#90

backend/app/controllers/application_controller.rb

@@ -1,4 +1,7 @@
 class ApplicationController < ActionController::API
+  rescue_from ActiveRecord::RecordInvalid, with: :render_record_invalid
+  rescue_from ActiveRecord::RecordNotUnique, with: :render_record_not_unique
+
   before_action :reject_banned_ip_address!
   before_action :authenticate_user
   before_action :reject_banned_user!
@@ -25,6 +28,29 @@ class ApplicationController < ActionController::API
     end
   end
 
+  def render_bad_request message = 'リクエストが不正です．', field: nil, code: :bad_request
+    render_error(:bad_request, message, field:, code:)
+  end
+
+  def render_unprocessable_entity message = '入力を確認してください．', field: nil, code: :invalid
+    render_error(:unprocessable_entity, message, field:, code:)
+  end
+
+  def render_error status, message, field: nil, code: status
+    error = { code: code.to_s, message: }
+    error[:field] = field.to_s if field.present?
+
+    render json: { errors: [error] }, status:
+  end
+
+  def render_record_invalid error
+    render_validation_error error.record
+  end
+
+  def render_record_not_unique _error = nil
+    render_validation_error base: ['すでに存在してゐます．']
+  end
+
   def reject_banned_ip_address!
     ip_address = IpAddress.find_by(ip_address: IPAddr.new(request.remote_ip).hton)
     return unless ip_address&.banned?
@@ -37,4 +63,28 @@ class ApplicationController < ActionController::API
 
     head :forbidden
   end
+
+  def render_validation_error record = nil, fields: { }, base: [], status: :unprocessable_entity
+    errors = { }
+
+    if record
+      record.errors.each do |error|
+        errors[error.attribute] ||= []
+        errors[error.attribute] << error.message
+      end
+    end
+
+    fields.each do |attr, messages|
+      errors[attr.to_sym] ||= []
+      errors[attr.to_sym].concat(Array(messages))
+    end
+
+    base_errors = Array(base) + Array(errors.delete(:base))
+
+    render json: { type: 'validation_error',
+                   message: '入力内容を確認してください．',
+                   errors:,
+                   base_errors: },
+           status:
+  end
 end

backend/app/controllers/deerjikists_controller.rb

@@ -2,7 +2,8 @@ class DeerjikistsController < ApplicationController
   def show
     platform = params[:platform].to_s.strip
     code = params[:code].to_s.strip
-    return head :bad_request if platform.blank? || code.blank?
+    return render_bad_request('platform は必須です．', field: :platform) if platform.blank?
+    return render_bad_request('code は必須です．', field: :code) if code.blank?
 
     deerjikist = Deerjikist
                  .joins(:tag)
@@ -22,7 +23,9 @@ class DeerjikistsController < ApplicationController
     platform = params[:platform].to_s.strip
     code = params[:code].to_s.strip
     tag_id = params[:tag_id].to_i
-    return head :bad_request if platform.blank? || code.blank? || tag_id <= 0
+    return render_bad_request('platform は必須です．', field: :platform) if platform.blank?
+    return render_bad_request('code は必須です．', field: :code) if code.blank?
+    return render_bad_request('tag_id が不正です．', field: :tag_id) if tag_id <= 0
 
     deerjikist = Deerjikist.find_or_initialize_by(platform:, code:).tap do |d|
       d.tag_id = tag_id
@@ -38,7 +41,8 @@ class DeerjikistsController < ApplicationController
 
     platform = params[:platform].to_s.strip
     code = params[:code].to_s.strip
-    return head :bad_request if platform.blank? || code.blank?
+    return render_bad_request('platform は必須です．', field: :platform) if platform.blank?
+    return render_bad_request('code は必須です．', field: :code) if code.blank?
 
     Deerjikist.find([platform, code]).destroy!
 

backend/app/controllers/materials_controller.rb

@@ -40,7 +40,8 @@ class MaterialsController < ApplicationController
     tag_name_raw = params[:tag].to_s.strip
     file = params[:file]
     url = params[:url].to_s.strip.presence
-    return head :bad_request if tag_name_raw.blank? || (file.blank? && url.blank?)
+    return render_bad_request('タグは必須です．', field: :tag) if tag_name_raw.blank?
+    return render_bad_request('ファイルまたは URL は必須です．') if file.blank? && url.blank?
 
     tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
     tag = tag_name.tag
@@ -54,7 +55,7 @@ class MaterialsController < ApplicationController
     if material.save
       render json: MaterialRepr.base(material, host: request.base_url), status: :created
     else
-      render json: { errors: material.errors.full_messages }, status: :unprocessable_entity
+      render_model_errors(material)
     end
   end
 
@@ -68,7 +69,8 @@ class MaterialsController < ApplicationController
     tag_name_raw = params[:tag].to_s.strip
     file = params[:file]
     url = params[:url].to_s.strip.presence
-    return head :bad_request if tag_name_raw.blank? || (file.blank? && url.blank?)
+    return render_bad_request('タグは必須です．', field: :tag) if tag_name_raw.blank?
+    return render_bad_request('ファイルまたは URL は必須です．') if file.blank? && url.blank?
 
     tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
     tag = tag_name.tag
@@ -84,7 +86,7 @@ class MaterialsController < ApplicationController
     if material.save
       render json: MaterialRepr.base(material, host: request.base_url)
     else
-      render json: { errors: material.errors.full_messages }, status: :unprocessable_entity
+      render_model_errors(material)
     end
   end
 

backend/app/controllers/nico_tags_controller.rb

@@ -30,12 +30,14 @@ class NicoTagsController < ApplicationController
     id = params[:id].to_i
 
     tag = Tag.find(id)
-    return head :bad_request unless tag.nico?
+    return render_bad_request('ニコニコ・タグを指定してください．', field: :id) unless tag.nico?
 
     linked_tag_names = params[:tags].to_s.split
     linked_tags = Tag.normalise_tags!(linked_tag_names, with_tagme: false,
                                                         with_no_deerjikist: false)
-    return head :bad_request if linked_tags.any? { |t| t.nico? }
+    if linked_tags.any? { |t| t.nico? }
+      return render_bad_request('ニコニコ・タグ同士は連携できません．', field: :tags)
+    end
 
