#428

backend/spec/models/locale_spec.rb

@@ -67,20 +67,18 @@ RSpec.describe Locale, type: :model do
         primary_flg: true, auto_generated: false)
   end
 
-  it 'creates a primary name when the language has only an alias' do
-    prepare_ainu_reference!
-    tag = create(:tag, primary_name: 'alias_only_tag')
-    alias_name = create(:tag_name, :alias, name: 'alias_en',
-                                          tag:,
-                                          language_code: 'ain', script_code: 'Kana')
+  it 'adds the new language primary while preserving existing names and aliases' do
+    tag = create(:tag, primary_name: 'named_tag')
+    create(:tag_name, :alias, name: 'existing_alias', tag:,
+                              language_code: 'ja', script_code: 'Jpan')
+    original_names = tag.tag_names.order(:id).map(&:attributes)
 
     create_ainu_locale!
 
-    expect(alias_name.reload).to have_attributes(
-        tag_id: tag.id,
-        language_code: 'ain', script_code: 'Kana', primary_flg: false)
+    expect(tag.tag_names.where(language_code: 'ja').order(:id).map(&:attributes))
+        .to eq(original_names)
     generated = TagName.find_by!(tag_id: tag.id, language_code: 'ain', primary_flg: true)
-    expect(generated).to have_attributes(tag_id: tag.id, language_code: 'ain',
+    expect(generated).to have_attributes(name: 'named_tag', tag_id: tag.id, language_code: 'ain',
                                          script_code: 'Kana', primary_flg: true,
                                          auto_generated: true)
     expect(TagName.where(tag_id: tag.id, language_code: 'ain', primary_flg: true).count).to eq(1)

backend/spec/models/tag_name_sanitisation_rule_spec.rb

@@ -113,6 +113,8 @@ RSpec.describe TagNameSanitisationRule, type: :model do
       it 'renames without merging tags or deleting either language identity' do
         locale
         nipponese = create(:tag, primary_name: 'foobar')
+        primary_tag_name_for(nipponese, 'ain').update!(
+            name: 'different_ainu_name', auto_generated: false)
         ainu_name = create(:tag_name, name: 'temporary',
                                         language_code: 'ain', script_code: 'Kana')
         ainu = create(:tag, primary_tag_name: ainu_name)

backend/spec/models/tag_spec.rb

@@ -66,7 +66,7 @@ RSpec.describe Tag, type: :model do
     it 'canonicalises aliases in the supplied language only' do
       prepare_ainu_reference!
       nipponese = create(:tag, primary_name: 'nipponese_canonical')
-      ainu_name = create(:tag_name, name: 'ainu_canonical',
+      ainu_name = build(:tag_name, tag: nil, name: 'ainu_canonical',
                                       language_code: 'ain', script_code: 'Kana')
       ainu = create(:tag, primary_tag_name: ainu_name)
       primary_tag_name_for(ainu, 'ja').update!(
@@ -265,7 +265,7 @@ RSpec.describe Tag, type: :model do
         expect(tag.category).to eq('character')
       end
 
-      it 'uses a Japanese fallback for an Ainu-origin tag without reverse transcription' do
+      it 'copies an Ainu-origin name to Japanese without reverse transcription' do
         locale
         allow(TagName).to receive(:generate_name).and_call_original
 
@@ -277,9 +277,9 @@ RSpec.describe Tag, type: :model do
                 name: 'ainu_origin', auto_generated: false))
         expect(TagName.where(tag:, language_code: 'ja', primary_flg: true))
             .to contain_exactly(have_attributes(
-                name: "Tag_##{ tag.id }", auto_generated: true))
+                name: 'ainu_origin', auto_generated: true))
         expect(TagName).to have_received(:generate_name)
-            .with(Locale.nipponese, tag, nil)
+            .with(Locale.nipponese, tag, tag.tag_name('ain'))
       end
 
       it 'gives a new tag one primary name for every active language' do

backend/spec/requests/locale_write_paths_spec.rb

@@ -153,11 +153,14 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
     let(:ainu_name) do
       create(:tag_name, name: 'shared_name', language_code: 'ain', script_code: 'Kana')
     end
-    let(:ainu_tag) { create(:tag, primary_tag_name: ainu_name, category: :material) }
+    let(:ainu_tag) do
+      create(:tag, primary_tag_name: ainu_name, category: :material).tap do |tag|
+        primary_tag_name_for(tag, 'ja').update!(name: 'ainu_in_japanese', auto_generated: false)
+      end
+    end
     let(:nipponese_tag) do
       create(:tag, primary_name: 'temporary_nipponese', category: :general).tap do |tag|
-        # Isolate lookup from the separately tested uniqueness validation.
-        primary_tag_name_for(tag, 'ja').update_columns(name: 'shared_name')
+        primary_tag_name_for(tag, 'ja').update!(name: 'shared_name')
       end
     end
 
@@ -291,6 +294,8 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
     it 'allows a rename to a name already used in Nipponese' do
       locale
       nipponese = create(:tag, primary_name: 'rename_target')
+      primary_tag_name_for(nipponese, 'ain').update!(
+          name: 'different_ainu_target', auto_generated: false)
 
       patch "/tags/#{ tag.id }", params: { locale: 'ain-Kana', name: 'rename_target' }
 

backend/spec/requests/posts_spec.rb

@@ -2323,8 +2323,10 @@ RSpec.describe 'Posts API', type: :request do
         'prev' => nil
       )
       expect(latest.fetch('tags')).to include(
-        { 'name' => 'spec_tag_2', 'type' => 'added' },
-        { 'name' => 'spec_tag', 'type' => 'removed' }
+        { 'name' => 'spec_tag_2', 'restore_name' => 'spec_tag_2',
+          'external' => false, 'type' => 'added' },
+        { 'name' => 'spec_tag', 'restore_name' => 'spec_tag',
+          'external' => false, 'type' => 'removed' }
       )
       expect(latest.fetch('original_created_from')).to eq(
         'current' => oc_from.iso8601,
@@ -2351,7 +2353,8 @@ RSpec.describe 'Posts API', type: :request do
         'prev' => nil
       )
       expect(first.fetch('tags')).to include(
-        { 'name' => 'spec_tag', 'type' => 'added' }
+        { 'name' => 'spec_tag', 'restore_name' => 'spec_tag',
+          'external' => false, 'type' => 'added' }
       )
       expect(first.fetch('created_at')).to eq(t_v1.iso8601)
     end
@@ -2435,7 +2438,9 @@ RSpec.describe 'Posts API', type: :request do
       expect(response).to have_http_status(:ok)
       expect(json.fetch('count')).to eq(3)
       expect(json.fetch('versions').first.fetch('tags')).to include(
-          'name' => primary_tag_name_for(tag2, 'ja').name, 'type' => 'context')
+          'name' => primary_tag_name_for(tag2, 'ja').name,
+          'restore_name' => primary_tag_name_for(tag2, 'ja').name,
+          'external' => false, 'type' => 'context')
     end
 
     it 'filters versions by tag when the current snapshot includes the tag' do
@@ -2449,7 +2454,8 @@ RSpec.describe 'Posts API', type: :request do
       expect(versions[0]['post_id']).to eq(post_record.id)
       expect(versions[0]['version_no']).to eq(2)
       expect(versions[0]['tags']).to include(
-        { 'name' => 'spec_tag_2', 'type' => 'added' }
+        { 'name' => 'spec_tag_2', 'restore_name' => 'spec_tag_2',
+          'external' => false, 'type' => 'added' }
       )
     end
 
@@ -2467,10 +2473,12 @@ RSpec.describe 'Posts API', type: :request do
       first = versions[1]
 
       expect(latest['tags']).to include(
-        { 'name' => 'spec_tag', 'type' => 'removed' }
+        { 'name' => 'spec_tag', 'restore_name' => 'spec_tag',
+          'external' => false, 'type' => 'removed' }
       )
       expect(first['tags']).to include(
-        { 'name' => 'spec_tag', 'type' => 'added' }
+        { 'name' => 'spec_tag', 'restore_name' => 'spec_tag',
+          'external' => false, 'type' => 'added' }
       )
     end
 

backend/spec/services/post_create_plan_spec.rb

@@ -18,9 +18,9 @@ RSpec.describe PostCreatePlan do
       ainu_name = create(:tag_name, name: 'shared_name',
                                       language_code: 'ain', script_code: 'Kana')
       ainu = create(:tag, primary_tag_name: ainu_name, category: :character)
+      primary_tag_name_for(ainu, 'ja').update!(name: 'ainu_in_japanese', auto_generated: false)
       nipponese = create(:tag, primary_name: 'temporary_nipponese', category: :general)
-      # The DB permits this identity; validation has its own contract spec.
-      primary_tag_name_for(nipponese, 'ja').update_columns(name: 'shared_name')
+      primary_tag_name_for(nipponese, 'ja').update!(name: 'shared_name')
       ainu_parent_name = create(:tag_name, name: 'ainu_parent',
                                             language_code: 'ain', script_code: 'Kana')
       ainu_parent = create(:tag, primary_tag_name: ainu_parent_name,

backend/spec/services/shared_resource_id_allocator_mysql_spec.rb

@@ -141,6 +141,40 @@ RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
     result(first)
   end
 
+  [false, true].each do |inner_rollback|
+    [false, true].each do |outer_rollback|
+      it "keeps savepoint=#{ inner_rollback } lock through outer rollback=#{ outer_rollback }" do
+        connection = ApplicationRecord.connection
+        database = connection.pool.db_config.database
+        lock_name = "btrc:ids:#{ Digest::SHA256.hexdigest(database)[0, 16] }:tags"
+        quoted_lock = connection.quote(lock_name)
+        owner = connection.select_value('SELECT CONNECTION_ID()').to_i
+
+        connection.transaction do
+          connection.transaction(requires_new: true) do
+            create_resource(:external)
+            raise ActiveRecord::Rollback if inner_rollback
+          end
+
+          expect(connection.select_value("SELECT IS_USED_LOCK(#{ quoted_lock })").to_i)
+              .to eq(owner)
+          contender = worker do |other|
+            other.select_value("SELECT GET_LOCK(#{ quoted_lock }, 0)").to_i
+          end
+          expect(result(contender)).to eq(0)
+
+          SharedResourceIdAllocator.lock_space!(ExternalTag, 'tags')
+          raise ActiveRecord::Rollback if outer_rollback
+        end
+
+        expect(connection.select_value("SELECT IS_FREE_LOCK(#{ quoted_lock })").to_i)
+            .to eq(1)
+        expect(ExternalTag.exists?(name: "#{ @prefix }_external"))
+            .to eq(!inner_rollback && !outer_rollback)
+      end
+    end
+  end
+
   it 'raises on a real lock acquisition failure without inserting a record' do
     first, (_id, _connection_id, lock_name) = hold_creation(:external, rollback: true)
     stub_const('SharedResourceIdAllocator::LOCK_TIMEOUT', 0)

backend/spec/services/shared_resource_id_allocator_spec.rb

@@ -101,7 +101,7 @@ RSpec.describe SharedResourceIdAllocator, 'lock lifecycle' do
   let(:record) { build(:external_tag) }
   let(:connection) { double('connection') }
   let(:transaction) { double('transaction', open?: true) }
-  let(:callbacks) { { } }
+  let(:callbacks) { [] }
   let(:sql) { [] }
 
   before do
@@ -128,19 +128,24 @@ RSpec.describe SharedResourceIdAllocator, 'lock lifecycle' do
       end
     end
     allow(ExternalTag).to receive(:connection).and_return(connection)
-    allow(ExternalTag).to receive(:current_transaction).and_return(transaction)
+    allow(connection).to receive(:current_transaction).and_return(transaction)
+    allow(connection).to receive(:add_transaction_record) { callbacks << _1 }
+    allow(connection).to receive(:disconnect!)
     allow(ExternalTag).to receive(:uncached).and_yield
-    [:after_commit, :after_rollback].each do |event|
-      allow(transaction).to receive(event) { |&callback| callbacks[event] = callback }
-    end
   end
 
-  [:after_commit, :after_rollback].each do |event|
+  def finish_transaction event
+    allow(transaction).to receive(:open?).and_return(false)
+    callbacks.shift.public_send(event)
+    allow(transaction).to receive(:open?).and_return(true)
+  end
+
+  [:committed!, :rolledback!].each do |event|
     it "holds the shared lock until #{ event }" do
       described_class.assign!(record)
       expect(record.id).to eq(9)
       expect(sql.grep(/RELEASE_LOCK/)).to be_empty
-      callbacks.fetch(event).call
+      finish_transaction(event)
       expect(sql.grep(/RELEASE_LOCK/).size).to eq(1)
     end
   end
@@ -155,7 +160,7 @@ RSpec.describe SharedResourceIdAllocator, 'lock lifecycle' do
   it 'releases a successfully acquired lock when allocation fails and rolls back' do
     allow(connection).to receive(:select_all).and_raise('query failed')
     expect { described_class.assign!(record) }.to raise_error(RuntimeError, 'query failed')
-    callbacks.fetch(:after_rollback).call
+    finish_transaction(:rolledback!)
     expect(sql.grep(/RELEASE_LOCK/).size).to eq(1)
   end
 
