#399

AGENTS.md

@@ -140,10 +140,22 @@ npm run preview
   99 文字を超えるなら block 形式へ切り替へるか、message 定数化などで縮める。
 - Ruby の method chain や call argument を折り返す際、call-site の `)` を
   block close のやうに独立させない。
+- Ruby では、行末の `\` を用途を問はず一切使用しない。
+- Ruby では、文字列連結、logger message、method call、条件式、SQL 断片、
+  正規表現その他すべての式で、行末バックスラッシュによる継続を禁止する。
 - Ruby の block body は、その基準位置から 2 空白深くする。
 - Ruby の wrapped expression、method argument、array element、hash pair などの
   continuation indentation は、その statement の基準位置から 4 空白深くする。
 - Ruby の continuation indentation を、行頭からの絶対空白数として扱はない。
+- Ruby では、暗黙的に継続可能な構文を優先し、method call、array、Hash 及び
+  括弧内ではバックスラッシュなしで改行する。
+- Ruby では、行長制限を守るために行末バックスラッシュを導入してはならない。
+- Ruby で行末バックスラッシュが必要に見える場合は、括弧内で自然に改行する、
+  一つの文字列補間へまとめる、中間変数へ分ける、`format` を使ふ、heredoc を
+  使ふ、array 又は Hash を組み立ててから処理する、条件式全体を括弧で囲む、
+  method へ抽出する、のいづれかへ書き換へる。
+- formatter 又は自動修正にも、Ruby の行末バックスラッシュを生成させない。
+- 新規 code だけでなく、今回触れる Ruby code にも行末バックスラッシュを残さない。
 - 例へば class body 内の array は、class body の 2 空白を基準に、更に 4 空白
   深くするため、結果として行頭から 6 空白になる。
 
@@ -197,6 +209,48 @@ end
 
 Bad:
 
+```rb
+Rails.logger.info(
+    "post_import_metadata_fetch_failure "\
+    "#{ payload.to_json }")
+```
+
+Good:
+
+```rb
+payload = {
+    error: e.class.name,
+    message: e.message }
+
+Rails.logger.info(
+    "post_import_metadata_fetch_failure #{ payload.to_json }")
+```
+
+Bad:
+
+```rb
+message = "first "\
+          "second"
+```
+
+Good:
+
+```rb
+message = format(
+    '%<first>s %<second>s',
+    first: 'first',
+    second: 'second')
+```
+
+Bad:
+
+```rb
+result = first_value + \
+         second_value
+```
+
+Bad:
+
 ```rb
 records.each {
   do_work(_1) }

backend/app/models/post.rb

@@ -138,8 +138,10 @@ class Post < ApplicationRecord
   end
 
   def self.section_literal section
-    "[#{ Post.ms_to_time(section.begin_ms) }-"\
-    "#{ section.end_ms ? Post.ms_to_time(section.end_ms) : '' }]"
+    end_ms =
+        section.end_ms ? Post.ms_to_time(section.end_ms) : ''
+
+    "[#{ Post.ms_to_time(section.begin_ms) }-#{ end_ms }]"
   end
 
   def self.ms_to_time ms

backend/app/representations/post_repr.rb

@@ -106,11 +106,14 @@ module PostRepr
 
     Rails.application.routes.url_helpers.rails_storage_proxy_url(post.thumbnail, **options)
   rescue ActionController::UrlGenerationError, ArgumentError, URI::InvalidURIError => e
-    Rails.logger.warn(
-        "PostRepr.thumbnail_url failed post_id=#{post.id} " \
-        "attachment_id=#{post.thumbnail.attachment&.id} " \
-        "blob_id=#{post.thumbnail.blob&.id} " \
-        "error_class=#{e.class} message=#{e.message}")
+    payload = {
+        post_id: post.id,
+        attachment_id: post.thumbnail.attachment&.id,
+        blob_id: post.thumbnail.blob&.id,
+        error_class: e.class,
+        message: e.message }
+
+    Rails.logger.warn("PostRepr.thumbnail_url failed #{ payload.to_json }")
     nil
   end
 end

backend/app/services/post_import_previewer.rb

@@ -225,15 +225,15 @@ class PostImportPreviewer
     end
     { data:, warnings:, validation_errors: { } }
   rescue Preview::UrlSafety::UnsafeUrl => e
+    payload = { error: e.class.name, message: e.message }
     Rails.logger.info(
-        "post_import_metadata_fetch_unsafe_url "\
-        "#{ { error: e.class.name, message: e.message }.to_json }")
+        "post_import_metadata_fetch_unsafe_url #{ payload.to_json }")
     { data: { }, warnings: { }, validation_errors: { url: [e.message] } }
   rescue Preview::HttpFetcher::FetchFailed,
          Preview::HttpFetcher::ResponseTooLarge => e
+    payload = { error: e.class.name, message: e.message }
     Rails.logger.info(
-        "post_import_metadata_fetch_failure "\
-        "#{ { error: e.class.name, message: e.message }.to_json }")
+        "post_import_metadata_fetch_failure #{ payload.to_json }")
     { data: { }, warnings: { 'url' => [METADATA_FETCH_WARNING] }, validation_errors: { } }