     ApplicationRecord.transaction do
       TagVersioning.record_tag_snapshots!(linked_tags, created_by_user: current_user)

backend/app/controllers/posts_controller.rb

@@ -44,7 +44,7 @@ class PostsController < ApplicationController
         filtered_posts
         .joins("LEFT JOIN (#{ pt_max_sql }) pt_max ON pt_max.post_id = posts.id")
         .reselect('posts.*', Arel.sql("#{ updated_at_all_sql } AS updated_at_all"))
-        .preload(tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
+        .preload(:uploaded_user, tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
         .with_attached_thumbnail
 
     q = q.where('posts.url LIKE ?', "%#{ url }%") if url
@@ -95,7 +95,9 @@ class PostsController < ApplicationController
   end
 
   def random
-    post = filtered_posts.preload(tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
+    post = filtered_posts.preload(:uploaded_user,
+                                  tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
+                         .with_attached_thumbnail
                          .order('RAND()')
                          .first
     return head :not_found unless post
@@ -104,12 +106,24 @@ class PostsController < ApplicationController
   end
 
   def show
-    post = Post.includes(tags: [:deerjikists, :materials, { tag_name: :wiki_page }]).find_by(id: params[:id])
+    post =
+        Post
+        .includes(:uploaded_user, tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
+        .with_attached_thumbnail
+        .find_by(id: params[:id])
     return head :not_found unless post
 
-    render json: PostRepr.base(post, current_user)
+    parent_posts = post.parents.with_attached_thumbnail.order(:id).to_a
-                         .merge(tags: build_tag_tree_for(post.tags),
+    child_posts = post.children.with_attached_thumbnail.order(:id).to_a
-                                related: PostRepr.many(post.related(limit: 20)))
+    sibling_posts = sibling_posts_by_parent(parent_posts.map(&:id))
+    related = post.related(limit: 20).to_a
+
+    render json: PostRepr.detail(post, current_user,
+                                 parent_posts:,
+                                 child_posts:,
+                                 sibling_posts:,
+                                 related:)
+                         .merge(tags: build_tag_tree_for(post.tags))
   end
 
   def create
@@ -148,11 +162,11 @@ class PostsController < ApplicationController
     post.reload
     render json: PostRepr.base(post), status: :created
   rescue Tag::NicoTagNormalisationError
-    head :bad_request
+    render_validation_error fields: { tags: 'ニコニコ・タグは直接指定できません．' }
   rescue ArgumentError => e
-    render json: { errors: [e.message] }, status: :unprocessable_entity
+    render_validation_error fields: { parent_post_ids: [e.message] }
   rescue ActiveRecord::RecordInvalid => e
-    render json: { errors: e.record.errors.full_messages }, status: :unprocessable_entity
+    render_post_form_record_invalid e.record
   end
 
   def viewed
@@ -175,10 +189,10 @@ class PostsController < ApplicationController
 
     force = bool?(:force)
     merge = bool?(:merge)
-    return head :bad_request if force && merge
+    return render_bad_request('force と merge は同時に指定できません．') if force && merge
 
     base_version_no = parse_base_version_no
-    return head :bad_request if !(force) && !(base_version_no)
+    return render_bad_request('base_version_no は必須です．', field: :base_version_no) if !(force) && !(base_version_no)
 
     title = params[:title].presence
     tag_names = params[:tags].to_s.split
@@ -238,11 +252,11 @@ class PostsController < ApplicationController
     json['tags'] = build_tag_tree_for(post.tags)
     render json:, status: :ok
   rescue Tag::NicoTagNormalisationError
-    head :bad_request
+    render_validation_error fields: { tags: ['ニコニコ・タグは直接指定できません．'] }
   rescue ArgumentError => e
-    render json: { errors: [e.message] }, status: :unprocessable_entity
+    render_validation_error fields: { parent_post_ids: [e.message] }
   rescue ActiveRecord::RecordInvalid => e
-    render json: { errors: e.record.errors.full_messages }, status: :unprocessable_entity
+    render_post_form_record_invalid e.record
   end
 
   def changes
@@ -385,7 +399,7 @@ class PostsController < ApplicationController
       return nil unless tag
 
       if path.include?(tag_id)
-        return TagRepr.base(tag).merge(children: [])
+        return TagRepr.inline(tag).merge(children: [])
       end
 
       if memo.key?(tag_id)
@@ -397,12 +411,26 @@ class PostsController < ApplicationController
 
       children = child_ids.filter_map { |cid| build_node.(cid, new_path) }
 
-      memo[tag_id] = TagRepr.base(tag).merge(children:)
+      memo[tag_id] = TagRepr.inline(tag).merge(children:)
     end
 
     root_ids.filter_map { |id| build_node.call(id, []) }
   end
 
+  def sibling_posts_by_parent parent_post_ids
+    return { } if parent_post_ids.blank?
+
+    implications =
+        PostImplication
+        .where(parent_post_id: parent_post_ids)
+        .includes(post: { thumbnail_attachment: :blob })
+        .order(:parent_post_id, :post_id)
+
+    implications.group_by(&:parent_post_id).transform_values { |items|
+      items.map(&:post)
+    }
+  end
+
   def parse_parent_post_ids
     raise ArgumentError, 'parent_post_ids は必須です．' unless params.key?(:parent_post_ids)
 
@@ -416,7 +444,7 @@ class PostsController < ApplicationController
 
   def sync_parent_posts! post, parent_post_ids
     if parent_post_ids.include?(post.id)
-      post.errors.add(:base, '自分自身を親投稿にはできません．')
+      post.errors.add :parent_post_ids, '自分自身を親投稿にはできません．'
       raise ActiveRecord::RecordInvalid, post
     end
 
@@ -424,7 +452,8 @@ class PostsController < ApplicationController
     missing_ids = parent_post_ids - existing_ids
 
     if missing_ids.present?
-      post.errors.add(:base, "存在しない親投稿 ID があります: #{ missing_ids.join(' ') }")
+      post.errors.add :parent_post_ids,
+                      "存在しない親投稿 ID があります: #{ missing_ids.join(' ') }"
       raise ActiveRecord::RecordInvalid, post
     end
 
@@ -640,4 +669,14 @@ class PostsController < ApplicationController
 
     merged.uniq.sort
   end
+
+  def render_post_form_record_invalid record
+    if e.record.is_a?(TagName) || e.record.is_a?(Tag)
+      render_validation_error(fields: { tags: e.record.errors.full_messages.map { |message|
+        "タグ名 “#{ e.record.name }”: #{ message }"
+      } })
+    else
+      render_validation_error(record)
+    end
+  end
 end

backend/app/controllers/preview_controller.rb

@@ -4,7 +4,7 @@ class PreviewController < ApplicationController
     return head :unauthorized unless current_user
 
     url = params[:url]
-    return head :bad_request unless url.present?
+    return render_bad_request('URL は必須です．', field: :url) unless url.present?
 