@@ -164,18 +169,17 @@ RSpec.describe SharedResourceIdAllocator, 'lock lifecycle' do
     described_class.assign!(record)
     expect(record.id).to eq(50)
     expect(sql.grep(/FOR UPDATE/)).to be_empty
-    callbacks.fetch(:after_commit).call
+    finish_transaction(:committed!)
   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|
       allow(model).to receive(:connection).and_return(connection)
-      allow(model).to receive(:current_transaction).and_return(transaction)
       allow(model).to receive(:uncached).and_yield
       record = model.new(id: 50)
       described_class.assign!(record)
       statement = sql.grep(/GET_LOCK/).last
-      callbacks.fetch(:after_commit).call
+      finish_transaction(:committed!)
       statement
     end
     expect(locks[0]).to eq(locks[1])
@@ -187,7 +191,21 @@ RSpec.describe SharedResourceIdAllocator, 'lock lifecycle' do
   it 'reports lock release failures' do
     described_class.assign!(record)
     allow(connection).to receive(:select_value).with(/RELEASE_LOCK/).and_return(nil)
-    expect { callbacks.fetch(:after_commit).call }
+    expect { finish_transaction(:committed!) }
         .to raise_error(ActiveRecord::ActiveRecordError, /lock release failed/)
+    expect(connection).to have_received(:disconnect!)
+  end
+
+  it 'keeps the lock and transfers cleanup when a savepoint rolls back' do
+    described_class.assign!(record)
+    callbacks.shift.rolledback!
+
+    expect(callbacks.size).to eq(1)
+    expect(sql.grep(/RELEASE_LOCK/)).to be_empty
+    described_class.assign!(record)
+    expect(sql.grep(/GET_LOCK/).size).to eq(1)
+
+    finish_transaction(:committed!)
+    expect(sql.grep(/RELEASE_LOCK/).size).to eq(1)
   end
 end

backend/spec/services/tag_name_transcription_spec.rb

@@ -17,7 +17,7 @@ RSpec.describe TagNameTranscription do
       'ガギグゲゴダヂヅデド' => 'カキクケコタチチュテト',
       'バビブベボパピプペポ' => 'パピプペポパピプペポ',
       'ザジズゼゾ' => 'チャチチュチェチョ',
-      'ジャジュジョ' => 'チヤチユチヨ',
+      'ジャジュジョ' => 'チャチュチョ',
       'アㇰアㇱアッアンアㇺアㇷ゚' => 'アㇰアㇱアッアンアㇺアㇷ゚',
       'アㇻイㇼウㇽエㇾオㇿ' => 'アㇻイㇼウㇽエㇾオㇿ',
       '漢Aあ' => 'カンAア' }.each do |source, expected|
@@ -26,9 +26,12 @@ RSpec.describe TagNameTranscription do
     end
   end
 
-  ['😀', 'ヴ', 'ティ', 'ㇵ', '魑', '𠮷', 'ー', '々'].each do |source|
-    it "rejects unsupported input #{ source }" do
-      expect { described_class.ainu(source) }.to raise_error(described_class::Unconvertible)
+  { '😀' => '', 'ヴ' => '', 'ティ' => 'テ', 'ㇵ' => '',
+    '魑' => '', '𠮷' => '', 'ー' => '', '々' => '',
+    'ア😀😀イ' => 'ア_イ', '😀アイ😀' => 'アイ',
+    '_😀_' => '__', 'ア_😀_イ' => 'ア___イ', '漢魑字' => 'カン_チ' }.each do |source, expected|
+    it "preserves convertible portions of #{ source }" do
+      expect(described_class.ainu(source)).to eq(expected)
     end
   end
 end

backend/spec/services/tag_version_recorder_spec.rb

@@ -64,7 +64,7 @@ RSpec.describe TagVersionRecorder do
   it 'snapshots future languages together without a request locale argument' do
     prepare_ainu_names!
 
-    version = described_class.record!(tag:, event_type: :create, created_by_user: user)
+    version = described_class.record!(tag:, event_type: :update, created_by_user: user)
 
     expect(version.names).to eq(
         'ja' => nipponese_snapshot,
@@ -75,12 +75,12 @@ RSpec.describe TagVersionRecorder do
 
   it 'creates a version for an Ainu-only change and preserves prior names' do
     prepare_ainu_names!
-    original = described_class.record!(tag:, event_type: :create, created_by_user: user)
+    original = described_class.record!(tag:, event_type: :update, created_by_user: user)
     primary_tag_name_for(tag, 'ain').update!(name: 'Renamed')
 
     updated = described_class.record!(tag:, event_type: :update, created_by_user: user)
 
-    expect(updated.version_no).to eq(2)
+    expect(updated.version_no).to eq(original.version_no + 1)
     expect(original.reload.names.fetch('ain')).to include('name' => 'Ainu name')
     expect(updated.names.fetch('ain')).to include('name' => 'Renamed')
     expect(updated.names.fetch('ja')).to eq(nipponese_snapshot)
@@ -88,11 +88,11 @@ RSpec.describe TagVersionRecorder do
 
   it 'does not create a version for an unchanged multilingual snapshot' do
     prepare_ainu_names!
-    described_class.record!(tag:, event_type: :create, created_by_user: user)
+    original = described_class.record!(tag:, event_type: :update, created_by_user: user)
 
     unchanged = described_class.record!(tag:, event_type: :update, created_by_user: user)
 
-    expect(unchanged.version_no).to eq(1)
-    expect(tag.reload.tag_versions.count).to eq(1)
+    expect(unchanged.version_no).to eq(original.version_no)
+    expect(tag.reload.tag_versions.count).to eq(original.version_no)
   end
 end

frontend/src/components/ErrorScreen.test.tsx

@@ -1,5 +1,6 @@
 import { render, screen } from '@testing-library/react'
 import { HelmetProvider } from 'react-helmet-async'
+import { MemoryRouter } from 'react-router-dom'
 import { describe, expect, it } from 'vitest'
 
 import ErrorScreen from '@/components/ErrorScreen'
@@ -12,9 +13,9 @@ describe ('ErrorScreen', () => {
     [503, '鯖死んでるよ（泣）'],
   ]) ('renders status %s', (status, message) => {
     render (
-        <HelmetProvider>
+        <MemoryRouter><HelmetProvider>
           <ErrorScreen status={status}/>
-        </HelmetProvider>,
+        </HelmetProvider></MemoryRouter>,
     )
 
     expect (screen.getByText (String (status))).toBeInTheDocument ()
@@ -24,9 +25,9 @@ describe ('ErrorScreen', () => {
 
   it ('throws for unsupported statuses', () => {
     expect (() => render (
-        <HelmetProvider>
+        <MemoryRouter><HelmetProvider>
           <ErrorScreen status={418}/>
-        </HelmetProvider>,
+        </HelmetProvider></MemoryRouter>,
     )).toThrow ()
   })
 })

frontend/src/components/PostEditForm.test.tsx

@@ -1,8 +1,10 @@
-import { fireEvent, render, screen, waitFor } from '@testing-library/react'
+import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { describe, expect, it, vi } from 'vitest'
 
+import { textContentOf } from '@/test/text'
 import PostEditForm from '@/components/PostEditForm'
 import { buildPost, buildTag } from '@/test/factories'
+import { renderWithProviders as render } from '@/test/render'
 
 const postsApi = vi.hoisted (() => ({
   updatePost: vi.fn (),
@@ -19,7 +21,8 @@ const toastApi = vi.hoisted (() => ({
 vi.mock ('@/lib/posts', () => postsApi)
 vi.mock ('@/lib/api', () => api)
 vi.mock ('@/components/ui/use-toast', () => toastApi)
-vi.mock ('@/lib/dialogues/useDialogue', () => ({
+vi.mock ('@/lib/dialogues/useDialogue', async importOriginal => ({
+  ...await importOriginal<typeof import ('@/lib/dialogues/useDialogue')> (),
   default: () => ({
     choice: vi.fn (),
   }),
@@ -60,11 +63,12 @@ describe ('PostEditForm', () => {
             parentPostIds: '3 4',
             tags:          'general-tag',
           }),
-          { baseVersionNo: 4 },
+          { baseVersionNo: 4 }, 'ja',
       )
     })
     expect (onSave).toHaveBeenCalledWith (expect.objectContaining ({ versionNo: 5 }))
-    expect (toastApi.toast).toHaveBeenCalledWith ({ description: '更新しました．' })
+    expect (toastApi.toast).toHaveBeenCalledTimes (1)
+    expect (textContentOf (toastApi.toast.mock.calls[0][0].description)).toBe ('更新しました．')
   })
 
   it ('preserves duration while the video tag is temporarily removed', () => {
@@ -78,7 +82,7 @@ describe ('PostEditForm', () => {
 
     render (<PostEditForm post={post} onSave={vi.fn ()}/>)
 
-    expect (screen.getByText ('動画時間').parentElement?.querySelector ('input'))
+    expect (screen.getByDisplayValue ('180.5'))
 	.toHaveValue ('180.5')
 
     const tags = screen.getAllByRole ('textbox')[2]
@@ -88,7 +92,7 @@ describe ('PostEditForm', () => {
     fireEvent.change (tags, {
       target: { value: '動画 general-tag' },
     })
-    expect (screen.getByText ('動画時間').parentElement?.querySelector ('input'))
+    expect (screen.getByDisplayValue ('180.5'))
 	.toHaveValue ('180.5')
   })
 

frontend/src/components/PostEmbed.test.tsx

@@ -1,8 +1,9 @@
-import { fireEvent, render, screen, waitFor } from '@testing-library/react'
+import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import PostEmbed from '@/components/PostEmbed'
 import { buildPost } from '@/test/factories'
+import { renderWithProviders as render } from '@/test/render'
 
 const dialogue = vi.hoisted (() => ({
   confirm: vi.fn (),
@@ -12,8 +13,9 @@ const nicoViewer = vi.hoisted (() => ({
   props: vi.fn (),
 }))
 
-vi.mock ('@/components/dialogues/DialogueProvider', () => ({
-  useDialogue: () => dialogue,
+vi.mock ('@/lib/dialogues/useDialogue', async importOriginal => ({
+  ...await importOriginal<typeof import ('@/lib/dialogues/useDialogue')> (),
+  default: () => dialogue,
 }))
 
 vi.mock ('@/components/NicoViewer', () => ({

frontend/src/components/PostFormTagsArea.test.tsx

@@ -26,7 +26,8 @@ describe ('PostFormTagsArea', () => {
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenCalledWith (
           '/tags/autocomplete',
-          { params: { q: '虹', nico: '0' } },
+          { locale: 'ja', params: { q: '虹', nico: '0' },
+	    signal: expect.any (AbortSignal) },
       )
     })
     expect (setTags).toHaveBeenCalledWith ('虹夏')

frontend/src/components/PostList.test.tsx

@@ -26,11 +26,11 @@ describe ('PostList', () => {
 
     expect (screen.getByRole ('link', { name: 'First' })).toHaveAttribute (
         'href',
-        '/posts/1',
+        '/ja/posts/1',
     )
     expect (
         screen.getByRole ('link', { name: 'https://example.com/second' }),
-    ).toHaveAttribute ('href', '/posts/2')
+    ).toHaveAttribute ('href', '/ja/posts/2')
   })
 
   it ('calls the optional click handler', () => {

frontend/src/components/PostOriginalCreatedTimeField.test.tsx

@@ -1,7 +1,8 @@
-import { fireEvent, render, screen } from '@testing-library/react'
+import { fireEvent, screen } from '@testing-library/react'
 import { describe, expect, it, vi } from 'vitest'
 
 import PostOriginalCreatedTimeField from '@/components/PostOriginalCreatedTimeField'
+import { renderWithProviders as render } from '@/test/render'
 
 describe ('PostOriginalCreatedTimeField', () => {
   it ('updates from and before values', () => {

frontend/src/components/SortHeader.test.tsx

@@ -17,7 +17,7 @@ describe ('SortHeader', () => {
 
     expect (screen.getByRole ('link', { name: 'タイトル ▲' })).toHaveAttribute (
         'href',
-        '/posts?tags=x&page=1&order=title%3Adesc',
+        '/ja/posts?tags=x&page=1&order=title%3Adesc',
     )
   })
 
