#424

backend/app/controllers/tag_descriptions_controller.rb

@@ -1,18 +1,14 @@
 class TagDescriptionsController < ApplicationController
   def show
-    locale = resolve_locale!
+    description = TagDescription.find_by(tag_id: params[:id], language_code: 'ja')
-    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
-    locale = resolve_locale!
+    tag_name = TagName.find_by(language_code: 'ja', name: params[:name].to_s.strip)
-    tag_name = TagName.find_by(
+    description = tag_name&.tag && TagDescription.find_by(tag: tag_name.tag, language_code: 'ja')
-        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)
@@ -25,19 +21,18 @@ 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: locale.language_code)
+    description = TagDescription.find_by(tag:, language_code: 'ja')
 
     if description
-      TagDescriptionOperation.update!(locale, tag:, body:, updated_by_user: current_user)
+      TagDescriptionOperation.update!(tag:, body:, updated_by_user: current_user)
       description.reload
       render json: representation(description)
     else
-      TagDescriptionOperation.create!(locale, tag:, body:, created_by_user: current_user)
+      TagDescriptionOperation.create!(tag:, body:, created_by_user: current_user)
-      description = TagDescription.find_by!(tag:, language_code: locale.language_code)
+      description = TagDescription.find_by!(tag:, language_code: 'ja')
       render json: representation(description), status: :created
     end
   rescue ActiveRecord::RecordInvalid => e

backend/app/controllers/tag_groups_controller.rb

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

backend/app/controllers/tags_controller.rb

@@ -770,15 +770,31 @@ class TagsController < ApplicationController
       TagVersioning.ensure_snapshot!(old_owner_tag, created_by_user: current_user)
     end
 
-    current_tag_name&.update!(primary_flg: false, auto_generated: false)
+    current_tag_name.wiki_page&.update!(tag_name_id: promoted_tag_name.id)
-    promoted_tag_name.update!(tag:, primary_flg: true, auto_generated: false)
+    current_tag_name.association(:wiki_page).reset
-    tag.association(:tag_names).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)
 
     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: promoted_tag_name.language_code)
+                        language_code: current_tag_name.language_code)
   end
 
   def update_aliases! locale, tag, alias_names
@@ -786,15 +802,20 @@ 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
 
-    requested_aliases = TagName.where(
+    current_aliases.each do |alias_tag_name|
-        language_code: locale.language_code, name: alias_names)
+      next if alias_names.include?(alias_tag_name.name)
-        .includes(:tag).index_by(&:name)
+
+      affected_tags << alias_tag_name.tag
+    end
 
     alias_names.each do |alias_name|
-      alias_tag_name = requested_aliases[alias_name]
+      alias_tag_name = TagName.find_by(language_code: locale.language_code, name: 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
@@ -802,8 +823,7 @@ class TagsController < ApplicationController
       affected_tags << alias_tag_name&.tag
     end
 
-    affected_tags = affected_tags.compact.uniq(&:id)
+    affected_tags.compact.uniq.each do |affected_tag|
-    affected_tags.each do |affected_tag|
       TagVersioning.ensure_snapshot!(affected_tag, created_by_user: current_user,
                                      language_code: locale.language_code)
     end
@@ -811,21 +831,19 @@ class TagsController < ApplicationController
     current_aliases.each do |alias_tag_name|
       next if alias_names.include?(alias_tag_name.name)
 
-      alias_tag_name.destroy!
+      alias_tag_name.update!(canonical_id: nil, tag_id: nil)
     end
 
     alias_names.each do |alias_name|
-      alias_tag_name = requested_aliases[alias_name] || TagName.new(
+      alias_tag_name = TagName.find_or_initialize_by(
           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)
+      alias_tag_name.update!(tag:, primary_flg: false, auto_generated: false,
+                             canonical_id: primary_tag_name.id)
     end
 
-    affected_tags.each do |affected_tag|
+    affected_tags.compact.uniq.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

@@ -1,15 +1,12 @@
 class WikiPagesController < ApplicationController
-  # 互換性のための Facade API
+  rescue_from Wiki::Commit::Conflict, with: :render_wiki_conflict
-
-  rescue_from TagDescriptionOperation::Conflict, with: :render_wiki_conflict
 
   def index
-    locale = resolve_locale!
+    # 互換性のための化石リソース
 
     title = params[:title].to_s.strip
     descriptions =
-        TagDescription
+        TagDescription.where(language_code: 'ja')
-        .where(language_code: locale.language_code)
         .includes(tag: :tag_names)
 
     descriptions = descriptions.order(updated_at: :desc, id: :asc)
@@ -18,14 +15,13 @@ class WikiPagesController < ApplicationController
       pattern = "%#{ ApplicationRecord.sanitize_sql_like(title) }%"
       descriptions =
           descriptions.joins(tag: :tag_names)
-          .where(tag_names: { language_code: locale.language_code, primary_flg: true })
+          .where(tag_names: { language_code: 'ja', primary_flg: true })
           .where('tag_names.name LIKE ?', pattern).limit(20)
       tag_groups = tag_groups.where(
-          'CONCAT(?, name) LIKE ? OR CONCAT(?, name) LIKE ?',
+          'CONCAT(?, name) LIKE ?', TagGroupRepr::PREFIX, pattern).limit(20)
-          TagGroupRepr::PREFIX, pattern, 'tag_group:', pattern).limit(20)
     end
 
-    json = descriptions.map { |description| WikiPageRepr.tag_description(locale, description) }
+    json = descriptions.map { |description| WikiPageRepr.tag_description(description) }
     json.concat(tag_groups.map { WikiPageRepr.tag_group(_1) })
     json.sort_by! do |row|
       [-row['updated_at'].to_f, row.fetch('resource_type'), row.fetch('id')]
@@ -35,53 +31,47 @@ class WikiPagesController < ApplicationController
   end
 
   def show
-    locale = resolve_locale!
+    tag_description = TagDescription.find_by(id: params[:id])
-    tag_description = TagDescription.find_by(id: params[:id], language_code: locale.language_code)
 
-    return render_wiki_page_by_tag_description locale, tag_description if tag_description
+    return render_wiki_page_by_tag_description tag_description if tag_description
 
     tag_group = TagGroup.find_by(id: params[:id])
-    return render_tag_group locale, tag_group if tag_group
+    return render_tag_group tag_group if tag_group
 
-    head :not_found
+    render_wiki_page_or_404 nil
   end
 
   def show_by_title
-    locale = resolve_locale!
     title = params[:title].to_s.strip
 
-    if (name = TagGroupRepr.name_from_title(title))
+    if title.start_with?(TagGroupRepr::PREFIX)
+      name = title.delete_prefix(TagGroupRepr::PREFIX)
       tag_group = TagGroup.find_by(name:)
-      return render_tag_group locale, tag_group if tag_group
+      return render_tag_group tag_group if tag_group
       return head :not_found
     end
 
-    tag_description = tag_description_by_title(locale, title)
+    tag_description = tag_description_by_title(title)
 
-    return render_wiki_page_by_tag_description locale, tag_description if tag_description
+    return render_wiki_page_by_tag_description tag_description if tag_description
 
-    head :not_found
+    render_wiki_page_or_404 nil
   end
 
   def exists
-    locale = resolve_locale!
+    return head :no_content if TagDescription.exists?(id: params[:id])
-    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 :not_found
   end
 
   def exists_by_title
-    locale = resolve_locale!
     title = params[:title].to_s.strip
-    if (name = TagGroupRepr.name_from_title(title))
+    if title.start_with?(TagGroupRepr::PREFIX)
-      exists = TagGroup.exists?(name:)
+      exists = TagGroup.exists?(name: title.delete_prefix(TagGroupRepr::PREFIX))
       return head exists ? :no_content : :not_found
     end
-
+    return head :no_content if tag_description_by_title(title)
-    return head :no_content if tag_description_by_title(locale, title)
 
     head :not_found
   end
@@ -90,17 +80,15 @@ class WikiPagesController < ApplicationController
     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:, language_code: locale.language_code)
+    description = TagDescription.find_by(id:)
     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(locale, description)
+      resource = WikiPageRepr.tag_description(description)
     else
       tag_group = TagGroup.find_by(id:)
       if tag_group
@@ -108,8 +96,8 @@ 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(locale, from_rev)
+        from_body = from_rev && render_group_version(from_rev)
-        to_body = render_group_version(locale, to_rev)
+        to_body = render_group_version(to_rev)
         resource = { 'id' => tag_group.id,
                      'title' => "#{ TagGroupRepr::PREFIX }#{ tag_group.name }",
                      'deprecated_at' => nil }
@@ -143,31 +131,30 @@ 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!
+    if title.start_with?(TagGroupRepr::PREFIX)
-
+      name = title.delete_prefix(TagGroupRepr::PREFIX)
-    if (name = TagGroupRepr.name_from_title(title))
+      parsed = TagGroupMarkdownParser.parse(body:, group: nil)
-      parsed = TagGroupMarkdownParser.parse(locale, body:, group: nil)
+      group = TagGroupOperation.create!(name:, **parsed, actor: current_user,
-      group = TagGroupOperation.create!(
+                                         require_compatibility: true)
-          locale, name:, **parsed.except(:compatibility_body), actor: current_user,
-          require_compatibility: true)
       version = current_group_version(group)
-      return render_group_representation(TagGroupRepr.one(locale, group), version,
+      return render_group_representation(TagGroupRepr.one(group), version,
+                                         body: parsed.fetch(:compatibility_body),
                                          status: :created)
     end
 
-    description =
+    page =
         if title.include?(':')
           return render_unprocessable_entity field: :title
         else
-          tag_name = TagName.find_by(language_code: locale.language_code, name: title)
+          tag_name = TagName.find_by(language_code: 'ja', 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
 
-    render json: WikiPageRepr.tag_description(locale, description), status: :created
+    description = TagDescription.find_by!(tag_id: page.tag_name.tag_id, language_code: 'ja')
+    render json: WikiPageRepr.tag_description(description), status: :created
   rescue ActiveRecord::RecordInvalid => e
     render_validation_error e.record
   rescue ActiveRecord::RecordNotUnique
@@ -186,30 +173,28 @@ 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 (name = TagGroupRepr.name_from_title(title))
+    if title.start_with?(TagGroupRepr::PREFIX)
       return head :not_found unless group
 
-      parsed = TagGroupMarkdownParser.parse(locale, body:, group:)
+      name = title.delete_prefix(TagGroupRepr::PREFIX)
-      TagGroupOperation.update!(
+      parsed = TagGroupMarkdownParser.parse(body:, group:)
-          locale, group:, name:, **parsed.except(:compatibility_body), actor: current_user,
+      TagGroupOperation.update!(group:, name:, **parsed, actor: current_user,
-          require_compatibility: true)
+                                require_compatibility: true)
       return head :ok
     end
 
     return render_unprocessable_entity field: :title if title.include?(':')
-    description = TagDescription.find_by(id: params[:id], language_code: locale.language_code)
+    description = TagDescription.find_by(id: params[:id])
     unless description
-      return render_unprocessable_entity field: :title if group
+      return render_unprocessable_entity field: :title if group || WikiPage.exists?(id: params[:id])
       return head :not_found
     end
-
     tag = description.tag
-    tag_name = tag.tag_name(locale.language_code)
+    tag_name = TagDescriptionOperation.compatibility_tag_name(tag)
-    return render_unprocessable_entity field: :title unless tag_name
+    if tag_name.name.include?(':') || (group && title != tag_name.name)
-    return render_unprocessable_entity field: :title if tag_name.name.include?(':')
+      return render_unprocessable_entity field: :title
+    end
 
     base_revision_id = params[:base_revision_id].presence
 
@@ -223,7 +208,7 @@ class WikiPagesController < ApplicationController
       tag_name.update!(name: title) if title != old_title
 
       message = params[:message].presence
-      TagDescriptionOperation.update!(locale, tag:, body:, updated_by_user: current_user,
+      TagDescriptionOperation.update!(tag:, body:, updated_by_user: current_user,
                                       message:, base_revision_id:)
 
       if title != old_title
@@ -242,12 +227,10 @@ class WikiPagesController < ApplicationController
   end
 
   def changes
-    locale = resolve_locale!
-
     id = params[:id].presence
-    description = id && TagDescription.find_by(id:, language_code: locale.language_code)
+    description = id && TagDescription.find_by(id:)
     if description
-      return render json: description_changes(locale, TagDescription.where(id: description.id))
+      return render json: description_changes(TagDescription.where(id: description.id))
     end
 
     tag_group = id && TagGroup.find_by(id:)
@@ -258,8 +241,7 @@ class WikiPagesController < ApplicationController
     json = []
     unless id
       json.concat(tag_group_changes(TagGroupVersion.all))
-      json.concat(description_changes(locale,
+      json.concat(description_changes(TagDescription.where(language_code: 'ja')))
-                                      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)
@@ -269,7 +251,27 @@ class WikiPagesController < ApplicationController
 
   private
 
-  def render_tag_group locale, group
+  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
     version = if params[:version].present?
       group_version(group, params[:version])
     else
@@ -277,17 +279,16 @@ class WikiPagesController < ApplicationController
     end
     return head :not_found unless version
 
-    representation =
+    representation = if params[:version].present?
-        if params[:version].present?
+      TagGroupRepr.historical(version)
-          TagGroupRepr.historical(locale, version)
+    else
-        else
+      TagGroupRepr.one(group)
-          TagGroupRepr.one(locale, group)
+    end
-        end
     render_group_representation(representation, version)
   end
 
-  def render_group_version locale, version
+  def render_group_version version
-    representation = TagGroupRepr.historical(locale, version)
+    representation = TagGroupRepr.historical(version)
     TagGroupMarkdownRenderer.render(representation)
   end
 
@@ -356,7 +357,28 @@ class WikiPagesController < ApplicationController
     end
   end
 
-  def render_wiki_page_by_tag_description locale, description
+  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
     versions = description_versions(description)
     historical = params[:version].present?
     rev = historical ? versions.find_by(id: params[:version]) :
@@ -367,7 +389,7 @@ 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(locale, description).merge(
+    render json: WikiPageRepr.tag_description(description).merge(
         body:, revision_id: rev.id, pred:, succ:, updated_at:)
   end
 
@@ -376,14 +398,13 @@ class WikiPagesController < ApplicationController
                                 language_code: description.language_code)
   end
 
-  def tag_description_by_title locale, title
+  def tag_description_by_title title
     TagDescription.joins(tag: :tag_names)
-        .find_by(language_code: locale.language_code,
+        .find_by(language_code: 'ja', tag_names: { language_code: 'ja', name: title })
-                 tag_names: { language_code: locale.language_code, name: title })
   end
 
-  def description_changes locale, descriptions
+  def description_changes descriptions
-    versions = TagDescriptionVersion.where(language_code: locale.language_code,
+    versions = TagDescriptionVersion.where(language_code: 'ja',
                                            tag_id: descriptions.select(:tag_id))
         .order(id: :desc).limit(200).to_a
     return [] if versions.empty?
@@ -392,7 +413,7 @@ 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: locale.language_code, tag_id: by_tag.keys,
+        language_code: 'ja', 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] }
@@ -402,7 +423,7 @@ 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(locale.language_code),
+        wiki_page: { id: description.id, title: description.tag.name('ja'),
                      deprecated_at: description.tag.deprecated_at },
         user: user && { id: user.id, name: user.name },
         kind: 'content',
@@ -411,6 +432,14 @@ 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/locale.rb

@@ -13,13 +13,14 @@ class Locale < ApplicationRecord
   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).includes(:tag_names).find_each do
+      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)
+                        auto_generated: true,
+                        canonical_id: nil)
       end
     end
   end

backend/app/models/tag.rb

@@ -91,6 +91,7 @@ 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)
@@ -259,13 +260,16 @@ class Tag < ApplicationRecord
       name = name.to_s.strip
 
       ApplicationRecord.transaction do
-        tn = TagName.find_by(language_code:, name:)
+        tn = TagName.find_or_create_by!(language_code:, name:) do
-        next tn.tag if tn
+          _1.script_code = locale.script_code
+          _1.primary_flg = true
+        end
 
-        tag = Tag.create!(category:)
+        tag = tn.tag
-        tn = TagName.create!(tag:, language_code:, name:,
+        next tag if tag
-                             script_code: locale.script_code, primary_flg: true,
+
-                             auto_generated: false)
+        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.association(:tag_names).reset
 
@@ -299,18 +303,20 @@ class Tag < ApplicationRecord
             end
           end
 
-          if source_tag.tag_descriptions.exists?
+          source_tag_name = source_tag.tag_name('ja')
-            source_tag.errors.add(:base, :invalid)
+
-            raise ActiveRecord::RecordInvalid, source_tag
+          if source_tag_name.wiki_page.present?
+            raise ActiveRecord::RecordInvalid.new(source_tag_name)
           end
 
           TagVersioning.record!(source_tag, event_type: :discard, created_by_user:)
-          target_languages = target_tag.tag_names.where(primary_flg: true).pluck(:language_code)
+          source_tag.tag_names.update_all(tag_id: target_tag.id, primary_flg: false,
-          source_tag.tag_names.where(language_code: target_languages)
+                                          updated_at: Time.current)
-              .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
 
@@ -370,7 +376,8 @@ class Tag < ApplicationRecord
                           name: TagName.generate_name(locale, tag, base_tag_name),
                           script_code:,
                           primary_flg: true,
-                          auto_generated: true)
+                          auto_generated: true,
+                          canonical_id: nil)
         end
       end
     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

@@ -1,6 +1,5 @@
 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
@@ -12,16 +11,8 @@ class TagGroup < ApplicationRecord
   has_many :placements, -> { order(:position) },
            class_name: 'TagGroupPlacement', dependent: :delete_all
   has_many :versions, -> { order(:version_no) },
-           class_name: 'TagGroupVersion'
+           class_name: 'TagGroupVersion', dependent: :delete_all
 