     unless url.start_with?(/http(s)?:\/\//)
       url = 'http://' + url
@@ -16,7 +16,7 @@ class PreviewController < ApplicationController
 
     render json: { title: title }
   rescue => e
-    render json: { error: e.message }, status: :bad_request
+    render_bad_request(e.message, field: :url)
   end
 
   def thumbnail
@@ -25,7 +25,7 @@ class PreviewController < ApplicationController
     return head :unauthorized unless current_user
 
     url = params[:url]
-    return head :bad_request if url.blank?
+    return render_bad_request('URL は必須です．', field: :url) if url.blank?
 
     unless url.start_with?(/http(s)?:\/\//)
       url = 'http://' + url
@@ -40,7 +40,8 @@ class PreviewController < ApplicationController
       File.delete(path) rescue nil
       send_file image.path, type: 'image/png', disposition: 'inline'
     else
-      render json: { error: 'Failed to generate thumbnail' }, status: :internal_server_error
+      render_error(:internal_server_error, 'サムネールを生成できませんでした．',
+                   code: :thumbnail_generation_failed)
     end
   end
 end

backend/app/controllers/tag_children_controller.rb

@@ -5,11 +5,12 @@ class TagChildrenController < ApplicationController
 
     parent_id = params[:parent_id]
     child_id = params[:child_id]
-    return head :bad_request if parent_id.blank? || child_id.blank?
+    return render_bad_request('parent_id は必須です．', field: :parent_id) if parent_id.blank?
+    return render_bad_request('child_id は必須です．', field: :child_id) if child_id.blank?
 
     parent = Tag.find(parent_id)
     child = Tag.find(child_id)
-    return head :bad_request if parent.nico? || child.nico?
+    return render_bad_request('ニコニコ・タグの階層は変更できません．') if parent.nico? || child.nico?
 
     ApplicationRecord.transaction do
       TagVersioning.ensure_snapshot!(child, created_by_user: current_user)
@@ -27,11 +28,12 @@ class TagChildrenController < ApplicationController
 
     parent_id = params[:parent_id]
     child_id = params[:child_id]
-    return head :bad_request if parent_id.blank? || child_id.blank?
+    return render_bad_request('parent_id は必須です．', field: :parent_id) if parent_id.blank?
+    return render_bad_request('child_id は必須です．', field: :child_id) if child_id.blank?
 
     parent = Tag.find(parent_id)
     child = Tag.find(child_id)
-    return head :bad_request if parent.nico? || child.nico?
+    return render_bad_request('ニコニコ・タグの階層は変更できません．') if parent.nico? || child.nico?
 
     ApplicationRecord.transaction do
       TagVersioning.ensure_snapshot!(child, created_by_user: current_user)

backend/app/controllers/tags_controller.rb

@@ -168,7 +168,7 @@ class TagsController < ApplicationController
 
   def show_by_name
     name = params[:name].to_s.strip
-    return head :bad_request if name.blank?
+    return render_bad_request('name は必須です．', field: :name) if name.blank?
 
     tag = Tag.joins(:tag_name)
              .includes(:tag_name, :materials, tag_name: :wiki_page)
@@ -192,7 +192,7 @@ class TagsController < ApplicationController
 
   def deerjikists_by_name
     name = params[:name].to_s.strip
-    return head :bad_request if name.blank?
+    return render_bad_request('name は必須です．', field: :name) if name.blank?
 
     tag = Tag.joins(:tag_name)
              .includes(:tag_name, tag_name: :wiki_page)
@@ -228,7 +228,7 @@ class TagsController < ApplicationController
 
   def materials_by_name
     name = params[:name].to_s.strip
-    return head :bad_request if name.blank?
+    return render_bad_request('name は必須です．', field: :name) if name.blank?
 
     tag = Tag.joins(:tag_name)
              .includes(:tag_name, :materials, tag_name: :wiki_page)
@@ -247,17 +247,16 @@ class TagsController < ApplicationController
 
     name = params[:name].to_s.strip
     category = params[:category].to_s.strip
-    return head :unprocessable_entity if name.blank? || category.blank?
+    return render_unprocessable_entity('名前は必須です．', field: :name) if name.blank?
+    return render_unprocessable_entity('カテゴリは必須です．', field: :category) if category.blank?
 
     if name != tag.name &&
         tag.in?([Tag.tagme, Tag.bot, Tag.no_deerjikist, Tag.video, Tag.niconico])
-      return render json: { error: 'システム・タグの名称は変更できません．' },
+      return render_unprocessable_entity('システム・タグの名称は変更できません．', field: :name)
-                    status: :unprocessable_entity
     end
 
     if tag.nico? || category == 'nico'
-      return render json: { error: 'ニコタグは変更できません．' },
+      return render_unprocessable_entity('ニコタグは変更できません．', field: :category)
-                    status: :unprocessable_entity
     end
 
     alias_names = params[:aliases].to_s.split.uniq
@@ -302,8 +301,7 @@ class TagsController < ApplicationController
     tag = Tag.find(params[:id])
 
     if tag.nico? || (category.present? && category == 'nico')
-      return render json: { error: 'ニコタグは変更できません．' },
+      return render_unprocessable_entity('ニコタグは変更できません．', field: :category)
-                    status: :unprocessable_entity
     end
 
     ApplicationRecord.transaction do

backend/app/controllers/theatre_comments_controller.rb

@@ -15,7 +15,7 @@ class TheatreCommentsController < ApplicationController
     return head :unauthorized unless current_user
 
     content = params[:content]
-    return head :unprocessable_entity if content.blank?
+    return render_unprocessable_entity('本文は必須です．', field: :content) if content.blank?
 
     theatre = Theatre.find_by(id: params[:theatre_id])
     return head :not_found unless theatre

backend/app/controllers/users_controller.rb

@@ -42,12 +42,12 @@ class UsersController < ApplicationController
     return head :unauthorized if user&.id != params[:id].to_i
 
     name = params[:name]
-    return head :bad_request if name.blank?
+    return render_bad_request('名前は必須です．', field: :name) if name.blank?
 
     if user.update(name:)
       render json: user.slice(:id, :name, :inheritance_code, :role), status: :ok
     else
-      render json: user.errors, status: :unprocessable_entity
+      render_model_errors(user)
     end
   end
 

backend/app/controllers/wiki_pages_controller.rb

@@ -46,7 +46,7 @@ class WikiPagesController < ApplicationController
 
   def diff
     id = params[:id]
-    return head :bad_request if id.blank?
+    return render_bad_request('id は必須です．', field: :id) if id.blank?
 
