE
+        tag_id IS NULL
+    SQL
+
+    change_column_null :tag_names, :tag_id, false
+  end
+
+  def down = raise ActiveRecord::IrreversibleMigration, '戻せません．'
+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_10_08_010000) 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
@@ -578,17 +578,15 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_08_010000) do
   end
 
   create_table "tag_names", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.bigint "tag_id"
+    t.bigint "tag_id", null: false
     t.string "language_code", limit: 16, null: false
     t.string "name", null: false
     t.string "script_code", limit: 4, null: false
     t.boolean "primary_flg", null: false
     t.boolean "auto_generated", default: false, null: false
-    t.bigint "canonical_id"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.virtual "primary_tag_id", type: :bigint, as: "(case when `primary_flg` then `tag_id` else NULL end)"
-    t.index ["canonical_id"], name: "index_tag_names_on_canonical_id"
     t.index ["language_code", "name"], name: "index_tag_names_on_language_code_and_name", unique: true
     t.index ["primary_tag_id", "language_code"], name: "index_tag_names_on_primary_tag_id_and_language_code", unique: true
     t.index ["script_code"], name: "fk_rails_dd783b3d1c"
@@ -625,7 +623,6 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_08_010000) do
   end
 
   create_table "tags", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.bigint "tag_name_id", null: false
     t.string "category", default: "general", null: false
     t.datetime "deprecated_at"
     t.datetime "created_at", null: false
@@ -633,7 +630,6 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_08_010000) 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 ["tag_name_id"], name: "index_tags_on_tag_name_id", unique: true
     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
@@ -773,76 +769,6 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_08_010000) do
     t.index ["banned_at"], name: "index_users_on_banned_at"
   end
 
-  create_table "wiki_lines", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.string "sha256", limit: 64, null: false
-    t.text "body", null: false
-    t.datetime "created_at", null: false
-    t.datetime "updated_at", null: false
-    t.index ["sha256"], name: "index_wiki_lines_on_sha256", unique: true
-  end
-
-  create_table "wiki_pages", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.bigint "tag_name_id", null: false
-    t.text "body", null: false
-    t.bigint "created_user_id", null: false
-    t.bigint "updated_user_id", null: false
-    t.datetime "created_at", null: false
-    t.datetime "updated_at", null: false
-    t.datetime "discarded_at"
-    t.integer "version_no", null: false
-    t.index ["created_user_id"], name: "index_wiki_pages_on_created_user_id"
-    t.index ["discarded_at"], name: "index_wiki_pages_on_discarded_at"
-    t.index ["tag_name_id"], name: "index_wiki_pages_on_tag_name_id", unique: true
-    t.index ["updated_user_id"], name: "index_wiki_pages_on_updated_user_id"
-    t.check_constraint "`version_no` > 0", name: "chk_wiki_pages_version_no_positive"
-  end
-
-  create_table "wiki_revision_lines", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.bigint "wiki_revision_id", null: false
-    t.integer "position", null: false
-    t.bigint "wiki_line_id", null: false
-    t.index ["wiki_line_id"], name: "index_wiki_revision_lines_on_wiki_line_id"
-    t.index ["wiki_revision_id", "position"], name: "index_wiki_revision_lines_on_wiki_revision_id_and_position", unique: true
-    t.index ["wiki_revision_id", "wiki_line_id"], name: "index_wiki_revision_lines_on_wiki_revision_id_and_wiki_line_id"
-    t.index ["wiki_revision_id"], name: "index_wiki_revision_lines_on_wiki_revision_id"
-  end
-
-  create_table "wiki_revisions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.bigint "wiki_page_id", null: false
-    t.bigint "base_revision_id"
-    t.bigint "created_user_id", null: false
-    t.integer "kind", default: 0, null: false
-    t.bigint "redirect_page_id"
-    t.string "message"
-    t.integer "lines_count", default: 0, null: false
-    t.string "tree_sha256", limit: 64
-    t.datetime "created_at", null: false
-    t.datetime "updated_at", null: false
-    t.index ["base_revision_id"], name: "index_wiki_revisions_on_base_revision_id"
-    t.index ["created_user_id"], name: "index_wiki_revisions_on_created_user_id"
-    t.index ["kind"], name: "index_wiki_revisions_on_kind"
-    t.index ["redirect_page_id"], name: "index_wiki_revisions_on_redirect_page_id"
-    t.index ["tree_sha256"], name: "index_wiki_revisions_on_tree_sha256"
-    t.index ["wiki_page_id", "id"], name: "index_wiki_revisions_on_wiki_page_id_and_id"
-    t.index ["wiki_page_id"], name: "index_wiki_revisions_on_wiki_page_id"
-  end
-
-  create_table "wiki_versions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.bigint "wiki_page_id", null: false
-    t.integer "version_no", null: false
-    t.string "event_type", null: false
-    t.string "title", null: false
-    t.text "body", null: false
-    t.text "reason"
-    t.datetime "created_at", null: false
-    t.bigint "created_by_user_id"
-    t.index ["created_by_user_id"], name: "index_wiki_versions_on_created_by_user_id"
-    t.index ["wiki_page_id", "version_no"], name: "index_wiki_versions_on_wiki_page_id_and_version_no", unique: true
-    t.index ["wiki_page_id"], name: "index_wiki_versions_on_wiki_page_id"
-    t.check_constraint "`event_type` in (_utf8mb4'create',_utf8mb4'update',_utf8mb4'discard',_utf8mb4'restore')", name: "wiki_versions_event_type_valid"
-    t.check_constraint "`version_no` > 0", name: "wiki_versions_version_no_positive"
-  end
-
   add_foreign_key "active_storage_attachments", "active_storage_blobs", column: "blob_id"
   add_foreign_key "active_storage_variant_records", "active_storage_blobs", column: "blob_id"
   add_foreign_key "gekanator_ai_runs", "gekanator_question_suggestions"
@@ -915,12 +841,10 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_08_010000) do
   add_foreign_key "tag_implications", "tags", column: "parent_tag_id"
   add_foreign_key "tag_names", "languages", column: "language_code", primary_key: "code"
   add_foreign_key "tag_names", "scripts", column: "script_code", primary_key: "code"
-  add_foreign_key "tag_names", "tag_names", column: "canonical_id"
   add_foreign_key "tag_names", "tags"
   add_foreign_key "tag_similarities", "tags"
   add_foreign_key "tag_similarities", "tags", column: "target_tag_id"
   add_foreign_key "tag_versions", "users", column: "created_by_user_id"
-  add_foreign_key "tags", "tag_names"
   add_foreign_key "theatre_comments", "theatres"
   add_foreign_key "theatre_comments", "users"
   add_foreign_key "theatre_programmes", "posts"
@@ -945,15 +869,4 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_08_010000) do
   add_foreign_key "user_post_views", "posts"
   add_foreign_key "user_post_views", "users"
   add_foreign_key "user_theme_slots", "users"
-  add_foreign_key "wiki_pages", "tag_names"
-  add_foreign_key "wiki_pages", "users", column: "created_user_id"
-  add_foreign_key "wiki_pages", "users", column: "updated_user_id"
-  add_foreign_key "wiki_revision_lines", "wiki_lines"
-  add_foreign_key "wiki_revision_lines", "wiki_revisions"
-  add_foreign_key "wiki_revisions", "users", column: "created_user_id"
-  add_foreign_key "wiki_revisions", "wiki_pages"
-  add_foreign_key "wiki_revisions", "wiki_pages", column: "redirect_page_id"
-  add_foreign_key "wiki_revisions", "wiki_revisions", column: "base_revision_id"
-  add_foreign_key "wiki_versions", "users", column: "created_by_user_id"
-  add_foreign_key "wiki_versions", "wiki_pages"
 end

backend/db/seeds.rb

@@ -8,6 +8,11 @@
 #     MovieGenre.find_or_create_by!(name: genre_name)
 #   end
 
+ApplicationRecord.transaction do
+  Language.find_or_create_by!(code: 'ain') { _1.name = 'ain' }
+  Script.find_or_create_by!(code: 'Kana') { _1.name = 'Kana' }
+end
+
 post_url_sanitisation_rules = [
   { priority: 10,
     source_pattern: '\Ahttps?://youtu\.be/([^/?#]+)(?:[?#].*)?\z',

backend/lib/tasks/migrate_help_pages.rake

@@ -0,0 +1,51 @@
+namespace :help do
+  desc 'ヘルプ移行'
+  task migrate: :environment do
+    help_path = ENV.fetch('BTRC_HUB_HELP_PATH')
+    abort 'ヘルプ置場指定してね．' if help_path.blank?
+
+    # ファイルがすでに存在する場合は通さなぃ．
+    abort 'ファイル消してね．' if Dir.glob("#{ help_path }/*").present?
+
+    # 現状物理削除はなぃはず
+    pages = 
+        WikiPage
+        .joins(:tag_name)
+        .where(tag_names: { tag_id: nil, language_code: 'ja' })
+        .where.not("tag_names.name LIKE 'タググループ:%'")
+
+    puts "移行対象: #{pages.count} 件"
+    abort '移行対象がありません．' if pages.empty?
+
+    pages.find_each do |page|
+      puts page.body
+      puts page.title
+
+      puts 'この identifier は何にする?'
+      identifier = $stdin.gets.chomp
+      Dir.mkdir "#{ help_path }/#{ identifier }"
+      Dir.mkdir "#{ help_path }/#{ identifier }/editions"
+      Dir.mkdir "#{ help_path }/#{ identifier }/editions/ja"
+
+      last_file_name = ''
+      WikiVersion.where(wiki_page_id: page.id).order(:version_no).each do |ver|
+        last_file_name, last_file_name_no = last_file_name.split('.')
+
+        file_name = ver.created_at.strftime('%Y-%m-%d')
+        if file_name == last_file_name
+          file_name += ".#{ (last_file_name_no || 1).to_i + 1 }"
+        end
+
+        body = "# #{ ver.title.sub(/^ヘルプ:/, '') }\n\n#{ ver.body }"
+        File.write "#{ help_path }/#{ identifier }/editions/ja/#{ file_name }.mdx", body
+
+        last_file_name = file_name
+      end
+
+      article_meta = { 'identifier' => identifier,
+                       'canonical_language' => 'ja',
+                       'languages' => { 'ja' => { 'current_edition' => last_file_name } } }
+      File.write "#{ help_path }/#{ identifier }/article.yml", article_meta.to_yaml
+    end
+  end
+end

backend/spec/db/tag_description_migration_spec.rb

@@ -1,34 +0,0 @@
-require 'rails_helper'
-require_relative '../../db/migrate/20261003010000_migrate_tag_descriptions_from_wiki_pages'
-
-RSpec.describe 'Tag description migration identity' do
-  it 'preserves every revision ID and repeated body in an independent sequence' do
-    user = create_member_user!
-    tag_name = create(:tag_name, name: 'description_migration')
-    page = Wiki::Commit.create_content!(
-        tag_name:, body: 'A', created_by_user: user)
-    revisions = [page.current_revision]
-    ['A', 'B', 'B', 'A'].each do |body|
-      revisions << Wiki::Commit.content!(
-          page:, body:, created_user: user, base_revision_id: revisions.last.id)
-    end
-    tag = create(:tag, primary_tag_name: tag_name)
-    legacy_state = [page.reload.attributes, revisions.map(&:attributes)]
-    expect(page.wiki_versions.count).to eq(3)
-
-    migration = MigrateTagDescriptionsFromWikiPages.new
-    migration.suppress_messages { migration.up }
-
-    versions = TagDescriptionVersion.where(tag_id: tag.id, language_code: 'ja')
-        .order(:version_no)
-    expect(versions.pluck(:id)).to eq(revisions.map(&:id))
-    expect(versions.pluck(:version_no)).to eq([1, 2, 3, 4, 5])
-    expect(versions.pluck(:body)).to eq(['A', 'A', 'B', 'B', 'A'])
-    expect(versions.pluck(:created_by_user_id)).to eq([user.id] * 5)
-    expect(versions.pluck(:created_at)).to eq(revisions.map(&:created_at))
-    expect(TagDescription.find(page.id)).to have_attributes(
-        tag_id: tag.id, language_code: 'ja', version_no: 5, body: 'A')
-    expect([page.reload.attributes, revisions.map { |revision| revision.reload.attributes }])
-        .to eq(legacy_state)
-  end
-end

backend/spec/db/tag_group_migration_spec.rb

@@ -1,119 +0,0 @@
-require 'rails_helper'
-
-RSpec.describe 'Tag group migration identity and structure' do
-  include TagGroupRecords
-
-  let!(:user) { create_member_user! }
-
-  before { I18n.locale = :ja }
-
-  it 'preserves page and revision IDs, timestamps and repeated historical structures' do
-    tag = group_tag('洗澡鹿')
-    body = "説明文\n\n- 洗澡鹿\n- 洗澡鹿"
-    page = legacy_group('伊地知ニジカ亜種', body)
-    revisions = [page.current_revision]
-    [body, '# 空の区分', body].each do |text|
-      revisions << Wiki::Commit.legacy_content!(page:, body: text, created_user: user)
-    end
-    before_state = group_state.except(*TagGroupRecords::GROUP_TABLES)
-
-    migrate_groups
-
-    versions = group_rows('tag_group_versions', tag_group_id: page.id)
-        .sort_by { _1.fetch('version_no') }
-    expect(versions.map { _1.fetch('id') }).to eq(revisions.map(&:id))
-    expect(versions.map { _1.fetch('version_no') }).to eq([1, 2, 3, 4])
-    expect(versions.map { _1.fetch('created_at') }).to eq(revisions.map(&:created_at))
-    expect(versions.map { _1.fetch('created_by_user_id') }).to eq([user.id] * 4)
-    expect(versions.map { _1.fetch('event_type') }).to eq(['create', 'update', 'update', 'update'])
-    expect(group_version(page.id, 1).fetch('placements')).to eq(
-        group_version(page.id, 2).fetch('placements'))
-    expect(group_version(page.id, 3).fetch('placements')).to eq([
-        { 'section_name' => '空の区分', 'description' => nil, 'children' => [] }])
-    expect_group_snapshot(
-        page.id, number: 4, description: '説明文',
-        members: [{ 'tag_id' => tag.id, 'version_no' => tag.version_no }],
-        placements: [{ 'tag_id' => tag.id, 'children' => [] }] * 2)
-    expect(group_rows('tag_groups', id: page.id).sole).to include(
-        'created_at' => page.created_at, 'updated_at' => page.reload.updated_at)
-    expect(group_state.except(*TagGroupRecords::GROUP_TABLES)).to eq(before_state)
-  end
-
-  it 'migrates nested list Sections and child groups as different placement kinds' do
-    series = group_tag('ぼざろクリーチャーシリーズ')
-    deer = group_tag('洗澡鹿')
-    nijika = group_tag('伊地知ニジカ')
-    child = legacy_group('伊地知ニジカ亜種', <<~MARKDOWN)
-      - ぼざろクリーチャーシリーズ
-        - 伊地知ニジカ亜種:
-          - 洗澡鹿
-    MARKDOWN
-    parent = legacy_group('ぼざろクリーチャーシリーズのキャラクター', <<~MARKDOWN)
-      - ぼざろクリーチャーシリーズ
-        - 伊地知ニジカ
-          - タググループ:伊地知ニジカ亜種
-    MARKDOWN
-
-    migrate_groups
-
-    expect_group_snapshot(
-        child.id, number: 1,
-        members: [series, deer].map { { 'tag_id' => _1.id, 'version_no' => _1.version_no } },
-        placements: [{ 'tag_id' => series.id, 'children' => [
-            { 'section_name' => '伊地知ニジカ亜種', 'description' => nil,
-              'children' => [{ 'tag_id' => deer.id, 'children' => [] }] }] }])
-    expect_group_snapshot(
-        parent.id, number: 1,
-        members: [
-            { 'tag_id' => series.id, 'version_no' => series.version_no },
-            { 'tag_id' => nijika.id, 'version_no' => nijika.version_no },
-            { 'tag_group_id' => child.id, 'version_no' => 1 }],
-        placements: [{ 'tag_id' => series.id, 'children' => [
-            { 'tag_id' => nijika.id, 'children' => [
-                { 'tag_group_id' => child.id, 'children' => [] }] }] }])
-  end
-
-  it 'preserves heading order, group paragraphs and Section descriptions' do
-    names = ['タグ希望', 'キャラクター名希望', '楽曲情報希望', 'bot操作', 'ニジラー情報不詳']
-    tags = names.map { group_tag(_1) }
-    markdown = <<~MARKDOWN
-      全体の説明
-
-      # 要求
-      要求の説明
-
-      - タグ希望
-        - キャラクター名希望
-        - 楽曲情報希望
-
-      # 情報
-      - bot操作
-      - ニジラー情報不詳
-    MARKDOWN
-    page = legacy_group('メタタグ', markdown)
-    expect(page.current_revision.body).to eq(markdown.chomp)
-
-    migrate_groups
-
-    leaves = tags.map { { 'tag_id' => _1.id, 'children' => [] } }
-    leaves.first['children'] = leaves[1..2]
-    expect_group_snapshot(
-        page.id, number: 1, description: '全体の説明',
-        members: tags.map { { 'tag_id' => _1.id, 'version_no' => _1.version_no } },
-        placements: [
-            { 'section_name' => '要求', 'description' => '要求の説明',
-              'children' => [leaves.first] },
-            { 'section_name' => '情報', 'description' => nil,
-              'children' => leaves[3..4] }])
-  end
-
-  it 'leaves Help in the legacy domain' do
-    page = Wiki::Commit.create_legacy_content!(
-        tag_name: create(:tag_name, name: 'Help:移行対象外'),
-        body: 'Help 本文', created_by_user: user)
-    before_state = group_state
-    migrate_groups
-    expect(group_state).to eq(before_state)
-    expect(page.reload.body).to eq('Help 本文')
-  end
-end

backend/spec/db/tag_name_constraints_spec.rb

@@ -1,11 +1,17 @@
 require 'rails_helper'
 
 RSpec.describe 'TagName database invariants' do
-  def insert_name!(**attributes)
-    TagName.insert_all!([{ name: 'constraint_name', language_code: 'ja',
-                          script_code: 'Jpan', primary_flg: true,
-                          created_at: Time.current, updated_at: Time.current,
-                          **attributes }])
+  def insert_name! **attributes
+    defaults = {
+        tag_id: create(:tag, primary_tag_name: nil).id,
+        name: 'constraint_name',
+        language_code: 'ja',
+        script_code: 'Jpan',
+        primary_flg: true,
+        created_at: Time.current,
+        updated_at: Time.current }
+
+    TagName.insert_all!([defaults.merge(attributes)])
   end
 
   it 'defaults persisted names to human-confirmed provenance' do
@@ -33,4 +39,9 @@ RSpec.describe 'TagName database invariants' do
         .to raise_error(ActiveRecord::RecordNotUnique)
     expect(TagName.where(tag:, language_code: 'ja', primary_flg: true).count).to eq(1)
   end
+
+  it 'rejects a name without a tag' do
+    expect { insert_name!(tag_id: nil) }
+        .to raise_error(ActiveRecord::NotNullViolation)
+  end
 end

backend/spec/db/wiki_removal_spec.rb

@@ -0,0 +1,23 @@
+require 'rails_helper'
+
+RSpec.describe 'Schema after Wiki removal' do
+  it 'has no legacy Wiki tables or name indirection columns' do
+    connection = ApplicationRecord.connection
+    ['wiki_pages', 'wiki_revisions', 'wiki_lines', 'wiki_revision_lines', 'wiki_versions']
+        .each do |table|
+      expect(connection.table_exists?(table)).to be(false)
+    end
+    expect(connection.column_exists?(:tags, :tag_name_id)).to be(false)
+    expect(connection.column_exists?(:tag_names, :canonical_id)).to be(false)
+  end
+
+  it 'requires TagName ownership while keeping the native resources and history' do
+    connection = ApplicationRecord.connection
+    expect(TagName.columns_hash.fetch('tag_id').null).to be(false)
+    expect(connection.foreign_key_exists?(:tag_names, :tags)).to be(true)
+    ['tag_descriptions', 'tag_description_versions', 'tag_groups', 'tag_group_versions']
+        .each do |table|
+      expect(connection.table_exists?(table)).to be(true)
+    end
+  end
+end

backend/spec/factories/tag_names.rb

@@ -6,6 +6,8 @@ FactoryBot.define do
     auto_generated { false }
     sequence(:name) { |number| "tag-#{ SecureRandom.hex(4) }-#{ number }" }
 
+    association :tag, primary_tag_name: nil
+
     trait :alias do
       primary_flg { false }
     end

backend/spec/factories/tags.rb

@@ -4,7 +4,7 @@ FactoryBot.define do
       primary_name { nil }
       primary_tag_name do
         attributes = primary_name.nil? ? { } : { name: primary_name }
-        build(:tag_name, **attributes)
+        build(:tag_name, tag: nil, **attributes)
       end
     end
 
@@ -12,30 +12,19 @@ FactoryBot.define do
     post_count { 0 }
 
     after(:build) do |tag, evaluator|
+      next unless evaluator.primary_tag_name
+
       evaluator.primary_tag_name.primary_flg = true
+      evaluator.primary_tag_name.tag = tag
       tag.tag_names.target << evaluator.primary_tag_name
     end
 
-    before(:create) do |tag, evaluator|
-      evaluator.primary_tag_name.save!
-      # Compatibility write only; ownership is established through tag_id below.
-      tag.tag_name_id = evaluator.primary_tag_name.id
-    end
-
     after(:create) do |tag, evaluator|
+      next unless evaluator.primary_tag_name
+
       evaluator.primary_tag_name.update!(tag:, primary_flg: true)
 
-      Locale.where(deprecated_at: nil).order(:language_code, :created_at, :script_code).to_a
-          .uniq(&:language_code).each do |locale|
-        next if tag.tag_names.exists?(language_code: locale.language_code,
-                                      primary_flg: true)
-
-        create(:tag_name,
-            tag:, language_code: locale.language_code,
-            script_code: locale.script_code,
-            name: TagName.generate_name(locale, tag, evaluator.primary_tag_name),
-            primary_flg: true, auto_generated: true)
-      end
+      TagNameCompletion.for_tag!(tag)
     end
   end
 end

backend/spec/factories/wiki_pages.rb

@@ -1,9 +0,0 @@
-FactoryBot.define do
-  factory :wiki_page do
-    title { "TestPage" }
-    association :created_user, factory: :user
-    association :updated_user, factory: :user
-
-    body { ' ' }
-  end
-end

backend/spec/models/language_spec.rb

@@ -6,9 +6,8 @@ RSpec.describe Language, type: :model do
     expect(described_class.where(deprecated_at: nil).pluck(:code)).to eq(['ja'])
   end
 
-  it 'accepts English when multilingual support is enabled' do
-    pending '日本語以外の Language 有効化は別課題で実装する'
-    expect { described_class.create!(code: 'en', name: 'English') }
+  it 'accepts Ainu when multilingual support is enabled' do
+    expect { described_class.create!(code: 'ain', name: 'ain') }
         .to change(described_class, :count).by(1)
   end
 

backend/spec/models/locale_activation_spec.rb

@@ -0,0 +1,82 @@
+require 'rails_helper'
+
+RSpec.describe 'Locale activation', type: :model do
+  let!(:language) { Language.create!(code: 'ain', name: 'ain') }
+  let!(:script) { Script.create!(code: 'Kana', name: 'Kana') }
+  let!(:first) { create(:tag, primary_name: 'activation_first') }
+  let!(:second) { create(:tag, primary_name: 'activation_second') }
+
+  def build_locale deprecated_at: nil
+    Locale.new(code: 'ain-Kana', language_code: language.code,
+               script_code: script.code, region_code: 392, variants: '',
+               name: 'ain-Kana', deprecated_at:)
+  end
+
+  def generated_names
+    TagName.where(language_code: 'ain', primary_flg: true)
+  end
+
+  def fail_second_generation!
+    allow(TagName).to receive(:generate_name).and_call_original
+    allow(TagName).to receive(:generate_name)
+        .with(kind_of(Locale), second, second.tag_name('ja'))
+        .and_raise('backfill failed')
+  end
+
+  it 'rolls back a newly created locale and the preceding generated names' do
+    locale = build_locale
+    fail_second_generation!
+
+    expect { locale.save! }.to raise_error('backfill failed')
+
+    expect(Locale.exists?(code: 'ain-Kana')).to be(false)
+    expect(generated_names).to be_empty
+    expect(first.reload.name('ja')).to eq('activation_first')
+    expect(second.reload.name('ja')).to eq('activation_second')
+  end
+
+  it 'does not backfill while the locale is inactive' do
+    build_locale(deprecated_at: Time.current).save!
+
+    expect(generated_names).to be_empty
+  end
+
+  it 'backfills missing primary names when the locale becomes active' do
+    locale = build_locale(deprecated_at: Time.current)
+    locale.save!
+
+    locale.update!(deprecated_at: nil)
+
+    expect(generated_names.pluck(:tag_id)).to contain_exactly(first.id, second.id)
+    expect(generated_names).to all(have_attributes(
+        script_code: 'Kana', primary_flg: true, auto_generated: true))
+  end
+
+  it 'rolls back activation and all generated names when backfill fails' do
+    locale = build_locale(deprecated_at: Time.current)
+    locale.save!
+    previous_deprecated_at = locale.reload.deprecated_at
+    fail_second_generation!
+
+    expect { locale.update!(deprecated_at: nil) }.to raise_error('backfill failed')
+
+    expect(locale.reload.deprecated_at).to eq(previous_deprecated_at)
+    expect(generated_names).to be_empty
+  end
+
+  it 'preserves a human primary through deactivation and repeated activation' do
+    locale = build_locale
+    locale.save!
+    primary = generated_names.find_by!(tag: first)
+    primary.update!(name: 'human_confirmed', auto_generated: false)
+    snapshot = generated_names.order(:id).map(&:attributes)
+
+    2.times do
+      locale.update!(deprecated_at: Time.current)
+      locale.update!(deprecated_at: nil)
+    end
+
+    expect(generated_names.order(:id).map(&:attributes)).to eq(snapshot)
+    expect(primary.reload).to have_attributes(name: 'human_confirmed', auto_generated: false)
+  end
+end

backend/spec/models/locale_spec.rb

@@ -1,13 +1,13 @@
 require 'rails_helper'
 
 RSpec.describe Locale, type: :model do
-  include_context 'English locale'
+  include_context 'Ainu locale'
 
-  def create_english_locale!
-    prepare_english_reference!
-    described_class.create!(code: 'en', language_code: 'en',
-                            script_code: 'Latn', region_code: 826,
-                            variants: '', name: 'English')
+  def create_ainu_locale!
+    prepare_ainu_reference!
+    described_class.create!(code: 'ain-Kana', language_code: 'ain',
+                            script_code: 'Kana', region_code: 392,
+                            variants: '', name: 'Ainu')
   end
 
   it 'keeps the active Nipponese locale consistent with its identity tuple' do
@@ -27,7 +27,6 @@ RSpec.describe Locale, type: :model do
   end
 
   it 'generates a primary name for every existing tag using the name generator' do
-    pending '日本語以外の Locale 有効化は別課題で実装する'
     first = create(:tag, primary_name: 'first_existing_tag')
     second = create(:tag, primary_name: 'second_existing_tag')
     allow(TagName).to receive(:generate_name).and_call_original
@@ -35,63 +34,60 @@ RSpec.describe Locale, type: :model do
         .with(kind_of(described_class), first, primary_tag_name_for(first, 'ja'))
         .and_return('name_from_generator')
 
-    locale = create_english_locale!
+    locale = create_ainu_locale!
 
     expect(TagName).to have_received(:generate_name)
         .with(locale, first, primary_tag_name_for(first, 'ja'))
     expect(TagName).to have_received(:generate_name)
         .with(locale, second, primary_tag_name_for(second, 'ja'))
-    expect(first.tag_names.find_by!(language_code: 'en', primary_flg: true))
+    expect(first.tag_names.find_by!(language_code: 'ain', primary_flg: true))
         .to have_attributes(name: 'name_from_generator', tag_id: first.id,
-                            language_code: 'en', script_code: 'Latn',
+                            language_code: 'ain', script_code: 'Kana',
                             primary_flg: true, auto_generated: true)
-    expect(second.tag_names.find_by!(language_code: 'en', primary_flg: true))
-        .to have_attributes(tag_id: second.id, language_code: 'en',
-                            script_code: 'Latn', primary_flg: true,
+    expect(second.tag_names.find_by!(language_code: 'ain', primary_flg: true))
+        .to have_attributes(tag_id: second.id, language_code: 'ain',
+                            script_code: 'Kana', primary_flg: true,
                             auto_generated: true)
-    expect(TagName.where(language_code: 'en', primary_flg: true,
+    expect(TagName.where(language_code: 'ain', primary_flg: true,
                          tag_id: [first.id, second.id]).count).to eq(2)
   end
 
   it 'does not duplicate an existing primary name in the new language' do
-    pending '日本語以外の Locale 有効化は別課題で実装する'
-    prepare_english_reference!
+    prepare_ainu_reference!
     tag = create(:tag, primary_name: 'already_named')
-    existing = create(:tag_name, name: 'existing_english', tag:,
-                                 language_code: 'en', script_code: 'Latn')
+    existing = create(:tag_name, name: 'existing_ainu', tag:,
+                                 language_code: 'ain', script_code: 'Kana')
 
-    create_english_locale!
+    create_ainu_locale!
 
