#424

backend/spec/requests/tag_description_wiki_spec.rb

@@ -1,10 +1,11 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag description Wiki compatibility', type: :request do
+  include WikiRecords
   let!(:user) { create_member_user! }
   let!(:tag_name) { create(:tag_name, name: 'description_contract') }
   let!(:page) do
-    Wiki::Commit.create_content!(
+    seed_wiki_page(
         tag_name:, body: 'old-revision', created_by_user: user)
   end
   let!(:revisions) do
@@ -242,8 +243,8 @@ RSpec.describe 'Tag description Wiki compatibility', type: :request do
   end
 
   describe 'mixed changes' do
-    it 'includes unmigrated history and ignores migrated legacy-only revisions' do
+    it 'excludes unmigrated history and migrated legacy-only revisions' do
-      legacy_page = Wiki::Commit.create_content!(
+      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
@@ -256,7 +257,7 @@ RSpec.describe 'Tag description Wiki compatibility', type: :request do
       migrated = json.select { |row| row.fetch('wiki_page').fetch('id') == description.id }
       expect(migrated.map { |row| row.fetch('revision_id') }).to eq(versions.reverse.map(&:id))
       expect(json.map { |row| row.fetch('revision_id') }).not_to include(extra.id)
-      expect(json).to include(include(
+      expect(json).not_to include(include(
           'revision_id' => legacy_revision.id,
           'wiki_page' => include('id' => legacy_page.id, 'title' => 'Help_mixed')))
     end

backend/spec/requests/tag_description_wiki_write_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag description Wiki dual writes', type: :request do
+  include WikiRecords
   let!(:user) { create_member_user! }
   let!(:tag_name) { create(:tag_name, name: 'description_write') }
   let(:tag) { create(:tag, primary_tag_name: tag_name) }
@@ -31,25 +32,18 @@ RSpec.describe 'Tag description Wiki dual writes', type: :request do
            headers: headers
     end
 
-    it 'creates both current records and histories with a shared revision ID' do
+    it 'creates a description without implicitly creating Wiki records' do
       expect { create_description }
-          .to change(WikiPage, :count).by(1)
+          .to change(WikiPage, :count).by(0)
-          .and change(WikiRevision, :count).by(1)
+          .and change(WikiRevision, :count).by(0)
-          .and change(WikiVersion, :count).by(1)
+          .and change(WikiVersion, :count).by(0)
           .and change(TagDescription, :count).by(1)
           .and change(TagDescriptionVersion, :count).by(1)
       expect(response).to have_http_status(:created)
-
-      page = WikiPage.find(json.fetch('id'))
       description = TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
-      version = TagDescriptionVersion.find_by!(tag_id: tag.id, language_code: 'ja')
+      expect(description).to have_attributes(body: 'initial', version_no: 1)
-      expect(description).to have_attributes(id: page.id, body: 'initial', version_no: 1)
+      expect(TagDescriptionVersion.find_by!(tag_id: tag.id, language_code: 'ja'))
-      expect(version).to have_attributes(
+          .to have_attributes(body: 'initial', version_no: 1, created_by_user_id: user.id)
-          id: page.current_revision.id, body: 'initial', version_no: 1,
-          event_type: 'create', created_by_user_id: user.id)
-      expect(page.body).to eq(description.body)
-      expect(page.current_revision.body).to eq(version.body)
-      expect(page.wiki_versions.last.body).to eq(version.body)
     end
 
     ['missing_description', 'orphan_description'].each do |title|
@@ -65,48 +59,19 @@ RSpec.describe 'Tag description Wiki dual writes', type: :request do
       end
     end
 
-    it 'creates a namespaced legacy Wiki resource without a Tag' do
+    [false, true].each do |linked|
-      expect do
+      it "rejects namespaced creation with Tag present: #{ linked }" do
-        post '/wiki', params: { title: 'Help:description_write', body: 'legacy' },
+        name = create(:tag_name, name: 'Help:frozen')
-             headers: headers
+        create(:tag, primary_tag_name: name) if linked
-      end.to change(WikiPage, :count).by(1)
+        before_state = stored_state
-          .and change(WikiRevision, :count).by(1)
+        post '/wiki', params: { title: name.name, body: 'legacy' }, headers: headers
-          .and change(WikiVersion, :count).by(1)
+        expect(response.status).to be_between(400, 499)
-          .and change(TagDescription, :count).by(0)
+        expect(stored_state).to eq(before_state)
-          .and change(TagDescriptionVersion, :count).by(0)
+      end
-
-      expect(response).to have_http_status(:created)
-      page = WikiPage.find(json.fetch('id'))
-      expect(page.tag_name.tag).to be_nil
-      expect(page.body).to eq('legacy')
-      expect(page.current_revision.body).to eq('legacy')
     end
 
-    it 'creates only legacy Wiki for a namespaced title with an existing Tag' do
+    [TagDescription, TagDescriptionVersion].each do |model|
-      namespaced_name = create(:tag_name, name: 'help:foo')
+      it "rolls back new description creation when #{ model.name } persistence fails" do
-      namespaced_tag = create(:tag, primary_tag_name: namespaced_name)
-
-      expect do
-        post '/wiki', params: { title: namespaced_name.name, body: 'legacy' },
-             headers: headers
-      end.to change(WikiPage, :count).by(1)
-          .and change(WikiRevision, :count).by(1)
-          .and change(WikiVersion, :count).by(1)
-          .and change(TagName, :count).by(0)
-          .and change(TagDescription, :count).by(0)
-          .and change(TagDescriptionVersion, :count).by(0)
-
-      expect(response).to have_http_status(:created)
-      page = WikiPage.find(json.fetch('id'))
-      expect(page).to have_attributes(tag_name_id: namespaced_name.id, body: 'legacy')
-      expect(page.tag_name.tag).to eq(namespaced_tag)
-      expect(page.current_revision.body).to eq('legacy')
-      expect(page.wiki_versions.last.body).to eq('legacy')
-    end
-
-    [WikiPage, WikiRevision, WikiVersion, TagDescription, TagDescriptionVersion].each do |model|
-      it "rolls back both systems when #{ model.name } persistence fails" do
-        tag_name
         before_state = stored_state
         aggregate_failures do
           fail_save(model) { create_description }
@@ -119,7 +84,7 @@ RSpec.describe 'Tag description Wiki dual writes', type: :request do
   describe 'PUT /wiki/:id' do
     let!(:page) do
       tag
-      Wiki::Commit.create_content!(
+      seed_wiki_page(
           tag_name:, body: 'before', created_by_user: user)
     end
     let!(:first_revision) { page.current_revision }
@@ -138,7 +103,8 @@ RSpec.describe 'Tag description Wiki dual writes', type: :request do
       expect(page.reload.version_no).to eq(1)
       expect(description.version_no).to eq(1)
       expect { update_description }
-          .to change(WikiRevision, :count).by(1)
+          .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)
@@ -157,7 +123,8 @@ RSpec.describe 'Tag description Wiki dual writes', type: :request do
       tag_name.update_columns(tag_id: nil)
 
       expect { update_description }
-          .to change(WikiRevision, :count).by(1)
+          .to change(WikiPage, :count).by(0)
+          .and change(WikiRevision, :count).by(1)
           .and change(WikiVersion, :count).by(1)
           .and change(TagDescriptionVersion, :count).by(1)
 

backend/spec/requests/tag_group_wiki_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag group Wiki facade reads', type: :request do
+  include WikiRecords
   include TagGroupRecords
 
   let!(:user) { create_member_user! }
@@ -69,34 +70,36 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
     end
   end
 
-  it 'combines Tag Groups, Help and Tag Descriptions in the unfiltered list' do
+  it 'combines Tag Groups and Tag Descriptions without Help in the unfiltered list' do
-    help = Wiki::Commit.create_legacy_content!(
+    help = seed_wiki_page(
         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', help.title, '新タグ')
+        '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 'keeps Help readable when its ID collides with a new group' do
+  it 'excludes Help when its ID collides with a new group' do
-    help = Wiki::Commit.create_legacy_content!(
+    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(help.title, 'タググループ:別 ID重複')
+    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(:ok)
+    expect(response).to have_http_status(:not_found)
-    expect(json.fetch('body')).to eq('help body')
 
     get '/wiki/changes'
     expect(response).to have_http_status(:ok)
     expect(json.map { _1.dig('wiki_page', 'title') }).to include(
-        help.title, 'タググループ:別 ID重複')
+        '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
@@ -122,7 +125,7 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
   end
 
   it 'orders mixed resource history by timestamp rather than independent IDs' do
-    help = Wiki::Commit.create_legacy_content!(
+    help = seed_wiki_page(
         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)
@@ -136,8 +139,8 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
     timestamps = json.map { Time.iso8601(_1.fetch('timestamp')) }
     expect(timestamps).to eq(timestamps.sort.reverse)
     titles = json.map { _1.dig('wiki_page', 'title') }
-    expect(titles.index('新タグ')).to be < titles.index(help.title)
+    expect(titles).not_to include(help.title)
-    expect(titles.index(help.title)).to be < titles.index('タググループ:読取り契約')
+    expect(titles.index('新タグ')).to be < titles.index('タググループ:読取り契約')
   end
 
   it 'renders nullable group editors without raising' do
@@ -166,16 +169,16 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
         'wiki_page' => include('id' => page.id, 'title' => 'タググループ:読取り契約'))
   end
 
-  it 'includes Help and group history but excludes legacy-only migrated revisions' do
+  it 'includes group history but excludes all legacy-only revisions' do
     extra = Wiki::Commit.legacy_content!(page:, body: 'legacy only', created_user: user)
-    help = Wiki::Commit.create_legacy_content!(
+    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).to include(include(
+    expect(json).not_to include(include(
         'revision_id' => help.current_revision.id,
         'wiki_page' => include('title' => help.title)))
   end
@@ -214,7 +217,7 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
 
   context 'when Help, description and group share the same numeric ID' do
     let(:colliding_help) do
-      Wiki::Commit.create_legacy_content!(
+      seed_wiki_page(
           tag_name: create(:tag_name, name: 'Help:三者ID衝突'),
           body: 'help', created_by_user: user)
     end
@@ -239,13 +242,12 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
       colliding_description_version
     end
 
