#294

Merge branch 'main' into feature/308

#308

#308

#308

#308

Co-authored-by: miteruzo <miteruzo@naver.com>
Reviewed-on: #315

backend/Gemfile

@@ -50,8 +50,6 @@ group :development, :test do
   gem 'factory_bot_rails'
 end
 
-
-
 gem "mysql2", "~> 0.5.6"
 
 gem "image_processing", "~> 1.14"
@@ -69,3 +67,5 @@ gem 'whenever', require: false
 gem 'discard'
 
 gem "rspec-rails", "~> 8.0", :groups => [:development, :test]
+
+gem 'aws-sdk-s3', require: false

backend/Gemfile.lock

@@ -73,6 +73,25 @@ GEM
       tzinfo (~> 2.0, >= 2.0.5)
       uri (>= 0.13.1)
     ast (2.4.3)
+    aws-eventstream (1.4.0)
+    aws-partitions (1.1231.0)
+    aws-sdk-core (3.244.0)
+      aws-eventstream (~> 1, >= 1.3.0)
+      aws-partitions (~> 1, >= 1.992.0)
+      aws-sigv4 (~> 1.9)
+      base64
+      bigdecimal
+      jmespath (~> 1, >= 1.6.1)
+      logger
+    aws-sdk-kms (1.123.0)
+      aws-sdk-core (~> 3, >= 3.244.0)
+      aws-sigv4 (~> 1.5)
+    aws-sdk-s3 (1.217.0)
+      aws-sdk-core (~> 3, >= 3.244.0)
+      aws-sdk-kms (~> 1)
+      aws-sigv4 (~> 1.5)
+    aws-sigv4 (1.12.1)
+      aws-eventstream (~> 1, >= 1.0.2)
     base64 (0.2.0)
     bcrypt_pbkdf (1.1.1)
     bcrypt_pbkdf (1.1.1-arm64-darwin)
@@ -157,6 +176,7 @@ GEM
       pp (>= 0.6.0)
       rdoc (>= 4.0.0)
       reline (>= 0.4.2)
+    jmespath (1.6.2)
     json (2.12.0)
     jwt (2.10.1)
       base64
@@ -441,6 +461,7 @@ PLATFORMS
   x86_64-linux-musl
 
 DEPENDENCIES
+  aws-sdk-s3
   bootsnap
   brakeman
   diff-lcs

backend/app/controllers/deerjikists_controller.rb

@@ -0,0 +1,47 @@
+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?
+
+    deerjikist = Deerjikist
+                 .joins(:tag)
+                 .includes(tag: :tag_name)
+                 .find_by(platform:, code:)
+    if deerjikist
+      render json: DeerjikistRepr.base(deerjikist)
+    else
+      head :not_found
+    end
+  end
+
+  def update
+    return head :unauthorized unless current_user
+    return head :forbidden unless current_user.gte_member?
+
+    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
+
+    deerjikist = Deerjikist.find_or_initialize_by(platform:, code:).tap do |d|
+      d.tag_id = tag_id
+      d.save!
+    end
+
+    render json: DeerjikistRepr.base(deerjikist)
+  end
+
+  def destroy
+    return head :unauthorized unless current_user
+    return head :forbidden unless current_user.gte_member?
+
+    platform = params[:platform].to_s.strip
+    code = params[:code].to_s.strip
+    return head :bad_request if platform.blank? || code.blank?
+
+    Deerjikist.find([platform, code]).destroy!
+
+    head :no_content
+  end
+end

backend/app/controllers/materials_controller.rb

@@ -0,0 +1,101 @@
+class MaterialsController < ApplicationController
+  def index
+    page = (params[:page].presence || 1).to_i
+    limit = (params[:limit].presence || 20).to_i
+
+    page = 1 if page < 1
+    limit = 1 if limit < 1
+
+    offset = (page - 1) * limit
+
+    tag_id = params[:tag_id].presence
+    parent_id = params[:parent_id].presence
+
+    q = Material.includes(:tag, :created_by_user).with_attached_file
+    q = q.where(tag_id:) if tag_id
+    q = q.where(parent_id:) if parent_id
+
+    count = q.count
+    materials = q.order(created_at: :desc, id: :desc).limit(limit).offset(offset)
+
+    render json: { materials: MaterialRepr.many(materials, host: request.base_url), count: count }
+  end
+
+  def show
+    material =
+        Material
+        .includes(:tag)
+        .with_attached_file
+        .find_by(id: params[:id])
+    return head :not_found unless material
+
+    wiki_page_body = material.tag.tag_name.wiki_page&.current_revision&.body
+
+    render json: MaterialRepr.base(material, host: request.base_url).merge(wiki_page_body:)
+  end
+
+  def create
+    return head :unauthorized unless current_user
+
+    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?)
+
+    tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
+    tag = tag_name.tag
+    tag = Tag.create!(tag_name:, category: :material) unless tag
+
+    material = Material.new(tag:, url:,
+                            created_by_user: current_user,
+                            updated_by_user: current_user)
+    material.file.attach(file)
+
+    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
+    end
+  end
+
+  def update
+    return head :unauthorized unless current_user
+    return head :forbidden unless current_user.gte_member?
+
+    material = Material.with_attached_file.find_by(id: params[:id])
+    return head :not_found unless material
+
+    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?)
+
+    tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
+    tag = tag_name.tag
+    tag = Tag.create!(tag_name:, category: :material) unless tag
+
+    material.update!(tag:, url:, updated_by_user: current_user)
+    if file
+      material.file.attach(file)
+    else
+      material.file.purge
+    end
+
+    if material.save
+      render json: MaterialRepr.base(material, host: request.base_url)
+    else
+      render json: { errors: material.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  def destroy
+    return head :unauthorized unless current_user
+    return head :forbidden unless current_user.gte_member?
+
+    material = Material.find_by(id: params[:id])
+    return head :not_found unless material
+
+    material.discard
+    head :no_content
+  end
+end

backend/app/controllers/nico_tags_controller.rb

@@ -1,16 +1,14 @@
 class NicoTagsController < ApplicationController
-  TAG_JSON = { only: [:id, :category, :post_count], methods: [:name, :has_wiki] }.freeze
-
   def index
     limit = (params[:limit] || 20).to_i
     cursor = params[:cursor].presence
 
     q = Tag.nico_tags
-           .includes(:tag_name, linked_tags: :tag_name)
+           .includes(:tag_name, tag_name: :wiki_page, linked_tags: { tag_name: :wiki_page })
            .order(updated_at: :desc)
     q = q.where('tags.updated_at < ?', Time.iso8601(cursor)) if cursor
 
-    tags = q.limit(limit + 1)
+    tags = q.limit(limit + 1).to_a
 
     next_cursor = nil
     if tags.size > limit
@@ -19,15 +17,15 @@ class NicoTagsController < ApplicationController
     end
 
     render json: { tags: tags.map { |tag|
-      tag.as_json(TAG_JSON).merge(linked_tags: tag.linked_tags.map { |lt|
-        lt.as_json(TAG_JSON)
+      TagRepr.base(tag).merge(linked_tags: tag.linked_tags.map { |lt|
+        TagRepr.base(lt)
       })
     }, next_cursor: }
   end
 
   def update
     return head :unauthorized unless current_user
-    return head :forbidden unless current_user.member?
+    return head :forbidden unless current_user.gte_member?
 
     id = params[:id].to_i
 
@@ -35,12 +33,13 @@ class NicoTagsController < ApplicationController
     return head :bad_request if tag.category != 'nico'
 
     linked_tag_names = params[:tags].to_s.split(' ')
-    linked_tags = Tag.normalise_tags(linked_tag_names, with_tagme: false)
+    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.category == 'nico' }
 
     tag.linked_tags = linked_tags
     tag.save!
 
-    render json: tag.linked_tags.map { |t| t.as_json(TAG_JSON) }, status: :ok
+    render json: tag.linked_tags.map { |t| TagRepr.base(t) }, status: :ok
   end
 end

backend/app/controllers/post_versions_controller.rb

@@ -0,0 +1,119 @@
+class PostVersionsController < ApplicationController
+  def index
+    post_id = params[:post].presence
+    tag_id = params[:tag].presence
+    page = (params[:page].presence || 1).to_i
+    limit = (params[:limit].presence || 20).to_i
+
+    page = 1 if page < 1
+    limit = 1 if limit < 1
+
+    offset = (page - 1) * limit
+
+    tag_name =
+        if tag_id
+          TagName.joins(:tag).find_by(tag: { id: tag_id })
+        end
+    return render json: { versions: [], count: 0 } if tag_id && tag_name.blank?
+
+    q = PostVersion.joins(<<~SQL.squish)
+          LEFT JOIN
+            post_versions prev
+            ON
+              prev.post_id = post_versions.post_id
+              AND prev.version_no = post_versions.version_no - 1
+        SQL
+        .select('post_versions.*', 'prev.title AS prev_title', 'prev.url AS prev_url',
+                'prev.thumbnail_base AS prev_thumbnail_base', 'prev.tags AS prev_tags',
+                'prev.original_created_from AS prev_original_created_from',
+                'prev.original_created_before AS prev_original_created_before')
+    q = q.where('post_versions.post_id = ?', post_id) if post_id
+    if tag_name
+      escaped = ActiveRecord::Base.sanitize_sql_like(tag_name.name)
+      q = q.where(("CONCAT(' ', post_versions.tags, ' ') LIKE :kw " +
+                   "OR CONCAT(' ', prev.tags, ' ') LIKE :kw"),
+                  kw: "% #{ escaped } %")
+    end
+
+    count = q.except(:select, :order, :limit, :offset).count
+
+    versions = q.order(Arel.sql('post_versions.created_at DESC, post_versions.id DESC'))
+                .limit(limit)
+                .offset(offset)
+
+    render json: { versions: serialise_versions(versions), count: }
+  end
+
+  private
+
+  def serialise_versions rows
+    user_ids = rows.map(&:created_by_user_id).compact.uniq
+    users_by_id = User.where(id: user_ids).pluck(:id, :name).to_h
+
+    rows.map do |row|
+      cur_tags = split_tags(row.tags)
+      prev_tags = split_tags(row.attributes['prev_tags'])
+
+      {
+        post_id: row.post_id,
+        version_no: row.version_no,
+        event_type: row.event_type,
+        title: {
+          current: row.title,
+          prev: row.attributes['prev_title']
+        },
+        url: {
+          current: row.url,
+          prev: row.attributes['prev_url']
+        },
+        thumbnail: {
+          current: nil,
+          prev: nil
+        },
+        thumbnail_base: {
+          current: row.thumbnail_base,
+          prev: row.attributes['prev_thumbnail_base']
+        },
+        tags: build_version_tags(cur_tags, prev_tags),
+        original_created_from: {
+          current: row.original_created_from&.iso8601,
+          prev: row.attributes['prev_original_created_from']&.iso8601
+        },
+        original_created_before: {
+          current: row.original_created_before&.iso8601,
+          prev: row.attributes['prev_original_created_before']&.iso8601
+        },
+        created_at: row.created_at.iso8601,
+        created_by_user:
+          if row.created_by_user_id
+            {
+              id: row.created_by_user_id,
+              name: users_by_id[row.created_by_user_id]
+            }
+          end
+      }
+    end
+  end
+
+  def build_version_tags(cur_tags, prev_tags)
+    (cur_tags | prev_tags).map do |name|
+      type =
+        if cur_tags.include?(name) && prev_tags.include?(name)
+          'context'
+        elsif cur_tags.include?(name)
+          'added'
+        else
+          'removed'
+        end
+
+      {
+        name:,
+        type:
+      }
+    end
+  end
+
+  def split_tags(tags)
+    tags.to_s.split(/\s+/).reject(&:blank?)
+  end
+end

backend/app/controllers/posts_controller.rb

@@ -2,41 +2,88 @@ class PostsController < ApplicationController
   Event = Struct.new(:post, :tag, :user, :change_type, :timestamp, keyword_init: true)
 
   def index
+    url = params[:url].presence
+    title = params[:title].presence
+    original_created_from = params[:original_created_from].presence
+    original_created_to = params[:original_created_to].presence
+    created_between = params[:created_from].presence, params[:created_to].presence
+    updated_between = params[:updated_from].presence, params[:updated_to].presence
+
+    order = params[:order].to_s.split(':', 2).map(&:strip)
+    unless order[0].in?(['title', 'url', 'original_created_at', 'created_at', 'updated_at'])
+      order[0] = 'original_created_at'
+    end
+    unless order[1].in?(['asc', 'desc'])
+      order[1] =
+          if order[0].in?(['title', 'url'])
+            'asc'
+          else
+            'desc'
+          end
+    end
+
     page = (params[:page].presence || 1).to_i
     limit = (params[:limit].presence || 20).to_i
-    cursor = params[:cursor].presence
 
     page = 1 if page < 1
     limit = 1 if limit < 1
 
     offset = (page - 1) * limit
 
-    sort_sql =
-        'COALESCE(posts.original_created_before - INTERVAL 1 SECOND,' +
-        'posts.original_created_from,' +
-        'posts.created_at)'
+    pt_max_sql =
+        PostTag
+        .select('post_id, MAX(updated_at) AS max_updated_at')
+        .group('post_id')
+        .to_sql
+
+    updated_at_all_sql =
+        'GREATEST(posts.updated_at,' +
+        'COALESCE(pt_max.max_updated_at, posts.updated_at))'
+
     q =
         filtered_posts
-        .preload(tags: :tag_name)
+        .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: [:materials, { tag_name: :wiki_page }])
         .with_attached_thumbnail
-        .select("posts.*, #{ sort_sql } AS sort_ts")
-        .order(Arel.sql("#{ sort_sql } DESC"))
-    posts = (
-        if cursor
-          q.where("#{ sort_sql } < ?", Time.iso8601(cursor)).limit(limit + 1)
-        else
-          q.limit(limit).offset(offset)
-        end).to_a
 
-    next_cursor = nil
-    if cursor && posts.length > limit
-      next_cursor = posts.last.read_attribute('sort_ts').iso8601(6)
-      posts = posts.first(limit)
+    q = q.where('posts.url LIKE ?', "%#{ url }%") if url
+    q = q.where('posts.title LIKE ?', "%#{ title }%") if title
+    if original_created_from
+      q = q.where('posts.original_created_before > ?', original_created_from)
+    end
+    if original_created_to
+      q = q.where('posts.original_created_from <= ?', original_created_to)
+    end
+    q = q.where('posts.created_at >= ?', created_between[0]) if created_between[0]
+    q = q.where('posts.created_at <= ?', created_between[1]) if created_between[1]
+    if updated_between[0]
+      q = q.where("#{ updated_at_all_sql } >= ?", updated_between[0])
+    end
+    if updated_between[1]
+      q = q.where("#{ updated_at_all_sql } <= ?", updated_between[1])
     end
 
+    sort_sql =
+        case order[0]
+        when 'original_created_at'
+          'COALESCE(posts.original_created_before - INTERVAL 1 MINUTE,' +
+          'posts.original_created_from,' +
+          'posts.created_at) '
+        when 'updated_at'
+          updated_at_all_sql
+        else
+          "posts.#{ order[0] }"
+        end
+    posts = q.order(Arel.sql("#{ sort_sql } #{ order[1] }, posts.id #{ order[1] }"))
+             .limit(limit)
+             .offset(offset)
+             .to_a
+
+    q = q.except(:select, :order)
+
     render json: { posts: posts.map { |post|
-      post.as_json(include: { tags: { only: [:id, :category, :post_count],
-                                      methods: [:name, :has_wiki] } }).tap do |json|
+      PostRepr.base(post).merge(updated_at: post.updated_at_all).tap do |json|
         json['thumbnail'] =
             if post.thumbnail.attached?
               rails_storage_proxy_url(post.thumbnail, only_path: false)
@@ -44,67 +91,56 @@ class PostsController < ApplicationController
               nil
             end
       end
-    }, count: if filtered_posts.group_values.present?
-      filtered_posts.count.size
-    else
-      filtered_posts.count
-    end, next_cursor: }
+    }, count: q.group_values.present? ? q.count.size : q.count }
   end
 
   def random
-    post = filtered_posts.preload(tags: :tag_name).order('RAND()').first
+    post = filtered_posts.preload(tags: [:materials, { tag_name: :wiki_page }])
+                         .order('RAND()')
+                         .first
     return head :not_found unless post
 
-    viewed = current_user&.viewed?(post) || false
-
-    render json: (post
-                  .as_json(include: { tags: { only: [:id, :category, :post_count],
-                                              methods: [:name, :has_wiki] } })
-                  .merge(viewed:))
+    render json: PostRepr.base(post, current_user)
   end
 
   def show
-    post = Post.includes(tags: :tag_name).find(params[:id])
+    post = Post.includes(tags: [:materials, { tag_name: :wiki_page }]).find_by(id: params[:id])
     return head :not_found unless post
 
-    viewed = current_user&.viewed?(post) || false
-
-    json = post.as_json
-    json['tags'] = build_tag_tree_for(post.tags)
-    json['related'] = post.related(limit: 20)
-    json['viewed'] = viewed
-
-    render json:
+    render json: PostRepr.base(post, current_user)
+                         .merge(tags: build_tag_tree_for(post.tags),
+                                related: post.related(limit: 20))
   end
 
   def create
     return head :unauthorized unless current_user
-    return head :forbidden unless current_user.member?
+    return head :forbidden unless current_user.gte_member?
 
     # TODO: サイトに応じて thumbnail_base 設定
     title = params[:title].presence
     url = params[:url]
     thumbnail = params[:thumbnail]
-    tag_names = params[:tags].to_s.split(' ')
+    tag_names = params[:tags].to_s.split
     original_created_from = params[:original_created_from]
     original_created_before = params[:original_created_before]
 
     post = Post.new(title:, url:, thumbnail_base: nil, uploaded_user: current_user,
                     original_created_from:, original_created_before:)
     post.thumbnail.attach(thumbnail)
-    if post.save
-      post.resized_thumbnail!
+
+    ActiveRecord::Base.transaction do
+      post.save!
       tags = Tag.normalise_tags(tag_names)
       tags = Tag.expand_parent_tags(tags)
       sync_post_tags!(post, tags)
+      post.resized_thumbnail!
+      PostVersionRecorder.record!(post:, event_type: :create, created_by_user: current_user)
+    end
 
     post.reload
-      render json: post.as_json(include: { tags: { only: [:id, :category, :post_count],
-                                                   methods: [:name, :has_wiki] } }),
-             status: :created
-    else
+    render json: PostRepr.base(post), status: :created
+  rescue ActiveRecord::RecordInvalid
     render json: { errors: post.errors.full_messages }, status: :unprocessable_entity
-    end
   rescue Tag::NicoTagNormalisationError
     head :bad_request
   end
@@ -125,33 +161,37 @@ class PostsController < ApplicationController
 
   def update
     return head :unauthorized unless current_user
-    return head :forbidden unless current_user.member?
+    return head :forbidden unless current_user.gte_member?
 
     title = params[:title].presence
-    tag_names = params[:tags].to_s.split(' ')
+    tag_names = params[:tags].to_s.split
     original_created_from = params[:original_created_from]
     original_created_before = params[:original_created_before]
 
     post = Post.find(params[:id].to_i)
-    if post.update(title:, original_created_from:, original_created_before:)
+
+    ActiveRecord::Base.transaction do
+      post.update!(title:, original_created_from:, original_created_before:)
       tags = post.tags.where(category: 'nico').to_a +
              Tag.normalise_tags(tag_names, with_tagme: false)
       tags = Tag.expand_parent_tags(tags)
       sync_post_tags!(post, tags)
+      PostVersionRecorder.record!(post:, event_type: :update, created_by_user: current_user)
+    end
 
     post.reload
     json = post.as_json
     json['tags'] = build_tag_tree_for(post.tags)
     render json:, status: :ok
-    else
+  rescue ActiveRecord::RecordInvalid
     render json: post.errors, status: :unprocessable_entity
-    end
   rescue Tag::NicoTagNormalisationError
     head :bad_request
   end
 
   def changes
-    id = params[:id]
+    id = params[:id].presence
+    tag_id = params[:tag].presence
     page = (params[:page].presence || 1).to_i
     limit = (params[:limit].presence || 20).to_i
 
@@ -162,21 +202,26 @@ class PostsController < ApplicationController
 
     pts = PostTag.with_discarded
     pts = pts.where(post_id: id) if id.present?
-    pts = pts.includes(:post, { tag: :tag_name }, :created_user, :deleted_user)
+    pts = pts.where(tag_id:) if tag_id.present?
+    pts = pts.includes(:post, :created_user, :deleted_user,
+                       tag: [:materials, { tag_name: :wiki_page }])
 
     events = []
     pts.each do |pt|
+      tag = TagRepr.base(pt.tag)
+      post = pt.post
+
       events << Event.new(
-          post:         pt.post,
-          tag:          pt.tag.as_json(only: [:id, :category], methods: [:name, :has_wiki]),
+          post:,
+          tag:,
           user: pt.created_user && { id: pt.created_user.id, name: pt.created_user.name },
           change_type: 'add',
           timestamp: pt.created_at)
 
       if pt.discarded_at
         events << Event.new(
-            post:         pt.post,
-            tag:          pt.tag.as_json(only: [:id, :category], methods: [:name, :has_wiki]),
+            post:,
+            tag:,
             user: pt.deleted_user && { id: pt.deleted_user.id, name: pt.deleted_user.name },
             change_type: 'remove',
             timestamp: pt.discarded_at)
@@ -185,13 +230,13 @@ class PostsController < ApplicationController
     events.sort_by!(&:timestamp)
     events.reverse!
 
-    render json: { changes: events.slice(offset, limit).as_json, count: events.size }
+    render json: { changes: (events.slice(offset, limit) || []).as_json, count: events.size }
   end
 
   private
 
   def filtered_posts
-    tag_names = params[:tags].to_s.split(' ')
+    tag_names = params[:tags].to_s.split
     match_type = params[:match]
     if tag_names.present?
       filter_posts_by_tags(tag_names, match_type)
@@ -201,18 +246,40 @@ class PostsController < ApplicationController
   end
 
   def filter_posts_by_tags tag_names, match_type
-    tag_names = TagName.canonicalise(tag_names)
+    literals = tag_names.map do |raw_name|
+      { name: TagName.canonicalise(raw_name.sub(/\Anot:/i, '')).first,
+        negative: raw_name.downcase.start_with?('not:') }
+    end
 
-    posts = Post.joins(tags: :tag_name)
+    return Post.all if literals.empty?
 
     if match_type == 'any'
-      posts.where(tag_names: { name: tag_names }).distinct
+      literals.reduce(Post.none) do |posts, literal|
+        posts.or(tag_literal_relation(literal[:name], negative: literal[:negative]))
+      end
     else
-      posts.where(tag_names: { name: tag_names })
-           .group('posts.id')
-           .having('COUNT(DISTINCT tag_names.id) = ?', tag_names.uniq.size)
+      literals.reduce(Post.all) do |posts, literal|
+        ids = tagged_post_ids_for(literal[:name])
+        if literal[:negative]
+          posts.where.not(id: ids)
+        else
+          posts.where(id: ids)
         end
       end
+    end
+  end
+
+  def tag_literal_relation name, negative:
+    ids = tagged_post_ids_for(name)
+    if negative
+      Post.where.not(id: ids)
+    else
+      Post.where(id: ids)
+    end
+  end
+
+  def tagged_post_ids_for(name) =
+      Post.joins(tags: :tag_name).where(tag_names: { name: }).select(:id)
 
   def sync_post_tags! post, desired_tags
     desired_tags.each do |t|
@@ -262,8 +329,7 @@ class PostsController < ApplicationController
       return nil unless tag
 
       if path.include?(tag_id)
-        return tag.as_json(only: [:id, :category, :post_count],
-                           methods: [:name, :has_wiki]).merge(children: [])
+        return TagRepr.base(tag).merge(children: [])
       end
 
       if memo.key?(tag_id)
@@ -275,8 +341,7 @@ class PostsController < ApplicationController
 
       children = child_ids.filter_map { |cid| build_node.(cid, new_path) }
 
-      memo[tag_id] = tag.as_json(only: [:id, :category, :post_count],
-                                 methods: [:name, :has_wiki]).merge(children:)
+      memo[tag_id] = TagRepr.base(tag).merge(children:)
     end
 
     root_ids.filter_map { |id| build_node.call(id, []) }

backend/app/controllers/tags_controller.rb

@@ -2,19 +2,113 @@ class TagsController < ApplicationController
   def index
     post_id = params[:post]
 
-    tags =
-        if post_id.present?
-          Tag.joins(:posts).where(posts: { id: post_id })
-        else
-          Tag.all
+    name = params[:name].presence
+    category = params[:category].presence
+    post_count_between = (params[:post_count_gte].presence || -1).to_i,
+                         (params[:post_count_lte].presence || -1).to_i
+    post_count_between[0] = nil if post_count_between[0] < 0
+    post_count_between[1] = nil if post_count_between[1] < 0
+    created_between = params[:created_from].presence, params[:created_to].presence
+    updated_between = params[:updated_from].presence, params[:updated_to].presence
+
+    order = params[:order].to_s.split(':', 2).map(&:strip)
+    unless order[0].in?(['name', 'category', 'post_count', 'created_at', 'updated_at'])
+      order[0] = 'post_count'
+    end
+    unless order[1].in?(['asc', 'desc'])
+      order[1] = order[0].in?(['name', 'category']) ? 'asc' : 'desc'
     end
 
-    render json: tags.as_json(only: [:id, :category, :post_count], methods: [:name, :has_wiki])
+    page = (params[:page].presence || 1).to_i
+    limit = (params[:limit].presence || 20).to_i
+
+    page = 1 if page < 1
+    limit = 1 if limit < 1
+
+    offset = (page - 1) * limit
+
+    q =
+        if post_id.present?
+          Tag.joins(:posts, :tag_name)
+        else
+          Tag.joins(:tag_name)
+        end
+        .includes(:tag_name, :materials, tag_name: :wiki_page)
+    q = q.where(posts: { id: post_id }) if post_id.present?
+
+    q = q.where('tag_names.name LIKE ?', "%#{ name }%") if name
+    q = q.where(category:) if category
+    q = q.where('tags.post_count >= ?', post_count_between[0]) if post_count_between[0]
+    q = q.where('tags.post_count <= ?', post_count_between[1]) if post_count_between[1]
+    q = q.where('tags.created_at >= ?', created_between[0]) if created_between[0]
+    q = q.where('tags.created_at <= ?', created_between[1]) if created_between[1]
+    q = q.where('tags.updated_at >= ?', updated_between[0]) if updated_between[0]
+    q = q.where('tags.updated_at <= ?', updated_between[1]) if updated_between[1]
+
+    sort_sql =
+        case order[0]
+        when 'name'
+          'tag_names.name'
+        when 'category'
+          'CASE tags.category ' +
+          "WHEN 'deerjikist' THEN 0 " +
+          "WHEN 'meme' THEN 1 " +
+          "WHEN 'character' THEN 2 " +
+          "WHEN 'general' THEN 3 " +
+          "WHEN 'material' THEN 4 " +
+          "WHEN 'meta' THEN 5 " +
+          "WHEN 'nico' THEN 6 END"
+        else
+          "tags.#{ order[0] }"
+        end
+    tags = q.order(Arel.sql("#{ sort_sql } #{ order[1] }, tags.id #{ order[1] }"))
+            .limit(limit)
+            .offset(offset)
+            .to_a
+
+    render json: { tags: TagRepr.base(tags), count: q.size }
+  end
+
+  def with_depth
+    parent_tag_id = params[:parent].to_i
+    parent_tag_id = nil if parent_tag_id <= 0
+
+    tag_ids =
+        if parent_tag_id
+          TagImplication.where(parent_tag_id:).select(:tag_id)
+        else
+          Tag.where.not(id: TagImplication.select(:tag_id)).select(:id)
+        end
+
+    tags =
+        Tag
+        .joins(:tag_name)
+        .includes(:tag_name, :materials, tag_name: :wiki_page)
+        .where(category: [:meme, :character, :material])
+        .where(id: tag_ids)
+        .order('tag_names.name')
+        .distinct
+        .to_a
+
+    has_children_tag_ids =
+        if tags.empty?
+          []
+        else
+          TagImplication
+              .joins(:tag)
+              .where(parent_tag_id: tags.map(&:id),
+                     tags: { category: [:meme, :character, :material] })
+              .distinct
+              .pluck(:parent_tag_id)
+        end
+
+    render json: tags.map { |tag|
+      TagRepr.base(tag).merge(has_children: has_children_tag_ids.include?(tag.id), children: [])
+    }
   end
 
   def autocomplete
-    q = params[:q].to_s.strip
-    return render json: [] if q.blank?
+    q = params[:q].to_s.strip.sub(/\Anot:/i, '')
 
     with_nico = bool?(:nico, default: true)
     present_only = bool?(:present, default: true)
@@ -33,7 +127,8 @@ class TagsController < ApplicationController
       matched_alias_by_tag_name_id[canonical_id] ||= alias_name
     end
 
-    base = Tag.joins(:tag_name).includes(:tag_name)
+    base = Tag.joins(:tag_name)
+              .includes(:tag_name, :materials, tag_name: :wiki_page)
     base = base.where('tags.post_count > 0') if present_only
 
     canonical_hit =
@@ -52,15 +147,16 @@ class TagsController < ApplicationController
     tags = tags.order(Arel.sql('post_count DESC, tag_names.name')).limit(20).to_a
 
     render json: tags.map { |tag|
-      tag.as_json(only: [:id, :category, :post_count], methods: [:name, :has_wiki])
-          .merge(matched_alias: matched_alias_by_tag_name_id[tag.tag_name_id])
+      TagRepr.base(tag).merge(matched_alias: matched_alias_by_tag_name_id[tag.tag_name_id])
     }
   end
 
   def show
-    tag = Tag.find_by(id: params[:id])
+    tag = Tag.joins(:tag_name)
+             .includes(:tag_name, :materials, tag_name: :wiki_page)
+             .find_by(id: params[:id])
     if tag
-      render json: tag.as_json(only: [:id, :category, :post_count], methods: [:name, :has_wiki])
+      render json: TagRepr.base(tag)
     else
       head :not_found
     end
@@ -70,17 +166,52 @@ class TagsController < ApplicationController
     name = params[:name].to_s.strip
     return head :bad_request if name.blank?
 
-    tag = Tag.joins(:tag_name).includes(:tag_name).find_by(tag_names: { name: })
+    tag = Tag.joins(:tag_name)
+             .includes(:tag_name, :materials, tag_name: :wiki_page)
+             .find_by(tag_names: { name: })
     if tag
-      render json: tag.as_json(only: [:id, :category, :post_count], methods: [:name, :has_wiki])
+      render json: TagRepr.base(tag)
     else
       head :not_found
     end
   end
 
+  def deerjikists
+    tag = Tag.joins(:tag_name)
+             .includes(:tag_name, tag_name: :wiki_page)
+             .find_by(id: params[:id])
+    return head :not_found unless tag
+
+    render json: DeerjikistRepr.many(tag.deerjikists)
+  end
+
+  def deerjikists_by_name
+    name = params[:name].to_s.strip
+    return head :bad_request if name.blank?
+
+    tag = Tag.joins(:tag_name)
+             .includes(:tag_name, tag_name: :wiki_page)
+             .find_by(tag_names: { name: })
+    return head :not_found unless tag
+
+    render json: DeerjikistRepr.many(tag.deerjikists)
+  end
+
+  def materials_by_name
+    name = params[:name].to_s.strip
+    return head :bad_request if name.blank?
+
+    tag = Tag.joins(:tag_name)
+             .includes(:tag_name, :materials, tag_name: :wiki_page)
+             .find_by(tag_names: { name: })
+    return head :not_found unless tag
+
+    render json: build_tag_children(tag)
+  end
+
   def update
     return head :unauthorized unless current_user
-    return head :forbidden unless current_user.member?
+    return head :forbidden unless current_user.gte_member?
 
     name = params[:name].presence
     category = params[:category].presence
@@ -95,6 +226,22 @@ class TagsController < ApplicationController
       tag.update!(category:)
     end
 
-    render json: tag.as_json(methods: [:name])
+    render json: TagRepr.base(tag)
+  end
+
+  private
+
+  def build_tag_children(tag)
+    material = tag.materials.first
+    file = nil
+    content_type = nil
+    if material&.file&.attached?
+      file = rails_storage_proxy_url(material.file, only_path: false)
+      content_type = material.file.blob.content_type
+    end
+
+    TagRepr.base(tag).merge(
+        children: tag.children.sort_by { _1.name }.map { build_tag_children(_1) },
+        material: material.as_json&.merge(file:, content_type:))
   end
 end

backend/app/controllers/theatre_comments_controller.rb

@@ -0,0 +1,32 @@
+class TheatreCommentsController < ApplicationController
+  def index
+    no_gt = params[:no_gt].to_i
+    no_gt = 0 if no_gt.negative?
+
+    comments = TheatreComment
+               .where(theatre_id: params[:theatre_id])
+               .where('no > ?', no_gt)
+               .order(no: :desc)
+
+    render json: comments.as_json(include: { user: { only: [:id, :name] } })
+  end
+
+  def create
+    return head :unauthorized unless current_user
+
+    content = params[:content]
+    return head :unprocessable_entity if content.blank?
+
+    theatre = Theatre.find_by(id: params[:theatre_id])
+    return head :not_found unless theatre
+
+    comment = nil
+    theatre.with_lock do
+      no = theatre.next_comment_no
+      comment = TheatreComment.create!(theatre:, no:, user: current_user, content:)
+      theatre.update!(next_comment_no: no + 1)
+    end
+
+    render json: comment, status: :created
+  end
+end

backend/app/controllers/theatres_controller.rb

@@ -0,0 +1,54 @@
+class TheatresController < ApplicationController
+  def show
+    theatre = Theatre.find_by(id: params[:id])
+    return head :not_found unless theatre
+
+    render json: TheatreRepr.base(theatre)
+  end
+
+  def watching
+    return head :unauthorized unless current_user
+
+    theatre = Theatre.find_by(id: params[:id])
+    return head :not_found unless theatre
+
+    host_flg = false
+    post_id = nil
+    post_started_at = nil
+
+    theatre.with_lock do
+      TheatreWatchingUser.find_or_initialize_by(theatre:, user: current_user).tap {
+        _1.expires_at = 30.seconds.from_now
+      }.save!
+
+      if (!(theatre.host_user_id?) ||
+          !(theatre.watching_users.exists?(id: theatre.host_user_id)))
+        theatre.update!(host_user_id: current_user.id)
+      end
+
+      host_flg = theatre.host_user_id == current_user.id
+      post_id = theatre.current_post_id
+      post_started_at = theatre.current_post_started_at
+    end
+
+    render json: {
+        host_flg:, post_id:, post_started_at:,
+        watching_users: theatre.watching_users.as_json(only: [:id, :name]) }
+  end
+
+  def next_post
+    return head :unauthorized unless current_user
+
+    theatre = Theatre.find_by(id: params[:id])
+    return head :not_found unless theatre
+    return head :forbidden if theatre.host_user != current_user
+
+    post = Post.where("url LIKE '%nicovideo.jp%'")
+           .or(Post.where("url LIKE '%youtube.com%'"))
+           .order('RAND()')
+           .first
+    theatre.update!(current_post: post, current_post_started_at: Time.current)
+
+    head :no_content
+  end
+end

backend/app/controllers/wiki_pages_controller.rb

@@ -3,15 +3,19 @@ class WikiPagesController < ApplicationController
 
   def index
     title = params[:title].to_s.strip
-    return render json: WikiPage.all.as_json(methods: [:title]) if title.blank?
+    if title.blank?
+      return render json: WikiPageRepr.base(WikiPage.joins(:tag_name).includes(:tag_name))
+    end
 
     q = WikiPage.joins(:tag_name).includes(:tag_name)
         .where('tag_names.name LIKE ?', "%#{ WikiPage.sanitize_sql_like(title) }%")
-    render json: q.limit(20).as_json(methods: [:title])
+    render json: WikiPageRepr.base(q.limit(20))
   end
 
   def show
-    page = WikiPage.find_by(id: params[:id])
+    page = WikiPage.joins(:tag_name)
+                   .includes(:tag_name)
+                   .find_by(id: params[:id])
     render_wiki_page_or_404 page
   end
 
@@ -19,7 +23,7 @@ class WikiPagesController < ApplicationController
     title = params[:title].to_s.strip
     page = WikiPage.joins(:tag_name)
                    .includes(:tag_name)
-                   .find_by(tag_names: { name: title })
+                   .find_by(tag_name: { name: title })
     render_wiki_page_or_404 page
   end
 
@@ -47,7 +51,7 @@ class WikiPagesController < ApplicationController
     from = params[:from].presence
     to = params[:to].presence
 
-    page = WikiPage.find(id)
+    page = WikiPage.joins(:tag_name).includes(:tag_name).find(id)
 
     from_rev = from && page.wiki_revisions.find(from)
     to_rev = to ? page.wiki_revisions.find(to) : page.current_revision
@@ -79,20 +83,20 @@ class WikiPagesController < ApplicationController
 
   def create
     return head :unauthorized unless current_user
-    return head :forbidden unless current_user.member?
+    return head :forbidden unless current_user.gte_member?
 