-    expect(TagName.where(tag_id: tag.id, language_code: 'en', primary_flg: true))
+    expect(TagName.where(tag_id: tag.id, language_code: 'ain', primary_flg: true))
         .to contain_exactly(existing)
     expect(existing.reload).to have_attributes(
-        tag_id: tag.id, language_code: 'en', script_code: 'Latn',
+        tag_id: tag.id, language_code: 'ain', script_code: 'Kana',
         primary_flg: true, auto_generated: false)
   end
 
   it 'creates a primary name when the language has only an alias' do
-    pending '日本語以外の Locale 有効化は別課題で実装する'
-    prepare_english_reference!
+    prepare_ainu_reference!
     tag = create(:tag, primary_name: 'alias_only_tag')
     alias_name = create(:tag_name, :alias, name: 'alias_en',
                                           tag:,
-                                          language_code: 'en', script_code: 'Latn')
+                                          language_code: 'ain', script_code: 'Kana')
 
-    create_english_locale!
+    create_ainu_locale!
 
     expect(alias_name.reload).to have_attributes(
         tag_id: tag.id,
-        language_code: 'en', script_code: 'Latn', primary_flg: false)
-    generated = TagName.find_by!(tag_id: tag.id, language_code: 'en', primary_flg: true)
-    expect(generated).to have_attributes(tag_id: tag.id, language_code: 'en',
-                                         script_code: 'Latn', primary_flg: true,
+        language_code: 'ain', script_code: 'Kana', primary_flg: false)
+    generated = TagName.find_by!(tag_id: tag.id, language_code: 'ain', primary_flg: true)
+    expect(generated).to have_attributes(tag_id: tag.id, language_code: 'ain',
+                                         script_code: 'Kana', primary_flg: true,
                                          auto_generated: true)
-    expect(TagName.where(tag_id: tag.id, language_code: 'en', primary_flg: true).count).to eq(1)
+    expect(TagName.where(tag_id: tag.id, language_code: 'ain', primary_flg: true).count).to eq(1)
   end
 
   it 'rolls back the locale and all generated names when backfill fails' do
-    pending '日本語以外の Locale 有効化は別課題で実装する'
-    prepare_english_reference!
+    prepare_ainu_reference!
     first = create(:tag, primary_name: 'atomic_first')
     second = create(:tag, primary_name: 'atomic_second')
     allow(TagName).to receive(:generate_name).and_call_original
@@ -99,31 +95,27 @@ RSpec.describe Locale, type: :model do
         .with(kind_of(described_class), second, primary_tag_name_for(second, 'ja'))
         .and_raise('backfill failed')
 
-    expect { create_english_locale! }.to raise_error('backfill failed')
+    expect { create_ainu_locale! }.to raise_error('backfill failed')
 
-    expect(described_class.exists?(code: 'en')).to be(false)
-    expect(TagName.where(language_code: 'en', tag_id: [first.id, second.id])).to be_empty
+    expect(described_class.exists?(code: 'ain-Kana')).to be(false)
+    expect(TagName.where(language_code: 'ain', tag_id: [first.id, second.id])).to be_empty
   end
 
-  it 'accepts a stable locale code outside the historical enum values' do
-    pending '日本語以外の Locale 有効化は別課題で実装する'
-    prepare_english_reference!
+  it 'rejects a private locale code outside the supported locale set' do
+    prepare_ainu_reference!
 
-    locale = described_class.create!(
-        code: 'en-x-rspec', language_code: 'en',
-        script_code: 'Latn', region_code: 826,
-        variants: 'x-rspec', name: 'English')
-
-    expect(locale.reload).to have_attributes(
-        code: 'en-x-rspec', language_code: 'en', script_code: 'Latn',
-        region_code: 826, variants: 'x-rspec')
+    expect {
+      described_class.create!(
+          code: 'ain-Kana-x-rspec', language_code: 'ain',
+          script_code: 'Kana', region_code: 392,
+          variants: 'x-rspec', name: 'Ainu')
+    }.to raise_error(ArgumentError)
   end
 
-  it 'registers the future British English locale tuple' do
-    pending '日本語以外の Locale 有効化は別課題で実装する'
+  it 'registers the supported Ainu locale tuple' do
 
-    expect(locale).to have_attributes(code: 'en', language_code: 'en',
-                                    script_code: 'Latn', region_code: 826,
+    expect(locale).to have_attributes(code: 'ain-Kana', language_code: 'ain',
+                                    script_code: 'Kana', region_code: 392,
                                     variants: '')
   end
 end

backend/spec/models/script_spec.rb

@@ -1,7 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe Script, type: :model do
-  include_context 'English locale'
+  include_context 'Ainu locale'
 
   it 'selects locales by script code, not language code' do
     expect(described_class.find('Jpan').locales).to contain_exactly(Locale.nipponese)
@@ -25,11 +25,10 @@ RSpec.describe Script, type: :model do
     }
   end
 
-  it 'selects Latin locales when multilingual support is enabled' do
-    pending '日本語以外の Locale 有効化は別課題で実装する'
+  it 'selects Kana locales when multilingual support is enabled' do
     locale
 
-    expect(described_class.find('Latn').locales).to contain_exactly(locale)
+    expect(described_class.find('Kana').locales).to contain_exactly(locale)
     expect(described_class.find('Jpan').locales).not_to include(locale)
   end
 end

backend/spec/models/shared_tag_ids_spec.rb

@@ -0,0 +1,37 @@
+require 'rails_helper'
+
+RSpec.describe 'Shared Tag and ExternalTag IDs', type: :model do
+  it 'allocates distinct increasing IDs across the two tables' do
+    tag = create(:tag)
+    external = create(:external_tag)
+    next_tag = create(:tag)
+
+    expect(external.id).to be > tag.id
+    expect(next_tag.id).to be > external.id
+  end
+
+  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!
+    external.destroy!
+
+    expect(create(:tag).id).to be > external.id
+    expect(create(:external_tag).id).to be > external.id
+  end
+
+  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
+
+    expect(create(:tag).id).to be > tag.id
+    expect(tag.reload.attributes).to eq(before_tag)
+    expect(external.reload.attributes).to eq(before_external)
+  end
+end

backend/spec/models/tag_group_spec.rb

@@ -0,0 +1,48 @@
+require 'rails_helper'
+
+RSpec.describe TagGroup, type: :model do
+  let(:actor) { create_member_user! }
+
+  def create_group name:, members: [], placements: []
+    TagGroupOperation.create!(
+        Locale.nipponese, name:, description: nil, members:, placements:, actor:)
+  end
+
+  it 'retains version IDs and snapshots after destroying an empty group' do
+    group = create_group(name: 'history owner')
+    versions = group.versions.order(:version_no).map(&:attributes)
+
+    expect { group.destroy! }.to change(described_class, :count).by(-1)
+        .and change(TagGroupVersion, :count).by(0)
+
+    expect(TagGroupVersion.where(tag_group_id: group.id).order(:version_no).map(&:attributes))
+        .to eq(versions)
+    expect(TagGroupRepr.historical(
+        Locale.nipponese, TagGroupVersion.find(versions.first.fetch('id'))))
+        .to include('id' => group.id, 'name' => 'history owner', 'members' => [])
+  end
+
+  it 'destroys a group with nested placements and child membership, retaining history' do
+    child = create_group(name: 'child group')
+
+    parent = create_group(
+        name: 'parent group',
+        members: [{ 'tag_group_id' => child.id }],
+        placements: [{ 'section_name' => 'section', 'description' => nil,
+                       'children' => [{ 'tag_group_id' => child.id, 'children' => [] }] }])
+
+    versions = parent.versions.order(:version_no).map(&:attributes)
+
+    expect { parent.destroy! }
+        .to change(TagGroup, :count).by(-1)
+        .and change(TagGroupVersion, :count).by(0)
+
+    expect(TagGroupVersion.where(tag_group_id: parent.id)
+        .order(:version_no).map(&:attributes)).to eq(versions)
+
+    expect(child.reload).to be_persisted
+    expect(TagGroupPlacement.where(tag_group_id: parent.id)).to be_empty
+    expect(TagGroupTag.where(tag_group_id: parent.id)).to be_empty
+    expect(TagGroupGroup.where(tag_group_id: parent.id)).to be_empty
+  end
+end

backend/spec/models/tag_name_sanitisation_rule_spec.rb

@@ -34,39 +34,97 @@ RSpec.describe TagNameSanitisationRule, type: :model do
       described_class.create!(priority: 10, source_pattern: 'foo_', replacement: 'foo')
     end
 
+    [:primary, :alias].each do |source_kind|
+      it "keeps the primary identity when a #{ source_kind } collides within its Tag" do
+        tag = create(:tag, primary_name: source_kind == :primary ? 'temporary' : 'foobar')
+        primary = tag.tag_name('ja')
+        alias_name = create(:tag_name, :alias, tag:,
+                             name: source_kind == :primary ? 'foobar' : 'temporary_alias')
+        source = source_kind == :primary ? primary : alias_name
+        source.update_columns(name: 'foo_bar')
+
+        expect { described_class.apply! }.to change(TagName, :count).by(-1)
+            .and change(Tag, :count).by(0)
+
+        expect(primary.reload).to have_attributes(
+            name: 'foobar', primary_flg: true, tag_id: tag.id)
+        expect(TagName.exists?(alias_name.id)).to be(false)
+        expect(TagName.where(tag:, language_code: 'ja', primary_flg: true))
+            .to contain_exactly(primary)
+        expect(tag.tag_versions.order(:version_no).last.names.fetch('ja'))
+            .to include('name' => 'foobar', 'aliases' => [])
+      end
+    end
+
+    it 'deduplicates colliding aliases without changing the primary name' do
+      tag = create(:tag, primary_name: 'primary')
+      primary = tag.tag_name('ja')
+      kept = create(:tag_name, :alias, tag:, name: 'foobar')
+      removed = create(:tag_name, :alias, tag:, name: 'temporary_alias')
+      removed.update_columns(name: 'foo_bar')
+
+      described_class.apply!
+
+      expect(primary.reload).to have_attributes(name: 'primary', primary_flg: true)
+      expect(kept.reload.tag_id).to eq(tag.id)
+      expect(TagName.exists?(removed.id)).to be(false)
+      expect(tag.tag_versions.order(:version_no).last.names.fetch('ja').fetch('aliases'))
+          .to eq([{ 'name' => 'foobar', 'script_code' => 'Jpan' }])
+    end
+
+    it 'rolls back a collision merge when the source owns a description' do
+      user = create_member_user!
+      target = create(:tag, primary_name: 'foobar')
+      source = create(:tag, primary_name: 'temporary')
+      TagDescriptionOperation.create!(
+          Locale.nipponese, tag: source, body: 'retained', created_by_user: user)
+      source.tag_name('ja').update_columns(name: 'foo_bar')
+      post = create(:post)
+      PostTag.create!(post:, tag: source)
+      models = [Tag, TagName, TagVersion, TagDescription, TagDescriptionVersion, PostTag]
+      snapshots = models.map { |model| model.order(*Array(model.primary_key)).map(&:attributes) }
+
+      expect { described_class.apply! }.to raise_error(ActiveRecord::RecordInvalid)
+
+      after_state = models.map do |model|
+        model.order(*Array(model.primary_key)).map(&:attributes)
+      end
+      expect(after_state).to eq(snapshots)
+      expect(post.reload.tags).to contain_exactly(source)
+      expect(target.reload.name('ja')).to eq('foobar')
+    end
+
     context 'when only another language has the sanitised name' do
-      include_context 'English locale'
+      include_context 'Ainu locale'
 
       it 'keeps both names when sanitisation produces a cross-language match' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
         locale
         nipponese = create(:tag_name, name: 'foobar')
-        english = create(:tag_name, name: 'temporary',
-                                   language_code: 'en', script_code: 'Latn')
-        english.update_columns(name: 'foo_bar')
+        ainu = create(:tag_name, name: 'temporary',
+                                   language_code: 'ain', script_code: 'Kana')
+        ainu.update_columns(name: 'foo_bar')
 
         expect { described_class.apply! }.not_to change(TagName, :count)
 
-        expect(english.reload).to have_attributes(name: 'foobar', language_code: 'en')
+        expect(ainu.reload).to have_attributes(name: 'foobar', language_code: 'ain')
         expect(nipponese.reload).to have_attributes(name: 'foobar', language_code: 'ja')
       end
 
       it 'renames without merging tags or deleting either language identity' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
         locale
         nipponese = create(:tag, primary_name: 'foobar')
-        english_name = create(:tag_name, name: 'temporary',
-                                        language_code: 'en', script_code: 'Latn')
-        english = create(:tag, primary_tag_name: english_name)
-        english_name.update_columns(name: 'foo_bar')
+        ainu_name = create(:tag_name, name: 'temporary',
+                                        language_code: 'ain', script_code: 'Kana')
+        ainu = create(:tag, primary_tag_name: ainu_name)
+        ainu_name.update_columns(name: 'foo_bar')
 
         described_class.apply!
 
-        expect(english_name.reload).to have_attributes(
-            name: 'foobar', language_code: 'en', tag_id: english.id)
+        expect(ainu_name.reload).to have_attributes(
+            name: 'foobar', language_code: 'ain', tag_id: ainu.id)
         expect(primary_tag_name_for(nipponese.reload, 'ja')).to have_attributes(
             name: 'foobar', language_code: 'ja', tag_id: nipponese.id)
-        expect(primary_tag_name_for(english.reload, 'en')).to eq(english_name)
+        expect(primary_tag_name_for(ainu.reload, 'ain')).to eq(ainu_name)
       end
     end
 
@@ -98,25 +156,6 @@ RSpec.describe TagNameSanitisationRule, type: :model do
       end
     end
 
-    context 'when the source tag_name has a tag and the existing one has no tag' do
-      let!(:existing) { create(:tag_name, name: 'foobar') }
-      let!(:source_tag) { create(:tag, primary_name: 'tmp', category: :general) }
-      let!(:source_tag_name_id) { primary_tag_name_for(source_tag, 'ja').id }
-
-      before do
-        primary_tag_name_for(source_tag, 'ja').update_columns(
-            name: 'foo_bar', updated_at: Time.current)
-      end
-
-      it 'moves the tag to the existing tag_name' do
-        described_class.apply!
-        expect(existing.reload).to have_attributes(
-            tag_id: source_tag.id, language_code: 'ja', primary_flg: true)
-        expect(primary_tag_name_for(source_tag, 'ja')).to eq(existing)
-        expect(primary_tag_name_for(source_tag.reload, 'ja')).to eq(existing)
-        expect(TagName.unscoped.exists?(source_tag_name_id)).to be(false)
-      end
-    end
 
     context 'when the sanitised name is an alias of an existing tag' do
       let!(:existing_tag) { create(:tag) }

backend/spec/models/tag_name_spec.rb

@@ -1,17 +1,16 @@
 require 'rails_helper'
 
 RSpec.describe TagName, type: :model do
-  include_context 'English locale'
+  include_context 'Ainu locale'
 
   it 'allows the same name in different languages' do
-    pending '日本語以外の Locale 有効化は別課題で実装する'
     locale
     create(:tag_name, name: 'shared_name')
-    english = build(:tag_name, name: 'shared_name',
-                              language_code: 'en', script_code: 'Latn')
+    ainu = build(:tag_name, name: 'shared_name',
+                              language_code: 'ain', script_code: 'Kana')
 
-    expect(english).to be_valid
-    expect { english.save! }.to change(described_class, :count).by(1)
+    expect(ainu).to be_valid
+    expect { ainu.save! }.to change(described_class, :count).by(1)
   end
 
   it 'rejects a duplicate name within the same language' do
@@ -22,16 +21,23 @@ RSpec.describe TagName, type: :model do
     expect(duplicate.errors.of_kind?(:name, :taken)).to be(true)
   end
 
-  it 'creates Nipponese factory names without requiring a tag' do
+  it 'creates Nipponese factory names with an owning tag' do
     name = create(:tag_name)
 
     expect(name.reload).to have_attributes(
         language_code: 'ja', script_code: 'Jpan', primary_flg: true,
-        auto_generated: false, tag_id: nil)
+        auto_generated: false, tag_id: name.tag.id)
+  end
+
+  it 'rejects an ownerless name at model and database boundaries' do
+    name = build(:tag_name, tag: nil)
+    expect(name).to be_invalid
+    expect { name.save!(validate: false) }.to raise_error(ActiveRecord::NotNullViolation)
   end
 
   it 'defaults ordinary persisted human names to confirmed provenance' do
-    name = described_class.create!(name: 'ordinary_human_name', language_code: 'ja',
+    name = described_class.create!(tag: create(:tag, primary_tag_name: nil),
+                                   name: 'ordinary_human_name', language_code: 'ja',
                                    script_code: 'Jpan', primary_flg: true)
 
     expect(name.reload.auto_generated).to be(false)
@@ -46,7 +52,7 @@ RSpec.describe TagName, type: :model do
     expect(name.tag).to eq(tag)
     expect(described_class.find_by!(tag_id: tag.id, language_code: 'ja', primary_flg: true))
         .to eq(name)
-    expect(tag.reload.tag_name_id).to eq(name.id)
+    expect(tag.reload.tag_name('ja')&.id).to eq(name.id)
   end
 
   it 'creates a complete ordinary tag factory under the active Nipponese language' do
@@ -60,11 +66,10 @@ RSpec.describe TagName, type: :model do
   end
 
   it 'completes an ordinary tag factory under future active languages' do
-    pending '日本語以外の Locale 有効化は別課題で実装する'
     locale
     tag = create(:tag, primary_name: 'future_factory')
 
-    expect(TagName.where(tag:, language_code: 'en', primary_flg: true))
+    expect(TagName.where(tag:, language_code: 'ain', primary_flg: true))
         .to contain_exactly(have_attributes(auto_generated: true))
   end
 
@@ -96,62 +101,55 @@ RSpec.describe TagName, type: :model do
   end
 
   describe '.canonicalise' do
-    it 'leaves detached aliases unchanged' do
-      create(:tag_name, :alias, name: 'detached_alias')
 
-      expect(described_class.canonicalise(Locale.nipponese, ['detached_alias']))
-          .to eq(['detached_alias'])
-    end
 
-    it 'does not resolve a detached alias through another detached primary' do
-      create(:tag_name, :alias, name: 'detached_alias')
-      create(:tag_name, name: 'unrelated_detached_primary')
+    it 'resolves an alias to its owning primary name' do
+      tag = create(:tag, primary_name: 'canonical')
+      create(:tag_name, :alias, tag:, name: 'alias')
 
-      expect(described_class.canonicalise(Locale.nipponese, ['detached_alias']))
-          .to eq(['detached_alias'])
+      expect(described_class.canonicalise(Locale.nipponese, ['alias', 'unknown']))
+          .to eq(['canonical', 'unknown'])
     end
 
     it 'resolves the primary name of the alias language on the same tag' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
       locale
       tag = create(:tag, primary_name: '日本語正本')
-      english_primary = primary_tag_name_for(tag, 'en')
-      english_primary.update!(name: 'english_primary', auto_generated: false)
-      english_alias = create(:tag_name, :alias, tag:, name: 'english_alias',
-                                                 language_code: 'en', script_code: 'Latn')
-      representative_id = tag.tag_name_id
+      ainu_primary = primary_tag_name_for(tag, 'ain')
+      ainu_primary.update!(name: 'ainu_primary', auto_generated: false)
+      ainu_alias = create(:tag_name, :alias, tag:, name: 'ainu_alias',
+                                                 language_code: 'ain', script_code: 'Kana')
+      representative_id = tag.tag_name('ja')&.id
 
-      primary = described_class.find_by!(tag_id: english_alias.tag_id,
-                                         language_code: english_alias.language_code,
+      primary = described_class.find_by!(tag_id: ainu_alias.tag_id,
+                                         language_code: ainu_alias.language_code,
                                          primary_flg: true)
 
-      expect(primary).to eq(english_primary)
-      expect(described_class.canonicalise(locale, [english_alias.name]))
-          .to eq([english_primary.name])
-      expect(tag.reload.tag_name_id).to eq(representative_id)
+      expect(primary).to eq(ainu_primary)
+      expect(described_class.canonicalise(locale, [ainu_alias.name]))
+          .to eq([ainu_primary.name])
+      expect(tag.reload.tag_name('ja')&.id).to eq(representative_id)
     end
 
     it 'resolves only aliases in the requested language' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
       locale
       nipponese = create(:tag, primary_name: 'nipponese_canonical')
-      english_name = create(:tag_name, name: 'english_canonical',
-                                      language_code: 'en', script_code: 'Latn')
-      english = create(:tag, primary_tag_name: english_name)
+      ainu_name = create(:tag_name, name: 'ainu_canonical',
+                                      language_code: 'ain', script_code: 'Kana')
+      ainu = create(:tag, primary_tag_name: ainu_name)
       nipponese_alias = create(:tag_name, :alias, name: 'shared_alias',
                                                   tag: nipponese)
-      english_alias = create(:tag_name, :alias, name: 'shared_alias',
-                                                tag: english,
-                                                language_code: 'en', script_code: 'Latn')
+      ainu_alias = create(:tag_name, :alias, name: 'shared_alias',
+                                                tag: ainu,
+                                                language_code: 'ain', script_code: 'Kana')
 
       expect(nipponese_alias.reload).to have_attributes(
           tag_id: nipponese.id,
           primary_flg: false, language_code: 'ja')
-      expect(english_alias.reload).to have_attributes(
-          tag_id: english.id,
-          primary_flg: false, language_code: 'en')
+      expect(ainu_alias.reload).to have_attributes(
+          tag_id: ainu.id,
+          primary_flg: false, language_code: 'ain')
       expect(described_class.canonicalise(locale, ['shared_alias']))
-          .to eq(['english_canonical'])
+          .to eq(['ainu_canonical'])
       expect(described_class.canonicalise(Locale.nipponese, ['shared_alias']))
           .to eq(['nipponese_canonical'])
     end

backend/spec/models/tag_repr_spec.rb

@@ -0,0 +1,50 @@
+require 'rails_helper'
+
+RSpec.describe TagRepr do
+  let(:tag) { create(:tag) }
+
+  def description_for record
+    TagDescription.create!(tag: record, language_code: 'ja', body: '', version_no: 1)
+  end
+
+  it 'keeps has_wiki boolean for the selected language in base and inline' do
+    description_for(tag)
+    [:base, :inline].each do |method|
+      expect(described_class.public_send(method, tag).as_json.fetch('has_wiki')).to be(true)
+      expect(described_class.public_send(method, tag, language_code: 'en')
+          .as_json.fetch('has_wiki')).to be(false)
+    end
+  end
+
+  it 'uses the same language for a tag and its parents' do
+    parent = create(:tag)
+    description_for(tag)
+    description_for(parent)
+    TagImplication.create!(tag:, parent_tag: parent)
+    ['ja', 'en'].each do |language_code|
+      row = described_class.base(tag, language_code:).as_json
+      expected = language_code == 'ja'
+      expect(row.fetch('has_wiki')).to be(expected)
+      expect(row.fetch('parents').sole.fetch('has_wiki')).to be(expected)
+    end
+  end
+
+  it 'preloads existence checks for many tags and their parents without Wiki reads' do
+    parent = create(:tag)
+    description_for(parent)
+    records = Array.new(3) do
+      create(:tag).tap { TagImplication.create!(tag: _1, parent_tag: parent) }
+    end
+    description_for(records.first)
+    queries = []
+    subscriber = ->(*args) { queries << args.last.fetch(:sql) }
+    rows = nil
+    ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') do
+      rows = described_class.many(records).as_json
+    end
+    expect(rows.map { _1.fetch('has_wiki') }).to eq([true, false, false])
+    expect(rows.map { _1.fetch('parents').sole.fetch('has_wiki') }).to eq([true] * 3)
+    expect(queries.grep(/\bSELECT\b.*\btag_descriptions\b/im).size).to be <= 2
+    expect(queries.grep(/\bwiki_(pages|revisions|versions)\b/i)).to be_empty
+  end
+end

backend/spec/models/tag_spec.rb

@@ -1,6 +1,42 @@
 require 'rails_helper'
 
 RSpec.describe Tag, type: :model do
+  include WikiRecords
+  describe '#has_description?' do
+    let(:tag) { create(:tag) }
+
+    it 'checks the requested language and treats an empty description as present' do
+      TagDescription.create!(tag:, language_code: 'ja', body: '', version_no: 1)
+      expect(tag.has_description?(language_code: 'ja')).to be(true)
+      expect(tag.has_description?(language_code: 'ain')).to be(false)
+    end
+
+    it 'returns false without a description' do
+      expect(tag.has_description?(language_code: 'ja')).to be(false)
+    end
+
+
+    it 'reuses preloaded descriptions without reading Wiki or querying again' do
+      TagDescription.create!(tag:, language_code: 'ja', body: '', version_no: 1)
+      loaded = Tag.includes(:tag_descriptions).find(tag.id)
+      queries = []
+      subscriber = ->(*args) { queries << args.last.fetch(:sql) }
+      ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') do
+        expect(loaded.has_description?(language_code: 'ja')).to be(true)
+        expect(loaded.has_description?(language_code: 'ain')).to be(false)
+      end
+      expect(queries).to be_empty
+    end
+
+    it 'keeps language selection generic without enabling another Language record' do
+      tag.association(:tag_descriptions).target = [
+          TagDescription.new(tag:, language_code: 'ain', body: '', version_no: 1)]
+      tag.association(:tag_descriptions).loaded!
+      expect(tag.has_description?(language_code: 'ain')).to be(true)
+      expect(tag.has_description?(language_code: 'ja')).to be(false)
+    end
+  end
+
   describe 'external tag separation' do
     ['nico:reserved', 'NiCo:reserved'].each do |name|
       it "rejects the reserved prefix #{ name } for internal tags" do
@@ -25,33 +61,32 @@ RSpec.describe Tag, type: :model do
   end
 
   describe '.normalise_tags!' do
-    include_context 'English locale'
+    include_context 'Ainu locale'
 
     it 'canonicalises aliases in the supplied language only' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
-      prepare_english_reference!
+      prepare_ainu_reference!
       nipponese = create(:tag, primary_name: 'nipponese_canonical')
-      english_name = create(:tag_name, name: 'english_canonical',
-                                      language_code: 'en', script_code: 'Latn')
-      english = create(:tag, primary_tag_name: english_name)
-      primary_tag_name_for(english, 'ja').update!(
-          name: 'english_in_nipponese', auto_generated: false)
-      english_locale = locale
+      ainu_name = create(:tag_name, name: 'ainu_canonical',
+                                      language_code: 'ain', script_code: 'Kana')
+      ainu = create(:tag, primary_tag_name: ainu_name)
+      primary_tag_name_for(ainu, 'ja').update!(
+          name: 'ainu_in_nipponese', auto_generated: false)
+      ainu_locale = locale
       nipponese_alias = create(:tag_name, :alias, name: 'shared_alias',
                                                   tag: nipponese)
-      english_alias = create(:tag_name, :alias, name: 'shared_alias',
-                                                tag: english,
-                                                language_code: 'en', script_code: 'Latn')
+      ainu_alias = create(:tag_name, :alias, name: 'shared_alias',
+                                                tag: ainu,
+                                                language_code: 'ain', script_code: 'Kana')
 
       expect(nipponese_alias.reload).to have_attributes(
           tag_id: nipponese.id,
           primary_flg: false, language_code: 'ja')
-      expect(english_alias.reload).to have_attributes(
-          tag_id: english.id,
-          primary_flg: false, language_code: 'en')
+      expect(ainu_alias.reload).to have_attributes(
+          tag_id: ainu.id,
+          primary_flg: false, language_code: 'ain')
       expect(described_class.normalise_tags!(
-          english_locale, ['shared_alias'],
-          with_tagme: false, with_no_deerjikist: false)).to eq([english])
+          ainu_locale, ['shared_alias'],
+          with_tagme: false, with_no_deerjikist: false)).to eq([ainu])
       expect(described_class.normalise_tags!(
           Locale.nipponese, ['shared_alias'],
           with_tagme: false, with_no_deerjikist: false)).to eq([nipponese])
@@ -217,160 +252,120 @@ RSpec.describe Tag, type: :model do
 
   describe '.find_or_create_by_tag_name!' do
     context 'with an explicit locale' do
-      include_context 'English locale'
+      include_context 'Ainu locale'
 
       it 'creates the representative name with locale attributes and ownership' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
         locale
         tag = described_class.find_or_create_by_tag_name!(
-            locale, 'english_name', category: :character)
+            locale, 'ainu_name', category: :character)
 
-        expect(primary_tag_name_for(tag, 'en')).to have_attributes(
-            language_code: 'en', script_code: 'Latn',
+        expect(primary_tag_name_for(tag, 'ain')).to have_attributes(
+            language_code: 'ain', script_code: 'Kana',
             primary_flg: true, tag_id: tag.id)
         expect(tag.category).to eq('character')
       end
 