     from = params[:from].presence
     to = params[:to].presence
@@ -56,7 +56,7 @@ class WikiPagesController < ApplicationController
     from_rev = from && page.wiki_revisions.find(from)
     to_rev = to ? page.wiki_revisions.find(to) : page.current_revision
     if ((from_rev && !(from_rev.content?)) || !(to_rev&.content?))
-      return head :unprocessable_entity
+      return render_unprocessable_entity('差分を表示できない版です．')
     end
 
     diffs = Diff::LCS.sdiff(from_rev&.body&.lines || [], to_rev.body.lines)
@@ -89,7 +89,8 @@ class WikiPagesController < ApplicationController
     body = params[:body].to_s
     message = params[:message].presence
 
-    return head :unprocessable_entity if title.blank? || body.blank?
+    return render_unprocessable_entity('タイトルは必須です．', field: :title) if title.blank?
+    return render_unprocessable_entity('本文は必須です．', field: :body) if body.blank?
 
     tag_name = TagName.find_undiscard_or_create_by!(name: title)
 
@@ -101,8 +102,10 @@ class WikiPagesController < ApplicationController
             message:)
 
     render json: WikiPageRepr.base(page), status: :created
-  rescue ActiveRecord::RecordInvalid, ActiveRecord::RecordNotUnique
+  rescue ActiveRecord::RecordInvalid => e
-    head :unprocessable_entity
+    render_model_errors(e.record)
+  rescue ActiveRecord::RecordNotUnique
+    render_record_not_unique
   end
 
   def update
@@ -112,7 +115,8 @@ class WikiPagesController < ApplicationController
     title = params[:title]&.strip
     body = params[:body].to_s
 
-    return head :unprocessable_entity if title.blank? || body.blank?
+    return render_unprocessable_entity('タイトルは必須です．', field: :title) if title.blank?
+    return render_unprocessable_entity('本文は必須です．', field: :body) if body.blank?
 
     page = WikiPage.find(params[:id])
     base_revision_id = params[:base_revision_id].presence

backend/app/models/post.rb

@@ -94,7 +94,7 @@ class Post < ApplicationRecord
     return if !(f) || !(b)
 
     if f >= b
-      errors.add :original_created_before, 'オリジナルの作成日時の順番がをかしぃです．'
+      errors.add :original_created_at, 'オリジナルの作成日時の順番がをかしぃです．'
     end
   end
 

backend/app/representations/post_repr.rb

@@ -2,20 +2,65 @@
 
 
 module PostRepr
-  BASE = { include: { tags: TagRepr::BASE, uploaded_user: UserRepr::BASE },
+  BASE_FIELDS = [
-           methods: [:parent_posts, :child_posts, :sibling_posts] }.freeze
+      :id,
+      :version_no,
+      :url,
+      :title,
+      :thumbnail_base,
+      :original_created_from,
+      :original_created_before,
+      :created_at,
+      :updated_at
+  ].freeze
 
   module_function
 
   def base post, current_user = nil
-    json = post.as_json(BASE)
+    json = common(post)
-    return json.merge(viewed: false) unless current_user
+    json['tags'] = tag_json(post.tags)
+    json['uploaded_user'] = post.uploaded_user && UserRepr.base(post.uploaded_user)
+    json['viewed'] = current_user ? current_user.viewed?(post) : false
+    json
+  end
 
-    viewed = current_user.viewed?(post)
+  def detail post, current_user = nil, parent_posts: [], child_posts: [],
-    json.merge(viewed:)
+             sibling_posts: { }, related: []
+    base(post, current_user).merge(
+        'parent_posts' => cards(parent_posts),
+        'child_posts' => cards(child_posts),
+        'sibling_posts' => sibling_posts.transform_keys(&:to_s).transform_values { |posts|
+          cards(posts)
+        },
+        'related' => cards(related))
+  end
+
+  def card post
+    common(post).merge('parent_posts' => [], 'child_posts' => [])
+  end
+
+  def cards posts
+    posts.map { |post| card(post) }
   end
 
   def many posts, current_user = nil
     posts.map { |p| base(p, current_user) }
   end
+
+  def common post
+    BASE_FIELDS.to_h { |field| [field.to_s, post.public_send(field)] }
+               .merge('thumbnail' => thumbnail_url(post))
+  end
+
+  def tag_json tags
+    tags.map { |tag| TagRepr.inline(tag) }
+  end
+
+  def thumbnail_url post
+    return nil unless post.thumbnail.attached?
+
+    Rails.application.routes.url_helpers.rails_blob_url(post.thumbnail, only_path: false)
+  rescue
+    nil
+  end
 end

backend/app/representations/tag_repr.rb

@@ -12,5 +12,9 @@ module TagRepr
                             parents: tag.parents.map { _1.as_json(BASE) })
   end
 
+  def inline tag
+    tag.as_json(BASE).merge(aliases: [], parents: [])
+  end
+
   def many(tags) = tags.map { |t| base(t) }
 end

backend/spec/requests/error_responses_spec.rb

@@ -0,0 +1,47 @@
+require 'rails_helper'
+
+RSpec.describe 'error responses', type: :request do
+  describe 'manual input errors' do
+    it 'returns a stable errors array for bad requests' do
+      user = create(:user)
+      sign_in_as(user)
+
+      put "/users/#{ user.id }", params: { name: '   ' }
+
+      expect(response).to have_http_status(:bad_request)
+      expect(json.fetch('errors')).to contain_exactly(
+          include('code' => 'bad_request',
+                  'field' => 'name',
+                  'message' => be_present))
+    end
+
+    it 'returns a stable errors array for unprocessable requests' do
+      member = create(:user, :member)
+      tag = create(:tag, :general, name: 'error_response_tag')
+      sign_in_as(member)
+
+      patch "/tags/#{ tag.id }", params: { category: 'nico' }
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to contain_exactly(
+          include('code' => 'invalid',
+                  'field' => 'category',
+                  'message' => be_present))
+    end
+  end
+
+  describe 'model validation errors' do
+    it 'returns field, code, and message for model errors' do
+      user = create(:user)
+      sign_in_as(user)
+
+      put "/users/#{ user.id }", params: { name: 'a' * 256 }
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to include(
+          include('code' => 'too_long',
+                  'field' => 'name',
+                  'message' => be_present))
+    end
+  end
+end

backend/spec/requests/posts_spec.rb

@@ -57,6 +57,23 @@ RSpec.describe 'Posts API', type: :request do
     post_write_params({ base_version_no: base_version.version_no }.merge(params))
   end
 