@@ -33,7 +33,7 @@ describe ('SortHeader', () => {
 
     expect (screen.getByRole ('link', { name: '更新' })).toHaveAttribute (
         'href',
-        '/posts?page=1&order=updated_at%3Adesc',
+        '/ja/posts?page=1&order=updated_at%3Adesc',
     )
   })
 })

frontend/src/components/TagLink.test.tsx

@@ -13,7 +13,7 @@ describe ('TagLink', () => {
 
     expect (screen.getByRole ('link', { name: '虹 夏' })).toHaveAttribute (
         'href',
-        '/posts?tags=%E8%99%B9+%E5%A4%8F',
+        '/ja/posts?tags=%E8%99%B9+%E5%A4%8F',
     )
     expect (screen.getByText ('4')).toBeInTheDocument ()
   })
@@ -40,7 +40,7 @@ describe ('TagLink', () => {
 
     expect (screen.getByRole ('link', { name: '?' })).toHaveAttribute (
         'href',
-        '/wiki/a%2Fb',
+        '/ja/wiki/a%2Fb',
     )
   })
 

frontend/src/components/TopNavUser.test.tsx

@@ -17,7 +17,7 @@ describe ('TopNavUser', () => {
 
     expect (screen.getByRole ('link', { name: '山田' })).toHaveAttribute (
         'href',
-        '/users/settings',
+        '/ja/users/settings',
     )
   })
 

frontend/src/components/common/Pagination.test.tsx

@@ -13,11 +13,11 @@ describe ('Pagination', () => {
 
     expect (screen.getByLabelText ('前のページ')).toHaveAttribute (
         'href',
-        '/posts?tags=abc&page=2',
+        '/ja/posts?tags=abc&page=2',
     )
     expect (screen.getByLabelText ('次のページ')).toHaveAttribute (
         'href',
-        '/posts?tags=abc&page=4',
+        '/ja/posts?tags=abc&page=4',
     )
     expect (screen.getByText ('3')).toHaveAttribute ('aria-current', 'page')
   })
@@ -33,6 +33,6 @@ describe ('Pagination', () => {
 
     rerender (<Pagination page={1} totalPages={2}/>)
 
-    expect (screen.getByLabelText ('次のページ')).toHaveAttribute ('href', '/tags?page=2')
+    expect (screen.getByLabelText ('次のページ')).toHaveAttribute ('href', '/ja/tags?page=2')
   })
 })

frontend/src/components/common/TagInput.test.tsx

@@ -1,8 +1,9 @@
-import { fireEvent, render, screen, waitFor } from '@testing-library/react'
+import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import TagInput from '@/components/common/TagInput'
 import { buildTag } from '@/test/factories'
+import { renderWithProviders as render } from '@/test/render'
 
 const api = vi.hoisted (() => ({
   apiGet: vi.fn (),
@@ -26,7 +27,8 @@ describe ('TagInput', () => {
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenCalledWith (
           '/tags/autocomplete',
-          { params: { q: '虹夏', nico: '0' } },
+          { locale: 'ja', params: { q: '虹夏', nico: '0' },
+	    signal: expect.any (AbortSignal) },
       )
     })
     expect (setValue).toHaveBeenCalledWith ('ぼっち 虹夏')
@@ -53,7 +55,8 @@ describe ('TagInput', () => {
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenCalledWith (
           '/tags/autocomplete',
-          { params: { q: '虹夏', nico: '1' } },
+          { locale: 'ja', params: { q: '虹夏', nico: '1' },
+	    signal: expect.any (AbortSignal) },
       )
     })
   })

frontend/src/components/dialogues/DialogueProvider.test.tsx

@@ -1,6 +1,7 @@
 import { useCallback, useEffect } from 'react'
 import { fireEvent, render, screen, waitFor } from '@testing-library/react'
 import { describe, expect, it, vi } from 'vitest'
+import { MemoryRouter } from 'react-router-dom'
 
 import DialogueProvider from '@/components/dialogues/DialogueProvider'
 import useDialogue from '@/lib/dialogues/useDialogue'
@@ -49,7 +50,7 @@ describe ('DialogueProvider', () => {
 	  </button>)
     }
 
-    render (<DialogueProvider><Launcher/></DialogueProvider>)
+    render (<MemoryRouter><DialogueProvider><Launcher/></DialogueProvider></MemoryRouter>)
     fireEvent.click (screen.getByRole ('button', { name: '開く' }))
 
     expect (screen.getByText ('一件目')).toBeInTheDocument ()
@@ -73,7 +74,7 @@ describe ('DialogueProvider', () => {
 	  </button>)
     }
 
-    render (<DialogueProvider><Launcher/></DialogueProvider>)
+    render (<MemoryRouter><DialogueProvider><Launcher/></DialogueProvider></MemoryRouter>)
     fireEvent.click (screen.getByRole ('button', { name: '開く' }))
 
     const dialogue = screen.getByRole ('dialog')
@@ -101,7 +102,7 @@ describe ('DialogueProvider', () => {
 	  </button>)
     }
 
-    render (<DialogueProvider><Launcher/></DialogueProvider>)
+    render (<MemoryRouter><DialogueProvider><Launcher/></DialogueProvider></MemoryRouter>)
     fireEvent.click (screen.getByRole ('button', { name: '開く' }))
     const action = await screen.findByRole ('button', { name: '左操作' })
     fireEvent.click (action)

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

@@ -1,8 +1,9 @@
-import { fireEvent, render, screen, waitFor } from '@testing-library/react'
+import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { HelmetProvider } from 'react-helmet-async'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import SidebarComponent from '@/components/layout/SidebarComponent'
+import { renderWithProviders as render } from '@/test/render'
 
 
 const sidebarWidth = (element: Element | null): string =>

frontend/src/components/posts/PostCreationDataFieldsUsage.test.tsx

@@ -1,7 +1,8 @@
-import { render, screen } from '@testing-library/react'
+import { screen } from '@testing-library/react'
 import { describe, expect, it, vi } from 'vitest'
 
 import { buildPostImportRow } from '@/test/postImportFactories'
+import { renderWithProviders as render } from '@/test/render'
 
 import type { DialogueFormControls } from '@/lib/dialogues/useDialogue'
 

frontend/src/components/posts/PostThumbnailPreview.test.tsx

@@ -1,7 +1,8 @@
-import { fireEvent, render, screen } from '@testing-library/react'
+import { fireEvent, screen } from '@testing-library/react'
 import { describe, expect, it } from 'vitest'
 
 import PostThumbnailPreview from '@/components/posts/PostThumbnailPreview'
+import { renderWithProviders as render } from '@/test/render'
 
 describe ('PostThumbnailPreview', () => {
   it ('keeps an existing blob preview URL unchanged for normal post forms', () => {

frontend/src/components/posts/import/PostImportRowForm.test.tsx

@@ -1,8 +1,10 @@
-import { act, render, screen, waitFor } from '@testing-library/react'
+import { act, screen, waitFor } from '@testing-library/react'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import PostImportRowForm from '@/components/posts/import/PostImportRowForm'
 import { buildPostImportRow } from '@/test/postImportFactories'
+import { renderWithProviders as render } from '@/test/render'
+import { textContentOf } from '@/test/text'
 
 import type { DialogueFormAction, DialogueFormControls } from '@/lib/dialogues/useDialogue'
 
@@ -37,7 +39,7 @@ describe ('PostImportRowForm', () => {
     const titleInput = screen.getByDisplayValue ('manual title')
 
     await waitFor (() => expect (actions.at (-1)?.length).toBe (2))
-    const reset = actions.at (-1)?.find (action => action.label === '変更をリセット')
+    const reset = actions.at (-1)?.find (action => textContentOf (action.label) === '変更をリセット')
     expect (reset).toMatchObject ({ placement: 'start', variant: 'danger', disabled: false })
     await act (async () => {
       await reset?.onSelect ()
@@ -47,7 +49,7 @@ describe ('PostImportRowForm', () => {
     expect (titleInput).toHaveValue ('')
     expect (onSave).not.toHaveBeenCalled ()
 
-    const save = actions.at (-1)?.find (action => action.label === '編輯内容を保存')
+    const save = actions.at (-1)?.find (action => textContentOf (action.label) === '編輯内容を保存')
     await act (async () => {
       await save?.onSelect ()
     })
@@ -76,7 +78,7 @@ describe ('PostImportRowForm', () => {
     await waitFor (() => expect (actions.length).toBe (2))
 
     await act (async () => {
-      await actions.find (action => action.label === '変更をリセット')?.onSelect ()
+      await actions.find (action => textContentOf (action.label) === '変更をリセット')?.onSelect ()
     })
 
     expect (screen.getByDisplayValue ('manual title')).toBeInTheDocument ()
@@ -124,7 +126,7 @@ describe ('PostImportRowForm', () => {
     await waitFor (() => expect (actions.length).toBe (2))
 
     await act (async () => {
-      void actions.find (action => action.label === '編輯内容を保存')?.onSelect ()
+      void actions.find (action => textContentOf (action.label) === '編輯内容を保存')?.onSelect ()
     })
 
     expect (onSave).toHaveBeenCalledWith ({
@@ -171,7 +173,7 @@ describe ('PostImportRowForm', () => {
     expect (screen.getByDisplayValue ('tag1')).toBeInTheDocument ()
 
     await act (async () => {
-      await actions.find (action => action.label === '編輯内容を保存')?.onSelect ()
+      await actions.find (action => textContentOf (action.label) === '編輯内容を保存')?.onSelect ()
     })
 
     expect (onSave).toHaveBeenCalledWith ({
@@ -218,7 +220,8 @@ describe ('PostImportRowForm', () => {
             onSave={vi.fn ()}/>)
     await waitFor (() => expect (actions.length).toBe (2))
 
-    expect (actions.find (action => action.label === '変更をリセット')?.disabled).toBe (false)
+    const reset = actions.find (action => textContentOf (action.label) === '変更をリセット')
+    expect (reset?.disabled).toBe (false)
   })
 
   it (
@@ -249,7 +252,8 @@ describe ('PostImportRowForm', () => {
 
     let savePromise: Promise<boolean | void> | undefined
     await act (async () => {
-      savePromise = actions.find (action => action.label === '編輯内容を保存')?.onSelect ()
+      const save = actions.find (action => textContentOf (action.label) === '編輯内容を保存')
+      savePromise = save?.onSelect ()
     })
 
     await waitFor (() => {

frontend/src/components/posts/import/PostImportThumbnailPreview.test.tsx

@@ -1,7 +1,8 @@
-import { fireEvent, render, screen } from '@testing-library/react'
+import { fireEvent, screen } from '@testing-library/react'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import PostImportThumbnailPreview from '@/components/posts/import/PostImportThumbnailPreview'
+import { renderWithProviders as render } from '@/test/render'
 
 describe ('PostImportThumbnailPreview', () => {
   beforeEach (() => {

frontend/src/lib/gekanator.test.ts

@@ -52,7 +52,7 @@ describe('Gekanator API functions', () => {
     mockedApiGet.mockResolvedValueOnce({ posts })
 
     await expect(fetchGekanatorPosts()).resolves.toEqual(posts)
-    expect(mockedApiGet).toHaveBeenCalledWith('/gekanator/posts')
+    expect(mockedApiGet).toHaveBeenCalledWith('/gekanator/posts', { locale: 'ja' })
   })
 
   it('returns questions from the Gekanator questions endpoint', async () => {
@@ -60,7 +60,7 @@ describe('Gekanator API functions', () => {
     mockedApiGet.mockResolvedValueOnce({ questions })
 
     await expect(fetchGekanatorQuestions()).resolves.toEqual(questions)
-    expect(mockedApiGet).toHaveBeenCalledWith('/gekanator/questions')
+    expect(mockedApiGet).toHaveBeenCalledWith('/gekanator/questions', { locale: 'ja' })
   })
 })
 