-      it 'uses the English primary as the source for a generated Nipponese name' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
+      it 'uses a Japanese fallback for an Ainu-origin tag without reverse transcription' do
         locale
-        allow(TagName).to receive(:generate_name).and_return('generated_nipponese')
+        allow(TagName).to receive(:generate_name).and_call_original
 
         tag = described_class.find_or_create_by_tag_name!(
-            locale, 'english_origin', category: :general)
+            locale, 'ainu_origin', category: :general)
 
-        expect(TagName.where(tag:, language_code: 'en', primary_flg: true))
+        expect(TagName.where(tag:, language_code: 'ain', primary_flg: true))
             .to contain_exactly(have_attributes(
-                name: 'english_origin', auto_generated: false))
+                name: 'ainu_origin', auto_generated: false))
         expect(TagName.where(tag:, language_code: 'ja', primary_flg: true))
             .to contain_exactly(have_attributes(
-                name: 'generated_nipponese', auto_generated: true))
-        source_tag_name = TagName.find_by!(tag:, language_code: 'en', primary_flg: true)
+                name: "Tag_##{ tag.id }", auto_generated: true))
         expect(TagName).to have_received(:generate_name)
-            .with(Locale.nipponese, tag, source_tag_name)
+            .with(Locale.nipponese, tag, nil)
       end
 
       it 'gives a new tag one primary name for every active language' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
         locale
         tag = described_class.find_or_create_by_tag_name!(
             Locale.nipponese, 'new_multilingual_tag', category: :general)
 
         expect(TagName.where(tag:, language_code: 'ja', primary_flg: true).count).to eq(1)
-        expect(TagName.where(tag:, language_code: 'en', primary_flg: true).count).to eq(1)
+        expect(TagName.where(tag:, language_code: 'ain', primary_flg: true).count).to eq(1)
       end
 
-      it 'creates one primary per language when multiple locales use English' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
+      it 'creates one primary per language when multiple locales use Ainu' do
         locale
         described_class.find_or_create_by_tag_name!(
-            locale, 'before_second_english_locale', category: :general)
-        Locale.create!(code: 'en-x-rspec', language_code: 'en',
-                       script_code: 'Latn', region_code: 826,
-                       variants: 'x-rspec', name: 'English')
+            locale, 'before_second_ainu_locale', category: :general)
 
         tag = described_class.find_or_create_by_tag_name!(
-            locale, 'one_english_primary', category: :general)
+            locale, 'one_ainu_primary', category: :general)
+        TagNameCompletion.for_tag!(tag, locales: [locale, locale.dup, Locale.nipponese])
 
-        expect(TagName.where(tag:, language_code: 'en', primary_flg: true).count).to eq(1)
+        expect(TagName.where(tag:, language_code: 'ain', primary_flg: true).count).to eq(1)
         expect(TagName.where(tag:, language_code: 'ja', primary_flg: true).count).to eq(1)
       end
 
       it 'rolls back a new tag and requested name if name generation fails' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
         locale
         original_tag_count = described_class.count
         allow(TagName).to receive(:generate_name).and_raise('generation failed')
 
         expect {
           described_class.find_or_create_by_tag_name!(
-              locale, 'atomic_english_name', category: :general)
+              locale, 'atomic_ainu_name', category: :general)
         }.to raise_error('generation failed')
 
         expect(described_class.count).to eq(original_tag_count)
-        expect(TagName.where(language_code: 'en', name: 'atomic_english_name')).to be_empty
+        expect(TagName.where(language_code: 'ain', name: 'atomic_ainu_name')).to be_empty
         expect(described_class.joins(:tag_names)
-            .where(tag_names: { name: 'atomic_english_name' })).to be_empty
+            .where(tag_names: { name: 'atomic_ainu_name' })).to be_empty
       end
 
-      it 'keeps a detached requested name detached if generation fails' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
-        locale
-        detached = create(:tag_name, :alias, name: 'atomic_detached',
-                                           language_code: 'en', script_code: 'Latn')
-        original_tag_count = described_class.count
-        allow(TagName).to receive(:generate_name).and_raise('generation failed')
 
-        expect {
-          described_class.find_or_create_by_tag_name!(
-              locale, detached.name, category: :general)
-        }.to raise_error('generation failed')
-
-        expect(described_class.count).to eq(original_tag_count)
-        expect(detached.reload).to have_attributes(tag_id: nil, primary_flg: false)
-      end
-
-      it 'promotes a detached alias into the requested primary name' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
-        locale
-        detached = create(:tag_name, :alias, name: 'detached_english',
-                                           language_code: 'en', script_code: 'Latn')
-
-        tag = described_class.find_or_create_by_tag_name!(
-            locale, detached.name, category: :general)
-
-        expect(detached.reload).to have_attributes(
-            tag_id: tag.id, primary_flg: true, canonical_id: nil,
-            auto_generated: false)
-        expect(TagName.where(tag:, language_code: 'en', primary_flg: true))
-            .to contain_exactly(detached)
-      end
 
       it 'creates separate tag identities for the same name in different languages' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
         locale
         nipponese = described_class.find_or_create_by_tag_name!(
             Locale.nipponese, 'same_name', category: :general)
-        english = described_class.find_or_create_by_tag_name!(
+        primary_tag_name_for(nipponese, 'ain').update!(
+            name: 'other_ainu_name', auto_generated: false)
+        ainu = described_class.find_or_create_by_tag_name!(
             locale, 'same_name', category: :character)
 
-        expect(english).not_to eq(nipponese)
-        expect(primary_tag_name_for(english, 'en')).to have_attributes(
-            name: 'same_name', tag_id: english.id, language_code: 'en', primary_flg: true)
+        expect(ainu).not_to eq(nipponese)
+        expect(primary_tag_name_for(ainu, 'ain')).to have_attributes(
+            name: 'same_name', tag_id: ainu.id, language_code: 'ain', primary_flg: true)
         expect(primary_tag_name_for(nipponese, 'ja')).to have_attributes(
             name: 'same_name', tag_id: nipponese.id, language_code: 'ja', primary_flg: true)
         expect(described_class.find_or_create_by_tag_name!(
-            locale, 'same_name', category: :general)).to eq(english)
+            locale, 'same_name', category: :general)).to eq(ainu)
         expect(described_class.find_or_create_by_tag_name!(
             Locale.nipponese, 'same_name', category: :general)).to eq(nipponese)
       end
 
       it 'preserves the V1 representative when looking up another primary language' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
         locale
         tag = create(:tag, primary_name: '日本語代表名')
-        representative_id = tag.tag_name_id
-        english = primary_tag_name_for(tag, 'en')
-        english.update!(name: 'english_primary', auto_generated: false)
+        representative_id = tag.tag_name('ja')&.id
+        ainu = primary_tag_name_for(tag, 'ain')
+        ainu.update!(name: 'ainu_primary', auto_generated: false)
 
         found = described_class.find_or_create_by_tag_name!(
-            locale, english.name, category: :general)
+            locale, ainu.name, category: :general)
 
         expect(found).to eq(tag)
-        expect(tag.reload.tag_name_id).to eq(representative_id)
-        expect(english.reload.tag_id).to eq(tag.id)
+        expect(tag.reload.tag_name('ja')&.id).to eq(representative_id)
+        expect(ainu.reload.tag_id).to eq(tag.id)
       end
 
       it 'normalises names using the supplied locale' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
         locale
         tags = described_class.normalise_tags!(
-            locale, ['character:normalised_english'],
+            locale, ['character:normalised_ainu'],
             with_tagme: false, with_no_deerjikist: false)
 
         expect(tags.length).to eq(1)
-        expect(primary_tag_name_for(tags.first, 'en')).to have_attributes(
-            name: 'normalised_english', language_code: 'en', script_code: 'Latn',
+        expect(primary_tag_name_for(tags.first, 'ain')).to have_attributes(
+            name: 'normalised_ainu', language_code: 'ain', script_code: 'Kana',
             primary_flg: true, tag_id: tags.first.id)
       end
     end
@@ -389,22 +384,10 @@ RSpec.describe Tag, type: :model do
       expect(primary_tag_name_for(tag, 'ja').auto_generated).to be(false)
     end
 
-    it 'promotes a detached Nipponese alias into a human-confirmed primary' do
-      detached = create(:tag_name, :alias, name: 'detached_nipponese')
-
-      tag = described_class.find_or_create_by_tag_name!(
-          Locale.nipponese, detached.name, category: :general)
-
-      expect(detached.reload).to have_attributes(
-          tag_id: tag.id, primary_flg: true, canonical_id: nil,
-          auto_generated: false)
-      expect(TagName.where(tag:, language_code: 'ja', primary_flg: true))
-          .to contain_exactly(detached)
-    end
 
     it 'reuses the owning tag for an alias without changing its category' do
       tag = create(:tag, category: :character)
-      representative_id = tag.tag_name_id
+      representative_id = tag.tag_name('ja')&.id
       alias_name = create(:tag_name, :alias, name: 'lookup_alias', tag:)
       expect(alias_name.reload).to have_attributes(
           tag_id: tag.id,
@@ -418,7 +401,7 @@ RSpec.describe Tag, type: :model do
 
       expect(found).to eq(tag)
       expect(found.category).to eq('character')
-      expect(tag.reload.tag_name_id).to eq(representative_id)
+      expect(tag.reload.tag_name('ja')&.id).to eq(representative_id)
     end
 
     it 'reuses the owning tag through another alias' do
@@ -451,26 +434,25 @@ RSpec.describe Tag, type: :model do
     end
 
     context 'with names in multiple languages' do
-      include_context 'English locale'
+      include_context 'Ainu locale'
 
       it 'keeps the target primary and moves source names as aliases' do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
         locale
-        english_primary = primary_tag_name_for(target_tag, 'en')
-        source_primary = primary_tag_name_for(source_tag, 'en')
+        ainu_primary = primary_tag_name_for(target_tag, 'ain')
+        source_primary = primary_tag_name_for(source_tag, 'ain')
         source_alias = create(:tag_name, :alias, tag: source_tag,
-            name: 'source_english_alias', language_code: 'en', script_code: 'Latn')
+            name: 'source_ainu_alias', language_code: 'ain', script_code: 'Kana')
 
-        expect([english_primary, source_primary]).to all(have_attributes(
+        expect([ainu_primary, source_primary]).to all(have_attributes(
             primary_flg: true, auto_generated: true))
 
         described_class.merge_tags!(target_tag, [source_tag])
 
-        expect(primary_tag_name_for(target_tag.reload, 'en')).to eq(english_primary)
-        expect(TagName.where(tag: target_tag, language_code: 'en', primary_flg: true))
-            .to contain_exactly(english_primary)
+        expect(primary_tag_name_for(target_tag.reload, 'ain')).to eq(ainu_primary)
+        expect(TagName.where(tag: target_tag, language_code: 'ain', primary_flg: true))
+            .to contain_exactly(ainu_primary)
         expect([source_primary.reload, source_alias.reload]).to all(have_attributes(
-            tag_id: target_tag.id, language_code: 'en', primary_flg: false))
+            tag_id: target_tag.id, language_code: 'ain', primary_flg: false))
         expect(TagName.where(tag: target_tag, language_code: 'ja', primary_flg: true))
             .to contain_exactly(primary_tag_name_for(target_tag, 'ja'))
         expect(source_tag_name.reload).to have_attributes(
@@ -642,7 +624,7 @@ RSpec.describe Tag, type: :model do
       let!(:wiki_page) do
         admin = create_admin_user!
 
-        Wiki::Commit.create_content!(
+        seed_description(
             tag_name: source_tag_name,
             body: 'source wiki body',
             created_by_user: admin,

backend/spec/models/user_spec.rb

@@ -0,0 +1,25 @@
+require 'rails_helper'
+
+RSpec.describe User, type: :model do
+  it 'nullifies description authorship without deleting native content or history' do
+    author = create_member_user!
+    editor = create_member_user!
+    tag = create(:tag)
+    description = TagDescriptionOperation.create!(
+        Locale.nipponese, tag:, body: 'initial', created_by_user: author)
+    TagDescriptionOperation.update!(
+        Locale.nipponese, tag:, body: 'edited', updated_by_user: editor)
+    versions = TagDescriptionVersion.where(tag_id: tag.id).order(:version_no)
+    snapshots = versions.map(&:attributes)
+
+    expect(author.created_tag_descriptions).to contain_exactly(description)
+    expect(editor.updated_tag_descriptions).to contain_exactly(description)
+    expect { author.destroy! }.to change(TagDescription, :count).by(0)
+        .and change(TagDescriptionVersion, :count).by(0)
+    expect(description.reload).to have_attributes(
+        body: 'edited', created_by_user_id: nil, updated_by_user_id: editor.id)
+    expect { editor.destroy! }.not_to change(TagDescription, :count)
+    expect(description.reload.updated_by_user_id).to be_nil
+    expect(versions.reload.map(&:attributes)).to eq(snapshots)
+  end
+end

backend/spec/requests/locale_resolution_spec.rb

@@ -0,0 +1,54 @@
+require 'rails_helper'
+
+RSpec.describe 'API locale resolution', type: :request do
+  let!(:tag) { create(:tag, primary_name: '日本語正本') }
+
+  it 'defaults an omitted locale to Japanese' do
+    get "/tags/#{ tag.id }"
+
+    expect(response).to have_http_status(:ok)
+    expect(json.fetch('name')).to eq('日本語正本')
+  end
+
+  it 'accepts an explicitly requested active Japanese locale' do
+    get "/tags/#{ tag.id }", params: { locale: 'ja' }
+
+    expect(response).to have_http_status(:ok)
+    expect(json.fetch('name')).to eq('日本語正本')
+  end
+
+  ['', 'en', 'ain', 'Jpan', 'JA', 'unknown', ['ja']].each do |code|
+    it "rejects invalid locale #{ code.inspect } instead of defaulting to Japanese" do
+      get "/tags/#{ tag.id }", params: { locale: code }
+
+      expect(response).to have_http_status(:not_found)
+      expect(response.body).not_to include('日本語正本')
+    end
+  end
+
+  it 'rejects a supported locale that has not been registered' do
+    get "/tags/#{ tag.id }", params: { locale: 'ain-Kana' }
+
+    expect(response).to have_http_status(:not_found)
+  end
+
+  it 'rejects an inactive locale' do
+    Locale.nipponese.update!(deprecated_at: Time.current)
+
+    get "/tags/#{ tag.id }", params: { locale: 'ja' }
+
+    expect(response).to have_http_status(:not_found)
+  end
+
+  it 'does not write posts or tag names under an invalid locale' do
+    sign_in_as(create_member_user!)
+
+    expect do
+      post '/posts', params: {
+          locale: 'en', title: 'invalid locale', url: 'https://example.com/invalid-locale',
+          tags: 'unwritten_tag' }
+    end.to change(Post, :count).by(0).and change(TagName, :count).by(0)
+
+    expect(response).to have_http_status(:not_found)
+  end
+end

backend/spec/requests/locale_write_paths_spec.rb

@@ -1,7 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Locale propagation on write paths', type: :request do
-  include_context 'English locale'
+  include_context 'Ainu locale'
 
   let(:member) { create(:user, :member) }
 
@@ -54,13 +54,12 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
     end
   end
 
-  ['en', nil].each do |requested_locale|
+  ['ain-Kana', nil].each do |requested_locale|
     context "with locale #{ requested_locale.inspect }" do
       let(:locale_params) { requested_locale ? { locale: requested_locale } : { } }
       let(:expected_locale) { requested_locale ? locale : Locale.nipponese }
 
       it 'creates post tags in the requested language or Nipponese fallback' do
-        pending '日本語以外の Locale 有効化は別課題で実装する' if requested_locale
         locale if requested_locale
         post '/posts', params: locale_params.merge(
             title: 'Locale post', url: 'https://example.com/locale-post',
@@ -72,7 +71,6 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
       end
 
       it 'updates post tags in the requested language or Nipponese fallback' do
-        pending '日本語以外の Locale 有効化は別課題で実装する' if requested_locale
         locale if requested_locale
         record = create(:post)
         PostVersionRecorder.record!(post: record, event_type: :create, created_by_user: member)
@@ -87,7 +85,6 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
       end
 
       it 'passes the resolved locale to bulk creation' do
-        pending '日本語以外の Locale 有効化は別課題で実装する' if requested_locale
         locale if requested_locale
         # Worker propagation is exercised in post_bulk_creator_spec.
         expect_any_instance_of(PostBulkCreator).to receive(:run)
@@ -102,7 +99,6 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
       end
 
       it 'creates materials with tags in the resolved locale' do
-        pending '日本語以外の Locale 有効化は別課題で実装する' if requested_locale
         locale if requested_locale
         post '/materials', params: locale_params.merge(
             tag: 'locale_material', url: 'https://example.com/material')
@@ -113,7 +109,6 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
       end
 
       it 'updates materials with tags in the resolved locale' do
-        pending '日本語以外の Locale 有効化は別課題で実装する' if requested_locale
         locale if requested_locale
         tag = create(:tag, category: :material)
         material = Material.create!(tag:, url: 'https://example.com/material')
@@ -127,7 +122,6 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
       end
 
       it 'links Nico external tags to internal tags in the resolved locale' do
-        pending '日本語以外の Locale 有効化は別課題で実装する' if requested_locale
         locale if requested_locale
         external = create(:external_tag)
         NicoTagVersionRecorder.record!(
@@ -141,7 +135,6 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
       end
 
       it 'creates parent tags in the resolved locale' do
-        pending '日本語以外の Locale 有効化は別課題で実装する' if requested_locale
         locale if requested_locale
         tag = create(:tag)
 
@@ -157,10 +150,10 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
   end
 
   context 'with existing names in both languages' do
-    let(:english_name) do
-      create(:tag_name, name: 'shared_name', language_code: 'en', script_code: 'Latn')
+    let(:ainu_name) do
+      create(:tag_name, name: 'shared_name', language_code: 'ain', script_code: 'Kana')
     end
-    let(:english_tag) { create(:tag, primary_tag_name: english_name, category: :material) }
+    let(:ainu_tag) { create(:tag, primary_tag_name: ainu_name, category: :material) }
     let(:nipponese_tag) do
       create(:tag, primary_name: 'temporary_nipponese', category: :general).tap do |tag|
         # Isolate lookup from the separately tested uniqueness validation.
@@ -168,173 +161,163 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
       end
     end
 
-    it 'plans and creates the post using the English identity and category' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
+    it 'plans and creates the post using the Ainu identity and category' do
       locale
-      english_tag
+      ainu_tag
       nipponese_tag
       post '/posts', params: {
-          locale: 'en', title: 'English identity',
-          url: 'https://example.com/english-identity', tags: 'shared_name', parent_post_ids: '' }
+          locale: 'ain-Kana', title: 'Ainu identity',
+          url: 'https://example.com/ainu-identity', tags: 'shared_name', parent_post_ids: '' }
 
       expect(response).to have_http_status(:created), response.body
       record = Post.find(json.fetch('id'))
-      expect(record.tags).to include(english_tag)
+      expect(record.tags).to include(ainu_tag)
       expect(record.tags).not_to include(nipponese_tag)
-      expect(english_tag.reload.category).to eq('material')
+      expect(ainu_tag.reload.category).to eq('material')
       expect(nipponese_tag.reload.category).to eq('general')
     end
 
-    it 'updates the post using the English identity' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
+    it 'updates the post using the Ainu identity' do
       locale
-      english_tag
+      ainu_tag
       nipponese_tag
       record = create(:post)
       PostVersionRecorder.record!(post: record, event_type: :create, created_by_user: member)
 
       put "/posts/#{ record.id }", params: {
-          locale: 'en', title: record.title, tags: 'shared_name', parent_post_ids: '',
+          locale: 'ain-Kana', title: record.title, tags: 'shared_name', parent_post_ids: '',
           base_version_no: record.reload.version_no }
 
       expect(response).to have_http_status(:ok), response.body
-      expect(record.reload.tags).to include(english_tag)
+      expect(record.reload.tags).to include(ainu_tag)
       expect(record.tags).not_to include(nipponese_tag)
     end
 
-    it 'resolves the English material tag' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
+    it 'resolves the Ainu material tag' do
       locale
-      english_tag
+      ainu_tag
       nipponese_tag
       post '/materials', params: {
-          locale: 'en', tag: 'shared_name', url: 'https://example.com/english-material' }
+          locale: 'ain-Kana', tag: 'shared_name', url: 'https://example.com/ainu-material' }
 
       expect(response).to have_http_status(:created), response.body
-      expect(Material.find(json.fetch('id')).tag).to eq(english_tag)
+      expect(Material.find(json.fetch('id')).tag).to eq(ainu_tag)
       expect(Material.where(tag: nipponese_tag)).to be_empty
     end
 
-    it 'resolves the English parent tag' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
+    it 'resolves the Ainu parent tag' do
       locale
-      english_tag
+      ainu_tag
       nipponese_tag
       child = create(:tag)
 
       put "/tags/#{ child.id }", params: {
-          locale: 'en', name: primary_tag_name_for(child, 'ja').name,
+          locale: 'ain-Kana', name: primary_tag_name_for(child, 'ja').name,
           category: child.category, deprecated: false,
           aliases: '', parent_tags: 'shared_name' }
 
       expect(response).to have_http_status(:ok), response.body
-      expect(TagImplication.where(tag: child).pluck(:parent_tag_id)).to eq([english_tag.id])
+      expect(TagImplication.where(tag: child).pluck(:parent_tag_id)).to eq([ainu_tag.id])
     end
 
-    it 'resolves the English internal tag for a Nico link' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
+    it 'resolves the Ainu internal tag for a Nico link' do
       locale
-      english_tag
+      ainu_tag
       nipponese_tag
       external = create(:external_tag)
       NicoTagVersionRecorder.record!(
           external_tag: external, event_type: :create, created_by_user: member)
 
-      put "/tags/nico/#{ external.id }", params: { locale: 'en', tags: 'shared_name' }
+      put "/tags/nico/#{ external.id }", params: { locale: 'ain-Kana', tags: 'shared_name' }
 
       expect(response).to have_http_status(:ok), response.body
-      expect(external.reload.linked_tags).to contain_exactly(english_tag)
+      expect(external.reload.linked_tags).to contain_exactly(ainu_tag)
     end
   end
 
-  context 'when renaming or updating aliases in English' do
-    let(:english_name) do
-      create(:tag_name, name: 'english_original', language_code: 'en', script_code: 'Latn')
+  context 'when renaming or updating aliases in Ainu' do
+    let(:ainu_name) do
+      create(:tag_name, name: 'ainu_original', language_code: 'ain', script_code: 'Kana')
     end
-    let(:tag) { create(:tag, primary_tag_name: english_name) }
+    let(:tag) { create(:tag, primary_tag_name: ainu_name) }
 
     it 'marks a human-renamed generated primary as no longer auto-generated' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
       locale
       generated_tag = create(:tag, primary_name: 'rename_generated_source')
-      generated_name = primary_tag_name_for(generated_tag, 'en')
+      generated_name = primary_tag_name_for(generated_tag, 'ain')
       expect(generated_name.auto_generated).to be(true)
 
       patch "/tags/#{ generated_tag.id }", params: {
-          locale: 'en', name: 'human_english_name' }
+          locale: 'ain-Kana', name: 'human_ainu_name' }
 
       expect(response).to have_http_status(:ok), response.body
       expect(generated_name.reload).to have_attributes(
-          name: 'human_english_name', auto_generated: false)
+          name: 'human_ainu_name', auto_generated: false)
     end
 
     it 'does not steal another tag primary for an alias' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
       locale
       other_tag = create(:tag, primary_name: 'other_nipponese')
-      other_primary = primary_tag_name_for(other_tag, 'en')
-      other_primary.update!(name: 'other_english_primary', auto_generated: false)
-      create(:tag_name, :alias, tag:, name: 'existing_english_alias',
-                                language_code: 'en', script_code: 'Latn')
-      primary_name_before = primary_tag_name_for(tag, 'en').name
+      other_primary = primary_tag_name_for(other_tag, 'ain')
+      other_primary.update!(name: 'other_ainu_primary', auto_generated: false)
+      create(:tag_name, :alias, tag:, name: 'existing_ainu_alias',
+                                language_code: 'ain', script_code: 'Kana')
+      primary_name_before = primary_tag_name_for(tag, 'ain').name
       aliases_before =
-          tag.tag_names.where(language_code: 'en', primary_flg: false)
+          tag.tag_names.where(language_code: 'ain', primary_flg: false)
               .order(:name).pluck(:name)
       category_before = tag.category
 
       put "/tags/#{ tag.id }", params: {
-          locale: 'en', name: 'renamed_before_alias_collision',
+          locale: 'ain-Kana', name: 'renamed_before_alias_collision',
           category: 'character', deprecated: false,
-          aliases: 'other_english_primary', parent_tags: '' }
+          aliases: 'other_ainu_primary', parent_tags: '' }
 
       aggregate_failures do
         expect(response).to have_http_status(:unprocessable_entity)
         expect(other_primary.reload).to have_attributes(
-            tag_id: other_tag.id, language_code: 'en', primary_flg: true)
-        expect(TagName.where(tag: other_tag, language_code: 'en', primary_flg: true))
+            tag_id: other_tag.id, language_code: 'ain', primary_flg: true)
+        expect(TagName.where(tag: other_tag, language_code: 'ain', primary_flg: true))
             .to contain_exactly(other_primary)
-        expect(primary_tag_name_for(tag.reload, 'en').name).to eq(primary_name_before)
+        expect(primary_tag_name_for(tag.reload, 'ain').name).to eq(primary_name_before)
         expect(tag.category).to eq(category_before)
         aliases_after =
-            tag.tag_names.where(language_code: 'en', primary_flg: false)
+            tag.tag_names.where(language_code: 'ain', primary_flg: false)
                 .order(:name).pluck(:name)
         expect(aliases_after).to eq(aliases_before)
       end
     end
 
     it 'allows a rename to a name already used in Nipponese' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
       locale
       nipponese = create(:tag, primary_name: 'rename_target')
 
-      patch "/tags/#{ tag.id }", params: { locale: 'en', name: 'rename_target' }
+      patch "/tags/#{ tag.id }", params: { locale: 'ain-Kana', name: 'rename_target' }
 
       expect(response).to have_http_status(:ok), response.body
-      expect(primary_tag_name_for(tag.reload, 'en')).to have_attributes(
-          name: 'rename_target', language_code: 'en', tag_id: tag.id)
+      expect(primary_tag_name_for(tag.reload, 'ain')).to have_attributes(
+          name: 'rename_target', language_code: 'ain', tag_id: tag.id)
       expect(primary_tag_name_for(nipponese.reload, 'ja')).to have_attributes(
           name: 'rename_target', language_code: 'ja', tag_id: nipponese.id)
     end
 
     it 'creates aliases in the requested language' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
       locale
       put "/tags/#{ tag.id }", params: {
-          locale: 'en', name: english_name.name,
+          locale: 'ain-Kana', name: ainu_name.name,
           category: tag.category, deprecated: false,
-          aliases: 'english_alias', parent_tags: '' }
+          aliases: 'ainu_alias', parent_tags: '' }
 
       expect(response).to have_http_status(:ok), response.body
-      expect(TagName.find_by!(language_code: 'en', name: 'english_alias'))
+      expect(TagName.find_by!(language_code: 'ain', name: 'ainu_alias'))
           .to have_attributes(
-              script_code: 'Latn',
-              tag_id: tag.id, primary_flg: false, language_code: 'en')
-      primary = TagName.find_by!(tag_id: tag.id, language_code: 'en', primary_flg: true)
-      expect(primary).to have_attributes(name: 'english_original', script_code: 'Latn')
+              script_code: 'Kana',
+              tag_id: tag.id, primary_flg: false, language_code: 'ain')
+      primary = TagName.find_by!(tag_id: tag.id, language_code: 'ain', primary_flg: true)
+      expect(primary).to have_attributes(name: 'ainu_original', script_code: 'Kana')
     end
 
     it 'does not take an alias from another language' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
       locale
       nipponese = create(:tag, primary_name: 'nipponese_owner')
       nipponese_alias = create(:tag_name, :alias, name: 'shared_alias',
@@ -344,7 +327,7 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
           primary_flg: false, language_code: 'ja')
 
       put "/tags/#{ tag.id }", params: {
-          locale: 'en', name: english_name.name,
+          locale: 'ain-Kana', name: ainu_name.name,
           category: tag.category, deprecated: false,
           aliases: 'shared_alias', parent_tags: '' }
 