+  def count_sql_queries
+    count = 0
+
+    callback = lambda do |_name, _started, _finished, _id, payload|
+      next if payload[:cached]
+      next if ['SCHEMA', 'TRANSACTION'].include?(payload[:name])
+
+      count += 1
+    end
+
+    ActiveSupport::Notifications.subscribed(callback, 'sql.active_record') do
+      yield
+    end
+
+    count
+  end
+
   let!(:tag_name) { TagName.create!(name: 'spec_tag') }
   let!(:tag)      { Tag.create!(tag_name: tag_name, category: :general) }
 
@@ -558,6 +575,59 @@ RSpec.describe 'Posts API', type: :request do
           expect(sibling_ids).to include(sibling_post.id)
         end
       end
+
+      it 'does not issue a query per tag or related post' do
+        user = create_member_user!
+
+        tags =
+            15.times.map do |i|
+              tag_name = TagName.create!(name: "show_query_tag_#{ i }")
+              tag = Tag.create!(tag_name:, category: :general)
+              TagName.create!(name: "show_query_alias_#{ i }", canonical: tag_name)
+              PostTag.create!(post: post_record, tag:)
+              tag
+            end
+
+        tags.each_cons(2) do |parent_tag, child_tag|
+          TagImplication.create!(parent_tag:, tag: child_tag)
+        end
+
+        parent_post = Post.create!(
+          title: 'query parent post',
+          url: 'https://example.com/query-parent-post'
+        )
+        sibling_post = Post.create!(
+          title: 'query sibling post',
+          url: 'https://example.com/query-sibling-post'
+        )
+        child_post = Post.create!(
+          title: 'query child post',
+          url: 'https://example.com/query-child-post'
+        )
+
+        PostImplication.create!(post: post_record, parent_post:)
+        PostImplication.create!(post: sibling_post, parent_post:)
+        PostImplication.create!(post: child_post, parent_post: post_record)
+
+        20.times do |i|
+          related_post = Post.create!(
+            title: "query related post #{ i }",
+            url: "https://example.com/query-related-post-#{ i }"
+          )
+          PostSimilarity.create!(post: post_record,
+                                 target_post: related_post,
+                                 cos: 1.0 - (i / 100.0))
+        end
+
+        query_count =
+            count_sql_queries do
+              get "/posts/#{ post_record.id }",
+                  headers: { 'X-Transfer-Code' => user.inheritance_code }
+            end
+
+        expect(response).to have_http_status(:ok)
+        expect(query_count).to be <= 45
+      end
     end
 
     context 'when post does not exist' do

frontend/src/components/PostEditForm.tsx

@@ -2,17 +2,24 @@ import { useEffect, useState } from 'react'
 
 import PostFormTagsArea from '@/components/PostFormTagsArea'
 import PostOriginalCreatedTimeField from '@/components/PostOriginalCreatedTimeField'
+import FieldError from '@/components/common/FieldError'
 import Label from '@/components/common/Label'
 import { useDialogue } from '@/components/dialogues/DialogueProvider'
 import { Button } from '@/components/ui/button'
 import { toast } from '@/components/ui/use-toast'
 import { isApiError } from '@/lib/api'
+import { extractValidationError } from '@/lib/apiErrors'
 import { updatePost } from '@/lib/posts'
+import { inputClass } from '@/lib/utils'
 
 import type { FC, FormEvent } from 'react'
 
+import type { FieldErrors } from '@/lib/apiErrors'
 import type { Post, Tag } from '@/types'
 
+type PostFormField =
+    'parentPostId' | 'tags' | 'originalCreatedFrom' | 'originalCreatedBefore'
+
 
 const tagsToStr = (tags: Tag[]): string => {
   const result: Tag[] = []
@@ -34,7 +41,9 @@ type Props = { post:    Post
 
 
 const PostEditForm: FC<Props> = ({ post, onSave }) => {
+  const [baseErrors, setBaseErrors] = useState<string[]> ([])
   const [disabled, setDisabled] = useState (false)
+  const [fieldErrors, setFieldErrors] = useState<FieldErrors> ({ })
   const [originalCreatedBefore, setOriginalCreatedBefore] =
       useState<string | null> (post.originalCreatedBefore)
   const [originalCreatedFrom, setOriginalCreatedFrom] =
@@ -47,6 +56,9 @@ const PostEditForm: FC<Props> = ({ post, onSave }) => {
   const dialogue = useDialogue ()
 
   const update = async (...args: Parameters<typeof updatePost>) => {
+    setFieldErrors ({ })
+    setBaseErrors ([])
+
     try
     {
       const data = await updatePost (...args)
@@ -67,7 +79,18 @@ const PostEditForm: FC<Props> = ({ post, onSave }) => {
 
       if (response?.status !== 409)
 	{
-	  toast ({ description: '更新はできなかったよ……' })
+	  const validationError = extractValidationError<PostFormField> (e)
+
+	  if (validationError)
+	    {
+	      setFieldErrors (validationError.fieldErrors)
+	      setBaseErrors (validationError.baseErrors)
+	      toast ({ description: '更新はできなかったよ……' })
+	      return
+	    }
+
+	  toast ({ title: '失敗……', description: '入力を確認してください．' })
+
 	  return
 	}
 
@@ -122,33 +145,41 @@ const PostEditForm: FC<Props> = ({ post, onSave }) => {
 
   return (
       <form onSubmit={handleSubmit} className="max-w-xl pt-2 space-y-4">
+	<FieldError messages={baseErrors}/>
+
 	{/* タイトル */}
 	<div>
 	  <Label>タイトル</Label>
 	  <input
 	      type="text"
 	      disabled={disabled}
-	      className="w-full border rounded p-2"
+	      className={inputClass ()}
 	      value={title ?? ''}
 	      onChange={ev => setTitle (ev.target.value)}/>
 	</div>
 
 	{/* 親投稿 */}
 	<div>
-	  <Label>親投稿</Label>
+	  <Label invalid={fieldErrors.parentPostIds && fieldErrors.parentPostIds.length > 0}>
+	    親投稿
+	  </Label>
 	  <input
 	      type="text"
 	      disabled={disabled}
 	      value={parentPostIds}
 	      onChange={e => setParentPostIds (e.target.value)}
-	      className="w-full border p-2 rounded"/>
+	      aria-invalid={fieldErrors.parentPostIds && fieldErrors.parentPostIds.length > 0}
+	      className={inputClass (fieldErrors.parentPostIds
+				     && fieldErrors.parentPostIds.length > 0)}/>
+	  <FieldError messages={fieldErrors.parentPostIds}/>
 	</div>
 
 	{/* タグ */}
 	<PostFormTagsArea
 	    disabled={disabled}
 	    tags={tags}
-	    setTags={setTags}/>
+	    setTags={setTags}
+	    errors={fieldErrors.tags}/>
 