@@ -458,7 +458,7 @@ describe('Gekanator API writers', () => {
           original_answer: 'partial',
         },
       ],
-    })
+    }, { locale: 'ja' })
   })
 
   it('sends question suggestions using snake_case request keys', async () => {
@@ -482,7 +482,7 @@ describe('Gekanator API writers', () => {
       gekanator_game_id: 100,
       question_text: '喜多ちゃんが泣いてる?',
       answer: 'yes',
-    })
+    }, { locale: 'ja' })
   })
 
   it('sends extra question answers using snake_case request keys', async () => {
@@ -517,7 +517,7 @@ describe('Gekanator API writers', () => {
             answer: 'probably_no',
           },
         ],
-      },
+      }, { locale: 'ja' },
     )
   })
 })

frontend/src/lib/helpPrefetch.test.tsx

@@ -43,7 +43,7 @@ describe ('Help prefetch integration', () => {
 	  <PrefetchLink to="/help/guide">Help</PrefetchLink>
 	  <Routes>
 	    <Route path="/" element={null}/>
-	    <Route path="/help/:identifier" element={<HelpDetailPage/>}/>
+	    <Route path="/ja/help/:identifier" element={<HelpDetailPage/>}/>
 	  </Routes>
 	</>)
     const loader = helpFixture.moduleLoads['../../help/guide/editions/ja/2026-10-02.10.mdx']
@@ -84,14 +84,14 @@ describe ('Help prefetch integration', () => {
 	  <PrefetchLink to={path}>diff</PrefetchLink>
 	  <Routes>
 	    <Route path="/" element={null}/>
-	    <Route path="/help/:identifier/diff" element={<HelpDiffPage/>}/>
+	    <Route path="/ja/help/:identifier/diff" element={<HelpDiffPage/>}/>
 	  </Routes>
 	</>)
     await Promise.all ([prefetchers.prefetchForURL (queryClient, path),
 	prefetchers.prefetchForURL (queryClient, path)])
     fireEvent.click (screen.getByRole ('link', { name: 'diff' }))
     expect (await screen.findByRole ('link', { name: '旧ホーム (2026-10-01)' }))
-	.toHaveAttribute ('href', '/help/guide?edition=2026-10-01')
+	.toHaveAttribute ('href', '/ja/help/guide?edition=2026-10-01')
     expect (screen.getByText ('+ # ホーム第十版')).toBeInTheDocument ()
     Object.entries (helpFixture.raw).forEach (([name, load]) => {
       const expected = /\/ja\/(2026-10-01|2026-10-02\.10)\.mdx$/.test (name) ? 1 : 0

frontend/src/lib/prefetchers.test.ts

@@ -21,6 +21,8 @@ const wikiApi = vi.hoisted (() => ({
   fetchWikiPage:        vi.fn (),
   fetchWikiPageByTitle: vi.fn (),
   fetchWikiPages:       vi.fn (),
+  fetchWikiPageByReference: vi.fn (),
+  fetchWikiAutolinkCandidates: vi.fn (),
 }))
 
 vi.mock ('@/lib/posts', () => postsApi)
@@ -45,12 +47,14 @@ describe ('prefetchForURL', () => {
     wikiApi.fetchWikiPages.mockResolvedValue ([])
     wikiApi.fetchWikiPage.mockResolvedValue ({ id: 1 })
     wikiApi.fetchWikiPageByTitle.mockResolvedValue (null)
+    wikiApi.fetchWikiPageByReference.mockResolvedValue (null)
+    wikiApi.fetchWikiAutolinkCandidates.mockResolvedValue ([])
   })
 
   it ('prefetches post indexes from query parameters', async () => {
     await prefetchForURL (
         qc (),
-        'http://localhost/posts?tags=a+b&match=any&page=2&limit=5&order=title%3Aasc',
+        '/ja/posts?tags=a+b&match=any&page=2&limit=5&order=title%3Aasc',
     )
 
     expect (postsApi.fetchPosts).toHaveBeenCalledWith (
@@ -60,20 +64,20 @@ describe ('prefetchForURL', () => {
           page:  2,
           limit: 5,
           order: 'title:asc',
-        }),
+        }), 'ja',
     )
   })
 
   it ('prefetches post detail pages', async () => {
-    await prefetchForURL (qc (), 'http://localhost/posts/12')
+    await prefetchForURL (qc (), '/ja/posts/12')
 
-    expect (postsApi.fetchPost).toHaveBeenCalledWith ('12')
+    expect (postsApi.fetchPost).toHaveBeenCalledWith ('12', 'ja')
   })
 
   it ('prefetches tag indexes from query parameters', async () => {
     await prefetchForURL (
         qc (),
-        'http://localhost/tags?post=9&name=x&category=general&page=4&post_count_lte=10',
+        '/ja/tags?post=9&name=x&category=general&page=4&post_count_lte=10',
     )
 
     expect (tagsApi.fetchTags).toHaveBeenCalledWith (
@@ -83,17 +87,17 @@ describe ('prefetchForURL', () => {
           category:     'general',
           page:         4,
           postCountLTE: 10,
-        }),
+        }), 'ja',
     )
   })
 
   it ('prefetches nico tag indexes and their alias from query parameters', async () => {
     await prefetchForURL (
         qc (),
-        'http://localhost/tags/nico?name=source&linked_tag=destination'
+        '/ja/tags/nico?name=source&linked_tag=destination'
 	    + '&link_status=linked&page=3&limit=10',
     )
-    await prefetchForURL (qc (), 'http://localhost/nico/tags?page=2')
+    await prefetchForURL (qc (), '/ja/nico/tags?page=2')
 
     expect (tagsApi.fetchNicoTags).toHaveBeenNthCalledWith (1, {
       name:       'source',
@@ -102,7 +106,7 @@ describe ('prefetchForURL', () => {
       page:       3,
       limit:      10,
       order:      'updated_at:desc',
-    })
+    }, 'ja')
     expect (tagsApi.fetchNicoTags).toHaveBeenNthCalledWith (2, {
       name:       '',
       linkedTag:  '',
@@ -110,28 +114,29 @@ describe ('prefetchForURL', () => {
       page:       2,
       limit:      20,
       order:      'updated_at:desc',
-    })
+    }, 'ja')
   })
 
   it ('prefetches wiki show pages and related tag/post data', async () => {
-    wikiApi.fetchWikiPageByTitle.mockResolvedValueOnce ({
+    wikiApi.fetchWikiPageByReference.mockResolvedValueOnce ({
       id:    3,
       title: 'Actual',
       body:  'body',
     })
 
-    await prefetchForURL (qc (), 'http://localhost/wiki/Alias')
+    await prefetchForURL (qc (), '/ja/wiki/Alias')
 
-    expect (wikiApi.fetchWikiPageByTitle).toHaveBeenCalledWith ('Alias', { version: undefined })
-    expect (wikiApi.fetchWikiPage).toHaveBeenCalledWith ('3', {})
-    expect (tagsApi.fetchTagByName).toHaveBeenCalledWith ('Actual')
+    expect (wikiApi.fetchWikiPageByReference).toHaveBeenCalledWith (
+	'Alias', { version: undefined }, 'ja')
+    expect (wikiApi.fetchWikiPage).not.toHaveBeenCalled ()
+    expect (tagsApi.fetchTagByName).toHaveBeenCalledWith ('Actual', 'ja')
     expect (postsApi.fetchPosts).toHaveBeenCalledWith (
-        expect.objectContaining ({ tags: 'Actual', limit: 8 }),
+        expect.objectContaining ({ tags: 'Actual', limit: 8 }), 'ja',
     )
   })
 
   it ('ignores routes without a prefetcher', async () => {
-    await prefetchForURL (qc (), 'http://localhost/unknown')
+    await prefetchForURL (qc (), '/ja/unknown')
 
     expect (postsApi.fetchPosts).not.toHaveBeenCalled ()
     expect (tagsApi.fetchTags).not.toHaveBeenCalled ()
@@ -141,14 +146,14 @@ describe ('prefetchForURL', () => {
   it ('prefetches external tag post history without treating it as an internal tag', async () => {
     await prefetchForURL (
 	qc (),
-	'http://localhost/posts/changes?external_tag=12&page=2&limit=50',
+	'/ja/posts/changes?external_tag=12&page=2&limit=50',
     )
 
     expect (postsApi.fetchPostChanges).toHaveBeenCalledWith ({
       externalTag: '12',
       page:        2,
       limit:       50,
-    })
+    }, 'ja')
 
     expect (tagsApi.fetchTag).not.toHaveBeenCalled ()
   })

frontend/src/mdx-components.test.tsx

@@ -32,7 +32,7 @@ describe ('Help MDX with the application compiler', () => {
     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')
+	.toHaveAttribute ('href', '/ja/help/guide')
     expect (table.querySelector ('strong')).toHaveTextContent ('強調')
   })
 
@@ -72,6 +72,6 @@ describe ('Help MDX with the application compiler', () => {
     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)
+	new URL ('/ja/help/guide', window.location.origin).href)
   })
 })

frontend/src/pages/deerjikists/DeerjikistDetailPage.test.tsx

@@ -63,7 +63,7 @@ describe ('DeerjikistDetailPage', () => {
     await waitFor (() => {
       expect (api.apiPut).toHaveBeenCalledWith (
           '/tags/7/deerjikists',
-          [{ platform: null, code: 'abc' }],
+          [{ platform: null, code: 'abc' }], { locale: 'ja' },
       )
     })
     expect (await screen.findByText ('プラットフォームを入力してください．')).toBeInTheDocument ()

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

@@ -8,7 +8,7 @@ import App from '@/App'
 import { helpFixture } from '@/test/helpFixtures'
 
 vi.hoisted (() => {
-  window.history.replaceState (null, '', '/help/changes')
+  window.history.replaceState (null, '', '/ja/help/changes')
 })
 
 vi.mock ('@/lib/help', async () => (await import ('@/test/helpFixtures')).helpFixture.api)
@@ -21,7 +21,10 @@ vi.mock ('@/lib/useClientBehaviourSettings', () => ({
 
 
 describe ('Help global edition history', () => {
-  beforeEach (() => helpFixture.reset ())
+  beforeEach (() => {
+    helpFixture.reset ()
+    vi.mocked (apiGet).mockResolvedValue ({ locales: [{ code: 'ja', name: '日本語' }] })
+  })
 
   it ('routes /help/changes to published editions in date and numeric order', async () => {
     const client = new QueryClient ({ defaultOptions: { queries: { retry: false } } })
@@ -31,12 +34,12 @@ describe ('Help global edition history', () => {
 	</QueryClientProvider>)
     const links = await screen.findAllByRole ('link')
     const editions = links.map (link => link.getAttribute ('href'))
-	.filter (href => href?.startsWith ('/help/') && href.includes ('edition='))
+	.filter (href => href?.startsWith ('/ja/help/') && href.includes ('edition='))
     expect (editions).toEqual ([
-	`/help/${encodeURIComponent ('設定 手順')}?edition=2026-10-03`,
-	'/help/guide?edition=2026-10-02.10', '/help/guide?edition=2026-10-02.3',
-	'/help/guide?edition=2026-10-02.2', '/help/guide?edition=2026-10-02',
-	'/help/guide?edition=2026-10-01'])
+	`/ja/help/${encodeURIComponent ('設定 手順')}?edition=2026-10-03`,
+	'/ja/help/guide?edition=2026-10-02.10', '/ja/help/guide?edition=2026-10-02.3',
+	'/ja/help/guide?edition=2026-10-02.2', '/ja/help/guide?edition=2026-10-02',
+	'/ja/help/guide?edition=2026-10-01'])
     expect (container).toHaveTextContent ('旧ホーム')
     expect (screen.getAllByRole ('columnheader').map (cell => cell.textContent))
 	.toEqual (['差分', 'タイトル', '有効開始年月日'])
@@ -45,11 +48,11 @@ describe ('Help global edition history', () => {
     expect (container.textContent).not.toMatch (/\d{1,2}:\d{2}/)
     expect (screen.getAllByRole ('link', { name: '差分' }).map (link =>
 	link.getAttribute ('href'))).toEqual ([
-	'/help/guide/diff?from=2026-10-02.3&to=2026-10-02.10',
-	'/help/guide/diff?from=2026-10-02.2&to=2026-10-02.3',
-	'/help/guide/diff?from=2026-10-02&to=2026-10-02.2',
-	'/help/guide/diff?from=2026-10-01&to=2026-10-02'])
-    expect (apiGet).not.toHaveBeenCalled ()
-    expect (window.location.pathname).toBe ('/help/changes')
+	'/ja/help/guide/diff?from=2026-10-02.3&to=2026-10-02.10',
+	'/ja/help/guide/diff?from=2026-10-02.2&to=2026-10-02.3',
+	'/ja/help/guide/diff?from=2026-10-02&to=2026-10-02.2',
+	'/ja/help/guide/diff?from=2026-10-01&to=2026-10-02'])
+    expect (apiGet).toHaveBeenCalledWith ('/locales')
+    expect (window.location.pathname).toBe ('/ja/help/changes')
   })
 })

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

@@ -17,19 +17,19 @@ const Navigation = () => {
   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')}>
+	<button onClick={() => navigate ('/ja/help/設定%20手順')}>switch article</button>
+	<button onClick={() => navigate ('/ja/help/guide?edition=2026-10-02.3')}>
 	  switch edition
 	</button>
       </>)
 }
 
 
-const renderDetail = (route = '/help/guide') => renderWithProviders (
+const renderDetail = (route = '/ja/help/guide') => renderWithProviders (
     <>
       <Navigation/>
       <Routes>
-	<Route path="/help/:identifier" element={<HelpDetailPage/>}/>
+	<Route path="/ja/help/:identifier" element={<HelpDetailPage/>}/>
       </Routes>
     </>, { route })
 
@@ -39,7 +39,7 @@ describe ('Help details', () => {
 
   it.each (['2026-10-02', '2026-10-02.2', '2026-10-02.3', '2026-10-02.10']) (
       'displays a date without inventing a time for edition %s', async edition => {
-	const { container } = renderDetail (`/help/guide?edition=${ edition }`)
+	const { container } = renderDetail (`/ja/help/guide?edition=${ edition }`)
 	await screen.findByRole ('heading')
 	expect (container).toHaveTextContent ('10月2日')
 	expect (container).not.toHaveTextContent ('Invalid Date')
@@ -61,31 +61,31 @@ describe ('Help details', () => {
   })
 
   it ('uses the historical H1 in both page and document titles', async () => {
-    renderDetail ('/help/guide?edition=2026-10-01')
+    renderDetail ('/ja/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')
+	.toHaveAttribute ('href', '/ja/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')
+    renderDetail ('/ja/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')
+	.toHaveAttribute ('href', '/ja/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')
+    expect (next).toHaveAttribute ('href', '/ja/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',
-      '/help/guide?edition=2026-02-30', '/help/guide?edition=2026-10-02.2.extra',
-      '/help/guide?edition=2026-10-02.11']) (
+  it.each (['/ja/help/missing', '/ja/help/guide?edition=missing',
+      '/ja/help/guide?edition=2026-02-30', '/ja/help/guide?edition=2026-10-02.2.extra',
+      '/ja/help/guide?edition=2026-10-02.11']) (
       'shows NotFound without redirecting %s', async route => {
 	renderDetail (route)
 	expect (await screen.findByText ('404')).toBeInTheDocument ()