   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

@@ -1,8 +1,6 @@
 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

@@ -1,12 +1,14 @@
 class TagName < ApplicationRecord
   belongs_to :language, foreign_key: :language_code, primary_key: :code
-  belongs_to :tag
+  belongs_to :tag, optional: true
+  has_one :wiki_page
 
   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
@@ -19,16 +21,14 @@ 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?
+      if !tag_name || tag_name.primary? || tag_name.tag_id.nil?
         name
       else
-        primary_names[tag_name.tag_id] || name
+        TagName.find_by(language_code: locale.language_code,
+                        tag_id: tag_name.tag_id,
+                        primary_flg: true)&.name || name
       end
     }.uniq
   end
@@ -53,6 +53,12 @@ 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
     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．'

backend/app/models/tag_name_sanitisation_rule.rb

@@ -16,36 +16,37 @@ class TagNameSanitisationRule < ApplicationRecord
 
     def apply!
       Language.find_each do |language|
-        TagName.where(language:).find_each do |candidate|
+        TagName.where(language:).find_each do |tn|
+          name = sanitise(tn.name)
+          next if name == tn.name
+
           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:)
-            source_tag = tn.tag
+            if existing_tn
-            target_tag = existing_tn ? existing_tn.tag : source_tag
+              unless existing_tn.primary_flg
-            [source_tag, target_tag].uniq(&:id).sort_by(&:id).each(&:lock!)
+                existing_tn = TagName.find_by!(language:,
-            TagVersioning.ensure_snapshot!(source_tag, created_by_user: nil)
+                                               tag_id: existing_tn.tag_id,
-
+                                               primary_flg: true)
-            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
-            else
+              next if existing_tn.id == tn.id
-              # TagName 側の自動サニタイズを回避
+
-              tn.update_columns(name:, updated_at: Time.current)
+              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
             end
 
-            TagVersioning.record!(target_tag, event_type: :update, created_by_user: nil)
+            # TagName 側の自動サニタイズを回避
+            tn.update_columns(name:, updated_at: Time.current)
           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_tag_descriptions, class_name: 'TagDescription',
+  has_many :created_wiki_pages,
-           foreign_key: :created_by_user_id, dependent: :nullify
+           class_name: 'WikiPage', foreign_key: :created_user_id, dependent: :nullify
-  has_many :updated_tag_descriptions, class_name: 'TagDescription',
+  has_many :updated_wiki_pages,
-           foreign_key: :updated_by_user_id, dependent: :nullify
+           class_name: 'WikiPage', foreign_key: :updated_user_id, dependent: :nullify
 
   def viewed?(post) = user_post_views.exists?(post_id: post.id)
 

backend/app/models/wiki_line.rb

@@ -0,0 +1,15 @@
+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

@@ -0,0 +1,58 @@
+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

@@ -0,0 +1,55 @@
+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

@@ -0,0 +1,8 @@
+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

@@ -0,0 +1,8 @@
+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

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

backend/app/representations/wiki_page_repr.rb

@@ -2,14 +2,19 @@
 
 
 module WikiPageRepr
+  BASE = { methods: [:title, :deprecated_at] }.freeze
+
   module_function
 
-  def tag_description locale, description
+  def base wiki_page
-    tag = description.tag
+    wiki_page.as_json(BASE)
+  end
 
+  def tag_description description
+    tag = description.tag
     { 'id' => description.id,
       'resource_type' => 'tag_description',
-      'tag_name_id' => tag.tag_name(locale.language_code)&.id,
+      'tag_name_id' => tag.tag_name('ja')&.id,
       'body' => description.body,
       'created_user_id' => description.created_by_user_id,
       'updated_user_id' => description.updated_by_user_id,
@@ -17,11 +22,15 @@ module WikiPageRepr
       'updated_at' => description.updated_at,
       'discarded_at' => nil,
       'version_no' => description.version_no,
-      'title' => tag.name(locale.language_code),
+      'title' => tag.name('ja'),
       'deprecated_at' => tag.deprecated_at }
   end
 
   def tag_group tag_group
     TagGroupRepr.tag_group(tag_group).merge('resource_type' => 'tag_group')
   end
+
+  def many wiki_pages
+    wiki_pages.map { |p| base(p) }
+  end
 end

backend/app/services/post_create_plan.rb

@@ -95,10 +95,14 @@ 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
@@ -113,9 +117,9 @@ class PostCreatePlan
   end
 
   def validate_new_tag_spec! locale, spec
-    tag = Tag.new(category: spec[:category])
+    tag_name = TagName.new(name: spec[:name], language_code: locale.language_code,
-    tag_name = TagName.new(tag:, name: spec[:name], language_code: locale.language_code,
                            script_code: locale.script_code, primary_flg: true)
+    tag = Tag.new(category: spec[:category])
     return if tag_name.valid? && tag.valid?
 
     post = Post.new
@@ -136,10 +140,10 @@ class PostCreatePlan
     end
     expanded_parent_specs =
         Tag.expand_parent_tags(existing_snapshot_tags)
-        .reject(&:deprecated?)
+           .reject(&:deprecated?)
-        .map { |tag|
+           .map { |tag|
-          { name: tag.name(locale.language_code),
+             { name: tag.name(locale.language_code),
-            category: tag.category.to_sym }
+               category: tag.category.to_sym }
         }
     merge_tag_specs(snapshot_tag_specs + expanded_parent_specs)
   end
@@ -160,10 +164,9 @@ 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
+      TagName.where(language_code: locale.language_code, primary_flg: true, name: names)
-          .where(language_code: locale.language_code, primary_flg: true, name: names)
+             .includes(:tag)
-          .includes(:tag)
+             .each_with_object({ }) { |tag_name, tags| tags[tag_name.name] = tag_name.tag }
-          .each_with_object({ }) { |tag_name, tags| tags[tag_name.name] = tag_name.tag }
     end
   end
 

backend/app/services/shared_resource_id_allocator.rb

@@ -4,14 +4,7 @@ require 'digest'
 class SharedResourceIdAllocator
   SPACES = {
       'tags' => ['tags', 'external_tags'],
-      'wiki' => ['tag_descriptions', 'tag_groups'],
+      'wiki' => ['tag_descriptions', 'tag_groups'] }.freeze
-      '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
@@ -20,9 +13,7 @@ class SharedResourceIdAllocator
 
     connection = record.class.connection
     transaction = record.class.current_transaction
-    unless transaction.open?
+    raise ActiveRecord::ActiveRecordError, 'Shared ID requires a 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 }"
@@ -50,42 +41,16 @@ class SharedResourceIdAllocator
       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
+    # Locking reads see committed maxima even after earlier repeatable reads.
-      historical_max = HISTORY_IDS.fetch(space, []).map { |table, column|
+    maxima = record.class.uncached do
+      tables.map do |table|
         quoted_table = connection.quote_table_name(table)
-        quoted_column = connection.quote_column_name(column)
+        connection.select_value(
-        connection.select_value("SELECT MAX(#{ quoted_column }) FROM #{ quoted_table }").to_i
+            "SELECT id FROM #{ quoted_table } ORDER BY id DESC LIMIT 1 FOR UPDATE").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
+    record.id = maxima.max + 1
   end
-  private_class_method :next_ids
 end

backend/app/services/tag_description_operation.rb

@@ -1,67 +1,72 @@
 class TagDescriptionOperation
-  class Conflict < StandardError
+  LANGUAGE_CODE = 'ja'
-    ;
-  end
 
-  def self.create! locale, tag:, body:, created_by_user:, message: nil
+  def self.create!(tag:, body:, created_by_user:, message: nil)
     ApplicationRecord.transaction do
       tag.lock!
       raise ActiveRecord::RecordNotUnique if TagDescription.exists?(
-          tag_id: tag.id, language_code: locale.language_code)
+          tag_id: tag.id, language_code: LANGUAGE_CODE)
 
-      description = TagDescription.new(tag:, language_code: locale.language_code)
+      page = Wiki::CompatibilityWriter.create!(
-      body = normalise_body!(description, body)
+          tag_name: compatibility_tag_name(tag), body:, created_by_user:, message:)
-      record_version!(description:, body:, user: created_by_user)
+      revision = page.wiki_revisions.order(id: :desc).first
-
+      record_version!(tag:, revision:, body: revision.body, user: created_by_user,
-      description
+                      description: nil)
+      page
     end
   end
 
-  def self.update! locale, tag:, body:, updated_by_user:, message: nil, base_revision_id: nil
+  def self.update!(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: locale.language_code)
+          tag_id: tag.id, language_code: LANGUAGE_CODE)
-      body = normalise_body!(description, body)
+      tag_name = compatibility_tag_name(tag)
-      latest = TagDescriptionVersion.find_by(
+      page = WikiPage.lock.find_by(tag_name_id: tag_name.id)
-          tag_id: tag.id, language_code: locale.language_code,
+      unless page
-          version_no: description.version_no)
+        versions = TagDescriptionVersion.where(tag_id: tag.id, language_code: LANGUAGE_CODE)
-      if base_revision_id.present? && latest&.id != base_revision_id.to_i
+        if base_revision_id.present? && versions.maximum(:id) != base_revision_id.to_i
-        raise Conflict, '競合が発生してゐます．'
+          raise Wiki::Commit::Conflict, '競合が発生してゐます．'
+        end
+        page = Wiki::CompatibilityWriter.create!(
+            tag_name:, body:, created_by_user: updated_by_user, message:)
+        revision = page.current_revision
+        record_version!(tag:, revision:, body: revision.body,
+                        user: updated_by_user, description:)
+        next revision
       end
-      next if latest && normalise_body(description.body) == body
+      revision = Wiki::CompatibilityWriter.update!(
+          page:, body:, updated_by_user:, message:,
+          base_revision_id:)
+      next unless revision
 
-      record_version!(description:, body:, user: updated_by_user)
+      record_version!(tag:, revision:, body: revision.body,
+                      user: updated_by_user, description:)
+      revision
     end
   end
 
-  def self.record_version! description:, body:, user:
+  def self.compatibility_tag_name tag
-    creating = description.new_record?
+    tag.tag_name(LANGUAGE_CODE) || TagName.find_by!(id: tag.tag_name_id,
-    version_no = creating ? 1 : description.version_no + 1
+                                                  language_code: LANGUAGE_CODE)
-    description.created_by_user_id = user.id if creating
+  end
-    description.update!(body:, version_no:, updated_by_user_id: user.id)
+
+  def self.record_version! tag:, revision:, body:, user:, description:
+    version_no = description ? description.version_no + 1 : 1
     TagDescriptionVersion.create!(
-        tag_id: description.tag_id, language_code: description.language_code,
+        id: revision.id, tag_id: tag.id, language_code: LANGUAGE_CODE,
-        version_no:, event_type: creating ? 'create' : 'update', body:,
+        version_no:, event_type: description ? 'update' : 'create', body:,
-        source_language_code: description.source_language_code,
+        created_by_user_id: user.id, created_at: revision.created_at)
-        source_version_no: description.source_version_no,
+    if description
-        created_by_user_id: user.id, created_at: Time.current)
+      description.update!(body:, version_no:, updated_by_user_id: user.id)
+    else
+      TagDescription.create!(
+          tag_id: tag.id,
+          language_code: LANGUAGE_CODE, version_no:, body:,
+          created_by_user_id: user.id, updated_by_user_id: user.id)
+    end
   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(locale, body:, group: nil)
+  def self.parse(body:, group: nil)
-    new(body:, group:).parse(locale)
+    new(body:, group:).parse
   end
 
   def initialize(body:, group:)
@@ -16,7 +16,7 @@ class TagGroupMarkdownParser
     @group = group
   end
 
-  def parse locale
+  def parse
     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(locale, _1) })
+        target.concat(node.children.map { parse_list_item(_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 locale, item
+  def parse_list_item(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?
 
@@ -81,30 +81,29 @@ 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 =
+    node = if label.start_with?(PREFIX)
-        if (group_name = TagGroupRepr.name_from_title(label))
+      group_name = label.delete_prefix(PREFIX).strip
-          group_name = group_name.strip
+      child_group = TagGroup.find_by(name: group_name)
-          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!("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
-          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 }
-          { 'tag_group_id' => child_group.id }
+    elsif label.end_with?(':', '：')
-        elsif label.end_with?(':', '：')
+      section_name = label.sub(/[:：]\z/, '').strip
-          section_name = label.sub(/[:：]\z/, '').strip
+      invalid!('Section 名は必須です．') if section_name.blank?
-          invalid!('Section 名は必須です．') if section_name.blank?
+      { 'section_name' => section_name, 'description' => nil }
-          { 'section_name' => section_name, 'description' => nil }
+    else
-        else
+      { 'tag_id' => resolve_tag(label) }
-          { 'tag_id' => resolve_tag(locale, label) }
+    end
-        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(locale, _1) }
+      list.children.map { parse_list_item(_1) }
     end
     node
   end
 
-  def resolve_tag locale, name
+  def resolve_tag(name)
-    names = TagName.where(language_code: locale.language_code, name:).to_a
+    names = TagName.where(language_code: 'ja', 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

@@ -19,20 +19,15 @@ class TagGroupMarkdownRenderer
       blocks << clean_text(@group['description'])
     end
 
-    first_section = placements.index { _1.key?('section_name') }
+    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
 
-    if first_section
+    if placements.all? { _1.key?('section_name') }
-      if placements.drop(first_section).any? { !_1.key?('section_name') }
+      blocks.concat(placements.map { render_heading(_1, 2) })
-        raise UnsupportedStructure,
+    else
-            '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
 
@@ -79,7 +74,7 @@ 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

@@ -1,51 +1,49 @@
 class TagGroupOperation
   MAX_PLACEMENT_DEPTH = 5
+  PREFIX = TagGroupRepr::PREFIX
 
-  def self.create!(locale, name:, description:, members:, placements:, actor:,
+  def self.create!(name:, description:, members:, placements:, actor:,
-                   require_compatibility: false)
+                   require_compatibility: false, compatibility_body: nil)
-    ApplicationRecord.transaction do
+    group, sync_issue = ApplicationRecord.transaction do
       group = TagGroup.new(version_no: 1, created_by_user: actor,
                            updated_by_user: actor)
-      attributes = prepare!(locale:, group:, name:, description:, members:, placements:)
+      attributes = prepare!(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')
-      group
+      issue = sync_compatibility!(group:, actor:, old_name: nil,
+                                  require_compatibility:, compatibility_body:)
+      [group, issue]
     end
+    report_sync_issue(group, actor, sync_issue)
+    group
   end
 
-  def self.update!(locale, group:, name:, description:, members:, placements:, actor:,
+  def self.update!(group:, name:, description:, members:, placements:, actor:,
-                   require_compatibility: false)
+                   require_compatibility: false, compatibility_body: nil)
-    ApplicationRecord.transaction do
+    group, sync_issue = ApplicationRecord.transaction do
       group.lock!
-      attributes = prepare!(locale:, group:, name:, description:, members:, placements:)
+      old_name = group.name
-      if unchanged?(group, attributes)
+      attributes = prepare!(group:, name:, description:, members:, placements:)
-        validate_compatibility!(locale, group) if require_compatibility
+      next [group, nil] if unchanged?(group, attributes)
-        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')
-      group
+      issue = sync_compatibility!(group:, actor:, old_name:,
+                                  require_compatibility:, compatibility_body:)
+      [group, issue]
     end
+    report_sync_issue(group, actor, sync_issue)
+    group
   end
 
-  def self.validate_compatibility! locale, group
+  def self.prepare!(group:, name:, description:, members:, placements:)
-    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?
@@ -63,7 +61,7 @@ class TagGroupOperation
 
     member_rows = normalize_members(record, members)
     placement_tree = normalize_placements(record, placements)
-    validate_references!(locale, record, member_rows, placement_tree)
+    validate_references!(record, member_rows, placement_tree)
     validate_containment!(record, member_rows)
     { name: normalized_name, description:, members: member_rows,
       placements: placement_tree }
@@ -187,7 +185,7 @@ class TagGroupOperation
   end
   private_class_method :normalize_placement_nodes
 
-  def self.validate_references!(locale, record, members, placements)
+  def self.validate_references!(record, members, placements)
     membership = members.to_set
     placed = placement_references(placements).uniq
     missing = placed - membership.to_a
@@ -206,14 +204,13 @@ 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_names = TagName.where(tag_id: tag_ids, language_code: 'ja', primary_flg: true)
-        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, :invalid) unless
+        invalid!(record, :members, "Tag ##{ id } に日本語の正規名がありません．") unless
             tag_names.include?(id)
         version_no = tags.fetch(id).version_no
         unless tag_versions.include?([id, version_no])
@@ -316,6 +313,57 @@ 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::CompatibilityWriter.create!(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/wiki/commit.rb

@@ -0,0 +1,164 @@
+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' && !tag_name.name.include?(':')
+        return TagDescriptionOperation.create!(
+            tag: tag_name.tag, body:, created_by_user:, message:)
+      end
+
+      tag_name.errors.add(:base, :invalid)
+      raise ActiveRecord::RecordInvalid, tag_name
+    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(tag_id: page.tag_name.tag_id, language_code: 'ja')
+      description ||= TagDescription.joins(:tag).find_by(
+          tags: { tag_name_id: page.tag_name_id }, language_code: 'ja')
+      if description && !page.title.include?(':')
+        return TagDescriptionOperation.update!(
+            tag: description.tag, body:, updated_by_user: created_user,
+            message:, base_revision_id:)
+      end
+
+      page.errors.add(:base, :invalid)
+      raise ActiveRecord::RecordInvalid, page
+    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