-    title = params[:title]&.strip
+    name = params[:title]&.strip
     body = params[:body].to_s
 
-    return head :unprocessable_entity if title.blank? || body.blank?
-
-    page = WikiPage.new(title:, created_user: current_user, updated_user: current_user)
+    return head :unprocessable_entity if name.blank? || body.blank?
 
+    tag_name = TagName.find_undiscard_or_create_by!(name:)
+    page = WikiPage.new(tag_name:, created_user: current_user, updated_user: current_user)
     if page.save
       message = params[:message].presence
       Wiki::Commit.content!(page:, body:, created_user: current_user, message:)
 
-      render json: page.as_json(methods: [:title]), status: :created
+      render json: WikiPageRepr.base(page), status: :created
     else
       render json: { errors: page.errors.full_messages },
              status: :unprocessable_entity
@@ -101,7 +105,7 @@ class WikiPagesController < ApplicationController
 
   def update
     return head :unauthorized unless current_user
-    return head :forbidden unless current_user.member?
+    return head :forbidden unless current_user.gte_member?
 
     title = params[:title]&.strip
     body = params[:body].to_s
@@ -131,7 +135,9 @@ class WikiPagesController < ApplicationController
 
   def changes
     id = params[:id].presence
-    q = WikiRevision.includes(:wiki_page, :created_user).order(id: :desc)
+    q = WikiRevision.joins(wiki_page: :tag_name)
+                    .includes(:created_user, wiki_page: :tag_name)
+                    .order(id: :desc)
     q = q.where(wiki_page_id: id) if id
 
     render json: q.limit(200).map { |rev|
@@ -139,7 +145,7 @@ class WikiPagesController < ApplicationController
         pred:         rev.base_revision_id,
         succ:         nil,
         wiki_page:    { id: rev.wiki_page_id, title: rev.wiki_page.title },
-        user:         { id: rev.created_user.id, name: rev.created_user.name },
+        user:         rev.created_user && { id: rev.created_user.id, name: rev.created_user.name },
         kind:         rev.kind,
         message:      rev.message,
         timestamp:    rev.created_at }
@@ -166,8 +172,7 @@ class WikiPagesController < ApplicationController
     succ = page.succ_revision_id(revision_id)
     updated_at = rev.created_at
 
-    render json: page.as_json(methods: [:title])
-                     .merge(body:, revision_id:, pred:, succ:, updated_at:)
+    render json: WikiPageRepr.base(page).merge(body:, revision_id:, pred:, succ:, updated_at:)
   end
 
   def find_revision page

backend/app/models/deerjikist.rb

@@ -0,0 +1,21 @@
+class Deerjikist < ApplicationRecord
+  self.primary_key = :platform, :code
+
+  belongs_to :tag
+
+  validates :platform, presence: true
+  validates :code, presence: true
+  validates :tag_id, presence: true
+
+  validate :tag_must_be_deerjikist
+
+  enum :platform, nico: 'nico', youtube: 'youtube'
+
+  private
+
+  def tag_must_be_deerjikist
+    if tag && !(tag.deerjikist?)
+      errors.add :tag, 'タグはニジラー・カテゴリである必要があります．'
+    end
+  end
+end

backend/app/models/material.rb

@@ -0,0 +1,39 @@
+class Material < ApplicationRecord
+  include MyDiscard
+
+  default_scope -> { kept }
+
+  belongs_to :parent, class_name: 'Material', optional: true
+  has_many :children, class_name: 'Material', foreign_key: :parent_id, dependent: :nullify
+
+  belongs_to :tag, optional: true
+  belongs_to :created_by_user, class_name: 'User', optional: true
+  belongs_to :updated_by_user, class_name: 'User', optional: true
+
+  has_one_attached :file, dependent: :purge
+
+  validates :tag_id, presence: true, uniqueness: true
+
+  validate :file_must_be_attached
+  validate :tag_must_be_material_category
+
+  def content_type
+    return nil unless file&.attached?
+
+    file.blob.content_type
+  end
+
+  private
+
+  def file_must_be_attached
+    return if url.present? || file.attached?
+
+    errors.add(:url, 'URL かファイルのどちらかは必須です．')
+  end
+
+  def tag_must_be_material_category
+    return if tag.blank? || tag.character? || tag.material?
+
+    errors.add(:tag, '素材カテゴリのタグを指定してください．')
+  end
+end

backend/app/models/my_discard.rb

@@ -0,0 +1,20 @@
+module MyDiscard
+  extend ActiveSupport::Concern
+
+  included { include Discard::Model }
+
+  class_methods do
+    def find_undiscard_or_create_by! attrs, &block
+      record = with_discarded.find_by(attrs)
+
+      if record&.discarded?
+        record.undiscard!
+        record.update_columns(created_at: record.reload.updated_at)
+      end
+
+      record or create!(attrs, &block)
+    rescue ActiveRecord::RecordNotUnique
+      retry
+    end
+  end
+end

backend/app/models/post.rb

@@ -11,6 +11,7 @@ class Post < ApplicationRecord
 
   has_many :user_post_views, dependent: :delete_all
   has_many :post_similarities, dependent: :delete_all
+  has_many :post_versions
 
   has_one_attached :thumbnail
 
@@ -30,13 +31,17 @@ class Post < ApplicationRecord
     super(options).merge(thumbnail: nil)
   end
 
-  def related(limit: nil)
-    ids = post_similarities.select(:target_post_id).order(cos: :desc)
+  def snapshot_tag_names = tags.joins(:tag_name).order('tag_names.name').pluck('tag_names.name')
+
+  def related limit: nil
+    ids = post_similarities.order(cos: :desc)
     ids = ids.limit(limit) if limit
     ids = ids.pluck(:target_post_id)
-    return [] if ids.empty?
+    return Post.none if ids.empty?
 
-    Post.where(id: ids).order(Arel.sql("FIELD(id, #{ ids.join(',') })"))
+    Post.where(id: ids)
+        .with_attached_thumbnail
+        .order(Arel.sql("FIELD(posts.id, #{ ids.join(',') })"))
   end
 
   def resized_thumbnail!

backend/app/models/post_version.rb

@@ -0,0 +1,38 @@
+class PostVersion < ApplicationRecord
+  before_update do
+    raise ActiveRecord::ReadOnlyRecord, '版は更新できません．'
+  end
+
+  before_destroy do
+    raise ActiveRecord::ReadOnlyRecord, '版は削除できません．'
+  end
+
+  belongs_to :post
+  belongs_to :parent, class_name: 'Post', optional: true
+  belongs_to :created_by_user, class_name: 'User', optional: true
+
+  enum :event_type, { create: 'create',
+                      update: 'update',
+                      discard: 'discard',
+                      restore: 'restore' }, prefix: true, validate: true
+
+  validates :version_no, presence: true, numericality: { only_integer: true, greater_than: 0 }
+  validates :event_type, presence: true, inclusion: { in: event_types.keys }
+  validates :url, presence: true
+
+  validate :validate_original_created_range
+
+  scope :chronological, -> { order(:version_no, :id) }
+
+  private
+
+  def validate_original_created_range
+    f = original_created_from
+    b = original_created_before
+    return if f.blank? || b.blank?
+
+    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．'
+    end
+  end
+end

backend/app/models/tag.rb

@@ -1,8 +1,15 @@
+require 'set'
+
+
 class Tag < ApplicationRecord
+  include MyDiscard
+
   class NicoTagNormalisationError < ArgumentError
     ;
   end
 
+  default_scope -> { kept }
+
   has_many :post_tags, inverse_of: :tag
   has_many :active_post_tags, -> { kept }, class_name: 'PostTag', inverse_of: :tag
   has_many :post_tags_with_discarded, -> { with_discarded }, class_name: 'PostTag'
@@ -23,8 +30,15 @@ class Tag < ApplicationRecord
   has_many :parents, through: :reversed_tag_implications, source: :parent_tag
 
   has_many :tag_similarities, dependent: :delete_all
+  has_many :tag_similarities_as_target,
+           class_name: 'TagSimilarity', foreign_key: :target_tag_id, dependent: :delete_all
+
+  has_many :deerjikists, dependent: :delete_all
+  has_many :materials
 
   belongs_to :tag_name
+  delegate :wiki_page, to: :tag_name
+
   delegate :name, to: :tag_name, allow_nil: true
   validates :tag_name, presence: true
 
@@ -40,14 +54,19 @@ class Tag < ApplicationRecord
 
   validate :nico_tag_name_must_start_with_nico
   validate :tag_name_must_be_canonical
+  validate :category_must_be_deerjikist_with_deerjikists
 
-  scope :nico_tags, -> { where(category: :nico) }
+  scope :nico_tags, -> { nico }
 
   CATEGORY_PREFIXES = {
+      'general:'    => :general,
       'gen:'        => :general,
+      'deerjikist:' => :deerjikist,
       'djk:'        => :deerjikist,
       'meme:'       => :meme,
+      'character:'  => :character,
       'chr:'        => :character,
+      'material:'   => :material,
       'mtr:'        => :material,
       'meta:'       => :meta }.freeze
 
@@ -55,9 +74,9 @@ class Tag < ApplicationRecord
     (self.tag_name ||= build_tag_name).name = val
   end
 
-  def has_wiki
-    tag_name&.wiki_page.present?
-  end
+  def has_wiki = wiki_page.present?
+
+  def material_id = materials.first&.id
 
   def self.tagme
     @tagme ||= find_or_create_by_tag_name!('タグ希望', category: :meta)
@@ -67,6 +86,10 @@ class Tag < ApplicationRecord
     @bot ||= find_or_create_by_tag_name!('bot操作', category: :meta)
   end
 
+  def self.no_deerjikist
+    @no_deerjikist ||= find_or_create_by_tag_name!('ニジラー情報不詳', category: :meta)
+  end
+
   def self.video
     @video ||= find_or_create_by_tag_name!('動画', category: :meta)
   end
@@ -75,22 +98,23 @@ class Tag < ApplicationRecord
     @niconico ||= find_or_create_by_tag_name!('ニコニコ', category: :meta)
   end
 
-  def self.normalise_tags tag_names, with_tagme: true, deny_nico: true
-    if deny_nico && tag_names.any? { |n| n.start_with?('nico:') }
+  def self.normalise_tags tag_names, with_tagme: true,
+                                     with_no_deerjikist: true,
+                                     deny_nico: true
+    if deny_nico && tag_names.any? { |n| n.downcase.start_with?('nico:') }
       raise NicoTagNormalisationError
     end
 
     tags = tag_names.map do |name|
-      pf, cat = CATEGORY_PREFIXES.find { |p, _| name.start_with?(p) } || ['', nil]
-      name = TagName.canonicalise(name.delete_prefix(pf)).first
+      pf, cat = CATEGORY_PREFIXES.find { |p, _| name.downcase.start_with?(p) } || ['', nil]
+      name = TagName.canonicalise(name.sub(/\A#{ pf }/i, '')).first
       find_or_create_by_tag_name!(name, category: (cat || :general)).tap do |tag|
-        if cat && tag.category != cat
-          tag.update!(category: cat)
-        end
+        tag.update!(category: cat) if cat && tag.category != cat
       end
     end
 
     tags << Tag.tagme if with_tagme && tags.size < 10 && tags.none?(Tag.tagme)
+    tags << Tag.no_deerjikist if with_no_deerjikist && tags.all? { |t| !(t.deerjikist?) }
     tags.uniq(&:id)
   end
 
@@ -118,22 +142,69 @@ class Tag < ApplicationRecord
   end
 
   def self.find_or_create_by_tag_name! name, category:
-    tn = TagName.find_or_create_by!(name: name.to_s.strip)
+    tn = TagName.find_undiscard_or_create_by!(name: name.to_s.strip)
     tn = tn.canonical if tn.canonical_id?
 
-    Tag.find_or_create_by!(tag_name_id: tn.id) do |t|
+    Tag.find_undiscard_or_create_by!(tag_name_id: tn.id) do |t|
       t.category = category
     end
   rescue ActiveRecord::RecordNotUnique
     retry
   end
 
+  def self.merge_tags! target_tag, source_tags
+    target_tag => Tag
+
+    affected_post_ids = Set.new
+
+    Tag.transaction do
+      Array(source_tags).compact.uniq.each do |source_tag|
+        source_tag => Tag
+
+        next if source_tag == target_tag
+
+        source_tag.post_tags.kept.find_each do |source_pt|
+          post_id = source_pt.post_id
+          affected_post_ids << post_id
+          source_pt.discard_by!(nil)
+          unless PostTag.kept.exists?(post_id:, tag: target_tag)
+            PostTag.create!(post_id:, tag: target_tag)
+          end
+        end
+
+        source_tag_name = source_tag.tag_name
+
+        if source_tag_name.wiki_page.present?
+          raise ActiveRecord::RecordInvalid.new(source_tag_name)
+        end
+
+        source_tag.discard!
+
+        if source_tag.nico?
+          source_tag_name.discard!
+        else
+          source_tag_name.update_columns(canonical_id: target_tag.tag_name_id,
+                                         updated_at: Time.current)
+        end
+      end
+
+      Post.where(id: affected_post_ids.to_a).find_each do |post|
+        PostVersionRecorder.record!(post:, event_type: :update, created_by_user: nil)
+      end
+
+      # 投稿件数を再集計
+      target_tag.update_columns(post_count: PostTag.kept.where(tag: target_tag).count)
+    end
+
+    target_tag.reload
+  end
+
   private
 
   def nico_tag_name_must_start_with_nico
     n = name.to_s
-    if ((category == 'nico' && !(n.start_with?('nico:'))) || 
-        (category != 'nico' && n.start_with?('nico:')))
+    if ((nico? && !(n.downcase.start_with?('nico:'))) || 
+        (!(nico?) && n.downcase.start_with?('nico:')))
       errors.add :name, 'ニコニコ・タグの命名規則に反してゐます．'
     end
   end
@@ -143,4 +214,10 @@ class Tag < ApplicationRecord
       errors.add :tag_name, 'tag_names へは実体を示す必要があります．'
     end
   end
+
+  def category_must_be_deerjikist_with_deerjikists
+    if !(deerjikist?) && deerjikists.exists?
+      errors.add :category, 'ニジラーと紐づいてゐるタグはニジラー・カテゴリである必要があります．'
+    end
+  end
 end

backend/app/models/tag_name.rb

@@ -1,4 +1,8 @@
 class TagName < ApplicationRecord
+  include MyDiscard
+
+  default_scope -> { kept }
+
   has_one :tag
   has_one :wiki_page
 
@@ -10,6 +14,7 @@ class TagName < ApplicationRecord
   validate :canonical_must_be_canonical
   validate :alias_name_must_not_have_prefix
   validate :canonical_must_not_be_present_with_tag_or_wiki_page
+  validate :name_must_be_sanitised
 
   def self.canonicalise names
     names = Array(names).map { |n| n.to_s.strip }.reject(&:blank?)
@@ -39,4 +44,10 @@ class TagName < ApplicationRecord
       errors.add :canonical, 'タグもしくは Wiki の参照がある名前はエーリアスになれません．'
     end
   end
+
+  def name_must_be_sanitised
+    if name? && name != TagNameSanitisationRule.sanitise(name)
+      errors.add :name, '名前に使用できない文字が含まれてゐます．'
+    end
+  end
 end

backend/app/models/tag_name_sanitisation_rule.rb

@@ -0,0 +1,58 @@
+class TagNameSanitisationRule < ApplicationRecord
+  include Discard::Model
+
+  self.primary_key = :priority
+
+  default_scope -> { kept }
+
+  validates :source_pattern, presence: true, uniqueness: true
+
+  validate :source_pattern_must_be_regexp
+
+  class << self
+    def sanitise(name) =
+        rules.reduce(name.dup) { |name, (pattern, replacement)| name.gsub(pattern, replacement) }
+
+    def apply!
+      TagName.find_each do |tn|
+        name = sanitise(tn.name)
+        next if name == tn.name
+
+        TagName.transaction do
+          existing_tn = TagName.find_by(name:)
+          if existing_tn
+            existing_tn = existing_tn.canonical || existing_tn
+            next if existing_tn.id == tn.id
+
+            existing_tag = Tag.find_by(tag_name_id: existing_tn.id)
+            source_tag = Tag.find_by(tag_name_id: tn.id)
+
+            if existing_tag
+              Tag.merge_tags!(existing_tag, source_tag) if tn.tag
+            elsif source_tag
+              source_tag.update_columns(tag_name_id: existing_tn.id, updated_at: Time.current)
+            end
+            tn.discard!
+
+            next
+          end
+
+          # TagName 側の自動サニタイズを回避
+          tn.update_columns(name:, updated_at: Time.current)
+        end
+      end
+    end
+
+    private
+
+    def rules = kept.order(:priority).map { |r| [Regexp.new(r.source_pattern), r.replacement] }
+  end
+
+  private
+
+  def source_pattern_must_be_regexp
+    Regexp.new(source_pattern)
+  rescue RegexpError
+    errors.add :source_pattern, '変な正規表現だね〜（笑）'
+  end
+end

backend/app/models/theatre.rb

@@ -0,0 +1,13 @@
+class Theatre < ApplicationRecord
+  include MyDiscard
+
+  has_many :comments, class_name: 'TheatreComment'
+  has_many :theatre_watching_users, dependent: :delete_all
+  has_many :active_theatre_watching_users, -> { active },
+           class_name: 'TheatreWatchingUser', inverse_of: :theatre
+  has_many :watching_users, through: :active_theatre_watching_users, source: :user
+
+  belongs_to :host_user, class_name: 'User', optional: true
+  belongs_to :current_post, class_name: 'Post', optional: true
+  belongs_to :created_by_user, class_name: 'User'
+end

backend/app/models/theatre_comment.rb

@@ -0,0 +1,8 @@
+class TheatreComment < ApplicationRecord
+  include Discard::Model
+
+  self.primary_key = :theatre_id, :no
+
+  belongs_to :theatre
+  belongs_to :user
+end

backend/app/models/theatre_watching_user.rb

@@ -0,0 +1,13 @@
+class TheatreWatchingUser < ApplicationRecord
+  self.primary_key = :theatre_id, :user_id
+
+  belongs_to :theatre
+  belongs_to :user
+
+  scope :active, -> { where('expires_at >= ?', Time.current) }
+  scope :expired, -> { where('expires_at < ?', Time.current) }
+
+  def active? = expires_at >= Time.current
+
+  def refresh! = update!(expires_at: 30.seconds.from_now)
+end

backend/app/models/user.rb

@@ -1,29 +1,23 @@
 class User < ApplicationRecord
-  enum :role, { guest: 'guest', member: 'member', admin: 'admin' }
+  enum :role, guest: 'guest', member: 'member', admin: 'admin'
 
   validates :name, length: { maximum: 255 }
   validates :inheritance_code, presence: true, length: { maximum: 64 }
   validates :role, presence: true, inclusion: { in: roles.keys }
   validates :banned, inclusion: { in: [true, false] }
 
-  has_many :posts
+  has_many :created_posts,
+           class_name: 'Post', foreign_key: :uploaded_user_id, dependent: :nullify
   has_many :settings
   has_many :user_ips, dependent: :destroy
   has_many :ip_addresses, through: :user_ips
   has_many :user_post_views, dependent: :destroy
   has_many :viewed_posts, through: :user_post_views, source: :post
-  has_many :created_wiki_pages, class_name: 'WikiPage', foreign_key: 'created_user_id', dependent: :nullify
-  has_many :updated_wiki_pages, class_name: 'WikiPage', foreign_key: 'updated_user_id', dependent: :nullify
+  has_many :created_wiki_pages,
+           class_name: 'WikiPage', foreign_key: :created_user_id, dependent: :nullify
+  has_many :updated_wiki_pages,
+           class_name: 'WikiPage', foreign_key: :updated_user_id, dependent: :nullify
 
-  def viewed? post
-    user_post_views.exists? post_id: post.id
-  end
-
-  def member?
-    ['member', 'admin'].include?(role)
-  end
-
-  def admin?
-    role == 'admin'
-  end
+  def viewed?(post) = user_post_views.exists?(post_id: post.id)
+  def gte_member? = member? || admin?
 end

backend/app/models/wiki_line.rb

@@ -8,7 +8,7 @@ class WikiLine < ApplicationRecord
     sha = Digest::SHA256.hexdigest(body)
     now = Time.current
 
-    upsert({ sha256: sha, body:, created_at: now, updated_at: now })
+    upsert(sha256: sha, body:, created_at: now, updated_at: now)
 
     find_by!(sha256: sha)
   end

backend/app/models/wiki_page.rb

@@ -2,6 +2,10 @@ require 'set'
 
 
 class WikiPage < ApplicationRecord
+  include MyDiscard
+
+  default_scope -> { kept }
+
   has_many :wiki_revisions, dependent: :destroy
   belongs_to :created_user, class_name: 'User'
   belongs_to :updated_user, class_name: 'User'
@@ -14,17 +18,13 @@ class WikiPage < ApplicationRecord
   belongs_to :tag_name
   validates :tag_name, presence: true
 
-  def title
-    tag_name.name
-  end
+  def title = tag_name.name
 
   def title= val
     (self.tag_name ||= build_tag_name).name = val
   end
 
-  def current_revision
-    wiki_revisions.order(id: :desc).first
-  end
+  def current_revision = wiki_revisions.order(id: :desc).first
 
   def body
     rev = current_revision
@@ -49,11 +49,8 @@ class WikiPage < ApplicationRecord
     page
   end
 
-  def pred_revision_id revision_id
+  def pred_revision_id(revision_id) =
       wiki_revisions.where('id < ?', revision_id).order(id: :desc).limit(1).pick(:id)
-  end
-
-  def succ_revision_id revision_id
+  def succ_revision_id(revision_id) =
       wiki_revisions.where('id > ?', revision_id).order(id: :asc).limit(1).pick(:id)
-  end
 end

backend/app/models/wiki_revision.rb

@@ -7,7 +7,7 @@ class WikiRevision < ApplicationRecord
   has_many :wiki_revision_lines, dependent: :delete_all
   has_many :wiki_lines, through: :wiki_revision_lines
 
-  enum :kind, { content: 0, redirect: 1 }
+  enum :kind, content: 0, redirect: 1
 
   validates :kind, presence: true
   validates :lines_count, numericality: { only_integer: true, greater_than_or_equal_to: 0 }

backend/app/representations/deerjikist_repr.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+
+module DeerjikistRepr
+  BASE = { only: [:platform, :code], include: { tag: TagRepr::BASE } }.freeze
+
+  module_function
+
+  def base deerjikist
+    deerjikist.as_json(BASE)
+  end
+
+  def many deerjikists
+    deerjikists.map { |d| base(d) }
+  end
+end

backend/app/representations/material_repr.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+
+module MaterialRepr
+  BASE = { only: [:id, :url, :created_at, :updated_at],
+           methods: [:content_type],
+           include: { tag: TagRepr::BASE,
+                      created_by_user: UserRepr::BASE,
+                      updated_by_user: UserRepr::BASE } }.freeze
+
+  module_function
+
+  def base material, host:
+    material.as_json(BASE).merge(
+        file: if material.file.attached?
+                Rails.application.routes.url_helpers.rails_storage_proxy_url(
+                    material.file, host:)
+              end)
+  end
+
+  def many materials, host:
+    materials.map { |m| base(m, host:) }
+  end
+end

backend/app/representations/post_repr.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+
+module PostRepr
+  BASE = { include: { tags: TagRepr::BASE, uploaded_user: UserRepr::BASE } }.freeze
+
+  module_function
+
+  def base post, current_user = nil
+    json = post.as_json(BASE)
+    return json.merge(viewed: false) unless current_user
+
+    viewed = current_user.viewed?(post)
+    json.merge(viewed:)
+  end
+
+  def many posts, current_user = nil
+    posts.map { |p| base(p, current_user) }
+  end
+end

backend/app/representations/tag_repr.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+
+module TagRepr
+  BASE = { only: [:id, :category, :post_count, :created_at, :updated_at],
+           methods: [:name, :has_wiki, :material_id] }.freeze
+
+  module_function
+
+  def base tag
+    tag.as_json(BASE)
+  end
+
+  def many tags
+    tags.map { |t| base(t) }
+  end
+end

backend/app/representations/theatre_repr.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+
+module TheatreRepr
+  BASE = { only: [:id, :name, :opens_at, :closes_at, :created_at, :updated_at],
+           include: { created_by_user: { only: [:id, :name] } } }.freeze
+
+  module_function
+
+  def base theatre
+    theatre.as_json(BASE)
+  end
+
+  def many theatre
+    theatre.map { |t| base(t) }
+  end
+end

backend/app/representations/user_repr.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+
+module UserRepr
+  BASE = { only: [:id, :name] }.freeze
+
+  module_function
+
+  def base user
+    user.as_json(BASE)
+  end
+
+  def many users
+    users.map { |u| base(u) }
+  end
+end

backend/app/representations/wiki_page_repr.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+
+module WikiPageRepr
+  BASE = { methods: [:title] }.freeze
+
+  module_function
+
+  def base wiki_page
+    wiki_page.as_json(BASE)
+  end
+
+  def many wiki_pages
+    wiki_pages.map { |p| base(p) }
+  end
+end

backend/app/services/post_version_recorder.rb

@@ -0,0 +1,57 @@
+class PostVersionRecorder
+  def self.record! post:, event_type:, created_by_user:
+    new(post:, event_type:, created_by_user:).record!
+  end
+
+  def initialize post:, event_type:, created_by_user:
+    @post = post
+    @event_type = event_type
+    @created_by_user = created_by_user
+  end
+
+  def record!
+    @post.with_lock do
+      latest = @post.post_versions.order(version_no: :desc).first
+      attrs = snapshot_attributes
+
+      return latest if @event_type == :update && latest && same_snapshot?(latest, attrs)
+
+      PostVersion.create!(
+          post: @post,
+          version_no: (latest&.version_no || 0) + 1,
+          event_type: @event_type,
+          title: attrs[:title],
+          url: attrs[:url],
+          thumbnail_base: attrs[:thumbnail_base],
+          tags: attrs[:tags],
+          parent: attrs[:parent],
+          original_created_from: attrs[:original_created_from],
+          original_created_before: attrs[:original_created_before],
+          created_at: Time.current,
+          created_by_user: @created_by_user)
+    end
+  end
+
+  private
+
+  def snapshot_attributes
+    { title: @post.title,
+      url: @post.url,
+      thumbnail_base: @post.thumbnail_base,
+      tags: @post.snapshot_tag_names.join(' '),
+      parent: @post.parent,
+      original_created_from: @post.original_created_from,
+      original_created_before: @post.original_created_before }
+  end
+
+  def same_snapshot? version, attrs
+    true &&
+        version.title == attrs[:title] &&
+        version.url == attrs[:url] &&
+        version.thumbnail_base == attrs[:thumbnail_base] &&
+        version.tags == attrs[:tags] &&
+        version.parent_id == attrs[:parent]&.id &&
+        version.original_created_from == attrs[:original_created_from] &&
+        version.original_created_before == attrs[:original_created_before]
+  end
+end

backend/config/environments/production.rb

@@ -18,8 +18,7 @@ Rails.application.configure do
   # Enable serving of images, stylesheets, and JavaScripts from an asset server.
   # config.asset_host = "http://assets.example.com"
 
-  # Store uploaded files on the local file system (see config/storage.yml for options).
-  config.active_storage.service = :local
+  config.active_storage.service = :r2
 
   # Assume all access to the app is happening through a SSL-terminating reverse proxy.
   config.assume_ssl = true

backend/config/environments/test.rb

@@ -50,4 +50,6 @@ Rails.application.configure do
 
   # Raise error when a before_action's only/except options reference missing actions.
   config.action_controller.raise_on_missing_callback_actions = true
+
+  Rails.application.routes.default_url_options[:host] = 'www.example.com'
 end

backend/config/routes.rb

@@ -9,7 +9,17 @@ Rails.application.routes.draw do
   resources :tags, only: [:index, :show, :update] do
     collection do
       get :autocomplete
-      get 'name/:name', action: :show_by_name
+      get :'with-depth', action: :with_depth
+
+      scope :name do
+        get ':name/deerjikists', action: :deerjikists_by_name
+        get ':name/materials', action: :materials_by_name
+        get ':name', action: :show_by_name
+      end
+    end
+
+    member do
+      get :deerjikists
     end
   end
 
@@ -39,6 +49,7 @@ Rails.application.routes.draw do
     collection do
       get :random
       get :changes
+      get :versions, to: 'post_versions#index'
     end
 
     member do
@@ -54,4 +65,25 @@ Rails.application.routes.draw do
       post 'code/renew', action: :renew
     end
   end
+
+  resources :deerjikists, only: [] do
+    collection do
+      scope ':platform/:code' do
+        get '', action: :show
+        put '', action: :update
+        delete '', action: :destroy
+      end
+    end
+  end
+
+  resources :theatres, only: [:show] do
+    member do
+      put :watching
+      patch :next_post
+    end
+
+    resources :comments, controller: :theatre_comments, only: [:index, :create]
+  end
+
+  resources :materials, only: [:index, :show, :create, :update, :destroy]
 end

backend/config/storage.yml

@@ -6,29 +6,11 @@ local:
   service: Disk
   root: <%= Rails.root.join("storage") %>
 
-# Use bin/rails credentials:edit to set the AWS secrets (as aws:access_key_id|secret_access_key)
-# amazon:
-#   service: S3
-#   access_key_id: <%= Rails.application.credentials.dig(:aws, :access_key_id) %>
-#   secret_access_key: <%= Rails.application.credentials.dig(:aws, :secret_access_key) %>
-#   region: us-east-1
-#   bucket: your_own_bucket-<%= Rails.env %>
-
-# Remember not to checkin your GCS keyfile to a repository
-# google:
-#   service: GCS
-#   project: your_project
-#   credentials: <%= Rails.root.join("path/to/gcs.keyfile") %>
-#   bucket: your_own_bucket-<%= Rails.env %>
-
-# Use bin/rails credentials:edit to set the Azure Storage secret (as azure_storage:storage_access_key)
-# microsoft:
-#   service: AzureStorage
-#   storage_account_name: your_account_name
-#   storage_access_key: <%= Rails.application.credentials.dig(:azure_storage, :storage_access_key) %>
-#   container: your_container_name-<%= Rails.env %>
-
-# mirror:
-#   service: Mirror
-#   primary: local
-#   mirrors: [ amazon, google, microsoft ]
+r2:
+  service: S3
+  endpoint: <%= ENV['R2_ENDPOINT'] %>
+  access_key_id: <%= ENV['R2_ACCESS_KEY_ID'] %>
+  secret_access_key: <%= ENV['R2_SECRET_ACCESS_KEY'] %>
+  bucket: <%= ENV['R2_BUCKET'] %>
+  region: auto
+  request_checksum_calculation: when_required

backend/db/migrate/20260303122700_create_deerjikists.rb

@@ -0,0 +1,10 @@
+class CreateDeerjikists < ActiveRecord::Migration[8.0]
+  def change
+    create_table :deerjikists, primary_key: [:platform, :code] do |t|
+      t.string :platform, null: false, limit: 16
+      t.string :code, null: false
+      t.references :tag, null: false
+      t.timestamps
+    end
+  end
+end

backend/db/migrate/20260309123200_create_tag_name_sanitisation_rules.rb

@@ -0,0 +1,31 @@
+class CreateTagNameSanitisationRules < ActiveRecord::Migration[8.0]
+  def up
+    create_table :tag_name_sanitisation_rules, id: :integer, primary_key: :priority do |t|
+      t.string :source_pattern, null: false
+      t.string :replacement, null: false
+      t.timestamps
+      t.datetime :discarded_at
+      t.index :source_pattern, unique: true
+      t.index :discarded_at
+    end
+
+    now = ActiveRecord::Base.connection.quote(Time.current)
+    execute <<~SQL
+      INSERT INTO
+        tag_name_sanitisation_rules(priority, source_pattern, replacement, created_at, updated_at)
+      VALUES
+        (10, '\\\\*',           '_',         #{ now }, #{ now })
+      , (20, '\\\\?',           '_',         #{ now }, #{ now })
+      , (25, '\\\\/',           '_',         #{ now }, #{ now })
+      , (30, '_+',              '_',         #{ now }, #{ now })
+      , (40, '_$',              '',          #{ now }, #{ now })
+      , (45, '^([^:]+\\\\:)?_', '\\\\1',     #{ now }, #{ now })
+      , (50, '^([^:]+\\\\:)?$', '\\\\1null', #{ now }, #{ now })
+      ;
+    SQL
+  end
+
+  def down
+    drop_table :tag_name_sanitisation_rules
+  end
+end

backend/db/migrate/20260311123100_add_discarded_at_to_tags.rb

@@ -0,0 +1,6 @@
+class AddDiscardedAtToTags < ActiveRecord::Migration[8.0]
+  def change
+    add_column :tags, :discarded_at, :datetime
+    add_index :tags, :discarded_at
+  end
+end

backend/db/migrate/20260311232100_add_discarded_at_to_tag_names.rb

@@ -0,0 +1,6 @@
+class AddDiscardedAtToTagNames < ActiveRecord::Migration[8.0]
+  def change
+    add_column :tag_names, :discarded_at, :datetime
+    add_index :tag_names, :discarded_at
+  end
+end

backend/db/migrate/20260311232300_add_discarded_at_to_wiki_pages.rb

@@ -0,0 +1,6 @@
+class AddDiscardedAtToWikiPages < ActiveRecord::Migration[8.0]
+  def change
+    add_column :wiki_pages, :discarded_at, :datetime
+    add_index :wiki_pages, :discarded_at
+  end
+end

backend/db/migrate/20260316082500_create_theatres.rb

@@ -0,0 +1,17 @@
+class CreateTheatres < ActiveRecord::Migration[8.0]
+  def change
+    create_table :theatres do |t|
+      t.string :name
+      t.datetime :opens_at, null: false, index: true
+      t.datetime :closes_at, index: true
+      t.integer :kind, null: false, index: true
+      t.references :current_post, foreign_key: { to_table: :posts }, index: true
+      t.datetime :current_post_started_at
+      t.integer :next_comment_no, null: false, default: 1
+      t.references :host_user, foreign_key: { to_table: :users }
+      t.references :created_by_user, null: false, foreign_key: { to_table: :users }, index: true
+      t.timestamps
+      t.datetime :discarded_at, index: true
+    end
+  end
+end

backend/db/migrate/20260316083500_create_theatre_comments.rb

@@ -0,0 +1,12 @@
+class CreateTheatreComments < ActiveRecord::Migration[8.0]
+  def change
+    create_table :theatre_comments, primary_key: [:theatre_id, :no] do |t|
+      t.references :theatre, null: false, foreign_key: { to_table: :theatres }
+      t.integer :no, null: false
+      t.references :user, foreign_key: { to_table: :users }
+      t.text :content, null: false
+      t.timestamps
+      t.datetime :discarded_at, index: true
+    end
+  end
+end

backend/db/migrate/20260317015000_create_theatre_watching_users.rb

@@ -0,0 +1,12 @@
+class CreateTheatreWatchingUsers < ActiveRecord::Migration[8.0]
+  def change
+    create_table :theatre_watching_users, primary_key: [:theatre_id, :user_id] do |t|
+      t.references :theatre, null: false, foreign_key: { to_table: :theatres }
+      t.references :user, null: false, foreign_key: { to_table: :users }, index: true
+      t.datetime :expires_at, null: false, index: true
+      t.timestamps
+
+      t.index [:theatre_id, :expires_at]
+    end
+  end
+end

backend/db/migrate/20260329034700_create_materials.rb

@@ -0,0 +1,34 @@
+class CreateMaterials < ActiveRecord::Migration[8.0]
+  def change
+    create_table :materials do |t|
+      t.string :url
+      t.references :parent, index: true, foreign_key: { to_table: :materials }
+      t.references :tag, index: true, foreign_key: true
+      t.references :created_by_user, foreign_key: { to_table: :users }
+      t.references :updated_by_user, foreign_key: { to_table: :users }
+      t.timestamps
+      t.datetime :discarded_at, index: true
+      t.virtual :active_url, type: :string,
+                             as: 'IF(discarded_at IS NULL, url, NULL)',
+                             stored: false
+
+      t.index :active_url, unique: true
+    end
+
+    create_table :material_versions do |t|
+      t.references :material, null: false, foreign_key: true
+      t.integer :version_no, null: false
+      t.string :url, index: true
+      t.references :parent, index: true, foreign_key: { to_table: :materials }
+      t.references :tag, index: true, foreign_key: true
+      t.references :created_by_user, foreign_key: { to_table: :users }
+      t.references :updated_by_user, foreign_key: { to_table: :users }
+      t.timestamps
+      t.datetime :discarded_at, index: true
+
+      t.index [:material_id, :version_no],
+              unique: true,
+              name: 'index_material_versions_on_material_id_and_version_no'
+    end
+  end
+end