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

@@ -14,9 +14,9 @@ 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: 'ホーム第十版' }))
-	.toHaveAttribute ('href', '/help/guide')
+	.toHaveAttribute ('href', '/ja/help/guide')
     expect (screen.getByRole ('link', { name: '設定' }))
-	.toHaveAttribute ('href', `/help/${encodeURIComponent ('設定 手順')}`)
+	.toHaveAttribute ('href', `/ja/help/${encodeURIComponent ('設定 手順')}`)
     expect (screen.getByText ('2 件')).toBeInTheDocument ()
     expect (screen.queryByText ('旧ホーム')).not.toBeInTheDocument ()
     expect (screen.queryByText ('未公開ホーム')).not.toBeInTheDocument ()
@@ -82,7 +82,7 @@ describe ('Help search', () => {
 	renderWithProviders (<HelpListPage/>, { route: `/help?${ params }` })
 	await screen.findByText (`${ found ? 1 : 0 } 件`)
 	if (found)
-	  expect (screen.getByRole ('link', { name: title })).toHaveAttribute ('href', '/help/guide')
+	  expect (screen.getByRole ('link', { name: title })).toHaveAttribute ('href', '/ja/help/guide')
 	else
 	  expect (screen.queryByRole ('link', { name: title })).not.toBeInTheDocument ()
 	expect (entry).toEqual ({ identifier: 'guide', edition: '2026-10-02.10',
@@ -99,7 +99,7 @@ describe ('Help search', () => {
 	    route: `/help?order=title:${ direction }` })
 	await screen.findByText ('2 件')
 	const expected = direction === 'asc'
-	    ? ['/help/beta', '/help/alpha'] : ['/help/alpha', '/help/beta']
+	    ? ['/ja/help/beta', '/ja/help/alpha'] : ['/ja/help/alpha', '/ja/help/beta']
 	expect (Array.from (container.querySelectorAll ('tbody a'), link =>
 	    link.getAttribute ('href'))).toEqual (expected)
       })
@@ -113,7 +113,7 @@ describe ('Help search', () => {
 	    route: `/help?order=title:${ direction }` })
 	await screen.findByText ('2 件')
 	expect (Array.from (container.querySelectorAll ('tbody a'), link =>
-	    link.getAttribute ('href'))).toEqual (['/help/alpha', '/help/beta'])
+	    link.getAttribute ('href'))).toEqual (['/ja/help/alpha', '/ja/help/beta'])
       })
 
   it.each (['asc', 'desc']) ('ignores title case before identifier ties in order %s',
@@ -125,6 +125,6 @@ describe ('Help search', () => {
 	    route: `/help?order=title:${ direction }` })
 	await screen.findByText ('2 件')
 	expect (Array.from (container.querySelectorAll ('tbody a'), link =>
-	    link.getAttribute ('href'))).toEqual (['/help/alpha', '/help/beta'])
+	    link.getAttribute ('href'))).toEqual (['/ja/help/alpha', '/ja/help/beta'])
       })
 })

frontend/src/pages/materials/MaterialDetailPage.test.tsx

@@ -2,6 +2,7 @@ import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { Route, Routes } from 'react-router-dom'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
+import { textContentOf } from '@/test/text'
 import MaterialDetailPage from '@/pages/materials/MaterialDetailPage'
 import { buildMaterial, buildTag } from '@/test/factories'
 import { renderWithProviders } from '@/test/render'
@@ -59,7 +60,7 @@ describe ('MaterialDetailPage', () => {
     renderPage ()
 
     await waitFor (() => {
-      expect (api.apiGet).toHaveBeenCalledWith ('/materials/8')
+      expect (api.apiGet).toHaveBeenCalledWith ('/materials/8', { locale: 'ja' })
     })
     expect (await screen.findByAltText ('素材タグ')).toHaveAttribute ('src', 'image.png')
   })
@@ -82,13 +83,15 @@ describe ('MaterialDetailPage', () => {
     fireEvent.click (screen.getByRole ('button', { name: '更新' }))
 
     await waitFor (() => {
-      expect (api.apiPut).toHaveBeenCalledWith ('/materials/8', expect.any (FormData))
+      expect (api.apiPut).toHaveBeenCalledWith (
+	  '/materials/8', expect.any (FormData), { locale: 'ja' })
     })
     const formData = api.apiPut.mock.calls[0]?.[1] as FormData
     expect (formData.get ('tag')).toBe ('new')
     expect (formData.get ('url')).toBe ('https://example.com/ref')
     expect (formData.get ('export_paths[legacy_drive]')).toBe ('素材/new.png')
-    expect (toastApi.toast).toHaveBeenCalledWith ({ title: '更新成功!' })
+    expect (toastApi.toast).toHaveBeenCalledTimes (1)
+    expect (textContentOf (toastApi.toast.mock.calls[0][0].title)).toBe ('更新成功!')
   })
 
   it ('shows not found when material API returns 404', async () => {
@@ -97,7 +100,7 @@ describe ('MaterialDetailPage', () => {
 
     renderPage ()
 
-    expect (await screen.findByText ('素材が見つかりませんでした．')).toBeInTheDocument ()
+    expect (await screen.findByText ('404')).toBeInTheDocument ()
   })
 
   it ('shows an error for non-404 material API failures', async () => {

frontend/src/pages/materials/MaterialListPage.test.tsx

@@ -23,7 +23,7 @@ describe ('MaterialListPage', () => {
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenCalledWith (
           '/materials',
-          { params: {
+          { locale: 'ja', params: {
               tag_state:  'all',
               media_kind: 'all',
               sort:       'created_at',
@@ -53,8 +53,9 @@ describe ('MaterialListPage', () => {
     renderWithProviders (<MaterialListPage/>, { route: '/materials' })
 
     expect ((await screen.findByText ('素材タグ')).closest ('a'))
-      .toHaveAttribute ('href', '/materials/8')
-    expect (screen.getByText (/画像 \/ 令和8年1月2日/)).toBeInTheDocument ()
+      .toHaveAttribute ('href', '/ja/materials/8')
+    expect (screen.getByText ('令和8年1月2日(金) 12:04:05').parentElement)
+	.toHaveTextContent ('画像 / 令和8年1月2日')
   })
 
   it ('submits list filters as material index params', async () => {
@@ -93,7 +94,7 @@ describe ('MaterialListPage', () => {
     expect (await screen.findByRole (
         'link',
         { name: '素材検索トップへ戻る' },
-    )).toHaveAttribute ('href', '/materials?material_filter=any')
+    )).toHaveAttribute ('href', '/ja/materials?material_filter=any')
   })
 
   it ('uses list view for detailed material rows', async () => {
@@ -113,7 +114,7 @@ describe ('MaterialListPage', () => {
 
     expect (await screen.findByRole ('link', { name: '詳細素材' })).toHaveAttribute (
         'href',
-        '/materials/9',
+        '/ja/materials/9',
     )
     expect (screen.getByText ('サイズ:')).toBeInTheDocument ()
     expect (screen.getByText ('2.0 KB')).toBeInTheDocument ()
@@ -153,11 +154,11 @@ describe ('MaterialListPage', () => {
 
     expect (screen.getByRole ('link', { name: '泣き' })).toHaveAttribute (
         'href',
-        '/materials?tag_id=30&include_descendants=1&group_by=parent_tag&material_filter=present',
-    )
+	'/ja/materials?tag_id=30&include_descendants=1'
+	+ '&group_by=parent_tag&material_filter=present')
     expect (screen.getByRole ('link', { name: 'タグ選択を解除' })).toHaveAttribute (
         'href',
-        '/materials?material_filter=present',
+        '/ja/materials?material_filter=present',
     )
   })
 
@@ -174,7 +175,7 @@ describe ('MaterialListPage', () => {
     expect (await screen.findByText ('選択中タグが見つかりません．')).toBeInTheDocument ()
     expect (screen.getByRole ('link', { name: 'タグ選択を解除' })).toHaveAttribute (
         'href',
-        '/materials?material_filter=present',
+        '/ja/materials?material_filter=present',
     )
   })
 })

frontend/src/pages/materials/MaterialNewPage.test.tsx

@@ -2,6 +2,7 @@ import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 import { Route, Routes, useLocation } from 'react-router-dom'
 
+import { textContentOf } from '@/test/text'
 import MaterialNewPage from '@/pages/materials/MaterialNewPage'
 import { renderWithProviders } from '@/test/render'
 
@@ -33,7 +34,7 @@ describe ('MaterialNewPage', () => {
   it ('initializes tag from query and submits form data', async () => {
     api.apiPost.mockResolvedValueOnce ({})
 
-    renderWithProviders (<MaterialNewPage/>, { route: '/materials/new?tag=%E8%99%B9%E5%A4%8F' })
+    renderWithProviders (<MaterialNewPage/>, { route: '/ja/materials/new?tag=%E8%99%B9%E5%A4%8F' })
 
     expect (screen.getAllByRole ('textbox')[0]).toHaveValue ('虹夏')
     fireEvent.change (screen.getAllByRole ('textbox')[1], {
@@ -42,12 +43,14 @@ describe ('MaterialNewPage', () => {
     fireEvent.click (screen.getByRole ('button', { name: '追加' }))
 
     await waitFor (() => {
-      expect (api.apiPost).toHaveBeenCalledWith ('/materials', expect.any (FormData))
+      expect (api.apiPost).toHaveBeenCalledWith (
+	  '/materials', expect.any (FormData), { locale: 'ja' })
     })
     const formData = api.apiPost.mock.calls[0]?.[1] as FormData
     expect (formData.get ('tag')).toBe ('虹夏')
     expect (formData.get ('url')).toBe ('https://example.com/ref')
-    expect (toastApi.toast).toHaveBeenCalledWith ({ title: '送信成功!' })
+    expect (toastApi.toast).toHaveBeenCalledTimes (1)
+    expect (textContentOf (toastApi.toast.mock.calls[0][0].title)).toBe ('送信成功!')
   })
 
   it ('shows validation errors for file and url fields', async () => {
@@ -81,12 +84,12 @@ describe ('MaterialNewPage', () => {
 
     renderWithProviders (
         <Routes>
-          <Route path="/materials/new" element={<MaterialNewPage/>}/>
-          <Route path="/materials" element={<LocationView/>}/>
+          <Route path="/ja/materials/new" element={<MaterialNewPage/>}/>
+          <Route path="/ja/materials" element={<LocationView/>}/>
         </Routes>,
         {
           route:
-              '/materials/new?tag=%E8%99%B9%E5%A4%8F'
+              '/ja/materials/new?tag=%E8%99%B9%E5%A4%8F'
               + '&return_to=%2Fmaterials%3Ftag_id%3D20',
         },
     )
@@ -96,7 +99,7 @@ describe ('MaterialNewPage', () => {
     })
     fireEvent.click (screen.getByRole ('button', { name: '追加' }))
 
-    expect (await screen.findByText ('/materials?tag_id=20')).toBeInTheDocument ()
+    expect (await screen.findByText ('/ja/materials?tag_id=20')).toBeInTheDocument ()
   })
 
   it ('ignores unsafe return_to values after successful creation', async () => {
@@ -104,12 +107,12 @@ describe ('MaterialNewPage', () => {
 
     renderWithProviders (
         <Routes>
-          <Route path="/materials/new" element={<MaterialNewPage/>}/>
-          <Route path="/materials" element={<LocationView/>}/>
+          <Route path="/ja/materials/new" element={<MaterialNewPage/>}/>
+          <Route path="/ja/materials" element={<LocationView/>}/>
         </Routes>,
         {
           route:
-              '/materials/new?tag=%E8%99%B9%E5%A4%8F'
+              '/ja/materials/new?tag=%E8%99%B9%E5%A4%8F'
               + '&return_to=https%3A%2F%2Fexample.com%2Fevil',
         },
     )
@@ -119,6 +122,6 @@ describe ('MaterialNewPage', () => {
     })
     fireEvent.click (screen.getByRole ('button', { name: '追加' }))
 
-    expect (await screen.findByText ('/materials')).toBeInTheDocument ()
+    expect (await screen.findByText ('/ja/materials')).toBeInTheDocument ()
   })
 })

frontend/src/pages/posts/PostDetailPage.test.tsx

@@ -63,7 +63,7 @@ describe ('PostDetailPage', () => {
     renderPage ()
 
     await waitFor (() => {
-      expect (postsApi.fetchPost).toHaveBeenCalledWith ('9')
+      expect (postsApi.fetchPost).toHaveBeenCalledWith ('9', 'ja')
     })
     expect (await screen.findByText ('Embed:https://example.com/9')).toBeInTheDocument ()
     expect (screen.getByRole ('button', { name: '未閲覧' })).toBeInTheDocument ()

frontend/src/pages/posts/PostHistoryPage.test.tsx

@@ -47,10 +47,10 @@ describe ('PostHistoryPage', () => {
         externalTag: '7',
         page:        1,
         limit:       20,
-      })
+      }, 'ja')
     })
 