@@ -352,12 +335,12 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
       expect(nipponese_alias.reload).to have_attributes(
           tag_id: nipponese.id,
           primary_flg: false, language_code: 'ja')
-      expect(TagName.find_by!(language_code: 'en', name: 'shared_alias'))
+      expect(TagName.find_by!(language_code: 'ain', name: 'shared_alias'))
           .to have_attributes(
-              tag_id: tag.id, script_code: 'Latn',
-              primary_flg: false, language_code: 'en')
+              tag_id: tag.id, script_code: 'Kana',
+              primary_flg: false, language_code: 'ain')
       expect(TagName.where(name: 'shared_alias').pluck(:language_code, :tag_id))
-          .to contain_exactly(['ja', nipponese.id], ['en', tag.id])
+          .to contain_exactly(['ja', nipponese.id], ['ain', tag.id])
     end
   end
 end

backend/spec/requests/materials_spec.rb

@@ -178,6 +178,7 @@ RSpec.describe 'Materials API', type: :request do
   end
 
   describe 'GET /materials/:id' do
+    include WikiRecords
     let!(:tag) do
       create(:tag, primary_name: 'material_show', category: :material)
     end
@@ -205,6 +206,54 @@ RSpec.describe 'Materials API', type: :request do
       get '/materials/999999999'
       expect(response).to have_http_status(:not_found)
     end
+
+    def get_material_without_legacy_reads
+      queries = []
+      subscriber = lambda do |*args|
+        sql = args.last.fetch(:sql)
+        if sql.match?(/\bSELECT\b/i) && sql.match?(/\bwiki_(pages|revisions|versions)\b/i)
+          queries << sql
+        end
+      end
+      ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') do
+        get "/materials/#{ material.id }"
+      end
+      expect(response).to have_http_status(:ok)
+      expect(queries).to be_empty
+    end
+
+    it 'reads the description even when the stored version has different content' do
+      page = seed_description(tag_name: tag.tag_name('ja'), body: 'legacy body',
+                            created_by_user: member_user)
+      TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
+          .update!(body: 'description body')
+      get_material_without_legacy_reads
+      expect(json.fetch('wiki_page_body')).to eq('description body')
+      expect(current_description_version(page).body).to eq('legacy body')
+    end
+
+    it 'uses tag_id rather than description Id. without a Wiki page' do
+      description = TagDescription.create!(tag:, language_code: 'ja',
+                                           body: 'independent body', version_no: 1)
+      get_material_without_legacy_reads
+      expect(json.fetch('wiki_page_body')).to eq('independent body')
+      expect(json.fetch('tag').fetch('has_wiki')).to be(true)
+    end
+
+    it 'returns nil when only description history remains' do
+      seed_description(tag_name: tag.tag_name('ja'), body: 'legacy only',
+                     created_by_user: member_user)
+      TagDescription.where(tag_id: tag.id).delete_all
+      get_material_without_legacy_reads
+      expect(json.fetch('wiki_page_body')).to be_nil
+      expect(json.fetch('tag').fetch('has_wiki')).to be(false)
+    end
+
+    it 'returns nil for an untagged material' do
+      material.update!(tag: nil)
+      get_material_without_legacy_reads
+      expect(json.fetch('wiki_page_body')).to be_nil
+    end
   end
 
   describe 'POST /materials' do

backend/spec/requests/tag_description_wiki_spec.rb

@@ -1,36 +1,24 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag description Wiki compatibility', type: :request do
+  include WikiRecords
   let!(:user) { create_member_user! }
   let!(:tag_name) { create(:tag_name, name: 'description_contract') }
-  let!(:page) do
-    Wiki::Commit.create_content!(
-        tag_name:, body: 'old-revision', created_by_user: user)
-  end
-  let!(:revisions) do
-    first = page.current_revision
-    second = Wiki::Commit.content!(page:, body: 'old-second', created_user: user)
-    third = Wiki::Commit.content!(page:, body: 'old-third', created_user: user)
-    [first, second, third]
-  end
-  let!(:tag) { create(:tag, primary_tag_name: tag_name) }
+  let!(:tag) { tag_name.tag }
   let!(:versions) do
-    revisions.each_with_index.map do |revision, index|
+    ['A', 'A', 'new-version'].each_with_index.map do |body, index|
       TagDescriptionVersion.create!(
-          id: revision.id, tag_id: tag.id, language_code: 'ja',
-          version_no: index + 1, event_type: index.zero? ? 'create' : 'update',
-          body: index == 2 ? 'new-version' : 'A',
-          created_by_user_id: user.id, created_at: revision.created_at)
+          tag_id: tag.id, language_code: 'ja', version_no: index + 1,
+          event_type: index.zero? ? 'create' : 'update', body:,
+          created_by_user_id: user.id, created_at: Time.current)
     end
   end
   let!(:description) do
     TagDescription.create!(
-        id: page.id, tag:, language_code: 'ja', version_no: 3, body: 'new',
+        tag:, language_code: 'ja', version_no: 3, body: 'new',
         created_by_user_id: user.id, updated_by_user_id: user.id)
   end
 
-  before { page.update_columns(body: 'old') }
-
   # Observe real SELECTs, including cached queries, only during the request.
   def without_legacy_reads
     queries = []
@@ -69,7 +57,7 @@ RSpec.describe 'Tag description Wiki compatibility', type: :request do
     it 'does not fall back to a revision absent from new history' do
       versions.first.destroy!
       without_legacy_reads do
-        get "/wiki/#{ description.id }", params: { version: revisions.first.id }
+        get "/wiki/#{ description.id }", params: { version: versions.first.id }
       end
       expect(response).to have_http_status(:not_found)
     end
@@ -131,16 +119,6 @@ RSpec.describe 'Tag description Wiki compatibility', type: :request do
                              'pred' => versions.first.id, 'succ' => versions.last.id)
     end
 
-    it 'ignores changes to same-title legacy content and revision metadata' do
-      get "/wiki/title/#{ tag_name.name }"
-      original = json
-      page.update_columns(body: 'changed legacy body')
-      revisions.last.update_columns(message: 'legacy message', created_at: 1.day.ago)
-      revisions.last.wiki_lines.update_all(body: 'changed legacy revision')
-      get "/wiki/title/#{ tag_name.name }"
-      expect(json).to eq(original)
-      expect(json.fetch('body')).to eq('new')
-    end
   end
 
   describe 'exists' do
@@ -154,28 +132,6 @@ RSpec.describe 'Tag description Wiki compatibility', type: :request do
       expect(response).to have_http_status(:no_content)
     end
 
-    context 'without a legacy page' do
-      before do
-        WikiVersion.where(wiki_page_id: page.id).delete_all
-        page.destroy!
-      end
-
-      it 'recognises the description ID alone' do
-        get "/wiki/#{ description.id }/exists"
-        expect(response).to have_http_status(:no_content)
-      end
-
-      it 'recognises the TagName alone' do
-        get "/wiki/title/#{ tag_name.name }/exists"
-        expect(response).to have_http_status(:no_content)
-      end
-
-      it 'shows the description by title' do
-        get "/wiki/title/#{ tag_name.name }"
-        expect(response).to have_http_status(:ok)
-        expect(json).to include('body' => 'new', 'revision_id' => versions.last.id)
-      end
-    end
   end
 
   describe 'diff' do
@@ -228,39 +184,8 @@ RSpec.describe 'Tag description Wiki compatibility', type: :request do
                                                       'title' => tag_name.name)
     end
 
-    it 'ignores legacy-only revisions and metadata changes' do
-      get '/wiki/changes', params: { id: description.id }
-      original = json
-      revisions.first.update_columns(message: 'legacy changed', created_at: 1.day.ago)
-      WikiRevision.create!(
-          wiki_page: page, created_user: user, kind: :content,
-          tree_sha256: Digest::SHA256.hexdigest('legacy only'), lines_count: 0)
-      get '/wiki/changes', params: { id: description.id }
-      expect(json).to eq(original)
-      expect(json.map { |row| row.fetch('revision_id') }).to eq(versions.reverse.map(&:id))
-    end
   end
 
-  describe 'mixed changes' do
-    it 'includes unmigrated history and ignores migrated legacy-only revisions' do
-      legacy_page = Wiki::Commit.create_content!(
-          tag_name: create(:tag_name, name: 'Help_mixed'),
-          body: 'help', created_by_user: user)
-      legacy_revision = legacy_page.current_revision
-      extra = WikiRevision.create!(
-          wiki_page: page, created_user: user, kind: :content,
-          tree_sha256: Digest::SHA256.hexdigest('legacy only'), lines_count: 0)
-
-      get '/wiki/changes'
-      expect(response).to have_http_status(:ok)
-      migrated = json.select { |row| row.fetch('wiki_page').fetch('id') == description.id }
-      expect(migrated.map { |row| row.fetch('revision_id') }).to eq(versions.reverse.map(&:id))
-      expect(json.map { |row| row.fetch('revision_id') }).not_to include(extra.id)
-      expect(json).to include(include(
-          'revision_id' => legacy_revision.id,
-          'wiki_page' => include('id' => legacy_page.id, 'title' => 'Help_mixed')))
-    end
-  end
 
   describe 'index' do
     [nil, 'description_contract'].each do |title|

backend/spec/requests/tag_description_wiki_write_spec.rb

@@ -1,273 +1,93 @@
 require 'rails_helper'
 
-RSpec.describe 'Tag description Wiki dual writes', type: :request do
+RSpec.describe 'Tag description Wiki facade writes', type: :request do
+  include WikiRecords
   let!(:user) { create_member_user! }
-  let!(:tag_name) { create(:tag_name, name: 'description_write') }
-  let(:tag) { create(:tag, primary_tag_name: tag_name) }
+  let!(:tag) { create(:tag, primary_name: 'description_write') }
   let(:headers) { { 'X-Transfer-Code' => user.inheritance_code } }
 
   def stored_state
-    [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion,
-     TagName, TagVersion].map do |model|
+    [Tag, TagName, TagVersion, TagDescription, TagDescriptionVersion].map do |model|
       model.order(:id).map(&:attributes)
     end
   end
 
-  # Fail after a real INSERT/UPDATE, exercising rollback rather than a mock write.
-  def fail_save model
-    failure = Class.new(StandardError)
-    callback = ->(_record) { raise failure, 'injected persistence failure' }
-    model.set_callback(:save, :after, callback)
-    expect { yield }.to raise_error(failure)
-  ensure
-    model.skip_callback(:save, :after, callback)
+  it 'creates a native description and exposes its version ID as revision ID' do
+    expect do
+      post '/wiki', params: { title: tag.name('ja'), body: 'initial' }, headers: headers
+    end.to change(TagDescription, :count).by(1)
+        .and change(TagDescriptionVersion, :count).by(1)
+    expect(response).to have_http_status(:created)
+    description = TagDescription.find(json.fetch('id'))
+    expect(description).to have_attributes(tag_id: tag.id, body: 'initial', version_no: 1)
+    get "/wiki/#{ description.id }"
+    expect(json.fetch('revision_id')).to eq(current_description_version(description).id)
   end
 
-  describe 'POST /wiki' do
-    before { tag }
+  context 'with an existing description' do
+    let!(:description) do
+      TagDescriptionOperation.create!(
+          Locale.nipponese, tag:, body: 'before', created_by_user: user)
+    end
+    let!(:first_version) { current_description_version(description) }
 
-    def create_description
-      post '/wiki', params: { title: tag_name.name, body: 'initial', message: 'create' },
-           headers: headers
+    def update_description body: 'after', title: tag.name('ja'), base: first_version.id
+      put "/wiki/#{ description.id }", params: { title:, body:, base_revision_id: base },
+          headers: headers
     end
 
-    it 'creates both current records and histories with a shared revision ID' do
-      expect { create_description }
-          .to change(WikiPage, :count).by(1)
-          .and change(WikiRevision, :count).by(1)
-          .and change(WikiVersion, :count).by(1)
-          .and change(TagDescription, :count).by(1)
-          .and change(TagDescriptionVersion, :count).by(1)
-      expect(response).to have_http_status(:created)
-
-      page = WikiPage.find(json.fetch('id'))
-      description = TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
-      version = TagDescriptionVersion.find_by!(tag_id: tag.id, language_code: 'ja')
-      expect(description).to have_attributes(id: page.id, body: 'initial', version_no: 1)
-      expect(version).to have_attributes(
-          id: page.current_revision.id, body: 'initial', version_no: 1,
-          event_type: 'create', created_by_user_id: user.id)
-      expect(page.body).to eq(description.body)
-      expect(page.current_revision.body).to eq(version.body)
-      expect(page.wiki_versions.last.body).to eq(version.body)
+    it 'records a body change without changing resource identity or old history' do
+      snapshot = first_version.attributes
+      expect { update_description }.to change(TagDescriptionVersion, :count).by(1)
+      expect(response).to have_http_status(:ok)
+      expect(description.reload).to have_attributes(body: 'after', version_no: 2)
+      expect(first_version.reload.attributes).to eq(snapshot)
+      expect(current_description_version(description)).to have_attributes(
+          body: 'after', event_type: 'update', created_by_user_id: user.id)
     end
 
-    ['missing_description', 'orphan_description'].each do |title|
-      it "rejects the bare title #{ title } without writing any resource" do
-        create(:tag_name, name: title) if title == 'orphan_description'
+    ['before', "before\r\n\r\n"].each do |body|
+      it "does not write for normalised-equivalent body #{ body.inspect }" do
         before_state = stored_state
-
-        post '/wiki', params: { title:, body: 'initial' }, headers: headers
-
-        expect(response).to have_http_status(:unprocessable_entity)
-        expect(json).to include('type' => 'validation_error')
+        update_description(body:)
+        expect(response).to have_http_status(:ok)
         expect(stored_state).to eq(before_state)
       end
     end
 
-    it 'creates a namespaced legacy Wiki resource without a Tag' do
-      expect do
-        post '/wiki', params: { title: 'Help:description_write', body: 'legacy' },
-             headers: headers
-      end.to change(WikiPage, :count).by(1)
-          .and change(WikiRevision, :count).by(1)
-          .and change(WikiVersion, :count).by(1)
-          .and change(TagDescription, :count).by(0)
+    it 'records a title-only edit in Tag history without adding body history' do
+      snapshot = description.attributes
+      expect { update_description(body: 'before', title: 'renamed') }
+          .to change(TagVersion, :count).by(2)
           .and change(TagDescriptionVersion, :count).by(0)
-
-      expect(response).to have_http_status(:created)
-      page = WikiPage.find(json.fetch('id'))
-      expect(page.tag_name.tag).to be_nil
-      expect(page.body).to eq('legacy')
-      expect(page.current_revision.body).to eq('legacy')
-    end
-
-    it 'creates only legacy Wiki for a namespaced title with an existing Tag' do
-      namespaced_name = create(:tag_name, name: 'help:foo')
-      namespaced_tag = create(:tag, primary_tag_name: namespaced_name)
-
-      expect do
-        post '/wiki', params: { title: namespaced_name.name, body: 'legacy' },
-             headers: headers
-      end.to change(WikiPage, :count).by(1)
-          .and change(WikiRevision, :count).by(1)
-          .and change(WikiVersion, :count).by(1)
-          .and change(TagName, :count).by(0)
-          .and change(TagDescription, :count).by(0)
-          .and change(TagDescriptionVersion, :count).by(0)
-
-      expect(response).to have_http_status(:created)
-      page = WikiPage.find(json.fetch('id'))
-      expect(page).to have_attributes(tag_name_id: namespaced_name.id, body: 'legacy')
-      expect(page.tag_name.tag).to eq(namespaced_tag)
-      expect(page.current_revision.body).to eq('legacy')
-      expect(page.wiki_versions.last.body).to eq('legacy')
-    end
-
-    [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion].each do |model|
-      it "rolls back both systems when #{ model.name } persistence fails" do
-        tag_name
-        before_state = stored_state
-        aggregate_failures do
-          fail_save(model) { create_description }
-          expect(stored_state).to eq(before_state)
-        end
-      end
-    end
-  end
-
-  describe 'PUT /wiki/:id' do
-    let!(:page) do
-      tag
-      Wiki::Commit.create_content!(
-          tag_name:, body: 'before', created_by_user: user)
-    end
-    let!(:first_revision) { page.current_revision }
-
-    let!(:description) do
-      TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
-    end
-
-    def update_description body: 'after', title: tag_name.name, base: first_revision.id
-      put "/wiki/#{ page.id }",
-          params: { title:, body:, message: 'edit', base_revision_id: base },
-          headers: headers
-    end
-
-    it 'increments the independent description sequence and shares revision identity' do
-      expect(page.reload.version_no).to eq(1)
-      expect(description.version_no).to eq(1)
-      expect { update_description }
-          .to change(WikiRevision, :count).by(1)
-          .and change(WikiVersion, :count).by(1)
-          .and change(TagDescriptionVersion, :count).by(1)
       expect(response).to have_http_status(:ok)
-
-      revision = page.reload.current_revision
-      version = TagDescriptionVersion.find(revision.id)
-      expect(description.reload).to have_attributes(body: 'after', version_no: 2)
-      expect(version).to have_attributes(
-          body: 'after', version_no: 2, event_type: 'update', created_by_user_id: user.id)
-      expect(page).to have_attributes(body: 'after', version_no: 2)
-      expect(revision.body).to eq(version.body)
-      expect(page.wiki_versions.order(:version_no).last.body).to eq(version.body)
+      expect(tag.reload.name('ja')).to eq('renamed')
+      expect(description.reload.attributes).to eq(snapshot)
     end
 
-    it 'uses description identity even when its Wiki TagName no longer owns the Tag' do
-      tag_name.update_columns(tag_id: nil)
-
-      expect { update_description }
-          .to change(WikiRevision, :count).by(1)
-          .and change(WikiVersion, :count).by(1)
-          .and change(TagDescriptionVersion, :count).by(1)
-
-      expect(response).to have_http_status(:ok)
-      expect(description.reload).to have_attributes(body: 'after', version_no: 2)
-      expect(TagDescriptionVersion.find(page.reload.current_revision.id))
-          .to have_attributes(tag_id: tag.id, body: 'after', version_no: 2)
-    end
-
-    it 'does not add body history for a title-only update' do
-      revision_count = WikiRevision.count
-      wiki_version_count = WikiVersion.count
-      description_version_count = TagDescriptionVersion.count
-      wiki_version_no = page.reload.version_no
-      description_version_no = description.version_no
-      current_revision_id = page.current_revision.id
-      page_state = page.attributes
-      description_state = description.attributes
-
-      update_description(body: 'before', title: 'Help:description_renamed')
-
-      expect(response).to have_http_status(:ok)
-      expect(tag_name.reload.name).to eq('Help:description_renamed')
-      expect(WikiRevision.count).to eq(revision_count)
-      expect(WikiVersion.count).to eq(wiki_version_count)
-      expect(TagDescriptionVersion.count).to eq(description_version_count)
-      expect(page.reload).to have_attributes(body: 'before', version_no: wiki_version_no)
-      expect(page.current_revision.id).to eq(current_revision_id)
-      expect(page.reload.attributes).to eq(page_state)
-      expect(description.reload).to have_attributes(
-          body: 'before', version_no: description_version_no)
-      expect(description.reload.attributes).to eq(description_state)
-    end
-
-    it 'does not add body history for a TagName rename through tags' do
-      revision_count = WikiRevision.count
-      wiki_version_count = WikiVersion.count
-      description_version_count = TagDescriptionVersion.count
-      page_version_no = page.reload.version_no
-      current_revision_id = page.current_revision.id
-
-      patch "/tags/#{ tag.id }",
-            params: { name: 'description_tag_renamed' },
-            headers: headers
-
-      expect(response).to have_http_status(:ok)
-      expect(tag_name.reload.name).to eq('description_tag_renamed')
-      expect(WikiRevision.count).to eq(revision_count)
-      expect(WikiVersion.count).to eq(wiki_version_count)
-      expect(TagDescriptionVersion.count).to eq(description_version_count)
-      expect(page.reload.version_no).to eq(page_version_no)
-      expect(page.current_revision.id).to eq(current_revision_id)
-      expect(description.reload).to have_attributes(
-          body: 'before', version_no: 1)
-    end
-
-    it 'keeps both systems and the title unchanged on a stale revision conflict' do
-      update_description(body: 'current body', base: first_revision.id)
-      expect(response).to have_http_status(:ok)
-
-      stale_revision_id = first_revision.id
-      before_state = stored_state
-
-      update_description(
-          body: 'conflicting body',
-          title: 'conflicting_rename',
-          base: stale_revision_id)
-
-      expect(response).to have_http_status(:conflict)
-      expect(stored_state).to eq(before_state)
-      expect(tag_name.reload.name).not_to eq('conflicting_rename')
-    end
-
-    [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion].each do |model|
-      it "rolls back both systems when #{ model.name } persistence fails" do
-        before_state = stored_state
-        aggregate_failures do
-          fail_save(model) do
-            update_description(body: 'rollback body', title: 'rollback_rename')
-          end
-          expect(stored_state).to eq(before_state)
-        end
-      end
-    end
-
-    [['identical body', 'before'],
-     ['normalised-equivalent body', "before\n\n"]].each do |label, body|
-      it "does not write histories for #{ label }" do
-        before_state = stored_state
-        page_state = page.reload.attributes
-        description_state = description.reload.attributes
-        current_revision_id = page.current_revision.id
-        wiki_lines = WikiLine.order(:id).map(&:attributes)
-        revision_lines = WikiRevisionLine.order(:id).map(&:attributes)
-        page_version_no = page.version_no
-        description_version_no = description.version_no
-
-        update_description(body:)
-
+    ['conflicting body', 'after'].each do |body|
+      it "rejects a stale revision even for #{ body } without a partial rename" do
+        update_description
         expect(response).to have_http_status(:ok)
-        expect(WikiRevision.count).to eq(before_state[1].length)
-        expect(WikiVersion.count).to eq(before_state[2].length)
-        expect(TagDescriptionVersion.count).to eq(before_state[4].length)
-        expect(page.reload.version_no).to eq(page_version_no)
-        expect(description.reload.version_no).to eq(description_version_no)
-        expect(page.current_revision.id).to eq(current_revision_id)
-        expect(page.reload.attributes).to eq(page_state)
-        expect(description.reload.attributes).to eq(description_state)
-        expect(WikiLine.order(:id).map(&:attributes)).to eq(wiki_lines)
-        expect(WikiRevisionLine.order(:id).map(&:attributes)).to eq(revision_lines)
+        before_state = stored_state
+        update_description(body:, title: 'conflicting rename')
+        expect(response).to have_http_status(:conflict)
+        expect(stored_state).to eq(before_state)
+      end
+    end
+
+    [TagDescription, TagDescriptionVersion].each do |model|
+      it "rolls back the rename and body after #{ model.name } persistence fails" do
+        before_state = stored_state
+        failure = Class.new(StandardError)
+        callback = ->(_record) { raise failure }
+        model.set_callback(:save, :after, callback)
+        begin
+          expect { update_description(title: 'rollback rename') }.to raise_error(failure)
+          expect(stored_state).to eq(before_state)
+        ensure
+          model.skip_callback(:save, :after, callback)
+        end
       end
     end
   end

backend/spec/requests/tag_descriptions_spec.rb

@@ -1,6 +1,8 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag description native API', type: :request do
+  include WikiRecords
+  include TagGroupRecords
   let!(:author) { create_member_user! }
   let(:editor) { create(:user, :member, name: 'description editor') }
   let(:tag_name) { create(:tag_name, name: 'native_description') }
@@ -9,8 +11,7 @@ RSpec.describe 'Tag description native API', type: :request do
   let(:endpoint) { "/tags/#{ tag.id }/description" }
 
   def stored_state
-    [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion,
-     WikiLine, WikiRevisionLine, TagName, TagVersion].map do |model|
+    [TagDescription, TagDescriptionVersion, TagName, TagVersion].map do |model|
       model.order(:id).map(&:attributes)
     end
   end
@@ -84,7 +85,7 @@ RSpec.describe 'Tag description native API', type: :request do
   describe 'native reads' do
     let!(:description) do
       TagDescription.create!(
-          id: tag.id + 1_000_000, tag:, language_code: 'ja', body: 'native current',
+          tag:, language_code: 'ja', body: 'native current',
           version_no: 1, created_by_user_id: author.id, updated_by_user_id: editor.id)
     end
     let!(:version) do
@@ -95,15 +96,14 @@ RSpec.describe 'Tag description native API', type: :request do
     let(:name_endpoint) { "/tags/name/#{ tag_name.name }/description" }
 
     it 'reads the current resource by Tag ID without a WikiPage' do
-      expect(description.id).not_to eq(tag.id)
-      expect(WikiPage.exists?(id: description.id)).to be(false)
       without_legacy_reads { native_get(endpoint) }
       expect(response).to have_http_status(:ok)
       expect_current(description)
     end
 
     it 'does not interpret a compatibility handle as a Tag ID' do
-      other_tag = create(:tag, id: description.id, primary_name: 'handle_collision')
+      other_tag = create(:tag, primary_name: 'handle_collision')
+      description.update_columns(id: other_tag.id)
       other = TagDescription.create!(
           tag: other_tag, language_code: 'ja', body: 'other current', version_no: 1,
           created_by_user_id: author.id, updated_by_user_id: author.id)
@@ -153,32 +153,6 @@ RSpec.describe 'Tag description native API', type: :request do
       expect_current(description)
     end
 
-    [:id, :name].each do |lookup|
-      it "ignores divergent legacy body and history for #{ lookup } lookup" do
-        page = WikiPage.create!(
-            id: description.id, tag_name:, body: 'old current',
-            created_user: author, updated_user: author)
-        revision = WikiRevision.create!(
-            wiki_page: page, created_user: author, kind: :content,
-            lines_count: 1, tree_sha256: Digest::SHA256.hexdigest('old revision'))
-        line = WikiLine.create!(body: 'old revision', sha256: revision.tree_sha256)
-        WikiRevisionLine.create!(wiki_revision: revision, wiki_line: line, position: 0)
-        WikiVersionRecorder.record!(page:, event_type: :create, created_by_user: author)
-        path = lookup == :id ? endpoint : name_endpoint
-        action = lookup == :id ? 'show' : 'show_by_title'
-
-        without_legacy_reads { native_get(path, action:) }
-        expect(response).to have_http_status(:ok)
-        expect_current(description)
-        original = json
-        page.update_columns(body: 'changed old current')
-        line.update_columns(body: 'changed old revision')
-        revision.update_columns(message: 'changed old history', created_at: 1.day.ago)
-        without_legacy_reads { native_get(path, action:) }
-        expect(response).to have_http_status(:ok)
-        expect(json).to eq(original)
-      end
-    end
   end
 
   describe 'missing native resources' do
@@ -206,35 +180,24 @@ RSpec.describe 'Tag description native API', type: :request do
     context 'without an existing description' do
       before { tag }
 
-      it 'creates both current resources and histories with matching compatibility IDs' do
+
+      it 'creates native history that is immediately available through the facade' do
         expect { native_write(body: 'created natively') }
             .to change(TagDescription, :count).by(1)
             .and change(TagDescriptionVersion, :count).by(1)
-            .and change(WikiPage, :count).by(1)
-            .and change(WikiRevision, :count).by(1)
-            .and change(WikiVersion, :count).by(1)
         expect(response).to have_http_status(:created)
         description = TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
-        page = WikiPage.find(description.id)
-        revision = page.current_revision
-        version = TagDescriptionVersion.find(revision.id)
-        expect(description).to have_attributes(
-            body: 'created natively', version_no: 1,
-            created_by_user_id: editor.id, updated_by_user_id: editor.id)
-        expect(version).to have_attributes(
-            tag_id: tag.id, language_code: 'ja', body: description.body,
-            version_no: 1, event_type: 'create', created_by_user_id: editor.id)
-        expect(page).to have_attributes(tag_name_id: tag_name.id, body: description.body)
-        expect(revision.body).to eq(version.body)
-        expect(page.wiki_versions.last.body).to eq(version.body)
         expect_current(description)
-
+        version = current_description_version(description)
+        expect(version).to have_attributes(
+            body: 'created natively', version_no: 1, event_type: 'create',
+            created_by_user_id: editor.id)
         get "/wiki/#{ description.id }"
         expect(response).to have_http_status(:ok)
         expect(json).to include('body' => description.body, 'revision_id' => version.id)
       end
 
-      [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion].each do |model|
+      [TagDescription, TagDescriptionVersion].each do |model|
         it "rolls back native create when #{ model.name } persistence fails" do
           headers
           before_state = stored_state
@@ -249,7 +212,7 @@ RSpec.describe 'Tag description native API', type: :request do
     context 'with an existing description' do
       let!(:page) do
         tag
-        Wiki::Commit.create_content!(tag_name:, body: 'before', created_by_user: author)
+        seed_description(tag_name:, body: 'before', created_by_user: author)
       end
       let!(:description) do
         TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
@@ -259,22 +222,20 @@ RSpec.describe 'Tag description native API', type: :request do
         expect(page.reload.version_no).to eq(1)
         expect(description.version_no).to eq(1)
         expect { native_write(body: 'after') }
-            .to change(WikiRevision, :count).by(1)
-            .and change(WikiVersion, :count).by(1)
-            .and change(TagDescriptionVersion, :count).by(1)
+            .to change(TagDescriptionVersion, :count).by(1)
         expect(response).to have_http_status(:ok)
         expect(description.reload).to have_attributes(
             body: 'after', version_no: 2,
             created_by_user_id: author.id, updated_by_user_id: editor.id)
         expect(page.reload).to have_attributes(body: 'after', version_no: 2)
 
-        revision = page.current_revision
+        revision = current_description_version(page)
         version = TagDescriptionVersion.find(revision.id)
         expect(version).to have_attributes(
             tag_id: tag.id, language_code: 'ja', version_no: 2, event_type: 'update',
             body: 'after', created_by_user_id: editor.id)
         expect(revision.body).to eq(version.body)
-        expect(page.wiki_versions.order(:version_no).last.body).to eq(version.body)
+        expect(description_versions(page).order(:version_no).last.body).to eq(version.body)
         get "/wiki/#{ description.id }"
         expect(response).to have_http_status(:ok)
         expect(json).to include('body' => 'after', 'revision_id' => version.id)
@@ -285,7 +246,7 @@ RSpec.describe 'Tag description native API', type: :request do
           before_state = stored_state
           page_state = page.reload.attributes
           description_state = description.reload.attributes
-          current_revision_id = page.current_revision.id
+          current_revision_id = current_description_version(page).id
 
           native_write(body:)
 