backend/db/migrate/20260409123700_create_post_versions.rb

@@ -0,0 +1,203 @@
+require 'set'
+
+
+class CreatePostVersions < ActiveRecord::Migration[8.0]
+  class Post < ApplicationRecord
+    self.table_name = 'posts'
+  end
+
+  class PostTag < ApplicationRecord
+    self.table_name = 'post_tags'
+  end
+
+  class PostVersion < ApplicationRecord
+    self.table_name = 'post_versions'
+  end
+
+  def up
+    create_table :post_versions do |t|
+      t.references :post, null: false, foreign_key: true
+      t.integer :version_no, null: false
+      t.string :event_type, null: false
+      t.string :title
+      t.string :url, limit: 768, null: false
+      t.string :thumbnail_base, limit: 2000
+      t.text :tags, null: false
+      t.references :parent, foreign_key: { to_table: :posts }
+      t.datetime :original_created_from
+      t.datetime :original_created_before
+      t.datetime :created_at, null: false
+      t.references :created_by_user, foreign_key: { to_table: :users }
+
+      t.index [:post_id, :version_no], unique: true
+      t.check_constraint 'version_no > 0',
+                         name: 'post_versions_version_no_positive'
+      t.check_constraint "event_type IN ('create', 'update', 'discard', 'restore')",
+                         name: 'post_versions_event_type_valid'
+    end
+
+    PostVersion.reset_column_information
+
+    say_with_time 'Backfilling post_versions' do
+      Post.find_in_batches(batch_size: 500) do |posts|
+        post_ids = posts.map(&:id)
+
+        post_tag_rows_by_post_id =
+            PostTag
+            .joins('INNER JOIN tags ON tags.id = post_tags.tag_id')
+            .joins('INNER JOIN tag_names ON tag_names.id = tags.tag_name_id')
+            .where(post_id: post_ids)
+            .pluck('post_tags.post_id',
+                   'post_tags.created_at',
+                   'post_tags.discarded_at',
+                   'post_tags.created_user_id',
+                   'post_tags.deleted_user_id',
+                   'tag_names.name')
+            .each_with_object(Hash.new { |h, k| h[k] = [] }) do |row, h|
+              post_id, created_at, discarded_at, created_user_id, deleted_user_id, tag_name = row
+              h[post_id] << { created_at:,
+                              discarded_at:,
+                              created_user_id:,
+                              deleted_user_id:,
+                              tag_name: }
+            end
+
+        rows = []
+
+        posts.each do |post|
+          post_tag_rows = post_tag_rows_by_post_id[post.id]
+
+          events = post_tag_rows.flat_map do |post_tag_row|
+            ary = [[post_tag_row[:created_at],
+                    post_tag_row[:created_user_id],
+                    :add,
+                    post_tag_row[:tag_name]]]
+
+            if post_tag_row[:discarded_at]
+              ary << [post_tag_row[:discarded_at],
+                      post_tag_row[:deleted_user_id],
+                      :remove,
+                      post_tag_row[:tag_name]]
+            end
+
+            ary
+          end
+
+          kind_order = { add: 0, remove: 1 }
+
+          events.sort_by! do |event_at, user_id, kind, tag_name|
+            [event_at, user_id || 0, kind_order.fetch(kind), tag_name]
+          end
+
+          event_buckets = bucket_events(events)
+
+          active_tags = Set.new
+          version_no = 0
+
+          if event_buckets.empty?
+            version_no += 1
+            rows << build_row(post:,
+                              version_no:,
+                              event_type: 'create',
+                              created_at: post.created_at,
+                              created_by_user_id: post.uploaded_user_id,
+                              tags: [])
+            next
+          end
+
+          first_bucket = event_buckets.first
+          merge_first_bucket_into_create = first_bucket[:first_at] <= post.created_at + 1.second
+
+          if merge_first_bucket_into_create
+            event_buckets.shift
+            apply_bucket!(active_tags, first_bucket)
+
+            version_no += 1
+            rows << build_row(
+                post:,
+                version_no:,
+                event_type: 'create',
+                created_at: post.created_at,
+                created_by_user_id: post.uploaded_user_id || first_bucket[:user_ids].compact.first,
+                tags: active_tags.to_a.sort)
+          else
+            version_no += 1
+            rows << build_row(
+                post:,
+                version_no:,
+                event_type: 'create',
+                created_at: post.created_at,
+                created_by_user_id: post.uploaded_user_id,
+                tags: [])
+          end
+
+          event_buckets.each do |bucket|
+            apply_bucket!(active_tags, bucket)
+
+            version_no += 1
+            rows << build_row(
+                post:,
+                version_no:,
+                event_type: 'update',
+                created_at: bucket[:first_at],
+                created_by_user_id: bucket[:user_ids].compact.first,
+                tags: active_tags.to_a.sort)
+          end
+        end
+
+        PostVersion.insert_all!(rows) if rows.any?
+      end
+    end
+  end
+
+  def down
+    drop_table :post_versions
+  end
+
+  private
+
+  def bucket_events events
+    buckets = []
+
+    events.each do |event_at, user_id, kind, tag_name|
+      if buckets.empty? || event_at - buckets.last[:last_at] > 1.second
+        buckets << { first_at: event_at,
+                     last_at: event_at,
+                     user_ids: [user_id],
+                     events: [[kind, tag_name]] }
+      else
+        bucket = buckets.last
+        bucket[:last_at] = event_at
+        bucket[:user_ids] << user_id
+        bucket[:events] << [kind, tag_name]
+      end
+    end
+
+    buckets
+  end
+
+  def apply_bucket! active_tags, bucket
+    bucket[:events].each do |kind, tag_name|
+      if kind == :add
+        active_tags.add(tag_name)
+      else
+        active_tags.delete(tag_name)
+      end
+    end
+  end
+
+  def build_row post:, version_no:, event_type:, created_at:, created_by_user_id:, tags:
+    { post_id: post.id,
+      version_no:,
+      event_type:,
+      title: post.title,
+      url: post.url,
+      thumbnail_base: post.thumbnail_base,
+      tags: tags.join(' '),
+      parent_id: post.parent_id,
+      original_created_from: post.original_created_from,
+      original_created_before: post.original_created_before,
+      created_at:,
+      created_by_user_id: }
+  end
+end

backend/db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
+ActiveRecord::Schema[8.0].define(version: 2026_04_09_123700) do
   create_table "active_storage_attachments", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -39,6 +39,15 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
     t.index ["blob_id", "variation_digest"], name: "index_active_storage_variant_records_uniqueness", unique: true
   end
 
+  create_table "deerjikists", primary_key: ["platform", "code"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "platform", limit: 16, null: false
+    t.string "code", null: false
+    t.bigint "tag_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["tag_id"], name: "index_deerjikists_on_tag_id"
+  end
+
   create_table "ip_addresses", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.binary "ip_address", limit: 16, null: false
     t.boolean "banned", default: false, null: false
@@ -47,6 +56,45 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
     t.index ["ip_address"], name: "index_ip_addresses_on_ip_address", unique: true
   end
 
+  create_table "material_versions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "material_id", null: false
+    t.integer "version_no", null: false
+    t.string "url"
+    t.bigint "parent_id"
+    t.bigint "tag_id"
+    t.bigint "created_by_user_id"
+    t.bigint "updated_by_user_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.datetime "discarded_at"
+    t.index ["created_by_user_id"], name: "index_material_versions_on_created_by_user_id"
+    t.index ["discarded_at"], name: "index_material_versions_on_discarded_at"
+    t.index ["material_id", "version_no"], name: "index_material_versions_on_material_id_and_version_no", unique: true
+    t.index ["material_id"], name: "index_material_versions_on_material_id"
+    t.index ["parent_id"], name: "index_material_versions_on_parent_id"
+    t.index ["tag_id"], name: "index_material_versions_on_tag_id"
+    t.index ["updated_by_user_id"], name: "index_material_versions_on_updated_by_user_id"
+    t.index ["url"], name: "index_material_versions_on_url"
+  end
+
+  create_table "materials", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "url"
+    t.bigint "parent_id"
+    t.bigint "tag_id"
+    t.bigint "created_by_user_id"
+    t.bigint "updated_by_user_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.datetime "discarded_at"
+    t.virtual "active_url", type: :string, as: "if((`discarded_at` is null),`url`,NULL)"
+    t.index ["active_url"], name: "index_materials_on_active_url", unique: true
+    t.index ["created_by_user_id"], name: "index_materials_on_created_by_user_id"
+    t.index ["discarded_at"], name: "index_materials_on_discarded_at"
+    t.index ["parent_id"], name: "index_materials_on_parent_id"
+    t.index ["tag_id"], name: "index_materials_on_tag_id"
+    t.index ["updated_by_user_id"], name: "index_materials_on_updated_by_user_id"
+  end
+
   create_table "nico_tag_relations", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "nico_tag_id", null: false
     t.bigint "tag_id", null: false
@@ -84,6 +132,27 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
     t.index ["tag_id"], name: "index_post_tags_on_tag_id"
   end
 
+  create_table "post_versions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "post_id", null: false
+    t.integer "version_no", null: false
+    t.string "event_type", null: false
+    t.string "title"
+    t.string "url", limit: 768, null: false
+    t.string "thumbnail_base", limit: 2000
+    t.text "tags", null: false
+    t.bigint "parent_id"
+    t.datetime "original_created_from"
+    t.datetime "original_created_before"
+    t.datetime "created_at", null: false
+    t.bigint "created_by_user_id"
+    t.index ["created_by_user_id"], name: "index_post_versions_on_created_by_user_id"
+    t.index ["parent_id"], name: "index_post_versions_on_parent_id"
+    t.index ["post_id", "version_no"], name: "index_post_versions_on_post_id_and_version_no", unique: true
+    t.index ["post_id"], name: "index_post_versions_on_post_id"
+    t.check_constraint "`event_type` in (_utf8mb4'create',_utf8mb4'update',_utf8mb4'discard',_utf8mb4'restore')", name: "post_versions_event_type_valid"
+    t.check_constraint "`version_no` > 0", name: "post_versions_version_no_positive"
+  end
+
   create_table "posts", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "title"
     t.string "url", limit: 768, null: false
@@ -118,12 +187,24 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
     t.index ["tag_id"], name: "index_tag_implications_on_tag_id"
   end
 
+  create_table "tag_name_sanitisation_rules", primary_key: "priority", id: :integer, charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "source_pattern", null: false
+    t.string "replacement", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.datetime "discarded_at"
+    t.index ["discarded_at"], name: "index_tag_name_sanitisation_rules_on_discarded_at"
+    t.index ["source_pattern"], name: "index_tag_name_sanitisation_rules_on_source_pattern", unique: true
+  end
+
   create_table "tag_names", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "name", null: false
     t.bigint "canonical_id"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.datetime "discarded_at"
     t.index ["canonical_id"], name: "index_tag_names_on_canonical_id"
+    t.index ["discarded_at"], name: "index_tag_names_on_discarded_at"
     t.index ["name"], name: "index_tag_names_on_name", unique: true
   end
 
@@ -141,9 +222,58 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.integer "post_count", default: 0, null: false
+    t.datetime "discarded_at"
+    t.index ["discarded_at"], name: "index_tags_on_discarded_at"
     t.index ["tag_name_id"], name: "index_tags_on_tag_name_id", unique: true
   end
 
+  create_table "theatre_comments", primary_key: ["theatre_id", "no"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "theatre_id", null: false
+    t.integer "no", null: false
+    t.bigint "user_id"
+    t.text "content", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.datetime "discarded_at"
+    t.index ["discarded_at"], name: "index_theatre_comments_on_discarded_at"
+    t.index ["theatre_id"], name: "index_theatre_comments_on_theatre_id"
+    t.index ["user_id"], name: "index_theatre_comments_on_user_id"
+  end
+
+  create_table "theatre_watching_users", primary_key: ["theatre_id", "user_id"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "theatre_id", null: false
+    t.bigint "user_id", null: false
+    t.datetime "expires_at", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["expires_at"], name: "index_theatre_watching_users_on_expires_at"
+    t.index ["theatre_id", "expires_at"], name: "index_theatre_watching_users_on_theatre_id_and_expires_at"
+    t.index ["theatre_id"], name: "index_theatre_watching_users_on_theatre_id"
+    t.index ["user_id"], name: "index_theatre_watching_users_on_user_id"
+  end
+
+  create_table "theatres", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "name"
+    t.datetime "opens_at", null: false
+    t.datetime "closes_at"
+    t.integer "kind", null: false
+    t.bigint "current_post_id"
+    t.datetime "current_post_started_at"
+    t.integer "next_comment_no", default: 1, null: false
+    t.bigint "host_user_id"
+    t.bigint "created_by_user_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.datetime "discarded_at"
+    t.index ["closes_at"], name: "index_theatres_on_closes_at"
+    t.index ["created_by_user_id"], name: "index_theatres_on_created_by_user_id"
+    t.index ["current_post_id"], name: "index_theatres_on_current_post_id"
+    t.index ["discarded_at"], name: "index_theatres_on_discarded_at"
+    t.index ["host_user_id"], name: "index_theatres_on_host_user_id"
+    t.index ["kind"], name: "index_theatres_on_kind"
+    t.index ["opens_at"], name: "index_theatres_on_opens_at"
+  end
+
   create_table "user_ips", primary_key: ["user_id", "ip_address_id"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "user_id", null: false
     t.bigint "ip_address_id", null: false
@@ -169,6 +299,19 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
     t.datetime "updated_at", null: false
   end
 
+  create_table "wiki_assets", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "wiki_page_id", null: false
+    t.integer "no", null: false
+    t.string "alt_text"
+    t.binary "sha256", limit: 32, null: false
+    t.bigint "created_by_user_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["created_by_user_id"], name: "index_wiki_assets_on_created_by_user_id"
+    t.index ["wiki_page_id", "no"], name: "index_wiki_assets_on_wiki_page_id_and_no", unique: true
+    t.index ["wiki_page_id", "sha256"], name: "index_wiki_assets_on_wiki_page_id_and_sha256", unique: true
+  end
+
   create_table "wiki_lines", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "sha256", limit: 64, null: false
     t.text "body", null: false
@@ -183,7 +326,10 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
     t.bigint "updated_user_id", null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.datetime "discarded_at"
+    t.integer "next_asset_no", default: 1, null: false
     t.index ["created_user_id"], name: "index_wiki_pages_on_created_user_id"
+    t.index ["discarded_at"], name: "index_wiki_pages_on_discarded_at"
     t.index ["tag_name_id"], name: "index_wiki_pages_on_tag_name_id", unique: true
     t.index ["updated_user_id"], name: "index_wiki_pages_on_updated_user_id"
   end
@@ -220,6 +366,15 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
 
   add_foreign_key "active_storage_attachments", "active_storage_blobs", column: "blob_id"
   add_foreign_key "active_storage_variant_records", "active_storage_blobs", column: "blob_id"
+  add_foreign_key "material_versions", "materials"
+  add_foreign_key "material_versions", "materials", column: "parent_id"
+  add_foreign_key "material_versions", "tags"
+  add_foreign_key "material_versions", "users", column: "created_by_user_id"
+  add_foreign_key "material_versions", "users", column: "updated_by_user_id"
+  add_foreign_key "materials", "materials", column: "parent_id"
+  add_foreign_key "materials", "tags"
+  add_foreign_key "materials", "users", column: "created_by_user_id"
+  add_foreign_key "materials", "users", column: "updated_by_user_id"
   add_foreign_key "nico_tag_relations", "tags"
   add_foreign_key "nico_tag_relations", "tags", column: "nico_tag_id"
   add_foreign_key "post_similarities", "posts"
@@ -228,6 +383,9 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
   add_foreign_key "post_tags", "tags"
   add_foreign_key "post_tags", "users", column: "created_user_id"
   add_foreign_key "post_tags", "users", column: "deleted_user_id"
+  add_foreign_key "post_versions", "posts"
+  add_foreign_key "post_versions", "posts", column: "parent_id"
+  add_foreign_key "post_versions", "users", column: "created_by_user_id"
   add_foreign_key "posts", "posts", column: "parent_id"
   add_foreign_key "posts", "users", column: "uploaded_user_id"
   add_foreign_key "settings", "users"
@@ -237,10 +395,19 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_27_005300) do
   add_foreign_key "tag_similarities", "tags"
   add_foreign_key "tag_similarities", "tags", column: "target_tag_id"
   add_foreign_key "tags", "tag_names"
+  add_foreign_key "theatre_comments", "theatres"
+  add_foreign_key "theatre_comments", "users"
+  add_foreign_key "theatre_watching_users", "theatres"
+  add_foreign_key "theatre_watching_users", "users"
+  add_foreign_key "theatres", "posts", column: "current_post_id"
+  add_foreign_key "theatres", "users", column: "created_by_user_id"
+  add_foreign_key "theatres", "users", column: "host_user_id"
   add_foreign_key "user_ips", "ip_addresses"
   add_foreign_key "user_ips", "users"
   add_foreign_key "user_post_views", "posts"
   add_foreign_key "user_post_views", "users"
+  add_foreign_key "wiki_assets", "users", column: "created_by_user_id"
+  add_foreign_key "wiki_assets", "wiki_pages"
   add_foreign_key "wiki_pages", "tag_names"
   add_foreign_key "wiki_pages", "users", column: "created_user_id"
   add_foreign_key "wiki_pages", "users", column: "updated_user_id"

backend/lib/tasks/sync_nico.rake

@@ -2,9 +2,9 @@ namespace :nico do
   desc 'ニコニコ DB 同期'
   task sync: :environment do
     require 'json'
-    require 'open3'
-    require 'open-uri'
     require 'nokogiri'
+    require 'open-uri'
+    require 'open3'
     require 'set'
     require 'time'
 
@@ -15,12 +15,12 @@ namespace :nico do
       doc.at('meta[name="thumbnail"]')&.[]('content').presence
     end
 
-    def sync_post_tags! post, desired_tag_ids, current_ids: nil
-      current_ids ||= PostTag.kept.where(post_id: post.id).pluck(:tag_id).to_set
-      desired_ids = desired_tag_ids.compact.to_set
+    def sync_post_tags! post, desired_tag_ids, current_tag_ids: nil
+      current_tag_ids ||= PostTag.kept.where(post_id: post.id).pluck(:tag_id).to_set
+      desired_tag_ids = desired_tag_ids.compact.to_set
 
-      to_add = desired_ids - current_ids
-      to_remove = current_ids - desired_ids
+      to_add = desired_tag_ids - current_tag_ids
+      to_remove = current_tag_ids - desired_tag_ids
 
       Tag.where(id: to_add.to_a).find_each do |tag|
         begin
@@ -42,12 +42,14 @@ namespace :nico do
         { 'MYSQL_USER' => mysql_user, 'MYSQL_PASS' => mysql_pass },
         'python3', "#{ nizika_nico_path }/get_videos.py")
 
-    abort unless status.success?
+    unless status.success?
+      warn stderr
+      abort
+    end
 
     data = JSON.parse(stdout)
     data.each do |datum|
       code = datum['code']
-
       post =
           Post
           .where('url REGEXP ?', "nicovideo\\.jp/watch/#{ Regexp.escape(code) }([^0-9]|$)")
@@ -59,6 +61,9 @@ namespace :nico do
       original_created_from = original_created_at&.change(sec: 0)
       original_created_before = original_created_from&.+(1.minute)
 
+      post_created = false
+      post_changed = false
+
       if post
         attrs = { title:, original_created_from:, original_created_before: }
 
@@ -74,11 +79,13 @@ namespace :nico do
         end
 
         post.assign_attributes(attrs)
-        if post.changed?
+        post_changed = post.changed?
+        if post_changed
           post.save!
           post.resized_thumbnail! if post.thumbnail.attached?
         end
       else
+        post_created = true
         url = "https://www.nicovideo.jp/watch/#{ code }"
         thumbnail_base = fetch_thumbnail.(url) rescue nil
         post = Post.new(title:, url:, thumbnail_base:, uploaded_user: nil,
@@ -94,32 +101,56 @@ namespace :nico do
         sync_post_tags!(post, [Tag.tagme.id, Tag.bot.id, Tag.niconico.id, Tag.video.id])
       end
 
-      kept_ids = PostTag.kept.where(post_id: post.id).pluck(:tag_id).to_set
-      kept_non_nico_ids = post.tags.where.not(category: 'nico').pluck(:id).to_set
+      tags = post.tags
+      # 既存のタグ Id. 集合
+      kept_tag_ids = tags.pluck(:id).to_set
+      # うち内部タグ Id. 集合
+      kept_non_nico_tag_ids = tags.not_nico.pluck(:id).to_set
+
+      # 記載すべき外部タグ Id. および連携される内部タグ Id. のリスト
+      desired_nico_tag_based_ids = []
+      # 記載すべき内部タグ Id. のリスト
+      desired_non_nico_tag_ids = []
 
-      desired_nico_ids = []
-      desired_non_nico_ids = []
       datum['tags'].each do |raw|
-        name = "nico:#{ raw }"
-        tag = Tag.find_or_create_by_tag_name!(name, category: 'nico')
-        desired_nico_ids << tag.id
-        unless tag.id.in?(kept_ids)
+        name = TagNameSanitisationRule.sanitise("nico:#{ raw }")
+        tag = Tag.find_or_create_by_tag_name!(name, category: :nico)
+        desired_nico_tag_based_ids << tag.id
+
+        # 新たに記載される外部タグと連携される内部タグを記載
+        unless tag.id.in?(kept_tag_ids)
           linked_ids = tag.linked_tags.pluck(:id)
-          desired_non_nico_ids.concat(linked_ids)
-          desired_nico_ids.concat(linked_ids)
+          desired_non_nico_tag_ids.concat(linked_ids)
+          desired_nico_tag_based_ids.concat(linked_ids)
         end
       end
-      desired_nico_ids.uniq!
 
-      desired_all_ids = kept_non_nico_ids.to_a + desired_nico_ids
-      desired_non_nico_ids.concat(kept_non_nico_ids.to_a)
-      desired_non_nico_ids.uniq!
-      if kept_non_nico_ids.to_set != desired_non_nico_ids.to_set
-        desired_all_ids << Tag.bot.id
+      deerjikist = Deerjikist.find_by(platform: :nico, code: datum['user'])
+      if deerjikist
+        desired_non_nico_tag_ids << deerjikist.tag_id
+        desired_nico_tag_based_ids << deerjikist.tag_id
+      elsif !(Tag.where(id: kept_non_nico_tag_ids).where(category: :deerjikist).exists?)
+        desired_non_nico_tag_ids << Tag.no_deerjikist.id
+        desired_nico_tag_based_ids << Tag.no_deerjikist.id
       end
-      desired_all_ids.uniq!
 
-      sync_post_tags!(post, desired_all_ids, current_ids: kept_ids)
+      desired_nico_tag_based_ids.uniq!
+
+      desired_all_tag_ids = kept_non_nico_tag_ids.to_a + desired_nico_tag_based_ids
+      desired_non_nico_tag_ids.concat(kept_non_nico_tag_ids.to_a)
+      desired_non_nico_tag_ids.uniq!
+      if kept_non_nico_tag_ids != desired_non_nico_tag_ids.to_set
+        desired_all_tag_ids << Tag.bot.id
+      end
+      desired_all_tag_ids.uniq!
+
+      sync_post_tags!(post, desired_all_tag_ids, current_tag_ids: kept_tag_ids)
+
+      if post_created
+        PostVersionRecorder.record!(post:, event_type: :create, created_by_user: nil)
+      elsif post_changed || kept_tag_ids != desired_all_tag_ids.to_set
+        PostVersionRecorder.record!(post:, event_type: :update, created_by_user: nil)
+      end
     end
   end
 end

backend/spec/factories/tags.rb

@@ -1,12 +1,22 @@
 FactoryBot.define do
   factory :tag do
-    category { 'general' }
+    transient do
+      name { nil }
+    end
+
+    category { :general }
     post_count { 0 }
     association :tag_name
 
+    after(:build) do |tag, evaluator|
+      tag.name = evaluator.name if evaluator.name.present?
+    end
+
     trait :nico do
-      category { 'nico' }
-      tag_name { association(:tag_name, name: "nico:#{ SecureRandom.hex(4) }") }
+      category { :nico }
+      transient do
+        name { "nico:#{ SecureRandom.hex(4) }" }
+      end
     end
   end
 end

backend/spec/factories/theatre_comments.rb

@@ -0,0 +1,8 @@
+FactoryBot.define do
+  factory :theatre_comment do
+    association :theatre
+    association :user
+    sequence (:no) { |n| n }
+    content { 'test comment' }
+  end
+end

backend/spec/factories/theatres.rb

@@ -0,0 +1,11 @@
+FactoryBot.define do
+  factory :theatre do
+    name { 'Test Theatre' }
+    kind { 1 }
+    opens_at { Time.current }
+    closes_at { 1.day.from_now }
+    next_comment_no { 1 }
+
+    association :created_by_user, factory: :user
+  end
+end

backend/spec/models/post_version_spec.rb

@@ -0,0 +1,41 @@
+require 'rails_helper'
+
+RSpec.describe PostVersion, type: :model do
+  let!(:tag_name) { TagName.create!(name: 'post_version_spec_tag') }
+  let!(:tag) { Tag.create!(tag_name: tag_name, category: :general) }
+
+  let!(:post_record) do
+    Post.create!(title: 'spec post', url: 'https://example.com/post-version-spec').tap do |post|
+      PostTag.create!(post: post, tag: tag)
+    end
+  end
+
+  let!(:post_version) do
+    PostVersion.create!(
+      post: post_record,
+      version_no: 1,
+      event_type: 'create',
+      title: post_record.title,
+      url: post_record.url,
+      thumbnail_base: post_record.thumbnail_base,
+      tags: post_record.snapshot_tag_names.join(' '),
+      parent: post_record.parent,
+      original_created_from: post_record.original_created_from,
+      original_created_before: post_record.original_created_before,
+      created_at: Time.current,
+      created_by_user: nil
+    )
+  end
+
+  it 'is read only after create' do
+    expect do
+      post_version.update!(title: 'changed')
+    end.to raise_error(ActiveRecord::ReadOnlyRecord)
+  end
+
+  it 'cannot be destroyed' do
+    expect do
+      post_version.destroy!
+    end.to raise_error(ActiveRecord::ReadOnlyRecord)
+  end
+end

backend/spec/models/tag_name_sanitisation_rule_spec.rb

@@ -0,0 +1,101 @@
+require 'rails_helper'
+
+RSpec.describe TagNameSanitisationRule, type: :model do
+  describe '.sanitise' do
+    before do
+      described_class.create!(priority: 10, source_pattern: '_', replacement: '')
+      described_class.create!(priority: 20, source_pattern: 'ABC', replacement: 'abc')
+    end
+
+    it 'applies sanitisation rules sequentially in priority order' do
+      expect(described_class.sanitise('A_B_C')).to eq('abc')
+    end
+
+    it 'does not fail when a rule does not match' do
+      expect { described_class.sanitise('xyz') }.not_to raise_error
+      expect(described_class.sanitise('xyz')).to eq('xyz')
+    end
+  end
+
+  describe 'validations' do
+    it 'is invalid when source_pattern is not a valid regexp' do
+      rule = described_class.new(priority: 10, source_pattern: '[', replacement: '')
+      expect(rule).to be_invalid
+      expect(rule.errors[:source_pattern]).to be_present
+    end
+  end
+
+  describe '.apply!' do
+    before do
+      described_class.create!(priority: 10, source_pattern: '_', replacement: '')
+    end
+
+    context 'when no conflicting tag_name exists' do
+      let!(:tag_name) do
+        TagName.create!(name: 'tmp').tap do |tn|
+          tn.update_columns(name: 'foo_bar', updated_at: Time.current)
+        end
+      end
+
+      it 'renames the tag_name' do
+        described_class.apply!
+        expect(tag_name.reload.name).to eq('foobar')
+      end
+    end
+
+    context 'when a conflicting canonical tag_name exists' do
+      let!(:existing) { TagName.create!(name: 'foobar') }
+      let!(:source) do
+        TagName.create!(name: 'tmp').tap do |tn|
+          tn.update_columns(name: 'foo_bar', updated_at: Time.current)
+        end
+      end
+
+      it 'deletes the source tag_name' do
+        described_class.apply!
+        expect(TagName.exists?(source.id)).to be(false)
+        expect(existing.reload.name).to eq('foobar')
+      end
+    end
+
+    context 'when the source tag_name has a tag and the existing one has no tag' do
+      let!(:existing) { TagName.create!(name: 'foobar') }
+      let!(:source_tag) { create(:tag, name: 'tmp', category: :general) }
+      let!(:source_tag_name_id) { source_tag.tag_name_id }
+
+      before do
+        source_tag.tag_name.update_columns(name: 'foo_bar', updated_at: Time.current)
+      end
+
+      it 'moves the tag to the existing tag_name' do
+        described_class.apply!
+        expected_tag_name_id = existing.canonical_id || existing.id
+        expect(source_tag.reload.tag_name_id).to eq(expected_tag_name_id)
+        expect(TagName.exists?(source_tag_name_id)).to be(false)
+      end
+    end
+
+    context 'when both source and existing tag_names have tags' do
+      let!(:existing_tn) { TagName.create!(name: 'foobar') }
+      let!(:existing_tag) { Tag.create!(tag_name: existing_tn, category: :general) }
+
+      let!(:source_tn) { TagName.create!(name: 'tmp') }
+      let!(:source_tag) { Tag.create!(tag_name: source_tn, category: :general) }
+      let!(:source_tag_name_id) { source_tn.id }
+
+      before do
+        source_tn.update_columns(name: 'foo_bar', updated_at: Time.current)
+      end
+
+      it 'merges the source tag into the existing tag and deletes the source tag_name' do
+        expect(TagName.find_by(name: 'foobar')&.tag&.id).to eq(existing_tag.id)
+        expect(TagName.find_by(name: 'foo_bar')&.tag&.id).to eq(source_tag.id)
+
+        described_class.apply!
+
+        expect(Tag.exists?(source_tag.id)).to be(false)
+        expect(TagName.exists?(source_tag.tag_name_id)).to be(false)
+      end
+    end
+  end
+end

backend/spec/models/tag_spec.rb

@@ -0,0 +1,214 @@
+require 'rails_helper'
+
+RSpec.describe Tag, type: :model do
+  describe '.merge_tags!' do
+    let!(:target_tag) { create(:tag, category: :general) }
+    let!(:source_tag) { create(:tag, category: :general) }
+    let!(:source_tag_name) { source_tag.tag_name }
+
+    let!(:post_record) do
+      Post.create!(url: 'https://example.com/posts/1', title: 'test post')
+    end
+
+    context 'when merging a simple source tag' do
+      let!(:source_post_tag) { PostTag.create!(post: post_record, tag: source_tag) }
+
+      it 'discards the source post_tag, creates an active target post_tag, discards the source tag, and aliases the source tag_name' do
+        described_class.merge_tags!(target_tag, [source_tag])
+
+        source_pt = PostTag.with_discarded.find(source_post_tag.id)
+        active_target = PostTag.kept.find_by(post_id: post_record.id, tag_id: target_tag.id)
+
+        expect(source_pt.discarded_at).to be_present
+        expect(source_pt.tag_id).to eq(source_tag.id)
+        expect(active_target).to be_present
+
+        expect(Tag.with_discarded.find(source_tag.id)).to be_discarded
+        expect(TagName.with_discarded.find(source_tag_name.id)).not_to be_discarded
+        expect(source_tag_name.reload.canonical_id).to eq(target_tag.tag_name_id)
+        expect(target_tag.reload.post_count).to eq(1)
+      end
+    end
+
+    context 'when the target already has the same post_tag' do
+      let!(:target_post_tag) { PostTag.create!(post: post_record, tag: target_tag) }
+      let!(:source_post_tag) { PostTag.create!(post: post_record, tag: source_tag) }
+
+      it 'discards the source post_tag, keeps one active target post_tag, discards the source tag, and aliases the source tag_name' do
+        described_class.merge_tags!(target_tag, [source_tag])
+
+        source_pt = PostTag.with_discarded.find(source_post_tag.id)
+        active = PostTag.kept.where(post_id: post_record.id, tag_id: target_tag.id)
+
+        expect(source_pt.discarded_at).to be_present
+        expect(source_pt.tag_id).to eq(source_tag.id)
+        expect(active.count).to eq(1)
+        expect(active.first.id).to eq(target_post_tag.id)
+
+        expect(Tag.with_discarded.find(source_tag.id)).to be_discarded
+        expect(TagName.with_discarded.find(source_tag_name.id)).not_to be_discarded
+        expect(source_tag_name.reload.canonical_id).to eq(target_tag.tag_name_id)
+        expect(target_tag.reload.post_count).to eq(1)
+      end
+    end
+
+    context 'when source_tags includes the target itself' do
+      let!(:source_post_tag) { PostTag.create!(post: post_record, tag: source_tag) }
+
+      it 'ignores the target in source_tags while still merging the source tag' do
+        described_class.merge_tags!(target_tag, [source_tag, target_tag])
+
+        source_pt = PostTag.with_discarded.find(source_post_tag.id)
+        active_target = PostTag.kept.find_by(post_id: post_record.id, tag_id: target_tag.id)
+
+        expect(Tag.find(target_tag.id)).to be_present
+        expect(Tag.with_discarded.find(source_tag.id)).to be_discarded
+        expect(source_pt.discarded_at).to be_present
+        expect(source_pt.tag_id).to eq(source_tag.id)
+        expect(active_target).to be_present
+        expect(source_tag_name.reload.canonical_id).to eq(target_tag.tag_name_id)
+        expect(target_tag.reload.post_count).to eq(1)
+      end
+    end
+
+    context 'when the source tag_name is invalid under sanitisation rules' do
+      let!(:source_post_tag) { PostTag.create!(post: post_record, tag: source_tag) }
+      let!(:sanitisation_rule) do
+        TagNameSanitisationRule.create!(
+          priority: 99_999,
+          source_pattern: 'INVALIDTOKEN',
+          replacement: ''
+        )
+      end
+
+      before do
+        source_tag_name.update_columns(
+          name: "#{ source_tag_name.name }INVALIDTOKEN",
+          updated_at: Time.current
+        )
+      end
+
+      it 'still merges, but discards the source tag_name instead of aliasing it' do
+        described_class.merge_tags!(target_tag, [source_tag])
+
+        source_pt = PostTag.with_discarded.find(source_post_tag.id)
+        active_target = PostTag.kept.find_by(post_id: post_record.id, tag_id: target_tag.id)
+        discarded_source_tag_name = TagName.with_discarded.find(source_tag_name.id)
+
+        expect(source_pt.discarded_at).to be_present
+        expect(source_pt.tag_id).to eq(source_tag.id)
+        expect(active_target).to be_present
+
+        expect(Tag.with_discarded.find(source_tag.id)).to be_discarded
+        expect(target_tag.reload.post_count).to eq(1)
+      end
+    end
+
+    context 'when the source tag_name has a wiki_page' do
+      let!(:source_post_tag) { PostTag.create!(post: post_record, tag: source_tag) }
+      let!(:wiki_page) do
+        WikiPage.create!(
+          tag_name: source_tag_name,
+          created_user: create_admin_user!,
+          updated_user: create_admin_user!
+        )
+      end
+
+      it 'rolls back the transaction' do
+        expect {
+          described_class.merge_tags!(target_tag, [source_tag])
+        }.to raise_error(ActiveRecord::RecordInvalid)
+
+        expect(Tag.with_discarded.find(source_tag.id)).not_to be_discarded
+        expect(TagName.with_discarded.find(source_tag_name.id)).not_to be_discarded
+        expect(PostTag.kept.find(source_post_tag.id).tag_id).to eq(source_tag.id)
+        expect(PostTag.kept.find_by(post_id: post_record.id, tag_id: target_tag.id)).to be_nil
+        expect(source_tag_name.reload.canonical_id).to be_nil
+        expect(target_tag.reload.post_count).to eq(0)
+      end
+    end
+
+    context 'when merging a nico source tag' do
+      let!(:target_tag) { create(:tag, category: :nico, name: 'nico:foo') }
+      let!(:source_tag) { create(:tag, category: :nico, name: 'nico:bar') }
+      let!(:source_tag_name_id) { source_tag.tag_name_id }
+
+      it 'discards the source tag_name instead of aliasing it' do
+        described_class.merge_tags!(target_tag, [source_tag])
+
+        discarded_source_tag = Tag.with_discarded.find(source_tag.id)
+        discarded_source_tag_name = TagName.with_discarded.find(source_tag_name_id)
+
+        expect(discarded_source_tag).to be_discarded
+        expect(discarded_source_tag_name).to be_discarded
+        expect(discarded_source_tag_name.canonical_id).to be_nil
+        expect(target_tag.reload.post_count).to eq(0)
+      end
+    end
+
+    def snapshot_tags(post)
+      post.snapshot_tag_names.join(' ')
+    end
+
+    def create_post_version_for!(post, version_no: 1, event_type: 'create', created_by_user: nil)
+      PostVersion.create!(
+        post: post,
+        version_no: version_no,
+        event_type: event_type,
+        title: post.title,
+        url: post.url,
+        thumbnail_base: post.thumbnail_base,
+        tags: snapshot_tags(post),
+        parent: post.parent,
+        original_created_from: post.original_created_from,
+        original_created_before: post.original_created_before,
+        created_at: Time.current,
+        created_by_user: created_by_user
+      )
+    end
+
+    context 'when post versions are enabled' do
+      let!(:source_post_tag) { PostTag.create!(post: post_record, tag: source_tag) }
+      let!(:unaffected_post) do
+        Post.create!(url: 'https://example.com/posts/2', title: 'unaffected post')
+      end
+
+      before do
+        create_post_version_for!(post_record)
+        create_post_version_for!(unaffected_post)
+      end
+
+      it 'creates an update post_version only for affected posts' do
+        expect {
+          described_class.merge_tags!(target_tag, [source_tag])
+        }.to change(PostVersion, :count).by(1)
+
+        affected_versions = post_record.reload.post_versions.order(:version_no)
+        expect(affected_versions.pluck(:version_no)).to eq([1, 2])
+
+        latest = affected_versions.last
+        expect(latest.event_type).to eq('update')
+        expect(latest.created_by_user).to be_nil
+        expect(latest.tags).to eq(snapshot_tags(post_record.reload))
+
+        expect(unaffected_post.reload.post_versions.count).to eq(1)
+      end
+    end
+
+    context 'when the source tag has no active post_tags' do
+      let!(:another_post) do
+        Post.create!(url: 'https://example.com/posts/3', title: 'another post')
+      end
+
+      before do
+        create_post_version_for!(another_post)
+      end
+
+      it 'does not create any post_version' do
+        expect {
+          described_class.merge_tags!(target_tag, [source_tag])
+        }.not_to change(PostVersion, :count)
+      end
+    end
+  end
+end