-    it 'lists all three resources without deduplicating their numeric ID' do
+    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_help.id, colliding_help.title],
           [colliding_description.id, '新タグ'],
           [colliding_group_id, 'タググループ:三者ID衝突'])
     end
@@ -259,7 +261,6 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
         [row.fetch('revision_id'), row.fetch('wiki_page').fetch('title')]
       end
       expect(histories).to contain_exactly(
-          [colliding_help.current_revision.id, colliding_help.title],
           [colliding_description_version.id, '新タグ'],
           [group_version(colliding_group_id, 1).fetch('id'), 'タググループ:三者ID衝突'])
     end
@@ -285,8 +286,8 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
     end
   end
 
-  it 'resolves colliding group, Help and description IDs by title' do
+  it 'resolves new resources by title while excluding colliding legacy Help' do
-    help = Wiki::Commit.create_legacy_content!(
+    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!(
@@ -294,11 +295,15 @@ RSpec.describe 'Tag group Wiki facade reads', type: :request do
     TagDescriptionVersion.create!(
         tag_id: new_tag.id, language_code: 'ja', version_no: 1,
         event_type: 'create', body: 'description', created_at: Time.current)
-    { 'タググループ:ID衝突' => 'group', 'Help:ID衝突' => 'help', '新タグ' => 'description' }
+    { '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

@@ -33,8 +33,11 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
     end
   end
 
-  it 'creates the group, first snapshot and compatibility Wiki history' do
+  it 'creates the group and first snapshot without new Wiki records' do
-    create_group
+    expect { create_group }
+        .to change(WikiPage, :count).by(0)
+        .and change(WikiRevision, :count).by(0)
+        .and change(WikiVersion, :count).by(0)
     expect(response).to have_http_status(:created)
     group = group_rows('tag_groups', name: '新規').sole
     expect(json).to include('id' => group.fetch('id'), 'title' => 'タググループ:新規')
@@ -42,11 +45,6 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
     version = group_version(group.fetch('id'), 1)
     expect(version).to include('event_type' => 'create', 'created_by_user_id' => user.id)
     expect(group).to include('created_by_user_id' => user.id, 'updated_by_user_id' => user.id)
-    page = WikiPage.joins(:tag_name).find_by!(tag_names: { name: 'タググループ:新規' })
-    expect(page.body.strip).to eq('- 洗澡鹿')
-    expect(page.current_revision.body).to eq(page.body)
-    expect(page.wiki_versions.sole.body).to eq(page.body)
-    # New IDs are independently allocated; no global identity assertion here.
   end
 
   it 'keeps repeated placements but only one membership and one snapshot member' do
@@ -293,8 +291,9 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
         expect(group_state).to eq(before_state)
       end
 
-      (TagGroupRecords::GROUP_TABLES + ['wiki_pages', 'wiki_revisions', 'wiki_versions'])
+      tables = TagGroupRecords::GROUP_TABLES
-          .each do |table|
+      tables += ['wiki_pages', 'wiki_revisions', 'wiki_versions'] if operation == :update
+      tables.each do |table|
         it "rolls back all writes after a real #{ table } write fails" do
           expect_atomic_group_write(table) { write_group(operation, headers) }
         end

backend/spec/requests/tag_group_write_integrity_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag group write integrity', type: :request do
+  include WikiRecords
   include TagGroupRecords
   include ActiveSupport::Testing::TimeHelpers
 
@@ -24,7 +25,7 @@ RSpec.describe 'Tag group write integrity', type: :request do
   end
 
   def create_help body
-    Wiki::Commit.create_legacy_content!(
+    seed_wiki_page(
         tag_name: create(:tag_name, name: 'Help:既存'), body:, created_by_user: user)
   end
 
@@ -136,14 +137,14 @@ RSpec.describe 'Tag group write integrity', type: :request do
       id = seed_group(name: '更新', id: help.id, members:, placements:)
       help_before = help.attributes
 
-      put "/tag_groups/#{ id }", params: native_payload(name: '改名'), headers:, as: :json
+      expect do
+        put "/tag_groups/#{ id }", params: native_payload(name: '改名'), headers:, as: :json
+      end.to change(WikiPage, :count).by(0)
+          .and change(WikiRevision, :count).by(0)
+          .and change(WikiVersion, :count).by(0)
 
       expect(response).to have_http_status(:ok)
-      page = WikiPage.joins(:tag_name).find_by!(tag_names: { name: 'タググループ:改名' })
+      expect(TagGroup.find(id).name).to eq('改名')
-      expect(page.id).not_to eq(help.id)
-      expect(page.body).to eq('- 洗澡鹿')
-      expect(page.current_revision.body).to eq(page.body)
-      expect(page.wiki_versions.sole.body).to eq(page.body)
       expect(help.reload.attributes).to eq(help_before)
     end
 

backend/spec/requests/tag_groups_spec.rb

@@ -391,7 +391,18 @@ RSpec.describe 'Tag group native API', type: :request do
         end
       end
 
-      [:create, :update].each do |operation|
+      it 'creates native state without adding compatibility Wiki records' do
+        expect { native_write(:create) }
+            .to change(WikiPage, :count).by(0)
+            .and change(WikiRevision, :count).by(0)
+            .and change(WikiVersion, :count).by(0)
+        expect(response).to have_http_status(:created)
+        expect_group_snapshot(
+            json.fetch('id'), number: 1, members: snapshot_members,
+            placements:, description: '全体の説明')
+      end
+
+      [:update].each do |operation|
         it "synchronises Wiki current state and histories on native #{ operation }" do
           native_write(operation)
           expect(response).to have_http_status(operation == :create ? :created : :ok)
@@ -418,19 +429,18 @@ RSpec.describe 'Tag group native API', type: :request do
         end
       end
 
-      it 'uses AUTO_INCREMENT for a new group instead of supplying a compatibility ID' do
+      it 'assigns the next group ID from the existing maximum' do
-        inserts = []
+        child_id
-        subscriber = lambda do |*args|
+        expected_id = (TagGroup.maximum(:id) || 0) + 1
-          sql = args.last.fetch(:sql)
+        native_write(:create)
-          inserts << sql if sql.match?(/\A\s*INSERT INTO `?tag_groups`?\s/i)
-        end
-        ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') do
-          native_write(:create)
-        end
         expect(response).to have_http_status(:created)
-        expect(inserts.size).to eq(1)
+        expect(json.fetch('id')).to eq(expected_id)
-        columns = inserts.sole[/\((.*?)\)/, 1].split(',').map { _1.strip.delete('`') }
+      end
-        expect(columns).not_to include('id')
+
+      TagGroupRecords::GROUP_TABLES.each do |table|
+        it "rolls back native creation after #{ table } writes" do
+          expect_atomic_group_write(table) { native_write(:create) }
+        end
       end
 
       it 'updates a native group through Wiki and then reads structured current data' do

backend/spec/requests/tag_resource_ids_spec.rb

@@ -0,0 +1,91 @@
+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 seed_description id
+    tag = create(:tag, primary_name: "description_id_#{ id }")
+    TagDescription.create!(id:, tag:, language_code: 'ja', body: 'existing', version_no: 1)
+  end
+
+  def create_resource resource
+    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)
+  end
+
+  [:description, :group].each do |resource|
+    it "ignores the other resource's larger maximum when allocating #{ resource }" do
+      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(2)
+    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 } from its own maximum, preserving gaps and existing rows" 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)
+
+      expected_id = resource == :description ? 6 : 9
+      expect(json.fetch('id')).to eq(expected_id)
+      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 'preserves group ID and unrelated rows on update' do
+    id = seed_group(name: 'existing', id: 5, description: 'before')
+    other_id = seed_group(name: 'other', id: 8, description: 'other')
+    other = TagGroup.find(other_id).attributes
+    put "/tag_groups/#{ id }", params: {
+        name: 'renamed', description: 'after', members: [], placements: [] }, headers:, as: :json
+    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 description identity on a compatibility update' do
+    tag = create(:tag, primary_name: 'existing_description')
+    page = seed_wiki_page(tag_name: tag.tag_name('ja'), body: 'before', created_by_user: user)
+    description = TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
+    id = description.id
+    put "/wiki/#{ id }", params: {
+        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(id)
+    expect(description.body).to eq('after')
+    expect(TagDescription.count).to eq(1)
+  end
+end

backend/spec/requests/tag_wiki_history_integrity_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Tag and wiki history integrity', type: :request do
+  include WikiRecords
   let(:member_user) { create(:user, role: 'member') }
 
   def stub_current_user user
@@ -13,7 +14,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
   end
 
   def create_wiki_for_tag! tag:, body: 'wiki body', user: member_user
-    Wiki::Commit.create_content!(
+    seed_wiki_page(
         tag_name: primary_tag_name_for(tag, 'ja'),
         body:,
         created_by_user: user,

backend/spec/requests/wiki_conflict_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Wiki conflict handling', type: :request do
+  include WikiRecords
   let!(:user) { create_member_user! }
 
   def auth_headers user
@@ -9,7 +10,7 @@ RSpec.describe 'Wiki conflict handling', type: :request do
 
   it 'returns 409 when base_revision_id is stale' do
     page =
-        Wiki::Commit.create_content!(
+        seed_wiki_page(
             tag_name: create(:tag_name, name: 'wiki_conflict_request'),
             body: 'first',
             created_by_user: user,