@@ -0,0 +1,43 @@
+module Wiki
+  class CompatibilityWriter
+    def self.create! tag_name:, body:, created_by_user:, message: nil
+      ApplicationRecord.transaction do
+        tag_name.lock!
+        page = WikiPage.lock.find_by(tag_name_id: tag_name.id)
+        if page
+          update!(page:, body:, updated_by_user: created_by_user, message:)
+          page
+        else
+          Commit.create_legacy_content!(tag_name:, body:, created_by_user:, message:)
+        end
+      end
+    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
+
+      if Commit.normalise_body(page.body) == normalised && page.wiki_revisions.exists?
+        return
+      end
+
+      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

@@ -0,0 +1,21 @@
+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/db/migrate/20261015000000_drop_wiki_pages.rb

@@ -1,9 +0,0 @@
-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

@@ -1,11 +0,0 @@
-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

@@ -1,15 +0,0 @@
-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_15_010000) do
+ActiveRecord::Schema[8.0].define(version: 2026_10_08_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
@@ -578,15 +578,17 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
   end
 
   create_table "tag_names", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.bigint "tag_id", null: false
+    t.bigint "tag_id"
     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"
@@ -623,6 +625,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_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
@@ -630,6 +633,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_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
@@ -769,6 +773,76 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_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"
@@ -841,10 +915,12 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_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"
@@ -869,4 +945,15 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_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/spec/db/tag_description_migration_spec.rb

@@ -0,0 +1,34 @@
+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_legacy_content!(
+        tag_name:, body: 'A', created_by_user: user)
+    revisions = [page.current_revision]
+    ['A', 'B', 'B', 'A'].each do |body|
+      revisions << Wiki::Commit.legacy_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

@@ -0,0 +1,119 @@
+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

@@ -1,17 +1,11 @@
 require 'rails_helper'
 
 RSpec.describe 'TagName database invariants' do
-  def insert_name! **attributes
+  def insert_name!(**attributes)
-    defaults = {
+    TagName.insert_all!([{ name: 'constraint_name', language_code: 'ja',
-        tag_id: create(:tag, primary_tag_name: nil).id,
+                          script_code: 'Jpan', primary_flg: true,
-        name: 'constraint_name',
+                          created_at: Time.current, updated_at: Time.current,
-        language_code: 'ja',
+                          **attributes }])
-        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
@@ -39,9 +33,4 @@ 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

@@ -1,23 +0,0 @@
-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

@@ -6,8 +6,6 @@ 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, tag: nil, **attributes)
+        build(:tag_name, **attributes)
       end
     end
 
@@ -12,16 +12,17 @@ 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
 
-    after(:create) do |tag, evaluator|
+    before(:create) do |tag, evaluator|
-      next unless evaluator.primary_tag_name
+      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|
       evaluator.primary_tag_name.update!(tag:, primary_flg: true)
 
       Locale.where(deprecated_at: nil).order(:language_code, :created_at, :script_code).to_a

backend/spec/factories/wiki_pages.rb

@@ -0,0 +1,9 @@
+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/shared_tag_ids_spec.rb

@@ -1,37 +1,84 @@
 require 'rails_helper'
 
 RSpec.describe 'Shared Tag and ExternalTag IDs', type: :model do
-  it 'allocates distinct increasing IDs across the two tables' do
+  include TagGroupRecords
-    tag = create(:tag)
+  let(:user) { create_member_user! }
-    external = create(:external_tag)
-    next_tag = create(:tag)
 
-    expect(external.id).to be > tag.id
+  def create_resource resource
-    expect(next_tag.id).to be > external.id
+    if resource == :tag
+      Tag.find_or_create_by_tag_name!(Locale.nipponese, 'shared_id_new', category: :general)
+    else
+      ExternalTag.create!(platform: :nico, name: 'shared_id_new')
+    end
   end
 
-  it 'does not reuse physically deleted IDs in either table' do
+  [:tag, :external_tag].each do |resource|
-    tag = create(:tag)
+    it "starts #{ resource } at 1 when both tables are empty" do
-    external = create(:external_tag)
+      expect(Tag.count).to eq(0)
-    TagName.where(tag_id: tag.id).delete_all
+      expect(ExternalTag.count).to eq(0)
-    tag.destroy!
+      expect(create_resource(resource).id).to eq(1)
-    external.destroy!
+    end
 
-    expect(create(:tag).id).to be > external.id
+    it "allocates #{ resource } above the other table's maximum" do
-    expect(create(:external_tag).id).to be > external.id
+      create(:tag, id: resource == :tag ? 1 : 20)
+      create(:external_tag, id: resource == :external_tag ? 1 : 20)
+
+      expect(create_resource(resource).id).to eq(21)
+    end
+
+    it "uses the current maximum after deleting earlier #{ resource } records" do
+      tag = create(:tag, id: 100)
+      TagName.where(tag_id: tag.id).update_all(tag_id: nil)
+      tag.destroy!
+      create(:external_tag, id: 200).destroy!
+      expect(Tag.unscoped.count).to eq(0)
+      expect(ExternalTag.unscoped.count).to eq(0)
+      expect(create_resource(resource).id).to eq(1)
+    end
+
+    it "preserves legacy overlaps and gaps when creating #{ resource }" do
+      [1, 2, 5].each { create(:tag, id: _1) }
+      [1, 3, 8].each { create(:external_tag, id: _1) }
+      tags = Tag.order(:id).map(&:attributes)
+      external_tags = ExternalTag.order(:id).map(&:attributes)
+
+      record = create_resource(resource)
+
+      aggregate_failures do
+        expect(record.id).to eq(9)
+        expect(Tag.where(id: [1, 2, 5]).order(:id).map(&:attributes)).to eq(tags)
+        expect(ExternalTag.where(id: [1, 3, 8]).order(:id).map(&:attributes)).to eq(external_tags)
+        expect(Tag.exists?(id: 3)).to be(false)
+        expect(ExternalTag.exists?(id: 2)).to be(false)
+      end
+    end
+
+    it "ignores the description and group ID space when creating #{ resource }" do
+      tag = create(:tag, id: 1)
+      create(:external_tag, id: 2)
+      TagDescription.create!(id: 100, tag:, language_code: 'ja', body: '', version_no: 1)
+      seed_group(name: 'separate_space', id: 200)
+
+      expect(create_resource(resource).id).to eq(3)
+    end
   end
 
-  it 'retains existing overlapping IDs without renumbering on update or insert' do
+  it 'preserves overlapping IDs during updates without rewriting the other resource' do
-    tag = create(:tag)
+    tag = create(:tag, id: 5)
-    external = create(:external_tag)
+    external = create(:external_tag, id: 5)
-    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.id).to eq(5)
-    expect(tag.reload.attributes).to eq(before_tag)
+    expect(external.reload.id).to eq(5)
-    expect(external.reload.attributes).to eq(before_external)
+    expect(tag.category).to eq('meta')
+    expect(external.name).to eq('updated_external')
+    expect(Tag.count).to eq(1)
+    expect(ExternalTag.count).to eq(1)
+  end
+
+  it 'allocates distinct IDs for successive creations across both tables' do
+    records = [:tag, :external_tag].map { create_resource(_1) }
+    expect(records.map(&:id)).to eq([1, 2])
   end
 end

backend/spec/models/tag_group_spec.rb

@@ -1,48 +0,0 @@
-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

@@ -34,66 +34,6 @@ 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'
 
@@ -158,6 +98,25 @@ 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

@@ -22,23 +22,16 @@ RSpec.describe TagName, type: :model do
     expect(duplicate.errors.of_kind?(:name, :taken)).to be(true)
   end
 
-  it 'creates Nipponese factory names with an owning tag' do
+  it 'creates Nipponese factory names without requiring a 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: name.tag.id)
+        auto_generated: false, tag_id: nil)
-  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!(tag: create(:tag, primary_tag_name: nil),
+    name = described_class.create!(name: 'ordinary_human_name', language_code: 'ja',
-                                   name: 'ordinary_human_name', language_code: 'ja',
                                    script_code: 'Jpan', primary_flg: true)
 
     expect(name.reload.auto_generated).to be(false)
@@ -53,7 +46,7 @@ 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('ja')&.id).to eq(name.id)
+    expect(tag.reload.tag_name_id).to eq(name.id)
   end
 
   it 'creates a complete ordinary tag factory under the active Nipponese language' do
@@ -103,14 +96,19 @@ 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 'resolves an alias to its owning primary name' do
+    it 'does not resolve a detached alias through another detached primary' do
-      tag = create(:tag, primary_name: 'canonical')
+      create(:tag_name, :alias, name: 'detached_alias')
-      create(:tag_name, :alias, tag:, name: 'alias')
+      create(:tag_name, name: 'unrelated_detached_primary')
 
-      expect(described_class.canonicalise(Locale.nipponese, ['alias', 'unknown']))
+      expect(described_class.canonicalise(Locale.nipponese, ['detached_alias']))
-          .to eq(['canonical', 'unknown'])
+          .to eq(['detached_alias'])
     end
 
     it 'resolves the primary name of the alias language on the same tag' do
@@ -121,7 +119,7 @@ RSpec.describe TagName, type: :model do
       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('ja')&.id
+      representative_id = tag.tag_name_id
 
       primary = described_class.find_by!(tag_id: english_alias.tag_id,
                                          language_code: english_alias.language_code,
@@ -130,7 +128,7 @@ RSpec.describe TagName, type: :model do
       expect(primary).to eq(english_primary)
       expect(described_class.canonicalise(locale, [english_alias.name]))
           .to eq([english_primary.name])
-      expect(tag.reload.tag_name('ja')&.id).to eq(representative_id)
+      expect(tag.reload.tag_name_id).to eq(representative_id)
     end
 
     it 'resolves only aliases in the requested language' do

backend/spec/models/tag_spec.rb

@@ -1,7 +1,6 @@
 require 'rails_helper'
 
 RSpec.describe Tag, type: :model do
-  include WikiRecords
   describe '#has_description?' do
     let(:tag) { create(:tag) }
 
@@ -15,6 +14,12 @@ RSpec.describe Tag, type: :model do
       expect(tag.has_description?(language_code: 'ja')).to be(false)
     end
 
+    it 'does not use a Wiki page as evidence of a description' do
+      user = create_member_user!
+      Wiki::Commit.create_legacy_content!(tag_name: tag.tag_name('ja'), body: 'legacy',
+                                          created_by_user: user)
+      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)
@@ -329,7 +334,38 @@ RSpec.describe Tag, type: :model do
             .where(tag_names: { name: 'atomic_english_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'
@@ -354,7 +390,7 @@ RSpec.describe Tag, type: :model 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('ja')&.id
+        representative_id = tag.tag_name_id
         english = primary_tag_name_for(tag, 'en')
         english.update!(name: 'english_primary', auto_generated: false)
 
@@ -362,7 +398,7 @@ RSpec.describe Tag, type: :model do
             locale, english.name, category: :general)
 
         expect(found).to eq(tag)
-        expect(tag.reload.tag_name('ja')&.id).to eq(representative_id)
+        expect(tag.reload.tag_name_id).to eq(representative_id)
         expect(english.reload.tag_id).to eq(tag.id)
       end
 
@@ -394,10 +430,22 @@ 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('ja')&.id
+      representative_id = tag.tag_name_id
       alias_name = create(:tag_name, :alias, name: 'lookup_alias', tag:)
       expect(alias_name.reload).to have_attributes(
           tag_id: tag.id,
@@ -411,7 +459,7 @@ RSpec.describe Tag, type: :model do
 
       expect(found).to eq(tag)
       expect(found.category).to eq('character')
-      expect(tag.reload.tag_name('ja')&.id).to eq(representative_id)
+      expect(tag.reload.tag_name_id).to eq(representative_id)
     end
 
     it 'reuses the owning tag through another alias' do
@@ -635,7 +683,7 @@ RSpec.describe Tag, type: :model do
       let!(:wiki_page) do
         admin = create_admin_user!
 
-        seed_description(
+        Wiki::Commit.create_content!(
             tag_name: source_tag_name,
             body: 'source wiki body',
             created_by_user: admin,

backend/spec/models/user_spec.rb

@@ -1,25 +0,0 @@
-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/materials_spec.rb

@@ -222,26 +222,28 @@ RSpec.describe 'Materials API', type: :request do
       expect(queries).to be_empty
     end
 
-    it 'reads the description even when the stored version has different content' do
+    it 'reads the description even when the legacy revision has different content' do
-      page = seed_description(tag_name: tag.tag_name('ja'), body: 'legacy body',
+      page = seed_wiki_page(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')
+      expect(page.current_revision.body).to eq('legacy body')
     end
 
-    it 'uses tag_id rather than description Id. without a Wiki page' do
+    it 'uses tag_id rather than description ID without a Wiki page or TagName' do
-      description = TagDescription.create!(tag:, language_code: 'ja',
+      description = TagDescription.create!(id: tag.id + 1000, tag:, language_code: 'ja',
                                            body: 'independent body', version_no: 1)
+      tag.tag_names.update_all(tag_id: nil)
       get_material_without_legacy_reads
+      expect(description.id).not_to eq(tag.id)
       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
+    it 'returns nil when only legacy Wiki content exists' do
-      seed_description(tag_name: tag.tag_name('ja'), body: 'legacy only',
+      seed_wiki_page(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

backend/spec/requests/tag_description_wiki_spec.rb

@@ -4,21 +4,34 @@ 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!(:tag) { tag_name.tag }
+  let!(:page) do
+    seed_wiki_page(
+        tag_name:, body: 'old-revision', created_by_user: user)
+  end
+  let!(:revisions) do
+    first = page.current_revision
+    second = Wiki::Commit.legacy_content!(page:, body: 'old-second', created_user: user)
+    third = Wiki::Commit.legacy_content!(page:, body: 'old-third', created_user: user)
+    [first, second, third]
+  end
+  let!(:tag) { create(:tag, primary_tag_name: tag_name) }
   let!(:versions) do
-    ['A', 'A', 'new-version'].each_with_index.map do |body, index|
+    revisions.each_with_index.map do |revision, index|
       TagDescriptionVersion.create!(
-          tag_id: tag.id, language_code: 'ja', version_no: index + 1,
+          id: revision.id, tag_id: tag.id, language_code: 'ja',
-          event_type: index.zero? ? 'create' : 'update', body:,
+          version_no: index + 1, event_type: index.zero? ? 'create' : 'update',
-          created_by_user_id: user.id, created_at: Time.current)
+          body: index == 2 ? 'new-version' : 'A',
+          created_by_user_id: user.id, created_at: revision.created_at)
     end
   end
   let!(:description) do
     TagDescription.create!(
-        tag:, language_code: 'ja', version_no: 3, body: 'new',
+        id: page.id, 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 = []
@@ -57,7 +70,7 @@ 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: versions.first.id }
+        get "/wiki/#{ description.id }", params: { version: revisions.first.id }
       end
       expect(response).to have_http_status(:not_found)
     end
@@ -119,6 +132,16 @@ 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
@@ -132,6 +155,28 @@ 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
@@ -184,8 +229,39 @@ 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 'excludes unmigrated history and migrated legacy-only revisions' do
+      legacy_page = seed_wiki_page(
+          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).not_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

@@ -1,94 +1,281 @@
 require 'rails_helper'
 
-RSpec.describe 'Tag description Wiki facade writes', type: :request do
+RSpec.describe 'Tag description Wiki dual writes', type: :request do
   include WikiRecords
   let!(:user) { create_member_user! }
-  let!(:tag) { create(:tag, primary_name: 'description_write') }
+  let!(:tag_name) { create(:tag_name, name: 'description_write') }
+  let(:tag) { create(:tag, primary_tag_name: tag_name) }
   let(:headers) { { 'X-Transfer-Code' => user.inheritance_code } }
 
   def stored_state
-    [Tag, TagName, TagVersion, TagDescription, TagDescriptionVersion].map do |model|
+    [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion,
+     TagName, TagVersion].map do |model|
       model.order(:id).map(&:attributes)
     end
   end
 
-  it 'creates a native description and exposes its version ID as revision ID' do
+  # Fail after a real INSERT/UPDATE, exercising rollback rather than a mock write.
-    expect do
+  def fail_save model
-      post '/wiki', params: { title: tag.name('ja'), body: 'initial' }, headers: headers
+    failure = Class.new(StandardError)
-    end.to change(TagDescription, :count).by(1)
+    callback = ->(_record) { raise failure, 'injected persistence failure' }
-        .and change(TagDescriptionVersion, :count).by(1)
+    model.set_callback(:save, :after, callback)
-    expect(response).to have_http_status(:created)
+    expect { yield }.to raise_error(failure)
-    description = TagDescription.find(json.fetch('id'))
+  ensure
-    expect(description).to have_attributes(tag_id: tag.id, body: 'initial', version_no: 1)
+    model.skip_callback(:save, :after, callback)
-    get "/wiki/#{ description.id }"
-    expect(json.fetch('revision_id')).to eq(current_description_version(description).id)
   end
 
-  context 'with an existing description' do
+  describe 'POST /wiki' do
-    let!(:description) do
+    before { tag }
-      TagDescriptionOperation.create!(
-          Locale.nipponese, tag:, body: 'before', created_by_user: user)
-    end
-    let!(:first_version) { current_description_version(description) }
 
-    def update_description body: 'after', title: tag.name('ja'), base: first_version.id
+    def create_description
-      put "/wiki/#{ description.id }", params: { title:, body:, base_revision_id: base },
+      post '/wiki', params: { title: tag_name.name, body: 'initial', message: 'create' },
-          headers: headers
+           headers: headers
     end
 