backend/spec/requests/deerjikists_spec.rb

@@ -0,0 +1,181 @@
+require 'rails_helper'
+
+RSpec.describe 'Deerjikists API', type: :request do
+  let(:platform) { 'nico' }
+  let(:code) { 'deerjika-bot' }
+
+  let!(:tag1) { create(:tag, category: :deerjikist) }
+  let!(:tag2) { create(:tag, category: :deerjikist) }
+
+  let(:member) { create(:user, :member) }
+  let(:guest) { create(:user, role: :guest) }
+
+  describe 'GET /deerjikists/:platform/:code' do
+    subject(:do_request) do
+      get "/deerjikists/#{ platform }/#{ code }"
+    end
+
+    context 'when deerjikist exists' do
+      before do
+        Deerjikist.create!(platform:, code:, tag: tag1)
+      end
+
+      it 'returns 200 and deerjikist json' do
+        do_request
+        expect(response).to have_http_status(:ok)
+
+        expect(json).to be_a(Hash)
+        expect(json['platform']).to eq(platform)
+        expect(json['code']).to eq(code)
+
+        expect(json['tag']).to be_a(Hash)
+        expect(json['tag']['id']).to eq(tag1.id)
+        expect(json['tag']['name']).to eq(tag1.name)
+      end
+    end
+
+    context 'when deerjikist does not exist' do
+      it 'returns 404' do
+        do_request
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+
+    context 'when platform or code become blank after strip' do
+      it 'returns 400' do
+        get '/deerjikists/%20/%20'
+        expect(response).to have_http_status(:bad_request)
+      end
+    end
+  end
+
+  describe 'PUT /deerjikists/:platform/:code' do
+    subject(:do_request) do
+      put "/deerjikists/#{ platform }/#{ code }", params: payload
+    end
+
+    let(:payload) { { tag_id: tag1.id } }
+
+    context 'when not legged in' do
+      it 'returns 401' do
+        sign_out
+        do_request
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when logged in but not member' do
+      it 'returns 403' do
+        sign_in_as guest
+        do_request
+        expect(response).to have_http_status(:forbidden)
+      end
+    end
+
+    context 'when member' do
+      before do
+        sign_in_as member
+      end
+
+      context 'when params invalid' do
+        it 'returns 400 when tag_id is missing or invalid' do
+          put "/deerjikists/#{ platform }/#{ code }", params: { tag_id: 0 }
+          expect(response).to have_http_status(:bad_request)
+        end
+
+        it 'returns 400 when platform or code blank after strip' do
+          put '/deerjikists/%20/%20', params: { tag_id: tag1.id }
+          expect(response).to have_http_status(:bad_request)
+        end
+      end
+
+      context 'when creating new deerjikist' do
+        it 'creates and returns 200 with json' do
+          expect { do_request }.to change { Deerjikist.count }.by(1)
+          expect(response).to have_http_status(:ok)
+
+          d = Deerjikist.find_by(platform:, code:)
+          expect(d).to be_present
+          expect(d.tag_id).to eq(tag1.id)
+
+          expect(json['platform']).to eq(platform)
+          expect(json['code']).to eq(code)
+        end
+      end
+
+      context 'when updating existing deerjikist' do
+        before do
+          Deerjikist.create!(platform:, code:, tag: tag1)
+        end
+
+        let(:payload) { { tag_id: tag2.id } }
+
+        it 'updates tag_id and returns 200' do
+          expect { do_request }.not_to change { Deerjikist.count }
+          expect(response).to have_http_status(:ok)
+
+          d = Deerjikist.find_by(platform:, code:)
+          expect(d.tag_id).to eq(tag2.id)
+
+          expect(json['platform']).to eq(platform)
+          expect(json['code']).to eq(code)
+        end
+      end
+    end
+  end
+
+  describe 'DELETE /deerjikists/:platform/:code' do
+    subject(:do_request) do
+      delete "/deerjikists/#{ platform }/#{ code }"
+    end
+
+    context 'when not logged in' do
+      it 'returns 401' do
+        sign_out
+        do_request
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when logged in but not member' do
+      it 'returns 403' do
+        sign_in_as guest
+        do_request
+        expect(response).to have_http_status(:forbidden)
+      end
+    end
+
+    context 'when member' do
+      before do
+        sign_in_as member
+      end
+
+      it 'returns 400 when platform/code blank after strip' do
+        delete '/deerjikists/%20/%20'
+        expect(response).to have_http_status(:bad_request)
+      end
+
+      context 'when deerjikist exists' do
+        before do
+          Deerjikist.create!(platform: platform, code: code, tag: tag1)
+        end
+
+        it 'destroys and returns 204' do
+          expect {
+            do_request
+          }.to change { Deerjikist.exists?(platform: platform, code: code) }
+            .from(true).to(false)
+
+          expect(response).to have_http_status(:no_content)
+        end
+      end
+
+      context 'when deerjikist does not exist' do
+        it 'returns 404' do
+          do_request
+          expect(response).to have_http_status(:not_found)
+        end
+      end
+    end
+  end
+end

backend/spec/requests/materials_spec.rb

@@ -0,0 +1,378 @@
+require 'rails_helper'
+
+RSpec.describe 'Materials API', type: :request do
+  let!(:member_user) { create(:user, :member) }
+  let!(:guest_user)  { create(:user) }
+
+  def dummy_upload(filename: 'dummy.png', type: 'image/png', body: 'dummy')
+    Rack::Test::UploadedFile.new(StringIO.new(body), type, original_filename: filename)
+  end
+
+  def response_materials
+    json.fetch('materials')
+  end
+
+  def build_material(tag:, user:, parent: nil, file: dummy_upload, url: nil)
+    Material.new(tag:, parent:, url:, created_by_user: user, updated_by_user: user).tap do |material|
+      material.file.attach(file) if file
+      material.save!
+    end
+  end
+
+  describe 'GET /materials' do
+    let!(:tag_a) { Tag.create!(tag_name: TagName.create!(name: 'material_index_a'), category: :material) }
+    let!(:tag_b) { Tag.create!(tag_name: TagName.create!(name: 'material_index_b'), category: :material) }
+
+    let!(:material_a) do
+      build_material(tag: tag_a, user: member_user, file: dummy_upload(filename: 'a.png'))
+    end
+
+    let!(:material_b) do
+      build_material(tag: tag_b, user: member_user, parent: material_a, file: dummy_upload(filename: 'b.png'))
+    end
+
+    before do
+      old_time = Time.zone.local(2026, 3, 29, 1, 0, 0)
+      new_time = Time.zone.local(2026, 3, 29, 2, 0, 0)
+
+      material_a.update_columns(created_at: old_time, updated_at: old_time)
+      material_b.update_columns(created_at: new_time, updated_at: new_time)
+    end
+
+    it 'returns materials with count and metadata' do
+      get '/materials'
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to include('materials', 'count')
+      expect(response_materials).to be_an(Array)
+      expect(json['count']).to eq(2)
+
+      row = response_materials.find { |m| m['id'] == material_b.id }
+      expect(row).to be_present
+      expect(row['tag']).to include(
+        'id' => tag_b.id,
+        'name' => 'material_index_b',
+        'category' => 'material'
+      )
+      expect(row['created_by_user']).to include(
+        'id' => member_user.id,
+        'name' => member_user.name
+      )
+      expect(row['content_type']).to eq('image/png')
+    end
+
+    it 'filters materials by tag_id' do
+      get '/materials', params: { tag_id: material_a.tag_id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(1)
+      expect(response_materials.map { |m| m['id'] }).to eq([material_a.id])
+    end
+
+    it 'filters materials by parent_id' do
+      get '/materials', params: { parent_id: material_a.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(1)
+      expect(response_materials.map { |m| m['id'] }).to eq([material_b.id])
+    end
+
+    it 'paginates and keeps total count' do
+      get '/materials', params: { page: 2, limit: 1 }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(2)
+      expect(response_materials.size).to eq(1)
+      expect(response_materials.first['id']).to eq(material_a.id)
+    end
+
+    it 'normalises invalid page and limit' do
+      get '/materials', params: { page: 0, limit: 0 }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(2)
+      expect(response_materials.size).to eq(1)
+      expect(response_materials.first['id']).to eq(material_b.id)
+    end
+  end
+
+  describe 'GET /materials/:id' do
+    let!(:tag) { Tag.create!(tag_name: TagName.create!(name: 'material_show'), category: :material) }
+    let!(:material) do
+      build_material(tag:, user: member_user, file: dummy_upload(filename: 'show.png'))
+    end
+
+    it 'returns a material with file, tag, and content_type' do
+      get "/materials/#{ material.id }"
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to include(
+        'id' => material.id,
+        'content_type' => 'image/png'
+      )
+      expect(json['file']).to be_present
+      expect(json['tag']).to include(
+        'id' => tag.id,
+        'name' => 'material_show',
+        'category' => 'material'
+      )
+    end
+
+    it 'returns 404 when material does not exist' do
+      get '/materials/999999999'
+      expect(response).to have_http_status(:not_found)
+    end
+  end
+
+  describe 'POST /materials' do
+    context 'when not logged in' do
+      before { sign_out }
+
+      it 'returns 401' do
+        post '/materials', params: {
+          tag: 'material_create_unauthorized',
+          file: dummy_upload
+        }
+
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when logged in' do
+      before { sign_in_as(guest_user) }
+
+      it 'returns 400 when tag is blank' do
+        post '/materials', params: { tag: '   ', file: dummy_upload }
+
+        expect(response).to have_http_status(:bad_request)
+      end
+
+      it 'returns 400 when both file and url are blank' do
+        post '/materials', params: { tag: 'material_create_blank' }
+
+        expect(response).to have_http_status(:bad_request)
+      end
+
+      it 'creates a material with an attached file' do
+        expect do
+          post '/materials', params: {
+            tag: 'material_create_new',
+            file: dummy_upload(filename: 'created.png')
+          }
+        end.to change(Material, :count).by(1)
+          .and change(Tag, :count).by(1)
+          .and change(TagName, :count).by(1)
+
+        expect(response).to have_http_status(:created)
+
+        material = Material.order(:id).last
+        expect(material.tag.name).to eq('material_create_new')
+        expect(material.tag.category).to eq('material')
+        expect(material.created_by_user).to eq(guest_user)
+        expect(material.updated_by_user).to eq(guest_user)
+        expect(material.file.attached?).to be(true)
+
+        expect(json['id']).to eq(material.id)
+        expect(json.dig('tag', 'name')).to eq('material_create_new')
+        expect(json['content_type']).to eq('image/png')
+      end
+
+      it 'returns 422 when the existing tag is not material/character' do
+        general_tag_name = TagName.create!(name: 'material_create_general_tag')
+        Tag.create!(tag_name: general_tag_name, category: :general)
+
+        post '/materials', params: {
+          tag: 'material_create_general_tag',
+          file: dummy_upload
+        }
+
+        expect(response).to have_http_status(:unprocessable_entity)
+      end
+
+      it 'persists url-only material' do
+        expect do
+          post '/materials', params: {
+            tag: 'material_create_url_only',
+            url: 'https://example.com/material-source'
+          }
+        end.to change(Material, :count).by(1)
+
+        expect(response).to have_http_status(:created)
+
+        material = Material.order(:id).last
+        expect(material.tag.name).to eq('material_create_url_only')
+        expect(material.url).to eq('https://example.com/material-source')
+        expect(material.file.attached?).to be(false)
+      end
+
+      it 'returns the original url for url-only material' do
+        post '/materials', params: {
+          tag: 'material_create_url_only_response',
+          url: 'https://example.com/material-source'
+        }
+
+        expect(response).to have_http_status(:created)
+        expect(json['url']).to eq('https://example.com/material-source')
+      end
+    end
+  end
+
+  describe 'PUT /materials/:id' do
+    let!(:tag) { Tag.create!(tag_name: TagName.create!(name: 'material_update_old'), category: :material) }
+    let!(:material) do
+      build_material(tag:, user: member_user, file: dummy_upload(filename: 'old.png'))
+    end
+
+    context 'when not logged in' do
+      before { sign_out }
+
+      it 'returns 401' do
+        put "/materials/#{ material.id }", params: {
+          tag: 'material_update_new',
+          file: dummy_upload(filename: 'new.png')
+        }
+
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when logged in but not member' do
+      before { sign_in_as(guest_user) }
+
+      it 'returns 403' do
+        put "/materials/#{ material.id }", params: {
+          tag: 'material_update_new',
+          file: dummy_upload(filename: 'new.png')
+        }
+
+        expect(response).to have_http_status(:forbidden)
+      end
+    end
+
+    context 'when member' do
+      before { sign_in_as(member_user) }
+
+      it 'returns 404 when material does not exist' do
+        put '/materials/999999999', params: {
+          tag: 'material_update_missing',
+          file: dummy_upload
+        }
+
+        expect(response).to have_http_status(:not_found)
+      end
+
+      it 'returns 400 when tag is blank' do
+        put "/materials/#{ material.id }", params: {
+          tag: '   ',
+          file: dummy_upload
+        }
+
+        expect(response).to have_http_status(:bad_request)
+      end
+
+      it 'returns 400 when both file and url are blank' do
+        put "/materials/#{ material.id }", params: {
+          tag: 'material_update_no_payload'
+        }
+
+        expect(response).to have_http_status(:bad_request)
+      end
+
+      it 'updates tag, url, file, and updated_by_user' do
+        old_blob_id = material.file.blob.id
+
+        put "/materials/#{ material.id }", params: {
+          tag: 'material_update_new',
+          url: 'https://example.com/updated-source',
+          file: dummy_upload(filename: 'updated.jpg', type: 'image/jpeg')
+        }
+
+        expect(response).to have_http_status(:ok)
+
+        material.reload
+        expect(material.tag.name).to eq('material_update_new')
+        expect(material.tag.category).to eq('material')
+        expect(material.url).to eq('https://example.com/updated-source')
+        expect(material.updated_by_user).to eq(member_user)
+        expect(material.file.attached?).to be(true)
+        expect(material.file.blob.id).not_to eq(old_blob_id)
+        expect(material.file.blob.filename.to_s).to eq('updated.jpg')
+        expect(material.file.blob.content_type).to eq('image/jpeg')
+
+        expect(json['id']).to eq(material.id)
+        expect(json['file']).to be_present
+        expect(json['content_type']).to eq('image/jpeg')
+        expect(json.dig('tag', 'name')).to eq('material_update_new')
+      end
+
+      it 'purges the existing file when file is omitted and url is provided' do
+        old_blob_id = material.file.blob.id
+
+        put "/materials/#{ material.id }", params: {
+          tag: 'material_update_remove_file',
+          url: 'https://example.com/updated-source'
+        }
+
+        expect(response).to have_http_status(:ok)
+
+        material.reload
+        expect(material.tag.name).to eq('material_update_remove_file')
+        expect(material.url).to eq('https://example.com/updated-source')
+        expect(material.updated_by_user).to eq(member_user)
+        expect(material.file.attached?).to be(false)
+
+        expect(
+          ActiveStorage::Blob.where(id: old_blob_id).exists?
+        ).to be(false)
+
+        expect(json['id']).to eq(material.id)
+        expect(json['file']).to be_nil
+        expect(json['content_type']).to be_nil
+        expect(json.dig('tag', 'name')).to eq('material_update_remove_file')
+        expect(json['url']).to eq('https://example.com/updated-source')
+      end
+    end
+  end
+
+  describe 'DELETE /materials/:id' do
+    let!(:tag) { Tag.create!(tag_name: TagName.create!(name: 'material_destroy'), category: :material) }
+    let!(:material) do
+      build_material(tag:, user: member_user, file: dummy_upload(filename: 'destroy.png'))
+    end
+
+    context 'when not logged in' do
+      before { sign_out }
+
+      it 'returns 401' do
+        delete "/materials/#{ material.id }"
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when logged in but not member' do
+      before { sign_in_as(guest_user) }
+
+      it 'returns 403' do
+        delete "/materials/#{ material.id }"
+        expect(response).to have_http_status(:forbidden)
+      end
+    end
+
+    context 'when member' do
+      before { sign_in_as(member_user) }
+
+      it 'returns 404 when material does not exist' do
+        delete '/materials/999999999'
+        expect(response).to have_http_status(:not_found)
+      end
+
+      it 'discards the material and returns 204' do
+        delete "/materials/#{ material.id }"
+
+        expect(response).to have_http_status(:no_content)
+        expect(Material.find_by(id: material.id)).to be_nil
+        expect(Material.with_discarded.find(material.id)).to be_discarded
+      end
+    end
+  end
+end

backend/spec/requests/posts_spec.rb

@@ -1,7 +1,8 @@
+include ActiveSupport::Testing::TimeHelpers
+
 require 'rails_helper'
 require 'set'
 
-
 RSpec.describe 'Posts API', type: :request do
   # create / update で thumbnail.attach は走るが、
   # resized_thumbnail! が MiniMagick 依存でコケやすいので request spec ではスタブしとくのが無難。
@@ -15,7 +16,7 @@ RSpec.describe 'Posts API', type: :request do
   end
 
   let!(:tag_name) { TagName.create!(name: 'spec_tag') }
-  let!(:tag)      { Tag.create!(tag_name: tag_name, category: 'general') }
+  let!(:tag)      { Tag.create!(tag_name: tag_name, category: :general) }
 
   let!(:post_record) do
     Post.create!(title: 'spec post', url: 'https://example.com/spec').tap do |p|
@@ -27,9 +28,9 @@ RSpec.describe 'Posts API', type: :request do
     let!(:user) { create_member_user! }
 
     let!(:tag_name) { TagName.create!(name: "spec_tag") }
-    let!(:tag) { Tag.create!(tag_name:, category: "general") }
+    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!(:tag2) { Tag.create!(tag_name: tag_name2, category: :deerjikist) }
     let!(:alias_tag_name) { TagName.create!(name: 'manko', canonical: tag_name) }
 
     let!(:hit_post) do
@@ -114,6 +115,321 @@ RSpec.describe 'Posts API', type: :request do
         expect(json.fetch('count')).to eq(0)
       end
     end
+
+    context 'when tags contain not:' do
+      let!(:foo_tag_name) { TagName.create!(name: 'not_spec_foo') }
+      let!(:foo_tag) { Tag.create!(tag_name: foo_tag_name, category: :general) }
+
+      let!(:bar_tag_name) { TagName.create!(name: 'not_spec_bar') }
+      let!(:bar_tag) { Tag.create!(tag_name: bar_tag_name, category: :general) }
+
+      let!(:baz_tag_name) { TagName.create!(name: 'not_spec_baz') }
+      let!(:baz_tag) { Tag.create!(tag_name: baz_tag_name, category: :general) }
+
+      let!(:foo_alias_tag_name) do
+        TagName.create!(name: 'not_spec_foo_alias', canonical: foo_tag_name)
+      end
+
+      let!(:foo_only_post) do
+        Post.create!(uploaded_user: user, title: 'foo only',
+                     url: 'https://example.com/not-spec-foo').tap do |p|
+          PostTag.create!(post: p, tag: foo_tag)
+        end
+      end
+
+      let!(:bar_only_post) do
+        Post.create!(uploaded_user: user, title: 'bar only',
+                     url: 'https://example.com/not-spec-bar').tap do |p|
+          PostTag.create!(post: p, tag: bar_tag)
+        end
+      end
+
+      let!(:baz_only_post) do
+        Post.create!(uploaded_user: user, title: 'baz only',
+                     url: 'https://example.com/not-spec-baz').tap do |p|
+          PostTag.create!(post: p, tag: baz_tag)
+        end
+      end
+
+      let!(:foo_bar_post) do
+        Post.create!(uploaded_user: user, title: 'foo bar',
+                     url: 'https://example.com/not-spec-foo-bar').tap do |p|
+          PostTag.create!(post: p, tag: foo_tag)
+          PostTag.create!(post: p, tag: bar_tag)
+        end
+      end
+
+      let!(:foo_baz_post) do
+        Post.create!(uploaded_user: user, title: 'foo baz',
+                     url: 'https://example.com/not-spec-foo-baz').tap do |p|
+          PostTag.create!(post: p, tag: foo_tag)
+          PostTag.create!(post: p, tag: baz_tag)
+        end
+      end
+
+      let(:controlled_ids) do
+        [foo_only_post.id, bar_only_post.id, baz_only_post.id,
+         foo_bar_post.id, foo_baz_post.id]
+      end
+
+      it 'supports not search' do
+        get '/posts', params: { tags: 'not:not_spec_foo' }
+
+        expect(response).to have_http_status(:ok)
+
+        expect(json.fetch('posts').map { |p| p['id'] } & controlled_ids).to match_array(
+          [bar_only_post.id, baz_only_post.id]
+        )
+      end
+
+      it 'supports alias in not search' do
+        get '/posts', params: { tags: 'not:not_spec_foo_alias' }
+
+        expect(response).to have_http_status(:ok)
+
+        expect(json.fetch('posts').map { |p| p['id'] } & controlled_ids).to match_array(
+          [bar_only_post.id, baz_only_post.id]
+        )
+      end
+
+      it 'treats multiple not terms as AND when match is omitted' do
+        get '/posts', params: { tags: 'not:not_spec_foo not:not_spec_bar' }
+
+        expect(response).to have_http_status(:ok)
+
+        expect(json.fetch('posts').map { |p| p['id'] } & controlled_ids).to match_array(
+          [baz_only_post.id]
+        )
+      end
+
+      it 'treats multiple not terms as OR when match=any' do
+        get '/posts', params: { tags: 'not:not_spec_foo not:not_spec_bar', match: 'any' }
+
+        expect(response).to have_http_status(:ok)
+
+        expect(json.fetch('posts').map { |p| p['id'] } & controlled_ids).to match_array(
+          [foo_only_post.id, bar_only_post.id, baz_only_post.id, foo_baz_post.id]
+        )
+      end
+
+      it 'supports mixed positive and negative search with AND' do
+        get '/posts', params: { tags: 'not_spec_foo not:not_spec_bar' }
+
+        expect(response).to have_http_status(:ok)
+
+        expect(json.fetch('posts').map { |p| p['id'] } & controlled_ids).to match_array(
+          [foo_only_post.id, foo_baz_post.id]
+        )
+      end
+
+      it 'supports mixed positive and negative search with OR when match=any' do
+        get '/posts', params: { tags: 'not_spec_foo not:not_spec_bar', match: 'any' }
+
+        expect(response).to have_http_status(:ok)
+
+        expect(json.fetch('posts').map { |p| p['id'] } & controlled_ids).to match_array(
+          [foo_only_post.id, baz_only_post.id, foo_bar_post.id, foo_baz_post.id]
+        )
+      end
+    end
+
+    context 'when url is provided' do
+      let!(:url_hit_post) do
+        Post.create!(uploaded_user: user, title: 'url hit',
+                     url: 'https://example.com/needle-url-xyz').tap do |p|
+          PostTag.create!(post: p, tag:)
+        end
+      end
+
+      let!(:url_miss_post) do
+        Post.create!(uploaded_user: user, title: 'url miss',
+                     url: 'https://example.com/other-url').tap do |p|
+          PostTag.create!(post: p, tag:)
+        end
+      end
+
+      it 'filters posts by url substring' do
+        get '/posts', params: { url: 'needle-url-xyz' }
+
+        expect(response).to have_http_status(:ok)
+        ids = json.fetch('posts').map { |p| p['id'] }
+
+        expect(ids).to include(url_hit_post.id)
+        expect(ids).not_to include(url_miss_post.id)
+        expect(json.fetch('count')).to eq(1)
+      end
+    end
+
+    context 'when title is provided' do
+      let!(:title_hit_post) do
+        Post.create!(uploaded_user: user, title: 'needle-title-xyz',
+                     url: 'https://example.com/title-hit').tap do |p|
+          PostTag.create!(post: p, tag:)
+        end
+      end
+
+      let!(:title_miss_post) do
+        Post.create!(uploaded_user: user, title: 'other title',
+                     url: 'https://example.com/title-miss').tap do |p|
+          PostTag.create!(post: p, tag:)
+        end
+      end
+
+      it 'filters posts by title substring' do
+        get '/posts', params: { title: 'needle-title-xyz' }
+
+        expect(response).to have_http_status(:ok)
+        ids = json.fetch('posts').map { |p| p['id'] }
+
+        expect(ids).to include(title_hit_post.id)
+        expect(ids).not_to include(title_miss_post.id)
+        expect(json.fetch('count')).to eq(1)
+      end
+    end
+
+    context 'when created_from/created_to are provided' do
+      let(:t_created_hit) { Time.zone.local(2010, 1, 5, 12, 0, 0) }
+      let(:t_created_miss) { Time.zone.local(2012, 1, 5, 12, 0, 0) }
+
+      let!(:created_hit_post) do
+        travel_to(t_created_hit) do
+          Post.create!(uploaded_user: user, title: 'created hit',
+                       url: 'https://example.com/created-hit').tap do |p|
+            PostTag.create!(post: p, tag:)
+          end
+        end
+      end
+
+      let!(:created_miss_post) do
+        travel_to(t_created_miss) do
+          Post.create!(uploaded_user: user, title: 'created miss',
+                       url: 'https://example.com/created-miss').tap do |p|
+            PostTag.create!(post: p, tag:)
+          end
+        end
+      end
+
+      it 'filters posts by created_at range' do
+        get '/posts', params: {
+          created_from: Time.zone.local(2010, 1, 1, 0, 0, 0).iso8601,
+          created_to: Time.zone.local(2010, 12, 31, 23, 59, 59).iso8601
+        }
+
+        expect(response).to have_http_status(:ok)
+        ids = json.fetch('posts').map { |p| p['id'] }
+
+        expect(ids).to include(created_hit_post.id)
+        expect(ids).not_to include(created_miss_post.id)
+        expect(json.fetch('count')).to eq(1)
+      end
+    end
+
+    context 'when updated_from/updated_to are provided' do
+      let(:t0) { Time.zone.local(2011, 2, 1, 12, 0, 0) }
+      let(:t1) { Time.zone.local(2011, 2, 10, 12, 0, 0) }
+
+      let!(:updated_hit_post) do
+        p = nil
+        travel_to(t0) do
+          p = Post.create!(uploaded_user: user, title: 'updated hit',
+                           url: 'https://example.com/updated-hit').tap do |pp|
+            PostTag.create!(post: pp, tag:)
+          end
+        end
+        travel_to(t1) do
+          p.update!(title: 'updated hit v2')
+        end
+        p
+      end
+
+      let!(:updated_miss_post) do
+        travel_to(Time.zone.local(2013, 1, 1, 12, 0, 0)) do
+          Post.create!(uploaded_user: user, title: 'updated miss',
+                       url: 'https://example.com/updated-miss').tap do |p|
+            PostTag.create!(post: p, tag:)
+          end
+        end
+      end
+
+      it 'filters posts by updated_at range' do
+        get '/posts', params: {
+          updated_from: Time.zone.local(2011, 2, 5, 0, 0, 0).iso8601,
+          updated_to: Time.zone.local(2011, 2, 20, 23, 59, 59).iso8601
+        }
+
+        expect(response).to have_http_status(:ok)
+        ids = json.fetch('posts').map { |p| p['id'] }
+
+        expect(ids).to include(updated_hit_post.id)
+        expect(ids).not_to include(updated_miss_post.id)
+        expect(json.fetch('count')).to eq(1)
+      end
+    end
+
+    context 'when original_created_from/original_created_to are provided' do
+      # 注意: controller の現状ロジックに合わせてる
+      # original_created_from は `original_created_before > ?`
+      # original_created_to   は `original_created_from <= ?`
+
+      let!(:oc_hit_post) do
+        Post.create!(uploaded_user: user, title: 'oc hit',
+                     url: 'https://example.com/oc-hit',
+                     original_created_from: Time.zone.local(2015, 1, 1, 0, 0, 0),
+                     original_created_before: Time.zone.local(2015, 1, 10, 0, 0, 0)).tap do |p|
+          PostTag.create!(post: p, tag:)
+        end
+      end
+
+      # original_created_from の条件は「original_created_before > param」なので、
+      # before が param 以下になるようにする（ただし before >= from は守る）
+      let!(:oc_miss_post_for_from) do
+        Post.create!(
+          uploaded_user: user,
+          title: 'oc miss for from',
+          url: 'https://example.com/oc-miss-from',
+          original_created_from: Time.zone.local(2014, 12, 1, 0, 0, 0),
+          original_created_before: Time.zone.local(2015, 1, 1, 0, 0, 0)
+        ).tap { |p| PostTag.create!(post: p, tag:) }
+      end
+
+      # original_created_to の条件は「original_created_from <= param」なので、
+      # from が param より後になるようにする（before >= from は守る）
+      let!(:oc_miss_post_for_to) do
+        Post.create!(
+          uploaded_user: user,
+          title: 'oc miss for to',
+          url: 'https://example.com/oc-miss-to',
+          original_created_from: Time.zone.local(2015, 2, 1, 0, 0, 0),
+          original_created_before: Time.zone.local(2015, 2, 10, 0, 0, 0)
+        ).tap { |p| PostTag.create!(post: p, tag:) }
+      end
+
+      it 'filters posts by original_created_from (current controller behavior)' do
+        get '/posts', params: {
+          original_created_from: Time.zone.local(2015, 1, 5, 0, 0, 0).iso8601
+        }
+
+        expect(response).to have_http_status(:ok)
+        ids = json.fetch('posts').map { |p| p['id'] }
+
+        expect(ids).to include(oc_hit_post.id)
+        expect(ids).not_to include(oc_miss_post_for_from.id)
+        expect(json.fetch('count')).to eq(2)
+      end
+
+      it 'filters posts by original_created_to (current controller behavior)' do
+        get '/posts', params: {
+          original_created_to: Time.zone.local(2015, 1, 15, 0, 0, 0).iso8601
+        }
+
+        expect(response).to have_http_status(:ok)
+        ids = json.fetch('posts').map { |p| p['id'] }
+
+        expect(ids).to include(oc_hit_post.id)
+        expect(ids).not_to include(oc_miss_post_for_to.id)
+        expect(json.fetch('count')).to eq(2)
+      end
+    end
   end
 
   describe 'GET /posts/:id' do
@@ -209,8 +525,9 @@ RSpec.describe 'Posts API', type: :request do
 
     context "when nico tag already exists in tags" do
       before do
-        Tag.find_or_create_by!(tag_name: TagName.find_or_create_by!(name: 'nico:nico_tag'),
-                               category: 'nico')
+        Tag.find_undiscard_or_create_by!(
+            tag_name: TagName.find_undiscard_or_create_by!(name: 'nico:nico_tag'),
+            category: :nico)
       end
 
       it 'return 400' do
@@ -276,7 +593,7 @@ RSpec.describe 'Posts API', type: :request do
 
       # 追加で別タグも作って、更新時に入れ替わることを見る
       tn2 = TagName.create!(name: 'spec_tag_2')
-      Tag.create!(tag_name: tn2, category: 'general')
+      Tag.create!(tag_name: tn2, category: :general)
 
       put "/posts/#{post_record.id}", params: {
         title: 'updated title',
@@ -294,8 +611,9 @@ RSpec.describe 'Posts API', type: :request do
 
     context "when nico tag already exists in tags" do
       before do
-        Tag.find_or_create_by!(tag_name: TagName.find_or_create_by!(name: 'nico:nico_tag'),
-                               category: 'nico')
+        Tag.find_undiscard_or_create_by!(
+            tag_name: TagName.find_undiscard_or_create_by!(name: 'nico:nico_tag'),
+            category: :nico)
       end
 
       it 'return 400' do
@@ -332,7 +650,7 @@ RSpec.describe 'Posts API', type: :request do
     it 'returns add/remove events (history) for a post' do
       # add
       tn2 = TagName.create!(name: 'spec_tag2')
-      tag2 = Tag.create!(tag_name: tn2, category: 'general')
+      tag2 = Tag.create!(tag_name: tn2, category: :general)
       pt = PostTag.create!(post: post_record, tag: tag2, created_user: member)
 