 	{/* オリジナルの作成日時 */}
 	<PostOriginalCreatedTimeField
@@ -156,15 +187,14 @@ const PostEditForm: FC<Props> = ({ post, onSave }) => {
 	    originalCreatedFrom={originalCreatedFrom}
 	    setOriginalCreatedFrom={setOriginalCreatedFrom}
 	    originalCreatedBefore={originalCreatedBefore}
-	    setOriginalCreatedBefore={setOriginalCreatedBefore}/>
+	    setOriginalCreatedBefore={setOriginalCreatedBefore}
+	    errors={fieldErrors.originalCreatedAt}/>
 
 	{/* 送信 */}
-	<Button
+	<Button type="submit" disabled={disabled}>
-	    type="submit"
-	    disabled={disabled}>
 	  更新
 	</Button>
       </form>)
 }
 
-export default PostEditForm
+export default PostEditForm

frontend/src/components/PostFormTagsArea.tsx

@@ -3,6 +3,7 @@
 import { useRef, useState } from 'react'
 
 import TagSearchBox from '@/components/TagSearchBox'
+import FieldError from '@/components/common/FieldError'
 import Label from '@/components/common/Label'
 import TextArea from '@/components/common/TextArea'
 import { apiGet } from '@/lib/api'
@@ -33,10 +34,11 @@ const replaceToken = (value: string, start: number, end: number, text: string) =
 
 type Props = Omit<ComponentPropsWithoutRef<'textarea'>, 'value' | 'onChange' | 'onBlur'> & {
     tags:     string
-    setTags:  (tags: string) => void }
+    setTags:  (tags: string) => void
+    errors?:  string[] }
 
 
-const PostFormTagsArea: FC<Props> = ({ tags, setTags, ...rest }) => {
+const PostFormTagsArea: FC<Props> = ({ tags, setTags, errors, ...rest }) => {
   const ref = useRef<HTMLTextAreaElement> (null)
 
   const [bounds, setBounds] = useState<{ start: number; end: number }> ({ start: 0, end: 0 })
@@ -74,11 +76,12 @@ const PostFormTagsArea: FC<Props> = ({ tags, setTags, ...rest }) => {
 
   return (
       <div className="relative w-full">
-	<Label>タグ</Label>
+	<Label invalid={errors && errors.length > 0}>タグ</Label>
 	<TextArea
 	    {...rest}
 	    ref={ref}
 	    value={tags}
+	    invalid={errors && errors.length > 0}
 	    onChange={ev => setTags (ev.target.value)}
 	    onSelect={async (ev: SyntheticEvent<HTMLTextAreaElement>) => {
 	      const pos = (ev.target as HTMLTextAreaElement).selectionStart
@@ -96,7 +99,8 @@ const PostFormTagsArea: FC<Props> = ({ tags, setTags, ...rest }) => {
 			     : [] as Tag[]}
 		activeIndex={-1}
 		onSelect={handleTagSelect}/>)}
+	<FieldError messages={errors}/>
       </div>)
 }
 
-export default PostFormTagsArea
+export default PostFormTagsArea

frontend/src/components/PostOriginalCreatedTimeField.tsx

@@ -1,4 +1,5 @@
 import DateTimeField from '@/components/common/DateTimeField'
+import { FieldError } from '@/components/common/FieldError'
 import Label from '@/components/common/Label'
 import { Button } from '@/components/ui/button'
 
@@ -9,21 +10,28 @@ type Props = {
     originalCreatedFrom:      string | null
     setOriginalCreatedFrom:   (x: string | null) => void
     originalCreatedBefore:    string | null
-    setOriginalCreatedBefore: (x: string | null) => void }
+    setOriginalCreatedBefore: (x: string | null) => void
+    errors?:                  string[] }
 
 
-const PostOriginalCreatedTimeField: FC<Props> = ({ disabled,
+const PostOriginalCreatedTimeField: FC<Props> = (
-		   originalCreatedFrom,
+    { disabled,
-		   setOriginalCreatedFrom,
+      originalCreatedFrom,
-		   originalCreatedBefore,
+      setOriginalCreatedFrom,
-		   setOriginalCreatedBefore }) => (
+      originalCreatedBefore,
+      setOriginalCreatedBefore,
+      errors }: Props,
+) => (
     <div>
-      <Label>オリジナルの作成日時</Label>
+      <Label invalid={errors && errors.length > 0}>オリジナルの作成日時</Label>
+
       <div className="my-1 flex">
 	<div className="w-80">
 	  <DateTimeField
 	      className="mr-2"
 	      disabled={disabled ?? false}
+	      aria-invalid={errors && errors.length > 0}
+	      invalid={errors && errors.length > 0}
 	      value={originalCreatedFrom ?? undefined}
 	      onChange={setOriginalCreatedFrom}
 	      onBlur={ev => {
@@ -51,11 +59,14 @@ const PostOriginalCreatedTimeField: FC<Props> = ({ disabled,
 	  </Button>
 	</div>
       </div>
+
       <div className="my-1 flex">
 	<div className="w-80">
 	  <DateTimeField
 	      className="mr-2"
 	      disabled={disabled}
+	      aria-invalid={errors && errors.length > 0}
+	      invalid={errors && errors.length > 0}
 	      value={originalCreatedBefore ?? undefined}
 	      onChange={setOriginalCreatedBefore}/>
 	  より前
@@ -71,6 +82,8 @@ const PostOriginalCreatedTimeField: FC<Props> = ({ disabled,
 	  </Button>
 	</div>
       </div>
+
+      <FieldError messages={errors}/>
     </div>)
 
-export default PostOriginalCreatedTimeField
+export default PostOriginalCreatedTimeField

frontend/src/components/common/DateTimeField.tsx

@@ -22,10 +22,11 @@ type Props = Omit<ComponentPropsWithoutRef<'input'>, 'onChange'> & {
     value?:     string
     onChange?:  (isoUTC: string | null) => void
     className?: string
-    onBlur?:    (ev: FocusEvent<HTMLInputElement>) => void }
+    onBlur?:    (ev: FocusEvent<HTMLInputElement>) => void
+    invalid?:   boolean }
 