   end
 
@@ -335,14 +335,14 @@ class PostImportPreviewer
   def safe_fetch_metadata url
     fetch_metadata(url)
   rescue Preview::UrlSafety::UnsafeUrl => e
+    payload = { error: e.class.name, message: e.message }
     Rails.logger.info(
-        "post_import_metadata_fetch_unsafe_url "\
-        "#{ { error: e.class.name, message: e.message }.to_json }")
+        "post_import_metadata_fetch_unsafe_url #{ payload.to_json }")
     { data: { }, warnings: { }, validation_errors: { url: [e.message] } }
   rescue StandardError => e
+    payload = { error: e.class.name, message: e.message }
     Rails.logger.error(
-        "post_import_metadata_fetch_unexpected_failure "\
-        "#{ { error: e.class.name, message: e.message }.to_json }")
+        "post_import_metadata_fetch_unexpected_failure #{ payload.to_json }")
     { data: { }, warnings: { 'url' => [METADATA_FETCH_WARNING] }, validation_errors: { } }
   end
 

backend/app/services/post_metadata_fetcher.rb

@@ -3,10 +3,9 @@ require 'date'
 
 class PostMetadataFetcher
   TIMESTAMP_PATTERN =
-      Regexp.new(
-          '\A(\d{4})-(\d{2})-(\d{2})T(\d{2})' \
-          '(?::(\d{2})(?::(\d{2})(?:\.(\d+))?)?)?' \
-          '(Z|[+-]\d{2}:?\d{2})?\z')
+      /\A(\d{4})-(\d{2})-(\d{2})T(\d{2})
+        (?::(\d{2})(?::(\d{2})(?:\.(\d+))?)?)?
+        (Z|[+-]\d{2}:?\d{2})?\z/x
 
   def self.fetch raw_url
     uri, = Preview::UrlSafety.validate(raw_url)

backend/config/environments/development.rb

@@ -1,4 +1,4 @@
-require "active_support/core_ext/integer/time"
+require 'active_support/core_ext/integer/time'
 
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
@@ -17,8 +17,8 @@ Rails.application.configure do
 
   # Enable/disable Action Controller caching. By default Action Controller caching is disabled.
   # Run rails dev:cache to toggle Action Controller caching.
-  if Rails.root.join("tmp/caching-dev.txt").exist?
-    config.public_file_server.headers = { "cache-control" => "public, max-age=#{2.days.to_i}" }
+  if Rails.root.join('tmp/caching-dev.txt').exist?
+    config.public_file_server.headers = { 'cache-control' => "public, max-age=#{2.days.to_i}" }
   else
     config.action_controller.perform_caching = false
   end

backend/spec/requests/posts_spec.rb

@@ -101,34 +101,34 @@ RSpec.describe 'Posts API', type: :request do
     end
   end
 
-  describe "GET /posts" do
+  describe 'GET /posts' do
     let!(:user) { create_member_user! }
 
-    let!(:tag_name) { TagName.create!(name: "spec_tag") }
+    let!(:tag_name) { TagName.create!(name: 'spec_tag') }
     let!(:tag) { Tag.create!(tag_name:, category: :general) }
     let!(:tag_name2) { TagName.create!(name: 'unko') }
     let!(:tag2) { Tag.create!(tag_name: tag_name2, category: :deerjikist) }
     let!(:alias_tag_name) { TagName.create!(name: 'manko', canonical: tag_name) }
 
     let!(:hit_post) do
-      Post.create!(uploaded_user: user, title: "hello spec world",
+      Post.create!(uploaded_user: user, title: 'hello spec world',
                    url: 'https://example.com/spec2').tap do |p|
         PostTag.create!(post: p, tag:)
       end
     end
 
     let!(:miss_post) do
-      Post.create!(uploaded_user: user, title: "unrelated title",
+      Post.create!(uploaded_user: user, title: 'unrelated title',
                    url: 'https://example.com/spec3').tap do |p|
         PostTag.create!(post: p, tag: tag2)
       end
     end
 
     it 'returns posts with tag name in JSON' do
-      get "/posts"
+      get '/posts'
 
       expect(response).to have_http_status(:ok)
-      posts = json.fetch("posts")
+      posts = json.fetch('posts')
 
       # 全postの全tagが name を含むこと
       expect(posts).not_to be_empty
@@ -141,8 +141,8 @@ RSpec.describe 'Posts API', type: :request do
       expect(json['count']).to be_an(Integer)
 
       # spec_tag を含む投稿が存在すること
-      all_tag_names = posts.flat_map { |p| p["tags"].map { |t| t["name"] } }