       # remove (discard)
@@ -349,6 +667,305 @@ RSpec.describe 'Posts API', type: :request do
       expect(types).to include('add')
       expect(types).to include('remove')
     end
+
+    it 'filters history by tag' do
+      tn2 = TagName.create!(name: 'history_tag_hit')
+      tag2 = Tag.create!(tag_name: tn2, category: :general)
+
+      tn3 = TagName.create!(name: 'history_tag_miss')
+      tag3 = Tag.create!(tag_name: tn3, category: :general)
+
+      other_post = Post.create!(
+        title: 'other post',
+        url: 'https://example.com/history-other'
+      )
+
+      # hit: add
+      PostTag.create!(post: post_record, tag: tag2, created_user: member)
+
+      # hit: add + remove
+      pt2 = PostTag.create!(post: other_post, tag: tag2, created_user: member)
+      pt2.discard_by!(member)
+
+      # miss: add + remove
+      pt3 = PostTag.create!(post: post_record, tag: tag3, created_user: member)
+      pt3.discard_by!(member)
+
+      get '/posts/changes', params: { tag: tag2.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to include('changes', 'count')
+      expect(json['count']).to eq(3)
+
+      changes = json.fetch('changes')
+
+      expect(changes.map { |e| e.dig('tag', 'id') }.uniq).to eq([tag2.id])
+      expect(changes.map { |e| e['change_type'] }).to match_array(%w[add add remove])
+      expect(changes.map { |e| e.dig('post', 'id') }).to match_array([
+        post_record.id,
+        other_post.id,
+        other_post.id
+      ])
+    end
+
+    it 'filters history by post and tag together' do
+      tn2 = TagName.create!(name: 'history_tag_combo_hit')
+      tag2 = Tag.create!(tag_name: tn2, category: :general)
+
+      tn3 = TagName.create!(name: 'history_tag_combo_miss')
+      tag3 = Tag.create!(tag_name: tn3, category: :general)
+
+      other_post = Post.create!(
+        title: 'other combo post',
+        url: 'https://example.com/history-combo-other'
+      )
+
+      # hit
+      PostTag.create!(post: post_record, tag: tag2, created_user: member)
+
+      # miss by post
+      pt2 = PostTag.create!(post: other_post, tag: tag2, created_user: member)
+      pt2.discard_by!(member)
+
+      # miss by tag
+      pt3 = PostTag.create!(post: post_record, tag: tag3, created_user: member)
+      pt3.discard_by!(member)
+
+      get '/posts/changes', params: { id: post_record.id, tag: tag2.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to include('changes', 'count')
+      expect(json['count']).to eq(1)
+
+      changes = json.fetch('changes')
+      expect(changes.size).to eq(1)
+      expect(changes[0]['change_type']).to eq('add')
+      expect(changes[0].dig('post', 'id')).to eq(post_record.id)
+      expect(changes[0].dig('tag', 'id')).to eq(tag2.id)
+    end
+
+    it 'returns empty history when tag does not match' do
+      tn2 = TagName.create!(name: 'history_tag_no_hit')
+      tag2 = Tag.create!(tag_name: tn2, category: :general)
+
+      get '/posts/changes', params: { tag: tag2.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json.fetch('changes')).to eq([])
+      expect(json.fetch('count')).to eq(0)
+    end
+  end
+
+  describe 'GET /posts/versions' do
+    let(:member) { create(:user, :member, name: 'version member') }
+
+    let(:t_v1) { Time.zone.local(2020, 1, 1, 12, 0, 0) }
+    let(:t_v2) { Time.zone.local(2020, 1, 2, 12, 0, 0) }
+    let(:t_other) { Time.zone.local(2020, 1, 3, 12, 0, 0) }
+
+    let(:oc_from) { Time.zone.local(2019, 12, 31, 0, 0, 0) }
+    let(:oc_before) { Time.zone.local(2020, 1, 1, 0, 0, 0) }
+
+    let!(:tag_name2) { TagName.create!(name: 'spec_tag_2') }
+    let!(:tag2) { Tag.create!(tag_name: tag_name2, category: :general) }
+
+    def snapshot_tags(post)
+      post.snapshot_tag_names.join(' ')
+    end
+
+    def create_post_version!(post, version_no:, event_type:, created_by_user:, created_at:)
+      PostVersion.create!(
+        post: post,
+        version_no: version_no,
+        event_type: event_type,
+        title: post.title,
+        url: post.url,
+        thumbnail_base: post.thumbnail_base,
+        tags: snapshot_tags(post),
+        parent: post.parent,
+        original_created_from: post.original_created_from,
+        original_created_before: post.original_created_before,
+        created_at: created_at,
+        created_by_user: created_by_user
+      )
+    end
+
+    let!(:v1) do
+      travel_to(t_v1) do
+        create_post_version!(
+          post_record,
+          version_no: 1,
+          event_type: 'create',
+          created_by_user: member,
+          created_at: t_v1
+        )
+      end
+    end
+
+    let!(:v2) do
+      post_record.post_tags.kept.find_by!(tag: tag).discard_by!(member)
+      PostTag.create!(post: post_record, tag: tag2, created_user: member)
+      post_record.update!(
+        title: 'updated spec post',
+        original_created_from: oc_from,
+        original_created_before: oc_before
+      )
+
+      travel_to(t_v2) do
+        create_post_version!(
+          post_record.reload,
+          version_no: 2,
+          event_type: 'update',
+          created_by_user: member,
+          created_at: t_v2
+        )
+      end
+    end
+
+    let!(:other_post_version) do
+      other_post = Post.create!(
+        title: 'other versioned post',
+        url: 'https://example.com/other-versioned'
+      )
+      PostTag.create!(post: other_post, tag: tag)
+
+      travel_to(t_other) do
+        create_post_version!(
+          other_post,
+          version_no: 1,
+          event_type: 'create',
+          created_by_user: member,
+          created_at: t_other
+        )
+      end
+    end
+
+    it 'returns versions for the specified post in reverse chronological order' do
+      get '/posts/versions', params: { post: post_record.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to include('versions', 'count')
+      expect(json.fetch('count')).to eq(2)
+
+      versions = json.fetch('versions')
+      expect(versions.map { |v| v['post_id'] }.uniq).to eq([post_record.id])
+      expect(versions.map { |v| v['version_no'] }).to eq([2, 1])
+
+      latest = versions.first
+      expect(latest).to include(
+        'post_id' => post_record.id,
+        'version_no' => 2,
+        'event_type' => 'update',
+        'created_by_user' => {
+          'id' => member.id,
+          'name' => member.name
+        }
+      )
+
+      expect(latest.fetch('title')).to eq(
+        'current' => 'updated spec post',
+        'prev' => 'spec post'
+      )
+      expect(latest.fetch('url')).to eq(
+        'current' => 'https://example.com/spec',
+        'prev' => 'https://example.com/spec'
+      )
+      expect(latest.fetch('thumbnail')).to eq(
+        'current' => nil,
+        'prev' => nil
+      )
+      expect(latest.fetch('thumbnail_base')).to eq(
+        'current' => nil,
+        'prev' => nil
+      )
+      expect(latest.fetch('tags')).to include(
+        { 'name' => 'spec_tag_2', 'type' => 'added' },
+        { 'name' => 'spec_tag', 'type' => 'removed' }
+      )
+      expect(latest.fetch('original_created_from')).to eq(
+        'current' => oc_from.iso8601,
+        'prev' => nil
+      )
+      expect(latest.fetch('original_created_before')).to eq(
+        'current' => oc_before.iso8601,
+        'prev' => nil
+      )
+      expect(latest.fetch('created_at')).to eq(t_v2.iso8601)
+
+      first = versions.second
+      expect(first).to include(
+        'post_id' => post_record.id,
+        'version_no' => 1,
+        'event_type' => 'create',
+        'created_by_user' => {
+          'id' => member.id,
+          'name' => member.name
+        }
+      )
+      expect(first.fetch('title')).to eq(
+        'current' => 'spec post',
+        'prev' => nil
+      )
+      expect(first.fetch('tags')).to include(
+        { 'name' => 'spec_tag', 'type' => 'added' }
+      )
+      expect(first.fetch('created_at')).to eq(t_v1.iso8601)
+    end
+
+    it 'filters versions by tag when the current snapshot includes the tag' do
+      get '/posts/versions', params: { post: post_record.id, tag: tag2.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json.fetch('count')).to eq(1)
+
+      versions = json.fetch('versions')
+      expect(versions.size).to eq(1)
+      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' }
+      )
+    end
+
+    it 'filters versions by tag when the tag exists in either current or previous snapshot' do
+      get '/posts/versions', params: { post: post_record.id, tag: tag.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json.fetch('count')).to eq(2)
+
+      versions = json.fetch('versions')
+      expect(versions.map { |v| v['post_id'] }).to all(eq(post_record.id))
+      expect(versions.map { |v| v['version_no'] }).to eq([2, 1])
+
+      latest = versions[0]
+      first = versions[1]
+
+      expect(latest['tags']).to include(
+        { 'name' => 'spec_tag', 'type' => 'removed' }
+      )
+      expect(first['tags']).to include(
+        { 'name' => 'spec_tag', 'type' => 'added' }
+      )
+    end
+
+    it 'returns empty when tag does not exist' do
+      get '/posts/versions', params: { tag: 999_999_999 }
+
+      expect(response).to have_http_status(:ok)
+      expect(json.fetch('versions')).to eq([])
+      expect(json.fetch('count')).to eq(0)
+    end
+
+    it 'clamps page and limit to at least 1' do
+      get '/posts/versions', params: { post: post_record.id, page: 0, limit: 0 }
+
+      expect(response).to have_http_status(:ok)
+      expect(json.fetch('count')).to eq(2)
+
+      versions = json.fetch('versions')
+      expect(versions.size).to eq(1)
+      expect(versions[0]['version_no']).to eq(2)
+    end
   end
 
   describe 'POST /posts/:id/viewed' do
@@ -390,4 +1007,127 @@ RSpec.describe 'Posts API', type: :request do
       expect(user.reload.viewed?(post_record)).to be(false)
     end
   end
+
+  describe 'post versioning' do
+    let(:member) { create(:user, :member) }
+
+    def snapshot_tags(post)
+      post.snapshot_tag_names.join(' ')
+    end
+
+    def create_post_version_for!(post)
+      PostVersion.create!(
+        post: post,
+        version_no: 1,
+        event_type: 'create',
+        title: post.title,
+        url: post.url,
+        thumbnail_base: post.thumbnail_base,
+        tags: snapshot_tags(post),
+        parent: post.parent,
+        original_created_from: post.original_created_from,
+        original_created_before: post.original_created_before,
+        created_at: post.created_at,
+        created_by_user: post.uploaded_user
+      )
+    end
+
+    it 'creates version 1 on POST /posts' do
+      sign_in_as(member)
+
+      expect do
+        post '/posts', params: {
+          title: 'versioned post',
+          url: 'https://example.com/versioned-post',
+          tags: 'spec_tag',
+          thumbnail: dummy_upload
+        }
+      end.to change(PostVersion, :count).by(1)
+
+      expect(response).to have_http_status(:created)
+
+      created_post = Post.find(json.fetch('id'))
+      version = PostVersion.find_by!(post: created_post, version_no: 1)
+
+      expect(version.event_type).to eq('create')
+      expect(version.title).to eq('versioned post')
+      expect(version.url).to eq('https://example.com/versioned-post')
+      expect(version.created_by_user_id).to eq(member.id)
+      expect(version.tags).to eq(snapshot_tags(created_post))
+    end
+
+    it 'creates next version on PUT /posts/:id when snapshot changes' do
+      sign_in_as(member)
+      create_post_version_for!(post_record)
+
+      tag_name2 = TagName.create!(name: 'spec_tag_2')
+      Tag.create!(tag_name: tag_name2, category: :general)
+
+      expect do
+        put "/posts/#{post_record.id}", params: {
+          title: 'updated title',
+          tags: 'spec_tag_2'
+        }
+      end.to change(PostVersion, :count).by(1)
+
+      expect(response).to have_http_status(:ok)
+
+      version = post_record.reload.post_versions.order(:version_no).last
+      expect(version.version_no).to eq(2)
+      expect(version.event_type).to eq('update')
+      expect(version.title).to eq('updated title')
+      expect(version.created_by_user_id).to eq(member.id)
+      expect(version.tags).to eq(snapshot_tags(post_record.reload))
+    end
+
+    it 'does not create a new version on PUT /posts/:id when snapshot is unchanged' do
+      sign_in_as(member)
+      create_post_version_for!(post_record)
+
+      expect do
+        put "/posts/#{post_record.id}", params: {
+          title: post_record.title,
+          tags: 'spec_tag'
+        }
+      end.not_to change(PostVersion, :count)
+
+      expect(response).to have_http_status(:ok)
+
+      version = post_record.reload.post_versions.order(:version_no).last
+      expect(version.version_no).to eq(1)
+      expect(version.event_type).to eq('create')
+      expect(version.tags).to eq(snapshot_tags(post_record))
+    end
+
+    it 'does not create a version when POST /posts is invalid' do
+      sign_in_as(member)
+
+      expect do
+        post '/posts', params: {
+          title: 'invalid post',
+          url: 'ぼざクリタグ広場',
+          tags: 'spec_tag',
+          thumbnail: dummy_upload
+        }
+      end.not_to change(PostVersion, :count)
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+
+    it 'does not create a version when PUT /posts/:id is invalid' do
+      sign_in_as(member)
+      create_post_version_for!(post_record)
+
+      expect do
+        put "/posts/#{post_record.id}", params: {
+          title: 'updated title',
+          tags: 'spec_tag',
+          original_created_from: Time.zone.local(2020, 1, 2, 0, 0, 0).iso8601,
+          original_created_before: Time.zone.local(2020, 1, 1, 0, 0, 0).iso8601
+        }
+      end.not_to change(PostVersion, :count)
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+  end
 end

backend/spec/requests/tag_children_spec.rb

@@ -1,4 +1,3 @@
-# spec/requests/tag_children_spec.rb
 require "rails_helper"
 
 RSpec.describe "TagChildren", type: :request do

backend/spec/requests/tags_deerjikists_spec.rb

@@ -0,0 +1,102 @@
+require 'rails_helper'
+
+RSpec.describe 'Tags deerjikists API', type: :request do
+  let(:platform1) { 'nico' }
+  let(:code1) { 'deerjika-bot' }
+  let(:platform2) { 'youtube' }
+  let(:code2) { 'deerjika-bot.bsky.social' }
+
+  let!(:tag) { create(:tag, category: :deerjikist) }
+
+  before do
+    # show_by_name / deerjikists_by_name 用に名前を固定
+    tag.tag_name.update!(name: 'deerjika')
+  end
+
+  describe 'GET /tags/:id/deerjikists' do
+    subject(:do_request) do
+      get "/tags/#{ tag_id }/deerjikists"
+    end
+
+    let(:tag_id) { tag.id }
+
+    context 'when tag exists and has no deerjikists' do
+      it 'returns 200 and empty array' do
+        do_request
+        expect(response).to have_http_status(:ok)
+        expect(json).to eq([])
+      end
+    end
+
+    context 'when tag exists and has deerjikists' do
+      before do
+        Deerjikist.create!(platform: platform1, code: code1, tag: tag)
+        Deerjikist.create!(platform: platform2, code: code2, tag: tag)
+      end
+
+      it 'returns 200 and deerjikists array' do
+        do_request
+        expect(response).to have_http_status(:ok)
+
+        expect(json).to be_a(Array)
+        expect(json.size).to eq(2)
+
+        expect(json.map { |h| [h['platform'], h['code']] }).to contain_exactly(
+          [platform1, code1],
+          [platform2, code2],
+        )
+      end
+    end
+
+    context 'when tag does not exist' do
+      let(:tag_id) { 9_999_999 }
+
+      it 'returns 404' do
+        do_request
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+  end
+
+  describe 'GET /tags/name/:name/deerjikists' do
+    subject(:do_request) do
+      get "/tags/name/#{ name }/deerjikists"
+    end
+
+    let(:name) { 'deerjika' }
+
+    context 'when name is blank after strip' do
+      let(:name) { '%20' }
+
+      it 'returns 400' do
+        do_request
+        expect(response).to have_http_status(:bad_request)
+      end
+    end
+
+    context 'when tag does not exist for name' do
+      let(:name) { 'no-such-tag' }
+
+      it 'returns 404' do
+        do_request
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+
+    context 'when tag exists and has deerjikists' do
+      before do
+        Deerjikist.create!(platform: platform1, code: code1, tag: tag)
+      end
+
+      it 'returns 200 and deerjikists array' do
+        do_request
+        expect(response).to have_http_status(:ok)
+
+        expect(json).to be_a(Array)
+        expect(json.size).to eq(1)
+        expect(json[0]['platform']).to eq(platform1)
+        expect(json[0]['code']).to eq(code1)
+      end
+    end
+  end
+end

backend/spec/requests/tags_spec.rb

@@ -11,16 +11,191 @@ RSpec.describe 'Tags API', type: :request do
   let!(:tn2) { TagName.create!(name: 'unknown') }
   let!(:tag2) { Tag.create!(tag_name: tn2, category: :general) }
 
+  def response_tags
+    json.fetch('tags')
+  end
+
+  def response_names
+    response_tags.map { |t| t.fetch('name') }
+  end
+
+  def dummy_material_upload(filename: 'dummy.png', type: 'image/png', body: 'dummy')
+    Rack::Test::UploadedFile.new(StringIO.new(body), type, original_filename: filename)
+  end
+
+  def create_material(tag, user:, filename: 'dummy.png', type: 'image/png', url: nil)
+    Material.new(tag:, url:, created_by_user: user, updated_by_user: user).tap do |material|
+      material.file.attach(dummy_material_upload(filename:, type:)) if filename
+      material.save!
+    end
+  end
+
   describe 'GET /tags' do
-    it 'returns tags with name' do
+    it 'returns tags with count and metadata' do
       get '/tags'
 
       expect(response).to have_http_status(:ok)
+      expect(json).to include('tags', 'count')
+      expect(response_tags).to be_an(Array)
+      expect(json['count']).to be_an(Integer)
+      expect(json['count']).to be >= response_tags.size
 
-      expect(json).to be_an(Array)
-      expect(json).not_to be_empty
-      expect(json[0]).to have_key('name')
-      expect(json.map { |t| t['name'] }).to include('spec_tag')
+      row = response_tags.find { |t| t['name'] == 'spec_tag' }
+      expect(row).to include(
+          'id' => tag.id,
+          'name' => 'spec_tag',
+          'category' => 'general',
+          'post_count' => 1,
+          'has_wiki' => false)
+      expect(row).to have_key('created_at')
+      expect(row).to have_key('updated_at')
+    end
+
+    it 'filters tags by post id' do
+      get '/tags', params: { post: post.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(1)
+      expect(response_names).to eq(['spec_tag'])
+    end
+
+    it 'filters tags by partial name' do
+      get '/tags', params: { name: 'spec' }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_names).to include('spec_tag')
+      expect(response_names).not_to include('unknown')
+    end
+
+    it 'filters tags by category' do
+      meme = Tag.create!(tag_name: TagName.create!(name: 'meme_only'), category: :meme)
+
+      get '/tags', params: { category: 'meme' }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_names).to eq(['meme_only'])
+      expect(response_tags.first['id']).to eq(meme.id)
+    end
+
+    it 'filters tags by post_count range' do
+      low = Tag.create!(tag_name: TagName.create!(name: 'pc_low'), category: :general)
+      mid = Tag.create!(tag_name: TagName.create!(name: 'pc_mid'), category: :general)
+      high = Tag.create!(tag_name: TagName.create!(name: 'pc_high'), category: :general)
+
+      low.update_columns(post_count: 1)
+      mid.update_columns(post_count: 3)
+      high.update_columns(post_count: 5)
+
+      get '/tags', params: {
+          name: 'pc_',
+          post_count_gte: 2,
+          post_count_lte: 4,
+          order: 'post_count:asc',
+      }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_names).to eq(['pc_mid'])
+    end
+
+    it 'filters tags by created_at range' do
+      old_tag = Tag.create!(tag_name: TagName.create!(name: 'created_old'), category: :general)
+      new_tag = Tag.create!(tag_name: TagName.create!(name: 'created_new'), category: :general)
+
+      old_time = Time.zone.local(2024, 1, 1, 0, 0, 0)
+      new_time = Time.zone.local(2024, 2, 1, 0, 0, 0)
+
+      old_tag.update_columns(created_at: old_time, updated_at: old_time)
+      new_tag.update_columns(created_at: new_time, updated_at: new_time)
+
+      get '/tags', params: {
+          name: 'created_',
+          created_from: Time.zone.local(2024, 1, 15, 0, 0, 0).iso8601,
+          order: 'created_at:asc',
+      }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_names).to eq(['created_new'])
+    end
+
+    it 'filters tags by updated_at range' do
+      old_tag = Tag.create!(tag_name: TagName.create!(name: 'updated_old'), category: :general)
+      new_tag = Tag.create!(tag_name: TagName.create!(name: 'updated_new'), category: :general)
+
+      old_time = Time.zone.local(2024, 3, 1, 0, 0, 0)
+      new_time = Time.zone.local(2024, 4, 1, 0, 0, 0)
+
+      old_tag.update_columns(created_at: old_time, updated_at: old_time)
+      new_tag.update_columns(created_at: new_time, updated_at: new_time)
+
+      get '/tags', params: {
+          name: 'updated_',
+          updated_to: Time.zone.local(2024, 3, 15, 0, 0, 0).iso8601,
+          order: 'updated_at:asc',
+      }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_names).to eq(['updated_old'])
+    end
+
+    it 'orders tags by custom category order' do
+      Tag.create!(tag_name: TagName.create!(name: 'cat_deerjikist'), category: :deerjikist)
+      Tag.create!(tag_name: TagName.create!(name: 'cat_meme'), category: :meme)
+      Tag.create!(tag_name: TagName.create!(name: 'cat_character'), category: :character)
+      Tag.create!(tag_name: TagName.create!(name: 'cat_general'), category: :general)
+      Tag.create!(tag_name: TagName.create!(name: 'cat_material'), category: :material)
+      Tag.create!(tag_name: TagName.create!(name: 'cat_meta'), category: :meta)
+      Tag.create!(tag_name: TagName.create!(name: 'nico:cat_nico'), category: :nico)
+
+      get '/tags', params: { name: 'cat_', order: 'category:asc', limit: 20 }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_names).to eq(%w[
+          cat_deerjikist
+          cat_meme
+          cat_character
+          cat_general
+          cat_material
+          cat_meta
+          nico:cat_nico
+      ])
+    end
+
+    it 'paginates and keeps total count' do
+      %w[pag_a pag_b pag_c].each do |name|
+        Tag.create!(tag_name: TagName.create!(name:), category: :general)
+      end
+
+      get '/tags', params: { name: 'pag_', order: 'name:asc', page: 2, limit: 2 }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(3)
+      expect(response_names).to eq(%w[pag_c])
+    end
+
+    it 'falls back to default ordering when order is invalid' do
+      low = Tag.create!(tag_name: TagName.create!(name: 'fallback_low'), category: :general)
+      high = Tag.create!(tag_name: TagName.create!(name: 'fallback_high'), category: :general)
+
+      low.update_columns(post_count: 1)
+      high.update_columns(post_count: 9)
+
+      get '/tags', params: { name: 'fallback_', order: 'nope:sideways' }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_names.first).to eq('fallback_high')
+    end
+
+    it 'normalises invalid page and limit' do
+      %w[norm_a norm_b].each do |name|
+        Tag.create!(tag_name: TagName.create!(name:), category: :general)
+      end
+
+      get '/tags', params: { name: 'norm_', order: 'name:asc', page: 0, limit: 0 }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(2)
+      expect(response_tags.size).to eq(1)
+      expect(response_names).to eq(['norm_a'])
     end
   end
 
@@ -39,7 +214,11 @@ RSpec.describe 'Tags API', type: :request do
         expect(json).to include(
             'id' => tag.id,
             'name' => 'spec_tag',
-            'category'  => 'general')
+            'category' => 'general',
+            'post_count' => 1,
+            'has_wiki' => false)
+        expect(json).to have_key('created_at')
+        expect(json).to have_key('updated_at')
       end
     end
 
@@ -61,7 +240,7 @@ RSpec.describe 'Tags API', type: :request do
 
       expect(json).to be_an(Array)
       expect(json.map { |t| t['name'] }).to include('spec_tag')
-      t = json.find { |t| t['name'] == 'spec_tag' }
+      t = json.find { |x| x['name'] == 'spec_tag' }
       expect(t).to have_key('matched_alias')
       expect(t['matched_alias']).to be(nil)
     end
@@ -73,9 +252,9 @@ RSpec.describe 'Tags API', type: :request do
 
       expect(json).to be_an(Array)
       expect(json.map { |t| t['name'] }).to include('spec_tag')
-      t = json.find { |t| t['name'] == 'spec_tag' }
+      t = json.find { |x| x['name'] == 'spec_tag' }
       expect(t['matched_alias']).to eq('unko')
-      expect(json.map { |t| t['name'] }).not_to include('unknown')
+      expect(json.map { |x| x['name'] }).not_to include('unknown')
     end
   end
 
@@ -85,10 +264,14 @@ RSpec.describe 'Tags API', type: :request do
 
       expect(response).to have_http_status(:ok)
 
-      expect(json).to have_key('id')
-      expect(json).to have_key('name')
-      expect(json['id']).to eq(tag.id)
-      expect(json['name']).to eq('spec_tag')
+      expect(json).to include(
+          'id' => tag.id,
+          'name' => 'spec_tag',
+          'category' => 'general',
+          'post_count' => 1,
+          'has_wiki' => false)
+      expect(json).to have_key('created_at')
+      expect(json).to have_key('updated_at')
     end
 
     it 'returns 404 when not found' do
@@ -97,7 +280,6 @@ RSpec.describe 'Tags API', type: :request do
     end
   end
 
-  # member? を持つ user を想定（Factory 側で trait 作ってもOK）
   let(:member_user) { create(:user) }
   let(:non_member_user) { create(:user) }
 
@@ -106,93 +288,226 @@ RSpec.describe 'Tags API', type: :request do
   end
 
   before do
-    allow(member_user).to receive(:member?).and_return(true)
-    allow(non_member_user).to receive(:member?).and_return(false)
+    allow(member_user).to receive(:gte_member?).and_return(true)
+    allow(non_member_user).to receive(:gte_member?).and_return(false)
   end
 
-  describe "PATCH /tags/:id" do
-    context "未ログイン" do
+  describe 'PATCH /tags/:id' do
+    context '未ログイン' do
       before { stub_current_user(nil) }
 
-      it "401 を返す" do
-        patch "/tags/#{tag.id}", params: { name: "new" }
+      it '401 を返す' do
+        patch "/tags/#{ tag.id }", params: { name: 'new' }
         expect(response).to have_http_status(:unauthorized)
       end
     end
 
-    context "ログインしてゐるが member でない" do
+    context 'ログインしてゐるが member でない' do
       before { stub_current_user(non_member_user) }
 
-      it "403 を返す" do
-        patch "/tags/#{tag.id}", params: { name: "new" }
+      it '403 を返す' do
+        patch "/tags/#{ tag.id }", params: { name: 'new' }
         expect(response).to have_http_status(:forbidden)
       end
     end
 
-    context "member" do
+    context 'member' do
       before { stub_current_user(member_user) }
 
-      it "name だけ更新できる" do
-        patch "/tags/#{tag.id}", params: { name: "new" }
+      it 'name だけ更新できる' do
+        patch "/tags/#{ tag.id }", params: { name: 'new' }
 
         expect(response).to have_http_status(:ok)
 
         tag.reload
-        expect(tag.name).to eq("new")
-        expect(tag.category).to eq("general")
+        expect(tag.name).to eq('new')
+        expect(tag.category).to eq('general')
 
-        json = JSON.parse(response.body)
-        expect(json["id"]).to eq(tag.id)
-        expect(json["name"]).to eq("new")
-        expect(json["category"]).to eq("general")
+        body = JSON.parse(response.body)
+        expect(body['id']).to eq(tag.id)
+        expect(body['name']).to eq('new')
+        expect(body['category']).to eq('general')
       end
 
-      it "category だけ更新できる" do
-        patch "/tags/#{tag.id}", params: { category: "meme" }
+      it 'category だけ更新できる' do
+        patch "/tags/#{ tag.id }", params: { category: 'meme' }
 
         expect(response).to have_http_status(:ok)
 
         tag.reload
-        expect(tag.name).to eq("spec_tag")
-        expect(tag.category).to eq("meme")
+        expect(tag.name).to eq('spec_tag')
+        expect(tag.category).to eq('meme')
       end
 
-      it "空文字は presence により無視され、更新は走らない（値が変わらない）" do
-        patch "/tags/#{tag.id}", params: { name: "", category: "   " }
+      it '空文字は presence により無視され、更新は走らない（値が変わらない）' do
+        patch "/tags/#{ tag.id }", params: { name: '', category: '   ' }
 
         expect(response).to have_http_status(:ok)
 
         tag.reload
-        expect(tag.name).to eq("spec_tag")
-        expect(tag.category).to eq("general")
+        expect(tag.name).to eq('spec_tag')
+        expect(tag.category).to eq('general')
       end
 
-      it "両方更新できる" do
-        patch "/tags/#{tag.id}", params: { name: "n", category: "meta" }
+      it '両方更新できる' do
+        patch "/tags/#{ tag.id }", params: { name: 'n', category: 'meta' }
 
         expect(response).to have_http_status(:ok)
 
         tag.reload
-        expect(tag.name).to eq("n")
-        expect(tag.category).to eq("meta")
+        expect(tag.name).to eq('n')
+        expect(tag.category).to eq('meta')
       end
 
-      it "存在しない id だと RecordNotFound になる（通常は 404）" do
-        # Rails 設定次第で例外がそのまま上がる/404になる
-        # APIなら rescue_from で 404 にしてることが多いので、その場合は 404 を期待。
-        patch "/tags/999999999", params: { name: "x" }
-
+      it '存在しない id だと RecordNotFound になる（通常は 404）' do
+        patch '/tags/999999999', params: { name: 'x' }
         expect(response.status).to be_in([404, 500])
       end
 
-      it "バリデーションで update! が失敗したら（通常は 422 か 500）" do
-        patch "/tags/#{tag.id}", params: { name: 'new', category: 'nico' }
-
-        # rescue_from の実装次第で変はる:
-        # - RecordInvalid を 422 にしてるなら 422
-        # - 未処理なら 500
+      it 'バリデーションで update! が失敗したら（通常は 422 か 500）' do
+        patch "/tags/#{ tag.id }", params: { name: 'new', category: 'nico' }
         expect(response.status).to be_in([422, 500])
       end
     end
   end
+
+  describe 'GET /tags/with-depth' do
+    let!(:root_meme) do
+      Tag.create!(tag_name: TagName.create!(name: 'depth_a_root_meme'), category: :meme)
+    end
+
+    let!(:root_material) do
+      Tag.create!(tag_name: TagName.create!(name: 'depth_b_root_material'), category: :material)
+    end
+
+    let!(:hidden_general_root) do
+      Tag.create!(tag_name: TagName.create!(name: 'depth_hidden_general_root'), category: :general)
+    end
+
+    let!(:child_character) do
+      Tag.create!(tag_name: TagName.create!(name: 'depth_child_character'), category: :character)
+    end
+
+    let!(:grandchild_material) do
+      Tag.create!(tag_name: TagName.create!(name: 'depth_grandchild_material'), category: :material)
+    end
+
+    let!(:child_general) do
+      Tag.create!(tag_name: TagName.create!(name: 'depth_child_general'), category: :general)
+    end
+
+    before do
+      TagImplication.create!(parent_tag: root_meme, tag: child_character)
+      TagImplication.create!(parent_tag: child_character, tag: grandchild_material)
+      TagImplication.create!(parent_tag: root_material, tag: child_general)
+    end
+
+    it 'returns only visible root tags and visible has_children flags' do
+      get '/tags/with-depth'
+
+      expect(response).to have_http_status(:ok)
+      expect(json.map { |t| t['name'] }).to eq([
+        'depth_a_root_meme',
+        'depth_b_root_material'
+      ])
+
+      meme_row = json.find { |t| t['name'] == 'depth_a_root_meme' }
+      material_row = json.find { |t| t['name'] == 'depth_b_root_material' }
+
+      expect(meme_row['has_children']).to eq(true)
+      expect(meme_row['children']).to eq([])
+
+      expect(material_row['has_children']).to eq(false)
+      expect(material_row['children']).to eq([])
+
+      expect(json.map { |t| t['name'] }).not_to include('depth_hidden_general_root')
+    end
+
+    it 'returns children of the specified parent' do
+      get '/tags/with-depth', params: { parent: root_meme.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json.map { |t| t['name'] }).to eq(['depth_child_character'])
+
+      row = json.first
+      expect(row['category']).to eq('character')
+      expect(row['has_children']).to eq(true)
+      expect(row['children']).to eq([])
+    end
+  end
+
+  describe 'GET /tags/name/:name/materials' do
+    let!(:material_user) { create_member_user! }
+
+    let!(:root_tag) do
+      Tag.create!(tag_name: TagName.create!(name: 'materials_root'), category: :material)
+    end
+
+    let!(:child_a_tag) do
+      Tag.create!(tag_name: TagName.create!(name: 'materials_child_a'), category: :material)
+    end
+
+    let!(:child_b_tag) do
+      Tag.create!(tag_name: TagName.create!(name: 'materials_child_b'), category: :character)
+    end
+
+    let!(:grandchild_tag) do
+      Tag.create!(tag_name: TagName.create!(name: 'materials_grandchild'), category: :material)
+    end
+
+    let!(:root_material) do
+      create_material(root_tag, user: material_user, filename: 'root.png')
+    end
+
+    let!(:child_a_material) do
+      create_material(child_a_tag, user: material_user, filename: 'child_a.png')
+    end
+
+    let!(:grandchild_material) do
+      create_material(grandchild_tag, user: material_user, filename: 'grandchild.png')
+    end
+
+    before do
+      TagImplication.create!(parent_tag: root_tag, tag: child_b_tag)
+      TagImplication.create!(parent_tag: root_tag, tag: child_a_tag)
+      TagImplication.create!(parent_tag: child_a_tag, tag: grandchild_tag)
+    end
+
+    it 'returns a tag tree with nested materials sorted by child name' do
+      get "/tags/name/#{ CGI.escape(root_tag.name) }/materials"
+
+      expect(response).to have_http_status(:ok)
+
+      expect(json).to include(
+        'id' => root_tag.id,
+        'name' => 'materials_root',
+        'category' => 'material'
+      )
+
+      expect(json['material']).to be_present
+      expect(json.dig('material', 'id')).to eq(root_material.id)
+      expect(json.dig('material', 'file')).to be_present
+      expect(json.dig('material', 'content_type')).to eq('image/png')
+
+      expect(json['children'].map { |t| t['name'] }).to eq([
+        'materials_child_a',
+        'materials_child_b'
+      ])
+
+      child_a = json['children'].find { |t| t['name'] == 'materials_child_a' }
+      child_b = json['children'].find { |t| t['name'] == 'materials_child_b' }
+
+      expect(child_a.dig('material', 'id')).to eq(child_a_material.id)
+      expect(child_a['children'].map { |t| t['name'] }).to eq(['materials_grandchild'])
+      expect(child_a.dig('children', 0, 'material', 'id')).to eq(grandchild_material.id)
+
+      expect(child_b['material']).to be_nil
+      expect(child_b['children']).to eq([])
+    end
+
+    it 'returns 404 when the tag does not exist' do
+      get '/tags/name/no_such_tag_12345/materials'
+      expect(response).to have_http_status(:not_found)
+    end
+  end
 end

backend/spec/requests/theatre_comments_spec.rb

@@ -0,0 +1,150 @@
+require 'rails_helper'
+
+RSpec.describe 'TheatreComments', type: :request do
+  def sign_in_as(user)
+    allow_any_instance_of(ApplicationController).to receive(:current_user).and_return(user)
+  end
+
+  describe 'GET /theatres/:theatre_id/comments' do
+    let(:theatre) { create(:theatre) }
+    let(:other_theatre) { create(:theatre) }
+    let(:alice) { create(:user, name: 'Alice') }
+    let(:bob) { create(:user, name: 'Bob') }
+
+    let!(:comment_3) do
+      create(
+        :theatre_comment,
+        theatre: theatre,
+        no: 3,
+        user: alice,
+        content: 'third comment'
+      )
+    end
+
+    let!(:comment_1) do
+      create(
+        :theatre_comment,
+        theatre: theatre,
+        no: 1,
+        user: alice,
+        content: 'first comment'
+      )
+    end
+
+    let!(:comment_2) do
+      create(
+        :theatre_comment,
+        theatre: theatre,
+        no: 2,
+        user: bob,
+        content: 'second comment'
+      )
+    end
+
+    let!(:other_comment) do
+      create(
+        :theatre_comment,
+        theatre: other_theatre,
+        no: 1,
+        user: bob,
+        content: 'other theatre comment'
+      )
+    end
+
+    it 'theatre_id で絞り込み、no_gt より大きいものを no 降順で返す' do
+      get "/theatres/#{theatre.id}/comments", params: { no_gt: 1 }
+
+      expect(response).to have_http_status(:ok)
+      expect(response.parsed_body.map { |row| row['no'] }).to eq([3, 2])
+      expect(response.parsed_body.map { |row| row['content'] }).to eq([
+        'third comment',
+        'second comment'
+      ])
+    end
+
+    it 'user は id と name だけを含む' do
+      get "/theatres/#{theatre.id}/comments", params: { no_gt: 1 }
+
+      expect(response).to have_http_status(:ok)
+
+      expect(response.parsed_body.first['user']).to eq({
+        'id' => alice.id,
+        'name' => 'Alice'
+      })
+      expect(response.parsed_body.first['user'].keys).to contain_exactly('id', 'name')
+    end
+
+    it 'no_gt が負数なら 0 として扱う' do
+      get "/theatres/#{theatre.id}/comments", params: { no_gt: -100 }
+
+      expect(response).to have_http_status(:ok)
+      expect(response.parsed_body.map { |row| row['no'] }).to eq([3, 2, 1])
+    end
+  end
+
+  describe 'POST /theatres/:theatre_id/comments' do
+    let(:user) { create(:user, name: 'Alice') }
+    let(:theatre) { create(:theatre, next_comment_no: 2) }
+
+    before do
+      create(
+        :theatre_comment,
+        theatre: theatre,
+        no: 1,
+        user: user,
+        content: 'existing comment'
+      )
+    end
+
+    it '未ログインなら 401 を返す' do
+      expect {
+        post "/theatres/#{theatre.id}/comments", params: { content: 'hello' }
+      }.not_to change(TheatreComment, :count)
+
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it 'content が blank なら 422 を返す' do
+      sign_in_as(user)
+
+      expect {
+        post "/theatres/#{theatre.id}/comments", params: { content: '   ' }
+      }.not_to change(TheatreComment, :count)
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+
+    it 'theatre が存在しなければ 404 を返す' do
+      sign_in_as(user)
+
+      expect {
+        post '/theatres/999999/comments', params: { content: 'hello' }
+      }.not_to change(TheatreComment, :count)
+
+      expect(response).to have_http_status(:not_found)
+    end
+
+    it 'コメントを作成し、user を紐づけ、next_comment_no を進める' do
+      sign_in_as(user)
+
+      expect {
+        post "/theatres/#{theatre.id}/comments", params: { content: 'new comment' }
+      }.to change(TheatreComment, :count).by(1)
+
+      expect(response).to have_http_status(:created)
+
+      comment = TheatreComment.find_by!(theatre: theatre, no: 2)
+
+      expect(comment.user).to eq(user)
+      expect(comment.content).to eq('new comment')
+      expect(theatre.reload.next_comment_no).to eq(3)
+
+      expect(response.parsed_body.slice('theatre_id', 'no', 'user_id', 'content')).to eq({
+        'theatre_id' => theatre.id,
+        'no' => 2,
+        'user_id' => user.id,
+        'content' => 'new comment'
+      })
+    end
+  end
+end