-    it 'records a body change without changing resource identity or old history' do
+    it 'creates a description with matching Wiki content and histories' do
-      snapshot = first_version.attributes
+      expect { create_description }
-      expect { update_description }.to change(TagDescriptionVersion, :count).by(1)
+          .to change(WikiPage, :count).by(1)
-      expect(response).to have_http_status(:ok)
+          .and change(WikiRevision, :count).by(1)
-      expect(description.reload).to have_attributes(body: 'after', version_no: 2)
+          .and change(WikiVersion, :count).by(1)
-      expect(first_version.reload.attributes).to eq(snapshot)
+          .and change(TagDescription, :count).by(1)
-      expect(current_description_version(description)).to have_attributes(
+          .and change(TagDescriptionVersion, :count).by(1)
-          body: 'after', event_type: 'update', created_by_user_id: user.id)
+      expect(response).to have_http_status(:created)
+      description = TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
+      expect(description).to have_attributes(body: 'initial', version_no: 1)
+      page = WikiPage.find_by!(tag_name:)
+      expect(page.body).to eq(description.body)
+      expect(page.current_revision.body).to eq(description.body)
+      expect(page.wiki_versions.sole.body).to eq(description.body)
+      expect(json.fetch('id')).to eq(description.id)
+      expect(TagDescriptionVersion.find_by!(tag_id: tag.id, language_code: 'ja'))
+          .to have_attributes(body: 'initial', version_no: 1, created_by_user_id: user.id)
     end
 
-    ['before', "before\r\n\r\n"].each do |body|
+    it 'reuses an existing compatibility page and synchronises its histories' do
-      it "does not write for normalised-equivalent body #{ body.inspect }" do
+      page = Wiki::Commit.create_legacy_content!(
+          tag_name:, body: 'legacy', created_by_user: user)
+      expect { create_description }
+          .to change(WikiPage, :count).by(0)
+          .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)
+      expect(page.reload.body).to eq(description.body)
+      expect(TagDescriptionVersion.find(page.current_revision.id).body).to eq(page.body)
+    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_state = stored_state
-        update_description(body:)
+
-        expect(response).to have_http_status(:ok)
+        post '/wiki', params: { title:, body: 'initial' }, headers: headers
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json).to include('type' => 'validation_error')
         expect(stored_state).to eq(before_state)
       end
     end
 
-    it 'records a title-only edit in Tag history without adding body history' do
+    [false, true].each do |linked|
-      snapshot = description.attributes
+      it "rejects namespaced creation with Tag present: #{ linked }" do
-      expect { update_description(body: 'before', title: 'renamed') }
+        name = create(:tag_name, name: 'Help:frozen')
-          .to change(TagVersion, :count).by(2)
+        create(:tag, primary_tag_name: name) if linked
-          .and change(TagDescriptionVersion, :count).by(0)
-      expect(response).to have_http_status(:ok)
-      expect(tag.reload.name('ja')).to eq('renamed')
-      expect(description.reload.attributes).to eq(snapshot)
-    end
-
-    ['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)
         before_state = stored_state
-        update_description(body:, title: 'conflicting rename')
+        post '/wiki', params: { title: name.name, body: 'legacy' }, headers: headers
-        expect(response).to have_http_status(:conflict)
+        expect(response.status).to be_between(400, 499)
         expect(stored_state).to eq(before_state)
       end
     end
 
-    [TagDescription, TagDescriptionVersion].each do |model|
+    [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion].each do |model|
-      it "rolls back the rename and body after #{ model.name } persistence fails" do
+      it "rolls back new description creation when #{ model.name } persistence fails" do
         before_state = stored_state
-        failure = Class.new(StandardError)
+        aggregate_failures do
-        callback = ->(_record) { raise failure }
+          fail_save(model) { create_description }
-        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
+
+  it 'creates missing compatibility data without writing an ID-colliding Help page' do
+    description = TagDescription.create!(
+        id: 500, tag:, language_code: 'ja', body: 'before', version_no: 1)
+    help = WikiPage.create!(id: description.id,
+                            tag_name: create(:tag_name, name: 'Help:unrelated'),
+                            body: 'unrelated', created_user: user, updated_user: user)
+    Wiki::Commit.legacy_content!(page: help, body: help.body, created_user: user)
+    before_help = help.attributes
+    expect do
+      put "/wiki/#{ description.id }", params: { title: tag_name.name, body: 'after' },
+          headers: headers
+    end.to change(WikiPage, :count).by(1)
+        .and change(WikiRevision, :count).by(1)
+        .and change(WikiVersion, :count).by(1)
+    expect(response).to have_http_status(:ok)
+    expect(description.reload).to have_attributes(id: 500, body: 'after')
+    expect(help.reload.attributes).to eq(before_help)
+    compatibility = WikiPage.find_by!(tag_name:)
+    expect(compatibility.body).to eq(description.body)
+    expect(compatibility.current_revision.body).to eq(description.body)
+  end
+
+  describe 'PUT /wiki/:id' do
+    let!(:page) do
+      tag
+      seed_wiki_page(
+          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(WikiPage, :count).by(0)
+          .and 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)
+    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(WikiPage, :count).by(0)
+          .and 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: 'description_renamed')
+
+      expect(response).to have_http_status(:ok)
+      expect(tag_name.reload.name).to eq('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:)
+
+        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)
+      end
+    end
+  end
 end

backend/spec/requests/tag_descriptions_spec.rb

@@ -1,8 +1,6 @@
 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') }
@@ -11,7 +9,8 @@ RSpec.describe 'Tag description native API', type: :request do
   let(:endpoint) { "/tags/#{ tag.id }/description" }
 
   def stored_state
-    [TagDescription, TagDescriptionVersion, TagName, TagVersion].map do |model|
+    [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion,
+     WikiLine, WikiRevisionLine, TagName, TagVersion].map do |model|
       model.order(:id).map(&:attributes)
     end
   end
@@ -85,7 +84,7 @@ RSpec.describe 'Tag description native API', type: :request do
   describe 'native reads' do
     let!(:description) do
       TagDescription.create!(
-          tag:, language_code: 'ja', body: 'native current',
+          id: tag.id + 1_000_000, 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
@@ -96,14 +95,15 @@ 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, primary_name: 'handle_collision')
+      other_tag = create(:tag, id: description.id, 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)
@@ -153,6 +153,32 @@ 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
@@ -180,24 +206,44 @@ RSpec.describe 'Tag description native API', type: :request do
     context 'without an existing description' do
       before { tag }
 
-
+      it 'creates a description with synchronised Wiki content and histories' do
-      it 'creates native history that is immediately available through the facade' do
+        unrelated = Wiki::Commit.create_legacy_content!(
+            tag_name: create(:tag_name, name: 'Help:unrelated_native_description'),
+            body: 'unrelated body', created_by_user: author)
+        unrelated_state = [unrelated.attributes,
+                           unrelated.wiki_revisions.map(&:attributes),
+                           unrelated.wiki_versions.map(&:attributes)]
         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')
-        expect_current(description)
+        page = WikiPage.find_by!(tag_name: tag.tag_name('ja'))
-        version = current_description_version(description)
+        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(
-            body: 'created natively', version_no: 1, event_type: 'create',
+            tag_id: tag.id, language_code: 'ja', body: description.body,
-            created_by_user_id: editor.id)
+            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)
+        unrelated.reload
+        expect([unrelated.attributes, unrelated.wiki_revisions.map(&:attributes),
+                unrelated.wiki_versions.map(&:attributes)]).to eq(unrelated_state)
+        expect_current(description)
+
         get "/wiki/#{ description.id }"
         expect(response).to have_http_status(:ok)
         expect(json).to include('body' => description.body, 'revision_id' => version.id)
       end
 
-      [TagDescription, TagDescriptionVersion].each do |model|
+      [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion].each do |model|
         it "rolls back native create when #{ model.name } persistence fails" do
           headers
           before_state = stored_state
@@ -212,7 +258,7 @@ RSpec.describe 'Tag description native API', type: :request do
     context 'with an existing description' do
       let!(:page) do
         tag
-        seed_description(tag_name:, body: 'before', created_by_user: author)
+        Wiki::Commit.create_content!(tag_name:, body: 'before', created_by_user: author)
       end
       let!(:description) do
         TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
@@ -222,20 +268,22 @@ 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(TagDescriptionVersion, :count).by(1)
+            .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,
             created_by_user_id: author.id, updated_by_user_id: editor.id)
         expect(page.reload).to have_attributes(body: 'after', version_no: 2)
 
-        revision = current_description_version(page)
+        revision = page.current_revision
         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(description_versions(page).order(:version_no).last.body).to eq(version.body)
+        expect(page.wiki_versions.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)
@@ -246,7 +294,7 @@ 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 = current_description_version(page).id
+          current_revision_id = page.current_revision.id
 
           native_write(body:)
 
@@ -254,11 +302,11 @@ 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(current_description_version(page).id).to eq(current_revision_id)
+          expect(page.current_revision.id).to eq(current_revision_id)
         end
       end
 
-      [TagDescription, TagDescriptionVersion].each do |model|
+      [WikiPage, WikiRevision, WikiVersion, 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

@@ -1,122 +0,0 @@
-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' }
-      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' }
-    expect(response).to have_http_status(:ok)
-    expect(json.fetch('body')).to include('renamed_ainu')
-    get "/wiki/#{ group.id }", params: { locale: 'ain', 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', 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', 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' }
-      expect(response).to have_http_status(:ok)
-      expect(json.fetch('id')).to eq(id)
-      get "#{ path }/exists", params: { locale: 'ain' }
-      expect(response).to have_http_status(:no_content)
-      get '/wiki/search', params: { locale: 'ain', title: "#{ prefix }parent" }
-      expect(json.map { _1.fetch('id') }).to eq([id])
-      put "/wiki/#{ id }", params: {
-          locale: 'ain', title: "#{ prefix }renamed", body: '- ainu_member' }, headers: headers
-      expect(response).to have_http_status(:ok)
-      get "/tag_groups/#{ id }", params: { locale: 'ain' }
-      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', 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', 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' }
-    expect(response).to have_http_status(:ok)
-    body = json.fetch('body')
-    put "/wiki/#{ id }", params: { locale: 'ain', 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', 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

@@ -115,15 +115,6 @@ 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

@@ -7,18 +7,21 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
   let!(:user) { create_member_user! }
   let!(:old_tag) { group_tag('旧タグ') }
   let!(:new_tag) { group_tag('新タグ') }
-  let!(:page) { create_markdown_group('読取り契約', '- 旧タグ') }
+  let!(:page) { legacy_group('読取り契約', '- 旧タグ') }
-  let!(:first_revision) { page.versions.sole }
+  let!(:first_revision) { page.current_revision }
   let!(:last_revision) do
-    parsed = TagGroupMarkdownParser.parse(Locale.nipponese, body: '- 新タグ')
+    Wiki::Commit.legacy_content!(page:, body: '- 新タグ', created_user: user)
-    TagGroupOperation.update!(
-        Locale.nipponese,
-        group: page, name: page.name, actor: user,
-        **parsed.slice(:description, :members, :placements))
-    page.versions.order(:version_no).last
   end
 
-  before { I18n.locale = :ja }
+  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
 
   [:id, :title].each do |lookup|
     context "with #{ lookup } lookup" do
@@ -68,14 +71,36 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
   end
 
   it 'combines Tag Groups and Tag Descriptions without Help in the unfiltered list' do
-    TagDescriptionOperation.create!(
+    help = seed_wiki_page(
-        Locale.nipponese, tag: new_tag, body: 'tag description', created_by_user: user)
+        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)
     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', '新タグ')
+    expect(json.map { _1.fetch('title') }).not_to include(help.title)
   end
 
+  it 'excludes Help when its ID collides with a new group' do
+    help = seed_wiki_page(
+        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('タググループ:別 ID重複')
+    expect(json.map { _1.fetch('title') }).not_to include(help.title)
+
+    get "/wiki/title/#{ CGI.escapeURIComponent(help.title) }"
+    expect(response).to have_http_status(:not_found)
+
+    get '/wiki/changes'
+    expect(response).to have_http_status(:ok)
+    expect(json.map { _1.dig('wiki_page', 'title') }).to include(
+        'タググループ:別 ID重複')
+    expect(json.map { _1.dig('wiki_page', 'title') }).not_to include(help.title)
+  end
 
   it 'finds groups by a partial prefix of their displayed title' do
     get '/wiki', params: { title: 'タググル' }
@@ -87,10 +112,8 @@ 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
-    group = create_markdown_group('旧名称', '正本')
+    old_page = legacy_group('旧名称', '- 旧本文')
-    TagGroupOperation.update!(
+    seed_group(name: '新名称', id: old_page.id, description: '正本')
-        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)
@@ -102,9 +125,12 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
   end
 
   it 'orders mixed resource history by timestamp rather than independent IDs' do
-    TagDescriptionOperation.create!(
+    help = seed_wiki_page(
-        Locale.nipponese, tag: new_tag, body: 'description', created_by_user: user)
+        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)
     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'
@@ -113,6 +139,7 @@ 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).not_to include(help.title)
     expect(titles.index('新タグ')).to be < titles.index('タググループ:読取り契約')
   end
 
@@ -142,6 +169,19 @@ 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 group history but excludes all legacy-only revisions' do
+    extra = Wiki::Commit.legacy_content!(page:, body: 'legacy only', created_user: user)
+    help = seed_wiki_page(
+        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).not_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
@@ -175,5 +215,95 @@ 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
+      seed_wiki_page(
+          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 both new resources sharing a numeric ID without legacy Help' 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_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_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 new resources by title while excluding colliding legacy Help' do
+    help = seed_wiki_page(
+        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', '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
+    without_group_legacy_reads do
+      get "/wiki/title/#{ CGI.escapeURIComponent(help.title) }"
+    end
+    expect(response).to have_http_status(:not_found)
+  end
 end

backend/spec/requests/tag_group_wiki_write_spec.rb

@@ -33,10 +33,11 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
     end
   end
 
-  it 'creates the group, snapshot and native version history' do
+  it 'creates the group, snapshot and matching compatibility histories' do
     expect { create_group }
-        .to change(TagGroup, :count).by(1)
+        .to change(WikiPage, :count).by(1)
-        .and change(TagGroupVersion, :count).by(1)
+        .and change(WikiRevision, :count).by(1)
+        .and change(WikiVersion, :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')
@@ -44,9 +45,10 @@ 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)
-    get group_title_path('新規')
+    page = WikiPage.joins(:tag_name).find_by!(tag_names: { name: 'タググループ:新規' })
-    expect(response).to have_http_status(:ok)
+    expect(page.body).to eq('- 洗澡鹿')
-    expect(json.fetch('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)
   end
 
   it 'keeps repeated placements but only one membership and one snapshot member' do
@@ -106,9 +108,10 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
   end
 
   context 'updating a migrated group' do
-    let!(:page) { create_markdown_group('更新', '- 洗澡鹿') }
+    let!(:page) { legacy_group('更新', '- 洗澡鹿') }
-    let!(:old_revision) { page.versions.order(:version_no).last }
+    let!(:old_revision) { page.current_revision }
 
+    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
@@ -116,9 +119,9 @@ 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 = group_markdown(page)
+        body = page.body
         travel_to(1.hour.from_now) do
-          expect_noop_group_update(group_id: page.id) do
+          expect_noop_group_update(group_id: page.id, page:) do
             repetitions.times do
               update_group(body:)
               expect(response).to have_http_status(:ok)
@@ -131,13 +134,13 @@ 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 = group_markdown(page)
+      body = page.reload.body
-      expect(page.versions.order(:version_no).last.id).not_to eq(old_revision.id)
+      expect(page.current_revision.id).not_to eq(old_revision.id)
 
       travel_to(1.hour.from_now) do
-        expect_noop_group_update(group_id: page.id) do
+        expect_noop_group_update(group_id: page.id, page:) do
           put "/wiki/#{ page.id }",
-              params: { title: "タググループ:#{ page.name }", body:, base_revision_id: old_revision.id },
+              params: { title: page.title, body:, base_revision_id: old_revision.id },
               headers: headers
         end
       end
@@ -145,9 +148,9 @@ 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 = group_markdown(page)
+      body = page.body
       travel_to(1.hour.from_now) do
-        expect_noop_group_update(group_id: page.id) do
+        expect_noop_group_update(group_id: page.id, page:) do
           update_group(body:, request_headers: { 'X-Transfer-Code' => editor.inheritance_code })
         end
       end
@@ -165,11 +168,11 @@ 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 = group_markdown(page)
+      body = page.reload.body
       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) { update_group(body:) }
+        expect_noop_group_update(group_id: page.id, page:) { update_group(body:) }
       end
     end
 
@@ -184,13 +187,16 @@ 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(group_markdown(page).strip).to eq('- 伊地知ニジカ')
+      expect(page.reload.body.strip).to eq('- 伊地知ニジカ')
-      expect(page.versions.count).to eq(2)
+      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)
     end
 
     it 'accepts the current base_revision_id used by the existing frontend' do
       put "/wiki/#{ page.id }",
-          params: { title: "タググループ:#{ page.name }", body: '- 伊地知ニジカ',
+          params: { title: page.title, 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)
@@ -201,12 +207,12 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
       expect(response).to have_http_status(:ok)
 
       put "/wiki/#{ page.id }",
-          params: { title: "タググループ:#{ page.name }", body: '- 洗澡鹿',
+          params: { title: page.title, 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(group_markdown(page).strip).to eq('- 洗澡鹿')
+      expect(page.reload.body.strip).to eq('- 洗澡鹿')
     end
 
     it 'records the editor and update time' do
@@ -251,7 +257,9 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
       let!(:page) do
         next unless operation == :update
 
-        create_markdown_group('更新', '- 洗澡鹿')
+        legacy = legacy_group('更新', '- 洗澡鹿')
+        seed_group(name: '更新', id: legacy.id, members:, placements:)
+        legacy
       end
       let!(:child_id) { seed_group(name: '子グループ', description: '子') }
 