@@ -293,11 +254,11 @@ RSpec.describe 'Tag description native API', type: :request do
           expect(stored_state).to eq(before_state)
           expect(page.reload.attributes).to eq(page_state)
           expect(description.reload.attributes).to eq(description_state)
-          expect(page.current_revision.id).to eq(current_revision_id)
+          expect(current_description_version(page).id).to eq(current_revision_id)
         end
       end
 
-      [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion].each do |model|
+      [TagDescription, TagDescriptionVersion].each do |model|
         it "rolls back native update when #{ model.name } persistence fails" do
           headers
           before_state = stored_state

backend/spec/requests/tag_group_locale_spec.rb

@@ -0,0 +1,123 @@
+require 'rails_helper'
+
+RSpec.describe 'Tag group locale contracts', type: :request do
+  include TagGroupRecords
+  include_context 'Ainu locale contract'
+
+  let!(:user) { create_member_user! }
+  let!(:tag) { create(:tag, primary_name: 'japanese_member') }
+  let!(:ainu_name) { add_ainu_name(tag, 'ainu_member') }
+  let(:headers) { { 'X-Transfer-Code' => user.inheritance_code } }
+  let(:members) { [{ 'tag_id' => tag.id }] }
+  let(:placements) do
+    [{ 'section_name' => 'section', 'description' => nil, 'children' => [
+        { 'tag_id' => tag.id, 'children' => [
+            { 'tag_id' => tag.id, 'children' => [] }] }] }]
+  end
+  let!(:group) do
+    TagVersioning.ensure_snapshot!(tag, created_by_user: user)
+    TagGroupOperation.create!(
+        ainu_locale, name: 'locale group', description: nil, members:, placements:, actor: user)
+  end
+
+  it 'uses selected-language names in native collection and nested placements' do
+    ["/tag_groups/#{ group.id }", '/tag_groups'].each do |path|
+      get path, params: { locale: 'ain-Kana' }
+      expect(response).to have_http_status(:ok)
+      representation = json.is_a?(Array) ? json.sole : json
+      expect(representation.fetch('members').sole.fetch('tag').fetch('name'))
+          .to eq('ainu_member')
+      node = representation.fetch('placements').sole.fetch('children').sole
+      expect(node.fetch('tag').fetch('name')).to eq('ainu_member')
+      expect(node.fetch('children').sole.fetch('tag').fetch('name')).to eq('ainu_member')
+      expect(response.body).not_to include('japanese_member')
+    end
+  end
+
+  it 'uses snapshot names recursively for history and current names for the latest view' do
+    version = group.versions.sole
+    ainu_name.update!(name: 'renamed_ainu')
+    get "/wiki/#{ group.id }", params: { locale: 'ain-Kana' }
+    expect(response).to have_http_status(:ok)
+    expect(json.fetch('body')).to include('renamed_ainu')
+    get "/wiki/#{ group.id }", params: { locale: 'ain-Kana', version: version.id }
+    expect(response).to have_http_status(:ok)
+    expect(json.fetch('body').scan('ainu_member').length).to eq(2)
+    expect(json.fetch('body')).not_to include('renamed_ainu', 'japanese_member')
+    get "/wiki/#{ group.id }/diff", params: { locale: 'ain-Kana', from: version.id }
+    expect(response).to have_http_status(:ok)
+    expect(json.fetch('diff').map { _1.fetch('type') }.uniq).to eq(['context'])
+  end
+
+  ['タググループ:', 'tag_group:', 'TAG_GROUP:'].each do |prefix|
+    it "round trips #{ prefix } through create, lookup, search and update" do
+      post '/wiki', params: {
+          locale: 'ain-Kana', title: "#{ prefix }parent", body: '- tag_group:locale group' },
+          headers: headers
+      expect(response).to have_http_status(:created)
+      id = json.fetch('id')
+      expect(json.fetch('body')).to include('タググループ:locale group')
+      path = "/wiki/title/#{ CGI.escapeURIComponent("#{ prefix }parent") }"
+      get path, params: { locale: 'ain-Kana' }
+      expect(response).to have_http_status(:ok)
+      expect(json.fetch('id')).to eq(id)
+      get "#{ path }/exists", params: { locale: 'ain-Kana' }
+      expect(response).to have_http_status(:no_content)
+      get '/wiki/search', params: { locale: 'ain-Kana', title: "#{ prefix }parent" }
+      expect(json.map { _1.fetch('id') }).to eq([id])
+      put "/wiki/#{ id }", params: {
+          locale: 'ain-Kana', title: "#{ prefix }renamed", body: '- ainu_member' },
+          headers: headers
+      expect(response).to have_http_status(:ok)
+      get "/tag_groups/#{ id }", params: { locale: 'ain-Kana' }
+      expect(json.fetch('members').sole.fetch('tag').fetch('name')).to eq('ainu_member')
+    end
+  end
+
+  it 'resolves Markdown names in the requested language and rolls back invalid input' do
+    parsed = TagGroupMarkdownParser.parse(ainu_locale, body: '- ainu_member')
+    expect(parsed.fetch(:members)).to eq(members)
+    expect do
+      TagGroupMarkdownParser.parse(ainu_locale, body: '- japanese_member')
+    end.to raise_error(TagGroupMarkdownParser::InvalidDocument)
+    before_state = group_state
+    put "/wiki/#{ group.id }", params: {
+        locale: 'ain-Kana', title: 'タググループ:partial rename', body: '- japanese_member' },
+        headers: headers
+    expect(response).to have_http_status(:unprocessable_entity)
+    expect(group_state).to eq(before_state)
+  end
+
+  it 'passes locale into native validation and facade compatibility checks' do
+    post '/tag_groups', params: {
+        locale: 'ain-Kana', name: 'native', description: nil, members:, placements: },
+        headers:, as: :json
+    expect(response).to have_http_status(:created)
+    id = json.fetch('id')
+    expect(json.fetch('members').sole.fetch('tag').fetch('name')).to eq('ainu_member')
+    get "/wiki/#{ id }", params: { locale: 'ain-Kana' }
+    expect(response).to have_http_status(:ok)
+    body = json.fetch('body')
+    put "/wiki/#{ id }", params: { locale: 'ain-Kana', title: 'tag_group:native', body: },
+        headers: headers
+    expect(response).to have_http_status(:ok)
+    expect(TagGroup.find(id).version_no).to eq(1)
+  end
+
+  it 'does not substitute current or Japanese names for a missing historical language' do
+    other = create(:tag, primary_name: 'historical_japanese')
+    TagVersioning.ensure_snapshot!(other, created_by_user: user)
+    old_group = TagGroupOperation.create!(
+        Locale.nipponese, name: 'old group', description: nil,
+        members: [{ 'tag_id' => other.id }],
+        placements: [{ 'tag_id' => other.id, 'children' => [] }], actor: user)
+    add_ainu_name(other, 'current_ainu')
+    version = old_group.versions.sole
+    representation = TagGroupRepr.historical(ainu_locale, version)
+    expect(representation.fetch('members').sole.fetch('tag').fetch('name')).to be_nil
+    expect(representation.fetch('placements').sole.fetch('tag').fetch('name')).to be_nil
+    get "/wiki/#{ old_group.id }", params: { locale: 'ain-Kana', version: version.id }
+    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response.body).not_to include('historical_japanese', 'current_ainu')
+  end
+end

backend/spec/requests/tag_group_markdown_spec.rb

@@ -115,6 +115,15 @@ RSpec.describe 'Tag group Markdown round trips through the Wiki facade', type: :
         MARKDOWN
   end
 
+  it 'round trips a top-level list followed by heading Sections' do
+    check_round_trip(
+        members: [tag_member(series), tag_member(deer)],
+        placements: [tag_node(series),
+                     { 'section_name' => '区分', 'description' => nil,
+                       'children' => [tag_node(deer)] }],
+        markdown: "- ぼざろクリーチャーシリーズ\n\n## 区分\n\n- 洗澡鹿")
+  end
+
   it 'rejects mixed top-level heading Sections and Tags without losing structure' do
     id = seed_group(
         name: '混在構造', members: [tag_member(series)],

backend/spec/requests/tag_group_wiki_spec.rb

@@ -1,26 +1,24 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag group Wiki facade reads', type: :request do
+  include WikiRecords
   include TagGroupRecords
 
   let!(:user) { create_member_user! }
   let!(:old_tag) { group_tag('旧タグ') }
   let!(:new_tag) { group_tag('新タグ') }
-  let!(:page) { legacy_group('読取り契約', '- 旧タグ') }
-  let!(:first_revision) { page.current_revision }
+  let!(:page) { create_markdown_group('読取り契約', '- 旧タグ') }
+  let!(:first_revision) { page.versions.sole }
   let!(:last_revision) do
-    Wiki::Commit.legacy_content!(page:, body: '- 新タグ', created_user: user)
+    parsed = TagGroupMarkdownParser.parse(Locale.nipponese, body: '- 新タグ')
+    TagGroupOperation.update!(
+        Locale.nipponese,
+        group: page, name: page.name, actor: user,
+        **parsed.slice(:description, :members, :placements))
+    page.versions.order(:version_no).last
   end
 
-  before do
-    I18n.locale = :ja
-    migrate_groups
-    page.update_columns(body: 'legacy stale current')
-    page.wiki_revisions.each do |revision|
-      revision.wiki_lines.update_all(body: 'legacy stale revision')
-    end
-    page.wiki_versions.update_all(body: 'legacy stale version')
-  end
+  before { I18n.locale = :ja }
 
   [:id, :title].each do |lookup|
     context "with #{ lookup } lookup" do
@@ -69,35 +67,15 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
     end
   end
 
-  it 'combines Tag Groups, Help and Tag Descriptions in the unfiltered list' do
-    help = Wiki::Commit.create_legacy_content!(
-        tag_name: create(:tag_name, name: 'Help:混在'), body: 'help', created_by_user: user)
-    TagDescriptionOperation.create!(tag: new_tag, body: 'tag description', created_by_user: user)
+  it 'combines Tag Groups and Tag Descriptions without Help in the unfiltered list' do
+    TagDescriptionOperation.create!(
+        Locale.nipponese, tag: new_tag, body: 'tag description', created_by_user: user)
     get '/wiki'
     expect(response).to have_http_status(:ok)
     expect(json.map { _1.fetch('title') }).to include(
-        'タググループ:読取り契約', help.title, '新タグ')
+        'タググループ:読取り契約', '新タグ')
   end
 
-  it 'keeps Help readable when its ID collides with a new group' do
-    help = Wiki::Commit.create_legacy_content!(
-        tag_name: create(:tag_name, name: 'Help:ID重複'), body: 'help body',
-        created_by_user: user)
-    seed_group(name: '別 ID重複', id: help.id, description: 'group body')
-
-    get '/wiki'
-    expect(response).to have_http_status(:ok)
-    expect(json.map { _1.fetch('title') }).to include(help.title, 'タググループ:別 ID重複')
-
-    get "/wiki/title/#{ CGI.escapeURIComponent(help.title) }"
-    expect(response).to have_http_status(:ok)
-    expect(json.fetch('body')).to eq('help body')
-
-    get '/wiki/changes'
-    expect(response).to have_http_status(:ok)
-    expect(json.map { _1.dig('wiki_page', 'title') }).to include(
-        help.title, 'タググループ:別 ID重複')
-  end
 
   it 'finds groups by a partial prefix of their displayed title' do
     get '/wiki', params: { title: 'タググル' }
@@ -109,8 +87,10 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
   end
 
   it 'does not restore a stale namespaced Wiki page after a group rename' do
-    old_page = legacy_group('旧名称', '- 旧本文')
-    seed_group(name: '新名称', id: old_page.id, description: '正本')
+    group = create_markdown_group('旧名称', '正本')
+    TagGroupOperation.update!(
+        Locale.nipponese,
+        group:, name: '新名称', description: '正本', members: [], placements: [], actor: user)
 
     get group_title_path('旧名称')
     expect(response).to have_http_status(:not_found)
@@ -122,12 +102,9 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
   end
 
   it 'orders mixed resource history by timestamp rather than independent IDs' do
-    help = Wiki::Commit.create_legacy_content!(
-        tag_name: create(:tag_name, name: 'Help:時系列'), body: 'help',
-        created_by_user: user)
-    TagDescriptionOperation.create!(tag: new_tag, body: 'description', created_by_user: user)
+    TagDescriptionOperation.create!(
+        Locale.nipponese, tag: new_tag, body: 'description', created_by_user: user)
     TagGroupVersion.update_all(created_at: 3.days.ago)
-    WikiRevision.where(wiki_page_id: help.id).update_all(created_at: 2.days.ago)
     TagDescriptionVersion.update_all(created_at: 1.day.ago)
 
     get '/wiki/changes'
@@ -136,8 +113,7 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
     timestamps = json.map { Time.iso8601(_1.fetch('timestamp')) }
     expect(timestamps).to eq(timestamps.sort.reverse)
     titles = json.map { _1.dig('wiki_page', 'title') }
-    expect(titles.index('新タグ')).to be < titles.index(help.title)
-    expect(titles.index(help.title)).to be < titles.index('タググループ:読取り契約')
+    expect(titles.index('新タグ')).to be < titles.index('タググループ:読取り契約')
   end
 
   it 'renders nullable group editors without raising' do
@@ -166,19 +142,6 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
         'wiki_page' => include('id' => page.id, 'title' => 'タググループ:読取り契約'))
   end
 
-  it 'includes Help and group history but excludes legacy-only migrated revisions' do
-    extra = Wiki::Commit.legacy_content!(page:, body: 'legacy only', created_user: user)
-    help = Wiki::Commit.create_legacy_content!(
-        tag_name: create(:tag_name, name: 'Help:変更一覧'), body: 'help', created_by_user: user)
-    get '/wiki/changes'
-    expect(response).to have_http_status(:ok)
-    rows = json.select { _1.fetch('wiki_page').fetch('title') == 'タググループ:読取り契約' }
-    expect(rows.map { _1.fetch('revision_id') }).to eq([last_revision.id, first_revision.id])
-    expect(rows.map { _1.fetch('revision_id') }).not_to include(extra.id)
-    expect(json).to include(include(
-        'revision_id' => help.current_revision.id,
-        'wiki_page' => include('title' => help.title)))
-  end
 
   [false, true].each do |explicit|
     it "diffs structured snapshots with #{ explicit ? 'explicit' : 'current' } target" do
@@ -212,93 +175,5 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
     expect(json.fetch('body').strip).to eq('独立した説明')
   end
 
-  context 'when Help, description and group share the same numeric ID' do
-    let(:colliding_help) do
-      Wiki::Commit.create_legacy_content!(
-          tag_name: create(:tag_name, name: 'Help:三者ID衝突'),
-          body: 'help', created_by_user: user)
-    end
-    let(:colliding_group_id) do
-      seed_group(name: '三者ID衝突', id: colliding_help.id, description: 'group')
-    end
-    let(:colliding_description) do
-      TagDescription.create!(
-          id: colliding_help.id, tag: new_tag, language_code: 'ja',
-          body: 'description', version_no: 1)
-    end
-    let(:colliding_description_version) do
-      TagDescriptionVersion.create!(
-          tag_id: new_tag.id, language_code: 'ja', version_no: 1,
-          event_type: 'create', body: 'description', created_by_user_id: user.id,
-          created_at: Time.current)
-    end
 
-    before do
-      colliding_group_id
-      colliding_description
-      colliding_description_version
-    end
-
-    it 'lists all three resources without deduplicating their numeric ID' do
-      get '/wiki'
-
-      expect(response).to have_http_status(:ok)
-      rows = json.select { _1.fetch('id') == colliding_help.id }
-      expect(rows.map { [_1.fetch('id'), _1.fetch('title')] }).to contain_exactly(
-          [colliding_help.id, colliding_help.title],
-          [colliding_description.id, '新タグ'],
-          [colliding_group_id, 'タググループ:三者ID衝突'])
-    end
-
-    it 'lists each resource history without deduplicating the shared resource ID' do
-      get '/wiki/changes'
-
-      expect(response).to have_http_status(:ok)
-      rows = json.select { _1.fetch('wiki_page').fetch('id') == colliding_help.id }
-      histories = rows.map do |row|
-        [row.fetch('revision_id'), row.fetch('wiki_page').fetch('title')]
-      end
-      expect(histories).to contain_exactly(
-          [colliding_help.current_revision.id, colliding_help.title],
-          [colliding_description_version.id, '新タグ'],
-          [group_version(colliding_group_id, 1).fetch('id'), 'タググループ:三者ID衝突'])
-    end
-
-    it 'still excludes legacy copies of an actually migrated group and its history' do
-      extra = Wiki::Commit.legacy_content!(page:, body: 'legacy only', created_user: user)
-
-      get '/wiki'
-
-      expect(response).to have_http_status(:ok)
-      rows = json.select { _1.fetch('id') == page.id }
-      expect(rows.map { _1.fetch('title') }).to eq(['タググループ:読取り契約'])
-
-      get '/wiki/changes'
-
-      expect(response).to have_http_status(:ok)
-      rows = json.select { _1.fetch('wiki_page').fetch('id') == page.id }
-      expect(rows.map { _1.fetch('revision_id') })
-          .to contain_exactly(first_revision.id, last_revision.id)
-      expect(rows.map { _1.fetch('revision_id') }).not_to include(extra.id)
-      expect(rows.map { _1.fetch('wiki_page').fetch('title') })
-          .to all(eq('タググループ:読取り契約'))
-    end
-  end
-
-  it 'resolves colliding group, Help and description IDs by title' do
-    help = Wiki::Commit.create_legacy_content!(
-        tag_name: create(:tag_name, name: 'Help:ID衝突'), body: 'help', created_by_user: user)
-    seed_group(name: 'ID衝突', id: help.id, description: 'group')
-    TagDescription.create!(
-        id: help.id, tag: new_tag, language_code: 'ja', body: 'description', version_no: 1)
-    TagDescriptionVersion.create!(
-        tag_id: new_tag.id, language_code: 'ja', version_no: 1,
-        event_type: 'create', body: 'description', created_at: Time.current)
-    { 'タググループ:ID衝突' => 'group', 'Help:ID衝突' => 'help', '新タグ' => 'description' }
-        .each do |title, body|
-      get "/wiki/title/#{ CGI.escapeURIComponent(title) }"
-      expect(response).to have_http_status(:ok)
-      expect(json.fetch('body').strip).to eq(body)
-    end
-  end
 end

backend/spec/requests/tag_group_wiki_write_spec.rb

@@ -33,8 +33,10 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
     end
   end
 
-  it 'creates the group, first snapshot and compatibility Wiki history' do
-    create_group
+  it 'creates the group, snapshot and native version history' do
+    expect { create_group }
+        .to change(TagGroup, :count).by(1)
+        .and change(TagGroupVersion, :count).by(1)
     expect(response).to have_http_status(:created)
     group = group_rows('tag_groups', name: '新規').sole
     expect(json).to include('id' => group.fetch('id'), 'title' => 'タググループ:新規')
@@ -42,11 +44,9 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
     version = group_version(group.fetch('id'), 1)
     expect(version).to include('event_type' => 'create', 'created_by_user_id' => user.id)
     expect(group).to include('created_by_user_id' => user.id, 'updated_by_user_id' => user.id)
-    page = WikiPage.joins(:tag_name).find_by!(tag_names: { name: 'タググループ:新規' })
-    expect(page.body.strip).to eq('- 洗澡鹿')
-    expect(page.current_revision.body).to eq(page.body)
-    expect(page.wiki_versions.sole.body).to eq(page.body)
-    # New IDs are independently allocated; no global identity assertion here.
+    get group_title_path('新規')
+    expect(response).to have_http_status(:ok)
+    expect(json.fetch('body')).to eq('- 洗澡鹿')
   end
 
   it 'keeps repeated placements but only one membership and one snapshot member' do
@@ -106,10 +106,9 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
   end
 
   context 'updating a migrated group' do
-    let!(:page) { legacy_group('更新', '- 洗澡鹿') }
-    let!(:old_revision) { page.current_revision }
+    let!(:page) { create_markdown_group('更新', '- 洗澡鹿') }
+    let!(:old_revision) { page.versions.order(:version_no).last }
 
-    before { migrate_groups }
 
     def update_group body: '- 伊地知ニジカ', title: 'タググループ:更新', request_headers: headers
       put "/wiki/#{ page.id }", params: { title:, body: }, headers: request_headers
@@ -117,9 +116,9 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
 
     [1, 3].each do |repetitions|
       it "keeps identical Markdown unchanged after #{ repetitions } Wiki PUTs" do
-        body = page.body
+        body = group_markdown(page)
         travel_to(1.hour.from_now) do
-          expect_noop_group_update(group_id: page.id, page:) do
+          expect_noop_group_update(group_id: page.id) do
             repetitions.times do
               update_group(body:)
               expect(response).to have_http_status(:ok)
@@ -132,13 +131,13 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
     it 'keeps identical Markdown unchanged with a stale base_revision_id' do
       update_group
       expect(response).to have_http_status(:ok)
-      body = page.reload.body
-      expect(page.current_revision.id).not_to eq(old_revision.id)
+      body = group_markdown(page)
+      expect(page.versions.order(:version_no).last.id).not_to eq(old_revision.id)
 
       travel_to(1.hour.from_now) do
-        expect_noop_group_update(group_id: page.id, page:) do
+        expect_noop_group_update(group_id: page.id) do
           put "/wiki/#{ page.id }",
-              params: { title: page.title, body:, base_revision_id: old_revision.id },
+              params: { title: "タググループ:#{ page.name }", body:, base_revision_id: old_revision.id },
               headers: headers
         end
       end
@@ -146,9 +145,9 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
 
     it 'keeps the original editor on identical Markdown from another member' do
       editor = create(:user, :member)
-      body = page.body
+      body = group_markdown(page)
       travel_to(1.hour.from_now) do
-        expect_noop_group_update(group_id: page.id, page:) do
+        expect_noop_group_update(group_id: page.id) do
           update_group(body:, request_headers: { 'X-Transfer-Code' => editor.inheritance_code })
         end
       end
@@ -166,11 +165,11 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
           page.id, number: 2,
           members: [{ 'tag_id' => other_tag.id, 'version_no' => other_tag.version_no }],
           placements: changed_placements)
-      body = page.reload.body
+      body = group_markdown(page)
       expect(body).to eq('- 伊地知ニジカ')
 
       travel_to(1.hour.from_now) do
-        expect_noop_group_update(group_id: page.id, page:) { update_group(body:) }
+        expect_noop_group_update(group_id: page.id) { update_group(body:) }
       end
     end
 
@@ -185,16 +184,13 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
       expect(group_version(page.id, 1)).to eq(old)
       expect(group_version(page.id, 2)).to include(
           'event_type' => 'update', 'created_by_user_id' => user.id)
-      expect(page.reload.body.strip).to eq('- 伊地知ニジカ')
-      expect(page.wiki_revisions.count).to eq(2)
-      expect(page.wiki_versions.count).to eq(2)
-      expect(page.current_revision.body).to eq(page.body)
-      expect(page.wiki_versions.order(:version_no).last.body).to eq(page.body)
+      expect(group_markdown(page).strip).to eq('- 伊地知ニジカ')
+      expect(page.versions.count).to eq(2)
     end
 
     it 'accepts the current base_revision_id used by the existing frontend' do
       put "/wiki/#{ page.id }",
-          params: { title: page.title, body: '- 伊地知ニジカ',
+          params: { title: "タググループ:#{ page.name }", body: '- 伊地知ニジカ',
                     base_revision_id: old_revision.id }, headers: headers
       expect(response).to have_http_status(:ok)
       expect(group_rows('tag_groups', id: page.id).sole.fetch('version_no')).to eq(2)
@@ -205,12 +201,12 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
       expect(response).to have_http_status(:ok)
 
       put "/wiki/#{ page.id }",
-          params: { title: page.title, body: '- 洗澡鹿',
+          params: { title: "タググループ:#{ page.name }", body: '- 洗澡鹿',
                     base_revision_id: old_revision.id }, headers: headers
 
       expect(response).to have_http_status(:ok)
       expect(group_rows('tag_groups', id: page.id).sole.fetch('version_no')).to eq(3)
-      expect(page.reload.body.strip).to eq('- 洗澡鹿')
+      expect(group_markdown(page).strip).to eq('- 洗澡鹿')
     end
 
     it 'records the editor and update time' do
@@ -255,9 +251,7 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
       let!(:page) do
         next unless operation == :update
 
-        legacy = legacy_group('更新', '- 洗澡鹿')
-        seed_group(name: '更新', id: legacy.id, members:, placements:)
-        legacy
+        create_markdown_group('更新', '- 洗澡鹿')
       end
       let!(:child_id) { seed_group(name: '子グループ', description: '子') }
 
@@ -293,8 +287,8 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
         expect(group_state).to eq(before_state)
       end
 
-      (TagGroupRecords::GROUP_TABLES + ['wiki_pages', 'wiki_revisions', 'wiki_versions'])
-          .each do |table|
+      tables = TagGroupRecords::GROUP_TABLES
+      tables.each do |table|
         it "rolls back all writes after a real #{ table } write fails" do
           expect_atomic_group_write(table) { write_group(operation, headers) }
         end

backend/spec/requests/tag_group_write_integrity_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag group write integrity', type: :request do
+  include WikiRecords
   include TagGroupRecords
   include ActiveSupport::Testing::TimeHelpers
 
@@ -23,11 +24,6 @@ RSpec.describe 'Tag group write integrity', type: :request do
     put "/wiki/#{ id }", params: { title:, body:, base_revision_id: base }, headers: headers
   end
 
-  def create_help body
-    Wiki::Commit.create_legacy_content!(
-        tag_name: create(:tag_name, name: 'Help:既存'), body:, created_by_user: user)
-  end
-
   def expect_no_writes
     before_state = group_state
     yield
@@ -36,69 +32,31 @@ RSpec.describe 'Tag group write integrity', type: :request do
   end
 
   context 'resource identity' do
-    it 'rejects removing the prefix from a migrated group atomically' do
-      page = legacy_group('更新', '- 洗澡鹿')
-      seed_group(name: '更新', id: page.id, members:, placements:)
-
-      expect_no_writes do
-        put_wiki(page.id, title: '更新', base: page.current_revision.id)
-      end
-    end
 
     it 'rejects an unprefixed update to an independent group' do
       id = seed_group(name: '独立', members:, placements:)
       expect_no_writes { put_wiki(id, title: '独立') }
     end
 
-    it 'does not revive legacy writes when the compatibility title is stale' do
-      page = legacy_group('更新', '- 洗澡鹿')
-      seed_group(name: '更新', id: page.id, members:, placements:)
-      page.tag_name.update!(name: '古い別名')
 
-      expect_no_writes { put_wiki(page.id, title: '古い別名') }
-    end
-
-    it 'renames the group and its compatibility page through the operation' do
-      page = legacy_group('更新', '- 洗澡鹿')
-      seed_group(name: '更新', id: page.id, members:, placements:)
+    it 'renames the group and its facade title through the operation' do
+      page = create_markdown_group('更新', '- 洗澡鹿')
 
       put_wiki(page.id, title: 'タググループ:改名')
 
       expect(response).to have_http_status(:ok)
       expect(TagGroup.find(page.id)).to have_attributes(name: '改名', version_no: 2)
-      expect(page.reload.title).to eq('タググループ:改名')
-      expect(page.body).to eq('- 伊地知ニジカ')
+      expect("タググループ:#{ page.reload.name }").to eq('タググループ:改名')
+      expect(group_markdown(page)).to eq('- 伊地知ニジカ')
     end
 
-    it 'updates Help with a colliding group ID without altering the group' do
-      page = create_help('Help body')
-      id = seed_group(name: '別グループ', id: page.id, members:, placements:)
-      group_before = TagGroup.find(id).attributes
-      version_before = group_version(id, 1)
 
-      put_wiki(id, title: 'Help:改名', body: 'Help after')
-
-      expect(response).to have_http_status(:ok)
-      expect(page.reload.body).to eq('Help after')
-      expect(page.title).to eq('Help:改名')
-      expect(TagGroup.find(id).attributes).to eq(group_before)
-      expect(group_version(id, 1)).to eq(version_before)
-    end
-
-    it 'rejects an ambiguous unprefixed rename when Help and group IDs collide' do
-      page = create_help('Help body')
-      seed_group(name: '更新', id: page.id, members:, placements:)
-
-      expect_no_writes { put_wiki(page.id, title: '更新') }
-      expect_no_writes do
-        put_wiki(page.id, title: '更新', base: page.current_revision.id)
-      end
-    end
 
     it 'keeps a description update separate from a colliding group' do
-      page = Wiki::Commit.create_content!(
+      page = seed_description(
           tag_name: tag.tag_name('ja'), body: 'description before', created_by_user: user)
-      id = seed_group(name: '更新', id: page.id, members:, placements:)
+      description = TagDescription.find_by!(tag_id: tag.id)
+      id = seed_group(name: '更新', id: description.id, members:, placements:)
       group_before = TagGroup.find(id).attributes
 
       put_wiki(id, title: '洗澡鹿', body: 'description after')
@@ -109,105 +67,22 @@ RSpec.describe 'Tag group write integrity', type: :request do
       expect(TagGroup.find(id).attributes).to eq(group_before)
     end
 