backend/spec/requests/theatres_spec.rb

@@ -0,0 +1,307 @@
+require 'rails_helper'
+require 'active_support/testing/time_helpers'
+
+
+RSpec.describe 'Theatres API', type: :request do
+  include ActiveSupport::Testing::TimeHelpers
+
+  around do |example|
+    travel_to(Time.zone.parse('2026-03-18 21:00:00')) do
+      example.run
+    end
+  end
+
+  let(:member) { create(:user, :member, name: 'member user') }
+  let(:other_user) { create(:user, :member, name: 'other user') }
+
+  let!(:youtube_post) do
+    Post.create!(
+      title: 'youtube post',
+      url: 'https://www.youtube.com/watch?v=spec123'
+    )
+  end
+
+  let!(:other_post) do
+    Post.create!(
+      title: 'other post',
+      url: 'https://example.com/posts/1'
+    )
+  end
+
+  let!(:theatre) do
+    Theatre.create!(
+      name: 'spec theatre',
+      opens_at: Time.zone.parse('2026-03-18 20:00:00'),
+      kind: 0,
+      created_by_user: member
+    )
+  end
+
+  describe 'GET /theatres/:id' do
+    subject(:do_request) do
+      get "/theatres/#{theatre_id}"
+    end
+
+    context 'when theatre exists' do
+      let(:theatre_id) { theatre.id }
+
+      it 'returns theatre json' do
+        do_request
+
+        expect(response).to have_http_status(:ok)
+        expect(json).to include(
+          'id' => theatre.id,
+          'name' => 'spec theatre'
+        )
+        expect(json).to have_key('opens_at')
+        expect(json).to have_key('closes_at')
+        expect(json).to have_key('created_at')
+        expect(json).to have_key('updated_at')
+
+        expect(json['created_by_user']).to include(
+          'id' => member.id,
+          'name' => 'member user'
+        )
+      end
+    end
+
+    context 'when theatre does not exist' do
+      let(:theatre_id) { 999_999_999 }
+
+      it 'returns 404' do
+        do_request
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+  end
+
+  describe 'PUT /theatres/:id/watching' do
+    subject(:do_request) do
+      put "/theatres/#{theatre_id}/watching"
+    end
+
+    let(:theatre_id) { theatre.id }
+
+    context 'when not logged in' do
+      it 'returns 401' do
+        sign_out
+        do_request
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when theatre does not exist' do
+      let(:theatre_id) { 999_999_999 }
+
+      it 'returns 404' do
+        sign_in_as(member)
+        do_request
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+
+    context 'when theatre has no host yet' do
+      before do
+        sign_in_as(member)
+      end
+
+      it 'creates watching row, assigns current user as host, and returns current theatre info' do
+        expect { do_request }
+          .to change { TheatreWatchingUser.count }.by(1)
+
+        expect(response).to have_http_status(:ok)
+
+        theatre.reload
+        watch = TheatreWatchingUser.find_by!(theatre: theatre, user: member)
+
+        expect(theatre.host_user_id).to eq(member.id)
+        expect(watch.expires_at).to be_within(1.second).of(30.seconds.from_now)
+
+        expect(json).to include(
+          'host_flg' => true,
+          'post_id' => nil,
+          'post_started_at' => nil
+        )
+
+        expect(json.fetch('watching_users')).to contain_exactly(
+          {
+            'id' => member.id,
+            'name' => 'member user'
+          }
+        )
+      end
+    end
+
+    context 'when current user is already watching' do
+      let!(:watching_row) do
+        TheatreWatchingUser.create!(
+          theatre: theatre,
+          user: member,
+          expires_at: 5.seconds.from_now
+        )
+      end
+
+      before do
+        sign_in_as(member)
+      end
+
+      it 'refreshes expires_at without creating another row' do
+        expect { do_request }
+          .not_to change { TheatreWatchingUser.count }
+
+        expect(response).to have_http_status(:ok)
+
+        expect(watching_row.reload.expires_at)
+          .to be_within(1.second).of(30.seconds.from_now)
+      end
+    end
+
+    context 'when another active host exists' do
+      before do
+        TheatreWatchingUser.create!(
+          theatre: theatre,
+          user: other_user,
+          expires_at: 10.minutes.from_now
+        )
+        theatre.update!(host_user: other_user)
+        sign_in_as(member)
+      end
+
+      it 'does not steal host and returns host_flg false' do
+        expect { do_request }
+          .to change { TheatreWatchingUser.count }.by(1)
+
+        expect(response).to have_http_status(:ok)
+        expect(theatre.reload.host_user_id).to eq(other_user.id)
+
+        expect(json).to include(
+          'host_flg' => false,
+          'post_id' => nil,
+          'post_started_at' => nil
+        )
+
+        expect(json.fetch('watching_users')).to contain_exactly(
+          {
+            'id' => member.id,
+            'name' => 'member user'
+          },
+          {
+            'id' => other_user.id,
+            'name' => 'other user'
+          }
+        )
+      end
+    end
+
+    context 'when host is set but no longer actively watching' do
+      let(:started_at) { 2.minutes.ago }
+
+      before do
+        TheatreWatchingUser.create!(
+          theatre: theatre,
+          user: other_user,
+          expires_at: 1.second.ago
+        )
+        theatre.update!(
+          host_user: other_user,
+          current_post: youtube_post,
+          current_post_started_at: started_at
+        )
+        sign_in_as(member)
+      end
+
+      it 'reassigns host to current user and returns current post info' do
+        expect { do_request }
+          .to change { TheatreWatchingUser.count }.by(1)
+
+        expect(response).to have_http_status(:ok)
+
+        theatre.reload
+        expect(theatre.host_user_id).to eq(member.id)
+
+        expect(json['host_flg']).to eq(true)
+        expect(json['post_id']).to eq(youtube_post.id)
+        expect(Time.zone.parse(json['post_started_at']))
+          .to be_within(1.second).of(started_at)
+      end
+    end
+  end
+
+  describe 'PATCH /theatres/:id/next_post' do
+    subject(:do_request) do
+      patch "/theatres/#{theatre_id}/next_post"
+    end
+
+    let(:theatre_id) { theatre.id }
+
+    context 'when not logged in' do
+      it 'returns 401' do
+        sign_out
+        do_request
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when theatre does not exist' do
+      let(:theatre_id) { 999_999_999 }
+
+      it 'returns 404' do
+        sign_in_as(member)
+        do_request
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+
+    context 'when logged in but not host' do
+      before do
+        theatre.update!(host_user: other_user)
+        sign_in_as(member)
+      end
+
+      it 'returns 403' do
+        do_request
+        expect(response).to have_http_status(:forbidden)
+      end
+    end
+
+    context 'when current user is host' do
+      before do
+        theatre.update!(host_user: member)
+        sign_in_as(member)
+      end
+
+      it 'sets current_post to an eligible post and updates current_post_started_at' do
+        expect { do_request }
+          .to change { theatre.reload.current_post_id }
+          .from(nil).to(youtube_post.id)
+
+        expect(response).to have_http_status(:no_content)
+        expect(theatre.reload.current_post_started_at)
+          .to be_within(1.second).of(Time.current)
+      end
+    end
+
+    context 'when current user is host and no eligible post exists' do
+      before do
+        youtube_post.destroy!
+        theatre.update!(
+          host_user: member,
+          current_post: other_post,
+          current_post_started_at: 1.hour.ago
+        )
+        sign_in_as(member)
+      end
+
+      it 'still returns 204 and clears current_post' do
+        do_request
+
+        expect(response).to have_http_status(:no_content)
+
+        theatre.reload
+        expect(theatre.current_post_id).to be_nil
+        expect(theatre.current_post_started_at)
+          .to be_within(1.second).of(Time.current)
+      end
+    end
+  end
+end

backend/spec/tasks/nico_sync_spec.rb

@@ -8,8 +8,8 @@ RSpec.describe "nico:sync" do
   end
 
   def create_tag!(name, category:)
-    tn = TagName.find_or_create_by!(name: name.to_s.strip)
-    Tag.find_or_create_by!(tag_name_id: tn.id) { |t| t.category = category }
+    tn = TagName.find_undiscard_or_create_by!(name: name.to_s.strip)
+    Tag.find_undiscard_or_create_by!(tag_name_id: tn.id) { |t| t.category = category }
   end
 
   def link_nico_to_tag!(nico_tag, tag)
@@ -90,4 +90,128 @@ RSpec.describe "nico:sync" do
     expect(active_names).to include("nico:NEW")
     expect(active_names).not_to include("nico:OLD")
   end
+
+  def snapshot_tags(post)
+    post.snapshot_tag_names.join(' ')
+  end
+
+  def create_post_version_for!(post, version_no: 1, event_type: 'create', created_by_user: nil)
+    PostVersion.create!(
+      post: post,
+      version_no: version_no,
+      event_type: event_type,
+      title: post.title,
+      url: post.url,
+      thumbnail_base: post.thumbnail_base,
+      tags: snapshot_tags(post),
+      parent: post.parent,
+      original_created_from: post.original_created_from,
+      original_created_before: post.original_created_before,
+      created_at: Time.current,
+      created_by_user: created_by_user
+    )
+  end
+
+  it '新規 post 作成時に version 1 を作る' do
+    Tag.bot
+    Tag.tagme
+    Tag.niconico
+    Tag.video
+    Tag.no_deerjikist
+
+    stub_python([{
+      'code' => 'sm9',
+      'title' => 't',
+      'tags' => ['AAA'],
+      'uploaded_at' => '2026-01-01 12:34:56'
+    }])
+
+    allow(URI).to receive(:open).and_return(StringIO.new('<html></html>'))
+
+    expect {
+      run_rake_task('nico:sync')
+    }.to change(PostVersion, :count).by(1)
+
+    post = Post.find_by!(url: 'https://www.nicovideo.jp/watch/sm9')
+    version = post.post_versions.order(:version_no).last
+
+    expect(version.version_no).to eq(1)
+    expect(version.event_type).to eq('create')
+    expect(version.created_by_user).to be_nil
+    expect(version.tags).to eq(snapshot_tags(post.reload))
+  end
+
+  it '既存 post の内容または tags が変わったとき update version を作る' do
+    post = Post.create!(
+      title: 'old',
+      url: 'https://www.nicovideo.jp/watch/sm9',
+      uploaded_user: nil
+    )
+
+    kept_general = create_tag!('spec_kept', category: 'general')
+    PostTag.create!(post: post, tag: kept_general)
+    create_post_version_for!(post)
+
+    linked = create_tag!('spec_linked', category: 'general')
+    nico = create_tag!('nico:AAA', category: 'nico')
+    link_nico_to_tag!(nico, linked)
+
+    Tag.bot
+    Tag.tagme
+    Tag.no_deerjikist
+
+    stub_python([{
+      'code' => 'sm9',
+      'title' => 't',
+      'tags' => ['AAA'],
+      'uploaded_at' => '2026-01-01 12:34:56'
+    }])
+
+    allow(URI).to receive(:open).and_return(StringIO.new('<html></html>'))
+
+    expect {
+      run_rake_task('nico:sync')
+    }.to change(PostVersion, :count).by(1)
+
+    version = post.reload.post_versions.order(:version_no).last
+    expect(version.version_no).to eq(2)
+    expect(version.event_type).to eq('update')
+    expect(version.created_by_user).to be_nil
+    expect(version.tags).to eq(snapshot_tags(post.reload))
+  end
+
+  it '既存 post に差分が無いときは新しい version を作らない' do
+    nico = create_tag!('nico:AAA', category: 'nico')
+    no_deerjikist = create_tag!('ニジラー情報不詳', category: 'meta')
+
+    post = Post.create!(
+      title: 't',
+      url: 'https://www.nicovideo.jp/watch/sm9',
+      uploaded_user: nil,
+      original_created_from: Time.iso8601('2026-01-01T03:34:00Z'),
+      original_created_before: Time.iso8601('2026-01-01T03:35:00Z')
+    )
+
+    PostTag.create!(post: post, tag: nico)
+    PostTag.create!(post: post, tag: no_deerjikist)
+    create_post_version_for!(post)
+
+    stub_python([{
+      'code' => 'sm9',
+      'title' => 't',
+      'tags' => ['AAA'],
+      'uploaded_at' => '2026-01-01 12:34:56'
+    }])
+
+    allow(URI).to receive(:open).and_return(StringIO.new('<html></html>'))
+
+    expect {
+      run_rake_task('nico:sync')
+    }.not_to change(PostVersion, :count)
+
+    version = post.reload.post_versions.order(:version_no).last
+    expect(version.version_no).to eq(1)
+    expect(version.event_type).to eq('create')
+    expect(version.tags).to eq(snapshot_tags(post.reload))
+  end
 end

frontend/package.json

@@ -15,6 +15,8 @@
     "@dnd-kit/modifiers": "^9.0.0",
     "@dnd-kit/utilities": "^3.2.2",
     "@fontsource-variable/noto-sans-jp": "^5.2.9",
+    "@mdx-js/react": "^3.1.1",
+    "@mdx-js/rollup": "^3.1.1",
     "@radix-ui/react-dialog": "^1.1.14",
     "@radix-ui/react-switch": "^1.2.5",
     "@radix-ui/react-toast": "^1.2.14",
@@ -37,13 +39,15 @@
     "react-youtube": "^10.1.0",
     "remark-gfm": "^4.0.1",
     "tailwind-merge": "^3.3.0",
-    "zustand": "^5.0.8",
-    "unist-util-visit-parents": "^6.0.1"
+    "unist-util-visit-parents": "^6.0.1",
+    "zustand": "^5.0.8"
   },
   "devDependencies": {
     "@eslint/js": "^9.25.0",
+    "@tailwindcss/typography": "^0.5.19",
     "@types/axios": "^0.14.4",
     "@types/markdown-it": "^14.1.2",
+    "@types/mdx": "^2.0.13",
     "@types/node": "^24.0.13",
     "@types/react": "^19.1.2",
     "@types/react-dom": "^19.1.2",

frontend/scripts/generate-sitemap.js

@@ -20,7 +20,7 @@ const fetchPosts = async tagName => (await axios.get (`${ API_BASE_URL }/posts`,
                                  match: 'all',
                                  limit: '20' }) } })).data.posts
 
-const fetchTags = async () => (await axios.get (`${ API_BASE_URL }/tags`)).data
+const fetchTags = async () => (await axios.get (`${ API_BASE_URL }/tags`)).data.tags
 const fetchTagNames = async () => (await fetchTags ()).map (tag => tag.name)
 
 const fetchWikiPages = async () => (await axios.get (`${ API_BASE_URL }/wiki`)).data

frontend/src/App.tsx

@@ -1,6 +1,4 @@
-import axios from 'axios'
-import toCamel from 'camelcase-keys'
-import { AnimatePresence, LayoutGroup } from 'framer-motion'
+import { AnimatePresence, LayoutGroup, motion } from 'framer-motion'
 import { useEffect, useState } from 'react'
 import { BrowserRouter,
 	 Navigate,
@@ -11,15 +9,25 @@ import { BrowserRouter,
 import RouteBlockerOverlay from '@/components/RouteBlockerOverlay'
 import TopNav from '@/components/TopNav'
 import { Toaster } from '@/components/ui/toaster'
-import { API_BASE_URL } from '@/config'
+import { apiPost, isApiError } from '@/lib/api'
+import MaterialBasePage from '@/pages/materials/MaterialBasePage'
+import MaterialDetailPage from '@/pages/materials/MaterialDetailPage'
+import MaterialListPage from '@/pages/materials/MaterialListPage'
+import MaterialNewPage from '@/pages/materials/MaterialNewPage'
+// import MaterialSearchPage from '@/pages/materials/MaterialSearchPage'
+import MorePage from '@/pages/MorePage'
 import NicoTagListPage from '@/pages/tags/NicoTagListPage'
 import NotFound from '@/pages/NotFound'
+import TOSPage from '@/pages/TOSPage.mdx'
 import PostDetailPage from '@/pages/posts/PostDetailPage'
 import PostHistoryPage from '@/pages/posts/PostHistoryPage'
 import PostListPage from '@/pages/posts/PostListPage'
 import PostNewPage from '@/pages/posts/PostNewPage'
+import PostSearchPage from '@/pages/posts/PostSearchPage'
 import ServiceUnavailable from '@/pages/ServiceUnavailable'
 import SettingPage from '@/pages/users/SettingPage'
+import TagListPage from '@/pages/tags/TagListPage'
+import TheatreDetailPage from '@/pages/theatres/TheatreDetailPage'
 import WikiDetailPage from '@/pages/wiki/WikiDetailPage'
 import WikiDiffPage from '@/pages/wiki/WikiDiffPage'
 import WikiEditPage from '@/pages/wiki/WikiEditPage'
@@ -38,15 +46,23 @@ const RouteTransitionWrapper = ({ user, setUser }: {
   const location = useLocation ()
 
   return (
-      <LayoutGroup id="gallery-shared">
       <AnimatePresence mode="wait">
-	  <Routes location={location} key={location.pathname}>
+	<Routes location={location}>
 	  <Route path="/" element={<Navigate to="/posts" replace/>}/>
 	  <Route path="/posts" element={<PostListPage/>}/>
 	  <Route path="/posts/new" element={<PostNewPage user={user}/>}/>
+	  <Route path="/posts/search" element={<PostSearchPage/>}/>
 	  <Route path="/posts/:id" element={<PostDetailRoute user={user}/>}/>
 	  <Route path="/posts/changes" element={<PostHistoryPage/>}/>
+	  <Route path="/tags" element={<TagListPage/>}/>
 	  <Route path="/tags/nico" element={<NicoTagListPage user={user}/>}/>
+	  <Route path="/theatres/:id" element={<TheatreDetailPage/>}/>
+	  <Route path="/materials" element={<MaterialBasePage/>}>
+	    <Route index element={<MaterialListPage/>}/>
+	    <Route path="new" element={<MaterialNewPage/>}/>
+	    <Route path=":id" element ={<MaterialDetailPage/>}/>
+	  </Route>
+	  {/* <Route path="/materials/search" element={<MaterialSearchPage/>}/> */}
 	  <Route path="/wiki" element={<WikiSearchPage/>}/>
 	  <Route path="/wiki/:title" element={<WikiDetailPage/>}/>
 	  <Route path="/wiki/new" element={<WikiNewPage user={user}/>}/>
@@ -55,10 +71,11 @@ const RouteTransitionWrapper = ({ user, setUser }: {
 	  <Route path="/wiki/changes" element={<WikiHistoryPage/>}/>
 	  <Route path="/users/settings" element={<SettingPage user={user} setUser={setUser}/>}/>
 	  <Route path="/settings" element={<Navigate to="/users/settings" replace/>}/>
+	  <Route path="/tos" element={<TOSPage/>}/>
+	  <Route path="/more" element={<MorePage/>}/>
 	  <Route path="*" element={<NotFound/>}/>
 	</Routes>
-	</AnimatePresence>
-      </LayoutGroup>)
+      </AnimatePresence>)
 }
 
 
@@ -75,12 +92,11 @@ export default (() => {
 
   useEffect (() => {
     const createUser = async () => {
-      const res = await axios.post (`${ API_BASE_URL }/users`)
-      const data = res.data as { code: string; user: any }
+      const data = await apiPost<{ code: string; user: User }> ('/users')
       if (data.code)
 	{
 	  localStorage.setItem ('user_code', data.code)
-	  setUser (toCamel (data.user, { deep: true }) as User)
+	  setUser (data.user)
 	}
     }
 
@@ -90,17 +106,16 @@ export default (() => {
 	void (async () => {
 	  try
 	  {
-	    const res = await axios.post (`${ API_BASE_URL }/users/verify`, { code })
-	    const data = res.data as { valid: boolean, user: any }
+	    const data = await apiPost<{ valid: boolean; user: User }> ('/users/verify', { code })
 	    if (data.valid)
-	      setUser (toCamel (data.user, { deep: true }))
+	      setUser (data.user)
 	    else
 	      await createUser ()
 	  }
 	  catch (err)
 	  {
-	    if (axios.isAxiosError (err))
-	      setStatus (err.status ?? 200)
+	    if (isApiError (err))
+	      setStatus (err.response?.status ?? 200)
 	  }
 	}) ()
       }
@@ -118,10 +133,15 @@ export default (() => {
       <>
 	<RouteBlockerOverlay/>
 	<BrowserRouter>
-	  <div className="flex flex-col h-screen w-screen">
+	  <LayoutGroup>
+	    <motion.div
+		layout="position"
+		transition={{ layout: { duration: .2, ease: 'easeOut' } }}
+		className="flex flex-col h-dvh w-full overflow-y-hidden">
 	      <TopNav user={user}/>
 	      <RouteTransitionWrapper user={user} setUser={setUser}/>
-	  </div>
+	    </motion.div>
+	  </LayoutGroup>
 	  <Toaster/>
 	</BrowserRouter>
       </>)

frontend/src/components/DraggableDroppableTagRow.tsx

@@ -1,5 +1,6 @@
 import { useDraggable, useDroppable } from '@dnd-kit/core'
 import { CSS } from '@dnd-kit/utilities'
+import { motion } from 'framer-motion'
 import { useRef } from 'react'
 
 import TagLink from '@/components/TagLink'
@@ -14,10 +15,11 @@ type Props = {
     nestLevel:        number
     pathKey:          string
     parentTagId?:     number
-    suppressClickRef: MutableRefObject<boolean> }
+    suppressClickRef: MutableRefObject<boolean>
+    sp?:              boolean }
 
 
-export default (({ tag, nestLevel, pathKey, parentTagId, suppressClickRef }: Props) => {
+export default (({ tag, nestLevel, pathKey, parentTagId, suppressClickRef, sp }: Props) => {
   const dndId = `tag-node:${ pathKey }`
 
   const downPosRef = useRef<{ x: number; y: number } | null> (null)
@@ -88,6 +90,10 @@ export default (({ tag, nestLevel, pathKey, parentTagId, suppressClickRef }: Pro
 	  className={cn ('rounded select-none', over && 'ring-2 ring-offset-2')}
 	  {...attributes}
 	  {...listeners}>
+	<motion.div
+	    transition={{ layout: { duration: .2, ease: 'easeOut' } }}
+	    layoutId={`tag-${ sp ? 'sp-' : '' }${ tag.id }`}>
 	  <TagLink tag={tag} nestLevel={nestLevel}/>
+	</motion.div>
       </div>)
 }) satisfies FC<Props>

frontend/src/components/MaterialSidebar.tsx

@@ -0,0 +1,97 @@
+import { Fragment, useEffect, useState } from 'react'
+
+import TagLink from '@/components/TagLink'
+import SidebarComponent from '@/components/layout/SidebarComponent'
+import { apiGet } from '@/lib/api'
+
+import type { FC, ReactNode } from 'react'
+
+import type { Tag } from '@/types'
+
+type TagWithDepth = Tag & {
+    hasChildren:  boolean
+    children:     TagWithDepth[] }
+
+
+const setChildrenById = (
+    tags:     TagWithDepth[],
+    targetId: number,
+    children: TagWithDepth[],
+): TagWithDepth[] => (
+    tags.map (tag => {
+      if (tag.id === targetId)
+	return { ...tag, children }
+
+      if (tag.children.length === 0)
+	return tag
+
+      return { ...tag,
+	       children: (setChildrenById (tag.children, targetId, children)
+			  .filter (t => t.category !== 'meme' || t.hasChildren)) }
+    }))
+
+
+export default (() => {
+  const [tags, setTags] = useState<TagWithDepth[]> ([])
+  const [openTags, setOpenTags] = useState<Record<number, boolean>> ({ })
+  const [tagFetchedFlags, setTagFetchedFlags] = useState<Record<number, boolean>> ({ })
+
+  useEffect (() => {
+    void (async () => {
+      setTags ((await apiGet<TagWithDepth[]> ('/tags/with-depth'))
+	       .filter (t => t.category !== 'meme' || t.hasChildren))
+    }) ()
+  }, [])
+
+  const renderTags = (ts: TagWithDepth[], nestLevel = 0): ReactNode => (
+      ts.map (t => (
+	  <Fragment key={t.id}>
+	    <li>
+	      <div className="flex">
+		<div className="flex-none w-4">
+		  {t.hasChildren && (
+		      <a
+			  href="#"
+			  onClick={async e => {
+			    e.preventDefault ()
+			    if (!(tagFetchedFlags[t.id]))
+			      {
+				try
+				{
+				  const data =
+				      await apiGet<TagWithDepth[]> (
+					  '/tags/with-depth', { params: { parent: String (t.id) } })
+				  setTags (prev => setChildrenById (prev, t.id, data))
+				  setTagFetchedFlags (prev => ({ ...prev, [t.id]: true }))
+				}
+				catch
+				{
+				  ;
+				}
+			      }
+			    setOpenTags (prev => ({ ...prev, [t.id]: !(prev[t.id]) }))
+			  }}>
+			{openTags[t.id] ? <>&minus;</> : '+'}
+		      </a>)}
+		</div>
+		<div className="flex-1 truncate">
+		  <TagLink
+		      tag={t}
+		      nestLevel={nestLevel}
+		      title={t.name}
+		      withCount={false}
+		      withWiki={false}
+		      to={`/materials?tag=${ encodeURIComponent (t.name) }`}/>
+		</div>
+	      </div>
+	    </li>
+	    {openTags[t.id] && renderTags (t.children, nestLevel + 1)}
+	  </Fragment>)))
+
+  return (
+      <SidebarComponent>
+	<ul>
+	  {renderTags (tags)}
+	</ul>
+      </SidebarComponent>)
+}) satisfies FC

frontend/src/components/NicoViewer.tsx

@@ -1,78 +1,204 @@
-import { useRef, useLayoutEffect, useEffect, useState } from 'react'
-type Props = { id:      string,
-	       width:   number,
-	       height:  number,
-	       style?:  CSSProperties }
+import { forwardRef,
+         useCallback,
+         useEffect,
+         useImperativeHandle,
+         useLayoutEffect,
+         useMemo,
+         useRef,
+         useState } from 'react'
 
-import type { CSSProperties, FC } from 'react'
+import type { CSSProperties, ForwardedRef } from 'react'
+
+import type { NiconicoMetadata, NiconicoVideoInfo, NiconicoViewerHandle } from '@/types'
+
+type NiconicoPlayerMessage =
+    | { eventName: 'enterProgrammaticFullScreen' }
+    | { eventName: 'exitProgrammaticFullScreen' }
+    | { eventName: 'loadComplete'; playerId?: string; data: { videoInfo: NiconicoVideoInfo } }
+    | { eventName: 'playerMetadataChange'; playerId?: string; data: NiconicoMetadata }
+    | { eventName: 'playerStatusChange' | 'statusChange'; playerId?: string; data?: unknown }
+    | { eventName: 'error'; playerId?: string; data?: unknown; code?: string; message?: string }
+
+type NiconicoCommand =
+    | { eventName: 'play'; sourceConnectorType: 1; playerId: string }
+    | { eventName: 'pause'; sourceConnectorType: 1; playerId: string }
+    | { eventName: 'seek'; sourceConnectorType: 1; playerId: string; data: { time: number } }
+    | { eventName: 'mute'; sourceConnectorType: 1; playerId: string; data: { mute: boolean } }
+    | { eventName: 'volumeChange'; sourceConnectorType: 1; playerId: string;
+	data: { volume: number } }
+    | { eventName: 'commentVisibilityChange'; sourceConnectorType: 1; playerId: string;
+	data: { commentVisibility: boolean } }
+
+const EMBED_ORIGIN = 'https://embed.nicovideo.jp'
+
+type Props = {
+    id:                 string
+    width:              number
+    height:             number
+    style?:             CSSProperties
+    onLoadComplete?:    (info: NiconicoVideoInfo) => void
+    onMetadataChange?:  (meta: NiconicoMetadata) => void }
 
 
-export default ((props: Props) => {
-  const { id, width, height, style = { } } = props
+export default forwardRef ((props: Props, ref: ForwardedRef<NiconicoViewerHandle>) => {
+  const { id, width, height, style = { }, onLoadComplete, onMetadataChange } = props
 
   const iframeRef = useRef<HTMLIFrameElement> (null)
+  const playerId = useMemo (() => `nico-${ id }-${ Math.random ().toString (36).slice (2) }`, [id])
 
   const [screenWidth, setScreenWidth] = useState<CSSProperties['width']> ()
   const [screenHeight, setScreenHeight] = useState<CSSProperties['height']> ()
   const [landscape, setLandscape] = useState<boolean> (false)
   const [fullScreen, setFullScreen] = useState<boolean> (false)
 
-  const src = `https://embed.nicovideo.jp/watch/${id}?persistence=1&oldScript=1&referer=&from=0&allowProgrammaticFullScreen=1`;
+  const src =
+      `${ EMBED_ORIGIN }/watch/${ id }`
+      + '?jsapi=1'
+      + `&playerId=${ encodeURIComponent (playerId) }`
+      + '&persistence=1'
+      + '&oldScript=1'
+      + '&referer='
+      + '&from=0'
+      + '&allowProgrammaticFullScreen=1'
 
-  const styleFullScreen: CSSProperties = fullScreen ? {
-      top:  0,
+  const styleFullScreen: CSSProperties =
+      fullScreen
+      ? { top: 0,
           left: landscape ? 0 : '100%',
           position: 'fixed',
           width: screenWidth,
           height: screenHeight,
-      zIndex: 2147483647,
+          zIndex: 2_147_483_647,
           maxWidth: 'none',
           transformOrigin: '0% 0%',
           transform: landscape ? 'none' : 'rotate(90deg)',
           WebkitTransformOrigin: '0% 0%',
-      WebkitTransform: landscape ? 'none' : 'rotate(90deg)' } : {};
+          WebkitTransform: landscape ? 'none' : 'rotate(90deg)' }
+      : { }
 
-  const margedStyle = {
-      border:   'none',
-      maxWidth: '100%',
-      ...style,
-      ...styleFullScreen }
+  const margedStyle: CSSProperties =
+      { border: 'none', maxWidth: '100%', ...style, ...styleFullScreen }
 
-  useEffect (() => {
-    const onMessage = (event: MessageEvent<any>) => {
-      if (!(iframeRef.current)
-	  || (event.source !== iframeRef.current.contentWindow))
+  const postToPlayer = useCallback ((message: NiconicoCommand) => {
+    const win = iframeRef.current?.contentWindow
+    if (!(win))
       return
 
-      if (event.data.eventName === 'enterProgrammaticFullScreen')
+    win.postMessage (message, EMBED_ORIGIN)
+  }, [])
+
+  const play = useCallback (() => {
+    postToPlayer ({ eventName: 'play', sourceConnectorType: 1, playerId })
+  }, [playerId, postToPlayer])
+
+  const pause = useCallback (() => {
+    postToPlayer ({ eventName: 'pause', sourceConnectorType: 1, playerId })
+  }, [playerId, postToPlayer])
+
+  const seek = useCallback ((time: number) => {
+    postToPlayer ({ eventName: 'seek', sourceConnectorType: 1, playerId, data: { time } })
+  }, [playerId, postToPlayer])
+
+  const mute = useCallback (() => {
+    postToPlayer ({ eventName: 'mute', sourceConnectorType: 1, playerId, data: { mute: true } })
+  }, [playerId, postToPlayer])
+
+  const unmute = useCallback (() => {
+    postToPlayer ({ eventName: 'mute', sourceConnectorType: 1, playerId, data: { mute: false } })
+  }, [playerId, postToPlayer])
+
+  const setVolume = useCallback ((volume: number) => {
+    postToPlayer (
+	{ eventName: 'volumeChange', sourceConnectorType: 1, playerId, data: { volume } })
+  }, [playerId, postToPlayer])
+
+  const showComments = useCallback (() => {
+    postToPlayer (
+	{ eventName: 'commentVisibilityChange', sourceConnectorType: 1, playerId,
+	  data: { commentVisibility: true } })
+  }, [playerId, postToPlayer])
+
+  const hideComments = useCallback (() => {
+    postToPlayer (
+	{ eventName: 'commentVisibilityChange', sourceConnectorType: 1, playerId,
+	  data: { commentVisibility: false } })
+  }, [playerId, postToPlayer])
+
+  useImperativeHandle (
+      ref,
+      () => ({ play, pause, seek, mute, unmute, setVolume, showComments, hideComments }),
+      [play, pause, seek, mute, unmute, setVolume, showComments, hideComments])
+
+  useEffect (() => {
+    const onMessage = (event: MessageEvent<NiconicoPlayerMessage>) => {
+      if (!(iframeRef.current)
+          || (event.source !== iframeRef.current.contentWindow)
+          || (event.origin !== EMBED_ORIGIN))
+        return
+
+      const data = event.data
+
+      if (!(data)
+	  || typeof data !== 'object'
+	  || !('eventName' in data))
+        return
+
+      if (('playerId' in data)
+	  && data.playerId
+	  && data.playerId !== playerId)
+        return
+
+      if (data.eventName === 'enterProgrammaticFullScreen')
+	{
 	  setFullScreen (true)
-      else if (event.data.eventName === 'exitProgrammaticFullScreen')
+	  return
+	}
+
+      if (data.eventName === 'exitProgrammaticFullScreen')
+	{
 	  setFullScreen (false)
+	  return
+	}
+
+      if (data.eventName === 'loadComplete')
+	{
+	  onLoadComplete?.(data.data.videoInfo)
+	  return
+	}
+
+      if (data.eventName === 'playerMetadataChange')
+	{
+	  onMetadataChange?.(data.data)
+	  return
+	}
+
+      if (data.eventName === 'error')
+        console.error ('niconico player error:', data)
     }
 
     addEventListener ('message', onMessage)
 
     return () => removeEventListener ('message', onMessage)
-  }, [])
+  }, [onLoadComplete, onMetadataChange, playerId])
 
-  useLayoutEffect(() => {
+  useLayoutEffect (() => {
     if (!(fullScreen))
       return
 
     const initialScrollX = scrollX
     const initialScrollY = scrollY
-    let timer: NodeJS.Timeout
+    let timer: ReturnType<typeof setTimeout>
     let ended = false
 
     const pollingResize = () => {
       if (ended)
         return
 
-      const landscape = innerWidth >= innerHeight
-      const windowWidth = `${landscape ? innerWidth : innerHeight}px`
-      const windowHeight = `${landscape ? innerHeight : innerWidth}px`
+      const isLandscape = innerWidth >= innerHeight
+      const windowWidth = `${ isLandscape ? innerWidth : innerHeight }px`
+      const windowHeight = `${ isLandscape ? innerHeight : innerWidth }px`
 
-      setLandscape (landscape)
+      setLandscape (isLandscape)
       setScreenWidth (windowWidth)
       setScreenHeight (windowHeight)
       timer = setTimeout (startPollingResize, 200)
@@ -97,15 +223,17 @@ export default ((props: Props) => {
   useEffect (() => {
     if (!(fullScreen))
       return
+
     scrollTo (0, 0)
   }, [screenWidth, screenHeight, fullScreen])
 
   return (
-      <iframe ref={iframeRef}
+      <iframe
+	  ref={iframeRef}
 	  src={src}
 	  width={width}
 	  height={height}
 	  style={margedStyle}
 	  allowFullScreen
 	  allow="autoplay"/>)
-}) satisfies FC<Props>
+})

frontend/src/components/PostEditForm.tsx

@@ -1,12 +1,10 @@
-import axios from 'axios'
-import toCamel from 'camelcase-keys'
 import { useEffect, useState } from 'react'
 
 import PostFormTagsArea from '@/components/PostFormTagsArea'
 import PostOriginalCreatedTimeField from '@/components/PostOriginalCreatedTimeField'
 import Label from '@/components/common/Label'
 import { Button } from '@/components/ui/button'
-import { API_BASE_URL } from '@/config'
+import { apiPut } from '@/lib/api'
 
 import type { FC } from 'react'
 
@@ -41,14 +39,11 @@ export default (({ post, onSave }: Props) => {
   const [tags, setTags] = useState<string> ('')
 
   const handleSubmit = async () => {
-    const res = await axios.put (
-	`${ API_BASE_URL }/posts/${ post.id }`,
-	{ title, tags,
-	  original_created_from: originalCreatedFrom,
+    const data = await apiPut<Post> (
+	`/posts/${ post.id }`,
+	{ title, tags, original_created_from: originalCreatedFrom,
 	  original_created_before: originalCreatedBefore },
-	{ headers: { 'Content-Type':     'multipart/form-data',
-		     'X-Transfer-Code':  localStorage.getItem ('user_code') ?? '' } })
-    const data = toCamel (res.data as any, { deep: true }) as Post
+	{ headers: { 'Content-Type': 'multipart/form-data' } })
     onSave ({ ...post,
 	      title:                  data.title,
 	      tags:                   data.tags,
@@ -67,7 +62,7 @@ export default (({ post, onSave }: Props) => {
 	  <Label>タイトル</Label>
 	  <input type="text"
 		 className="w-full border rounded p-2"
-		 value={title}
+		 value={title ?? ''}
 		 onChange={ev => setTitle (ev.target.value)}/>
 	</div>
 

frontend/src/components/PostEmbed.tsx

@@ -4,31 +4,60 @@ import YoutubeEmbed from 'react-youtube'
 import NicoViewer from '@/components/NicoViewer'
 import TwitterEmbed from '@/components/TwitterEmbed'
 
-import type { FC } from 'react'
+import type { FC, RefObject } from 'react'
 