@@ -288,6 +296,7 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
       end
 
       tables = TagGroupRecords::GROUP_TABLES
+      tables += ['wiki_pages', 'wiki_revisions', 'wiki_versions']
       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) }

backend/spec/requests/tag_group_write_integrity_spec.rb

@@ -24,6 +24,11 @@ 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
+    seed_wiki_page(
+        tag_name: create(:tag_name, name: 'Help:既存'), body:, created_by_user: user)
+  end
+
   def expect_no_writes
     before_state = group_state
     yield
@@ -32,28 +37,66 @@ 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')
 
-    it 'renames the group and its facade title through the operation' do
+      expect_no_writes { put_wiki(page.id, title: '古い別名') }
-      page = create_markdown_group('更新', '- 洗澡鹿')
+    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:)
 
       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("タググループ:#{ page.reload.name }").to eq('タググループ:改名')
+      expect(page.reload.title).to eq('タググループ:改名')
-      expect(group_markdown(page)).to eq('- 伊地知ニジカ')
+      expect(page.body).to eq('- 伊地知ニジカ')
     end
 
+    it 'rejects a standalone Help update despite a colliding group ID' 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)
 
+      expect_no_writes { put_wiki(id, title: 'Help:改名', body: 'Help after') }
+
+      expect(page.reload.body).to eq('Help body')
+      expect(page.title).to eq('Help:既存')
+      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 = seed_description(
+      page = Wiki::Commit.create_content!(
           tag_name: tag.tag_name('ja'), body: 'description before', created_by_user: user)
       description = TagDescription.find_by!(tag_id: tag.id)
       id = seed_group(name: '更新', id: description.id, members:, placements:)
@@ -67,22 +110,106 @@ RSpec.describe 'Tag group write integrity', type: :request do
       expect(TagGroup.find(id).attributes).to eq(group_before)
     end
 
-  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')
 
+      expect_no_writes { put_wiki(id, title: 'Help:既存', body: 'Help after') }
 
-  it 'rolls back a facade create when its saved structure cannot be rendered' do
+      expect(page.reload.body).to eq('Help before')
-    allow(TagGroupMarkdownRenderer).to receive(:render)
+      expect(description.reload.body).to eq('description')
-        .and_raise(TagGroupMarkdownRenderer::UnsupportedStructure, 'unsupported')
+      expect(TagGroup.find(id).version_no).to eq(1)
-    expect_no_writes do
+      put_wiki(id, title: '洗澡鹿', body: 'description after')
-      post '/wiki', params: { title: 'タググループ:新規', body: '- 洗澡鹿' }, headers: headers
+      expect(response).to have_http_status(:ok)
+      expect(description.reload.body).to eq('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 before')
+      expect(description.reload.body).to eq('description after')
     end
   end
 
-  it 'rolls back a facade update when its saved structure cannot be rendered' do
+  context 'compatibility synchronisation' do
-    id = seed_group(name: '更新', members:, placements:)
+    it 'synchronises a native rename without modifying an ID-colliding Help page' do
-    allow(TagGroupMarkdownRenderer).to receive(:render)
+      help = create_help('Help before')
-        .and_raise(TagGroupMarkdownRenderer::UnsupportedStructure, 'unsupported')
+      id = seed_group(name: '更新', id: help.id, members:, placements:)
-    expect_no_writes { put_wiki(id, title: 'タググループ:改名') }
+      help_before = help.attributes
+
+      expect do
+        put "/tag_groups/#{ id }", params: native_payload(name: '改名'), headers:, as: :json
+      end.to change(WikiPage, :count).by(1)
+          .and change(WikiRevision, :count).by(1)
+          .and change(WikiVersion, :count).by(1)
+
+      expect(response).to have_http_status(:ok)
+      expect(TagGroup.find(id).name).to eq('改名')
+      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
   end
 
   context 'identifier Markdown' do
@@ -166,10 +293,10 @@ 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 version persistence failure' do
+    it 'rolls back membership removal and placement edits on a late sync failure' do
       new_members = [{ 'tag_id' => tag.id }]
       new_nodes = [{ 'tag_id' => tag.id, 'children' => [] }]
-      expect_atomic_group_write('tag_group_versions') do
+      expect_atomic_group_write('wiki_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

@@ -234,7 +234,8 @@ RSpec.describe 'Tag group native API', type: :request do
 
     context 'compatibility writes for representable structures' do
       let(:group_id) do
-        seed_group(name: '専用API', description: '説明')
+        page = legacy_group('専用API', '説明')
+        seed_group(name: '専用API', id: page.id, description: '説明')
       end
       let(:members) { [{ 'tag_id' => tag.id }, { 'tag_group_id' => child_id }] }
       let(:snapshot_members) do
@@ -251,9 +252,10 @@ 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:) do
+          expect_noop_group_update(group_id:, page:) do
             native_write(:update, unplaced_payload)
           end
         end
@@ -265,18 +267,20 @@ 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(group_markdown(TagGroup.find(group_id)))
+          expect(compatibility_page.body).to include('- 掲載タグ', '- タググループ:子')
-              .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:) do
+              expect_noop_group_update(group_id:, page: compatibility_page) do
                 repetitions.times do
                   native_write(:update, synchronised_payload)
                   expect(response).to have_http_status(:ok)
@@ -288,7 +292,7 @@ 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:) do
+            expect_noop_group_update(group_id:, page: compatibility_page) do
               native_write(:update, synchronised_payload.merge(
                   members: synchronised_payload.fetch(:members).reverse))
             end
@@ -298,7 +302,7 @@ 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:) do
+            expect_noop_group_update(group_id:, page: compatibility_page) do
               put "/tag_groups/#{ group_id }", params: synchronised_payload,
                   headers: { 'X-Transfer-Code' => editor.inheritance_code }, as: :json
             end
@@ -309,7 +313,7 @@ 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(group_markdown(TagGroup.find(group_id))).to eq('- 未掲載タグ')
+          expect(compatibility_page.reload.body).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' => [] }] }
@@ -319,7 +323,7 @@ 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:) do
+            expect_noop_group_update(group_id:, page: compatibility_page) do
               native_write(:update, same_content)
             end
           end
@@ -328,7 +332,7 @@ 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 native history" do
+          it "records a real #{ change } change in both histories" do
             changed = synchronised_payload.deep_dup
             section = changed.fetch(:placements).first
             children = section.fetch('children')
@@ -352,6 +356,11 @@ 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)
@@ -370,17 +379,23 @@ 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(group_markdown(group))
+            expect(json.fetch('body')).to eq(page.body)
           end
         end
       end
 
-      it 'creates native state and its native history' do
+      it 'creates native state and its compatibility histories' do
         expect { native_write(:create) }
-            .to change(TagGroup, :count).by(1)
+            .to change(WikiPage, :count).by(1)
-            .and change(TagGroupVersion, :count).by(1)
+            .and change(WikiRevision, :count).by(1)
+            .and change(WikiVersion, :count).by(1)
         expect(response).to have_http_status(:created)
         expect_group_snapshot(
             json.fetch('id'), number: 1, members: snapshot_members,
@@ -395,13 +410,18 @@ 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')
-          expect(TagGroup.find(id).versions.count).to eq(number)
+          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)
           get group_title_path('構造化')
           expect(response).to have_http_status(:ok)
-          expect(json.fetch('body')).to include('全体の説明', '# 区分', '- 掲載タグ')
+          expect(json.fetch('body')).to eq(page.body)
         end
 
-        TagGroupRecords::GROUP_TABLES
+        (TagGroupRecords::GROUP_TABLES + ['wiki_pages', 'wiki_revisions', 'wiki_versions'])
             .each do |table|
           it "rolls back native #{ operation } after #{ table } writes" do
             expect_atomic_group_write(table) { native_write(operation) }
@@ -409,12 +429,12 @@ RSpec.describe 'Tag group native API', type: :request do
         end
       end
 
-      it 'assigns the next group ID above the existing maximum' do
+      it 'assigns the next group ID from 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(json.fetch('id')).to be >= expected_id
+        expect(json.fetch('id')).to eq(expected_id)
       end
 
       TagGroupRecords::GROUP_TABLES.each do |table|

backend/spec/requests/tag_resource_ids_spec.rb

@@ -1,61 +1,101 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag resource ID allocation', type: :request do
+  include TagGroupRecords
   include WikiRecords
+
   let!(:user) { create_member_user! }
   let(:headers) { { 'X-Transfer-Code' => user.inheritance_code } }
 
-  def create_description name
+  def seed_description id
-    tag = create(:tag, primary_name: name)
+    tag = create(:tag, primary_name: "description_id_#{ id }")
-    post '/wiki', params: { title: tag.name('ja'), body: 'description' }, headers: headers
+    TagDescription.create!(id:, tag:, language_code: 'ja', body: 'existing', version_no: 1)
-    expect(response).to have_http_status(:created)
-    TagDescription.find(json.fetch('id'))
   end
 
-  def create_group name
+  def create_resource resource
-    post '/tag_groups', params: { name:, members: [], placements: [] }, headers:, as: :json
+    if resource == :description
+      tag = create(:tag, primary_name: 'new_description')
+      post '/wiki', params: { title: tag.name('ja'), body: 'new description' }, headers: headers
+    else
+      post '/tag_groups', params: {
+          name: 'new_group', description: 'new group', members: [], placements: [] },
+          headers:, as: :json
+    end
     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, :group].each do |resource|
-    description = create_description('first')
+    it "keeps #{ resource } independent of the Tag and ExternalTag ID space" do
-    group = create_group('second')
+      create(:tag, id: 100)
-    other = create_description('third')
+      create(:external_tag, id: 200)
-    expect([description.id, group.id, other.id]).to eq(
+      seed_description(1)
-        [description.id, group.id, other.id].sort.uniq)
+      seed_group(name: 'shared_space', id: 2)
-    versions = [current_description_version(description), group.versions.sole,
+
-                current_description_version(other)]
+      create_resource(resource)
-    expect(versions.map(&:id)).to eq(versions.map(&:id).sort.uniq)
+
-    expect(versions.map(&:version_no)).to eq([1, 1, 1])
+      expect(json.fetch('id')).to eq(3)
-    [description, group, other].zip(versions).each do |resource, version|
+    end
-      get "/wiki/#{ resource.id }"
+
-      expect(response).to have_http_status(:ok)
+    it "uses the other resource's larger maximum when allocating #{ resource }" do
-      expect(json.fetch('revision_id')).to eq(version.id)
+      seed_description(resource == :description ? 1 : 20)
+      seed_group(name: 'other_space', id: resource == :group ? 1 : 20)
+      create_resource(resource)
+      expect(json.fetch('id')).to eq(21)
+    end
+
+    it "starts #{ resource } at 1 even after previous allocated rows were removed" do
+      expect(TagDescription.count).to eq(0)
+      expect(TagGroup.count).to eq(0)
+      if resource == :description
+        seed_description(100).destroy!
+      else
+        id = seed_group(name: 'removed', id: 100)
+        TagGroup.find(id).destroy!
+      end
+      create_resource(resource)
+      expect(json.fetch('id')).to eq(1)
+    end
+
+    it "allocates #{ resource } above both maxima, preserving legacy overlaps and gaps" do
+      [1, 2, 5].each { seed_description(_1) }
+      [1, 3, 8].each { seed_group(name: "group_#{ _1 }", id: _1) }
+      descriptions = TagDescription.order(:id).map(&:attributes)
+      groups = TagGroup.order(:id).map(&:attributes)
+
+      create_resource(resource)
+
+      expect(json.fetch('id')).to eq(9)
+      expect(TagDescription.where(id: [1, 2, 5]).order(:id).map(&:attributes)).to eq(descriptions)
+      expect(TagGroup.where(id: [1, 3, 8]).order(:id).map(&:attributes)).to eq(groups)
+      expect(TagDescription.exists?(id: 3)).to be(false)
+      expect(TagGroup.exists?(id: 2)).to be(false)
     end
   end
 
-  it 'does not reuse a deleted description ID for a group or vice versa' do
+  it 'preserves group ID and unrelated rows on update' do
-    description = create_description('deleted')
+    id = seed_group(name: 'existing', id: 5, description: 'before')
-    description.destroy!
+    other_id = seed_group(name: 'other', id: 8, description: 'other')
-    group = create_group('deleted group')
+    other = TagGroup.find(other_id).attributes
-    expect(group.id).to be > description.id
+    put "/tag_groups/#{ id }", params: {
-    group.destroy!
+        name: 'renamed', description: 'after', members: [], placements: [] }, headers:, as: :json
-    expect(create_description('replacement').id).to be > group.id
+    expect(response).to have_http_status(:ok)
+    expect(json.fetch('id')).to eq(id)
+    expect(TagGroup.find(id).description).to eq('after')
+    expect(TagGroup.find(other_id).attributes).to eq(other)
+    expect(TagGroup.count).to eq(2)
   end
 
-  it 'preserves resource and old revision identity on an update' do
+  it 'preserves description identity on a compatibility update' do
-    description = create_description('stable')
+    tag = create(:tag, primary_name: 'existing_description')
-    original_resource_id = description.id
+    page = seed_wiki_page(tag_name: tag.tag_name('ja'), body: 'before', created_by_user: user)
-    original = current_description_version(description)
+    description = TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
-    snapshot = original.attributes
+    id = description.id
-    put "/wiki/#{ description.id }",
+    put "/wiki/#{ id }", params: {
-        params: { title: 'stable', body: 'after', base_revision_id: original.id },
+        title: tag.name('ja'), body: 'after', base_revision_id: page.current_revision.id },
         headers: headers
     expect(response).to have_http_status(:ok)
-    expect(description.reload.id).to eq(original_resource_id)
+    expect(description.reload.id).to eq(id)
-    expect(description.reload).to have_attributes(body: 'after', version_no: 2)
+    expect(description.body).to eq('after')
-    expect(original.reload.attributes).to eq(snapshot)
+    expect(TagDescription.count).to eq(1)
-    expect(current_description_version(description).id).to be > original.id
   end
 end

backend/spec/requests/tag_versions_spec.rb

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

backend/spec/requests/tag_wiki_history_integrity_spec.rb

@@ -14,7 +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
-    seed_description(
+    seed_wiki_page(
         tag_name: primary_tag_name_for(tag, 'ja'),
         body:,
         created_by_user: user,
@@ -29,7 +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 = description_versions(wiki_page).map(&:attributes)
+      wiki_history = wiki_page.wiki_versions.map(&:attributes)
 
       expect {
         patch "/tags/#{ tag.id }", params: {
@@ -37,7 +37,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
         }
       }
           .to change(TagVersion, :count).by(2)
-          .and change(TagDescriptionVersion, :count).by(0)
+          .and change(WikiVersion, :count).by(0)
 
       expect(response).to have_http_status(:ok)
 
@@ -45,16 +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.tag.name('ja')).to eq('patch_tag_wiki_after')
+      expect(wiki_page.title).to eq('patch_tag_wiki_after')
 
-      expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
+      expect(wiki_page.wiki_versions.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 = description_versions(wiki_page).count
+      before_wiki_versions = wiki_page.wiki_versions.count
 
       expect {
         patch "/tags/#{ tag.id }", params: {
@@ -70,7 +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(description_versions(wiki_page).count).to eq(before_wiki_versions)
+      expect(wiki_page.wiki_versions.count).to eq(before_wiki_versions)
     end
   end
 
@@ -78,7 +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 = description_versions(wiki_page).map(&:attributes)
+      wiki_history = wiki_page.wiki_versions.map(&:attributes)
 
       expect {
         put "/tags/#{ tag.id }", params: {
@@ -90,7 +90,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
         }
       }
           .to change(TagVersion, :count).by(2)
-          .and change(TagDescriptionVersion, :count).by(0)
+          .and change(WikiVersion, :count).by(0)
 
       expect(response).to have_http_status(:ok)
 
@@ -98,16 +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.tag.name('ja')).to eq('put_tag_wiki_after')
+      expect(wiki_page.title).to eq('put_tag_wiki_after')
 
-      expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
+      expect(wiki_page.wiki_versions.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 = description_versions(wiki_page).count
+      before_wiki_versions = wiki_page.wiki_versions.count
 
       expect {
         put "/tags/#{ tag.id }", params: {
@@ -127,14 +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(description_versions(wiki_page).count).to eq(before_wiki_versions)
+      expect(wiki_page.wiki_versions.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 = description_versions(wiki_page).count
+      before_wiki_versions = wiki_page.wiki_versions.count
 
       expect {
         put "/tags/#{ tag.id }", params: {
@@ -148,7 +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(description_versions(wiki_page).count).to eq(before_wiki_versions)
+      expect(wiki_page.reload.wiki_versions.count).to eq(before_wiki_versions)
     end
   end
 end

backend/spec/requests/tags_spec.rb

@@ -2,7 +2,6 @@ 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:) }
@@ -746,13 +745,13 @@ 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 =
-            seed_description(
+            Wiki::Commit.create_content!(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'wiki body before',
                 created_by_user: member_user,
                 message: 'init')
 
-        wiki_history = description_versions(wiki_page).map(&:attributes)
+        wiki_history = wiki_page.wiki_versions.map(&:attributes)
 
         expect {
           patch "/tags/#{ tag.id }", params: {
@@ -760,23 +759,23 @@ RSpec.describe 'Tags API', type: :request do
           }
         }
             .to change(TagVersion, :count).by(2)
-            .and change(TagDescriptionVersion, :count).by(0)
+            .and change(WikiVersion, :count).by(0)
 
         expect(response).to have_http_status(:ok)
 