-    it 'does not route a colliding Help write into an unrelated description' do
-      page = create_help('Help before')
-      id = seed_group(name: '更新', id: page.id, members:, placements:)
-      description = TagDescription.create!(
-          id:, tag:, language_code: 'ja', version_no: 1, body: 'description')
+  end
 
-      put_wiki(id, title: 'Help:既存', body: 'Help after')
 
-      expect(response).to have_http_status(:ok)
-      expect(page.reload.body).to eq('Help after')
-      expect(description.reload.body).to eq('description')
-      expect(TagGroup.find(id).version_no).to eq(1)
-      expect_no_writes { put_wiki(id, title: '洗澡鹿', body: 'description after') }
-      put_wiki(id, title: 'タググループ:更新')
-      expect(response).to have_http_status(:ok)
-      expect(TagGroup.find(id).version_no).to eq(2)
-      expect(page.reload.body).to eq('Help after')
-      expect(description.reload.body).to eq('description')
+  it 'rolls back a facade create when its saved structure cannot be rendered' do
+    allow(TagGroupMarkdownRenderer).to receive(:render)
+        .and_raise(TagGroupMarkdownRenderer::UnsupportedStructure, 'unsupported')
+    expect_no_writes do
+      post '/wiki', params: { title: 'タググループ:新規', body: '- 洗澡鹿' }, headers: headers
     end
   end
 
-  context 'compatibility synchronisation' do
-    it 'synchronises a native rename without modifying an ID-colliding Help page' do
-      help = create_help('Help before')
-      id = seed_group(name: '更新', id: help.id, members:, placements:)
-      help_before = help.attributes
-
-      put "/tag_groups/#{ id }", params: native_payload(name: '改名'), headers:, as: :json
-
-      expect(response).to have_http_status(:ok)
-      page = WikiPage.joins(:tag_name).find_by!(tag_names: { name: 'タググループ:改名' })
-      expect(page.id).not_to eq(help.id)
-      expect(page.body).to eq('- 洗澡鹿')
-      expect(page.current_revision.body).to eq(page.body)
-      expect(page.wiki_versions.sole.body).to eq(page.body)
-      expect(help.reload.attributes).to eq(help_before)
-    end
-
-    ['wiki_lines', 'wiki_revision_lines'].each do |table|
-      it "rolls back native and compatibility state on #{ table } failure" do
-        expect_atomic_group_write(table) do
-          post '/tag_groups', params: native_payload, headers:, as: :json
-        end
-      end
-    end
-
-    it 'rolls back a renderer failure instead of treating it as unsupported structure' do
-      allow(TagGroupMarkdownRenderer).to receive(:render).and_raise('renderer failure')
-      before_state = group_state
-
-      expect do
-        post '/tag_groups', params: native_payload, headers:, as: :json
-      end.to raise_error(RuntimeError, 'renderer failure')
-
-      expect(group_state).to eq(before_state)
-    end
-
-    it 'preserves unplaced membership and reports the skipped sync with its version' do
-      page = legacy_group('更新', '- 洗澡鹿')
-      id = seed_group(name: '更新', id: page.id, members:, placements:)
-      wiki_before = group_state.slice(*TagGroupRecords::WRITE_TABLES.drop(5))
-      warnings = []
-      allow(Rails.logger).to receive(:warn) { warnings << _1 }
-
-      put "/tag_groups/#{ id }",
-          params: native_payload(member_rows: members + [{ 'tag_id' => other_tag.id }]),
-          headers:, as: :json
-
-      expect(response).to have_http_status(:ok)
-      expect(json.fetch('members').map { _1.fetch('tag').fetch('id') })
-          .to contain_exactly(tag.id, other_tag.id)
-      expect(group_version(id, 2).fetch('members')).to include(
-          { 'tag_id' => other_tag.id, 'version_no' => other_tag.version_no })
-      expect(group_state.slice(*TagGroupRecords::WRITE_TABLES.drop(5))).to eq(wiki_before)
-      payload = JSON.parse(warnings.grep(/tag_group_wiki_sync_skipped/).sole.split(' ', 2).last)
-      expect(payload).to include(
-          'status' => 'unsupported_structure', 'tag_group_id' => id,
-          'version_no' => 2, 'user_id' => user.id,
-          'reason' => '掲載位置のない membership は Markdown にできません．')
-    end
-
-    it 'preserves a list Section description and records why no Wiki was created' do
-      nodes = [{ 'tag_id' => tag.id, 'children' => [
-          { 'section_name' => '区分', 'description' => '構造化の説明', 'children' => [] }] }]
-      warnings = []
-      allow(Rails.logger).to receive(:warn) { warnings << _1 }
-      before_count = WikiPage.count
-
-      post '/tag_groups', params: native_payload(nodes:), headers:, as: :json
-
-      expect(response).to have_http_status(:created)
-      id = json.fetch('id')
-      expect(group_version(id, 1).fetch('placements')).to eq(nodes)
-      expect(json.fetch('placements').sole.fetch('children').sole)
-          .to include('description' => '構造化の説明')
-      expect(WikiPage.count).to eq(before_count)
-      expect(warnings.grep(/tag_group_wiki_sync_skipped/).sole)
-          .to include('リスト内 Section の説明文は Markdown にできません．')
-    end
+  it 'rolls back a facade update when its saved structure cannot be rendered' do
+    id = seed_group(name: '更新', members:, placements:)
+    allow(TagGroupMarkdownRenderer).to receive(:render)
+        .and_raise(TagGroupMarkdownRenderer::UnsupportedStructure, 'unsupported')
+    expect_no_writes { put_wiki(id, title: 'タググループ:改名') }
   end
 
   context 'identifier Markdown' do
@@ -291,10 +166,10 @@ RSpec.describe 'Tag group write integrity', type: :request do
       expect(group_version(id, 2)).to include('description' => '説明を追加', 'members' => members)
     end
 
-    it 'rolls back membership removal and placement edits on a late sync failure' do
+    it 'rolls back membership removal and placement edits on a version persistence failure' do
       new_members = [{ 'tag_id' => tag.id }]
       new_nodes = [{ 'tag_id' => tag.id, 'children' => [] }]
-      expect_atomic_group_write('wiki_versions') do
+      expect_atomic_group_write('tag_group_versions') do
         put "/tag_groups/#{ id }",
             params: native_payload(nodes: new_nodes, member_rows: new_members), headers:, as: :json
       end

backend/spec/requests/tag_groups_spec.rb

@@ -234,8 +234,7 @@ RSpec.describe 'Tag group native API', type: :request do
 
     context 'compatibility writes for representable structures' do
       let(:group_id) do
-        page = legacy_group('専用API', '説明')
-        seed_group(name: '専用API', id: page.id, description: '説明')
+        seed_group(name: '専用API', description: '説明')
       end
       let(:members) { [{ 'tag_id' => tag.id }, { 'tag_group_id' => child_id }] }
       let(:snapshot_members) do
@@ -252,10 +251,9 @@ RSpec.describe 'Tag group native API', type: :request do
             group_id, number: 2, description: '全体の説明', placements:,
             members: snapshot_members + [
                 { 'tag_id' => unplaced.id, 'version_no' => unplaced.version_no }])
-        page = WikiPage.joins(:tag_name).find_by!(tag_names: { name: 'タググループ:専用API' })
 
         travel_to(1.hour.from_now) do
-          expect_noop_group_update(group_id:, page:) do
+          expect_noop_group_update(group_id:) do
             native_write(:update, unplaced_payload)
           end
         end
@@ -267,20 +265,18 @@ RSpec.describe 'Tag group native API', type: :request do
             members: [{ 'tag_id' => tag.id }, { 'tag_group_id' => child_id }], placements: }
         end
         let(:additional_tag) { group_tag('追加対象タグ') }
-        let(:compatibility_page) do
-          WikiPage.joins(:tag_name).find_by!(tag_names: { name: 'タググループ:構造化' })
-        end
 
         before do
           native_write(:update, synchronised_payload)
           expect(response).to have_http_status(:ok)
-          expect(compatibility_page.body).to include('- 掲載タグ', '- タググループ:子')
+          expect(group_markdown(TagGroup.find(group_id)))
+              .to include('- 掲載タグ', '- タググループ:子')
         end
 
         [1, 3].each do |repetitions|
           it "keeps identical native content unchanged after #{ repetitions } PUTs" do
             travel_to(1.hour.from_now) do
-              expect_noop_group_update(group_id:, page: compatibility_page) do
+              expect_noop_group_update(group_id:) do
                 repetitions.times do
                   native_write(:update, synchronised_payload)
                   expect(response).to have_http_status(:ok)
@@ -292,7 +288,7 @@ RSpec.describe 'Tag group native API', type: :request do
 
         it 'treats membership order alone as a no-op' do
           travel_to(1.hour.from_now) do
-            expect_noop_group_update(group_id:, page: compatibility_page) do
+            expect_noop_group_update(group_id:) do
               native_write(:update, synchronised_payload.merge(
                   members: synchronised_payload.fetch(:members).reverse))
             end
@@ -302,7 +298,7 @@ RSpec.describe 'Tag group native API', type: :request do
         it 'keeps the original editor when another member submits identical content' do
           editor = create(:user, :member)
           travel_to(1.hour.from_now) do
-            expect_noop_group_update(group_id:, page: compatibility_page) do
+            expect_noop_group_update(group_id:) do
               put "/tag_groups/#{ group_id }", params: synchronised_payload,
                   headers: { 'X-Transfer-Code' => editor.inheritance_code }, as: :json
             end
@@ -313,7 +309,7 @@ RSpec.describe 'Tag group native API', type: :request do
           put "/wiki/#{ group_id }",
               params: { title: 'タググループ:構造化', body: '- 未掲載タグ' }, headers: headers
           expect(response).to have_http_status(:ok)
-          expect(compatibility_page.reload.body).to eq('- 未掲載タグ')
+          expect(group_markdown(TagGroup.find(group_id))).to eq('- 未掲載タグ')
           same_content = {
               name: '構造化', description: nil, members: [{ 'tag_id' => unplaced.id }],
               placements: [{ 'tag_id' => unplaced.id, 'children' => [] }] }
@@ -323,7 +319,7 @@ RSpec.describe 'Tag group native API', type: :request do
               placements: same_content.fetch(:placements))
 
           travel_to(1.hour.from_now) do
-            expect_noop_group_update(group_id:, page: compatibility_page) do
+            expect_noop_group_update(group_id:) do
               native_write(:update, same_content)
             end
           end
@@ -332,7 +328,7 @@ RSpec.describe 'Tag group native API', type: :request do
         ['name', 'description', 'membership addition', 'membership removal',
          'Section name', 'Section description', 'placement order', 'placement hierarchy']
             .each do |change|
-          it "records a real #{ change } change in both histories" do
+          it "records a real #{ change } change in native history" do
             changed = synchronised_payload.deep_dup
             section = changed.fetch(:placements).first
             children = section.fetch('children')
@@ -356,11 +352,6 @@ RSpec.describe 'Tag group native API', type: :request do
             old_versions = group_rows('tag_group_versions', tag_group_id: group_id)
             group = TagGroup.find(group_id)
             number = group.version_no
-            page = compatibility_page
-            old_revision_id = page.current_revision.id
-            old_wiki_version_id = page.wiki_versions.order(version_no: :desc).first.id
-            revision_count = page.wiki_revisions.count
-            version_count = page.wiki_versions.count
             travel_to(1.hour.from_now) { native_write(:update, changed) }
 
             expect(response).to have_http_status(:ok)
@@ -379,18 +370,23 @@ RSpec.describe 'Tag group native API', type: :request do
             versions = group_rows('tag_group_versions', tag_group_id: group_id)
             expect(versions.size).to eq(old_versions.size + 1)
             expect(versions.select { _1.fetch('version_no') <= number }).to eq(old_versions)
-            expect(page.wiki_revisions.count).to eq(revision_count + 1)
-            expect(page.wiki_versions.count).to eq(version_count + 1)
-            expect(page.reload.current_revision.id).not_to eq(old_revision_id)
-            expect(page.wiki_versions.order(version_no: :desc).first.id)
-                .not_to eq(old_wiki_version_id)
             get group_title_path(changed.fetch(:name))
             expect(response).to have_http_status(:ok)
-            expect(json.fetch('body')).to eq(page.body)
+            expect(json.fetch('body')).to eq(group_markdown(group))
           end
         end
       end
 
+      it 'creates native state and its native history' do
+        expect { native_write(:create) }
+            .to change(TagGroup, :count).by(1)
+            .and change(TagGroupVersion, :count).by(1)
+        expect(response).to have_http_status(:created)
+        expect_group_snapshot(
+            json.fetch('id'), number: 1, members: snapshot_members,
+            placements:, description: '全体の説明')
+      end
+
       [:create, :update].each do |operation|
         it "synchronises Wiki current state and histories on native #{ operation }" do
           native_write(operation)
@@ -399,18 +395,13 @@ RSpec.describe 'Tag group native API', type: :request do
           number = operation == :create ? 1 : 2
           expect_group_snapshot(
               id, number:, members: snapshot_members, placements:, description: '全体の説明')
-          page = WikiPage.joins(:tag_name).find_by!(tag_names: { name: 'タググループ:構造化' })
-          expect(page.body).to include('全体の説明', '# 区分', '- 掲載タグ', '- タググループ:子')
-          expect(page.current_revision.body).to eq(page.body)
-          expect(page.wiki_versions.order(:version_no).last.body).to eq(page.body)
-          expect(page.wiki_revisions.count).to eq(number)
-          expect(page.wiki_versions.count).to eq(number)
+          expect(TagGroup.find(id).versions.count).to eq(number)
           get group_title_path('構造化')
           expect(response).to have_http_status(:ok)
-          expect(json.fetch('body')).to eq(page.body)
+          expect(json.fetch('body')).to include('全体の説明', '# 区分', '- 掲載タグ')
         end
 
-        (TagGroupRecords::GROUP_TABLES + ['wiki_pages', 'wiki_revisions', 'wiki_versions'])
+        TagGroupRecords::GROUP_TABLES
             .each do |table|
           it "rolls back native #{ operation } after #{ table } writes" do
             expect_atomic_group_write(table) { native_write(operation) }
@@ -418,19 +409,18 @@ RSpec.describe 'Tag group native API', type: :request do
         end
       end
 
-      it 'uses AUTO_INCREMENT for a new group instead of supplying a compatibility ID' do
-        inserts = []
-        subscriber = lambda do |*args|
-          sql = args.last.fetch(:sql)
-          inserts << sql if sql.match?(/\A\s*INSERT INTO `?tag_groups`?\s/i)
-        end
-        ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') do
-          native_write(:create)
-        end
+      it 'assigns the next group ID above the existing maximum' do
+        child_id
+        expected_id = [TagGroup.maximum(:id).to_i, TagDescription.maximum(:id).to_i].max + 1
+        native_write(:create)
         expect(response).to have_http_status(:created)
-        expect(inserts.size).to eq(1)
-        columns = inserts.sole[/\((.*?)\)/, 1].split(',').map { _1.strip.delete('`') }
-        expect(columns).not_to include('id')
+        expect(json.fetch('id')).to be >= expected_id
+      end
+
+      TagGroupRecords::GROUP_TABLES.each do |table|
+        it "rolls back native creation after #{ table } writes" do
+          expect_atomic_group_write(table) { native_write(:create) }
+        end
       end
 
       it 'updates a native group through Wiki and then reads structured current data' do

backend/spec/requests/tag_resource_ids_spec.rb

@@ -0,0 +1,61 @@
+require 'rails_helper'
+
+RSpec.describe 'Tag resource ID allocation', type: :request do
+  include WikiRecords
+  let!(:user) { create_member_user! }
+  let(:headers) { { 'X-Transfer-Code' => user.inheritance_code } }
+
+  def create_description name
+    tag = create(:tag, primary_name: name)
+    post '/wiki', params: { title: tag.name('ja'), body: 'description' }, headers: headers
+    expect(response).to have_http_status(:created)
+    TagDescription.find(json.fetch('id'))
+  end
+
+  def create_group name
+    post '/tag_groups', params: { name:, members: [], placements: [] }, headers:, as: :json
+    expect(response).to have_http_status(:created)
+    TagGroup.find(json.fetch('id'))
+  end
+
+  it 'shares resource and revision IDs while keeping independent version numbers' do
+    description = create_description('first')
+    group = create_group('second')
+    other = create_description('third')
+    expect([description.id, group.id, other.id]).to eq(
+        [description.id, group.id, other.id].sort.uniq)
+    versions = [current_description_version(description), group.versions.sole,
+                current_description_version(other)]
+    expect(versions.map(&:id)).to eq(versions.map(&:id).sort.uniq)
+    expect(versions.map(&:version_no)).to eq([1, 1, 1])
+    [description, group, other].zip(versions).each do |resource, version|
+      get "/wiki/#{ resource.id }"
+      expect(response).to have_http_status(:ok)
+      expect(json.fetch('revision_id')).to eq(version.id)
+    end
+  end
+
+  it 'does not reuse a deleted description ID for a group or vice versa' do
+    description = create_description('deleted')
+    description.destroy!
+    group = create_group('deleted group')
+    expect(group.id).to be > description.id
+    group.destroy!
+    expect(create_description('replacement').id).to be > group.id
+  end
+
+  it 'preserves resource and old revision identity on an update' do
+    description = create_description('stable')
+    original_resource_id = description.id
+    original = current_description_version(description)
+    snapshot = original.attributes
+    put "/wiki/#{ description.id }",
+        params: { title: 'stable', body: 'after', base_revision_id: original.id },
+        headers: headers
+    expect(response).to have_http_status(:ok)
+    expect(description.reload.id).to eq(original_resource_id)
+    expect(description.reload).to have_attributes(body: 'after', version_no: 2)
+    expect(original.reload.attributes).to eq(snapshot)
+    expect(current_description_version(description).id).to be > original.id
+  end
+end

backend/spec/requests/tag_versions_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'TagVersions API', type: :request do
+  include WikiRecords
   let(:member) { create(:user, :member, name: 'version member') }
 
   let!(:tag) { create(:tag, primary_name: 'tag_versions_target', category: :general) }
@@ -240,18 +241,19 @@ RSpec.describe 'TagVersions API', type: :request do
       wiki_tag = create(:tag, primary_tag_name: wiki_tag_name, category: :general)
 
       wiki_page =
-          Wiki::Commit.create_content!(
+          seed_description(
               tag_name: wiki_tag_name,
               body: 'before',
               created_by_user: member,
               message: 'init')
 
-      Wiki::Commit.content!(
-          page: wiki_page,
+      TagDescriptionOperation.update!(
+        Locale.nipponese,
+          tag: wiki_page.tag,
           body: 'after',
-          created_user: member,
+          updated_by_user: member,
           message: 'edit',
-          base_revision_id: wiki_page.current_revision.id)
+          base_revision_id: current_description_version(wiki_page).id)
 
       get '/tags/versions', params: { id: wiki_tag.id }
 

backend/spec/requests/tag_wiki_history_integrity_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag and wiki history integrity', type: :request do
+  include WikiRecords
   let(:member_user) { create(:user, role: 'member') }
 
   def stub_current_user user
@@ -13,7 +14,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
   end
 
   def create_wiki_for_tag! tag:, body: 'wiki body', user: member_user
-    Wiki::Commit.create_content!(
+    seed_description(
         tag_name: primary_tag_name_for(tag, 'ja'),
         body:,
         created_by_user: user,
@@ -28,7 +29,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
     it 'renames the current Wiki resource without adding body history' do
       tag = create_tag!(name: 'patch_tag_wiki_before')
       wiki_page = create_wiki_for_tag!(tag:, body: 'wiki body before')
-      wiki_history = wiki_page.wiki_versions.map(&:attributes)
+      wiki_history = description_versions(wiki_page).map(&:attributes)
 
       expect {
         patch "/tags/#{ tag.id }", params: {
@@ -36,7 +37,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
         }
       }
           .to change(TagVersion, :count).by(2)
-          .and change(WikiVersion, :count).by(0)
+          .and change(TagDescriptionVersion, :count).by(0)
 
       expect(response).to have_http_status(:ok)
 
@@ -44,16 +45,16 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
       wiki_page.reload
 
       expect(primary_tag_name_for(tag, 'ja').name).to eq('patch_tag_wiki_after')
-      expect(wiki_page.title).to eq('patch_tag_wiki_after')
+      expect(wiki_page.tag.name('ja')).to eq('patch_tag_wiki_after')
 
-      expect(wiki_page.wiki_versions.reload.map(&:attributes)).to eq(wiki_history)
+      expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
     end
 
     it 'does not record wiki_version when only category changes' do
       tag = create_tag!(name: 'patch_tag_category_only')
       wiki_page = create_wiki_for_tag!(tag:, body: 'wiki body before')
 
-      before_wiki_versions = wiki_page.wiki_versions.count
+      before_wiki_versions = description_versions(wiki_page).count
 
       expect {
         patch "/tags/#{ tag.id }", params: {
@@ -69,7 +70,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
 
       expect(primary_tag_name_for(tag, 'ja').name).to eq('patch_tag_category_only')
       expect(tag.category).to eq('meme')
-      expect(wiki_page.wiki_versions.count).to eq(before_wiki_versions)
+      expect(description_versions(wiki_page).count).to eq(before_wiki_versions)
     end
   end
 
@@ -77,7 +78,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
     it 'renames the current Wiki resource without adding body history' do
       tag = create_tag!(name: 'put_tag_wiki_before')
       wiki_page = create_wiki_for_tag!(tag:, body: 'wiki body before')
-      wiki_history = wiki_page.wiki_versions.map(&:attributes)
+      wiki_history = description_versions(wiki_page).map(&:attributes)
 
       expect {
         put "/tags/#{ tag.id }", params: {
@@ -89,7 +90,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
         }
       }
           .to change(TagVersion, :count).by(2)
-          .and change(WikiVersion, :count).by(0)
+          .and change(TagDescriptionVersion, :count).by(0)
 
       expect(response).to have_http_status(:ok)
 
@@ -97,16 +98,16 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
       wiki_page.reload
 
       expect(primary_tag_name_for(tag, 'ja').name).to eq('put_tag_wiki_after')
-      expect(wiki_page.title).to eq('put_tag_wiki_after')
+      expect(wiki_page.tag.name('ja')).to eq('put_tag_wiki_after')
 
-      expect(wiki_page.wiki_versions.reload.map(&:attributes)).to eq(wiki_history)
+      expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
     end
 
     it 'does not record wiki_version when only category changes' do
       tag = create_tag!(name: 'put_tag_category_only')
       wiki_page = create_wiki_for_tag!(tag:, body: 'wiki body before')
 
-      before_wiki_versions = wiki_page.wiki_versions.count
+      before_wiki_versions = description_versions(wiki_page).count
 
       expect {
         put "/tags/#{ tag.id }", params: {
@@ -126,14 +127,14 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
 
       expect(primary_tag_name_for(tag, 'ja').name).to eq('put_tag_category_only')
       expect(tag.category).to eq('meme')
-      expect(wiki_page.wiki_versions.count).to eq(before_wiki_versions)
+      expect(description_versions(wiki_page).count).to eq(before_wiki_versions)
     end
 
     it 'does not record wiki_version when only aliases change' do
       tag = create_tag!(name: 'put_tag_alias_only')
       wiki_page = create_wiki_for_tag!(tag:, body: 'wiki body before')
 
-      before_wiki_versions = wiki_page.wiki_versions.count
+      before_wiki_versions = description_versions(wiki_page).count
 
       expect {
         put "/tags/#{ tag.id }", params: {
@@ -147,7 +148,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
           .to change(TagVersion, :count).by(2)
 
       expect(response).to have_http_status(:ok)
-      expect(wiki_page.reload.wiki_versions.count).to eq(before_wiki_versions)
+      expect(description_versions(wiki_page).count).to eq(before_wiki_versions)
     end
   end
 end

backend/spec/requests/tags_spec.rb

@@ -2,6 +2,7 @@ require 'cgi'
 require 'rails_helper'
 
 RSpec.describe 'Tags API', type: :request do
+  include WikiRecords
   let!(:tn) { create(:tag_name, name: 'spec_tag') }
   let!(:tag) { create(:tag, primary_tag_name: tn, category: :general) }
   let!(:alias_tn) { create(:tag_name, :alias, name: 'unko', tag:) }
@@ -38,6 +39,22 @@ RSpec.describe 'Tags API', type: :request do
   end
 
   describe 'GET /tags' do
+    it 'serialises descriptions and parents without loading legacy Wiki pages' do
+      TagDescription.create!(tag:, language_code: 'ja', body: '', version_no: 1)
+      TagDescription.create!(tag: tag2, language_code: 'ja', body: '', version_no: 1)
+      TagImplication.create!(tag:, parent_tag: tag2)
+      queries = []
+      subscriber = ->(*args) { queries << args.last.fetch(:sql) }
+      ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') do
+        get '/tags', params: { name: 'spec_tag' }
+      end
+      expect(response).to have_http_status(:ok)
+      row = response_tags.sole
+      expect(row.fetch('has_wiki')).to be(true)
+      expect(row.fetch('parents').sole.fetch('has_wiki')).to be(true)
+      expect(queries.grep(/\bSELECT\b.*\bwiki_(pages|revisions|versions)\b/im)).to be_empty
+    end
+
     it 'includes legacy external JSON alongside an internal tag with the same id' do
       external = create(:external_tag, id: tag.id, name: 'spec_external', post_count: 3)
 
@@ -729,13 +746,13 @@ RSpec.describe 'Tags API', type: :request do
 
       it 'PATCH の名称変更で Wiki の本文履歴を追加しない' do
         wiki_page =
-            Wiki::Commit.create_content!(
+            seed_description(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'wiki body before',
                 created_by_user: member_user,
                 message: 'init')
 
-        wiki_history = wiki_page.wiki_versions.map(&:attributes)
+        wiki_history = description_versions(wiki_page).map(&:attributes)
 
         expect {
           patch "/tags/#{ tag.id }", params: {
@@ -743,23 +760,23 @@ RSpec.describe 'Tags API', type: :request do
           }
         }
             .to change(TagVersion, :count).by(2)
-            .and change(WikiVersion, :count).by(0)
+            .and change(TagDescriptionVersion, :count).by(0)
 
         expect(response).to have_http_status(:ok)
 
-        expect(wiki_page.reload.title).to eq('patch_wiki_renamed_tag')
-        expect(wiki_page.wiki_versions.reload.map(&:attributes)).to eq(wiki_history)
+        expect(wiki_page.reload.tag.name('ja')).to eq('patch_wiki_renamed_tag')
+        expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
       end
 
       it 'tag の category だけを変更しても wiki version は作成しない' do
         wiki_page =
-            Wiki::Commit.create_content!(
+            seed_description(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'wiki body before',
                 created_by_user: member_user,
                 message: 'init')
 
-        before_wiki_version_count = wiki_page.reload.wiki_versions.count
+        before_wiki_version_count = description_versions(wiki_page).count
 
         expect {
           patch "/tags/#{ tag.id }", params: {
@@ -768,7 +785,7 @@ RSpec.describe 'Tags API', type: :request do
         }.to change(TagVersion, :count).by(2)
 
         expect(response).to have_http_status(:ok)
-        expect(wiki_page.reload.wiki_versions.count).to eq(before_wiki_version_count)
+        expect(description_versions(wiki_page).count).to eq(before_wiki_version_count)
       end
 
       it 'full update で旧名 alias が残った tag を PATCH で旧名へ戻せる' do
@@ -799,7 +816,7 @@ RSpec.describe 'Tags API', type: :request do
 
       it '別 tag の正規名には変更できない' do
         wiki_page =
-            Wiki::Commit.create_content!(
+            seed_description(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'patch collision wiki',
                 created_by_user: member_user,
@@ -815,7 +832,7 @@ RSpec.describe 'Tags API', type: :request do
         expect(primary_tag_name_for(tag.reload, 'ja').name).to eq('spec_tag')
         expect(TagName.where(tag_id: tag.id, language_code: 'ja', primary_flg: false).pluck(:name))
             .to contain_exactly('unko')
-        expect(wiki_page.reload.tag_name).to eq(primary_tag_name_for(tag, 'ja'))
+        expect(wiki_page.reload.tag.tag_name('ja')).to eq(primary_tag_name_for(tag, 'ja'))
       end
 
       it 'system tag の name は変更できない' do
@@ -1193,7 +1210,7 @@ RSpec.describe 'Tags API', type: :request do
         expect(old_name_alias).to have_attributes(
             tag_id: tag.id, language_code: 'ja', primary_flg: false)
 
-        expect(alias_tn.reload.tag_id).to be_nil
+        expect(TagName.exists?(alias_tn.id)).to be(false)
 
         expect(TagName.where(tag_id: tag.parents.select(:id),
                              language_code: 'ja', primary_flg: true).pluck(:name))
@@ -1378,20 +1395,17 @@ RSpec.describe 'Tags API', type: :request do
 
       it 'Wiki を持つ Tag の名称変更で本文履歴を追加しない' do
         wiki_page =
-            Wiki::Commit.create_content!(
+            seed_description(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'wiki body before',
                 created_by_user: member_user,
                 message: 'init')
 