-import type { Post } from '@/types'
+import type { NiconicoMetadata, NiconicoVideoInfo, NiconicoViewerHandle, Post } from '@/types'
 
-type Props = { post: Post }
+type Props = {
+    ref?:               RefObject<NiconicoViewerHandle | null>
+    post:               Post
+    onLoadComplete?:    (info: NiconicoVideoInfo) => void
+    onMetadataChange?:  (meta: NiconicoMetadata) => void }
 
 
-export default (({ post }: Props) => {
+export default (({ ref, post, onLoadComplete, onMetadataChange }: Props) => {
   const url = new URL (post.url)
 
   switch (url.hostname.split ('.').slice (-2).join ('.'))
   {
   case 'nicovideo.jp':
     {
-      const [videoId] = url.pathname.match (/(?<=\/watch\/)[a-zA-Z0-9]+?(?=\/|$)/)!
-      return <NicoViewer id={videoId} width={640} height={360}/>
+      const mVideoId = url.pathname.match (/(?<=\/watch\/)[a-zA-Z0-9]+?(?=\/|$)/)
+      if (!(mVideoId))
+	break
+
+      const [videoId] = mVideoId
+
+      return (
+	  <NicoViewer
+	      ref={ref}
+	      id={videoId}
+	      width={640}
+	      height={360}
+	      onLoadComplete={onLoadComplete}
+	      onMetadataChange={onMetadataChange}/>)
     }
+
   case 'twitter.com':
   case 'x.com':
-    const [userId] = url.pathname.match (/(?<=\/)[^\/]+?(?=\/|$|\?)/)!
-    const [statusId] = url.pathname.match (/(?<=\/status\/)\d+?(?=\/|$|\?)/)!
+    {
+      const mUserId = url.pathname.match (/(?<=\/)[^\/]+?(?=\/|$|\?)/)
+      const mStatusId = url.pathname.match (/(?<=\/status\/)\d+?(?=\/|$|\?)/)
+      if (!(mUserId) || !(mStatusId))
+	break
+
+      const [userId] = mUserId
+      const [statusId] = mStatusId
+
       return <TwitterEmbed userId={userId} statusId={statusId}/>
+    }
+
   case 'youtube.com':
     {
-      const videoId = url.searchParams.get ('v')!
+      const videoId = url.searchParams.get ('v')
+      if (!(videoId))
+	break
+
       return (
 	  <YoutubeEmbed videoId={videoId} opts={{ playerVars: {
 	      playsinline:  1,

frontend/src/components/PostFormTagsArea.tsx

@@ -1,11 +1,11 @@
-import axios from 'axios'
-import toCamel from 'camelcase-keys'
+// TODO: TagSearch と共通化する．
+
 import { useRef, useState } from 'react'
 
 import TagSearchBox from '@/components/TagSearchBox'
 import Label from '@/components/common/Label'
 import TextArea from '@/components/common/TextArea'
-import { API_BASE_URL } from '@/config'
+import { apiGet } from '@/lib/api'
 
 import type { FC, SyntheticEvent } from 'react'
 
@@ -27,8 +27,8 @@ const getTokenAt = (value: string, pos: number) => {
 }
 
 
-const replaceToken = (value: string, start: number, end: number, text: string) => (
-    `${ value.slice (0, start) }${ text }${ value.slice (end) }`)
+const replaceToken = (value: string, start: number, end: number, text: string) =>
+    `${ value.slice (0, start) }${ text }${ value.slice (end) }`
 
 
 type Props = {
@@ -40,16 +40,17 @@ export default (({ tags, setTags }: Props) => {
   const ref = useRef<HTMLTextAreaElement> (null)
 
   const [bounds, setBounds] = useState<{ start: number; end: number }> ({ start: 0, end: 0 })
+  const [focused, setFocused] = useState (false)
   const [suggestions, setSuggestions] = useState<Tag[]> ([])
   const [suggestionsVsbl, setSuggestionsVsbl] = useState (false)
 
   const handleTagSelect = (tag: Tag) => {
     setSuggestionsVsbl (false)
     const textarea = ref.current!
-    const newValue = replaceToken (tags, bounds.start, bounds.end, tag.name)
+    const newValue = replaceToken (tags, bounds.start, bounds.end, tag.name + ' ')
     setTags (newValue)
     requestAnimationFrame (async () => {
-      const p = bounds.start + tag.name.length
+      const p = bounds.start + tag.name.length + 1
       textarea.selectionStart = textarea.selectionEnd = p
       textarea.focus ()
       await recompute (p, newValue)
@@ -58,15 +59,21 @@ export default (({ tags, setTags }: Props) => {
 
   const recompute = async (pos: number, v: string = tags) => {
     const { start, end, token } = getTokenAt (v, pos)
+    if (!(token.trim ()))
+      {
+	setSuggestionsVsbl (false)
+	return
+      }
+
     setBounds ({ start, end })
-    const res = await axios.get (`${ API_BASE_URL }/tags/autocomplete`, { params: { q: token } })
-    const data = toCamel (res.data as any, { deep: true }) as Tag[]
+
+    const data = await apiGet<Tag[]> ('/tags/autocomplete', { params: { q: token, nico: '0' } })
     setSuggestions (data.filter (t => t.postCount > 0))
     setSuggestionsVsbl (suggestions.length > 0)
   }
 
   return (
-      <div>
+      <div className="relative w-full">
 	<Label>タグ</Label>
 	<TextArea
 	    ref={ref}
@@ -75,11 +82,18 @@ export default (({ tags, setTags }: Props) => {
 	    onSelect={async (ev: SyntheticEvent<HTMLTextAreaElement>) => {
 	      const pos = (ev.target as HTMLTextAreaElement).selectionStart
 	      await recompute (pos)
+	    }}
+	    onFocus={() => setFocused (true)}
+	    onBlur={() => {
+	      setFocused (false)
+	      setSuggestionsVsbl (false)
 	    }}/>
-	<TagSearchBox suggestions={suggestionsVsbl && suggestions.length
+	{focused && (
+	    <TagSearchBox
+		suggestions={suggestionsVsbl && suggestions.length > 0
 			     ? suggestions
 			     : [] as Tag[]}
 		activeIndex={-1}
-		      onSelect={handleTagSelect}/>
+		onSelect={handleTagSelect}/>)}
       </div>)
 }) satisfies FC<Props>

frontend/src/components/PostList.tsx

@@ -21,20 +21,18 @@ export default (({ posts, onClick }: Props) => {
   const cardRef = useRef<HTMLDivElement> (null)
 
   return (
-      <>
       <div className="flex flex-wrap gap-6 p-4">
 	{posts.map ((post, i) => {
-	    const id2 = `page-${ post.id }`
-	    const layoutId = id2
+	  const sharedId = `page-${ post.id }`
+	  const layoutId = sharedId
 
 	  return (
 	      <PrefetchLink
 		  to={`/posts/${ post.id }`}
 		  key={post.id}
 		  className="w-40 h-40"
-		    state={{ sharedId: `page-${ post.id }` }}
+		  state={{ sharedId }}
 		  onClick={e => {
-		      const sharedId = `page-${ post.id }`
 		    setForLocationKey (location.key, sharedId)
 		    onClick?.(e)
 		  }}>
@@ -45,20 +43,20 @@ export default (({ posts, onClick }: Props) => {
 			       transform-gpu will-change-transform"
 		    whileHover={{ scale: 1.02 }}
 		    onLayoutAnimationStart={() => {
-			if (cardRef.current)
-			  {
+		      if (!(cardRef.current))
+			return
+
 		      cardRef.current.style.position = 'relative'
 		      cardRef.current.style.zIndex = '9999'
-			  }
 		    }}
 		    onLayoutAnimationComplete={() => {
-			if (cardRef.current)
-			  {
+		      if (!(cardRef.current))
+			return 
+
 		      cardRef.current.style.zIndex = ''
 		      cardRef.current.style.position = ''
-			  }
 		    }}
-		      transition={{ type: 'spring', stiffness: 500, damping: 40, mass: .5 }}>
+		    transition={{ layout: { duration: .2, ease: 'easeOut' } }}>
 		  <img src={post.thumbnail || post.thumbnailBase || undefined}
 		       alt={post.title || post.url}
 		       title={post.title || post.url || undefined}
@@ -68,6 +66,5 @@ export default (({ posts, onClick }: Props) => {
 		</motion.div>
 	      </PrefetchLink>)
 	})}
-	</div>
-      </>)
+      </div>)
 }) satisfies FC<Props>

frontend/src/components/PostOriginalCreatedTimeField.tsx

@@ -1,5 +1,6 @@
 import DateTimeField from '@/components/common/DateTimeField'
 import Label from '@/components/common/Label'
+import { Button } from '@/components/ui/button'
 
 import type { FC } from 'react'
 
@@ -16,7 +17,8 @@ export default (({ originalCreatedFrom,
 		   setOriginalCreatedBefore }: Props) => (
     <div>
       <Label>オリジナルの作成日時</Label>
-      <div className="my-1">
+      <div className="my-1 flex">
+	<div className="w-80">
 	  <DateTimeField
 	      className="mr-2"
 	      value={originalCreatedFrom ?? undefined}
@@ -25,25 +27,42 @@ export default (({ originalCreatedFrom,
 		const v = ev.target.value
 		if (!(v))
 		  return
+
 		const d = new Date (v)
-	      if (d.getSeconds () === 0)
-		{
 		if (d.getMinutes () === 0 && d.getHours () === 0)
 		  d.setDate (d.getDate () + 1)
 		else
 		  d.setMinutes (d.getMinutes () + 1)
-		}
-	      else
-		d.setSeconds (d.getSeconds () + 1)
 		setOriginalCreatedBefore (d.toISOString ())
 	      }}/>
 	  以降
 	</div>
-      <div className="my-1">
+	<div>
+	  <Button
+	      className="bg-gray-600 text-white rounded"
+	      onClick={() => {
+		setOriginalCreatedFrom (null)
+	      }}>
+	    リセット
+	  </Button>
+	</div>
+      </div>
+      <div className="my-1 flex">
+	<div className="w-80">
 	  <DateTimeField
 	      className="mr-2"
 	      value={originalCreatedBefore ?? undefined}
 	      onChange={setOriginalCreatedBefore}/>
 	  より前
 	</div>
+	<div>
+	  <Button
+	      className="bg-gray-600 text-white rounded"
+	      onClick={() => {
+		setOriginalCreatedBefore (null)
+	      }}>
+	    リセット
+	  </Button>
+	</div>
+      </div>
     </div>)) satisfies FC<Props>

frontend/src/components/PrefetchLink.tsx

@@ -71,7 +71,8 @@ export default forwardRef<HTMLAnchorElement, Props> (({
 	  || ev.metaKey
 	  || ev.ctrlKey
 	  || ev.shiftKey
-	  || ev.altKey)
+	  || ev.altKey
+	  || (rest.target && rest.target !== '_self'))
 	return
 
       ev.preventDefault ()

frontend/src/components/SortHeader.tsx

@@ -0,0 +1,31 @@
+import { useLocation } from 'react-router-dom'
+
+import PrefetchLink from '@/components/PrefetchLink'
+
+
+export default <T extends string,>({ by, label, currentOrder, defaultDirection }: {
+    by:               T
+    label:            string
+    currentOrder:     `${ T }:${ 'asc' | 'desc' }`
+    defaultDirection: Record<T, 'asc' | 'desc'> }) => {
+  const [fld, dir] = currentOrder.split (':')
+
+  const location = useLocation ()
+  const qs = new URLSearchParams (location.search)
+  const nextDir =
+      (by === fld)
+      ? (dir === 'asc' ? 'desc' : 'asc')
+      : (defaultDirection[by] || 'desc')
+  qs.set ('order', `${ by }:${ nextDir }`)
+  qs.set ('page', '1')
+
+  return (
+      <PrefetchLink
+	  className="text-inherit visited:text-inherit hover:text-inherit"
+	  to={`${ location.pathname }?${ qs.toString () }`}>
+	<span className="font-bold">
+	  {label}
+	  {by === fld && (dir === 'asc' ? ' ▲' : ' ▼')}
+	</span>
+      </PrefetchLink>)
+}

frontend/src/components/TagDetailSidebar.tsx

@@ -6,21 +6,22 @@ import { DndContext,
 	 useSensor,
 	 useSensors } from '@dnd-kit/core'
 import { restrictToWindowEdges } from '@dnd-kit/modifiers'
-import axios from 'axios'
-import toCamel from 'camelcase-keys'
-import { AnimatePresence, motion } from 'framer-motion'
-import { useEffect, useRef, useState } from 'react'
-import { Link } from 'react-router-dom'
+import { useQueryClient } from '@tanstack/react-query'
+import { motion } from 'framer-motion'
+import { useEffect, useMemo, useRef, useState } from 'react'
 
 import DraggableDroppableTagRow from '@/components/DraggableDroppableTagRow'
+import PrefetchLink from '@/components/PrefetchLink'
 import TagLink from '@/components/TagLink'
 import TagSearch from '@/components/TagSearch'
 import SectionTitle from '@/components/common/SectionTitle'
 import SubsectionTitle from '@/components/common/SubsectionTitle'
 import SidebarComponent from '@/components/layout/SidebarComponent'
 import { toast } from '@/components/ui/use-toast'
-import { API_BASE_URL } from '@/config'
-import { CATEGORIES } from '@/consts'
+import { CATEGORIES, CATEGORY_NAMES } from '@/consts'
+import { apiDelete, apiGet, apiPatch, apiPost } from '@/lib/api'
+import { postsKeys, tagsKeys } from '@/lib/queryKeys'
+import { dateString, originalCreatedAtString } from '@/lib/utils'
 
 import type { DragEndEvent } from '@dnd-kit/core'
 import type { FC, MutableRefObject, ReactNode } from 'react'
@@ -36,28 +37,27 @@ const renderTagTree = (
     path:             string,
     suppressClickRef: MutableRefObject<boolean>,
     parentTagId?:     number,
+    sp?:              boolean,
 ): ReactNode[] => {
   const key = `${ path }-${ tag.id }`
 
   const self = (
-      <motion.li
-	  key={key}
-	  layout
-	  transition={{ duration: .2, ease: 'easeOut' }}
-	  className="mb-1">
+      <li key={key} className="mb-1">
 	<DraggableDroppableTagRow
 	    tag={tag}
 	    nestLevel={nestLevel}
 	    pathKey={key}
 	    parentTagId={parentTagId}
-	    suppressClickRef={suppressClickRef}/>
-      </motion.li>)
+	    suppressClickRef={suppressClickRef}
+	    sp={sp}/>
+      </li>)
 
   return [
       self,
       ...((tag.children
 	   ?.sort ((a, b) => a.name < b.name ? -1 : 1)
-	   .flatMap (child => renderTagTree (child, nestLevel + 1, key, suppressClickRef, tag.id)))
+	   .flatMap (child =>
+	      renderTagTree (child, nestLevel + 1, key, suppressClickRef, tag.id, sp)))
 	  ?? [])]
 }
 
@@ -132,10 +132,7 @@ const changeCategory = async (
     tagId:    number,
     category: Category,
 ): Promise<void> => {
-  await axios.patch (
-      `${ API_BASE_URL }/tags/${ tagId }`,
-      { category },
-      { headers: { 'X-Transfer-Code': localStorage.getItem ('user_code') ?? '' } })
+  await apiPatch (`/tags/${ tagId }`, { category })
 }
 
 
@@ -151,14 +148,34 @@ const DropSlot = ({ cat }: { cat: Category }) => {
 }
 
 
-type Props = { post: Post | null }
+type Props = { post: Post; sp?: boolean }
 
 
-export default (({ post }: Props) => {
+export default (({ post, sp }: Props) => {
+  sp = Boolean (sp)
+
+  const qc = useQueryClient ()
+
+  const baseTags = useMemo<TagByCategory> (() => {
+    const tagsTmp = { } as TagByCategory
+
+    for (const tag of post.tags)
+      {
+	if (!(tag.category in tagsTmp))
+	  tagsTmp[tag.category] = []
+	tagsTmp[tag.category].push (tag)
+      }
+
+    for (const cat of Object.keys (tagsTmp) as (keyof typeof tagsTmp)[])
+      tagsTmp[cat].sort ((tagA: Tag, tagB: Tag) => tagA.name < tagB.name ? -1 : 1)
+
+    return tagsTmp
+  }, [post])
+
   const [activeTagId, setActiveTagId] = useState<number | null> (null)
   const [dragging, setDragging] = useState (false)
   const [saving, setSaving] = useState (false)
-  const [tags, setTags] = useState ({ } as TagByCategory)
+  const [tags, setTags] = useState (baseTags)
 
   const suppressClickRef = useRef (false)
 
@@ -167,15 +184,9 @@ export default (({ post }: Props) => {
       useSensor (TouchSensor, { activationConstraint: { delay: 250, tolerance: 8 } }))
 
   const reloadTags = async (): Promise<void> => {
-    if (!(post))
-      return
-
-    const res = await axios.get (
-	`${ API_BASE_URL }/posts/${ post.id }`,
-	{ headers: { 'X-Transfer-Code': localStorage.getItem ('user_code') ?? '' } })
-    const data = toCamel (res.data as any, { deep: true }) as Post
-
-    setTags (buildTagByCategory (data))
+    setTags (buildTagByCategory (await apiGet<Post> (`/posts/${ post.id }`)))
+    qc.invalidateQueries ({ queryKey: postsKeys.root })
+    qc.invalidateQueries ({ queryKey: tagsKeys.root })
   }
 
   const onDragEnd = async (e: DragEndEvent) => {
@@ -216,16 +227,9 @@ export default (({ post }: Props) => {
 	    return
 
 	  if (fromParentId != null)
-	    {
-	      await axios.delete (
-		  `${ API_BASE_URL }/tags/${ fromParentId }/children/${ childId }`,
-		  { headers: { 'X-Transfer-Code': localStorage.getItem ('user_code') ?? '' } })
-	    }
+	    await apiDelete (`/tags/${ fromParentId }/children/${ childId }`)
 
-	  await axios.post (
-	      `${ API_BASE_URL }/tags/${ parentId }/children/${ childId }`,
-	      { },
-	      { headers: { 'X-Transfer-Code': localStorage.getItem ('user_code') ?? '' } })
+	  await apiPost (`/tags/${ parentId }/children/${ childId }`, { })
 
 	  await reloadTags ()
 	  toast ({
@@ -245,11 +249,7 @@ export default (({ post }: Props) => {
 	    await changeCategory (childId, cat)
 
 	  if (fromParentId != null)
-	    {
-	      await axios.delete (
-		  `${ API_BASE_URL }/tags/${ fromParentId }/children/${ childId }`,
-		  { headers: { 'X-Transfer-Code': localStorage.getItem ('user_code') ?? '' } })
-	    }
+	    await apiDelete (`/tags/${ fromParentId }/children/${ childId }`)
 
 	  const fromParent = fromParentId == null ? null : findTag (tags, fromParentId)
 
@@ -275,33 +275,9 @@ export default (({ post }: Props) => {
     }
   }
 
-  const categoryNames: Record<Category, string> = {
-      deerjikist: 'ニジラー',
-      meme:       '原作・ネタ元・ミーム等',
-      character:  'キャラクター',
-      general:    '一般',
-      material:   '素材',
-      meta:       'メタタグ',
-      nico:       'ニコニコタグ' }
-
   useEffect (() => {
-    if (!(post))
-      return
-
-    const tagsTmp = { } as TagByCategory
-
-    for (const tag of post.tags)
-      {
-	if (!(tag.category in tagsTmp))
-	  tagsTmp[tag.category] = []
-	tagsTmp[tag.category].push (tag)
-      }
-
-    for (const cat of Object.keys (tagsTmp) as (keyof typeof tagsTmp)[])
-      tagsTmp[cat].sort ((tagA: Tag, tagB: Tag) => tagA.name < tagB.name ? -1 : 1)
-
-    setTags (tagsTmp)
-  }, [post])
+    setTags (baseTags)
+  }, [baseTags])
 
   return (
       <SidebarComponent>
@@ -334,37 +310,39 @@ export default (({ post }: Props) => {
 	      document.body.style.userSelect = ''
 	    }}
 	    modifiers={[restrictToWindowEdges]}>
-	  <motion.div key={post?.id ?? 0} layout>
 	  {CATEGORIES.map ((cat: Category) => ((tags[cat] ?? []).length > 0 || dragging) && (
-		<motion.div layout className="my-3" key={cat}>
-		  <SubsectionTitle>{categoryNames[cat]}</SubsectionTitle>
+	      <div className="my-3" key={cat}>
+		<SubsectionTitle>
+		  <motion.div
+		      layoutId={`tag-${ sp ? 'sp-' : '' }${ cat }`}
+		      transition={{ layout: { duration: .2, ease: 'easeOut' } }}>
+		    {CATEGORY_NAMES[cat]}
+		  </motion.div>
+		</SubsectionTitle>
 
-		  <motion.ul layout>
-		    <AnimatePresence initial={false}>
+		<ul>
 		  {(tags[cat] ?? []).flatMap (tag => (
-			  renderTagTree (tag, 0, `cat-${ cat }`, suppressClickRef, undefined)))}
+		      renderTagTree (tag, 0, `cat-${ cat }`, suppressClickRef, undefined, sp)))}
 		  <DropSlot cat={cat}/>
-		    </AnimatePresence>
-		  </motion.ul>
-		</motion.div>))}
+		</ul>
+	      </div>))}
 	  {post && (
-		<div>
+	      <motion.div
+		  layoutId={`post-info-${ sp }`}
+		  transition={{ layout: { duration: .2, ease: 'easeOut' } }}>
 		<SectionTitle>情報</SectionTitle>
 		<ul>
 		  <li>Id.: {post.id}</li>
-		    {/* TODO: uploadedUser の取得を対応したらコメント外す */}
-		    {/*
 		  <li>
 		    <>耕作者: </>
 		    {post.uploadedUser
 		     ? (
-			  <Link to={`/users/${ post.uploadedUser.id }`}>
+			<PrefetchLink to={`/users/${ post.uploadedUser.id }`}>
 			  {post.uploadedUser.name || '名もなきニジラー'}
-			  </Link>)
+			</PrefetchLink>)
 		     : 'bot操作'}
 		  </li>
-		    */}
-		    <li>耕作日時: {(new Date (post.createdAt)).toLocaleString ()}</li>
+		  <li>耕作日時: {dateString (post.createdAt)}</li>
 		  <li>
 		    <>リンク: </>
 		    <a
@@ -376,24 +354,17 @@ export default (({ post }: Props) => {
 		    </a>
 		  </li>
 		  <li>
-		      {/* TODO: 表示形式きしょすぎるので何とかする */}
 		    <>オリジナルの投稿日時: </>
-		      {!(post.originalCreatedFrom) && !(post.originalCreatedBefore)
-		       ? '不明'
-		       : (
-			  <>
-			    {post.originalCreatedFrom
-			     && `${ (new Date (post.originalCreatedFrom)).toLocaleString () } 以降 `}
-			    {post.originalCreatedBefore
-			     && `${ (new Date (post.originalCreatedBefore)).toLocaleString () } より前`}
-			  </>)}
+		    {originalCreatedAtString (post.originalCreatedFrom,
+					      post.originalCreatedBefore)}
 		  </li>
 		  <li>
-		      <Link to={`/posts/changes?id=${ post.id }`}>履歴</Link>
+		    <PrefetchLink to={`/posts/changes?id=${ post.id }`}>
+		      履歴
+		    </PrefetchLink>
 		  </li>
 		</ul>
-		</div>)}
-	  </motion.div>
+	      </motion.div>)}
 
 	  <DragOverlay adjustScale={false}>
 	    <div className="pointer-events-none">

frontend/src/components/TagLink.tsx

@@ -1,9 +1,4 @@
-import axios from 'axios'
-import { useEffect, useState } from 'react'
-import { Link } from 'react-router-dom'
-
 import PrefetchLink from '@/components/PrefetchLink'
-import { API_BASE_URL } from '@/config'
 import { LIGHT_COLOUR_SHADE, DARK_COLOUR_SHADE, TAG_COLOUR } from '@/consts'
 import { cn } from '@/lib/utils'
 
@@ -11,19 +6,25 @@ import type { ComponentProps, FC, HTMLAttributes } from 'react'
 
 import type { Tag } from '@/types'
 
-type CommonProps = { tag:         Tag
+type CommonProps = { 
+    tag:        Tag
     nestLevel?: number
     withWiki?:  boolean
-		     withCount?:  boolean
-		     prefetch?:   boolean }
+    withCount?: boolean }
 
 type PropsWithLink =
-    CommonProps & { linkFlg?: true } & Partial<ComponentProps<typeof Link>>
+    & CommonProps
+    & { linkFlg?: true }
+    & Partial<ComponentProps<typeof PrefetchLink>>
 
 type PropsWithoutLink =
-    CommonProps & { linkFlg: false } & Partial<HTMLAttributes<HTMLSpanElement>>
+    & CommonProps
+    & { linkFlg: false }
+    & Partial<HTMLAttributes<HTMLSpanElement>>
 
-type Props = PropsWithLink | PropsWithoutLink
+type Props =
+    | PropsWithLink
+    | PropsWithoutLink
 
 
 export default (({ tag,
@@ -31,37 +32,7 @@ export default (({ tag,
 		   linkFlg   = true,
 		   withWiki  = true,
 		   withCount = true,
-		   prefetch  = false,
 		   ...props }: Props) => {
-  const [havingWiki, setHavingWiki] = useState (true)
-
-  const wikiExists = async (tag: Tag) => {
-    if ('hasWiki' in tag)
-      {
-	setHavingWiki (tag.hasWiki)
-	return
-      }
-
-    const tagName = (tag as Tag).name
-
-    try
-    {
-      await axios.get (`${ API_BASE_URL }/wiki/title/${ encodeURIComponent (tagName) }/exists`)
-      setHavingWiki (true)
-    }
-    catch
-    {
-      setHavingWiki (false)
-    }
-  }
-
-  useEffect (() => {
-    if (!(linkFlg) || !(withWiki))
-      return
-
-    wikiExists (tag)
-  }, [tag.name, linkFlg, withWiki])
-
   const spanClass = cn (
       `text-${ TAG_COLOUR[tag.category] }-${ LIGHT_COLOUR_SHADE }`,
       `dark:text-${ TAG_COLOUR[tag.category] }-${ DARK_COLOUR_SHADE }`)
@@ -74,19 +45,39 @@ export default (({ tag,
       <>
 	{(linkFlg && withWiki) && (
 	    <span className="mr-1">
-	      {havingWiki
+	      {(tag.materialId != null || tag.hasWiki)
 	       ? (
-		  <Link to={`/wiki/${ encodeURIComponent (tag.name) }`}
+		  tag.materialId == null
+		  ? (
+		      <PrefetchLink
+			  to={`/wiki/${ encodeURIComponent (tag.name) }`}
 			  className={linkClass}>
 			?
-		  </Link>)
+		      </PrefetchLink>)
 		  : (
-		  <Link to={`/wiki/${ encodeURIComponent (tag.name) }`}
+		      <PrefetchLink
+			  to={`/materials/${ tag.materialId }`}
+			  className={linkClass}>
+			?
+		      </PrefetchLink>))
+	       : (
+		  ['character', 'material'].includes (tag.category)
+		  ? (
+		      <PrefetchLink
+			  to={`/materials/new?tag=${ encodeURIComponent (tag.name) }`}
+			  className="animate-[wiki-blink_.25s_steps(2,end)_infinite]
+				     dark:animate-[wiki-blink-dark_.25s_steps(2,end)_infinite]"
+			  title={`${ tag.name } 素材情報が存在しません．`}>
+			!
+		      </PrefetchLink>)
+		  : (
+		      <PrefetchLink
+			  to={`/wiki/${ encodeURIComponent (tag.name) }`}
 			  className="animate-[wiki-blink_.25s_steps(2,end)_infinite]
 				     dark:animate-[wiki-blink-dark_.25s_steps(2,end)_infinite]"
 			  title={`${ tag.name } Wiki が存在しません．`}>
 			!
-		  </Link>)}
+		      </PrefetchLink>))}
 	    </span>)}
 	{nestLevel > 0 && (
 	    <span
@@ -103,19 +94,12 @@ export default (({ tag,
 	    </>)}
 	{linkFlg
 	 ? (
-	    prefetch
-	    ? <PrefetchLink
+	    <PrefetchLink
 		to={`/posts?${ (new URLSearchParams ({ tags: tag.name })).toString () }`}
 		className={linkClass}
 		{...props}>
 	      {tag.name}
-	      </PrefetchLink>
-	    : <Link
-		  to={`/posts?${ (new URLSearchParams ({ tags: tag.name })).toString () }`}
-		  className={linkClass}
-		  {...props}>
-		{tag.name}
-	      </Link>)
+	    </PrefetchLink>)
 	 : (
 	    <span className={spanClass}
 		  {...props}>

frontend/src/components/TagSearch.tsx

@@ -1,13 +1,13 @@
-import axios from 'axios'
-import toCamel from 'camelcase-keys'
-import React, { useEffect, useState } from 'react'
+// TODO: タグ入力系すべてに同様の処理あるため共通化する．
+
+import { useEffect, useState } from 'react'
 import { useNavigate, useLocation } from 'react-router-dom'
 
-import { API_BASE_URL } from '@/config'
+import { apiGet } from '@/lib/api'
 
 import TagSearchBox from './TagSearchBox'
 
-import type { FC } from 'react'
+import type { ChangeEvent, FC, KeyboardEvent } from 'react'
 
 import type { Tag } from '@/types'
 
@@ -21,7 +21,7 @@ export default (() => {
   const [suggestions, setSuggestions] = useState<Tag[]> ([])
   const [suggestionsVsbl, setSuggestionsVsbl] = useState (false)
 
-  const whenChanged = async (ev: React.ChangeEvent<HTMLInputElement>) => {
+  const whenChanged = async (ev: ChangeEvent<HTMLInputElement>) => {
     setSearch (ev.target.value)
 
     const q = ev.target.value.trim ().split (' ').at (-1)
@@ -31,14 +31,13 @@ export default (() => {
 	return
       }
 
-    const res = await axios.get (`${ API_BASE_URL }/tags/autocomplete`, { params: { q } })
-    const data = toCamel (res.data, { deep: true }) as Tag[]
+    const data = await apiGet<Tag[]> ('/tags/autocomplete', { params: { q } })
     setSuggestions (data.filter (t => t.postCount > 0))
     if (suggestions.length > 0)
       setSuggestionsVsbl (true)
   }
 
-  const handleKeyDown = (ev: React.KeyboardEvent<HTMLInputElement>) => {
+  const handleKeyDown = (ev: KeyboardEvent<HTMLInputElement>) => {
     switch (ev.key)
     {
     case 'ArrowDown':
@@ -57,8 +56,11 @@ export default (() => {
       if (activeIndex < 0)
 	break
       ev.preventDefault ()
+      {
 	const selected = suggestions[activeIndex]
-      selected && handleTagSelect (selected)
+	if (selected)
+	  handleTagSelect (selected)
+      }
       break
 
     case 'Escape':
@@ -68,14 +70,25 @@ export default (() => {
     }
     if (ev.key === 'Enter' && (!(suggestionsVsbl) || activeIndex < 0))
       {
-	navigate (`/posts?${ (new URLSearchParams ({ tags: search })).toString () }`)
+	const parts = search.split (' ')
+	const match = parts.map (t => t.toLowerCase ()).includes ('type:or') ? 'any' : 'all'
+	navigate (`/posts?${
+	    (new URLSearchParams ({
+		tags: parts.map (t => t.toLowerCase ())
+			   .filter (t => t !== 'type:or')
+			   .join (' '),
+		match }))
+	    .toString () }`)
 	setSuggestionsVsbl (false)
       }
   }
 
   const handleTagSelect = (tag: Tag) => {
     const parts = search.split (' ')
-    parts[parts.length - 1] = tag.name
+    parts[parts.length - 1] = (
+	(parts[parts.length - 1].slice(0, 4).toLowerCase () === 'not:')
+	? ('not:' + tag.name)
+	: tag.name)
     setSearch (parts.join (' ') + ' ')
     setSuggestions ([])
     setActiveIndex (-1)
@@ -83,7 +96,8 @@ export default (() => {
 
   useEffect (() => {
     const query = new URLSearchParams (location.search)
-    const tagsQuery = query.get ('tags') ?? ''
+    const anyFlg = query.get ('match') === 'any'
+    const tagsQuery = `${ query.get ('tags') ?? '' }${ anyFlg ? ' type:or' : '' }`
     setSearch (tagsQuery)
   }, [location.search])
 

frontend/src/components/TagSidebar.tsx

@@ -1,4 +1,3 @@
-import axios from 'axios'
 import { AnimatePresence, motion } from 'framer-motion'
 import { useEffect, useState } from 'react'
 import { useLocation, useNavigate } from 'react-router-dom'
@@ -7,8 +6,8 @@ import TagLink from '@/components/TagLink'
 import TagSearch from '@/components/TagSearch'
 import SectionTitle from '@/components/common/SectionTitle'
 import SidebarComponent from '@/components/layout/SidebarComponent'
-import { API_BASE_URL } from '@/config'
 import { CATEGORIES } from '@/consts'
+import { apiGet } from '@/lib/api'
 
 import type { FC, MouseEvent } from 'react'
 
@@ -66,21 +65,24 @@ export default (({ posts, onClick }: Props) => {
 	  {CATEGORIES.flatMap (cat => cat in tags ? (
 	      tags[cat].map (tag => (
 		  <li key={tag.id} className="mb-1">
-		    <TagLink tag={tag} prefetch onClick={onClick}/>
+		    <motion.div
+			transition={{ layout: { duration: .2, ease: 'easeOut' } }}
+			layoutId={`tag-${ tag.id }`}>
+		      <TagLink tag={tag} onClick={onClick}/>
+		    </motion.div>
 		  </li>))) : [])}
 	</ul>
 	<SectionTitle>関聯</SectionTitle>
-	{posts.length > 0 && (
 	<a href="#"
 	   onClick={ev => {
 	     ev.preventDefault ()
 	     void ((async () => {
 	       try
 	       {
-		     const { data } = await axios.get (`${ API_BASE_URL }/posts/random`,
+		 const data = await apiGet<Post> ('/posts/random',
 		     { params: { tags: tagsQuery.split (' ').filter (e => e !== '').join (' '),
 				 match: (anyFlg ? 'any' : 'all') } })
-		     navigate (`/posts/${ (data as Post).id }`)
+		 navigate (`/posts/${ data.id }`)
 	       }
 	       catch
 	       {
@@ -89,7 +91,7 @@ export default (({ posts, onClick }: Props) => {
 	     }) ())
 	   }}>
 	  ランダム
-	    </a>)}
+	</a>
       </>)
 
   return (
@@ -97,23 +99,19 @@ export default (({ posts, onClick }: Props) => {
 	<TagSearch/>
 
 	<div className="hidden md:block mt-4">
-	  {TagBlock}
+	  {posts.length > 0 && TagBlock}
 	</div>
 
 	<AnimatePresence initial={false}>
 	  {tagsVsbl && (
 	      <motion.div
 		  key="sptags"
-		  className="md:hidden mt-4"
-		  variants={{ hidden:   { clipPath: 'inset(0 0 100% 0)',
-					  height:   0 },
-			      visible:  { clipPath: 'inset(0 0 0% 0)',
-					  height:   'auto'} }}
-		  initial="hidden"
-		  animate="visible"
-		  exit="hidden"
+		  className="md:hidden overflow-hidden"
+		  initial={{ height: 0 }}
+		  animate={{ height: 'auto' }}
+		  exit={{ height: 0 }}
 		  transition={{ duration: .2, ease: 'easeOut' }}>
-		{TagBlock}
+		{posts.length > 0 && TagBlock}
 	      </motion.div>)}
 	</AnimatePresence>
 

frontend/src/components/TopNav.tsx

@@ -1,3 +1,4 @@
+import { useQuery } from '@tanstack/react-query'
 import { AnimatePresence, motion } from 'framer-motion'
 import { Fragment, useEffect, useLayoutEffect, useRef, useState } from 'react'
 import { useLocation } from 'react-router-dom'
@@ -6,61 +7,53 @@ import Separator from '@/components/MenuSeparator'
 import PrefetchLink from '@/components/PrefetchLink'
 import TopNavUser from '@/components/TopNavUser'
 import { WikiIdBus } from '@/lib/eventBus/WikiIdBus'
+import { tagsKeys, wikiKeys } from '@/lib/queryKeys'
 import { fetchTagByName } from '@/lib/tags'
 import { cn } from '@/lib/utils'
 import { fetchWikiPage } from '@/lib/wiki'
 
 import type { FC, MouseEvent } from 'react'
 
-import type { Menu, User } from '@/types'
+import type { Menu, MenuVisibleItem, Tag, User } from '@/types'
 
 type Props = { user: User | null }
 
 
-export default (({ user }: Props) => {
-  const location = useLocation ()
+export const menuOutline = ({ tag, wikiId, user, pathName }: { 
+    tag?: Tag | null
+    wikiId: number | null
+    user: User | null,
+    pathName: string }): Menu => {
+  const postCount = tag?.postCount ?? 0
 