backend/spec/requests/wiki_creation_freeze_spec.rb

@@ -0,0 +1,59 @@
+require 'rails_helper'
+
+RSpec.describe 'Wiki creation freeze', type: :request do
+  include TagGroupRecords
+  include WikiRecords
+
+  let!(:user) { create_member_user! }
+  let(:headers) { { 'X-Transfer-Code' => user.inheritance_code } }
+
+  it 'updates an independent group without implicitly creating a legacy page' 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(0)
+        .and change(WikiRevision, :count).by(0)
+        .and change(WikiVersion, :count).by(0)
+    expect(response).to have_http_status(:ok)
+    expect(TagGroup.find(id).description).to eq('after')
+  end
+
+  context 'existing description write protection' do
+    let!(:tag) { create(:tag, primary_name: 'protected_description') }
+    let!(:page) do
+      seed_wiki_page(tag_name: tag.tag_name('ja'), body: 'before', created_by_user: user)
+    end
+
+    [nil, :guest, :banned].each do |role|
+      it "rejects #{ role || 'anonymous' } without changing either history" do
+        actor = role && create(:user, role == :banned ? :member : role)
+        actor.update!(banned_at: Time.current) if role == :banned
+        request_headers = actor ? { 'X-Transfer-Code' => actor.inheritance_code } : { }
+        before_state = group_state
+        put "/wiki/#{ page.id }", params: { title: tag.name('ja'), body: 'after' },
+            headers: request_headers
+        expect(response).to have_http_status(role ? :forbidden : :unauthorized)
+        expect(group_state).to eq(before_state)
+      end
+    end
+
+    it 'rejects banned IPs without writes' do
+      IpAddress.create!(ip_address: IPAddr.new('127.0.0.1').hton, banned_at: Time.current)
+      before_state = group_state
+      put "/wiki/#{ page.id }", params: { title: tag.name('ja'), body: 'after' }, headers: headers
+      expect(response).to have_http_status(:forbidden)
+      expect(group_state).to eq(before_state)
+    end
+
+    ['', "\r\n\r\n"].each do |body|
+      it "rejects invalid description body #{ body.inspect } atomically" do
+        before_state = group_state
+        put "/wiki/#{ page.id }", params: { title: tag.name('ja'), body: }, headers: headers
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(group_state).to eq(before_state)
+      end
+    end
+  end
+end

backend/spec/requests/wiki_history_integrity_spec.rb

@@ -2,6 +2,7 @@ require 'cgi'
 require 'rails_helper'
 
 RSpec.describe 'Wiki history integrity', type: :request do
+  include WikiRecords
   let!(:user) { create_member_user! }
 
   def auth_headers user
@@ -9,7 +10,7 @@ RSpec.describe 'Wiki history integrity', type: :request do
   end
 
   def create_wiki_page title:, body: 'body', message: 'init', user: self.user
-    Wiki::Commit.create_content!(
+    seed_wiki_page(
         tag_name: create(:tag_name, name: title),
         body:,
         created_by_user: user,
@@ -17,41 +18,14 @@ RSpec.describe 'Wiki history integrity', type: :request do
   end
 
   describe 'POST /wiki' do
-    it 'creates wiki_page, wiki_revision, and wiki_version atomically' do
+    it 'rejects frozen creation without partial page or history' do
-      expect {
+      expect do
-        post '/wiki',
+        post '/wiki', params: { title: 'Help:wiki_history_create_atomic', body: 'initial' },
-             params: {
-               title: 'Help:wiki_history_create_atomic',
-               body: "a\nb\nc",
-               message: 'initial commit',
-             },
              headers: auth_headers(user)
-      }
+      end.to change(WikiPage, :count).by(0)
-          .to change(WikiPage, :count).by(1)
+          .and change(WikiRevision, :count).by(0)
-          .and change(WikiRevision, :count).by(1)
+          .and change(WikiVersion, :count).by(0)
-          .and change(WikiVersion, :count).by(1)
+      expect(response.status).to be_between(400, 499)
-
-      expect(response).to have_http_status(:created)
-
-      page = WikiPage.find(json.fetch('id'))
-      revision = page.current_revision
-      version = page.wiki_versions.order(:version_no).last
-
-      expect(page.title).to eq('Help:wiki_history_create_atomic')
-      expect(page.body).to eq("a\nb\nc")
-
-      expect(revision).to be_content
-      expect(revision.message).to eq('initial commit')
-      expect(revision.lines_count).to eq(3)
-
-      expect(version).to have_attributes(
-        version_no: 1,
-        event_type: 'create',
-        title: 'Help:wiki_history_create_atomic',
-        body: "a\nb\nc",
-        reason: 'initial commit',
-        created_by_user_id: user.id
-      )
     end
 
     it 'returns 422 and creates nothing when normalised body is blank' do
@@ -71,21 +45,19 @@ RSpec.describe 'Wiki history integrity', type: :request do
           .where(tag_names: { name: 'Help:wiki_history_blank_body' })).not_to exist
     end
 
-    it 'returns 422 and creates no partial page when title already exists' do
+    it 'rejects frozen creation without modifying an existing page or history' do
       create_wiki_page(title: 'Help:wiki_history_duplicate_title', body: 'first')
 
-      expect {
+      expect do
         post '/wiki',
-             params: {
+             params: { title: 'Help:wiki_history_duplicate_title',
-               title: 'Help:wiki_history_duplicate_title',
+                       body: 'second', message: 'duplicate' },
-               body: 'second',
-               message: 'duplicate',
-             },
              headers: auth_headers(user)
-      }
+      end.to change(WikiPage, :count).by(0)
-          .not_to change(WikiPage, :count)
+          .and change(WikiRevision, :count).by(0)
+          .and change(WikiVersion, :count).by(0)
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      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

backend/spec/requests/wiki_spec.rb

@@ -4,6 +4,7 @@ require 'securerandom'
 
 
 RSpec.describe 'Wiki API', type: :request do
+  include WikiRecords
   def auth_headers(user)
     { 'X-Transfer-Code' => user.inheritance_code }
   end
@@ -18,7 +19,7 @@ RSpec.describe 'Wiki API', type: :request do
         deprecated_at: Time.zone.local(2026, 6, 1))
   end
   let!(:page) do
-    Wiki::Commit.create_content!(
+    seed_wiki_page(
         tag_name: tn,
         body: 'init',
         created_by_user: user,
@@ -108,94 +109,14 @@ RSpec.describe 'Wiki API', type: :request do
       end
     end
 
-    context 'when success' do
+    ['Help:TestPage', 'ヘルプ:ホーム'].each do |title|
-      it 'creates wiki_page and first content revision' do
+      it "rejects frozen creation of #{ title } without history writes" do
         expect do
-          post endpoint, params: { title: 'Help:TestPage', body: "a\nb\nc", message: 'init' },
+          post endpoint, params: { title:, body: 'initial' }, headers: auth_headers(member)
-                         headers: auth_headers(member)
+        end.to change(WikiPage, :count).by(0)
-        end
+            .and change(WikiRevision, :count).by(0)
-            .to change(WikiPage, :count).by(1)
+            .and change(WikiVersion, :count).by(0)
-            .and change(WikiRevision, :count).by(1)
+        expect(response.status).to be_between(400, 499)
-            .and change(WikiVersion, :count).by(1)
-
-        expect(response).to have_http_status(:created)
-
-        page_id = json.fetch('id')
-        expect(json.fetch('title')).to eq('Help:TestPage')
-
-        created_page = WikiPage.find(page_id)
-        version = created_page.wiki_versions.order(:version_no).last
-
-        expect(version).to have_attributes(
-          version_no: 1,
-          event_type: 'create',
-          title: 'Help:TestPage',
-          body: "a\nb\nc",
-          created_by_user_id: member.id
-        )
-
-        rev = created_page.current_revision
-        expect(rev).to be_present
-        expect(rev).to be_content
-        expect(rev.message).to eq('init')
-
-        expect(created_page.body).to eq("a\nb\nc")
-
-        expect(rev.lines_count).to eq(3)
-        expect(rev.wiki_revision_lines.order(:position).pluck(:position)).to eq([0, 1, 2])
-        expect(rev.wiki_lines.pluck(:body)).to match_array(['a', 'b', 'c'])
-      end
-
-      it 'reuses existing WikiLine rows by sha256' do
-        # 先に同じ行を作っておく
-        WikiLine.create!(sha256: Digest::SHA256.hexdigest('a'), body: 'a', created_at: Time.current, updated_at: Time.current)
-
-        post endpoint,
-             params: { title: 'Help:Reuse', body: "a\na" },
-             headers: auth_headers(member)
-
-        page = WikiPage.find(JSON.parse(response.body).fetch('id'))
-        rev = page.current_revision
-        expect(rev.lines_count).to eq(2)
-
-        # "a" の WikiLine が増殖しない（1行のはず）
-        expect(WikiLine.where(body: 'a').count).to eq(1)
-      end
-
-      it 'deduplicates duplicated new lines before upsert' do
-        duplicated = 'duplicated_line_for_wiki_line_upsert_spec'
-
-        post endpoint,
-             params: { title: 'Help:DuplicateNewLine', body: "#{ duplicated }\n#{ duplicated }" },
-             headers: auth_headers(member)
-
-        expect(response).to have_http_status(:created)
-
-        page = WikiPage.find(json.fetch('id'))
-        rev = page.current_revision
-
-        expect(rev.lines_count).to eq(2)
-        expect(WikiLine.where(body: duplicated).count).to eq(1)
-        expect(rev.wiki_revision_lines.count).to eq(2)
-        expect(rev.wiki_revision_lines.pluck(:wiki_line_id).uniq.size).to eq(1)
-      end
-
-      it 'normalises CRLF and strips trailing newlines' do
-        post endpoint,
-             params: { title: 'Help:NormalisedBody',
-                       body: "a\r\nb\r\n\r\n", message: 'normalise' },
-             headers: auth_headers(member)
-
-        expect(response).to have_http_status(:created)
-
-        page = WikiPage.find(json.fetch('id'))
-        rev = page.current_revision
-        version = page.wiki_versions.order(:version_no).last
-
-        expect(page.body).to eq("a\nb")
-        expect(version.body).to eq("a\nb")
-        expect(rev.lines_count).to eq(2)
-        expect(rev.wiki_lines.order('wiki_revision_lines.position').map(&:body)).to eq(['a', 'b'])
       end
     end
   end
@@ -211,7 +132,7 @@ RSpec.describe 'Wiki API', type: :request do
     let!(:test_tag_name) { create(:tag_name, name: 'TestPage') }
 