-        expect(wiki_page.reload.tag.name('ja')).to eq('patch_wiki_renamed_tag')
+        expect(wiki_page.reload.title).to eq('patch_wiki_renamed_tag')
-        expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
+        expect(wiki_page.wiki_versions.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 =
-            seed_description(
+            Wiki::Commit.create_content!(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'wiki body before',
                 created_by_user: member_user,
                 message: 'init')
 
-        before_wiki_version_count = description_versions(wiki_page).count
+        before_wiki_version_count = wiki_page.reload.wiki_versions.count
 
         expect {
           patch "/tags/#{ tag.id }", params: {
@@ -785,7 +784,7 @@ RSpec.describe 'Tags API', type: :request do
         }.to change(TagVersion, :count).by(2)
 
         expect(response).to have_http_status(:ok)
-        expect(description_versions(wiki_page).count).to eq(before_wiki_version_count)
+        expect(wiki_page.reload.wiki_versions.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
@@ -816,7 +815,7 @@ 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 =
-            seed_description(
+            Wiki::Commit.create_content!(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'patch collision wiki',
                 created_by_user: member_user,
@@ -832,7 +831,7 @@ 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.tag_name('ja')).to eq(primary_tag_name_for(tag, 'ja'))
+        expect(wiki_page.reload.tag_name).to eq(primary_tag_name_for(tag, 'ja'))
       end
 
       it 'system tag の name は変更できない' do
@@ -1210,7 +1209,7 @@ 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(TagName.exists?(alias_tn.id)).to be(false)
+        expect(alias_tn.reload.tag_id).to be_nil
 
         expect(TagName.where(tag_id: tag.parents.select(:id),
                              language_code: 'ja', primary_flg: true).pluck(:name))
@@ -1395,17 +1394,20 @@ 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 =
-            seed_description(
+            Wiki::Commit.create_content!(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'wiki body before',
                 created_by_user: member_user,
                 message: 'init')
 
-        TagDescriptionOperation.update!(
+        Wiki::Commit.content!(
-            Locale.nipponese, tag: wiki_page.tag, body: 'wiki body before',
+          page: wiki_page,
-            updated_by_user: member_user, message: 'init')
+          body: 'wiki body before',
+          created_user: member_user,
+          message: 'init'
+        )
 
-        wiki_history = description_versions(wiki_page).map(&:attributes)
+        wiki_history = wiki_page.wiki_versions.map(&:attributes)
 
         expect {
           put "/tags/#{ tag.id }", params: {
@@ -1417,22 +1419,22 @@ RSpec.describe 'Tags API', type: :request do
           }
         }
             .to change(TagVersion, :count).by(2)
-            .and change(TagDescriptionVersion, :count).by(0)
+            .and change(WikiVersion, :count).by(0)
 
         expect(response).to have_http_status(:ok)
 
-        expect(wiki_page.reload.tag.name('ja')).to eq('put_wiki_version_tag')
+        expect(wiki_page.reload.title).to eq('put_wiki_version_tag')
-        expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
+        expect(wiki_page.wiki_versions.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 =
-            seed_description(
+            Wiki::Commit.create_content!(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'wiki body before',
                 created_by_user: member_user,
                 message: 'init')
-        wiki_history = description_versions(wiki_page).map(&:attributes)
+        wiki_history = wiki_page.wiki_versions.map(&:attributes)
 
         expect {
           put "/tags/#{ tag.id }", params: {
@@ -1452,19 +1454,20 @@ RSpec.describe 'Tags API', type: :request do
           }
         }
             .to change(TagVersion, :count).by(3)
-            .and change(TagDescriptionVersion, :count).by(0)
+            .and change(WikiVersion, :count).by(0)
 
         expect(response).to have_http_status(:ok)
 
         tag.reload
 
-        expect(wiki_page.reload.tag.tag_name('ja')).to eq(primary_tag_name_for(tag, 'ja'))
+        expect(wiki_page.reload.tag_name).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').wiki_page)
+            .to be_nil
         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.tag.name('ja')).to eq('spec_tag')
+        expect(wiki_page.title).to eq('spec_tag')
-        expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
+        expect(wiki_page.wiki_versions.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
@@ -1517,7 +1520,7 @@ RSpec.describe 'Tags API', type: :request do
             name: 'put_alias_collision_name',
             tag: old_owner)
         wiki_page =
-            seed_description(
+            Wiki::Commit.create_content!(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'put collision wiki',
                 created_by_user: member_user,
@@ -1551,7 +1554,7 @@ 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.tag_name('ja')).to eq(primary_tag_name_for(tag, 'ja'))
+        expect(wiki_page.reload.tag_name).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
@@ -1576,13 +1579,13 @@ 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 =
-            seed_description(
+            Wiki::Commit.create_content!(
                 tag_name: primary_tag_name_for(tag, 'ja'),
                 body: 'wiki body before',
                 created_by_user: member_user,
                 message: 'init')
 
-        wiki_history = description_versions(wiki_page).map(&:attributes)
+        wiki_history = wiki_page.wiki_versions.map(&:attributes)
 
         expect {
           put "/tags/#{ tag.id }", params: {
@@ -1594,12 +1597,12 @@ RSpec.describe 'Tags API', type: :request do
           }
         }
             .to change(TagVersion, :count).by(2)
-            .and change(TagDescriptionVersion, :count).by(0)
+            .and change(WikiVersion, :count).by(0)
 
         expect(response).to have_http_status(:ok)
 
-        expect(wiki_page.reload.tag.name('ja')).to eq('put_wiki_renamed_tag')
+        expect(wiki_page.reload.title).to eq('put_wiki_renamed_tag')
-        expect(description_versions(wiki_page).reload.map(&:attributes)).to eq(wiki_history)
+        expect(wiki_page.wiki_versions.reload.map(&:attributes)).to eq(wiki_history)
       end
     end
   end

backend/spec/requests/wiki_conflict_spec.rb

@@ -10,19 +10,18 @@ RSpec.describe 'Wiki conflict handling', type: :request do
 
   it 'returns 409 when base_revision_id is stale' do
     page =
-        seed_description(
+        seed_wiki_page(
             tag_name: create(:tag, primary_name: 'wiki_conflict_request').tag_name('ja'),
             body: 'first',
             created_by_user: user,
             message: 'init')
 
-    stale_id = current_description_version(page).id
+    stale_id = page.current_revision.id
 
-    TagDescriptionOperation.update!(
+    Wiki::Commit.content!(
-        Locale.nipponese,
+        page:,
-        tag: page.tag,
         body: 'second',
-        updated_by_user: user,
+        created_user: user,
         message: 'other edit',
         base_revision_id: stale_id)
 
@@ -37,6 +36,6 @@ RSpec.describe 'Wiki conflict handling', type: :request do
 
     page.reload
     expect(page.body).to eq('second')
-    expect(current_description_version(page)).to have_attributes(body: 'second', version_no: 2)
+    expect(page.current_revision.message).to eq('other edit')
   end
 end

backend/spec/requests/wiki_creation_freeze_spec.rb

@@ -7,11 +7,27 @@ RSpec.describe 'Wiki creation freeze', type: :request do
   let!(:user) { create_member_user! }
   let(:headers) { { 'X-Transfer-Code' => user.inheritance_code } }
 
+  it 'creates missing compatibility history when updating an independent group' do
+    id = seed_group(name: 'independent', description: 'before')
+    expect do
+      put "/tag_groups/#{ id }", params: {
+          name: 'independent', description: 'after', members: [], placements: [] },
+          headers:, as: :json
+    end.to change(WikiPage, :count).by(1)
+        .and change(WikiRevision, :count).by(1)
+        .and change(WikiVersion, :count).by(1)
+    expect(response).to have_http_status(:ok)
+    expect(TagGroup.find(id).description).to eq('after')
+    page = WikiPage.joins(:tag_name).find_by!(tag_names: { name: 'タググループ:independent' })
+    expect(page.body).to include('after')
+    expect(page.current_revision.body).to eq(page.body)
+    expect(page.wiki_versions.sole.body).to eq(page.body)
+  end
 
   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)
+      seed_wiki_page(tag_name: tag.tag_name('ja'), body: 'before', created_by_user: user)
     end
 
     [nil, :guest, :banned].each do |role|

backend/spec/requests/wiki_history_integrity_spec.rb

@@ -0,0 +1,170 @@
+require 'cgi'
+require 'rails_helper'
+
+RSpec.describe 'Wiki history integrity', type: :request do
+  include WikiRecords
+  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
+    seed_wiki_page(
+        tag_name: create(:tag, primary_name: title).tag_name('ja'),
+        body:,
+        created_by_user: user,
+        message:)
+  end
+
+  describe 'POST /wiki' do
+    it 'rejects frozen creation without partial page or history' do
+      expect do
+        post '/wiki', params: { title: 'Help:wiki_history_create_atomic', body: 'initial' },
+             headers: auth_headers(user)
+      end.to change(WikiPage, :count).by(0)
+          .and change(WikiRevision, :count).by(0)
+          .and change(WikiVersion, :count).by(0)
+      expect(response.status).to be_between(400, 499)
+    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 'rejects frozen creation without modifying an existing page or history' do
+      create_wiki_page(title: 'Help:wiki_history_duplicate_title', body: 'first')
+
+      expect do
+        post '/wiki',
+             params: { title: 'Help:wiki_history_duplicate_title',
+                       body: 'second', message: 'duplicate' },
+             headers: auth_headers(user)
+      end.to change(WikiPage, :count).by(0)
+          .and change(WikiRevision, :count).by(0)
+          .and change(WikiVersion, :count).by(0)
+
+      expect(response.status).to be_between(400, 499)
+      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

@@ -28,15 +28,15 @@ RSpec.describe 'Wiki resource ordering', type: :request do
   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',
+    TagDescription.create!(id: 51, tag:, language_code: 'ja', body: 'current',
                            version_no: 1, updated_at: time)
-    group = TagGroup.find(seed_group(name: 'tied', id: description.id))
+    group = TagGroup.find(seed_group(name: 'tied', id: 51))
     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]])
+          .to eq([['tag_description', 51], ['tag_group', 51]])
     end
   end
 end

backend/spec/requests/wiki_locale_spec.rb

@@ -1,158 +0,0 @@
-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' }
-      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', 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' }
-      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' }
-      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' }
-    expect(response).to have_http_status(:no_content)
-    get '/wiki/title/japanese_title/exists', params: { locale: 'ain' }
-    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', 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', id: japanese.id }
-    expect(response).to have_http_status(:ok)
-    expect(json).to eq([])
-    get '/wiki/changes', params: { locale: 'ain' }
-    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', 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', title: 'other_ainu', body: 'created' },
-               headers: headers
-        else
-          put "/tags/#{ other.id }/description", params: { locale: 'ain', 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', 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' }
-    expect(json).to include('body' => 'native edit', 'revision_id' => second.id)
-
-    put "/wiki/#{ ainu.id }", params: {
-        locale: 'ain', 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' }
-    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', 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', 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', 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', from: current_description_version(japanese).id }
-    expect(response).to have_http_status(:not_found)
-  end
-end

backend/spec/requests/wiki_spec.rb

@@ -19,7 +19,7 @@ RSpec.describe 'Wiki API', type: :request do
         deprecated_at: Time.zone.local(2026, 6, 1))
   end
   let!(:page) do
-    seed_description(
+    seed_wiki_page(
         tag_name: tn,
         body: 'init',
         created_by_user: user,
@@ -113,9 +113,9 @@ RSpec.describe 'Wiki API', type: :request do
       it "rejects frozen creation of #{ title } without history writes" do
         expect do
           post endpoint, params: { title:, body: 'initial' }, headers: auth_headers(member)
-        end.to change(TagDescription, :count).by(0)
+        end.to change(WikiPage, :count).by(0)
-            .and change(TagDescriptionVersion, :count).by(0)
+            .and change(WikiRevision, :count).by(0)
-
+            .and change(WikiVersion, :count).by(0)
         expect(response.status).to be_between(400, 499)
       end
     end
@@ -132,7 +132,7 @@ RSpec.describe 'Wiki API', type: :request do
     let!(:test_tag_name) { create(:tag, primary_name: 'TestPage').tag_name('ja') }
 
     let!(:page) do
-      seed_description(
+      seed_wiki_page(
           tag_name: test_tag_name,
           body: "a\nb",
           created_by_user: member,
@@ -166,7 +166,7 @@ RSpec.describe 'Wiki API', type: :request do
 
     context 'when success' do
       it 'creates new revision and returns 200' do
-        current_id = description_versions(page).maximum(:id)
+        current_id = page.wiki_revisions.maximum(:id)
 
         expect do
           put "/wiki/#{page.id}",
@@ -174,22 +174,26 @@ RSpec.describe 'Wiki API', type: :request do
                         base_revision_id: current_id },
               headers: auth_headers(member)
         end
-            .to change(TagDescriptionVersion, :count).by(1)
+            .to change(WikiRevision, :count).by(1)
+            .and change(WikiVersion, :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 = current_description_version(page)
+        rev = page.current_revision
+        expect(rev).to be_content
+        expect(rev.message).to eq('edit')
         expect(page.body).to eq("x\ny")
-        expect(rev.version_no).to eq(2)
+        expect(rev.base_revision_id).to eq(current_id)
       end
 
       it 'wiki body だけを変更しても tag version は作成しない' do
@@ -202,13 +206,13 @@ RSpec.describe 'Wiki API', type: :request do
             created_by_user: member)
 
         linked_page =
-            seed_description(
+            seed_wiki_page(
                 tag_name: linked_tag_name,
                 body: 'before',
                 created_by_user: member,
                 message: 'init')
 
-        current_id = current_description_version(linked_page).id
+        current_id = linked_page.current_revision.id
         before_count = linked_tag.reload.tag_versions.count
 
         expect {
@@ -221,8 +225,8 @@ RSpec.describe 'Wiki API', type: :request do
               },
               headers: auth_headers(member)
         }
-            .to change(TagDescriptionVersion, :count).by(1)
+            .to change(WikiRevision, :count).by(1)
-
+            .and change(WikiVersion, :count).by(1)
 
         expect(response).to have_http_status(:ok)
         expect(linked_tag.reload.tag_versions.count).to eq(before_count)
@@ -232,12 +236,10 @@ 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
-        TagDescriptionOperation.update!(
+        Wiki::Commit.content!(page: page, body: "zzz", created_user: member, message: 'other edit')
-            Locale.nipponese, tag: page.tag, body: 'zzz',
-            updated_by_user: member, message: 'other edit')
         page.reload
 
-        stale_id = description_versions(page).order(:id).first.id # わざと古い id
+        stale_id = page.wiki_revisions.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)
@@ -279,13 +281,13 @@ RSpec.describe 'Wiki API', type: :request do
   describe 'GET /wiki/search' do
     before do
       search_tag = create(:tag, primary_name: 'spec_wiki_title_2')
-      seed_description(
+      seed_wiki_page(
           tag_name: search_tag.tag_name('ja'),
           body: 'search body 2',
           created_by_user: user,
           message: 'init')
 
-      seed_description(
+      seed_wiki_page(
           tag_name: create(:tag_name, name: 'unrelated_title'),
           body: 'unrelated body',
           created_by_user: user,
@@ -316,15 +318,13 @@ RSpec.describe 'Wiki API', type: :request do
 
   describe 'GET /wiki/changes' do
     let!(:rev1) do
-      TagDescriptionOperation.update!(
+      Wiki::Commit.content!(page: page, body: "a\nb", created_user: user, message: 'r1')
-          Locale.nipponese, tag: page.tag, body: "a\nb", updated_by_user: user, message: 'r1')
+      page.current_revision
-      current_description_version(page)
     end
 
     let!(:rev2) do
-      TagDescriptionOperation.update!(
+      Wiki::Commit.content!(page: page, body: "a\nc", created_user: user, message: 'r2')
-          Locale.nipponese, tag: page.tag, body: "a\nc", updated_by_user: user, message: 'r2')
+      page.current_revision
-      current_description_version(page)
     end
 
     it 'returns latest revisions (optionally filtered by page id)' do
@@ -358,9 +358,12 @@ 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: Version のない TagDescription を直接作る
+      # 異常データ: revision 無し WikiPage を直接作る
-      p2 = TagDescription.create!(
+      p2 = WikiPage.create!(
-          tag: tn2.tag, language_code: 'ja', body: 'init', version_no: 1)
+          tag_name: tn2,
+          body: 'init',
+          created_user: user,
+          updated_user: user)
 
       get "/wiki/changes?id=#{p2.id}"
       expect(response).to have_http_status(:ok)
@@ -396,15 +399,13 @@ RSpec.describe 'Wiki API', type: :request do
 
   describe 'GET /wiki/:id/diff' do
     let!(:rev_a) do
-      TagDescriptionOperation.update!(
+      Wiki::Commit.content!(page: page, body: "a\nb\nc", created_user: user, message: 'A')
-          Locale.nipponese, tag: page.tag, body: "a\nb\nc", updated_by_user: user, message: 'A')
+      page.current_revision
-      current_description_version(page)
     end
 
     let!(:rev_b) do
-      TagDescriptionOperation.update!(
+      Wiki::Commit.content!(page: page, body: "a\nx\nc", created_user: user, message: 'B')
-          Locale.nipponese, tag: page.tag, body: "a\nx\nc", updated_by_user: user, message: 'B')
+      page.current_revision
-      current_description_version(page)
     end
 
     it 'returns diff json between revisions' do
@@ -430,23 +431,44 @@ 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(current_description_version(page).id)
+      expect(json['newer_revision_id']).to eq(page.current_revision.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 =
+          seed_wiki_page(
+              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 =
-        seed_description(
+        seed_wiki_page(
             tag_name: linked_tag_name,
             body: 'before',
             created_by_user: user,
             message: 'init')
 