-      expect(all_tag_names).to include("spec_tag")
+      all_tag_names = posts.flat_map { |p| p['tags'].map { |t| t['name'] } }
+      expect(all_tag_names).to include('spec_tag')
     end
 
     it 'keeps children and sections keys in non-detail tag responses' do
@@ -201,10 +201,10 @@ RSpec.describe 'Posts API', type: :request do
       end
 
       it 'returns empty posts when nothing matches' do
-        get "/posts", params: { tags: "no_such_keyword_12345" }
+        get '/posts', params: { tags: 'no_such_keyword_12345' }
 
         expect(response).to have_http_status(:ok)
-        expect(json.fetch("posts")).to eq([])
+        expect(json.fetch('posts')).to eq([])
         expect(json.fetch('count')).to eq(0)
       end
     end
@@ -1712,8 +1712,10 @@ RSpec.describe 'Posts API', type: :request do
         expect(post_record.reload.title).to eq('updated by other user')
       end
 
-      it 'returns 409 with mergeable true when stale tag changes'\
-         ' do not conflict but merge is not requested' do
+      it(
+          'returns 409 with mergeable true when stale tag changes '
+          'do not conflict but merge is not requested'
+      ) do
         sign_in_as(member)
 
         base_version = create_post_version_for!(post_record.reload)

backend/spec/tasks/nico_sync_spec.rb

@@ -1,10 +1,10 @@
-require "rails_helper"
+require 'rails_helper'
 
 
-RSpec.describe "nico:sync" do
+RSpec.describe 'nico:sync' do
   def stub_python(json_array)
     status = instance_double(Process::Status, success?: true)
-    allow(Open3).to receive(:capture3).and_return([json_array.to_json, "", status])
+    allow(Open3).to receive(:capture3).and_return([json_array.to_json, '', status])
   end
 
   def create_tag!(name, category:)
@@ -25,12 +25,12 @@ RSpec.describe "nico:sync" do
     )
 
     # 既存の非nicoタグ（kept_non_nico_ids）
-    kept_general = create_tag!("spec_kept", category: "general")
+    kept_general = create_tag!('spec_kept', category: 'general')
     PostTag.create!(post: post, tag: kept_general)
 
     # 追加される linked tag を準備（nico tag に紐付く一般タグ）
-    linked = create_tag!("spec_linked", category: "general")
-    nico = create_tag!("nico:AAA", category: "nico")
+    linked = create_tag!('spec_linked', category: 'general')
+    nico = create_tag!('nico:AAA', category: 'nico')
     link_nico_to_tag!(nico, linked)
 
     # bot / tagme は task 内で使うので作っておく（Tag.bot/tagme がある前提）
@@ -46,22 +46,22 @@ RSpec.describe "nico:sync" do
         'deleted_at' => '2026-01-31 00:00:00' }])
 
     # 外部HTTPは今回「既存 post なので呼ばれない」はずだが、念のため塞ぐ
-    allow(URI).to receive(:open).and_return(StringIO.new("<html></html>"))
+    allow(URI).to receive(:open).and_return(StringIO.new('<html></html>'))
 
-    run_rake_task("nico:sync")
+    run_rake_task('nico:sync')
 
     post.reload
-    active_tag_names = post.tags.joins(:tag_name).pluck("tag_names.name")
+    active_tag_names = post.tags.joins(:tag_name).pluck('tag_names.name')
 
-    expect(active_tag_names).to include("spec_kept")
-    expect(active_tag_names).to include("nico:AAA")
-    expect(active_tag_names).to include("spec_linked")
+    expect(active_tag_names).to include('spec_kept')
+    expect(active_tag_names).to include('nico:AAA')
+    expect(active_tag_names).to include('spec_linked')
 
     expect(post.original_created_from).to eq(Time.iso8601('2026-01-01T03:34:00Z'))
     expect(post.original_created_before).to eq(Time.iso8601('2026-01-01T03:35:00Z'))
 
     # 差分が出るので bot が付く（kept_non_nico_ids != desired_non_nico_ids）
-    expect(active_tag_names).to include("bot操作")
+    expect(active_tag_names).to include('bot操作')
   end
 
   it '既存 post のサムネール取得に共通 attach 経路を使ふ' do
@@ -116,21 +116,21 @@ RSpec.describe "nico:sync" do
     )
 
     # 旧nicoタグ（今回の同期結果に含まれない）
-    old_nico = create_tag!("nico:OLD", category: "nico")
+    old_nico = create_tag!('nico:OLD', category: 'nico')