     let!(:page) do
-      Wiki::Commit.create_content!(
+      seed_wiki_page(
           tag_name: test_tag_name,
           body: "a\nb",
           created_by_user: member,
@@ -249,7 +170,8 @@ RSpec.describe 'Wiki API', type: :request do
 
         expect do
           put "/wiki/#{page.id}",
-              params: { title: 'TestPage', body: "x\ny", message: 'edit', base_revision_id: current_id },
+              params: { title: 'TestPage', body: "x\ny", message: 'edit',
+                        base_revision_id: current_id },
               headers: auth_headers(member)
         end
             .to change(WikiRevision, :count).by(1)
@@ -284,7 +206,7 @@ RSpec.describe 'Wiki API', type: :request do
             created_by_user: member)
 
         linked_page =
-            Wiki::Commit.create_content!(
+            seed_wiki_page(
                 tag_name: linked_tag_name,
                 body: 'before',
                 created_by_user: member,
@@ -358,13 +280,14 @@ RSpec.describe 'Wiki API', type: :request do
 
   describe 'GET /wiki/search' do
     before do
-      Wiki::Commit.create_content!(
+      search_tag = create(:tag, primary_name: 'spec_wiki_title_2')
-          tag_name: create(:tag_name, name: 'spec_wiki_title_2'),
+      seed_wiki_page(
+          tag_name: search_tag.tag_name('ja'),
           body: 'search body 2',
           created_by_user: user,
           message: 'init')
 
-      Wiki::Commit.create_content!(
+      seed_wiki_page(
           tag_name: create(:tag_name, name: 'unrelated_title'),
           body: 'unrelated body',
           created_by_user: user,
@@ -516,7 +439,7 @@ RSpec.describe 'Wiki API', type: :request do
     it 'raises because redirect revisions are deprecated' do
       target_tag_name = create(:tag_name, name: 'redirect_deprecated_target')
       target =
-          Wiki::Commit.create_content!(
+          seed_wiki_page(
               tag_name: target_tag_name,
               body: 'target',
               created_by_user: user,
@@ -539,7 +462,7 @@ RSpec.describe 'Wiki API', type: :request do
     linked_tag = create(:tag, primary_tag_name: linked_tag_name, category: :general)
 
     linked_page =
-        Wiki::Commit.create_content!(
+        seed_wiki_page(
             tag_name: linked_tag_name,
             body: 'before',
             created_by_user: user,

backend/spec/requests/wiki_title_collision_spec.rb

@@ -1,6 +1,7 @@
 require 'rails_helper'
 
 RSpec.describe 'Wiki title collision', type: :request do
+  include WikiRecords
   let!(:user) { create_member_user! }
 
   def auth_headers user
@@ -8,7 +9,7 @@ RSpec.describe 'Wiki title collision', type: :request do
   end
 
   def create_wiki_page title:, body:
-    Wiki::Commit.create_content!(
+    seed_wiki_page(
         tag_name: create(:tag_name, name: title),
         body:,
         created_by_user: user,
@@ -43,20 +44,18 @@ RSpec.describe 'Wiki title collision', type: :request do
     expect(source.wiki_versions.count).to eq(source_version_count)
   end
 
-  it 'returns 422 when creating wiki with existing title' do
+  it 'rejects frozen creation with an existing title without adding history' do
     create_wiki_page(title: 'Help:wiki_collision_create', body: 'already exists')
 
-    expect {
+    expect do
       post '/wiki',
-           params: {
+           params: { title: 'Help:wiki_collision_create', body: 'new body',
-             title: 'Help:wiki_collision_create',
+                     message: 'duplicate create' },
-             body: 'new body',
-             message: 'duplicate create',
-           },
            headers: auth_headers(user)
-    }
+    end.to change(WikiPage, :count).by(0)
-        .not_to change(WikiPage, :count)
+        .and change(WikiRevision, :count).by(0)
+        .and change(WikiVersion, :count).by(0)
 
-    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response.status).to be_between(400, 499)
   end
 end

backend/spec/requests/wiki_unmigrated_contract_spec.rb

@@ -1,10 +1,11 @@
 require 'rails_helper'
 
 RSpec.describe 'Unmigrated Wiki compatibility', type: :request do
+  include WikiRecords
   let!(:user) { create_member_user! }
   let!(:tag_name) { create(:tag_name, name: 'Help_contract') }
   let!(:page) do
-    Wiki::Commit.create_content!(tag_name:, body: 'before', created_by_user: user)
+    seed_wiki_page(tag_name:, body: 'before', created_by_user: user)
   end
   let!(:first_revision) { page.current_revision }
   let!(:last_revision) do
@@ -33,83 +34,45 @@ RSpec.describe 'Unmigrated Wiki compatibility', type: :request do
     expect(page.current_revision).to have_attributes(message: 'legacy rename')
   end
 
-  it 'shows legacy current and historical content by ID' do
+  include TagGroupRecords
-    get "/wiki/#{ page.id }"
+
-    expect(response).to have_http_status(:ok)
+  [:id, :title].each do |lookup|
-    expect(json).to include('body' => 'after', 'revision_id' => last_revision.id,
+    [nil, :historical].each do |edition|
-                           'pred' => first_revision.id, 'succ' => nil)
+      it "rejects legacy #{ lookup } #{ edition || 'current' } without legacy SELECTs" do
-    get "/wiki/#{ page.id }", params: { version: first_revision.id }
+        path = lookup == :id ? "/wiki/#{ page.id }" : "/wiki/title/#{ tag_name.name }"
-    expect(response).to have_http_status(:ok)
+        params = edition ? { version: first_revision.id } : { }
-    expect(json).to include('body' => 'before', 'revision_id' => first_revision.id,
+        without_group_legacy_reads { get path, params: }
-                           'pred' => nil, 'succ' => last_revision.id)
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+
+    it "does not recognise legacy #{ lookup } existence" do
+      path = lookup == :id ? "/wiki/#{ page.id }" : "/wiki/title/#{ tag_name.name }"
+      without_group_legacy_reads { get "#{ path }/exists" }
+      expect(response).to have_http_status(:not_found)
+    end
   end
 
-  it 'shows legacy current and historical content by title' do
+  ['/wiki', '/wiki/search', '/wiki/changes'].each do |path|
-    get "/wiki/title/#{ tag_name.name }"
+    it "excludes unmigrated content from #{ path } without legacy SELECTs" do
-    expect(response).to have_http_status(:ok)
+      without_group_legacy_reads { get path }
-    expect(json).to include('body' => 'after', 'revision_id' => last_revision.id)
-    get "/wiki/title/#{ tag_name.name }", params: { version: first_revision.id }
-    expect(response).to have_http_status(:ok)
-    expect(json).to include('body' => 'before', 'revision_id' => first_revision.id)
-  end
-
-  it 'recognises legacy IDs' do
-    get "/wiki/#{ page.id }/exists"
-    expect(response).to have_http_status(:no_content)
-  end
-
-  it 'recognises legacy titles' do
-    get "/wiki/title/#{ tag_name.name }/exists"
-    expect(response).to have_http_status(:no_content)
-  end
-
-  it 'diffs legacy revisions with explicit and current target' do
-    [last_revision.id, nil].each do |to|
-      get "/wiki/#{ page.id }/diff", params: { from: first_revision.id, to: }
       expect(response).to have_http_status(:ok)
-      expect(json).to include(
+      expect(json).to eq([])
-          'wiki_page_id' => page.id, 'title' => tag_name.name,
-          'older_revision_id' => first_revision.id, 'newer_revision_id' => last_revision.id,
-          'diff' => [{ 'type' => 'removed', 'content' => 'before' },
-                     { 'type' => 'added', 'content' => 'after' }])
     end
   end
 
-  describe 'revision resource scope' do
+  it 'returns empty scoped history without legacy SELECTs' do
-    let!(:other_page) do
+    without_group_legacy_reads { get '/wiki/changes', params: { id: page.id } }
-      Wiki::Commit.create_content!(
-          tag_name: create(:tag_name, name: 'Help_other_contract'),
-          body: 'other page history', created_by_user: user)
-    end
-    let(:other_revision) { other_page.current_revision }
-
-    it 'returns 404 when show specifies another page revision' do
-      get "/wiki/#{ page.id }", params: { version: other_revision.id }
-      expect(response).to have_http_status(:not_found)
-    end
-
-    it 'returns 404 when diff from belongs to another page' do
-      get "/wiki/#{ page.id }/diff",
-          params: { from: other_revision.id, to: last_revision.id }
-      expect(response).to have_http_status(:not_found)
-    end
-
-    it 'returns 404 when diff to belongs to another page' do
-      get "/wiki/#{ page.id }/diff",
-          params: { from: first_revision.id, to: other_revision.id }
-      expect(response).to have_http_status(:not_found)
-    end
-  end
-
-  it 'retains legacy history metadata and ordering' do
-    get '/wiki/changes', params: { id: page.id }
     expect(response).to have_http_status(:ok)
-    expect(json.map { |row| row.fetch('revision_id') }).to eq(
+    expect(json).to eq([])
-        [last_revision.id, first_revision.id])
+  end
-    expect(json.first).to include(
+
-        'pred' => first_revision.id, 'succ' => nil, 'kind' => 'content',
+  [false, true].each do |explicit|
-        'message' => 'legacy edit', 'timestamp' => last_revision.created_at.iso8601(3),
+    it "rejects legacy diff with #{ explicit ? 'explicit' : 'current' } target" do
-        'wiki_page' => { 'id' => page.id, 'title' => tag_name.name, 'deprecated_at' => nil },
+      params = { from: first_revision.id }
-        'user' => { 'id' => user.id, 'name' => user.name })
+      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/wiki/commit_integrity_spec.rb