-    current_id = current_description_version(linked_page).id
+    current_id = linked_page.current_revision.id
 
     expect {
       put "/wiki/#{ linked_page.id }",
@@ -458,7 +480,8 @@ RSpec.describe 'Wiki API', type: :request do
           },
           headers: auth_headers(user)
     }
-        .to change(TagDescriptionVersion, :count).by(1)
+        .to change(WikiRevision, :count).by(1)
+        .and change(WikiVersion, :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

@@ -9,7 +9,7 @@ RSpec.describe 'Wiki title collision', type: :request do
   end
 
   def create_wiki_page title:, body:
-    seed_description(
+    seed_wiki_page(
         tag_name: create(:tag_name, name: title),
         body:,
         created_by_user: user,
@@ -20,9 +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 = description_versions(source).count
+    source_revision_count = source.wiki_revisions.count
-    source_version_count = description_versions(source).count
+    source_version_count = source.wiki_versions.count
-    old_title = source.tag.reload.name('ja')
+    old_title = source.title
     old_body = source.body
 
     put "/wiki/#{ source.id }",
@@ -30,7 +30,7 @@ RSpec.describe 'Wiki title collision', type: :request do
           title: 'wiki_collision_target',
           body: 'new body',
           message: 'rename collision',
-          base_revision_id: current_description_version(source).id,
+          base_revision_id: source.current_revision.id,
         },
         headers: auth_headers(user)
 
@@ -38,10 +38,10 @@ RSpec.describe 'Wiki title collision', type: :request do
 
     source.reload
 
-    expect(source.tag.reload.name('ja')).to eq(old_title)
+    expect(source.title).to eq(old_title)
     expect(source.body).to eq(old_body)
-    expect(description_versions(source).count).to eq(source_revision_count)
+    expect(source.wiki_revisions.count).to eq(source_revision_count)
-    expect(description_versions(source).count).to eq(source_version_count)
+    expect(source.wiki_versions.count).to eq(source_version_count)
   end
 
   it 'rejects frozen creation with an existing title without adding history' do
@@ -52,8 +52,9 @@ RSpec.describe 'Wiki title collision', type: :request do
            params: { title: 'Help:wiki_collision_create', body: 'new body',
                      message: 'duplicate create' },
            headers: auth_headers(user)
-    end.to change(TagDescription, :count).by(0)
+    end.to change(WikiPage, :count).by(0)
-        .and change(TagDescriptionVersion, :count).by(0)
+        .and change(WikiRevision, :count).by(0)
+        .and change(WikiVersion, :count).by(0)
 
     expect(response.status).to be_between(400, 499)
   end

backend/spec/requests/wiki_unmigrated_contract_spec.rb

@@ -1,25 +1,78 @@
 require 'rails_helper'
 
-RSpec.describe 'Removed standalone Wiki resources', type: :request do
+RSpec.describe 'Unmigrated Wiki compatibility', type: :request do
-  include TagGroupRecords
+  include WikiRecords
-  let(:user) { create_member_user! }
+  let!(:user) { create_member_user! }
+  let!(:tag_name) { create(:tag_name, name: 'Help_contract') }
+  let!(:page) do
+    seed_wiki_page(tag_name:, body: 'before', created_by_user: user)
+  end
+  let!(:first_revision) { page.current_revision }
+  let!(:last_revision) do
+    Wiki::Commit.legacy_content!(page:, body: 'after', created_user: user,
+                                 message: 'legacy edit', base_revision_id: first_revision.id)
+  end
 
-  ['Help:old', 'ヘルプ:旧ページ'].each do |title|
+  before { expect(TagDescription.exists?(id: page.id)).to be(false) }
-    it "does not resolve #{ title } as a Wiki resource" do
+
-      path = "/wiki/title/#{ CGI.escapeURIComponent(title) }"
+  it 'rejects standalone updates even after a Tag is linked to the legacy page' do
-      without_group_legacy_reads { get path }
+    create(:tag, primary_tag_name: tag_name)
-      expect(response).to have_http_status(:not_found)
+    original = page.reload.attributes
-      get "#{ path }/exists"
+
-      expect(response).to have_http_status(:not_found)
+    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(0)
+        .and change(WikiVersion, :count).by(0)
+        .and change(TagDescription, :count).by(0)
+        .and change(TagDescriptionVersion, :count).by(0)
+
+    expect(response).to have_http_status(:unprocessable_entity)
+    expect(page.reload.attributes).to eq(original)
+    expect(page.current_revision).to have_attributes(message: 'legacy edit')
+  end
+
+  include TagGroupRecords
+
+  [:id, :title].each do |lookup|
+    [nil, :historical].each do |edition|
+      it "rejects legacy #{ lookup } #{ edition || 'current' } without legacy SELECTs" do
+        path = lookup == :id ? "/wiki/#{ page.id }" : "/wiki/title/#{ tag_name.name }"
+        params = edition ? { version: first_revision.id } : { }
+        without_group_legacy_reads { get path, params: }
+        expect(response).to have_http_status(:not_found)
+      end
     end
 
-    it "rejects standalone creation of #{ title } without writes" do
+    it "does not recognise legacy #{ lookup } existence" do
-      user
+      path = lookup == :id ? "/wiki/#{ page.id }" : "/wiki/title/#{ tag_name.name }"
-      before_state = group_state
+      without_group_legacy_reads { get "#{ path }/exists" }
-      post '/wiki', params: { title:, body: 'body' },
+      expect(response).to have_http_status(:not_found)
-           headers: { 'X-Transfer-Code' => user.inheritance_code }
+    end
-      expect(response).to have_http_status(:unprocessable_entity)
+  end
-      expect(group_state).to eq(before_state)
+
+  ['/wiki', '/wiki/search', '/wiki/changes'].each do |path|
+    it "excludes unmigrated content from #{ path } without legacy SELECTs" do
+      without_group_legacy_reads { get path }
+      expect(response).to have_http_status(:ok)
+      expect(json).to eq([])
+    end
+  end
+
+  it 'returns empty scoped history without legacy SELECTs' do
+    without_group_legacy_reads { get '/wiki/changes', params: { id: page.id } }
+    expect(response).to have_http_status(:ok)
+    expect(json).to eq([])
+  end
+
+  [false, true].each do |explicit|
+    it "rejects legacy diff with #{ explicit ? 'explicit' : 'current' } target" do
+      params = { from: first_revision.id }
+      params[:to] = last_revision.id if explicit
+      without_group_legacy_reads { get "/wiki/#{ page.id }/diff", params: }
+      expect(response).to have_http_status(:not_found)
     end
   end
 end

backend/spec/services/shared_resource_id_allocator_mysql_spec.rb

@@ -9,9 +9,9 @@ RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
     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")
+    @names = [0, 1].map { create(:tag_name, name: "#{ @prefix }_#{ _1 }") }
-    @group = TagGroup.create!(name: "#{ @prefix }_owner", version_no: 1)
+    @tag = Tag.create!(tag_name_id: @names.first.id, category: :general)
-    @tag_ids = Queue.new
+    @names.first.update!(tag_id: @tag.id)
     @threads = []
     @release = Queue.new
   end
@@ -23,21 +23,17 @@ RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
         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 = []
+      if @names
-      ids << @tag_ids.pop until @tag_ids.empty? if @tag_ids
+        ids = @names.map(&:id)
-      ids << @tag.id if @tag
+        TagName.where(id: ids).update_all(tag_id: nil)
-      TagName.where(tag_id: ids).delete_all
+        Tag.where(tag_name_id: ids).delete_all
-      Tag.where(id: ids).delete_all
+        TagName.where(id: ids).delete_all
+      end
     end
   end
 
@@ -55,19 +51,11 @@ RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
   def create_resource kind
     case kind
     when :tag
-      Tag.create!(category: :general).tap { @tag_ids << _1.id }
+      Tag.create!(tag_name_id: @names.last.id, category: :general)
     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
@@ -100,8 +88,7 @@ RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
     thread.value
   end
 
-  { tags: [:external, :tag], wiki: [:description, :group],
+  { tags: [:external, :tag], wiki: [:description, :group] }.each do |space, kinds|
-    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)
@@ -109,7 +96,7 @@ RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
           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
+        expect(first_id).to eq(maxima.max + 1)
         connection = ApplicationRecord.connection
         quoted_lock = connection.quote(lock_name)
         expect(connection.select_value("SELECT IS_USED_LOCK(#{ quoted_lock })").to_i)
@@ -123,7 +110,7 @@ RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
         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(result(second)).to eq(rollback ? first_id : first_id + 1)
         expect(connection.select_value("SELECT IS_FREE_LOCK(#{ quoted_lock })").to_i).to eq(1)
       end
     end

backend/spec/services/shared_resource_id_allocator_spec.rb

@@ -1,103 +1,6 @@
 require 'rails_helper'
 
 RSpec.describe SharedResourceIdAllocator do
-  let(:tag) { create(:tag) }
-
-  def resource table, id: nil, number: 1
-    case table
-    when 'tags'
-      Tag.new(id:, category: :general)
-    when 'external_tags'
-      ExternalTag.new(id:, platform: :nico, name: "external #{ number }")
-    when 'tag_descriptions'
-      TagDescription.new(id:, tag:, language_code: 'ja', body: 'body', version_no: number)
-    when 'tag_groups'
-      TagGroup.new(id:, name: "group #{ number }", version_no: number)
-    when 'tag_description_versions'
-      TagDescriptionVersion.new(
-          id:, tag_id: tag.id, language_code: 'ja', body: 'body', version_no: number,
-          event_type: 'create', created_at: Time.current)
-    when 'tag_group_versions'
-      TagGroupVersion.new(
-          id:, tag_group_id: group.id, name: group.name, version_no: number,
-          event_type: 'create', members: [], placements: [], created_at: Time.current)
-    end
-  end
-
-  let(:group) { TagGroup.create!(name: 'history owner', version_no: 1) }
-
-  described_class::SPACES.each do |space, tables|
-    tables.permutation.each do |first_table, second_table|
-      it "keeps deleted #{ first_table } IDs reserved for #{ second_table }" do
-        first = resource(first_table)
-        first.save!
-        used_id = first.id
-        first.class.where(id: first.id).delete_all
-        second = resource(second_table)
-        second.save!
-        expect(second.id).to be > used_id
-      end
-
-      it "advances #{ space } after an explicit INSERT in #{ first_table }" do
-        first = resource(first_table)
-        first.save!
-        high = first.id + 100
-        explicit = resource(first_table, id: high, number: 2)
-        first.class.where(id: first.id).delete_all
-        explicit.save!
-        explicit.class.where(id: explicit.id).delete_all
-        second = resource(second_table)
-        second.save!
-        expect(second.id).to be > high
-      end
-    end
-
-    it "allows explicit overlapping Id.s in #{ space }" do
-      first = resource(tables.first)
-      first.save!
-
-      second = resource(tables.last, id: first.id)
-      second.save!
-
-      expect(second.id).to eq(first.id)
-      expect(first.reload.id).to eq(first.id)
-    end
-
-    it "preserves historical #{ space } overlaps without repairing them" do
-      first = resource(tables.first)
-      first.save!
-      second = resource(tables.last)
-      second.save!
-      second.class.where(id: second.id).update_all(id: first.id)
-      second = second.class.find(first.id)
-      snapshots = [first.reload.attributes, second.reload.attributes]
-      next_record = resource(tables.last, number: 2)
-      next_record.save!
-      expect(next_record.id).to be > first.id
-      expect(first.reload.attributes).to eq(snapshots.first)
-      expect(second.reload.attributes).to eq(snapshots.last)
-    end
-  end
-
-  it 'reserves a Tag ID referenced only by remaining description history' do
-    high = [Tag.maximum(:id).to_i, ExternalTag.maximum(:id).to_i].max + 1000
-    TagDescriptionVersion.create!(
-        tag_id: high, language_code: 'ja', version_no: 1, body: 'history',
-        event_type: 'create', created_at: Time.current)
-    expect(create(:tag).id).to be > high
-    expect(create(:external_tag).id).to be > high
-  end
-
-  it 'reserves a group ID referenced only by remaining group history' do
-    high = [TagGroup.maximum(:id).to_i, TagDescription.maximum(:id).to_i].max + 1000
-    version = resource('tag_group_versions')
-    version.save!
-    TagGroupVersion.where(id: version.id).update_all(tag_group_id: high)
-    expect(TagGroup.create!(name: 'replacement', version_no: 1).id).to be > high
-  end
-end
-
-RSpec.describe SharedResourceIdAllocator, 'lock lifecycle' do
   let(:record) { build(:external_tag) }
   let(:connection) { double('connection') }
   let(:transaction) { double('transaction', open?: true) }
@@ -108,14 +11,6 @@ RSpec.describe SharedResourceIdAllocator, 'lock lifecycle' do
     config = double('config', database: 'test_shared_ids')
     allow(connection).to receive_message_chain(:pool, :db_config).and_return(config)
     allow(connection).to receive(:quote) { "'#{ _1 }'" }
-    allow(connection).to receive(:quote_column_name) { "`#{ _1 }`" }
-    allow(connection).to receive(:execute) { sql << _1 }
-    allow(connection).to receive(:select_all) do |statement|
-      tables = described_class::SPACES.values.flatten.select do |table|
-        statement.include?("'#{ table }'")
-      end
-      tables.map { { 'TABLE_NAME' => _1, 'ENGINE' => 'InnoDB', 'AUTO_INCREMENT' => 9 } }
-    end
     allow(connection).to receive(:quote_table_name) { "`#{ _1 }`" }
     allow(connection).to receive(:select_value) do |statement|
       sql << statement
@@ -140,6 +35,7 @@ RSpec.describe SharedResourceIdAllocator, 'lock lifecycle' do
       described_class.assign!(record)
       expect(record.id).to eq(9)
       expect(sql.grep(/RELEASE_LOCK/)).to be_empty
+      expect(sql.grep(/FOR UPDATE/).size).to eq(2)
       callbacks.fetch(event).call
       expect(sql.grep(/RELEASE_LOCK/).size).to eq(1)
     end
@@ -153,22 +49,22 @@ RSpec.describe SharedResourceIdAllocator, 'lock lifecycle' do
   end
 
   it 'releases a successfully acquired lock when allocation fails and rolls back' do
-    allow(connection).to receive(:select_all).and_raise('query failed')
+    allow(connection).to receive(:select_value).with(/FOR UPDATE/).and_raise('query failed')
     expect { described_class.assign!(record) }.to raise_error(RuntimeError, 'query failed')
     callbacks.fetch(:after_rollback).call
     expect(sql.grep(/RELEASE_LOCK/).size).to eq(1)
   end
 
-  it 'accepts an explicit ID above the reserved position' do
+  it 'preserves explicitly supplied historical IDs' do
-    record.id = 50
+    record.id = 5
     described_class.assign!(record)
-    expect(record.id).to eq(50)
+    expect(record.id).to eq(5)
     expect(sql.grep(/FOR UPDATE/)).to be_empty
     callbacks.fetch(:after_commit).call
   end
 
   it 'uses the same named lock within each space and different locks between spaces' do
-    locks = [Tag, ExternalTag, TagDescription, TagGroup, TagDescriptionVersion, TagGroupVersion].map do |model|
+    locks = [Tag, ExternalTag, TagDescription, TagGroup].map do |model|
       allow(model).to receive(:connection).and_return(connection)
       allow(model).to receive(:current_transaction).and_return(transaction)
       allow(model).to receive(:uncached).and_yield
@@ -180,8 +76,7 @@ RSpec.describe SharedResourceIdAllocator, 'lock lifecycle' do
     end
     expect(locks[0]).to eq(locks[1])
     expect(locks[2]).to eq(locks[3])
-    expect(locks[4]).to eq(locks[5])
+    expect(locks[0]).not_to eq(locks[2])
-    expect([locks[0], locks[2], locks[4]].uniq.size).to eq(3)
   end
 