-    expect (tagsApi.fetchExternalTag).toHaveBeenCalledWith ('7')
+    expect (tagsApi.fetchExternalTag).toHaveBeenCalledWith ('7', 'ja')
     expect (tagsApi.fetchTag).not.toHaveBeenCalled ()
 
     expect (

frontend/src/pages/posts/PostImportReviewPage.test.tsx

@@ -130,7 +130,9 @@ describe ('PostImportReviewPage', () => {
 
     renderReviewPage (['https://example.com/post'])
 
-    fireEvent.click (await screen.findByRole ('button', { name: '追加' }))
+    const submit = await screen.findByRole ('button', { name: '追加' })
+    await waitFor (() => expect (submit).toBeEnabled ())
+    fireEvent.click (submit)
 
     expect (await screen.findAllByText ('登録失敗')).toHaveLength (2)
     expect (screen.getAllByText ('invalid title')).toHaveLength (2)
@@ -147,11 +149,14 @@ describe ('PostImportReviewPage', () => {
 
     renderReviewPage (['https://example.com/post'])
 
-    fireEvent.click (await screen.findByRole ('button', { name: '追加' }))
+    const submit = await screen.findByRole ('button', { name: '追加' })
+    await waitFor (() => expect (submit).toBeEnabled ())
+    fireEvent.click (submit)
 
     await waitFor (() => {
-      expect (screen.getByLabelText ('current-location')).toHaveTextContent ('/posts')
+      expect (screen.getByLabelText ('current-location').textContent).toBe ('/ja/posts')
     })
-    expect (api.apiPost).toHaveBeenCalledWith ('/posts/bulk', expect.any (FormData))
+    expect (api.apiPost).toHaveBeenCalledWith (
+	'/posts/bulk', expect.any (FormData), { locale: 'ja' })
   })
 })

frontend/src/pages/posts/PostImportSourcePage.test.tsx

@@ -36,7 +36,8 @@ describe ('PostImportSourcePage', () => {
       target: { value: '\nftp://example.com/file\nhttps://example.com/valid' } })
     fireEvent.click (screen.getByRole ('button', { name: '次へ' }))
 
-    expect (screen.getByText (/2 行目: HTTP または HTTPS/)).toBeInTheDocument ()
+    expect (screen.getByText ('ftp://example.com/file').closest ('li'))
+	.toHaveTextContent ('2 行目: HTTP または HTTPS')
     expect (screen.getByText ('ftp://example.com/file')).toBeInTheDocument ()
     expect (input).toHaveAttribute ('aria-invalid', 'true')
     expect (router.navigate).not.toHaveBeenCalled ()
@@ -51,8 +52,8 @@ describe ('PostImportSourcePage', () => {
     fireEvent.click (screen.getByRole ('button', { name: '次へ' }))
 
     expect (router.navigate).toHaveBeenCalledWith (
-	'/posts/new?urls=https%3A%2F%2Fexample.com%2Fone%2Ba'
-	+ '+https%3A%2F%2Fexample.com%2Ftwo%3Fvalue%3Db%2Bc')
+	'/ja/posts/new?urls=https%3A%2F%2Fexample.com%2Fone%2Ba'
+	+ '+https%3A%2F%2Fexample.com%2Ftwo%3Fvalue%3Db%2Bc', undefined)
   })
 
   it ('disables Next when the encoded request target reaches 4096 bytes', () => {

frontend/src/pages/posts/PostListPage.test.tsx

@@ -43,12 +43,12 @@ describe ('PostListPage', () => {
             page:  2,
             limit: 20,
             order: 'original_created_at:desc',
-          }),
+          }), 'ja',
       )
     })
     expect (await screen.findByRole ('link', { name: '投稿5' })).toHaveAttribute (
         'href',
-        '/posts/5',
+        '/ja/posts/5',
     )
     expect (screen.getByText ('広場')).toBeInTheDocument ()
   })
@@ -75,7 +75,7 @@ describe ('PostListPage', () => {
     expect (await screen.findByText ('Wiki body')).toBeInTheDocument ()
     expect (screen.getByRole ('link', { name: 'Wiki を見る' })).toHaveAttribute (
         'href',
-        '/wiki/%E8%99%B9%E5%A4%8F',
+        '/ja/wiki/%E8%99%B9%E5%A4%8F',
     )
   })
 
@@ -92,7 +92,7 @@ describe ('PostListPage', () => {
           expect.objectContaining ({
             limit: 50,
             order: 'original_created_at:desc',
-          }),
+          }), 'ja',
       )
     })
   })
@@ -106,7 +106,7 @@ describe ('PostListPage', () => {
 
     await waitFor (() => {
       expect (postsApi.fetchPosts).toHaveBeenLastCalledWith (
-          expect.objectContaining ({ page: 1, limit: 100 }),
+          expect.objectContaining ({ page: 1, limit: 100 }), 'ja',
       )
     })
   })

frontend/src/pages/posts/PostSearchPage.test.tsx

@@ -43,12 +43,12 @@ describe ('PostSearchPage', () => {
             match: 'any',
             page:  2,
             limit: 20,
-          }),
+          }), 'ja',
       )
     })
     expect ((await screen.findAllByRole ('link', { name: '検索対象' }))[0]).toHaveAttribute (
         'href',
-        '/posts/4',
+        '/ja/posts/4',
     )
   })
 
@@ -72,7 +72,7 @@ describe ('PostSearchPage', () => {
             tags:  'tag',
             match: 'any',
             page:  1,
-          }),
+          }), 'ja',
       )
     })
   })
@@ -98,7 +98,7 @@ describe ('PostSearchPage', () => {
 
     await waitFor (() => {
       expect (postsApi.fetchPosts).toHaveBeenCalledWith (
-          expect.objectContaining ({ limit: 50, order: 'created_at:desc' }),
+          expect.objectContaining ({ limit: 50, order: 'created_at:desc' }), 'ja',
       )
     })
     expect (JSON.parse (localStorage.getItem (CLIENT_SETTINGS_STORAGE_KEY) ?? '{}'))
@@ -117,7 +117,7 @@ describe ('PostSearchPage', () => {
 
     await waitFor (() => {
       expect (postsApi.fetchPosts).toHaveBeenLastCalledWith (
-          expect.objectContaining ({ page: 1, limit: 100 }),
+          expect.objectContaining ({ page: 1, limit: 100 }), 'ja',
       )
     })
   })

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

@@ -5,6 +5,7 @@ import NicoTagListPage from '@/pages/tags/NicoTagListPage'
 import { dateString } from '@/lib/utils'
 import { buildTag, buildUser } from '@/test/factories'
 import { renderWithProviders } from '@/test/render'
+import { textContentOf } from '@/test/text'
 
 import type { NicoTag } from '@/types'
 
@@ -26,10 +27,10 @@ const scrollIntoView = vi.fn ()
 
 vi.mock ('@/lib/api', () => api)
 vi.mock ('@/components/ui/use-toast', () => toastApi)
-vi.mock ('@/components/dialogues/DialogueProvider', async importOriginal => ({
+vi.mock ('@/lib/dialogues/useDialogue', async importOriginal => ({
   ...await importOriginal<
-      typeof import('@/components/dialogues/DialogueProvider')> (),
-  useDialogue: () => dialogue }))
+      typeof import('@/lib/dialogues/useDialogue')> (),
+  default: () => dialogue }))
 
 const buildNicoTag = (values: Partial<NicoTag> = {}): NicoTag => ({
     ...buildTag (),
@@ -74,7 +75,7 @@ describe ('NicoTagListPage', () => {
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenCalledWith (
           '/tags/nico',
-          { params: {
+          { locale: 'ja', params: {
             page:        2,
             limit:       20,
             name:        'linked',
@@ -106,7 +107,7 @@ describe ('NicoTagListPage', () => {
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenLastCalledWith (
           '/tags/nico',
-          { params: {
+          { locale: 'ja', params: {
             page:        1,
             limit:       20,
             name:        'linked',
@@ -151,7 +152,7 @@ describe ('NicoTagListPage', () => {
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenLastCalledWith (
           '/tags/nico',
-          { params: expect.objectContaining ({
+          { locale: 'ja', params: expect.objectContaining ({
             page:        1,
             name:        'source',
             linked_tag:  'destination',
@@ -191,7 +192,7 @@ describe ('NicoTagListPage', () => {
       expect (api.apiPut).toHaveBeenCalledWith (
           '/tags/nico/7',
           expect.any (FormData),
-          { headers: { 'Content-Type': 'multipart/form-data' } },
+          { locale: 'ja', headers: { 'Content-Type': 'multipart/form-data' } },
       )
     })
     expect (await screen.findByText ('1 件')).toBeInTheDocument ()
@@ -217,11 +218,11 @@ describe ('NicoTagListPage', () => {
     fireEvent.click (screen.getAllByRole ('button', { name: '編集' })[0])
 
     await waitFor (() => {
-      expect (dialogue.confirm).toHaveBeenCalledWith ({
-        title:       '編集中の内容を破棄しますか?',
-        confirmText: '破棄',
-        variant:     'danger',
-      })
+      expect (dialogue.confirm).toHaveBeenCalledTimes (1)
+      const options = dialogue.confirm.mock.calls[0][0]
+      expect (textContentOf (options.title)).toBe ('編集中の内容を破棄しますか?')
+      expect (textContentOf (options.confirmText)).toBe ('破棄')
+      expect (options.variant).toBe ('danger')
     })
     expect (screen.getAllByLabelText ('連携する広場タグ')).toHaveLength (1)
     expect (screen.getByLabelText ('連携する広場タグ')).toHaveValue ('入力中')

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

@@ -2,6 +2,7 @@ import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { Route, Routes } from 'react-router-dom'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
+import { textContentOf } from '@/test/text'
 import TagDetailPage from '@/pages/tags/TagDetailPage'
 import { buildTag } from '@/test/factories'
 import { renderWithProviders } from '@/test/render'
@@ -60,11 +61,12 @@ describe ('TagDetailPage', () => {
     fireEvent.submit (screen.getByRole ('button', { name: '更新' }).closest ('form')!)
 
     await waitFor (() => {
-      expect (api.apiPut).toHaveBeenCalledWith ('/tags/7', expect.any (FormData))
+      expect (api.apiPut).toHaveBeenCalledWith ('/tags/7', expect.any (FormData), { locale: 'ja' })
     })
     const formData = api.apiPut.mock.calls[0]?.[1] as FormData
     expect (formData.get ('name')).toBe ('new')
-    expect (toastApi.toast).toHaveBeenCalledWith ({ description: '更新しました．' })
+    expect (toastApi.toast).toHaveBeenCalledTimes (1)
+    expect (textContentOf (toastApi.toast.mock.calls[0][0].description)).toBe ('更新しました．')
   })
 
   it ('keeps nico tags disabled', async () => {
@@ -77,7 +79,7 @@ describe ('TagDetailPage', () => {
 
   it ('shows validation errors returned for tag fields', async () => {
     tagsApi.fetchTag.mockResolvedValueOnce (buildTag ({ id: 7, name: 'old' }))
-    api.isApiError.mockReturnValue (true)
+    api.isApiError.mockImplementation (error => error?.response != null)
     api.apiPut.mockRejectedValueOnce ({
       response: {
         status: 422,

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

@@ -48,12 +48,12 @@ describe ('TagListPage', () => {
             order:        'post_count:desc',
             postCountGTE: 5,
             deprecated:   true,
-          }),
+          }), 'ja',
       )
     })
     expect (await screen.findByRole ('link', { name: '虹夏' })).toHaveAttribute (
         'href',
-        '/tags/7',
+        '/ja/tags/7',
     )
     expect (screen.getAllByText ('キャラクター').length).toBeGreaterThan (0)
     expect (screen.getAllByRole ('combobox')[2]).toHaveValue ('1')
@@ -77,7 +77,7 @@ describe ('TagListPage', () => {
             name:     '虹夏',
             category: 'character',
             page:     1,
-          }),
+          }), 'ja',
       )
     })
     expect (screen.getByRole ('textbox')).toHaveValue ('虹夏')
@@ -104,7 +104,7 @@ describe ('TagListPage', () => {
 
     await waitFor (() => {
       expect (tagsApi.fetchTags).toHaveBeenCalledWith (
-          expect.objectContaining ({ limit: 50, order: 'updated_at:desc' }),
+          expect.objectContaining ({ limit: 50, order: 'updated_at:desc' }), 'ja',
       )
     })
     expect (JSON.parse (localStorage.getItem (CLIENT_SETTINGS_STORAGE_KEY) ?? '{}'))
@@ -123,7 +123,7 @@ describe ('TagListPage', () => {
 
     await waitFor (() => {
       expect (tagsApi.fetchTags).toHaveBeenLastCalledWith (
-          expect.objectContaining ({ page: 1, limit: 100 }),
+          expect.objectContaining ({ page: 1, limit: 100 }), 'ja',
       )
     })
   })
@@ -152,10 +152,10 @@ describe ('TagListPage', () => {
     const externalLink =
 	screen.getByRole ('link', { name: 'nico:external_collision' })
 