@@ -2,10 +2,11 @@ require 'digest'
 require 'rails_helper'
 
 RSpec.describe Wiki::Commit do
+  include WikiRecords
   let(:user) { create_member_user! }
 
   def create_page title:, body: 'initial body'
-    described_class.create_content!(
+    seed_wiki_page(
         tag_name: create(:tag_name, name: title),
         body:,
         created_by_user: user,
@@ -13,26 +14,18 @@ RSpec.describe Wiki::Commit do
   end
 
   describe '.create_content!' do
-    it 'creates page, revision, and version with normalised body' do
+    [:create_content!, :create_legacy_content!].each do |operation|
-      expect {
+      it "freezes #{ operation } without adding page or history" do
-        described_class.create_content!(
+        name = create(:tag_name, name: 'Help:frozen_service')
-            tag_name: create(:tag_name, name: 'commit_integrity_create'),
+        counts = [WikiPage.count, WikiRevision.count, WikiVersion.count]
-            body: "a\r\nb\r\n\r\n",
+        begin
-            created_by_user: user,
+          described_class.public_send(operation, tag_name: name, body: 'initial',
-            message: 'init')
+                                      created_by_user: user)
-      }
+        rescue ActiveRecord::RecordInvalid
-          .to change(WikiPage, :count).by(1)
+          # A validation rejection is allowed; persistence is not.
-          .and change(WikiRevision, :count).by(1)
+        end
-          .and change(WikiVersion, :count).by(1)
+        expect([WikiPage.count, WikiRevision.count, WikiVersion.count]).to eq(counts)
-
+      end
-      page = WikiPage.joins(:tag_name).find_by!(tag_names: { name: 'commit_integrity_create' })
-      revision = page.current_revision
-      version = page.wiki_versions.order(:version_no).last
-
-      expect(page.body).to eq("a\nb")
-      expect(revision.lines_count).to eq(2)
-      expect(version.body).to eq("a\nb")
-      expect(version.reason).to eq('init')
     end
 
     it 'rejects body that becomes blank after normalisation' do
@@ -80,7 +73,7 @@ RSpec.describe Wiki::Commit do
       tag = create(:tag, primary_tag_name: tag_name, category: :general)
 
       page =
-          described_class.create_content!(
+          seed_wiki_page(
               tag_name:,
               body: 'before',
               created_by_user: user,

backend/spec/services/wiki/commit_spec.rb

@@ -1,12 +1,13 @@
 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_name, name: title)
 
-    Wiki::Commit.create_content!(
+    seed_wiki_page(
         tag_name:,
         body:,
         created_by_user: user,
@@ -84,7 +85,7 @@ RSpec.describe Wiki::Commit do
       tag = create(:tag, primary_tag_name: tag_name, category: :general)
 
       page =
-          described_class.create_content!(
+          seed_wiki_page(
               tag_name:,
               body: 'before',
               created_by_user: user,
@@ -111,7 +112,7 @@ RSpec.describe Wiki::Commit do
       tag = create(:tag, primary_tag_name: tag_name, category: :general)
 
       page =
-          described_class.create_content!(
+          seed_wiki_page(
               tag_name:,
               body: 'before',
               created_by_user: user,

backend/spec/services/wiki_version_recorder_spec.rb

@@ -1,10 +1,11 @@
 require 'rails_helper'
 
 RSpec.describe WikiVersionRecorder do
+  include WikiRecords
   let(:user) { create_member_user! }
 
   def create_page title:, body: 'body'
-    Wiki::Commit.create_content!(
+    seed_wiki_page(
         tag_name: create(:tag_name, name: title),
         body:,
         created_by_user: user,

backend/spec/support/wiki_records.rb

@@ -0,0 +1,20 @@
+# Historical records must remain seedable after application creation is frozen.
+module WikiRecords
+  def seed_wiki_page(tag_name:, body:, created_by_user:, message: nil)
+    page = WikiPage.create!(tag_name:, body:,
+                            created_user: created_by_user, updated_user: created_by_user)
+    revision = Wiki::Commit.legacy_content!(
+        page:, body:, created_user: created_by_user, message:)
+    if tag_name.tag && tag_name.language_code == 'ja'
+      TagDescription.create!(
+          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,
+          updated_by_user_id: created_by_user.id)
+      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

frontend/src/lib/help.test.ts

@@ -0,0 +1,56 @@
+import { describe, expect, it } from 'vitest'
+
+import { createHelpFixture } from '@/test/helpFixtures'
+
+
+describe ('Help file catalogue', () => {
+  it ('uses current_edition rather than the newest file, without YAML titles', async () => {
+    const { api } = createHelpFixture ()
+    expect (api.getHelpArticle ('guide')?.languages.ja.currentEdition).toBe ('2026-10-02')
+    expect (await api.getHelpSearchEntries ('ja')).toEqual ([
+	{ identifier: 'guide', edition: '2026-10-02',
+	  title: 'ホーム', body: '\nタグを検索する' },
+	{ identifier: '設定 手順', edition: '2026-10-03',
+	  title: '設定', body: '\nタグを設定する' }])
+  })
+
+  it ('orders same-day editions numerically and separates languages', () => {
+    const { api } = createHelpFixture ()
+    expect (api.getHelpEditions ('guide', 'ja')).toEqual ([
+	'2026-10-01', '2026-10-02', '2026-10-02.2', '2026-10-02.3', '2026-10-02.10'])
+    expect (api.getHelpEditions ('guide', 'en')).toEqual (['2026-10-02'])
+  })
+
+  it ('derives each edition title from its first H1', async () => {
+    const { api, raw } = createHelpFixture ()
+    expect (await api.getHelpEditionText ('guide', 'ja', '2026-10-01'))
+	.toEqual ({ title: '旧ホーム', body: '\n過去限定本文' })
+    raw['../../help/guide/editions/ja/2026-10-02.mdx']
+	.mockResolvedValue ('\uFEFF# 改題\r\n\r\n本文\r\n# 別見出し')
+    expect (await api.getHelpEditionText ('guide', 'ja', '2026-10-02'))
+	.toEqual ({ title: '改題', body: '\r\n本文\r\n# 別見出し' })
+  })
+
+  it ('returns missing resources without substituting another edition', async () => {
+    const { api } = createHelpFixture ()
+    expect (api.getHelpArticle ('absent')).toBeNull ()
+    expect (api.getHelpEditions ('absent', 'ja')).toEqual ([])
+    expect (await api.getHelpEdition ('guide', 'ja', 'missing')).toBeNull ()
+    expect (await api.getHelpEditionText ('guide', 'fr', '2026-10-02')).toBeNull ()
+  })
+
+  it ('rejects a missing current file instead of silently hiding an article', async () => {
+    const { api, raw } = createHelpFixture ()
+    delete raw['../../help/guide/editions/ja/2026-10-02.mdx']
+    await expect (api.getHelpSearchEntries ('ja')).rejects.toThrow ()
+  })
+
+  it ('reports raw loading failures and missing leading H1', async () => {
+    const { api, raw } = createHelpFixture ()
+    const loader = raw['../../help/guide/editions/ja/2026-10-02.mdx']
+    loader.mockRejectedValueOnce (new Error ('fixture failure'))
+    await expect (api.getHelpSearchEntries ('ja')).rejects.toThrow ('fixture failure')
+    loader.mockResolvedValueOnce ('本文\n# 遅い見出し')
+    await expect (api.getHelpEditionText ('guide', 'ja', '2026-10-02')).rejects.toThrow ()
+  })
+})