-        Wiki::Commit.content!(
-          page: wiki_page,
-          body: 'wiki body before',
-          created_user: member_user,
-          message: 'init'
-        )
+        TagDescriptionOperation.update!(
+            Locale.nipponese, tag: wiki_page.tag, body: 'wiki body before',
+            updated_by_user: member_user, message: 'init')
 
-        wiki_history = wiki_page.wiki_versions.map(&:attributes)
+        wiki_history = description_versions(wiki_page).map(&:attributes)
 
         expect {
           put "/tags/#{ tag.id }", params: {
@@ -1403,22 +1417,22 @@ RSpec.describe 'Tags API', type: :request do
           }
         }
             .to change(TagVersion, :count).by(2)
-            .and change(WikiVersion, :count).by(0)
+            .and change(TagDescriptionVersion, :count).by(0)
 
         expect(response).to have_http_status(:ok)
 
-        expect(wiki_page.reload.title).to eq('put_wiki_version_tag')
-        expect(wiki_page.wiki_versions.reload.map(&:attributes)).to eq(wiki_history)
+        expect(wiki_page.reload.tag.name('ja')).to eq('put_wiki_version_tag')
+        expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
       end
 
       it 'wiki を持つ tag を旧 alias へ戻しても wiki を新しい正本名へ移す' do
         wiki_page =
-            Wiki::Commit.create_content!(
+            seed_description(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'wiki body before',
                 created_by_user: member_user,
                 message: 'init')
-        wiki_history = wiki_page.wiki_versions.map(&:attributes)
+        wiki_history = description_versions(wiki_page).map(&:attributes)
 
         expect {
           put "/tags/#{ tag.id }", params: {
@@ -1438,20 +1452,19 @@ RSpec.describe 'Tags API', type: :request do
           }
         }
             .to change(TagVersion, :count).by(3)
-            .and change(WikiVersion, :count).by(0)
+            .and change(TagDescriptionVersion, :count).by(0)
 
         expect(response).to have_http_status(:ok)
 
         tag.reload
 
-        expect(wiki_page.reload.tag_name).to eq(primary_tag_name_for(tag, 'ja'))
-        expect(TagName.find_by!(language_code: 'ja', name: 'put_wiki_roundtrip_b').wiki_page)
-            .to be_nil
+        expect(wiki_page.reload.tag.tag_name('ja')).to eq(primary_tag_name_for(tag, 'ja'))
+        expect(wiki_page.reload.tag_id).to eq(tag.id)
         expect(TagName.find_by!(language_code: 'ja', name: 'put_wiki_roundtrip_b'))
             .to have_attributes(tag_id: tag.id, primary_flg: false)
 
-        expect(wiki_page.title).to eq('spec_tag')
-        expect(wiki_page.wiki_versions.reload.map(&:attributes)).to eq(wiki_history)
+        expect(wiki_page.tag.name('ja')).to eq('spec_tag')
+        expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
       end
 
       it '別名を他 tag から奪った場合、奪はれた側の tag version も作成する' do
@@ -1504,7 +1517,7 @@ RSpec.describe 'Tags API', type: :request do
             name: 'put_alias_collision_name',
             tag: old_owner)
         wiki_page =
-            Wiki::Commit.create_content!(
+            seed_description(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'put collision wiki',
                 created_by_user: member_user,
@@ -1538,7 +1551,7 @@ RSpec.describe 'Tags API', type: :request do
         expect(old_owner_versions.last.event_type).to eq('update')
         expect(version_alias_names(old_owner_versions.last, 'ja'))
             .not_to include('put_alias_collision_name')
-        expect(wiki_page.reload.tag_name).to eq(primary_tag_name_for(tag, 'ja'))
+        expect(wiki_page.reload.tag.tag_name('ja')).to eq(primary_tag_name_for(tag, 'ja'))
       end
 
       it 'parent_tags に指定すると循環する tag は 422 にする' do
@@ -1563,13 +1576,13 @@ RSpec.describe 'Tags API', type: :request do
 
       it 'Tag の名称変更で Wiki の本文履歴を追加しない' do
         wiki_page =
-            Wiki::Commit.create_content!(
+            seed_description(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'wiki body before',
                 created_by_user: member_user,
                 message: 'init')
 
-        wiki_history = wiki_page.wiki_versions.map(&:attributes)
+        wiki_history = description_versions(wiki_page).map(&:attributes)
 
         expect {
           put "/tags/#{ tag.id }", params: {
@@ -1581,12 +1594,12 @@ RSpec.describe 'Tags API', type: :request do
           }
         }
             .to change(TagVersion, :count).by(2)
-            .and change(WikiVersion, :count).by(0)
+            .and change(TagDescriptionVersion, :count).by(0)
 
         expect(response).to have_http_status(:ok)
 
-        expect(wiki_page.reload.title).to eq('put_wiki_renamed_tag')
-        expect(wiki_page.wiki_versions.reload.map(&:attributes)).to eq(wiki_history)
+        expect(wiki_page.reload.tag.name('ja')).to eq('put_wiki_renamed_tag')
+        expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
       end
     end
   end

backend/spec/requests/wiki_conflict_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Wiki conflict handling', type: :request do
+  include WikiRecords
   let!(:user) { create_member_user! }
 
   def auth_headers user
@@ -9,34 +10,33 @@ RSpec.describe 'Wiki conflict handling', type: :request do
 
   it 'returns 409 when base_revision_id is stale' do
     page =
-        Wiki::Commit.create_content!(
-            tag_name: create(:tag_name, name: 'wiki_conflict_request'),
+        seed_description(
+            tag_name: create(:tag, primary_name: 'wiki_conflict_request').tag_name('ja'),
             body: 'first',
             created_by_user: user,
             message: 'init')
 
-    stale_id = page.current_revision.id
+    stale_id = current_description_version(page).id
 
-    Wiki::Commit.content!(
-        page:,
+    TagDescriptionOperation.update!(
+        Locale.nipponese,
+        tag: page.tag,
         body: 'second',
-        created_user: user,
+        updated_by_user: user,
         message: 'other edit',
         base_revision_id: stale_id)
 
     put "/wiki/#{ page.id }",
-        params: {
-          title: 'wiki_conflict_request',
-          body: 'third',
-          message: 'stale',
-          base_revision_id: stale_id,
-        },
+        params: { title: 'wiki_conflict_request',
+                  body: 'third',
+                  message: 'stale',
+                  base_revision_id: stale_id },
         headers: auth_headers(user)
 
     expect(response).to have_http_status(:conflict)
 
     page.reload
     expect(page.body).to eq('second')
-    expect(page.current_revision.message).to eq('other edit')
+    expect(current_description_version(page)).to have_attributes(body: 'second', version_no: 2)
   end
 end

backend/spec/requests/wiki_creation_freeze_spec.rb

@@ -0,0 +1,47 @@
+require 'rails_helper'
+
+RSpec.describe 'Wiki creation freeze', type: :request do
+  include TagGroupRecords
+  include WikiRecords
+
+  let!(:user) { create_member_user! }
+  let(:headers) { { 'X-Transfer-Code' => user.inheritance_code } }
+
+
+  context 'existing description write protection' do
+    let!(:tag) { create(:tag, primary_name: 'protected_description') }
+    let!(:page) do
+      seed_description(tag_name: tag.tag_name('ja'), body: 'before', created_by_user: user)
+    end
+
+    [nil, :guest, :banned].each do |role|
+      it "rejects #{ role || 'anonymous' } without changing either history" do
+        actor = role && create(:user, role == :banned ? :member : role)
+        actor.update!(banned_at: Time.current) if role == :banned
+        request_headers = actor ? { 'X-Transfer-Code' => actor.inheritance_code } : { }
+        before_state = group_state
+        put "/wiki/#{ page.id }", params: { title: tag.name('ja'), body: 'after' },
+            headers: request_headers
+        expect(response).to have_http_status(role ? :forbidden : :unauthorized)
+        expect(group_state).to eq(before_state)
+      end
+    end
+
+    it 'rejects banned IPs without writes' do
+      IpAddress.create!(ip_address: IPAddr.new('127.0.0.1').hton, banned_at: Time.current)
+      before_state = group_state
+      put "/wiki/#{ page.id }", params: { title: tag.name('ja'), body: 'after' }, headers: headers
+      expect(response).to have_http_status(:forbidden)
+      expect(group_state).to eq(before_state)
+    end
+
+    ['', "\r\n\r\n"].each do |body|
+      it "rejects invalid description body #{ body.inspect } atomically" do
+        before_state = group_state
+        put "/wiki/#{ page.id }", params: { title: tag.name('ja'), body: }, headers: headers
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(group_state).to eq(before_state)
+      end
+    end
+  end
+end

backend/spec/requests/wiki_history_integrity_spec.rb

@@ -1,198 +0,0 @@
-require 'cgi'
-require 'rails_helper'
-
-RSpec.describe 'Wiki history integrity', type: :request do
-  let!(:user) { create_member_user! }
-
-  def auth_headers user
-    { 'X-Transfer-Code' => user.inheritance_code }
-  end
-
-  def create_wiki_page title:, body: 'body', message: 'init', user: self.user
-    Wiki::Commit.create_content!(
-        tag_name: create(:tag_name, name: title),
-        body:,
-        created_by_user: user,
-        message:)
-  end
-
-  describe 'POST /wiki' do
-    it 'creates wiki_page, wiki_revision, and wiki_version atomically' do
-      expect {
-        post '/wiki',
-             params: {
-               title: 'Help:wiki_history_create_atomic',
-               body: "a\nb\nc",
-               message: 'initial commit',
-             },
-             headers: auth_headers(user)
-      }
-          .to change(WikiPage, :count).by(1)
-          .and change(WikiRevision, :count).by(1)
-          .and change(WikiVersion, :count).by(1)
-
-      expect(response).to have_http_status(:created)
-
-      page = WikiPage.find(json.fetch('id'))
-      revision = page.current_revision
-      version = page.wiki_versions.order(:version_no).last
-
-      expect(page.title).to eq('Help:wiki_history_create_atomic')
-      expect(page.body).to eq("a\nb\nc")
-
-      expect(revision).to be_content
-      expect(revision.message).to eq('initial commit')
-      expect(revision.lines_count).to eq(3)
-
-      expect(version).to have_attributes(
-        version_no: 1,
-        event_type: 'create',
-        title: 'Help:wiki_history_create_atomic',
-        body: "a\nb\nc",
-        reason: 'initial commit',
-        created_by_user_id: user.id
-      )
-    end
-
-    it 'returns 422 and creates nothing when normalised body is blank' do
-      expect {
-        post '/wiki',
-             params: {
-               title: 'Help:wiki_history_blank_body',
-               body: "\r\n\r\n",
-               message: 'blank',
-             },
-             headers: auth_headers(user)
-      }
-          .not_to change(WikiPage, :count)
-
-      expect(response).to have_http_status(:unprocessable_entity)
-      expect(WikiPage.joins(:tag_name)
-          .where(tag_names: { name: 'Help:wiki_history_blank_body' })).not_to exist
-    end
-
-    it 'returns 422 and creates no partial page when title already exists' do
-      create_wiki_page(title: 'Help:wiki_history_duplicate_title', body: 'first')
-
-      expect {
-        post '/wiki',
-             params: {
-               title: 'Help:wiki_history_duplicate_title',
-               body: 'second',
-               message: 'duplicate',
-             },
-             headers: auth_headers(user)
-      }
-          .not_to change(WikiPage, :count)
-
-      expect(response).to have_http_status(:unprocessable_entity)
-      expect(WikiPage.joins(:tag_name)
-          .where(tag_names: { name: 'Help:wiki_history_duplicate_title' }).count).to eq(1)
-    end
-  end
-
-  describe 'PUT /wiki/:id' do
-    it 'updates body and records wiki_revision and wiki_version' do
-      page = create_wiki_page(title: 'wiki_history_update_body', body: 'before')
-      current_id = page.current_revision.id
-
-      expect {
-        put "/wiki/#{ page.id }",
-            params: {
-              title: 'wiki_history_update_body',
-              body: 'after',
-              message: 'edit body',
-              base_revision_id: current_id,
-            },
-            headers: auth_headers(user)
-      }
-          .to change(WikiRevision, :count).by(1)
-          .and change(WikiVersion, :count).by(1)
-
-      expect(response).to have_http_status(:ok)
-
-      page.reload
-      version = page.wiki_versions.order(:version_no).last
-
-      expect(page.title).to eq('wiki_history_update_body')
-      expect(page.body).to eq('after')
-
-      expect(version).to have_attributes(
-        event_type: 'update',
-        title: 'wiki_history_update_body',
-        body: 'after',
-        reason: 'edit body',
-        created_by_user_id: user.id
-      )
-    end
-
-    it 'renames title and records wiki_version with new title' do
-      page = create_wiki_page(title: 'wiki_history_rename_before', body: 'before')
-      current_id = page.current_revision.id
-
-      expect {
-        put "/wiki/#{ page.id }",
-            params: {
-              title: 'wiki_history_rename_after',
-              body: 'after',
-              message: 'rename',
-              base_revision_id: current_id,
-            },
-            headers: auth_headers(user)
-      }
-          .to change(WikiRevision, :count).by(1)
-          .and change(WikiVersion, :count).by(1)
-
-      expect(response).to have_http_status(:ok)
-
-      page.reload
-      version = page.wiki_versions.order(:version_no).last
-
-      expect(page.title).to eq('wiki_history_rename_after')
-      expect(page.body).to eq('after')
-
-      expect(version).to have_attributes(
-        event_type: 'update',
-        title: 'wiki_history_rename_after',
-        body: 'after',
-        reason: 'rename',
-        created_by_user_id: user.id
-      )
-    end
-
-    it 'does not change title, body, revision, or version on stale base_revision_id' do
-      page = create_wiki_page(title: 'wiki_history_conflict_page', body: 'first')
-      stale_id = page.current_revision.id
-
-      Wiki::Commit.content!(
-          page:,
-          body: 'second',
-          created_user: user,
-          message: 'other edit',
-          base_revision_id: stale_id)
-
-      page.reload
-      current_title = page.title
-      current_body = page.body
-      revision_count = page.wiki_revisions.count
-      version_count = page.wiki_versions.count
-
-      put "/wiki/#{ page.id }",
-          params: {
-            title: 'wiki_history_conflict_renamed',
-            body: 'third',
-            message: 'stale edit',
-            base_revision_id: stale_id,
-          },
-          headers: auth_headers(user)
-
-      expect(response).to have_http_status(:conflict)
-
-      page.reload
-      expect(page.title).to eq(current_title)
-      expect(page.body).to eq(current_body)
-      expect(page.wiki_revisions.count).to eq(revision_count)
-      expect(page.wiki_versions.count).to eq(version_count)
-    end
-  end
-end

backend/spec/requests/wiki_index_order_spec.rb

@@ -0,0 +1,42 @@
+require 'rails_helper'
+
+RSpec.describe 'Wiki resource ordering', type: :request do
+  include TagGroupRecords
+  let(:user) { create_member_user! }
+
+  it 'selects the latest twenty across both resources before applying the global limit' do
+    start = Time.utc(2026, 1, 1)
+    descriptions = 24.times.map do |index|
+      tag = create(:tag, primary_name: "rank_#{ index }")
+      TagDescription.create!(tag:, language_code: 'ja', body: 'current', version_no: 1,
+                             updated_at: start + index.hours)
+    end
+    groups = [24, 25].map do |hour|
+      group = TagGroup.find(seed_group(name: "rank_group_#{ hour }"))
+      group.update_columns(updated_at: start + hour.hours)
+      group
+    end
+
+    get '/wiki', params: { title: 'rank' }
+
+    expect(response).to have_http_status(:ok)
+    expected = groups.reverse.map { ['tag_group', _1.id] } +
+        descriptions.last(18).reverse.map { ['tag_description', _1.id] }
+    expect(json.map { [_1.fetch('resource_type'), _1.fetch('id')] }).to eq(expected)
+  end
+
+  it 'breaks timestamp ties by resource kind and ID while retaining legacy overlaps' do
+    time = Time.utc(2026, 1, 1)
+    tag = create(:tag, primary_name: 'tied')
+    description = TagDescription.create!(tag:, language_code: 'ja', body: 'current',
+                           version_no: 1, updated_at: time)
+    group = TagGroup.find(seed_group(name: 'tied', id: description.id))
+    group.update_columns(updated_at: time)
+
+    2.times do
+      get '/wiki', params: { title: 'tied' }
+      expect(json.map { [_1.fetch('resource_type'), _1.fetch('id')] })
+          .to eq([['tag_description', description.id], ['tag_group', description.id]])
+    end
+  end
+end

backend/spec/requests/wiki_locale_spec.rb

@@ -0,0 +1,158 @@
+require 'rails_helper'
+
+RSpec.describe 'Wiki and native API locale contracts', type: :request do
+  include WikiRecords
+  include TagGroupRecords
+  include_context 'Ainu locale contract'
+
+  let!(:user) { create_member_user! }
+  let!(:tag) { create(:tag, primary_name: 'japanese_title') }
+  let!(:ainu_name) { add_ainu_name(tag, 'ainu_title') }
+  let(:headers) { { 'X-Transfer-Code' => user.inheritance_code } }
+  let!(:japanese) do
+    TagDescriptionOperation.create!(
+        Locale.nipponese, tag:, body: 'Japanese body', created_by_user: user)
+  end
+  let!(:ainu) do
+    TagDescriptionOperation.create!(
+        ainu_locale, tag:, body: 'Ainu body', created_by_user: user)
+  end
+
+  ['/wiki', '/wiki/search'].each do |path|
+    it "filters #{ path } by the selected language" do
+      get path, params: { locale: 'ain-Kana' }
+      expect(response).to have_http_status(:ok)
+      expect(json.map { _1.fetch('id') }).to eq([ainu.id])
+      expect(json.sole).to include('title' => 'ainu_title', 'body' => 'Ainu body')
+
+      get path, params: { locale: 'ain-Kana', title: 'japanese' }
+      expect(response).to have_http_status(:ok)
+      expect(json).to eq([])
+    end
+  end
+
+  it 'uses the existing default locale when no locale is specified' do
+    get '/wiki'
+    expect(response).to have_http_status(:ok)
+    expect(json.map { _1.fetch('id') }).to eq([japanese.id])
+  end
+
+  it 'resolves titles and aliases only in the selected language in both APIs' do
+    ['/wiki/title/japanese_title', '/tags/name/japanese_title/description'].each do |path|
+      get path, params: { locale: 'ain-Kana' }
+      expect(response).to have_http_status(:not_found)
+    end
+    ['/wiki/title/ainu_title', '/tags/name/ainu_title/description'].each do |path|
+      get path, params: { locale: 'ain-Kana' }
+      expect(response).to have_http_status(:ok)
+      expect(json.fetch('body')).to eq('Ainu body')
+    end
+    get '/wiki/title/ainu_title/exists', params: { locale: 'ain-Kana' }
+    expect(response).to have_http_status(:no_content)
+    get '/wiki/title/japanese_title/exists', params: { locale: 'ain-Kana' }
+    expect(response).to have_http_status(:not_found)
+  end
+
+  it 'does not disclose another language through ID, existence, diff or history' do
+    revision = current_description_version(japanese)
+    ["/wiki/#{ japanese.id }", "/wiki/#{ japanese.id }/exists",
+     "/wiki/#{ japanese.id }/diff"].each do |path|
+      get path, params: { locale: 'ain-Kana', from: revision.id }
+      expect(response).to have_http_status(:not_found)
+      expect(response.body).not_to include('Japanese body')
+    end
+    get '/wiki/changes', params: { locale: 'ain-Kana', id: japanese.id }
+    expect(response).to have_http_status(:ok)
+    expect(json).to eq([])
+    get '/wiki/changes', params: { locale: 'ain-Kana' }
+    expect(json.map { _1.fetch('revision_id') })
+        .to eq([current_description_version(ainu).id])
+  end
+
+  it 'does not update a description addressed through another language ID' do
+    snapshot = [japanese.attributes, ainu.attributes, ainu_name.attributes]
+    expect do
+      put "/wiki/#{ japanese.id }", params: {
+          locale: 'ain-Kana', title: 'renamed', body: 'wrong target' }, headers: headers
+    end.not_to change(TagDescriptionVersion, :count)
+    expect(response).to have_http_status(:not_found)
+    expect([japanese.reload.attributes, ainu.reload.attributes, ainu_name.reload.attributes])
+        .to eq(snapshot)
+  end
+
+  [:wiki, :native].each do |api|
+    it "creates the selected language through #{ api } without changing Japanese history" do
+      other = create(:tag, primary_name: 'other_japanese')
+      add_ainu_name(other, 'other_ainu')
+      original = TagDescriptionOperation.create!(
+          Locale.nipponese, tag: other, body: 'original', created_by_user: user)
+      snapshot = original.attributes
+      expect do
+        if api == :wiki
+          post '/wiki', params: { locale: 'ain-Kana', title: 'other_ainu', body: 'created' },
+               headers: headers
+        else
+          put "/tags/#{ other.id }/description", params: { locale: 'ain-Kana', body: 'created' },
+              headers: headers
+        end
+      end.to change(TagDescription, :count).by(1)
+          .and change(TagDescriptionVersion, :count).by(1)
+      expect(response).to have_http_status(:created)
+      created = TagDescription.find_by!(tag: other, language_code: 'ain')
+      expect(created).to have_attributes(body: 'created', version_no: 1)
+      expect(current_description_version(created)).to have_attributes(language_code: 'ain')
+      expect(original.reload.attributes).to eq(snapshot)
+    end
+  end
+
+  it 'shares selected-language edits and revision identity across both APIs' do
+    snapshot = japanese.attributes
+    first = current_description_version(ainu)
+    put "/tags/#{ tag.id }/description", params: { locale: 'ain-Kana', body: 'native edit' },
+        headers: headers
+    expect(response).to have_http_status(:ok)
+    second = current_description_version(ainu)
+    expect(second).to have_attributes(language_code: 'ain', version_no: 2)
+    expect(second.id).not_to eq(first.id)
+    get "/wiki/#{ ainu.id }", params: { locale: 'ain-Kana' }
+    expect(json).to include('body' => 'native edit', 'revision_id' => second.id)
+
+    put "/wiki/#{ ainu.id }", params: {
+        locale: 'ain-Kana', title: 'ainu_title', body: 'facade edit',
+        base_revision_id: second.id }, headers: headers
+    expect(response).to have_http_status(:ok)
+    get "/tags/#{ tag.id }/description", params: { locale: 'ain-Kana' }
+    expect(json).to include('body' => 'facade edit', 'language_code' => 'ain', 'version_no' => 3)
+    expect(japanese.reload.attributes).to eq(snapshot)
+  end
+
+  it 'rejects a stale selected-language revision without a partial title or body edit' do
+    stale = current_description_version(ainu)
+    TagDescriptionOperation.update!(
+        ainu_locale, tag:, body: 'current', updated_by_user: user)
+    snapshot = [ainu.reload.attributes, ainu_name.attributes, japanese.attributes]
+    expect do
+      put "/wiki/#{ ainu.id }", params: {
+          locale: 'ain-Kana', title: 'conflicting_name', body: 'current',
+          base_revision_id: stale.id }, headers: headers
+    end.to change(TagDescriptionVersion, :count).by(0).and change(TagVersion, :count).by(0)
+    expect(response).to have_http_status(:conflict)
+    expect([ainu.reload.attributes, ainu_name.reload.attributes, japanese.reload.attributes])
+        .to eq(snapshot)
+  end
+
+  it 'scopes historical show and diff to the selected description' do
+    first = current_description_version(ainu)
+    TagDescriptionOperation.update!(
+        ainu_locale, tag:, body: 'later', updated_by_user: user)
+    get "/wiki/#{ ainu.id }", params: { locale: 'ain-Kana', version: first.id }
+    expect(response).to have_http_status(:ok)
+    expect(json).to include('body' => 'Ainu body', 'revision_id' => first.id)
+    get "/wiki/#{ ainu.id }/diff", params: { locale: 'ain-Kana', from: first.id }
+    expect(response).to have_http_status(:ok)
+    expect(json.fetch('newer_revision_id')).to eq(current_description_version(ainu).id)
+    get "/wiki/#{ ainu.id }/diff", params: {
+        locale: 'ain-Kana', from: current_description_version(japanese).id }
+    expect(response).to have_http_status(:not_found)
+  end
+end

backend/spec/requests/wiki_spec.rb

@@ -4,6 +4,7 @@ require 'securerandom'
 
 
 RSpec.describe 'Wiki API', type: :request do
+  include WikiRecords
   def auth_headers(user)
     { 'X-Transfer-Code' => user.inheritance_code }
   end
@@ -18,7 +19,7 @@ RSpec.describe 'Wiki API', type: :request do
         deprecated_at: Time.zone.local(2026, 6, 1))
   end
   let!(:page) do
-    Wiki::Commit.create_content!(
+    seed_description(
         tag_name: tn,
         body: 'init',
         created_by_user: user,
@@ -108,94 +109,14 @@ RSpec.describe 'Wiki API', type: :request do
       end
     end
 
-    context 'when success' do
-      it 'creates wiki_page and first content revision' do
+    ['Help:TestPage', 'ヘルプ:ホーム'].each do |title|
+      it "rejects frozen creation of #{ title } without history writes" do
         expect do
-          post endpoint, params: { title: 'Help:TestPage', body: "a\nb\nc", message: 'init' },
-                         headers: auth_headers(member)
-        end
-            .to change(WikiPage, :count).by(1)
-            .and change(WikiRevision, :count).by(1)
-            .and change(WikiVersion, :count).by(1)
+          post endpoint, params: { title:, body: 'initial' }, headers: auth_headers(member)
+        end.to change(TagDescription, :count).by(0)
+            .and change(TagDescriptionVersion, :count).by(0)
 
-        expect(response).to have_http_status(:created)
-
-        page_id = json.fetch('id')
-        expect(json.fetch('title')).to eq('Help:TestPage')
-
-        created_page = WikiPage.find(page_id)
-        version = created_page.wiki_versions.order(:version_no).last
-
-        expect(version).to have_attributes(
-          version_no: 1,
-          event_type: 'create',
-          title: 'Help:TestPage',
-          body: "a\nb\nc",
-          created_by_user_id: member.id
-        )
-
-        rev = created_page.current_revision
-        expect(rev).to be_present
-        expect(rev).to be_content
-        expect(rev.message).to eq('init')
-
-        expect(created_page.body).to eq("a\nb\nc")
-
-        expect(rev.lines_count).to eq(3)
-        expect(rev.wiki_revision_lines.order(:position).pluck(:position)).to eq([0, 1, 2])
-        expect(rev.wiki_lines.pluck(:body)).to match_array(['a', 'b', 'c'])
-      end
-
-      it 'reuses existing WikiLine rows by sha256' do
-        # 先に同じ行を作っておく
-        WikiLine.create!(sha256: Digest::SHA256.hexdigest('a'), body: 'a', created_at: Time.current, updated_at: Time.current)
-
-        post endpoint,
-             params: { title: 'Help:Reuse', body: "a\na" },
-             headers: auth_headers(member)
-
-        page = WikiPage.find(JSON.parse(response.body).fetch('id'))
-        rev = page.current_revision
-        expect(rev.lines_count).to eq(2)
-
-        # "a" の WikiLine が増殖しない（1行のはず）
-        expect(WikiLine.where(body: 'a').count).to eq(1)
-      end
-
-      it 'deduplicates duplicated new lines before upsert' do
-        duplicated = 'duplicated_line_for_wiki_line_upsert_spec'
-
-        post endpoint,
-             params: { title: 'Help:DuplicateNewLine', body: "#{ duplicated }\n#{ duplicated }" },
-             headers: auth_headers(member)
-
-        expect(response).to have_http_status(:created)
-
-        page = WikiPage.find(json.fetch('id'))
-        rev = page.current_revision
-
-        expect(rev.lines_count).to eq(2)
-        expect(WikiLine.where(body: duplicated).count).to eq(1)
-        expect(rev.wiki_revision_lines.count).to eq(2)
-        expect(rev.wiki_revision_lines.pluck(:wiki_line_id).uniq.size).to eq(1)
-      end
-
-      it 'normalises CRLF and strips trailing newlines' do
-        post endpoint,
-             params: { title: 'Help:NormalisedBody',
-                       body: "a\r\nb\r\n\r\n", message: 'normalise' },
-             headers: auth_headers(member)
-
-        expect(response).to have_http_status(:created)
-
-        page = WikiPage.find(json.fetch('id'))
-        rev = page.current_revision
-        version = page.wiki_versions.order(:version_no).last
-
-        expect(page.body).to eq("a\nb")
-        expect(version.body).to eq("a\nb")
-        expect(rev.lines_count).to eq(2)
-        expect(rev.wiki_lines.order('wiki_revision_lines.position').map(&:body)).to eq(['a', 'b'])
+        expect(response.status).to be_between(400, 499)
       end
     end
   end
@@ -208,10 +129,10 @@ RSpec.describe 'Wiki API', type: :request do
       { 'X-Transfer-Code' => user.inheritance_code }
     end
 