-    expect (internalLink).toHaveAttribute ('href', '/tags/7')
+    expect (internalLink).toHaveAttribute ('href', '/ja/tags/7')
     expect (externalLink).toHaveAttribute (
 	'href',
-	'/tags/nico?name=nico%3Aexternal_collision',
+	'/ja/tags/nico?name=nico%3Aexternal_collision',
     )
 
     const internalRow = internalLink.closest ('tr')
@@ -166,10 +166,10 @@ describe ('TagListPage', () => {
 
     expect (
 	within (internalRow!).getByRole ('link', { name: '耕作履歴' }),
-    ).toHaveAttribute ('href', '/posts/changes?tag=7')
+    ).toHaveAttribute ('href', '/ja/posts/changes?tag=7')
 
     expect (
 	within (externalRow!).getByRole ('link', { name: '耕作履歴' }),
-    ).toHaveAttribute ('href', '/posts/changes?external_tag=7')
+    ).toHaveAttribute ('href', '/ja/posts/changes?external_tag=7')
   })
 })

frontend/src/pages/theatres/TheatreDetailPage.test.tsx

@@ -1,8 +1,10 @@
 import { act, fireEvent, screen, waitFor, within } from '@testing-library/react'
+import { QueryClient } from '@tanstack/react-query'
 import { Route, Routes } from 'react-router-dom'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import TheatreDetailPage from '@/pages/theatres/TheatreDetailPage'
+import { theatresKeys } from '@/lib/queryKeys'
 import { buildPost,
 	 buildTag,
 	 buildTheatre,
@@ -40,10 +42,10 @@ const postEmbed = vi.hoisted (() => ({
 
 vi.mock ('@/lib/api', () => api)
 vi.mock ('@/lib/posts', () => postsApi)
-vi.mock ('@/components/dialogues/DialogueProvider', async importOriginal => ({
+vi.mock ('@/lib/dialogues/useDialogue', async importOriginal => ({
   ...await importOriginal<
-      typeof import('@/components/dialogues/DialogueProvider')> (),
-  useDialogue: () => dialogue }))
+      typeof import('@/lib/dialogues/useDialogue')> (),
+  default: () => dialogue }))
 vi.mock ('@/components/PostEmbed', () => ({
   default: (props: {
     ref?: { current: unknown }
@@ -94,19 +96,28 @@ const watchingUsers = [
   { id: 2, name: 'another' },
 ]
 
-const renderPage = (user = buildUser ({ id: 1, role: 'member' })) =>
-  renderWithProviders (
+const renderPage = (
+    user = buildUser ({ id: 1, role: 'member' }),
+    prefetched = true,
+) => {
+  const queryClient = new QueryClient ({
+      defaultOptions: { queries: { retry: false, staleTime: Infinity } } })
+  if (prefetched)
+  {
+    queryClient.setQueryData (theatresKeys.show ('7', 'ja'), theatre)
+    queryClient.setQueryData (theatresKeys.programmes ('7', 'ja'), [programme])
+  }
+  return renderWithProviders (
       <Routes>
         <Route path="/theatres/:id" element={<TheatreDetailPage user={user}/>}/>
       </Routes>,
-      { route: '/theatres/7' },
-  )
+      { route: '/theatres/7', queryClient })
+}
 
 const tagSection = (): HTMLElement =>
   screen.getAllByRole ('heading', { name: 'タグ' })[0].closest ('section')!
 
 const mockDefaultApi = () => {
-  let commentsFetched = false
   let currentTheatreInfo = buildTheatreInfo ({
     postId:        currentPost.id,
     postStartedAt: '2026-01-02T03:04:05.000Z',
@@ -120,17 +131,16 @@ const mockDefaultApi = () => {
     },
   })
 
-  api.apiGet.mockImplementation ((path: string) => {
+  api.apiGet.mockImplementation ((path: string, options?: { params?: { no_gt?: number } }) => {
     switch (path)
     {
     case '/theatres/7':
       return Promise.resolve (theatre)
 
     case '/theatres/7/comments':
-      if (commentsFetched)
+      if ((options?.params?.no_gt ?? 0) >= 2)
 	return Promise.resolve ([])
 
-      commentsFetched = true
       return Promise.resolve ([
 	  buildTheatreComment ({
 	    theatreId: 7,
@@ -192,30 +202,32 @@ describe ('TheatreDetailPage', () => {
   })
 
   it ('loads theatre state, comments, current post, programme history, and weights', async () => {
-    renderPage ()
+    renderPage (undefined, false)
 
     expect (await screen.findByText ('上映会場『上映室』')).toBeInTheDocument ()
-    expect (await screen.findByText ('Embed:上映中の投稿')).toBeInTheDocument ()
-    expect (screen.getAllByText ('視聴コメント')[0]).toBeInTheDocument ()
+    expect (await screen.findByText ('Embed:上映中の投稿', {}, { timeout: 4_000 })).toBeInTheDocument ()
+    expect ((await screen.findAllByText ('視聴コメント', {}, { timeout: 4_000 }))[0])
+	.toBeInTheDocument ()
     expect (screen.getAllByText ('上映中の投稿')[0]).toBeInTheDocument ()
     expect (screen.getByText ('penalty 2')).toBeInTheDocument ()
 
     await waitFor (() => {
-      expect (postsApi.fetchPost).toHaveBeenCalledWith ('10')
+      expect (postsApi.fetchPost).toHaveBeenCalledWith ('10', 'ja')
     })
   })
 
   it ('votes to skip the current post', async () => {
     renderPage ()
 
-    await screen.findByText ('Embed:上映中の投稿')
+    await screen.findByText ('Embed:上映中の投稿', {}, { timeout: 4_000 })
 
-    fireEvent.click (screen.getByRole ('button', { name: 'スキップ 0 / 2' }))
+    fireEvent.click (await screen.findByRole ('button',
+	{ name: 'スキップ 0 / 2' }, { timeout: 4_000 }))
 
     await waitFor (() => {
       expect (api.apiPut).toHaveBeenCalledWith (
           '/theatres/7/skip_vote',
-          { post_id: 10 },
+          { post_id: 10 }, { locale: 'ja' },
       )
     })
     expect (await screen.findByRole ('button', { name: 'スキップ取消 1 / 2' }))
@@ -247,7 +259,7 @@ describe ('TheatreDetailPage', () => {
     })
 
     renderPage ()
-    await screen.findByText ('Embed:上映中の投稿')
+    await screen.findByText ('Embed:上映中の投稿', {}, { timeout: 4_000 })
 
     const props = postEmbed.props.mock.calls.at (-1)![0]
 
@@ -256,6 +268,7 @@ describe ('TheatreDetailPage', () => {
       props.onPlaybackChange (0)
     })
 
+    await waitFor (() => expect (postEmbed.seek).toHaveBeenCalled ())
     const seekMs = postEmbed.seek.mock.calls[0][0]
     expect (seekMs).toBeGreaterThanOrEqual (7_000)
     expect (seekMs).toBeLessThan (10_000)
@@ -279,14 +292,14 @@ describe ('TheatreDetailPage', () => {
       children: [childTag],
     })
 
-    postsApi.fetchPost.mockResolvedValueOnce (buildPost ({
+    postsApi.fetchPost.mockResolvedValue (buildPost ({
       ...currentPost,
       tags: [parentTag, duplicateParentTag],
     }))
 
     renderPage ()
 
-    await screen.findByText ('Embed:上映中の投稿')
+    await screen.findByText ('Embed:上映中の投稿', {}, { timeout: 4_000 })
 
     expect (within (tagSection ()).getByRole ('link', { name: '親タグ' }))
       .toBeInTheDocument ()
@@ -337,9 +350,9 @@ describe ('TheatreDetailPage', () => {
 
     renderPage ()
 
-    await screen.findByText ('Embed:上映中の投稿')
+    await screen.findByText ('Embed:上映中の投稿', {}, { timeout: 4_000 })
     await waitFor (() => {
-      expect (api.apiPut).toHaveBeenCalledWith ('/theatres/7/watching')
+      expect (api.apiPut).toHaveBeenCalledWith ('/theatres/7/watching', {}, { locale: 'ja' })
     })
 
     await waitFor (() => {
@@ -351,13 +364,16 @@ describe ('TheatreDetailPage', () => {
   it ('deletes an owned comment after confirmation', async () => {
     renderPage ()
 
-    fireEvent.click ((await screen.findAllByLabelText ('コメントを削除'))[0])
+    await screen.findByRole ('button', { name: 'スキップ 0 / 2' }, { timeout: 4_000 })
+
+    fireEvent.click ((await screen.findAllByLabelText (
+	'コメントを削除', {}, { timeout: 4_000 }))[0])
 
     await waitFor (() => {
       expect (dialogue.confirm).toHaveBeenCalled ()
     })
     await waitFor (() => {
-      expect (api.apiDelete).toHaveBeenCalledWith ('/theatres/7/comments/2')
+      expect (api.apiDelete).toHaveBeenCalledWith ('/theatres/7/comments/2', { locale: 'ja' })
     })
     expect (await screen.findAllByText ('削除されました．')).toHaveLength (2)
   })

frontend/src/pages/users/SettingPage.test.tsx

@@ -1,6 +1,7 @@
 import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
+import { textContentOf } from '@/test/text'
 import SettingPage from '@/pages/users/SettingPage'
 import { buildUser } from '@/test/factories'
 import { renderWithProviders } from '@/test/render'
@@ -68,7 +69,8 @@ describe ('SettingPage', () => {
     const formData = api.apiPut.mock.calls[0]?.[1] as FormData
     expect (formData.get ('name')).toBe ('new')
     expect (setUser).toHaveBeenCalled ()
-    expect (toastApi.toast).toHaveBeenCalledWith ({ title: '表示名を更新しました．' })
+    expect (toastApi.toast).toHaveBeenCalledTimes (1)
+    expect (textContentOf (toastApi.toast.mock.calls[0][0].title)).toBe ('表示名を更新しました．')
   })
 
   it ('shows validation errors returned for the name field', async () => {

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

@@ -24,7 +24,13 @@ const postsApi = vi.hoisted (() => ({
   fetchPosts: vi.fn (),
 }))
 
-vi.mock ('@/lib/wiki', () => wikiApi)
+vi.mock ('@/lib/wiki', () => ({
+    ...wikiApi,
+    fetchWikiAutolinkCandidates: async () => [],
+    fetchWikiPageByReference: (reference: string, ...args: unknown[]) =>
+	/^\d+$/.test (reference)
+	? wikiApi.fetchWikiPage (reference, ...args)
+	: wikiApi.fetchWikiPageByTitle (reference, ...args) }))
 vi.mock ('@/lib/tags', () => tagsApi)
 vi.mock ('@/lib/posts', () => postsApi)
 vi.mock ('@/lib/help', () => ({ getHelpTitleIndex: vi.fn () }))
@@ -63,15 +69,15 @@ describe ('WikiDetailPage', () => {
     vi.mocked (getHelpTitleIndex).mockReturnValueOnce (pending)
     tagsApi.fetchTagByName.mockResolvedValue (buildTag ({ name: '既存タグ', hasWiki: false }))
     renderWithProviders (
-	<Routes><Route path="/wiki/:title" element={<WikiDetailPage/>}/></Routes>,
-	{ route: `/wiki/${ encodeURIComponent ('既存タグ') }` })
+	<Routes><Route path="/ja/wiki/:title" element={<WikiDetailPage/>}/></Routes>,
+	{ route: `/ja/wiki/${ encodeURIComponent ('既存タグ') }` })
     await waitFor (() => expect (getHelpTitleIndex).toHaveBeenCalled ())
     expect (screen.queryByText ('404')).not.toBeInTheDocument ()
     expect (screen.queryByRole ('link', { name: '新規作成してください' }))
 	.not.toBeInTheDocument ()
     await act (async () => finish ({ }))
     expect (await screen.findByRole ('link', { name: '新規作成してください' }))
-	.toHaveAttribute ('href', `/wiki/new?title=${ encodeURIComponent ('既存タグ') }`)
+	.toHaveAttribute ('href', `/ja/wiki/new?title=${ encodeURIComponent ('既存タグ') }`)
   })
 