frontend/src/lib/helpPrefetch.test.tsx

@@ -0,0 +1,94 @@
+import { QueryClient } from '@tanstack/react-query'
+import { fireEvent, screen, waitFor } from '@testing-library/react'
+import { Route, Routes, useLocation } from 'react-router-dom'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import PrefetchLink from '@/components/PrefetchLink'
+import * as prefetchers from '@/lib/prefetchers'
+import HelpDetailPage from '@/pages/help/HelpDetailPage'
+import { helpFixture } from '@/test/helpFixtures'
+import { renderWithProviders } from '@/test/render'
+
+const settings = vi.hoisted (() => ({ linkPreload: 'intent' }))
+vi.mock ('@/lib/useClientBehaviourSettings', () => ({
+    useClientBehaviourSettings: () => settings }))
+vi.mock ('@/lib/help', async () => (await import ('@/test/helpFixtures')).helpFixture.api)
+
+
+const Location = () => {
+  const location = useLocation ()
+  return <output data-testid="location">{location.pathname}</output>
+}
+
+
+describe ('Help prefetch integration', () => {
+  beforeEach (() => {
+    settings.linkPreload = 'intent'
+    vi.clearAllMocks ()
+  })
+
+  it.each (['/help', '/help/guide', '/help/changes',
+      '/help/%E8%A8%AD%E5%AE%9A%20%E6%89%8B%E9%A0%86?edition=2026-10-03']) (
+      'registers a unique prefetcher for %s', path => {
+	const url = new URL (path, window.location.origin)
+	expect (prefetchers.routePrefetchers.filter (entry => entry.test (url))).toHaveLength (1)
+      })
+
+  it ('loads and reuses the same MDX module for repeated prefetch and display', async () => {
+    const client = new QueryClient ()
+    const loader = helpFixture.modules['../../help/guide/editions/ja/2026-10-02.mdx']
+    await Promise.all ([
+	prefetchers.prefetchForURL (client, '/help/guide'),
+	prefetchers.prefetchForURL (client, '/help/guide')])
+    expect (loader).toHaveBeenCalledTimes (1)
+    renderWithProviders (
+	<Routes><Route path="/help/:identifier" element={<HelpDetailPage/>}/></Routes>,
+	{ route: '/help/guide' })
+    await screen.findByRole ('heading', { name: 'ホーム' })
+    expect (loader).toHaveBeenCalledTimes (1)
+  })
+
+  it ('prefetches the requested identifier and edition independently', async () => {
+    const client = new QueryClient ()
+    await prefetchers.prefetchForURL (client, '/help/guide?edition=2026-10-02.3')
+    await prefetchers.prefetchForURL (client, `/help/${encodeURIComponent ('設定 手順')}`)
+    expect (helpFixture.modules['../../help/guide/editions/ja/2026-10-02.3.mdx'])
+	.toHaveBeenCalledTimes (1)
+    expect (helpFixture.modules['../../help/設定 手順/editions/ja/2026-10-03.mdx'])
+	.toHaveBeenCalledTimes (1)
+    expect (helpFixture.modules['../../help/guide/editions/en/2026-10-02.mdx'])
+	.not.toHaveBeenCalled ()
+  })
+
+  it ('loads history editions without treating changes as an article', async () => {
+    const article = vi.spyOn (helpFixture.api, 'getHelpArticle')
+    await prefetchers.prefetchForURL (new QueryClient (), '/help/changes')
+    expect (article).not.toHaveBeenCalledWith ('changes')
+    expect (helpFixture.raw['../../help/guide/editions/ja/2026-10-01.mdx'])
+	.toHaveBeenCalled ()
+  })
+
+  it.each (['intent', 'click', 'off']) ('respects %s intent settings and still prefetches clicks',
+      async mode => {
+	settings.linkPreload = mode
+	const run = vi.spyOn (prefetchers, 'prefetchForURL').mockResolvedValue ()
+	renderWithProviders (<><Location/><PrefetchLink to="/help/guide">Help</PrefetchLink></>)
+	const link = screen.getByRole ('link', { name: 'Help' })
+	fireEvent.mouseEnter (link)
+	fireEvent.touchStart (link)
+	expect (run).toHaveBeenCalledTimes (mode === 'intent' ? 2 : 0)
+	fireEvent.click (link)
+	await waitFor (() => expect (screen.getByTestId ('location'))
+	    .toHaveTextContent ('/help/guide'))
+	expect (run).toHaveBeenCalledTimes (mode === 'intent' ? 3 : 1)
+      })
+
+  it ('continues navigation after prefetch failure', async () => {
+    vi.spyOn (console, 'error').mockImplementation (() => {})
+    vi.spyOn (prefetchers, 'prefetchForURL').mockRejectedValue (new Error ('offline'))
+    renderWithProviders (<><Location/><PrefetchLink to="/help/guide">Help</PrefetchLink></>)
+    fireEvent.click (screen.getByRole ('link', { name: 'Help' }))
+    await waitFor (() => expect (screen.getByTestId ('location'))
+	.toHaveTextContent ('/help/guide'))
+  })
+})

frontend/src/lib/wiki.test.ts

@@ -2,9 +2,7 @@ import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import { fetchWikiPage, fetchWikiPageByTitle, fetchWikiPages } from '@/lib/wiki'
 
-const api = vi.hoisted (() => ({
+const api = vi.hoisted (() => ({ apiGet: vi.fn () }))
-  apiGet: vi.fn (),
-}))
 
 vi.mock ('@/lib/api', () => api)
 
@@ -21,28 +19,37 @@ describe ('wiki API functions', () => {
     await fetchWikiPage ('1', { version: '3' })
 
     expect (api.apiGet).toHaveBeenNthCalledWith (
-        1,
+	1,
-        '/wiki',
+	'/wiki',
-        { params: { title: '虹' } },
+	{ params: { title: '虹' } })
-    )
     expect (api.apiGet).toHaveBeenNthCalledWith (
-        2,
+	2,
-        '/wiki/1',
+	'/wiki/1',
-        { params: { version: '3' } },
+	{ params: { version: '3' } })
-    )
   })
 
   it ('encodes title path segments and returns null on misses', async () => {
     api.apiGet.mockResolvedValueOnce ({ id: 2 })
-    api.apiGet.mockRejectedValueOnce (new Error ('missing'))
+    api.apiGet.mockRejectedValueOnce ({ isAxiosError: true, response: { status: 404 } })
 
     await fetchWikiPageByTitle ('a/b c', { version: undefined })
-    await expect (fetchWikiPageByTitle ('missing', {})).resolves.toBeNull ()
+    await expect (fetchWikiPageByTitle ('missing', { })).resolves.toBeNull ()
 
     expect (api.apiGet).toHaveBeenNthCalledWith (
-        1,
+	1,
-        '/wiki/title/a%2Fb%20c',
+	'/wiki/title/a%2Fb%20c',
-        { params: { version: undefined } },
+	{ params: { version: undefined } })
-    )
+  })
+
+  it.each ([403, 500]) ('preserves HTTP %s errors', async status => {
+    const error = { isAxiosError: true, response: { status } }
+    api.apiGet.mockRejectedValueOnce (error)
+    await expect (fetchWikiPageByTitle ('ホーム', { })).rejects.toBe (error)
+  })
+
+  it ('preserves network failures for callers', async () => {
+    const error = new Error ('network failure')
+    api.apiGet.mockRejectedValueOnce (error)
+    await expect (fetchWikiPageByTitle ('ホーム', { })).rejects.toBe (error)
   })
 })

frontend/src/mdx-components.test.tsx

@@ -0,0 +1,77 @@
+import { fireEvent, screen, within } from '@testing-library/react'
+import { afterAll, describe, expect, it, vi } from 'vitest'
+import { Route, Routes } from 'react-router-dom'
+
+import HelpDetailPage from '@/pages/help/HelpDetailPage'
+import { compileMdx, transformMdx } from '@/test/compileMdx'
+import { helpFixture } from '@/test/helpFixtures'
+import { renderWithProviders } from '@/test/render'
+
+const prefetch = vi.hoisted (() => vi.fn (async () => {}))
+vi.hoisted (() => {
+  vi.stubGlobal ('Uint8Array', Object.getPrototypeOf (new TextEncoder ().encode ('')).constructor)
+})
+afterAll (() => vi.unstubAllGlobals ())
+vi.mock ('@/lib/prefetchers', () => ({ prefetchForURL: prefetch }))
+vi.mock ('@/lib/help', async () => (await import ('@/test/helpFixtures')).helpFixture.api)
+
+const tableSource = [
+    '# 表のある記事', '', '| 項目 | 説明 |', '| --- | --- |',
+    '| [ヘルプ](/help/guide) | **強調** |', '| 通常 | 本文 |'].join ('\n')
+
+
+describe ('Help MDX with the application compiler', () => {
+  it ('compiles GFM table structure, links and emphasis', async () => {
+    const Content = await compileMdx (tableSource)
+    renderWithProviders (<Content/>)
+    const table = screen.getByRole ('table')
+    expect (table.querySelector ('thead')).not.toBeNull ()
+    expect (table.querySelector ('tbody')).not.toBeNull ()
+    expect (within (table).getAllByRole ('columnheader')).toHaveLength (2)
+    expect (within (table).getAllByRole ('cell')).toHaveLength (4)
+    expect (within (table).getByRole ('link', { name: 'ヘルプ' }))
+	.toHaveAttribute ('href', '/help/guide')
+    expect (table.querySelector ('strong')).toHaveTextContent ('強調')
+  })
+
+  it ('retains headings, paragraphs and lists', async () => {
+    const Content = await compileMdx ('# 見出し\n\n本文\n\n- 第一\n- 第二')
+    renderWithProviders (<Content/>)
+    expect (screen.getByRole ('heading', { level: 1 })).toHaveTextContent ('見出し')
+    expect (screen.getByText ('本文').tagName).toBe ('P')
+    expect (screen.getAllByRole ('listitem')).toHaveLength (2)
+  })
+
+  it ('keeps tables inside the Help dark-mode typography container', async () => {
+    const Content = await compileMdx (tableSource)
+    vi.spyOn (helpFixture.api, 'getHelpEdition').mockResolvedValue (Content)
+    renderWithProviders (
+	<Routes><Route path="/help/:identifier" element={<HelpDetailPage/>}/></Routes>,
+	{ route: '/help/guide' })
+    const table = await screen.findByRole ('table')
+    expect (table.closest ('article')).toHaveClass ('prose', 'dark:prose-invert')
+  })
+
+  it ('contains wide tables in a horizontal scroll area', async () => {
+    const Content = await compileMdx (tableSource.replace ('通常', 'W'.repeat (200)))
+    vi.spyOn (helpFixture.api, 'getHelpEdition').mockResolvedValue (Content)
+    renderWithProviders (
+	<Routes><Route path="/help/:identifier" element={<HelpDetailPage/>}/></Routes>,
+	{ route: '/help/guide' })
+    const table = await screen.findByRole ('table')
+    expect (table.closest ('.overflow-x-auto, .overflow-x-scroll')).not.toBeNull ()
+  })
+
+  it.each (['.mdx?raw', '.mdx?url']) ('preserves the %s transform bypass', async suffix => {
+    expect (await transformMdx (tableSource, suffix)).toBeNull ()
+  })
+
+  it ('uses the common PrefetchLink interaction for internal MDX links', async () => {
+    prefetch.mockClear ()
+    const Content = await compileMdx ('[内部リンク](/help/guide)')
+    renderWithProviders (<Content/>)
+    fireEvent.mouseEnter (screen.getByRole ('link', { name: '内部リンク' }))
+    expect (prefetch).toHaveBeenCalledWith (expect.anything (),
+	new URL ('/help/guide', window.location.origin).href)
+  })
+})