-    let!(:test_tag_name) { create(:tag_name, name: 'TestPage') }
+    let!(:test_tag_name) { create(:tag, primary_name: 'TestPage').tag_name('ja') }
 
     let!(:page) do
-      Wiki::Commit.create_content!(
+      seed_description(
           tag_name: test_tag_name,
           body: "a\nb",
           created_by_user: member,
@@ -245,33 +166,30 @@ RSpec.describe 'Wiki API', type: :request do
 
     context 'when success' do
       it 'creates new revision and returns 200' do
-        current_id = page.wiki_revisions.maximum(:id)
+        current_id = description_versions(page).maximum(:id)
 
         expect do
           put "/wiki/#{page.id}",
-              params: { title: 'TestPage', body: "x\ny", message: 'edit', base_revision_id: current_id },
+              params: { title: 'TestPage', body: "x\ny", message: 'edit',
+                        base_revision_id: current_id },
               headers: auth_headers(member)
         end
-            .to change(WikiRevision, :count).by(1)
-            .and change(WikiVersion, :count).by(1)
+            .to change(TagDescriptionVersion, :count).by(1)
 
-        version = page.wiki_versions.order(:version_no).last
+
+        version = description_versions(page).order(:version_no).last
 
         expect(version).to have_attributes(
           event_type: 'update',
-          title: 'TestPage',
           body: "x\ny",
-          created_by_user_id: member.id
-        )
+          created_by_user_id: member.id)
 
         expect(response).to have_http_status(:ok)
 
         page.reload
-        rev = page.current_revision
-        expect(rev).to be_content
-        expect(rev.message).to eq('edit')
+        rev = current_description_version(page)
         expect(page.body).to eq("x\ny")
-        expect(rev.base_revision_id).to eq(current_id)
+        expect(rev.version_no).to eq(2)
       end
 
       it 'wiki body だけを変更しても tag version は作成しない' do
@@ -284,13 +202,13 @@ RSpec.describe 'Wiki API', type: :request do
             created_by_user: member)
 
         linked_page =
-            Wiki::Commit.create_content!(
+            seed_description(
                 tag_name: linked_tag_name,
                 body: 'before',
                 created_by_user: member,
                 message: 'init')
 
-        current_id = linked_page.current_revision.id
+        current_id = current_description_version(linked_page).id
         before_count = linked_tag.reload.tag_versions.count
 
         expect {
@@ -303,8 +221,8 @@ RSpec.describe 'Wiki API', type: :request do
               },
               headers: auth_headers(member)
         }
-            .to change(WikiRevision, :count).by(1)
-            .and change(WikiVersion, :count).by(1)
+            .to change(TagDescriptionVersion, :count).by(1)
+
 
         expect(response).to have_http_status(:ok)
         expect(linked_tag.reload.tag_versions.count).to eq(before_count)
@@ -314,10 +232,12 @@ RSpec.describe 'Wiki API', type: :request do
     context 'when conflict' do
       it 'returns 409 when base_revision_id mismatches' do
         # 先に別ユーザ（同じ member でもOK）が 1 回更新して先頭を進める
-        Wiki::Commit.content!(page: page, body: "zzz", created_user: member, message: 'other edit')
+        TagDescriptionOperation.update!(
+            Locale.nipponese, tag: page.tag, body: 'zzz',
+            updated_by_user: member, message: 'other edit')
         page.reload
 
-        stale_id = page.wiki_revisions.order(:id).first.id # わざと古い id
+        stale_id = description_versions(page).order(:id).first.id # わざと古い id
         put "/wiki/#{page.id}",
             params: { title: 'TestPage', body: 'x', base_revision_id: stale_id },
             headers: auth_headers(member)
@@ -358,13 +278,14 @@ RSpec.describe 'Wiki API', type: :request do
 
   describe 'GET /wiki/search' do
     before do
-      Wiki::Commit.create_content!(
-          tag_name: create(:tag_name, name: 'spec_wiki_title_2'),
+      search_tag = create(:tag, primary_name: 'spec_wiki_title_2')
+      seed_description(
+          tag_name: search_tag.tag_name('ja'),
           body: 'search body 2',
           created_by_user: user,
           message: 'init')
 
-      Wiki::Commit.create_content!(
+      seed_description(
           tag_name: create(:tag_name, name: 'unrelated_title'),
           body: 'unrelated body',
           created_by_user: user,
@@ -395,13 +316,15 @@ RSpec.describe 'Wiki API', type: :request do
 
   describe 'GET /wiki/changes' do
     let!(:rev1) do
-      Wiki::Commit.content!(page: page, body: "a\nb", created_user: user, message: 'r1')
-      page.current_revision
+      TagDescriptionOperation.update!(
+          Locale.nipponese, tag: page.tag, body: "a\nb", updated_by_user: user, message: 'r1')
+      current_description_version(page)
     end
 
     let!(:rev2) do
-      Wiki::Commit.content!(page: page, body: "a\nc", created_user: user, message: 'r2')
-      page.current_revision
+      TagDescriptionOperation.update!(
+          Locale.nipponese, tag: page.tag, body: "a\nc", updated_by_user: user, message: 'r2')
+      current_description_version(page)
     end
 
     it 'returns latest revisions (optionally filtered by page id)' do
@@ -435,12 +358,9 @@ RSpec.describe 'Wiki API', type: :request do
     it 'returns empty array when page has no revisions and filtered by id' do
       # 別ページを作って revision 無し
       tn2 = create(:tag_name, name: 'spec_no_rev')
-      # 異常データ: revision 無し WikiPage を直接作る
-      p2 = WikiPage.create!(
-          tag_name: tn2,
-          body: 'init',
-          created_user: user,
-          updated_user: user)
+      # 異常データ: Version のない TagDescription を直接作る
+      p2 = TagDescription.create!(
+          tag: tn2.tag, language_code: 'ja', body: 'init', version_no: 1)
 
       get "/wiki/changes?id=#{p2.id}"
       expect(response).to have_http_status(:ok)
@@ -476,13 +396,15 @@ RSpec.describe 'Wiki API', type: :request do
 
   describe 'GET /wiki/:id/diff' do
     let!(:rev_a) do
-      Wiki::Commit.content!(page: page, body: "a\nb\nc", created_user: user, message: 'A')
-      page.current_revision
+      TagDescriptionOperation.update!(
+          Locale.nipponese, tag: page.tag, body: "a\nb\nc", updated_by_user: user, message: 'A')
+      current_description_version(page)
     end
 
     let!(:rev_b) do
-      Wiki::Commit.content!(page: page, body: "a\nx\nc", created_user: user, message: 'B')
-      page.current_revision
+      TagDescriptionOperation.update!(
+          Locale.nipponese, tag: page.tag, body: "a\nx\nc", updated_by_user: user, message: 'B')
+      current_description_version(page)
     end
 
     it 'returns diff json between revisions' do
@@ -508,44 +430,23 @@ RSpec.describe 'Wiki API', type: :request do
 
       expect(response).to have_http_status(:ok)
       expect(json['older_revision_id']).to eq(rev_a.id)
-      expect(json['newer_revision_id']).to eq(page.current_revision.id)
+      expect(json['newer_revision_id']).to eq(current_description_version(page).id)
     end
   end
 
-  describe 'Wiki::Commit.redirect!' do
-    it 'raises because redirect revisions are deprecated' do
-      target_tag_name = create(:tag_name, name: 'redirect_deprecated_target')
-      target =
-          Wiki::Commit.create_content!(
-              tag_name: target_tag_name,
-              body: 'target',
-              created_by_user: user,
-              message: 'init')
-
-      expect {
-        Wiki::Commit.redirect!(
-          page: page,
-          redirect_page: target,
-          created_user: user,
-          message: 'redirect',
-          base_revision_id: page.current_revision.id
-        )
-      }.to raise_error(RuntimeError, '廃止しました．')
-    end
-  end
 
   it 'wiki title を変更すると対応する tag の version を作成する' do
     linked_tag_name = create(:tag_name, name: 'wiki_linked_tag_for_version')
     linked_tag = create(:tag, primary_tag_name: linked_tag_name, category: :general)
 
     linked_page =
-        Wiki::Commit.create_content!(
+        seed_description(
             tag_name: linked_tag_name,
             body: 'before',
             created_by_user: user,
             message: 'init')
 
-    current_id = linked_page.current_revision.id
+    current_id = current_description_version(linked_page).id
 
     expect {
       put "/wiki/#{ linked_page.id }",
@@ -557,8 +458,7 @@ RSpec.describe 'Wiki API', type: :request do
           },
           headers: auth_headers(user)
     }
-        .to change(WikiRevision, :count).by(1)
-        .and change(WikiVersion, :count).by(1)
+        .to change(TagDescriptionVersion, :count).by(1)
         .and change { linked_tag.reload.tag_versions.count }.by(2)
 
     expect(response).to have_http_status(:ok)

backend/spec/requests/wiki_title_collision_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Wiki title collision', type: :request do
+  include WikiRecords
   let!(:user) { create_member_user! }
 
   def auth_headers user
@@ -8,7 +9,7 @@ RSpec.describe 'Wiki title collision', type: :request do
   end
 
   def create_wiki_page title:, body:
-    Wiki::Commit.create_content!(
+    seed_description(
         tag_name: create(:tag_name, name: title),
         body:,
         created_by_user: user,
@@ -19,9 +20,9 @@ RSpec.describe 'Wiki title collision', type: :request do
     source = create_wiki_page(title: 'wiki_collision_source', body: 'source body')
     create_wiki_page(title: 'wiki_collision_target', body: 'target body')
 
-    source_revision_count = source.wiki_revisions.count
-    source_version_count = source.wiki_versions.count
-    old_title = source.title
+    source_revision_count = description_versions(source).count
+    source_version_count = description_versions(source).count
+    old_title = source.tag.reload.name('ja')
     old_body = source.body
 
     put "/wiki/#{ source.id }",
@@ -29,7 +30,7 @@ RSpec.describe 'Wiki title collision', type: :request do
           title: 'wiki_collision_target',
           body: 'new body',
           message: 'rename collision',
-          base_revision_id: source.current_revision.id,
+          base_revision_id: current_description_version(source).id,
         },
         headers: auth_headers(user)
 
@@ -37,26 +38,23 @@ RSpec.describe 'Wiki title collision', type: :request do
 
     source.reload
 
-    expect(source.title).to eq(old_title)
+    expect(source.tag.reload.name('ja')).to eq(old_title)
     expect(source.body).to eq(old_body)
-    expect(source.wiki_revisions.count).to eq(source_revision_count)
-    expect(source.wiki_versions.count).to eq(source_version_count)
+    expect(description_versions(source).count).to eq(source_revision_count)
+    expect(description_versions(source).count).to eq(source_version_count)
   end
 
-  it 'returns 422 when creating wiki with existing title' do
+  it 'rejects frozen creation with an existing title without adding history' do
     create_wiki_page(title: 'Help:wiki_collision_create', body: 'already exists')
 
-    expect {
+    expect do
       post '/wiki',
-           params: {
-             title: 'Help:wiki_collision_create',
-             body: 'new body',
-             message: 'duplicate create',
-           },
+           params: { title: 'Help:wiki_collision_create', body: 'new body',
+                     message: 'duplicate create' },
            headers: auth_headers(user)
-    }
-        .not_to change(WikiPage, :count)
+    end.to change(TagDescription, :count).by(0)
+        .and change(TagDescriptionVersion, :count).by(0)
 
-    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response.status).to be_between(400, 499)
   end
 end

backend/spec/requests/wiki_unmigrated_contract_spec.rb

@@ -1,115 +1,25 @@
 require 'rails_helper'
 
-RSpec.describe 'Unmigrated Wiki compatibility', type: :request do
-  let!(:user) { create_member_user! }
-  let!(:tag_name) { create(:tag_name, name: 'Help_contract') }
-  let!(:page) do
-    Wiki::Commit.create_content!(tag_name:, body: 'before', created_by_user: user)
-  end
-  let!(:first_revision) { page.current_revision }
-  let!(:last_revision) do
-    Wiki::Commit.content!(page:, body: 'after', created_user: user,
-                          message: 'legacy edit', base_revision_id: first_revision.id)
-  end
+RSpec.describe 'Removed standalone Wiki resources', type: :request do
+  include TagGroupRecords
+  let(:user) { create_member_user! }
 
-  before { expect(TagDescription.exists?(id: page.id)).to be(false) }
-
-  it 'keeps a Tag-linked legacy page in the legacy domain when its title changes' do
-    create(:tag, primary_tag_name: tag_name)
-
-    expect do
-      put "/wiki/#{ page.id }",
-          params: { title: 'legacy_tag_renamed', body: 'changed legacy body',
-                    message: 'legacy rename', base_revision_id: last_revision.id },
-          headers: { 'X-Transfer-Code' => user.inheritance_code }
-    end.to change(WikiRevision, :count).by(1)
-        .and change(WikiVersion, :count).by(1)
-        .and change(TagDescription, :count).by(0)
-        .and change(TagDescriptionVersion, :count).by(0)
-
-    expect(response).to have_http_status(:ok)
-    expect(page.reload).to have_attributes(body: 'changed legacy body')
-    expect(page.title).to eq('legacy_tag_renamed')
-    expect(page.current_revision).to have_attributes(message: 'legacy rename')
-  end
-
-  it 'shows legacy current and historical content by ID' do
-    get "/wiki/#{ page.id }"
-    expect(response).to have_http_status(:ok)
-    expect(json).to include('body' => 'after', 'revision_id' => last_revision.id,
-                           'pred' => first_revision.id, 'succ' => nil)
-    get "/wiki/#{ page.id }", params: { version: first_revision.id }
-    expect(response).to have_http_status(:ok)
-    expect(json).to include('body' => 'before', 'revision_id' => first_revision.id,
-                           'pred' => nil, 'succ' => last_revision.id)
-  end
-
-  it 'shows legacy current and historical content by title' do
-    get "/wiki/title/#{ tag_name.name }"
-    expect(response).to have_http_status(:ok)
-    expect(json).to include('body' => 'after', 'revision_id' => last_revision.id)
-    get "/wiki/title/#{ tag_name.name }", params: { version: first_revision.id }
-    expect(response).to have_http_status(:ok)
-    expect(json).to include('body' => 'before', 'revision_id' => first_revision.id)
-  end
-
-  it 'recognises legacy IDs' do
-    get "/wiki/#{ page.id }/exists"
-    expect(response).to have_http_status(:no_content)
-  end
-
-  it 'recognises legacy titles' do
-    get "/wiki/title/#{ tag_name.name }/exists"
-    expect(response).to have_http_status(:no_content)
-  end
-
-  it 'diffs legacy revisions with explicit and current target' do
-    [last_revision.id, nil].each do |to|
-      get "/wiki/#{ page.id }/diff", params: { from: first_revision.id, to: }
-      expect(response).to have_http_status(:ok)
-      expect(json).to include(
-          'wiki_page_id' => page.id, 'title' => tag_name.name,
-          'older_revision_id' => first_revision.id, 'newer_revision_id' => last_revision.id,
-          'diff' => [{ 'type' => 'removed', 'content' => 'before' },
-                     { 'type' => 'added', 'content' => 'after' }])
-    end
-  end
-
-  describe 'revision resource scope' do
-    let!(:other_page) do
-      Wiki::Commit.create_content!(
-          tag_name: create(:tag_name, name: 'Help_other_contract'),
-          body: 'other page history', created_by_user: user)
-    end
-    let(:other_revision) { other_page.current_revision }
-
-    it 'returns 404 when show specifies another page revision' do
-      get "/wiki/#{ page.id }", params: { version: other_revision.id }
+  ['Help:old', 'ヘルプ:旧ページ'].each do |title|
+    it "does not resolve #{ title } as a Wiki resource" do
+      path = "/wiki/title/#{ CGI.escapeURIComponent(title) }"
+      without_group_legacy_reads { get path }
+      expect(response).to have_http_status(:not_found)
+      get "#{ path }/exists"
       expect(response).to have_http_status(:not_found)
     end
 
-    it 'returns 404 when diff from belongs to another page' do
-      get "/wiki/#{ page.id }/diff",
-          params: { from: other_revision.id, to: last_revision.id }
-      expect(response).to have_http_status(:not_found)
+    it "rejects standalone creation of #{ title } without writes" do
+      user
+      before_state = group_state
+      post '/wiki', params: { title:, body: 'body' },
+           headers: { 'X-Transfer-Code' => user.inheritance_code }
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(group_state).to eq(before_state)
     end
-
-    it 'returns 404 when diff to belongs to another page' do
-      get "/wiki/#{ page.id }/diff",
-          params: { from: first_revision.id, to: other_revision.id }
-      expect(response).to have_http_status(:not_found)
-    end
-  end
-
-  it 'retains legacy history metadata and ordering' do
-    get '/wiki/changes', params: { id: page.id }
-    expect(response).to have_http_status(:ok)
-    expect(json.map { |row| row.fetch('revision_id') }).to eq(
-        [last_revision.id, first_revision.id])
-    expect(json.first).to include(
-        'pred' => first_revision.id, 'succ' => nil, 'kind' => 'content',
-        'message' => 'legacy edit', 'timestamp' => last_revision.created_at.iso8601(3),
-        'wiki_page' => { 'id' => page.id, 'title' => tag_name.name, 'deprecated_at' => nil },
-        'user' => { 'id' => user.id, 'name' => user.name })
   end
 end

backend/spec/services/post_bulk_creator_spec.rb

@@ -1,7 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe PostBulkCreator do
-  include_context 'English locale'
+  include_context 'Ainu locale'
 
   it 'limits workers to two and keeps failures in their request slots' do
     locale = Locale.nipponese
@@ -67,8 +67,7 @@ RSpec.describe PostBulkCreator do
     expect(results[3].dig(:post, :id)).to eq(4)
   end
 
-  it 'passes a future English locale to preflight and creation in every worker' do
-    pending '日本語以外の Locale 有効化は別課題で実装する'
+  it 'passes a future Ainu locale to preflight and creation in every worker' do
     locale
     actor = instance_double(User, id: 123)
     allow(User).to receive(:find).with(123).and_return(actor)

backend/spec/services/post_create_plan_spec.rb

@@ -11,23 +11,22 @@ RSpec.describe PostCreatePlan do
   end
 
   context 'with an explicit locale' do
-    include_context 'English locale'
+    include_context 'Ainu locale'
 
     it 'resolves the matching language identity and its parents' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
       locale
-      english_name = create(:tag_name, name: 'shared_name',
-                                      language_code: 'en', script_code: 'Latn')
-      english = create(:tag, primary_tag_name: english_name, category: :character)
+      ainu_name = create(:tag_name, name: 'shared_name',
+                                      language_code: 'ain', script_code: 'Kana')
+      ainu = create(:tag, primary_tag_name: ainu_name, category: :character)
       nipponese = create(:tag, primary_name: 'temporary_nipponese', category: :general)
       # The DB permits this identity; validation has its own contract spec.
       primary_tag_name_for(nipponese, 'ja').update_columns(name: 'shared_name')
-      english_parent_name = create(:tag_name, name: 'english_parent',
-                                            language_code: 'en', script_code: 'Latn')
-      english_parent = create(:tag, primary_tag_name: english_parent_name,
+      ainu_parent_name = create(:tag_name, name: 'ainu_parent',
+                                            language_code: 'ain', script_code: 'Kana')
+      ainu_parent = create(:tag, primary_tag_name: ainu_parent_name,
                                     category: :material)
       nipponese_parent = create(:tag, primary_name: 'nipponese_parent', category: :general)
-      TagImplication.create!(tag: english, parent_tag: english_parent)
+      TagImplication.create!(tag: ainu, parent_tag: ainu_parent)
       TagImplication.create!(tag: nipponese, parent_tag: nipponese_parent)
 
       plan = described_class.new(attributes: { tags: 'shared_name' }).build!(locale)
@@ -35,35 +34,34 @@ RSpec.describe PostCreatePlan do
       expect(plan[:direct_tag_specs]).to eq(
           [{ name: 'shared_name', category: :character }])
       expect(plan[:post_tag_specs]).to include(
-          { name: primary_tag_name_for(english_parent, 'en').name, category: :material })
+          { name: primary_tag_name_for(ainu_parent, 'ain').name, category: :material })
       expect(plan[:post_tag_specs].pluck(:name))
           .not_to include(primary_tag_name_for(nipponese_parent, 'ja').name)
     end
 
     it 'resolves aliases within the requested language' do
-      pending '日本語以外の Locale 有効化は別課題で実装する'
       locale
       nipponese = create(:tag, primary_name: 'nipponese_canonical')
-      english_name = create(:tag_name, name: 'english_canonical',
-                                      language_code: 'en', script_code: 'Latn')
-      english = create(:tag, primary_tag_name: english_name, category: :character)
+      ainu_name = create(:tag_name, name: 'ainu_canonical',
+                                      language_code: 'ain', script_code: 'Kana')
+      ainu = create(:tag, primary_tag_name: ainu_name, category: :character)
       nipponese_alias = create(:tag_name, :alias, name: 'shared_alias',
                                                   tag: nipponese)
-      english_alias = create(:tag_name, :alias, name: 'shared_alias',
-                                               tag: english,
-                                               language_code: 'en', script_code: 'Latn')
+      ainu_alias = create(:tag_name, :alias, name: 'shared_alias',
+                                               tag: ainu,
+                                               language_code: 'ain', script_code: 'Kana')
 
       expect(nipponese_alias.reload).to have_attributes(
           tag_id: nipponese.id,
           primary_flg: false, language_code: 'ja')
-      expect(english_alias.reload).to have_attributes(
-          tag_id: english.id,
-          primary_flg: false, language_code: 'en')
+      expect(ainu_alias.reload).to have_attributes(
+          tag_id: ainu.id,
+          primary_flg: false, language_code: 'ain')
 
       plan = described_class.new(attributes: { tags: 'shared_alias' }).build!(locale)
 
       expect(plan[:direct_tag_specs]).to eq(
-          [{ name: english_name.name, category: :character }])
+          [{ name: ainu_name.name, category: :character }])
     end
   end
 

backend/spec/services/post_creator_spec.rb

@@ -77,11 +77,10 @@ RSpec.describe PostCreator do
   end
 
   context 'with an explicit locale' do
-    include_context 'English locale'
+    include_context 'Ainu locale'
 
     [false, true].each do |planned|
       it "passes locale to tag creation with planned attributes: #{ planned }" do
-        pending '日本語以外の Locale 有効化は別課題で実装する'
         locale
         attributes = {
             title: 'Locale propagation',
@@ -97,8 +96,8 @@ RSpec.describe PostCreator do
 
         expect(Tag).to have_received(:find_or_create_by_tag_name!)
             .with(locale, 'locale_character', category: :character).at_least(:once)
-        tag_name = TagName.find_by!(language_code: 'en', name: 'locale_character')
-        expect(tag_name).to have_attributes(script_code: 'Latn', primary_flg: true)
+        tag_name = TagName.find_by!(language_code: 'ain', name: 'locale_character')
+        expect(tag_name).to have_attributes(script_code: 'Kana', primary_flg: true)
         expect(post.tags).to include(tag_name.tag)
       end
     end

backend/spec/services/shared_resource_id_allocator_mysql_spec.rb

@@ -0,0 +1,156 @@
+require 'rails_helper'
+require 'timeout'
+
+RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
+  self.use_transactional_tests = false
+
+  before do
+    expect(Rails.env.test?).to be(true)
+    expect(ApplicationRecord.connection.adapter_name).to match(/mysql/i)
+    expect(ApplicationRecord.connection_pool.size).to be >= 3
+    @prefix = "shared_ids_#{ SecureRandom.hex(8) }"
+    @tag = create(:tag, primary_name: "#{ @prefix }_owner")
+    @group = TagGroup.create!(name: "#{ @prefix }_owner", version_no: 1)
+    @tag_ids = Queue.new
+    @threads = []
+    @release = Queue.new
+  end
+
+  after do
+    @release << true if @release
+    begin
+      Array(@threads).each do |thread|
+        raise 'Shared ID worker did not finish' unless thread.join(15)
+      end
+    ensure
+      TagDescriptionVersion.where(tag_id: @tag.id).delete_all if @tag
+      if @group
+        TagGroupVersion.where(tag_group_id: @group.id).delete_all
+        @group.delete
+      end
+      if @prefix
+        ExternalTag.where(name: "#{ @prefix }_external").delete_all
+        TagGroup.where(name: "#{ @prefix }_group").delete_all
+      end
+      TagDescription.where(tag_id: @tag.id).delete_all if @tag
+      ids = []
+      ids << @tag_ids.pop until @tag_ids.empty? if @tag_ids
+      ids << @tag.id if @tag
+      TagName.where(tag_id: ids).delete_all
+      Tag.where(id: ids).delete_all
+    end
+  end
+
+  def await_queue queue
+    Timeout.timeout(15) { queue.pop }
+  end
+
+  def worker &block
+    Thread.new do
+      Thread.current.report_on_exception = false
+      ApplicationRecord.connection_pool.with_connection(&block)
+    end.tap { @threads << _1 }
+  end
+
+  def create_resource kind
+    case kind
+    when :tag
+      Tag.create!(category: :general).tap { @tag_ids << _1.id }
+    when :external
+      ExternalTag.create!(platform: :nico, name: "#{ @prefix }_external")
+    when :description
+      TagDescription.create!(tag: @tag, language_code: 'ja', body: '', version_no: 1)
+    when :description_version
+      TagDescriptionVersion.create!(
+          tag_id: @tag.id, language_code: 'ja', body: 'body', version_no: 1,
+          event_type: 'create', created_at: Time.current)
+    when :group_version
+      TagGroupVersion.create!(
+          tag_group: @group, name: @group.name, version_no: 1, event_type: 'create',
+          members: [], placements: [], created_at: Time.current)
+    when :group
+      TagGroup.create!(name: "#{ @prefix }_group", version_no: 1)
+    end
+  end
+
+  def hold_creation kind, rollback: false
+    ready = Queue.new
+    thread = worker do |connection|
+      id = nil
+      connection.transaction do
+        lock_name = nil
+        subscriber = lambda do |*args|
+          match = args.last.fetch(:sql).match(/GET_LOCK\('([^']+)'/)
+          lock_name = match[1] if match
+        end
+        ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') do
+          id = create_resource(kind).id
+        end
+        ready << [id, connection.select_value('SELECT CONNECTION_ID()').to_i, lock_name]
+        await_queue(@release)
+        raise ActiveRecord::Rollback if rollback
+      end
+      id
+    end
+    [thread, await_queue(ready)]
+  end
+
+  def result thread
+    raise 'Shared ID worker did not finish' unless thread.join(15)
+    thread.value
+  end
+
+  { tags: [:external, :tag], wiki: [:description, :group],
+    wiki_history: [:description_version, :group_version] }.each do |space, kinds|
+    [false, true].each do |rollback|
+      it "serialises #{ space } inserts through #{ rollback ? 'rollback' : 'commit' }" do
+        tables = SharedResourceIdAllocator::SPACES.fetch(space.to_s)
+        maxima = tables.map do |table|
+          ApplicationRecord.connection.select_value("SELECT MAX(id) FROM #{ table }").to_i
+        end
+        first, (first_id, connection_id, lock_name) = hold_creation(kinds.first, rollback:)
+        expect(first_id).to be > maxima.max
+        connection = ApplicationRecord.connection
+        quoted_lock = connection.quote(lock_name)
+        expect(connection.select_value("SELECT IS_USED_LOCK(#{ quoted_lock })").to_i)
+            .to eq(connection_id)
+
+        started = Queue.new
+        second = worker do |other|
+          started << other.select_value('SELECT CONNECTION_ID()').to_i
+          create_resource(kinds.last).id
+        end
+        expect(await_queue(started)).not_to eq(connection_id)
+        @release << true
+        expect(result(first)).to eq(first_id)
+        expect(result(second)).to be > first_id
+        expect(connection.select_value("SELECT IS_FREE_LOCK(#{ quoted_lock })").to_i).to eq(1)
+      end
+    end
+  end
+
+  it 'allows the other ID space to commit while the first space remains locked' do
+    first, (_id, connection_id, lock_name) = hold_creation(:external)
+    second = worker { create_resource(:group).id }
+    expect(result(second)).to be_positive
+    connection = ApplicationRecord.connection
+    quoted_lock = connection.quote(lock_name)
+    expect(connection.select_value("SELECT IS_USED_LOCK(#{ quoted_lock })").to_i)
+        .to eq(connection_id)
+    @release << true
+    result(first)
+  end
+
+  it 'raises on a real lock acquisition failure without inserting a record' do
+    first, (_id, _connection_id, lock_name) = hold_creation(:external, rollback: true)
+    stub_const('SharedResourceIdAllocator::LOCK_TIMEOUT', 0)
+    expect { create_resource(:external) }.to raise_error(ActiveRecord::LockWaitTimeout)
+    expect(ExternalTag.where(name: "#{ @prefix }_external")).not_to exist
+    @release << true
+    result(first)
+    connection = ApplicationRecord.connection
+    quoted_lock = connection.quote(lock_name)
+    expect(connection.select_value("SELECT IS_FREE_LOCK(#{ quoted_lock })").to_i)
+        .to eq(1)
+  end
+end