   it ('creates a tag description through the existing form and displays its content', async () => {
@@ -79,13 +85,13 @@ describe ('WikiDetailPage', () => {
 	resourceType: 'tag_description' })
     tagsApi.fetchTagByName.mockResolvedValue (buildTag ({ name: page.title, hasWiki: false }))
     vi.mocked (apiPost).mockResolvedValueOnce (page)
-    const path = `/wiki/${ encodeURIComponent (page.title) }`
+    const path = `/ja/wiki/${ encodeURIComponent (page.title) }`
     const { container, queryClient } = renderWithProviders (
 	<>
 	  <Location/>
 	  <Routes>
-	    <Route path="/wiki/new" element={<WikiNewPage user={buildUser ({ role: 'member' })}/>}/>
-	    <Route path="/wiki/:title" element={<WikiDetailPage/>}/>
+	    <Route path="/ja/wiki/new" element={<WikiNewPage user={buildUser ({ role: 'member' })}/>}/>
+	    <Route path="/ja/wiki/:title" element={<WikiDetailPage/>}/>
 	  </Routes>
 	</>, { route: path })
     fireEvent.click (await screen.findByRole ('link', { name: '新規作成してください' }))
@@ -108,11 +114,10 @@ describe ('WikiDetailPage', () => {
     expect (form.get ('title')).toBe (page.title)
     expect (form.get ('body')).toBe (page.body)
     expect (apiPost).toHaveBeenCalledWith ('/wiki', form,
-	{ headers: { 'Content-Type': 'multipart/form-data' } })
+	{ locale: 'ja', headers: { 'Content-Type': 'multipart/form-data' } })
     expect (screen.queryByText ('404')).not.toBeInTheDocument ()
     expect (queryClient.getQueryData (wikiKeys.show (page.title, { }))).toEqual (page)
-    await waitFor (() => expect (queryClient.getQueryData (wikiKeys.index ({ })))
-	.toEqual ([page]))
+    expect (queryClient.getQueryState (wikiKeys.index ({ }))?.isInvalidated).toBe (true)
     await waitFor (() => expect (queryClient.getQueryData (tagsKeys.show (page.title)))
 	.toMatchObject ({ hasWiki: true }))
     expect (getHelpTitleIndex).toHaveBeenCalledTimes (1)
@@ -121,7 +126,7 @@ describe ('WikiDetailPage', () => {
   it ('keeps failed saves on the form without changing cached Wiki or tag state', async () => {
     const title = '既存タグ'
     const tag = buildTag ({ name: title, hasWiki: false })
-    const path = `/wiki/new?title=${ encodeURIComponent (title) }`
+    const path = `/ja/wiki/new?title=${ encodeURIComponent (title) }`
     vi.mocked (apiPost).mockRejectedValueOnce (new Error ('save failed'))
     const { queryClient } = renderWithProviders (
 	<><Location/><WikiNewPage user={buildUser ({ role: 'member' })}/></>, { route: path })
@@ -141,8 +146,8 @@ describe ('WikiDetailPage', () => {
 
   it ('shows NotFound when neither a tag nor a Help title exists', async () => {
     renderWithProviders (
-	<Routes><Route path="/wiki/:title" element={<WikiDetailPage/>}/></Routes>,
-	{ route: '/wiki/missing' })
+	<Routes><Route path="/ja/wiki/:title" element={<WikiDetailPage/>}/></Routes>,
+	{ route: '/ja/wiki/missing' })
     expect (await screen.findByText ('404')).toBeInTheDocument ()
     expect (screen.queryByRole ('link', { name: '新規作成してください' }))
 	.not.toBeInTheDocument ()
@@ -153,8 +158,8 @@ describe ('WikiDetailPage', () => {
 	wikiApi.fetchWikiPageByTitle.mockRejectedValue (new Error (message))
 	tagsApi.fetchTagByName.mockResolvedValue (buildTag ({ name: '既存タグ' }))
 	renderWithProviders (
-	    <Routes><Route path="/wiki/:title" element={<WikiDetailPage/>}/></Routes>,
-	    { route: `/wiki/${ encodeURIComponent ('既存タグ') }` })
+	    <Routes><Route path="/ja/wiki/:title" element={<WikiDetailPage/>}/></Routes>,
+	    { route: `/ja/wiki/${ encodeURIComponent ('既存タグ') }` })
 	expect (await screen.findByRole ('alert')).toHaveTextContent (message)
 	expect (getHelpTitleIndex).not.toHaveBeenCalled ()
 	expect (screen.queryByRole ('link', { name: '新規作成してください' }))
@@ -174,9 +179,9 @@ describe ('WikiDetailPage', () => {
 
     renderWithProviders (
         <Routes>
-          <Route path="/wiki/:title" element={<WikiDetailPage/>}/>
+          <Route path="/ja/wiki/:title" element={<WikiDetailPage/>}/>
         </Routes>,
-        { route: '/wiki/%E6%97%A7%E3%82%BF%E3%82%B0' },
+        { route: '/ja/wiki/%E6%97%A7%E3%82%BF%E3%82%B0' },
     )
 
     const marker = await screen.findByText ('（廃止）')

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

@@ -36,10 +36,10 @@ describe ('WikiDiffPage', () => {
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenCalledWith (
           '/wiki/3/diff',
-          { params: { from: '1', to: '2' } },
+          { locale: 'ja', params: { from: '1', to: '2' } },
       )
     })
-    expect (screen.getByText ('差分対象')).toBeInTheDocument ()
+    expect (await screen.findByText ('差分対象')).toBeInTheDocument ()
     expect (screen.getByText ('same')).toBeInTheDocument ()
     expect (screen.getByText ('added line')).toBeInTheDocument ()
     expect (screen.getByText ('removed line')).toBeInTheDocument ()

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

@@ -2,6 +2,7 @@ import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { Route, Routes } from 'react-router-dom'
 import { describe, expect, it, vi } from 'vitest'
 
+import { textContentOf } from '@/test/text'
 import WikiEditPage from '@/pages/wiki/WikiEditPage'
 import { buildUser, buildWikiPage } from '@/test/factories'
 import { renderWithProviders } from '@/test/render'
@@ -50,9 +51,9 @@ describe ('WikiEditPage', () => {
     renderPage ()
 
     await waitFor (() => {
-      expect (api.apiGet).toHaveBeenCalledWith ('/wiki/9')
+      expect (api.apiGet).toHaveBeenCalledWith ('/wiki/9', { locale: 'ja' })
     })
-    expect (screen.getAllByRole ('textbox')[0]).toHaveValue ('既存')
+    expect ((await screen.findAllByRole ('textbox'))[0]).toHaveValue ('既存')
     expect (screen.getByLabelText ('本文エディタ')).toHaveValue ('本文')
   })
 
@@ -71,12 +72,13 @@ describe ('WikiEditPage', () => {
       expect (api.apiPut).toHaveBeenCalledWith (
           '/wiki/9',
           expect.any (FormData),
-          { headers: { 'Content-Type': 'multipart/form-data' } },
+          { locale: 'ja', headers: { 'Content-Type': 'multipart/form-data' } },
       )
     })
     const formData = api.apiPut.mock.calls[0]?.[1] as FormData
     expect (formData.get ('title')).toBe ('更新済み')
     expect (formData.get ('body')).toBe ('更新本文')
-    expect (toastApi.toast).toHaveBeenCalledWith ({ title: '投稿成功!' })
+    expect (toastApi.toast).toHaveBeenCalledTimes (1)
+    expect (textContentOf (toastApi.toast.mock.calls[0][0].title)).toBe ('投稿成功!')
   })
 })

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

@@ -36,7 +36,7 @@ const renderWiki = (title: string) => {
 	<Location/>
 	<Routes>
 	  <Route path="/wiki/:title" element={<WikiDetailPage/>}/>
-	  <Route path="/help/:identifier" element={<HelpDetailPage/>}/>
+	  <Route path="/ja/help/:identifier" element={<HelpDetailPage/>}/>
 	  <Route path="/404" element={<div>unexpected redirect</div>}/>
 	</Routes>
       </>, { route })

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

@@ -32,7 +32,7 @@ describe ('WikiHistoryPage', () => {
     const link = await screen.findByRole ('link', { name: '旧タグ' })
     const marker = screen.getByText ('（廃止）')
 
-    expect (link).toHaveAttribute ('href', '/wiki/%E6%97%A7%E3%82%BF%E3%82%B0?version=2')
+    expect (link).toHaveAttribute ('href', '/ja/wiki/3?version=2')
     expect (marker.closest ('a')).toBeNull ()
   })
 })

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

@@ -1,6 +1,7 @@
 import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { describe, expect, it, vi } from 'vitest'
 
+import { textContentOf } from '@/test/text'
 import WikiNewPage from '@/pages/wiki/WikiNewPage'
 import { buildUser, buildWikiPage } from '@/test/factories'
 import { renderWithProviders } from '@/test/render'
@@ -50,12 +51,13 @@ describe ('WikiNewPage', () => {
       expect (api.apiPost).toHaveBeenCalledWith (
           '/wiki',
           expect.any (FormData),
-          { headers: { 'Content-Type': 'multipart/form-data' } },
+          { locale: 'ja', headers: { 'Content-Type': 'multipart/form-data' } },
       )
     })
     const formData = api.apiPost.mock.calls[0]?.[1] as FormData
     expect (formData.get ('title')).toBe ('下書き')
     expect (formData.get ('body')).toBe ('本文')
-    expect (toastApi.toast).toHaveBeenCalledWith ({ title: '投稿成功!' })
+    expect (toastApi.toast).toHaveBeenCalledTimes (1)
+    expect (textContentOf (toastApi.toast.mock.calls[0][0].title)).toBe ('投稿成功!')
   })
 })

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

@@ -16,8 +16,8 @@ describe ('Wiki resource identity', () => {
     vi.mocked (apiGet).mockResolvedValueOnce ([buildWikiPage ({ title: '虹夏' })])
     renderWithProviders (<WikiSearchPage/>)
     expect (await screen.findByRole ('link', { name: '虹夏' }))
-	.toHaveAttribute ('href', '/wiki/%E8%99%B9%E5%A4%8F')
-    expect (apiGet).toHaveBeenCalledWith ('/wiki', { params: { title: '' } })
+	.toHaveAttribute ('href', '/ja/wiki/%E8%99%B9%E5%A4%8F')
+    expect (apiGet).toHaveBeenCalledWith ('/wiki', { locale: 'ja', params: { title: '' } })
   })
 
   it ('searches by title on submit', async () => {
@@ -28,7 +28,7 @@ describe ('Wiki resource identity', () => {
     fireEvent.change (screen.getAllByRole ('textbox')[0], { target: { value: '検索' } })
     fireEvent.click (screen.getByRole ('button', { name: '検索' }))
     await waitFor (() => expect (apiGet).toHaveBeenLastCalledWith (
-	'/wiki', { params: { title: '検索' } }))
+	'/wiki', { locale: 'ja', params: { title: '検索' } }))
     expect (await screen.findByRole ('link', { name: '検索結果' })).toBeInTheDocument ()
   })
 
@@ -49,7 +49,7 @@ describe ('Wiki resource identity', () => {
 
     await screen.findByRole ('link', { name: '説明' })
     expect (screen.getByRole ('link', { name: 'タググループ:一覧' }))
-	.toHaveAttribute ('href', `/wiki/${ encodeURIComponent (group.title) }`)
+	.toHaveAttribute ('href', `/ja/wiki/${ encodeURIComponent (group.title) }`)
     await waitFor (() => {
       expect (errors.mock.calls.some (args => args.some (value =>
 	  String (value).includes ('same key')))).toBe (false)

frontend/src/test/compileMdx.ts

@@ -14,7 +14,7 @@ export const transformMdx = async (source: string, suffix = '.mdx') => {
   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${suffix}`)
+  return await plugin.transform.call (plugin, source, `/test/help-table${suffix}`) ?? null
 }
 
 

frontend/src/test/render.tsx

@@ -11,8 +11,8 @@ import { UnsavedChangesGuardProvider } from '@/lib/useUnsavedChangesGuard'
 import type { ReactElement, ReactNode } from 'react'
 
 type Options = {
-  route?: string
-}
+    route?: string
+    queryClient?: QueryClient }
 
 const TestContentContext = createContext<ReactNode> (null)
 
@@ -34,10 +34,8 @@ export const renderWithProviders = (
     ui:       ReactElement,
     options: Options = {},
 ) => {
-  const queryClient = new QueryClient ({
-    defaultOptions: {
-      queries: { retry: false } },
-  })
+  const queryClient = options.queryClient ?? new QueryClient ({
+      defaultOptions: { queries: { retry: false } } })
 
   const Wrapper = ({ children }: { children: ReactNode }) => {
     const [router] = useState (() => createMemoryRouter ([{

frontend/src/test/text.tsx

@@ -0,0 +1,10 @@
+import { renderToStaticMarkup } from 'react-dom/server'
+
+import type { ReactNode } from 'react'
+
+
+export const textContentOf = (node: ReactNode): string => {
+  const container = document.createElement ('div')
+  container.innerHTML = renderToStaticMarkup (<>{node}</>)
+  return container.textContent ?? ''
+}

frontend/vitest.config.ts

@@ -7,5 +7,6 @@ export default mergeConfig (
     viteConfig,
     defineConfig ({
 	test: { environment:  'jsdom',
+		exclude: ['**/node_modules/**', '**/dist/**', 'server.ssr.test.mjs'],
 		setupFiles:   './src/test/setup.ts',
 		globals:      false } }))