frontend/src/pages/help/HelpChangesPage.test.tsx

@@ -0,0 +1,41 @@
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
+import { render, screen } from '@testing-library/react'
+import { HelmetProvider } from 'react-helmet-async'
+import { describe, expect, it, vi } from 'vitest'
+
+import { apiGet } from '@/lib/api'
+import App from '@/App'
+
+vi.hoisted (() => {
+  window.history.replaceState (null, '', '/help/changes')
+})
+
+vi.mock ('@/lib/help', async () => (await import ('@/test/helpFixtures')).helpFixture.api)
+vi.mock ('@/lib/api', () => ({ apiGet: vi.fn (), apiPost: async () => ({}),
+			    isApiError: () => false }))
+vi.mock ('@/components/TopNav', () => ({ default: () => null }))
+vi.mock ('@/components/DevModeWatermark', () => ({ default: () => null }))
+vi.mock ('@/lib/useClientBehaviourSettings', () => ({
+    useClientBehaviourSettings: () => ({ animation: 'off', linkPreload: 'off' }) }))
+
+
+describe ('Help global edition history', () => {
+  it ('routes /help/changes to published editions in date and numeric order', async () => {
+    const client = new QueryClient ({ defaultOptions: { queries: { retry: false } } })
+    const { container } = render (
+	<QueryClientProvider client={client}>
+	  <HelmetProvider><App/></HelmetProvider>
+	</QueryClientProvider>)
+    const links = await screen.findAllByRole ('link')
+    const editions = links.map (link => link.getAttribute ('href'))
+	.filter (href => href?.startsWith ('/help/') && href.includes ('edition='))
+    expect (editions).toEqual ([
+	`/help/${encodeURIComponent ('設定 手順')}?edition=2026-10-03`,
+	'/help/guide?edition=2026-10-02.10', '/help/guide?edition=2026-10-02.3',
+	'/help/guide?edition=2026-10-02.2', '/help/guide?edition=2026-10-02',
+	'/help/guide?edition=2026-10-01'])
+    expect (container).toHaveTextContent ('旧ホーム')
+    expect (apiGet).not.toHaveBeenCalled ()
+    expect (window.location.pathname).toBe ('/help/changes')
+  })
+})

frontend/src/pages/help/HelpDetailPage.test.tsx

@@ -0,0 +1,108 @@
+import { act, fireEvent, screen, waitFor } from '@testing-library/react'
+import { Route, Routes, useLocation, useNavigate } from 'react-router-dom'
+import { describe, expect, it, vi } from 'vitest'
+
+import HelpDetailPage from '@/pages/help/HelpDetailPage'
+import { helpFixture } from '@/test/helpFixtures'
+import { renderWithProviders } from '@/test/render'
+
+import type { ReactElement } from 'react'
+
+vi.mock ('@/lib/help', async () => (await import ('@/test/helpFixtures')).helpFixture.api)
+
+
+const Navigation = () => {
+  const navigate = useNavigate ()
+  const location = useLocation ()
+  return (
+      <>
+	<output data-testid="location">{location.pathname}{location.search}</output>
+	<button onClick={() => navigate ('/help/設定%20手順')}>switch article</button>
+	<button onClick={() => navigate ('/help/guide?edition=2026-10-02.3')}>
+	  switch edition
+	</button>
+      </>)
+}
+
+
+const renderDetail = (route = '/help/guide') => renderWithProviders (
+    <>
+      <Navigation/>
+      <Routes>
+	<Route path="/help/:identifier" element={<HelpDetailPage/>}/>
+      </Routes>
+    </>, { route })
+
+
+describe ('Help details', () => {
+  it ('displays current_edition H1 and body even when newer files exist', async () => {
+    renderDetail ()
+    expect (await screen.findByRole ('heading', { name: 'ホーム' })).toBeInTheDocument ()
+    expect (screen.getByText ('タグを検索する')).toBeInTheDocument ()
+    expect (screen.queryByText ('第十版本文')).not.toBeInTheDocument ()
+    await waitFor (() => expect (document.title).toContain ('ホーム ヘルプ'))
+  })
+
+  it ('uses the historical H1 in both page and document titles', async () => {
+    renderDetail ('/help/guide?edition=2026-10-01')
+    expect (await screen.findByRole ('heading', { name: '旧ホーム' })).toBeInTheDocument ()
+    expect (screen.getByText ('過去限定本文')).toBeInTheDocument ()
+    await waitFor (() => expect (document.title).toContain ('旧ホーム ヘルプ'))
+    expect (screen.getByText ('(最古)')).toBeInTheDocument ()
+    expect (screen.getByRole ('link', { name: '新 >' }))
+	.toHaveAttribute ('href', '/help/guide?edition=2026-10-02')
+  })
+
+  it ('navigates .2, .3 and .10 in numeric edition order', async () => {
+    renderDetail ('/help/guide?edition=2026-10-02.3')
+    await screen.findByRole ('heading', { name: 'ホーム第三版' })
+    expect (screen.getByRole ('link', { name: '< 古' }))
+	.toHaveAttribute ('href', '/help/guide?edition=2026-10-02.2')
+    const next = screen.getByRole ('link', { name: '新 >' })
+    expect (next).toHaveAttribute ('href', '/help/guide?edition=2026-10-02.10')
+    fireEvent.click (next)
+    await screen.findByRole ('heading', { name: 'ホーム第十版' })
+    expect (screen.getByText ('(最新)')).toBeInTheDocument ()
+    expect (screen.queryByText ('第三版本文')).not.toBeInTheDocument ()
+  })
+
+  it.each (['/help/missing', '/help/guide?edition=missing']) (
+      'shows NotFound without redirecting %s', async route => {
+	renderDetail (route)
+	expect (await screen.findByText ('404')).toBeInTheDocument ()
+	expect (screen.getByTestId ('location')).toHaveTextContent (route)
+      })
+
+  it ('hides the old body and title immediately while another article loads', async () => {
+    let finish!: (value: { default: () => ReactElement }) => void
+    const pending = new Promise<{ default: () => ReactElement }> (resolve => {
+      finish = resolve
+    })
+    helpFixture.modules['../../help/設定 手順/editions/ja/2026-10-03.mdx']
+	.mockReturnValueOnce (pending)
+    renderDetail ()
+    await screen.findByRole ('heading', { name: 'ホーム' })
+    fireEvent.click (screen.getByRole ('button', { name: 'switch article' }))
+    expect (screen.queryByText ('タグを検索する')).not.toBeInTheDocument ()
+    await waitFor (() => expect (document.title).not.toContain ('ホーム'))
+    await act (async () => finish ({ default: () => <h1>設定</h1> }))
+    await screen.findByRole ('heading', { name: '設定' })
+    await waitFor (() => expect (document.title).toContain ('設定 ヘルプ'))
+  })
+
+  it ('ignores a late response for the previous edition', async () => {
+    let finish!: (value: { default: () => ReactElement }) => void
+    const pending = new Promise<{ default: () => ReactElement }> (resolve => {
+      finish = resolve
+    })
+    helpFixture.modules['../../help/guide/editions/ja/2026-10-02.mdx']
+	.mockReturnValueOnce (pending)
+    renderDetail ()
+    fireEvent.click (screen.getByRole ('button', { name: 'switch edition' }))
+    await screen.findByRole ('heading', { name: 'ホーム第三版' })
+    await act (async () => finish ({ default: () => <h1>遅延した旧本文</h1> }))
+    expect (screen.queryByText ('遅延した旧本文')).not.toBeInTheDocument ()
+    expect (screen.getByRole ('heading', { name: 'ホーム第三版' })).toBeInTheDocument ()
+    await waitFor (() => expect (document.title).toContain ('ホーム第三版 ヘルプ'))
+  })
+})

frontend/src/pages/help/HelpListPage.test.tsx

@@ -0,0 +1,52 @@
+import { fireEvent, screen } from '@testing-library/react'
+import { describe, expect, it, vi } from 'vitest'
+
+import HelpListPage from '@/pages/help/HelpListPage'
+import { helpFixture } from '@/test/helpFixtures'
+import { renderWithProviders } from '@/test/render'
+
+vi.mock ('@/lib/help', async () => (await import ('@/test/helpFixtures')).helpFixture.api)
+
+
+describe ('Help search', () => {
+  it ('initially lists each current article once with encoded detail links', async () => {
+    renderWithProviders (<HelpListPage/>, { route: '/help' })
+    expect (await screen.findByRole ('link', { name: 'ホーム' }))
+	.toHaveAttribute ('href', '/help/guide')
+    expect (screen.getByRole ('link', { name: '設定' }))
+	.toHaveAttribute ('href', `/help/${encodeURIComponent ('設定 手順')}`)
+    expect (screen.getByText ('2 件')).toBeInTheDocument ()
+    expect (screen.queryByText ('旧ホーム')).not.toBeInTheDocument ()
+    expect (screen.queryByText ('ホーム第十版')).not.toBeInTheDocument ()
+  })
+
+  it.each ([
+      ['ホーム', '', ['ホーム']],
+      ['', '検索', ['ホーム']],
+      ['', 'タグ', ['ホーム', '設定']],
+      ['ホーム', '設定', []],
+      ['ホーム', '検索', ['ホーム']],
+      ['旧ホーム', '', []],
+      ['', '過去限定本文', []]]) (
+      'searches title %s and body %s together', async (title, body, expected) => {
+	const { container } = renderWithProviders (<HelpListPage/>)
+	await screen.findByText ('2 件')
+	fireEvent.change (screen.getByRole ('textbox', { name: 'タイトル' }), {
+	    target: { value: title } })
+	fireEvent.change (screen.getByRole ('textbox', { name: '内容' }), {
+	    target: { value: body } })
+	fireEvent.click (screen.getByRole ('button', { name: '検索' }))
+	expect (Array.from (container.querySelectorAll ('tbody a'), link => link.textContent))
+	    .toEqual (expected)
+	if (expected.length === 0)
+	  expect (screen.getByText ('該当する記事がありません．')).toBeInTheDocument ()
+      })
+
+  it ('displays loading failures without stale results', async () => {
+    helpFixture.raw['../../help/guide/editions/ja/2026-10-02.mdx']
+	.mockRejectedValueOnce (new Error ('fixture loading failed'))
+    renderWithProviders (<HelpListPage/>)
+    expect (await screen.findByRole ('alert')).toHaveTextContent ('fixture loading failed')
+    expect (screen.queryByRole ('link', { name: 'ホーム' })).not.toBeInTheDocument ()
+  })
+})