 
-const DateTimeField: FC<Props> = ({ value, onChange, className, onBlur, ...rest }) => {
+const DateTimeField: FC<Props> = ({ value, onChange, className, onBlur, invalid, ...rest }) => {
   const [local, setLocal] = useState ('')
 
   useEffect (() => {
@@ -35,9 +36,19 @@ const DateTimeField: FC<Props> = ({ value, onChange, className, onBlur, ...rest
   return (
       <input
 	  {...rest}
-	  className={cn ('border rounded p-2', className)}
+	  className={cn ('border rounded p-2',
+			 (invalid
+			  ? ['border-red-500 bg-red-50 text-red-900',
+			     'focus:border-red-500 focus:outline-none',
+			     'focus:ring-2 focus:ring-red-200',
+			     'dark:border-red-500 dark:bg-red-950/30 dark:text-red-100']
+			  : ['border-gray-300',
+			     'focus:border-blue-500 focus:outline-none',
+			     'focus:ring-2 focus:ring-blue-200']),
+			 className)}
 	  type="datetime-local"
 	  value={local}
+	  aria-invalid={invalid}
 	  onChange={ev => {
 	    const v = ev.target.value
 	    setLocal (v)
@@ -46,4 +57,4 @@ const DateTimeField: FC<Props> = ({ value, onChange, className, onBlur, ...rest
 	  onBlur={onBlur}/>)
 }
 
-export default DateTimeField
+export default DateTimeField

frontend/src/components/common/FieldError.tsx

@@ -0,0 +1,17 @@
+import type { FC } from 'react'
+
+type Props = { messages?: string[] }
+
+
+export const FieldError: FC<Props> = ({ messages }: Props) => {
+  if (!(messages) || messages.length === 0)
+    return null
+
+  return (
+      <ul className="mt-1 space-y-1 text-red-700 dark:text-red-300">
+	{messages.map ((message, i) => <li key={i}>{message}</li>)}
+      </ul>)
+}
+
+
+export default FieldError

frontend/src/components/common/Label.tsx

@@ -1,32 +1,39 @@
 import React from 'react'
 
+import { cn } from '@/lib/utils'
+
 import type { FC } from 'react'
 
 type Props = { children:  React.ReactNode
-               checkBox?: { label:    string
+	       checkBox?: { label:    string
-                            checked:  boolean
+			    checked:  boolean
-                            onChange: (event: React.ChangeEvent<HTMLInputElement>) => void } }
+			    onChange: (event: React.ChangeEvent<HTMLInputElement>) => void }
+	       invalid?:  boolean }
 
 
-const Label: FC<Props> = ({ children, checkBox }) => {
+const Label: FC<Props> = ({ children, checkBox, invalid }: Props) => {
+  const labelClassName = cn ('block font-semibold mb-1',
+			     invalid && 'text-red-700 dark:text-red-300')
+
   if (!(checkBox))
     {
       return (
-          <label className="block font-semibold mb-1">
+	  <label className={labelClassName}>
-            {children}
+	    {children}
-          </label>)
+	  </label>)
     }
 
   return (
       <div className="flex gap-2 mb-1">
-        <label className="flex-1 block font-semibold">{children}</label>
+	<label className="flex-1 block font-semibold">{children}</label>
-        <label className="flex items-center block gap-1">
+	<label className="flex items-center block gap-1">
-          <input type="checkbox"
+	  <input type="checkbox"
-                 checked={checkBox.checked}
+		 checked={checkBox.checked}
-                 onChange={checkBox.onChange}/>
+		 onChange={checkBox.onChange}/>
-          {checkBox.label}
+	  {checkBox.label}
-        </label>
+	</label>
       </div>)
 }
 
+
 export default Label

frontend/src/components/common/TextArea.tsx

@@ -1,9 +1,25 @@
 import { forwardRef } from 'react'
 
+import { cn } from '@/lib/utils'
+
 import type { TextareaHTMLAttributes } from 'react'
 
-type Props = TextareaHTMLAttributes<HTMLTextAreaElement>
+type Props = TextareaHTMLAttributes<HTMLTextAreaElement> & { invalid?: boolean }
 
 
-export default forwardRef<HTMLTextAreaElement, Props> (({ ...props }, ref) => (
+export default forwardRef<HTMLTextAreaElement, Props> (
-    <textarea ref={ref} className="rounded border w-full p-2 h-32" {...props}/>))
+    ({ className, invalid = false, ...props }, ref) => (
+	<textarea
+	    ref={ref}
+	    aria-invalid={invalid}
+	    className={cn ('rounded border w-full p-2 h-32',
+			   (invalid
+			    ? ['border-red-500 bg-red-50 text-red-900',
+			       'focus:border-red-500 focus:outline-none focus:ring-2',
+			       'foucs:ring-red-200',
+			       'dark:border-red-500 dark:bg-red-950/30 dark:text-red-100']
+			    : ['border-gray-300',
+			       'focus:border-blue-500 focus:outline-none focus:ring-2',
+			       'focus:ring-blue-200']),
+			   className)}
+	    {...props}/>))

frontend/src/lib/apiErrors.ts

@@ -0,0 +1,31 @@
+import toCamel from 'camelcase-keys'
+
+import { isApiError } from '@/lib/api'
+
+export type FieldErrors<T extends string = string> = Partial<Record<T, string[]>>
+
+export type ValidationError<T extends string = string> =
+    { message:      string
+      fieldErrors:  FieldErrors<T>
+      baseErrors:   string[] }
+
+type RawValidationError = { type?:        string
+			    message?:     string
+			    errors?:      Record<string, string[]>
+			    baseErrors?:  string[] }
+
+
+export const extractValidationError = <T extends string = string> (err: unknown) => {
+  if (!(isApiError (err)) || err.response?.status !== 422)
+    return null
+
+  const data = toCamel ((err.response.data ?? { }) as Record<string, unknown>,
+			{ deep: true }) as RawValidationError
+
+  if (data.type !== 'validation_error' && !(data.errors))
+    return null
+
+  return { message: data.message ?? '入力内容を確認してください．',
+	   fieldErrors: (data.errors ?? { }) as FieldErrors<T>,
+	   baseErrors: data.baseErrors ?? [] }
+}

frontend/src/lib/users.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, it } from 'vitest'
+
+import { canEditContent } from '@/lib/users'
+
+import type { UserRole } from '@/types'
+
+const userWithRole = (role: UserRole) => ({ role })
+
+describe ('user permission helpers', () => {
+  it ('allows admins and members to edit content', () => {
+    expect (canEditContent (userWithRole ('admin'))).toBe (true)
+    expect (canEditContent (userWithRole ('member'))).toBe (true)
+  })
+
+  it ('does not allow guests or missing users to edit content', () => {
+    expect (canEditContent (userWithRole ('guest'))).toBe (false)
+    expect (canEditContent (null)).toBe (false)
+    expect (canEditContent (undefined)).toBe (false)
+  })
+})