   it 'reports lock release failures' do

backend/spec/services/wiki/commit_integrity_spec.rb

@@ -0,0 +1,185 @@
+require 'digest'
+require 'rails_helper'
+
+RSpec.describe Wiki::Commit do
+  include WikiRecords
+  let(:user) { create_member_user! }
+
+  def create_page title:, body: 'initial body'
+    seed_wiki_page(
+        tag_name: create(:tag, primary_name: title).tag_name('ja'),
+        body:,
+        created_by_user: user,
+        message: 'init')
+  end
+
+  describe '.create_content!' do
+    it 'rejects standalone Help creation without adding page or history' do
+      name = create(:tag_name, name: 'Help:frozen_service')
+      counts = [WikiPage.count, WikiRevision.count, WikiVersion.count]
+      expect do
+        described_class.create_content!(tag_name: name, body: 'initial', created_by_user: user)
+      end.to raise_error(ActiveRecord::RecordInvalid)
+      expect([WikiPage.count, WikiRevision.count, WikiVersion.count]).to eq(counts)
+    end
+
+    it 'keeps the internal compatibility writer available' do
+      name = create(:tag_name, name: 'タググループ:compatibility_service')
+      page = nil
+      expect do
+        page = described_class.create_legacy_content!(
+            tag_name: name, body: 'initial', created_by_user: user)
+      end.to change(WikiPage, :count).by(1)
+          .and change(WikiRevision, :count).by(1)
+          .and change(WikiVersion, :count).by(1)
+      expect(page.current_revision.body).to eq('initial')
+      expect(page.wiki_versions.sole.body).to eq('initial')
+    end
+
+    it 'rejects body that becomes blank after normalisation' do
+      tag_name = create(:tag, primary_name: 'commit_integrity_blank').tag_name('ja')
+
+      expect {
+        described_class.create_content!(
+            tag_name:,
+            body: "\r\n\r\n",
+            created_by_user: user,
+            message: 'blank')
+      }
+          .to raise_error(ActiveRecord::RecordInvalid)
+
+      expect(WikiPage.where(tag_name:)).not_to exist
+    end
+  end
+
+  describe '.content!' do
+    it 'rejects standalone Help updates without modifying histories' do
+      page = seed_wiki_page(tag_name: create(:tag_name, name: 'Help:standalone'),
+                            body: 'before', created_by_user: user)
+      counts = [WikiRevision.count, WikiVersion.count]
+      expect do
+        described_class.content!(page:, body: 'after', created_user: user)
+      end.to raise_error(ActiveRecord::RecordInvalid)
+      expect(page.reload.body).to eq('before')
+      expect([WikiRevision.count, WikiVersion.count]).to eq(counts)
+    end
+
+    it 'updates page body, revision, and version' do
+      page = create_page(title: 'commit_integrity_update', body: 'before')
+      current_id = page.current_revision.id
+
+      expect {
+        described_class.content!(
+            page:,
+            body: 'after',
+            created_user: user,
+            message: 'edit',
+            base_revision_id: current_id)
+      }
+          .to change(WikiRevision, :count).by(1)
+          .and change(WikiVersion, :count).by(1)
+
+      page.reload
+      version = page.wiki_versions.order(:version_no).last
+
+      expect(page.body).to eq('after')
+      expect(version.body).to eq('after')
+      expect(version.reason).to eq('edit')
+    end
+
+    it 'does not record tag_version on body-only wiki update' do
+      tag_name = create(:tag_name, name: 'commit_integrity_linked_tag')
+      tag = create(:tag, primary_tag_name: tag_name, category: :general)
+
+      page =
+          seed_wiki_page(
+              tag_name:,
+              body: 'before',
+              created_by_user: user,
+              message: 'init')
+
+      TagVersionRecorder.record!(
+          tag:,
+          event_type: :create,
+          created_by_user: user)
+
+      before_count = tag.reload.tag_versions.count
+
+      described_class.content!(
+          page:,
+          body: 'after',
+          created_user: user,
+          message: 'edit',
+          base_revision_id: page.current_revision.id)
+
+      expect(tag.reload.tag_versions.count).to eq(before_count)
+    end
+
+    it 'raises conflict and leaves page, revision, and version unchanged' do
+      page = create_page(title: 'commit_integrity_conflict', body: 'first')
+      stale_id = page.current_revision.id
+
+      described_class.content!(
+          page:,
+          body: 'second',
+          created_user: user,
+          message: 'second',
+          base_revision_id: stale_id)
+
+      page.reload
+      before_body = page.body
+      before_revision_count = page.wiki_revisions.count
+      before_version_count = page.wiki_versions.count
+
+      expect {
+        described_class.content!(
+            page:,
+            body: 'third',
+            created_user: user,
+            message: 'stale',
+            base_revision_id: stale_id)
+      }
+          .to raise_error(Wiki::Commit::Conflict)
+
+      page.reload
+      expect(page.body).to eq(before_body)
+      expect(page.wiki_revisions.count).to eq(before_revision_count)
+      expect(page.wiki_versions.count).to eq(before_version_count)
+    end
+
+    it 'deduplicates duplicated missing wiki lines' do
+      page = create_page(title: 'commit_integrity_dedup', body: 'before')
+      duplicated = 'commit_integrity_duplicate_line'
+
+      described_class.content!(
+          page:,
+          body: "#{ duplicated }\n#{ duplicated }",
+          created_user: user,
+          message: 'dedup',
+          base_revision_id: page.current_revision.id)
+
+      revision = page.reload.current_revision
+
+      expect(WikiLine.where(body: duplicated).count).to eq(1)
+      expect(revision.wiki_revision_lines.count).to eq(2)
+      expect(revision.wiki_revision_lines.pluck(:wiki_line_id).uniq.size).to eq(1)
+    end
+  end
+
+  describe '.redirect!' do
+    it 'raises because redirect revisions are deprecated' do
+      page = create_page(title: 'commit_integrity_redirect_source', body: 'source')
+      target = create_page(title: 'commit_integrity_redirect_target', body: 'target')
+
+      expect {
+        described_class.redirect!(
+            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
+end

backend/spec/services/wiki/commit_spec.rb

@@ -0,0 +1,151 @@
+require 'rails_helper'
+
+RSpec.describe Wiki::Commit do
+  include WikiRecords
+  let(:user) { create_member_user! }
+
+  def create_page(title: 'commit_spec_page', body: 'initial body')
+    tag_name = create(:tag, primary_name: title).tag_name('ja')
+
+    seed_wiki_page(
+        tag_name:,
+        body:,
+        created_by_user: user,
+        message: 'init')
+  end
+
+  describe '.content!' do
+    it 'stores normalised body in wiki_pages and wiki_versions' do
+      page = create_page(title: 'commit_normalised_page')
+
+      described_class.content!(
+        page:,
+        body: "a\r\nb\r\n\r\n",
+        created_user: user,
+        message: 'init'
+      )
+
+      page.reload
+      version = page.wiki_versions.order(:version_no).last
+
+      expect(page.body).to eq("a\nb")
+      expect(version.body).to eq("a\nb")
+      expect(page.current_revision.lines_count).to eq(2)
+    end
+
+    it 'deduplicates duplicated missing wiki lines before upsert' do
+      page = create_page(title: 'commit_duplicate_line_page')
+      duplicated = 'commit_duplicate_line'
+
+      described_class.content!(
+        page:,
+        body: "#{ duplicated }\n#{ duplicated }",
+        created_user: user,
+        message: 'init'
+      )
+
+      page.reload
+
+      expect(WikiLine.where(body: duplicated).count).to eq(1)
+      expect(page.current_revision.lines_count).to eq(2)
+      expect(page.current_revision.wiki_revision_lines.count).to eq(2)
+    end
+
+    it 'raises conflict when base_revision_id is stale' do
+      page = create_page(title: 'commit_conflict_page')
+
+      first = described_class.content!(
+        page:,
+        body: 'first',
+        created_user: user,
+        message: 'first'
+      )
+
+      described_class.content!(
+        page:,
+        body: 'second',
+        created_user: user,
+        message: 'second',
+        base_revision_id: first.id
+      )
+
+      expect {
+        described_class.content!(
+          page:,
+          body: 'third',
+          created_user: user,
+          message: 'third',
+          base_revision_id: first.id
+        )
+      }.to raise_error(Wiki::Commit::Conflict)
+    end
+
+    it 'does not record tag version when corresponding tag has no versions' do
+      tag_name = create(:tag_name, name: 'commit_linked_tag_without_versions')
+      tag = create(:tag, primary_tag_name: tag_name, category: :general)
+
+      page =
+          seed_wiki_page(
+              tag_name:,
+              body: 'before',
+              created_by_user: user,
+              message: 'init')
+
+      expect(tag.reload.tag_versions.count).to eq(0)
+
+      current_revision_id = page.current_revision.id
+
+      expect {
+        described_class.content!(
+            page:,
+            body: 'after',
+            created_user: user,
+            message: 'edit',
+            base_revision_id: current_revision_id)
+      }.to change(WikiVersion, :count).by(1)
+
+      expect(tag.reload.tag_versions.count).to eq(0)
+    end
+
+    it 'does not record tag version when corresponding tag has no versions' do
+      tag_name = create(:tag_name, name: 'commit_linked_tag_without_versions')
+      tag = create(:tag, primary_tag_name: tag_name, category: :general)
+
+      page =
+          seed_wiki_page(
+              tag_name:,
+              body: 'before',
+              created_by_user: user,
+              message: 'init')
+
+      current_revision_id = page.current_revision.id
+
+      expect {
+        described_class.content!(
+            page:,
+            body: 'after',
+            created_user: user,
+            message: 'edit',
+            base_revision_id: current_revision_id)
+      }.to change(WikiVersion, :count).by(1)
+
+      expect(tag.reload.tag_versions.count).to eq(0)
+    end
+  end
+
+  describe '.redirect!' do
+    it 'raises because redirect revisions are deprecated' do
+      page = create_page(title: 'commit_redirect_source')
+      target = create_page(title: 'commit_redirect_target')
+
+      expect {
+        described_class.redirect!(
+          page:,
+          redirect_page: target,
+          created_user: user,
+          message: 'redirect'
+        )
+      }.to raise_error(RuntimeError, '廃止しました．')
+    end
+  end
+end

backend/spec/services/wiki_version_recorder_spec.rb

@@ -0,0 +1,100 @@
+require 'rails_helper'
+
+RSpec.describe WikiVersionRecorder do
+  include WikiRecords
+  let(:user) { create_member_user! }
+
+  def create_page title:, body: 'body'
+    seed_wiki_page(
+        tag_name: create(:tag_name, name: title),
+        body:,
+        created_by_user: user,
+        message: 'init')
+  end
+
+  describe '.record!' do
+    it 'records title, body, reason, user, and version number' do
+      page = create_page(title: 'wiki_version_recorder_basic', body: 'body')
+
+      expect {
+        described_class.record!(
+            page:,
+            event_type: :update,
+            reason: 'manual reason',
+            created_by_user: user)
+      }
+          .to change { page.reload.wiki_versions.count }.by(1)
+
+      version = page.wiki_versions.order(:version_no).last
+
+      expect(version).to have_attributes(
+        version_no: 2,
+        event_type: 'update',
+        title: 'wiki_version_recorder_basic',
+        body: 'body',
+        reason: 'manual reason',
+        created_by_user_id: user.id
+      )
+    end
+
+    it 'does not create duplicated update version for identical snapshot' do
+      page = create_page(title: 'wiki_version_recorder_duplicate', body: 'body')
+
+      described_class.record!(
+          page:,
+          event_type: :update,
+          reason: nil,
+          created_by_user: user)
+
+      before_count = page.reload.wiki_versions.count
+
+      described_class.record!(
+          page:,
+          event_type: :update,
+          reason: nil,
+          created_by_user: user)
+
+      expect(page.reload.wiki_versions.count).to eq(before_count)
+    end
+
+    it 'creates update version when title changes' do
+      page = create_page(title: 'wiki_version_recorder_title_before', body: 'body')
+      page.tag_name.update!(name: 'wiki_version_recorder_title_after')
+
+      expect {
+        described_class.record!(
+            page:,
+            event_type: :update,
+            reason: 'rename',
+            created_by_user: user)
+      }
+          .to change { page.reload.wiki_versions.count }.by(1)
+
+      version = page.wiki_versions.order(:version_no).last
+
+      expect(version.title).to eq('wiki_version_recorder_title_after')
+      expect(version.body).to eq('body')
+      expect(version.reason).to eq('rename')
+    end
+
+    it 'creates update version when body changes' do
+      page = create_page(title: 'wiki_version_recorder_body', body: 'before')
+      page.update!(body: 'after')
+
+      expect {
+        described_class.record!(
+            page:,
+            event_type: :update,
+            reason: 'body',
+            created_by_user: user)
+      }
+          .to change { page.reload.wiki_versions.count }.by(1)
+
+      version = page.wiki_versions.order(:version_no).last
+
+      expect(version.title).to eq('wiki_version_recorder_body')
+      expect(version.body).to eq('after')
+      expect(version.reason).to eq('body')
+    end
+  end
+end

backend/spec/support/ainu_locale_contract.rb

@@ -1,22 +0,0 @@
-RSpec.shared_context 'Ainu locale contract' do
-  let(:ainu_locale) { instance_double(Locale, language_code: 'ain', script_code: 'Jpan') }
-
-  before do
-    # Only the foreign-key reference is seeded; no Locale or enum is enabled.
-    Language.connection.execute(<<~SQL)
-      INSERT IGNORE INTO languages (code, name, created_at)
-      VALUES ('ain', 'Ainu', CURRENT_TIMESTAMP)
-    SQL
-    allow(Locale).to receive(:find_by).and_call_original
-    allow(Locale).to receive(:find_by).with(code: 'ain').and_return(ainu_locale)
-  end
-
-  def add_ainu_name tag, name
-    TagName.insert_all!([{
-        tag_id: tag.id, language_code: 'ain', script_code: 'Jpan', name:,
-        primary_flg: true, auto_generated: false,
-        created_at: Time.current, updated_at: Time.current }])
-    tag.tag_names.reset
-    TagName.find_by!(tag_id: tag.id, language_code: 'ain', name:)
-  end
-end

backend/spec/support/tag_group_records.rb

@@ -7,7 +7,8 @@ module TagGroupRecords
       'tag_groups', 'tag_group_tags', 'tag_group_groups',
       'tag_group_placements', 'tag_group_versions'].freeze
   WRITE_TABLES = GROUP_TABLES + [
-      'tag_names', 'tag_description_versions',
+      'wiki_pages', 'wiki_revisions', 'wiki_versions', 'wiki_lines',
+      'wiki_revision_lines', 'tag_names', 'tag_description_versions',
       'tag_descriptions']
 
   def group_connection = ApplicationRecord.connection
@@ -33,11 +34,13 @@ module TagGroupRecords
     WRITE_TABLES.to_h { |table| [table, group_rows(table)] }
   end
 
-  def expect_noop_group_update group_id:
+  def expect_noop_group_update group_id:, page:
     before_state = group_state
     group = TagGroup.find(group_id)
     version_id = TagGroupVersion.find_by!(
         tag_group_id: group_id, version_no: group.version_no).id
+    revision_id = page.reload.current_revision.id
+    wiki_version_id = page.wiki_versions.order(version_no: :desc).first.id
     writes = []
     tables = Regexp.union(WRITE_TABLES)
     subscriber = lambda do |*args|
@@ -56,6 +59,8 @@ module TagGroupRecords
       end
       expect(TagGroupVersion.find_by!(
           tag_group_id: group_id, version_no: group.reload.version_no).id).to eq(version_id)
+      expect(page.reload.current_revision.id).to eq(revision_id)
+      expect(page.wiki_versions.order(version_no: :desc).first.id).to eq(wiki_version_id)
       expect(writes).to be_empty
     end
   end
@@ -94,14 +99,25 @@ module TagGroupRecords
     tag.reload
   end
 
-  def create_markdown_group name, body, locale: Locale.nipponese
+  def legacy_group name, body
-    parsed = TagGroupMarkdownParser.parse(locale, body:)
+    # Historical fixtures preserve blank lines independently of today's writer.
-    TagGroupOperation.create!(
+    body = body.sub(/\n+\z/, '')
-        locale, name:, actor: user, **parsed.slice(:description, :members, :placements))
+    page = WikiPage.create!(
-  end
+        tag_name: create(:tag_name, name: "タググループ:#{ name }"),
-
+        body:, created_user: user, updated_user: user)
-  def group_markdown group, locale: Locale.nipponese
+    WikiVersionRecorder.record!(page:, event_type: :create, created_by_user: user)
-    TagGroupMarkdownRenderer.render(TagGroupRepr.one(locale, group.reload))
+    lines = body.split("\n")
+    shas = lines.map { Digest::SHA256.hexdigest(_1) }
+    revision = WikiRevision.create!(
+        wiki_page: page, kind: :content, created_user: user, lines_count: lines.size,
+        tree_sha256: Digest::SHA256.hexdigest(shas.join(',')))
+    lines.each_with_index do |line, position|
+      sha = shas.fetch(position)
+      line_id = WikiLine.find_by(sha256: sha)&.id || insert_group_row('wiki_lines', {
+          body: line, sha256: sha, created_at: Time.current, updated_at: Time.current })
+      WikiRevisionLine.create!(wiki_revision: revision, wiki_line_id: line_id, position:)
+    end
+    page
   end
 
   def seed_group name:, placements: [], members: [], description: nil, id: nil
@@ -160,6 +176,16 @@ module TagGroupRecords
     "/wiki/title/#{ CGI.escapeURIComponent("タググループ:#{ name }") }"
   end
 
+  def migrate_groups
+    require_relative '../../db/migrate/20261008010000_migrate_tag_groups_from_wiki_pages'
+    migration = MigrateTagGroupsFromWikiPages.new
+    @group_migration_messages = []
+    allow(migration).to receive(:say) do |message, *_args|
+      @group_migration_messages << message if message.start_with?('Wiki #', 'Tag Group')
+    end
+    migration.suppress_messages { migration.up }
+  end
+
   def expect_group_snapshot group_id, number:, placements:, members:, description: nil
     current = group_rows('tag_groups', id: group_id).sole
     version = group_version(group_id, number)

backend/spec/support/wiki_records.rb

@@ -1,14 +1,20 @@
+# Historical records must remain seedable after application creation is frozen.
 module WikiRecords
-  def seed_description(tag_name:, body:, created_by_user:, message: nil, locale: Locale.nipponese)
+  def seed_wiki_page(tag_name:, body:, created_by_user:, message: nil)
-    TagDescriptionOperation.create!(locale, tag: tag_name.tag, body:, created_by_user:, message:)
+    page = WikiPage.create!(tag_name:, body:,
-  end
+                            created_user: created_by_user, updated_user: created_by_user)
-
+    revision = Wiki::Commit.legacy_content!(
-  def description_versions(description)
+        page:, body:, created_user: created_by_user, message:)
-    TagDescriptionVersion.where(
+    if tag_name.tag && tag_name.language_code == 'ja'
-        tag_id: description.tag_id, language_code: description.language_code)
+      TagDescription.create!(
-  end
+          id: page.id, tag: tag_name.tag, language_code: 'ja', body: page.reload.body,
-
+          version_no: 1, created_by_user_id: created_by_user.id,
-  def current_description_version(description)
+          updated_by_user_id: created_by_user.id)
-    description_versions(description).find_by!(version_no: description.reload.version_no)
+      TagDescriptionVersion.create!(
+          id: revision.id, tag_id: tag_name.tag_id, language_code: 'ja',
+          version_no: 1, event_type: 'create', body: page.body,
+          created_by_user_id: created_by_user.id, created_at: revision.created_at)
+    end
+    page
   end
 end