frontend/src/pages/wiki/WikiHelpCompatibility.test.tsx

@@ -0,0 +1,91 @@
+import { screen, waitFor } from '@testing-library/react'
+import { Route, Routes, useLocation } from 'react-router-dom'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import { apiGet } from '@/lib/api'
+import HelpDetailPage from '@/pages/help/HelpDetailPage'
+import WikiDetailPage from '@/pages/wiki/WikiDetailPage'
+import { buildWikiPage } from '@/test/factories'
+import { helpFixture } from '@/test/helpFixtures'
+import { renderWithProviders } from '@/test/render'
+
+vi.mock ('@/lib/api', () => ({ apiGet: vi.fn () }))
+vi.mock ('@/lib/help', async () => (await import ('@/test/helpFixtures')).helpFixture.api)
+vi.mock ('@/lib/tags', () => ({ fetchTagByName: async () => null }))
+vi.mock ('@/lib/posts', () => ({ fetchPosts: async () => ({ posts: [], count: 0 }) }))
+
+
+const Location = () => {
+  const location = useLocation ()
+  return <output data-testid="location">{location.pathname}{location.search}</output>
+}
+
+
+const renderWiki = (title: string) => {
+  const route = `/wiki/${encodeURIComponent (title)}`
+  renderWithProviders (
+      <>
+	<Location/>
+	<Routes>
+	  <Route path="/wiki/:title" element={<WikiDetailPage/>}/>
+	  <Route path="/help/:identifier" element={<HelpDetailPage/>}/>
+	  <Route path="/404" element={<div>unexpected redirect</div>}/>
+	</Routes>
+      </>, { route })
+  return route
+}
+
+
+describe ('Legacy Wiki to Help compatibility', () => {
+  beforeEach (() => {
+    vi.mocked (apiGet).mockReset ()
+    vi.mocked (apiGet).mockImplementation (async path => {
+      if (path === '/wiki')
+	return []
+      throw { isAxiosError: true, response: { status: 404 } }
+    })
+  })
+
+  it ('keeps a successful Wiki result even when Help has the same title', async () => {
+    vi.mocked (apiGet).mockResolvedValueOnce (buildWikiPage ({
+	title: 'ホーム', body: 'Wiki の現行本文' }))
+    const route = renderWiki ('ホーム')
+    await screen.findByText ('Wiki の現行本文')
+    expect (screen.getByTestId ('location')).toHaveTextContent (route)
+    expect (screen.queryByText ('タグを検索する')).not.toBeInTheDocument ()
+  })
+
+  it.each (['ホーム', 'ヘルプ:ホーム', '旧ホーム', 'ヘルプ:旧ホーム']) (
+      'redirects a unique current or historical Japanese title: %s', async title => {
+	renderWiki (title)
+	await waitFor (() => {
+	  expect (screen.getByTestId ('location')).toHaveTextContent ('/help/guide')
+	})
+	expect (await screen.findByRole ('heading', { name: 'ホーム' })).toBeInTheDocument ()
+	expect (apiGet).toHaveBeenCalledWith (
+	    `/wiki/title/${encodeURIComponent (title)}`, expect.anything ())
+      })
+
+  it ('keeps the original URL and displays NotFound when no title matches', async () => {
+    const route = renderWiki ('該当なし')
+    await screen.findByText ('404')
+    expect (screen.getByTestId ('location')).toHaveTextContent (route)
+    expect (screen.queryByText ('unexpected redirect')).not.toBeInTheDocument ()
+  })
+
+  it ('does not choose between articles with the same title', async () => {
+    const loader = helpFixture.raw['../../help/設定 手順/editions/ja/2026-10-03.mdx']
+    loader.mockResolvedValueOnce ('# ホーム\n\n別の記事')
+    const route = renderWiki ('ホーム')
+    await screen.findByText ('404')
+    expect (screen.getByTestId ('location')).toHaveTextContent (route)
+  })
+
+  it.each ([403, 500]) ('does not redirect HTTP %s to Help', async status => {
+    vi.mocked (apiGet).mockRejectedValueOnce ({ isAxiosError: true, response: { status } })
+    const route = renderWiki ('ホーム')
+    await waitFor (() => expect (apiGet).toHaveBeenCalled ())
+    expect (screen.getByTestId ('location')).toHaveTextContent (route)
+    expect (screen.queryByText ('タグを検索する')).not.toBeInTheDocument ()
+  })
+})

frontend/src/test/compileMdx.ts

@@ -0,0 +1,37 @@
+import * as jsxRuntime from 'react/jsx-runtime'
+import { ModuleKind, ScriptTarget, transpileModule } from 'typescript'
+
+import { useMDXComponents } from '@/mdx-components'
+import viteConfig from '../../vite.config'
+
+import type { ComponentType } from 'react'
+
+type Transform = (source: string, id: string) => Promise<{ code: string } | null>
+
+
+export const transformMdx = async (source: string, suffix = '.mdx') => {
+  const plugins = viteConfig.plugins?.flat () as { name: string; transform: Transform }[]
+  const plugin = plugins.find (entry => entry.name === '@mdx-js/rollup')
+  if (plugin == null)
+    throw new Error ('The application MDX compiler is not registered')
+  return plugin.transform.call (plugin, source, `/test/help-table${suffix}`)
+}
+
+
+export const compileMdx = async (source: string): Promise<ComponentType> => {
+  const result = await transformMdx (source)
+  if (result == null)
+    throw new Error ('MDX was not compiled')
+  const code = transpileModule (result.code, {
+      compilerOptions: { module: ModuleKind.CommonJS, target: ScriptTarget.ES2022 } }).outputText
+  const exports = { } as { default: ComponentType }
+  const requireFixture = (name: string) => {
+    if (name === 'react/jsx-runtime')
+      return jsxRuntime
+    if (name === '@/mdx-components')
+      return { useMDXComponents }
+    throw new Error (`Unexpected MDX dependency: ${name}`)
+  }
+  new Function ('require', 'exports', code) (requireFixture, exports)
+  return exports.default
+}

frontend/src/test/helpFixtures.tsx

@@ -0,0 +1,60 @@
+import { createElement } from 'react'
+import { ModuleKind, ScriptTarget, transpileModule } from 'typescript'
+import { vi } from 'vitest'
+import { parse } from 'yaml'
+
+import source from '@/lib/help.ts?raw'
+
+import type { ReactElement } from 'react'
+
+import type * as Help from '@/lib/help'
+
+export const editionRows = [
+    ['guide', 'ja', '2026-10-01', '旧ホーム', '過去限定本文'],
+    ['guide', 'ja', '2026-10-02', 'ホーム', 'タグを検索する'],
+    ['guide', 'ja', '2026-10-02.2', 'ホーム第二版', '第二版本文'],
+    ['guide', 'ja', '2026-10-02.3', 'ホーム第三版', '第三版本文'],
+    ['guide', 'ja', '2026-10-02.10', 'ホーム第十版', '第十版本文'],
+    ['guide', 'en', '2026-10-02', 'Home', 'English body'],
+    ['設定 手順', 'ja', '2026-10-03', '設定', 'タグを設定する']] as const
+
+const compiled = transpileModule (source.replaceAll ('import.meta', 'helpMeta'), {
+    compilerOptions: { module: ModuleKind.CommonJS, target: ScriptTarget.ES2022 } }).outputText
+
+
+// Replace Vite's file-discovery boundary, executing the actual Help module.
+export const createHelpFixture = () => {
+  const articles: Record<string, string> = {
+      '../../help/guide/article.yml':
+	'identifier: guide\nlanguages:\n  ja:\n    current_edition: 2026-10-02\n'
+	+ '  en:\n    current_edition: 2026-10-02\n',
+      '../../help/設定 手順/article.yml':
+	'identifier: 設定 手順\nlanguages:\n  ja:\n    current_edition: 2026-10-03\n' }
+  const raw = Object.fromEntries (editionRows.map (([id, language, edition, title, body]) => [
+      `../../help/${id}/editions/${language}/${edition}.mdx`,
+      vi.fn (async () => `# ${title}\n\n${body}`)]))
+  const modules = Object.fromEntries (editionRows.map (([id, language, edition, title, body]) => [
+      `../../help/${id}/editions/${language}/${edition}.mdx`,
+      vi.fn (async (): Promise<{ default: () => ReactElement }> => ({
+	  default: () => createElement ('div', null,
+	      createElement ('h1', null, title), createElement ('p', null, body)) }))]))
+  const glob = (pattern: string, options?: { query?: string }) => {
+    if (pattern.endsWith ('article.yml'))
+      return articles
+    if (pattern.endsWith ('*.mdx'))
+      return options?.query === '?raw' ? raw : modules
+    throw new Error (`Unexpected Help glob: ${pattern}`)
+  }
+  const api = { } as typeof Help
+  const requireFixture = (name: string) => {
+    if (name === 'yaml')
+      return { parse }
+    throw new Error (`Unexpected Help dependency: ${name}`)
+  }
+  new Function ('require', 'exports', 'helpMeta', compiled) (
+      requireFixture, api, { glob })
+  return { api, articles, raw, modules }
+}
+
+
+export const helpFixture = createHelpFixture ()

frontend/vite.config.ts

@@ -1,9 +1,11 @@
 import mdx from '@mdx-js/rollup'
 import react from '@vitejs/plugin-react'
 import path from 'path'
+import remarkGFM from 'remark-gfm'
 import { defineConfig } from 'vite'
 
-const mdxPlugin = mdx ({ providerImportSource: '@/mdx-components' })
+const mdxPlugin = mdx ({ providerImportSource: '@/mdx-components',
+			 remarkPlugins: [remarkGFM] })
 const originalTransform = mdxPlugin.transform
 
 if (typeof originalTransform === 'function')