     old_pt = PostTag.create!(post: post, tag: old_nico)
     expect(old_pt.discarded_at).to be_nil
 
     # 今回は NEW のみ欲しい
-    new_nico = create_tag!("nico:NEW", category: "nico")
+    new_nico = create_tag!('nico:NEW', category: 'nico')
 
     # bot/tagme 念のため
     Tag.bot
     Tag.tagme
 
-    stub_python([{ "code" => "sm9", "title" => "t", "tags" => ["NEW"] }])
-    allow(URI).to receive(:open).and_return(StringIO.new("<html></html>"))
+    stub_python([{ 'code' => 'sm9', 'title' => 't', 'tags' => ['NEW'] }])
+    allow(URI).to receive(:open).and_return(StringIO.new('<html></html>'))
 
-    run_rake_task("nico:sync")
+    run_rake_task('nico:sync')
 
     # OLD は active から外れる（discarded_at が入る）
     old_pts = PostTag.where(post_id: post.id, tag_id: old_nico.id).order(:id).to_a
@@ -138,9 +138,9 @@ RSpec.describe "nico:sync" do
 
     # NEW は active にいる
     post.reload
-    active_names = post.tags.joins(:tag_name).pluck("tag_names.name")
-    expect(active_names).to include("nico:NEW")
-    expect(active_names).not_to include("nico:OLD")
+    active_names = post.tags.joins(:tag_name).pluck('tag_names.name')
+    expect(active_names).to include('nico:NEW')
+    expect(active_names).not_to include('nico:OLD')
   end
 
   def snapshot_tags(post)

frontend/src/pages/materials/MaterialListPage.tsx

@@ -13,7 +13,7 @@ import MainArea from '@/components/layout/MainArea'
 import { SITE_TITLE } from '@/config'
 import { fetchMaterials, parseMaterialFilter } from '@/lib/materials'
 import { materialsKeys } from '@/lib/queryKeys'
-import { dateString, inputClass } from '@/lib/utils'
+import { cn, dateString, inputClass } from '@/lib/utils'
 
 import type { FC, FormEvent } from 'react'
 
@@ -113,10 +113,11 @@ const clearedTagSelectionPath = (
 
 const MaterialThumb: FC<{ material: Material }> = ({ material }) => (
     <div
-	className={`flex aspect-square h-[180px] w-[180px] items-center justify-center
-		    overflow-hidden rounded-lg border border-stone-200 bg-white text-center
-		    text-stone-900 shadow-sm dark:border-stone-700 dark:bg-stone-900
-		    dark:text-stone-100`}>
+	className={cn (
+	    'flex aspect-square h-[180px] w-[180px] items-center justify-center',
+	    'overflow-hidden rounded-lg border border-stone-200 bg-white text-center',
+	    'text-stone-900 shadow-sm dark:border-stone-700 dark:bg-stone-900',
+	    'dark:text-stone-100')}>
       {material.thumbnail
        ? <img src={material.thumbnail} alt="" className="block h-full w-full object-cover"/>
        : (
@@ -534,27 +535,29 @@ const MaterialListPage: FC = () => {
 		      <button
 			  type="button"
 			  onClick={() => updateQuery ({ view: 'card' })}
-		  className={`rounded-full border px-4 py-2 text-sm ${
+			  className={cn (
+			      'rounded-full border px-4 py-2 text-sm',
 			      view === 'card'
 			      ? [
 				  'border-sky-500 bg-sky-50 text-sky-700 dark:border-sky-400',
-			  'dark:bg-sky-950 dark:text-sky-100'].join (' ')
+				  'dark:bg-sky-950 dark:text-sky-100']
 			      : [
 				  'border-stone-300 bg-white text-stone-900 dark:border-stone-700',
-			  'dark:bg-stone-900 dark:text-stone-100'].join (' ') }`}>
+				  'dark:bg-stone-900 dark:text-stone-100'])}>
 		アイコン
 	      </button>
 		      <button
 			  type="button"
 			  onClick={() => updateQuery ({ view: 'list' })}
-		  className={`rounded-full border px-4 py-2 text-sm ${
+			  className={cn (
+			      'rounded-full border px-4 py-2 text-sm',
 			      view === 'list'
 			      ? [
 				  'border-sky-500 bg-sky-50 text-sky-700 dark:border-sky-400',
-			  'dark:bg-sky-950 dark:text-sky-100'].join (' ')
+				  'dark:bg-sky-950 dark:text-sky-100']
 			      : [
 				  'border-stone-300 bg-white text-stone-900 dark:border-stone-700',
-			  'dark:bg-stone-900 dark:text-stone-100'].join (' ') }`}>
+				  'dark:bg-stone-900 dark:text-stone-100'])}>
 		詳細
 	      </button>
 	    </div>