frontend/src/lib/users.ts

@@ -0,0 +1,7 @@
+import type { User, UserRole } from '@/types'
+
+const CONTENT_EDITOR_ROLES: readonly UserRole[] = ['admin', 'member']
+
+export const canEditContent = (
+    user: Pick<User, 'role'> | null | undefined,
+): boolean => user != null && CONTENT_EDITOR_ROLES.includes (user.role)

frontend/src/lib/utils.ts

@@ -71,3 +71,15 @@ export const originalCreatedAtString = (
 	       .join (' '))
   return rtn === '〜' ? '年月日不詳' : rtn
 }
+
+
+export const inputClass = (invalid?: boolean, className?: string): string =>
+    cn ('w-full rounded border p-2',
+	(invalid
+	 ? ['border-red-500 bg-red-50 text-red-900',
+	    'placeholder:text-red-300',
+	    'focus:border-red-500 focus:outline-none focus:ring-2 focus:ring-red-200',
+	    'dark:border-red-500 dark:bg-red-950/30 dark:text-red-100']
+	 : ['border-gray-300',
+	    'focus:border-blue-500 focus:outline-none focus:ring-2 focus:ring-blue-200']),
+	className)

frontend/src/pages/posts/PostDetailPage.tsx

@@ -3,7 +3,6 @@ import { motion } from 'framer-motion'
 import { useEffect, useRef, useState } from 'react'
 import { Helmet } from 'react-helmet-async'
 import { useParams } from 'react-router-dom'
-
 import PostEditForm from '@/components/PostEditForm'
 import PostEmbed from '@/components/PostEmbed'
 import PostList from '@/components/PostList'
@@ -16,6 +15,7 @@ import { SITE_TITLE } from '@/config'
 import { isApiError } from '@/lib/api'
 import { fetchPost, toggleViewedFlg } from '@/lib/posts'
 import { postsKeys, tagsKeys } from '@/lib/queryKeys'
+import { canEditContent } from '@/lib/users'
 import { cn } from '@/lib/utils'
 import NotFound from '@/pages/NotFound'
 import ServiceUnavailable from '@/pages/ServiceUnavailable'
@@ -28,6 +28,7 @@ type Props = { user: User | null }
 
 
 const PostDetailPage: FC<Props> = ({ user }) => {
+  const editable = canEditContent (user)
   const { id } = useParams ()
   const postId = String (id ?? '')
   const postKey = postsKeys.show (postId)
@@ -164,7 +165,7 @@ const PostDetailPage: FC<Props> = ({ user }) => {
 		     ? <PostList posts={post.related}/>
 		     : 'まだないよ（笑）'}
 		  </Tab>
-		  {['admin', 'member'].some (r => user?.role === r) && (
+		  {editable && (
 		      <Tab name="編輯">
 			<PostEditForm
 			    post={post}

frontend/src/pages/posts/PostNewPage.tsx

@@ -12,6 +12,7 @@ import { Button } from '@/components/ui/button'
 import { toast } from '@/components/ui/use-toast'
 import { SITE_TITLE } from '@/config'
 import { apiGet, apiPost } from '@/lib/api'
+import { canEditContent } from '@/lib/users'
 import Forbidden from '@/pages/Forbidden'
 
 import type { FC } from 'react'
@@ -22,7 +23,7 @@ type Props = { user: User | null }
 
 
 const PostNewPage: FC<Props> = ({ user }) => {
-  const editable = ['admin', 'member'].some (r => user?.role === r)
+  const editable = canEditContent (user)
 
   const navigate = useNavigate ()
 

frontend/src/pages/tags/NicoTagListPage.tsx

@@ -10,6 +10,7 @@ import MainArea from '@/components/layout/MainArea'
 import { toast } from '@/components/ui/use-toast'
 import { SITE_TITLE } from '@/config'
 import { apiGet, apiPut } from '@/lib/api'
+import { canEditContent } from '@/lib/users'
 
 import type { NicoTag, Tag, User } from '@/types'
 
@@ -25,7 +26,7 @@ const NicoTagListPage: FC<Props> = ({ user }) => {
 
   const loaderRef = useRef<HTMLDivElement | null> (null)
 
-  const memberFlg = ['admin', 'member'].some (r => user?.role === r)
+  const editable = canEditContent (user)
 
   const applyLoadedTags = useCallback ((data: { tags: NicoTag[]; nextCursor: string },
 					withCursor: boolean) => {
@@ -117,7 +118,7 @@ const NicoTagListPage: FC<Props> = ({ user }) => {
 		  <tr>
 		    <th className="p-2 text-left">ニコニコタグ</th>
 		    <th className="p-2 text-left">連携タグ</th>
-		    {memberFlg && <th></th>}
+		    {editable && <th></th>}
 		  </tr>
 		</thead>
 		<tbody>
@@ -139,7 +140,7 @@ const NicoTagListPage: FC<Props> = ({ user }) => {
 					 withCount={false}/>
 			      </span>))}
 			</td>
-			{memberFlg && (
+			{editable && (
 			    <td className="p-2">
 			      <a href="#" onClick={ev => {
 				ev.preventDefault ()

frontend/src/pages/wiki/WikiEditPage.tsx

@@ -10,6 +10,7 @@ import { toast } from '@/components/ui/use-toast'
 import { SITE_TITLE } from '@/config'
 import { apiGet, apiPut } from '@/lib/api'
 import { wikiKeys } from '@/lib/queryKeys'
+import { canEditContent } from '@/lib/users'
 import Forbidden from '@/pages/Forbidden'
 
 import 'react-markdown-editor-lite/lib/index.css'
@@ -24,7 +25,7 @@ type Props = { user: User | null }
 
 
 const WikiEditPage: FC<Props> = ({ user }) => {
-  const editable = ['admin', 'member'].some (r => user?.role === r)
+  const editable = canEditContent (user)
 
   const { id } = useParams ()
 

frontend/src/pages/wiki/WikiNewPage.tsx

@@ -10,6 +10,7 @@ import MainArea from '@/components/layout/MainArea'
 import { toast } from '@/components/ui/use-toast'
 import { SITE_TITLE } from '@/config'
 import { apiPost } from '@/lib/api'
+import { canEditContent } from '@/lib/users'
 import Forbidden from '@/pages/Forbidden'
 
 import 'react-markdown-editor-lite/lib/index.css'
@@ -22,7 +23,7 @@ type Props = { user: User | null }
 
 
 const WikiNewPage: FC<Props> = ({ user }) => {
-  const editable = ['admin', 'member'].some (r => user?.role === r)
+  const editable = canEditContent (user)
 
   const location = useLocation ()
   const navigate = useNavigate ()