-  const dirRef = useRef<(-1) | 1> (1)
-  const itemsRef = useRef<(HTMLAnchorElement | null)[]> ([])
-  const navRef = useRef<HTMLDivElement | null> (null)
+  const wikiPageFlg = Boolean (/^\/wiki\/(?!new|changes)[^\/]+/.test (pathName) && wikiId)
+  const wikiTitle = pathName.split ('/')[2] ?? ''
 
-  const measure = () => {
-    const nav = navRef.current
-    const el = itemsRef.current[activeIdx]
-    if (!(nav) || !(el) || activeIdx < 0)
-      return
-
-    const navRect = nav.getBoundingClientRect ()
-    const elRect = el.getBoundingClientRect ()
-
-    setHl ({ left:    elRect.left - navRect.left,
-	     width:   elRect.width,
-	     visible: true })
-  }
-
-  const [hl, setHl] = useState<{ left: number; width: number; visible: boolean }> ({
-      left:     0,
-      width:    0,
-      visible:  false })
-  const [menuOpen, setMenuOpen] = useState (false)
-  const [openItemIdx, setOpenItemIdx] = useState (-1)
-  const [postCount, setPostCount] = useState<number | null> (null)
-  const [wikiId, setWikiId] = useState<number | null> (WikiIdBus.get ())
-
-  const wikiPageFlg = Boolean (/^\/wiki\/(?!new|changes)[^\/]+/.test (location.pathname) && wikiId)
-  const wikiTitle = location.pathname.split ('/')[2]
-  const menu: Menu = [
+  return [
       { name: '広場', to: '/posts', subMenu: [
 	  { name: '一覧', to: '/posts' },
-	  { name: '投稿追加', to: '/posts/new' },
-	  { name: '耕作履歴', to: '/posts/changes' },
+	  { name: '検索', to: '/posts/search' },
+	  { name: '追加', to: '/posts/new' },
+	  { name: '履歴', to: '/posts/changes' },
 	  { name: 'ヘルプ', to: '/wiki/ヘルプ:広場' }] },
       { name: 'タグ', to: '/tags', subMenu: [
-	  { name: 'タグ一覧', to: '/tags', visible: false },
+	  { name: 'マスタ', to: '/tags' },
 	  { name: '別名タグ', to: '/tags/aliases', visible: false },
 	  { name: '上位タグ', to: '/tags/implications', visible: false },
 	  { name: 'ニコニコ連携', to: '/tags/nico' },
 	  { name: 'ヘルプ', to: '/wiki/ヘルプ:タグ' }] },
+      { name: '素材', to: '/materials', visible: false, subMenu: [
+	  { name: '一覧', to: '/materials' },
+	  { name: '検索', to: '/materials/search', visible: false }, 
+	  { name: '追加', to: '/materials/new' },
+	  { name: '履歴', to: '/materials/changes', visible: false },
+	  { name: 'ヘルプ', to: '/wiki/ヘルプ:素材集' }] },
+      { name: '上映会', to: '/theatres/1', base: '/theatres', subMenu: [
+	  { name: <>第&thinsp;1&thinsp;会場</>, to: '/theatres/1' },
+	  { name: 'CyTube', to: '//cytube.mm428.net/r/deernijika' },
+	  { name: <>ニジカ放送局第&thinsp;1&thinsp;チャンネル</>,
+	    to: '//www.youtube.com/watch?v=DCU3hL4Uu6A' },
+	  { name: 'ヘルプ', to: '/wiki/ヘルプ:上映会' }] },
       { name: 'Wiki', to: '/wiki/ヘルプ:ホーム', base: '/wiki', subMenu: [
 	  { name: '検索', to: '/wiki' },
 	  { name: '新規', to: '/wiki/new' },
@@ -71,12 +64,67 @@ export default (({ user }: Props) => {
 	    visible: wikiPageFlg },
 	  { name: '履歴', to: `/wiki/changes?id=${ wikiId }`, visible: wikiPageFlg },
 	  { name: '編輯', to: `/wiki/${ wikiId || wikiTitle }/edit`, visible: wikiPageFlg }] },
-      { name: 'ユーザ', to: '/users', subMenu: [
+      { name: 'ユーザ', to: '/users/settings', visible: false, subMenu: [
 	  { name: '一覧', to: '/users', visible: false },
 	  { name: 'お前', to: `/users/${ user?.id }`, visible: false },
-	  { name: '設定', to: '/users/settings', visible: Boolean (user) }] }]
+	  { name: '設定', to: '/users/settings', visible: Boolean (user) }] },
+      { name: '法規', visible: false, subMenu: [
+	  { name: '利用規約', to: '/tos' }] }]
+}
 
-  const activeIdx = menu.findIndex (item => location.pathname.startsWith (item.base || item.to))
+
+export default (({ user }: Props) => {
+  const location = useLocation ()
+
+  const dirRef = useRef<(-1) | 1> (1)
+  const itemsRef = useRef<(HTMLAnchorElement | null)[]> ([])
+  const navRef = useRef<HTMLDivElement | null> (null)
+
+  const measure = (idx: number) => {
+    const nav = navRef.current
+    const el = itemsRef.current[idx < 0 ? visibleMenu.length : idx]
+
+    if (!(nav) || !(el))
+      {
+	setHL ({ left: 0, width: 0, visible: true })
+	return
+      }
+
+    const navRect = nav.getBoundingClientRect ()
+    const elRect = el.getBoundingClientRect ()
+
+    setHL ({ left:    elRect.left - navRect.left,
+	     width:   elRect.width,
+	     visible: true })
+  }
+
+  const [hl, setHL] = useState<{ left: number; width: number; visible: boolean }> ({
+      left:     0,
+      width:    0,
+      visible:  false })
+  const [menuOpen, setMenuOpen] = useState (false)
+  const [moreVsbl, setMoreVsbl] = useState (false)
+  const [openItemIdx, setOpenItemIdx] = useState (-1)
+  const [wikiId, setWikiId] = useState<number | null> (WikiIdBus.get ())
+
+  const wikiIdStr = String (wikiId ?? '')
+
+  const { data: wikiPage } = useQuery ({
+      enabled: Boolean (wikiIdStr),
+      queryKey: wikiKeys.show (wikiIdStr, { }),
+      queryFn: () => fetchWikiPage (wikiIdStr, { }) })
+
+  const effectiveTitle = wikiPage?.title ?? ''
+
+  const { data: tag } = useQuery ({
+      enabled: Boolean (effectiveTitle),
+      queryKey: tagsKeys.show (effectiveTitle),
+      queryFn: () => fetchTagByName (effectiveTitle) })
+
+  const menu = menuOutline ({ tag, wikiId, user, pathName: location.pathname })
+  const visibleMenu = menu.filter ((item): item is MenuVisibleItem => item.visible ?? true)
+  const activeIdx =
+      visibleMenu.findIndex (item => location.pathname.startsWith (item.base || item.to))
 
   const prevActiveIdxRef = useRef<number> (activeIdx)
 
@@ -89,55 +137,31 @@ export default (({ user }: Props) => {
   const dir = dirRef.current
 
   useLayoutEffect (() => {
-    if (activeIdx < 0)
-      return
-
-    const raf = requestAnimationFrame (measure)
-    const onResize = () => requestAnimationFrame (measure)
+    const raf = requestAnimationFrame (() => measure (moreVsbl ? -1 : activeIdx))
+    const onResize = () => requestAnimationFrame (() => measure (moreVsbl ? -1 : activeIdx))
 
     addEventListener ('resize', onResize)
     return () => {
       cancelAnimationFrame (raf)
       removeEventListener ('resize', onResize)
     }
-  }, [activeIdx])
+  })
 
   useEffect (() => {
     const unsubscribe = WikiIdBus.subscribe (setWikiId)
     return () => unsubscribe ()
-  }, [])
+  }, [activeIdx])
 
   useEffect (() => {
     setMenuOpen (false)
-    setOpenItemIdx (menu.findIndex (item => (
-	location.pathname.startsWith (item.base || item.to))))
+    setOpenItemIdx (activeIdx)
   }, [location])
 
-  useEffect (() => {
-    if (!(wikiId))
-      return
-
-    const fetchPostCount = async () => {
-      try
-      {
-	const wikiPage = await fetchWikiPage (String (wikiId ?? ''))
-	const tag = await fetchTagByName (wikiPage.title)
-
-	setPostCount (tag.postCount)
-      }
-      catch
-      {
-	setPostCount (0)
-      }
-    }
-    fetchPostCount ()
-  }, [wikiId])
-
   return (
       <>
-	<nav className="px-3 flex justify-between items-center w-full min-h-[48px]
+	<nav className="px-3 flex justify-between items-center w-full
 			bg-yellow-200 dark:bg-red-975 md:bg-yellow-50">
-	  <div className="flex items-center gap-2 h-full">
+	  <div className="flex items-center gap-2 h-12">
 	    <PrefetchLink
 		to="/posts"
 		className="mx-4 text-xl font-bold text-pink-600 hover:text-pink-400
@@ -148,18 +172,25 @@ export default (({ user }: Props) => {
 	      ぼざクリ タグ広場
 	    </PrefetchLink>
 
-	    <div ref={navRef} className="relative hidden md:flex h-full items-center">
+	    <div ref={navRef} className="relative hidden md:flex h-12 items-center">
 	      <div aria-hidden
-		   className={cn ('absolute top-1/2 -translate-y-1/2 h-full',
+		   className={cn ('absolute inset-y-0 h-12',
 				  'bg-yellow-200 dark:bg-red-950',
 				  'transition-[transform,width] duration-200 ease-out')}
 		   style={{ width:      hl.width,
-			    transform:  `translate(${ hl.left }px, -50%)`,
+			    transform:  `translateX(${ hl.left }px)`,
 			    opacity:    hl.visible ? 1 : 0 }}/>
 
-	      {menu.map ((item, i) => (
+	      {visibleMenu.map ((item, i) => (
+		  <motion.div
+		      key={item.to}
+		      layoutId={`menu-${ item.name }`}
+		      animate={{ opacity: moreVsbl ? 0 : 1 }}
+		      transition={{ opacity: { duration: .12 },
+				    layout: { duration: .2, ease: 'easeOut' } }}
+		      style={{ pointerEvents: moreVsbl ? 'none' : 'auto' }}
+		      onMouseEnter={() => setMoreVsbl (false)}>
 		    <PrefetchLink
-		      key={i}
 			to={item.to}
 			ref={(el: (HTMLAnchorElement | null)) => {
 			  itemsRef.current[i] = el
@@ -167,7 +198,22 @@ export default (({ user }: Props) => {
 			className={cn ('relative z-10 flex h-full items-center px-5',
 				       (i === openItemIdx) && 'font-bold')}>
 		      {item.name}
-		  </PrefetchLink>))}
+		    </PrefetchLink>
+		  </motion.div>))}
+	      <PrefetchLink
+		  to="/more"
+		  ref={(el: (HTMLAnchorElement | null)) => {
+		    itemsRef.current[visibleMenu.length] = el
+		  }}
+		  onClick={() => setMoreVsbl (false)}
+		  onMouseEnter={() => {
+		    setMoreVsbl (true)
+		    measure (-1)
+		  }}
+		  className={cn ('relative z-10 flex h-full items-center px-5',
+				 (openItemIdx < 0 || moreVsbl) && 'font-bold')}>
+		その他 &raquo;
+	      </PrefetchLink>
 	    </div>
 	  </div>
 
@@ -185,8 +231,75 @@ export default (({ user }: Props) => {
 	  </a>
 	</nav>
 
-	<div className="relative hidden md:flex bg-yellow-200 dark:bg-red-950
-			items-center w-full min-h-[40px] overflow-hidden">
+	<AnimatePresence initial={false}>
+	  <motion.div
+	      key="submenu-shell"
+	      layout
+	      className="relative hidden md:block overflow-hidden
+			 bg-yellow-200 dark:bg-red-950"
+	      style={{ height: moreVsbl ? 40 * menu.length : (activeIdx < 0 ? 0 : 40) }}
+	      onMouseLeave={() => {
+		if (moreVsbl)
+		  setMoreVsbl (false)
+	      }}
+	      transition={{ layout: { duration: .2, ease: 'easeOut' } }}
+	      onAnimationComplete={() => {
+		measure (moreVsbl ? -1 : activeIdx)
+	      }}>
+	  {moreVsbl
+	   ? (
+	      menu.map ((item, i) => (
+		  <div key={i} className="relative h-[40px]">
+		    <div className="absolute inset-0 flex items-center px-3">
+		      <motion.div
+			  transition={{ duration: .2, ease: 'easeOut' }}
+			  {...((item.visible ?? true)
+			       ? { layoutId: `menu-${ item.name }` }
+			       : { initial: { x: 40, y: -40, opacity: 0 },
+				   animate: { x: 0, y: 0, opacity: 1 },
+				   exit: { x: 40, y: -40, opacity: 0 } })}
+			  className="z-10 h-full flex items-center px-3 font-bold w-24">
+			<h2>{item.name}</h2>
+		      </motion.div>
+		      {item.subMenu
+		       .filter (subItem => subItem.visible ?? true)
+		       .map ((subItem, j) => (
+			  'component' in subItem
+			  ? (
+			      <motion.div
+				  key={`c-${ i }-${ j }`}
+				  transition={{ duration: .2, ease: 'easeOut' }}
+				  {...((visibleMenu[activeIdx]?.name
+					=== item.name)
+				       ? { layoutId: `submenu-${ item.name }-${ j }` }
+				       : { initial: { y: -40, opacity: 0 },
+					   animate: { y: 0, opacity: 1 },
+					   exit: { y: -40, opacity: 0 } })}>
+				{subItem.component}
+			      </motion.div>)
+			  : (
+			      <motion.div
+				  key={`l-${ i }-${ j }`}
+				  transition={{ duration: .2, ease: 'easeOut' }}
+				  {...((visibleMenu[activeIdx]?.name
+					=== item.name)
+				       ? { layoutId: `submenu-${ item.name }-${ j }` }
+				       : { initial: { y: -40, opacity: 0 },
+					   animate: { y: 0, opacity: 1 },
+					   exit: { y: -40, opacity: 0 } })}>
+				<PrefetchLink
+				    to={subItem.to}
+				    target={subItem.to.slice (0, 2) === '//' ? '_blank' : undefined}
+				    onClick={() => setMoreVsbl (false)}
+				    className="h-full flex items-center px-3">
+				  {subItem.name}
+				</PrefetchLink>
+			      </motion.div>)))}
+		    </div>
+		  </div>)))
+	   : ((visibleMenu[activeIdx]?.subMenu ?? []).length > 0
+	      && (
+		  <div className="relative h-[40px]">
 		    <AnimatePresence initial={false} custom={dir}>
 		      <motion.div
 			  key={activeIdx}
@@ -199,21 +312,34 @@ export default (({ user }: Props) => {
 			  animate="centre"
 			  exit="exit"
 			  transition={{ duration: .2, ease: 'easeOut' }}>
-	      {(menu[activeIdx]?.subMenu ?? [])
+			{(visibleMenu[activeIdx]?.subMenu ?? [])
 			 .filter (item => item.visible ?? true)
 			 .map ((item, i) => (
 			    'component' in item
-		  ? <Fragment key={`c-${ i }`}>{item.component}</Fragment>
+			    ? (
+				<motion.div
+				    key={`c-${ i }`}
+				    transition={{ layout: { duration: .2, ease: 'easeOut' } }}
+				    layoutId={`submenu-${ visibleMenu[activeIdx].name }-${ i }`}>
+				  {item.component}
+				</motion.div>)
 			    : (
-		      <PrefetchLink
+				<motion.div
 				    key={`l-${ i }`}
+				    transition={{ layout: { duration: .2, ease: 'easeOut' } }}
+				    layoutId={`submenu-${ visibleMenu[activeIdx].name }-${ i }`}>
+				  <PrefetchLink
 				      to={item.to}
+				      target={item.to.slice (0, 2) === '//' ? '_blank' : undefined}
 				      className="h-full flex items-center px-3">
 				    {item.name}
-		      </PrefetchLink>)))}
+				  </PrefetchLink>
+				</motion.div>)))}
+		      </motion.div>
+		    </AnimatePresence>
+		  </div>))}
 	  </motion.div>
 	</AnimatePresence>
-	</div>
 
 	<AnimatePresence initial={false}>
 	  {menuOpen && (
@@ -230,7 +356,7 @@ export default (({ user }: Props) => {
 		  exit="closed"
 		  transition={{ duration: .2, ease: 'easeOut' }}>
 		<Separator/>
-		{menu.map ((item, i) => (
+		{visibleMenu.map ((item, i) => (
 		    <Fragment key={i}>
 		      <PrefetchLink
 			  to={i === openItemIdx ? item.to : '#'}
@@ -274,12 +400,25 @@ export default (({ user }: Props) => {
 				      <PrefetchLink
 					  key={`sp-l-${ i }-${ j }`}
 					  to={subItem.to}
+					  target={subItem.to.slice (0, 2) === '//'
+						  ? '_blank'
+						  : undefined}
 					  className="w-full min-h-[36px] flex items-center pl-12">
 					{subItem.name}
 				      </PrefetchLink>)))}
 			    </motion.div>)}
 		      </AnimatePresence>
 		    </Fragment>))}
+		<PrefetchLink
+		    to="/more"
+		    ref={(el: (HTMLAnchorElement | null)) => {
+		      itemsRef.current[visibleMenu.length] = el
+		    }}
+		    className={cn ('w-full min-h-[40px] flex items-center pl-8',
+				   ((openItemIdx < 0)
+				    && 'font-bold bg-yellow-50 dark:bg-red-950'))}>
+		  その他 &raquo;
+		</PrefetchLink>
 		<TopNavUser user={user} sp/>
 		<Separator/>
 	      </motion.div>)}

frontend/src/components/TopNavUser.tsx

@@ -1,6 +1,5 @@
-import { Link } from 'react-router-dom'
-
 import Separator from '@/components/MenuSeparator'
+import PrefetchLink from '@/components/PrefetchLink'
 import { cn } from '@/lib/utils'
 
 import type { FC } from 'react'
@@ -24,9 +23,9 @@ export default (({ user, sp }: Props) => {
   return (
       <>
 	{sp && <Separator/>}
-	<Link to="/users/settings"
+	<PrefetchLink to="/users/settings"
 	      className={className}>
 	  {user.name || '名もなきニジラー'}
-	</Link>
+	</PrefetchLink>
       </>)
 }) satisfies FC<Props>

frontend/src/components/WikiBody.tsx

@@ -1,30 +1,22 @@
-import axios from 'axios'
-import toCamel from 'camelcase-keys'
-import { useEffect, useMemo, useState } from 'react'
+import { useQuery } from '@tanstack/react-query'
+import { useMemo } from 'react'
 import ReactMarkdown from 'react-markdown'
-import { Link } from 'react-router-dom'
 import remarkGFM from 'remark-gfm'
 
-import SectionTitle from '@/components/common/SectionTitle'
-import SubsectionTitle from '@/components/common/SubsectionTitle'
-import { API_BASE_URL } from '@/config'
+import PrefetchLink from '@/components/PrefetchLink'
+import { wikiKeys } from '@/lib/queryKeys'
 import remarkWikiAutoLink from '@/lib/remark-wiki-autolink'
+import { fetchWikiPages } from '@/lib/wiki'
 
 import type { FC } from 'react'
 import type { Components } from 'react-markdown'
 
-import type { WikiPage } from '@/types'
-
 type Props = { title: string
 	       body?: string }
 
-const mdComponents = { h1:  ({ children }) => <SectionTitle>{children}</SectionTitle>,
-		       h2:  ({ children }) => <SubsectionTitle>{children}</SubsectionTitle>,
-		       ol:  ({ children }) => <ol className="list-decimal pl-6">{children}</ol>,
-		       ul:  ({ children }) => <ul className="list-disc pl-6">{children}</ul>,
-		       a:   (({ href, children }) => (
+const mdComponents = { a: (({ href, children }) => (
 			      ['/', '.'].some (e => href?.startsWith (e))
-			        ? <Link to={href!}>{children}</Link>
+			      ? <PrefetchLink to={href!}>{children}</PrefetchLink>
 			      : (
 				  <a href={href}
 				     target="_blank"
@@ -34,26 +26,15 @@ const mdComponents = { h1:  ({ children }) => <SectionTitle>{children}</SectionT
 
 
 export default (({ title, body }: Props) => {
-  const [pageNames, setPageNames] = useState<string[]> ([])
+  const { data } = useQuery ({
+      enabled: Boolean (body),
+      queryKey: wikiKeys.index ({ }),
+      queryFn: () => fetchWikiPages ({ }) })
+  const pageNames = (data ?? []).map (page => page.title).sort ((a, b) => b.length - a.length)
 
   const remarkPlugins = useMemo (
       () => [() => remarkWikiAutoLink (pageNames), remarkGFM], [pageNames])
 
-  useEffect (() => {
-    void (async () => {
-      try
-      {
-	const res = await axios.get (`${ API_BASE_URL }/wiki`)
-	const data: WikiPage[] = toCamel (res.data as any, { deep: true })
-	setPageNames (data.map (page => page.title).sort ((a, b) => b.length - a.length))
-      }
-      catch
-      {
-	setPageNames ([])
-      }
-    }) ()
-  }, [])
-
   return (
       <ReactMarkdown components={mdComponents} remarkPlugins={remarkPlugins}>
 	{body || `このページは存在しません。[新規作成してください](/wiki/new?title=${ encodeURIComponent (title) })。`}

frontend/src/components/common/DateTimeField.tsx

@@ -5,7 +5,7 @@ import { cn } from '@/lib/utils'
 import type { FC, FocusEvent } from 'react'
 
 
-const pad = (n: number) => n.toString ().padStart (2, '0')
+const pad = (n: number): string => n.toString ().padStart (2, '0')
 
 
 const toDateTimeLocalValue = (d: Date) => {
@@ -14,8 +14,7 @@ const toDateTimeLocalValue = (d: Date) => {
   const day = pad (d.getDate ())
   const h = pad (d.getHours ())
   const min = pad (d.getMinutes ())
-  const s = pad (d.getSeconds ())
-  return `${ y }-${ m }-${ day }T${ h }:${ min }:${ s }`
+  return `${ y }-${ m }-${ day }T${ h }:${ min }:00`
 }
 
 
@@ -37,7 +36,6 @@ export default (({ value, onChange, className, onBlur }: Props) => {
       <input
 	  className={cn ('border rounded p-2', className)}
 	  type="datetime-local"
-	  step={1}
 	  value={local}
 	  onChange={ev => {
 	    const v = ev.target.value

frontend/src/components/common/Pagination.tsx

@@ -48,7 +48,7 @@ const getPages = (
 }
 
 
-export default (({ page, totalPages, siblingCount = 4 }) => {
+export default (({ page, totalPages, siblingCount = 3 }) => {
   const location = useLocation ()
 
   const buildTo = (p: number) => {
@@ -63,19 +63,65 @@ export default (({ page, totalPages, siblingCount = 4 }) => {
       <nav className="mt-4 flex justify-center" aria-label="Pagination">
 	<div className="flex items-center gap-2">
 	  {(page > 1)
-	   ? <PrefetchLink to={buildTo (page - 1)} aria-label="前のページ">&lt;</PrefetchLink>
-	   : <span aria-hidden>&lt;</span>}
+	   ? (
+	      <>
+		<PrefetchLink
+		    className="md:hidden p-2"
+		    to={buildTo (1)}
+		    aria-label="最初のページ">
+		  |&lt;
+		</PrefetchLink>
+		<PrefetchLink
+		    className="p-2"
+		    to={buildTo (page - 1)}
+		    aria-label="前のページ">
+		  &lt;
+		</PrefetchLink>
+	      </>)
+	   : (
+	      <>
+		<span className="md:hidden p-2" aria-hidden>
+		  |&lt;
+		</span>
+		<span className="p-2" aria-hidden>
+		  &lt;
+		</span>
+	      </>)}
 
 	  {pages.map ((p, idx) => (
 	      (p === '…')
-	      ? <span key={`dots-${ idx }`}>…</span>
+	      ? <span key={`dots-${ idx }`} className="hidden md:block p-2">…</span>
 	      : ((p === page)
-		 ? <span key={p} className="font-bold" aria-current="page">{p}</span>
-		 : <PrefetchLink key={p} to={buildTo (p)}>{p}</PrefetchLink>)))}
+		 ? <span key={p} className="font-bold p-2" aria-current="page">{p}</span>
+		 : (
+		    <PrefetchLink
+			key={p}
+			className="hidden md:block p-2"
+			to={buildTo (p)}>
+		      {p}
+		    </PrefetchLink>))))}
 
 	  {(page < totalPages)
-	   ? <PrefetchLink to={buildTo (page + 1)} aria-label="次のページ">&gt;</PrefetchLink>
-	   : <span aria-hidden>&gt;</span>}
+	   ? (
+	      <>
+		<PrefetchLink
+		    className="p-2"
+		    to={buildTo (page + 1)}
+		    aria-label="次のページ">
+		  &gt;
+		</PrefetchLink>
+		<PrefetchLink
+		    className="md:hidden p-2"
+		    to={buildTo (totalPages)}
+		    aria-label="最後のページ">
+		  &gt;|
+		</PrefetchLink>
+	      </>)
+	   : (
+	      <>
+		<span className="p-2" aria-hidden>&gt;</span>
+		<span className="md:hidden p-2" aria-hidden>&gt;|</span>
+	      </>)}
 	</div>
       </nav>)
 }) satisfies FC<Props>

frontend/src/components/common/SectionTitle.tsx

@@ -1,9 +1,11 @@
-import React from 'react'
+import { cn } from '@/lib/utils'
 
-type Props = { children: React.ReactNode }
+import type { ComponentPropsWithoutRef, FC } from 'react'
+
+type Props = ComponentPropsWithoutRef<'h2'>
 
 
-export default ({ children }: Props) => (
-    <h2 className="text-xl my-4">
+export default (({ children, className, ...rest }: Props) => (
+    <h2 {...rest} className={cn ('text-xl my-4', className)}>
       {children}
-    </h2>)
+    </h2>)) satisfies FC<Props>

frontend/src/components/common/TagInput.tsx

@@ -0,0 +1,97 @@
+import { useState } from 'react'
+
+import TagSearchBox from '@/components/TagSearchBox'
+import { apiGet } from '@/lib/api'
+
+import type { FC, ChangeEvent, KeyboardEvent } from 'react'
+
+import type { Tag } from '@/types'
+
+
+type Props = {
+    value:      string
+    setValue:   (value: string) => void }
+
+export default (({ value, setValue }: Props) => {
+  const [activeIndex, setActiveIndex] = useState (-1)
+  const [suggestions, setSuggestions] = useState<Tag[]> ([])
+  const [suggestionsVsbl, setSuggestionsVsbl] = useState (false)
+
+  // TODO: TagSearch からのコピペのため，共通化を考へる．
+  const whenChanged = async (ev: ChangeEvent<HTMLInputElement>) => {
+    setValue (ev.target.value)
+
+    const q = ev.target.value.trim ().split (' ').at (-1)
+    if (!(q))
+      {
+	setSuggestions ([])
+	return
+      }
+
+    const data = await apiGet<Tag[]> ('/tags/autocomplete', { params: { q } })
+    setSuggestions (data.filter (t => t.postCount > 0))
+    if (suggestions.length > 0)
+      setSuggestionsVsbl (true)
+  }
+
+  // TODO: TagSearch からのコピペのため，共通化を考へる．
+  const handleTagSelect = (tag: Tag) => {
+    const parts = value?.split (' ')
+    parts[parts.length - 1] = tag.name
+    setValue (parts.join (' ') + ' ')
+    setSuggestions ([])
+    setActiveIndex (-1)
+  }
+
+  // TODO: TagSearch からのコピペのため，共通化を考へる．
+  const handleKeyDown = (ev: KeyboardEvent<HTMLInputElement>) => {
+    switch (ev.key)
+    {
+    case 'ArrowDown':
+      ev.preventDefault ()
+      setActiveIndex (i => Math.min (i + 1, suggestions.length - 1))
+      setSuggestionsVsbl (true)
+      break
+
+    case 'ArrowUp':
+      ev.preventDefault ()
+      setActiveIndex (i => Math.max (i - 1, -1))
+      setSuggestionsVsbl (true)
+      break
+
+    case 'Enter':
+      if (activeIndex < 0)
+	break
+      ev.preventDefault ()
+      const selected = suggestions[activeIndex]
+      selected && handleTagSelect (selected)
+      break
+
+    case 'Escape':
+      ev.preventDefault ()
+      setSuggestionsVsbl (false)
+      break
+    }
+    if (ev.key === 'Enter' && (!(suggestionsVsbl) || activeIndex < 0))
+      {
+	setSuggestionsVsbl (false)
+      }
+  }
+
+  return (
+      <div className="relative">
+	<input
+	    type="text"
+	    value={value}
+	    onChange={whenChanged}
+	    onFocus={() => setSuggestionsVsbl (true)}
+	    onBlur={() => setSuggestionsVsbl (false)}
+	    onKeyDown={handleKeyDown}
+	    className="w-full border p-2 rounded"/>
+	<TagSearchBox
+	    suggestions={
+		suggestionsVsbl && suggestions.length > 0 ? suggestions : [] as Tag[]}
+	    activeIndex={activeIndex}
+	    onSelect={handleTagSelect}/>
+      </div>)
+}) satisfies FC<Props>

frontend/src/components/layout/MainArea.tsx

@@ -1,3 +1,5 @@
+import { motion } from 'framer-motion'
+
 import { cn } from '@/lib/utils'
 
 import type { FC, ReactNode } from 'react'
@@ -8,6 +10,9 @@ type Props = {
 
 
 export default (({ children, className }: Props) => (
-    <main className={cn ('flex-1 overflow-y-auto p-4', className)}>
+    <motion.main
+	transition={{ layout: { duration: .2, ease: 'easeOut' } }}
+	className={cn ('flex-1 overflow-y-auto p-4', className)}
+	layout="position">
       {children}
-    </main>)) satisfies FC<Props>
+    </motion.main>)) satisfies FC<Props>

frontend/src/components/layout/SidebarComponent.tsx

@@ -1,9 +1,30 @@
-import React from 'react'
+import { motion } from 'framer-motion'
+import { Helmet } from 'react-helmet-async'
 
-type Props = { children: React.ReactNode }
+import type { FC, ReactNode } from 'react'
+
+type Props = { children: ReactNode }
 
 
-export default ({ children }: Props) => (
-    <div className="p-4 w-full md:w-64 md:h-full">
+export default (({ children }: Props) => (
+    <motion.div
+	layout="position"
+	transition={{ layout: { duration: .2, ease: 'easeOut' } }}
+	className="p-4 w-full md:w-64 md:h-full md:overflow-y-auto sidebar">
+      <Helmet>
+	<style>
+	  {`
+	      .sidebar
+	      {
+		direction: rtl;
+	      }
+
+	      .sidebar > *
+	      {
+		direction: ltr;
+	      }`}
+	</style>
+      </Helmet>
+
       {children}
-    </div>)
+    </motion.div>)) satisfies FC<Props>

frontend/src/components/users/InheritDialogue.tsx

@@ -1,5 +1,3 @@
-import axios from 'axios'
-import toCamel from 'camelcase-keys'
 import { useState } from 'react'
 
 import { Button } from '@/components/ui/button'
@@ -8,7 +6,7 @@ import { Dialog,
          DialogTitle } from '@/components/ui/dialog'
 import { Input } from '@/components/ui/input'
 import { toast } from '@/components/ui/use-toast'
-import { API_BASE_URL } from '@/config'
+import { apiPost } from '@/lib/api'
 
 import type { User } from '@/types'
 
@@ -26,12 +24,12 @@ export default ({ visible, onVisibleChange, setUser }: Props) => {
 
     try
     {
-      const res = await axios.post (`${ API_BASE_URL }/users/verify`, { code: inputCode })
-      const data = res.data as { valid: boolean; user: any }
+      const data = await apiPost<{ valid: boolean; user: User }> (
+	  '/users/verify', { code: inputCode })
       if (data.valid)
 	{
 	  localStorage.setItem ('user_code', inputCode)
-	  setUser (toCamel (data.user, { deep: true }))
+	  setUser (data.user)
 	  toast ({ title: '引継ぎ成功!' })
 	  onVisibleChange (false)
 	}

frontend/src/components/users/UserCodeDialogue.tsx

@@ -1,11 +1,9 @@
-import axios from 'axios'
-
 import { Button } from '@/components/ui/button'
 import { Dialog,
 	 DialogContent,
 	 DialogTitle } from '@/components/ui/dialog'
 import { toast } from '@/components/ui/use-toast'
-import { API_BASE_URL } from '@/config'
+import { apiPost } from '@/lib/api'
 
 import type { User } from '@/types'
 
@@ -23,10 +21,8 @@ export default ({ visible, onVisibleChange, user, setUser }: Props) => {
     if (!(confirm ('引継ぎコードを再発行しますか?\n再発行するとほかのブラウザからはログアウトされます．')))
       return
 
-    const res = await axios.post (`${ API_BASE_URL }/users/code/renew`, { }, { headers: {
-	'Content-Type':     'multipart/form-data',
-	'X-Transfer-Code':  localStorage.getItem ('user_code') || '' } })
-    const data = res.data as { code: string }
+    const data = await apiPost<{ code: string }> ('/users/code/renew', { },
+	{ headers: { 'Content-Type': 'multipart/form-data' } })
     if (data.code)
       {
 	localStorage.setItem ('user_code', data.code)

frontend/src/consts.ts

@@ -3,13 +3,33 @@ import type { Category } from 'types'
 export const LIGHT_COLOUR_SHADE = 800
 export const DARK_COLOUR_SHADE = 300
 
-export const CATEGORIES = ['deerjikist',
+export const CATEGORIES = [
+    'deerjikist',
     'meme',
     'character',
     'general',
     'material',
     'meta',
-			   'nico'] as const
+    'nico',
+    ] as const
+
+export const CATEGORY_NAMES: Record<Category, string> = {
+    deerjikist: 'ニジラー',
+    meme:       '原作・ネタ元・ミーム等',
+    character:  'キャラクター',
+    general:    '一般',
+    material:   '素材',
+    meta:       'メタタグ',
+    nico:       'ニコニコタグ',
+    } as const
+
+export const FETCH_POSTS_ORDER_FIELDS = [
+    'title',
+    'url',
+    'original_created_at',
+    'created_at',
+    'updated_at',
+    ] as const
 
 export const TAG_COLOUR = {
     deerjikist: 'rose',
@@ -18,10 +38,13 @@ export const TAG_COLOUR = {
     general:    'cyan',
     material:   'orange',
     meta:       'yellow',
-    nico:       'gray' } as const satisfies Record<Category, string>
+    nico:       'gray',
+    } as const satisfies Record<Category, string>
 
 export const USER_ROLES = ['admin', 'member', 'guest'] as const
 
-export const ViewFlagBehavior = { OnShowedDetail: 1,
+export const ViewFlagBehavior = {
+    OnShowedDetail: 1,
     OnClickedLink:  2,
-				  NotAuto:        3 } as const
+    NotAuto:        3,
+    } as const

frontend/src/index.css

@@ -46,10 +46,12 @@ a
 body
 {
   margin: 0;
-  display: flex;
-  place-items: center;
   min-width: 320px;
-  min-height: 100vh;
+}
+
+#root
+{
+  min-height: 100dvh;
 }
 
 h1

frontend/src/lib/api.ts

@@ -3,9 +3,12 @@ import toCamel from 'camelcase-keys'
 
 import { API_BASE_URL } from '@/config'
 
+import type { AxiosError, AxiosRequestConfig } from 'axios'
+
 type Opt = {
-    params?:  Record<string, unknown>
-    headers?: Record<string, string> }
+    params?:        AxiosRequestConfig['params']
+    headers?:       Record<string, string>
+    responseType?:  'blob' }
 
 const client = axios.create ({ baseURL: API_BASE_URL })
 
@@ -23,6 +26,8 @@ const apiP = async <T> (
     opt?:   Opt,
 ): Promise<T> => {
   const res = await client[method] (path, body ?? { }, withUserCode (opt))
+  if (opt?.responseType === 'blob')
+    return res.data as T
   return toCamel (res.data as any, { deep: true }) as T
 }
 
@@ -32,6 +37,8 @@ export const apiGet = async <T> (
     opt?: Opt,
 ): Promise<T> => {
   const res = await client.get (path, withUserCode (opt))
+  if (opt?.responseType === 'blob')
+    return res.data as T
   return toCamel (res.data as any, { deep: true }) as T
 }
 
@@ -63,3 +70,6 @@ export const apiDelete = async (
 ): Promise<void> => {
   await client.delete (path, withUserCode (opt))
 }
+
+
+export const isApiError = (err: unknown): err is AxiosError => axios.isAxiosError (err)

frontend/src/lib/posts.ts

@@ -1,30 +1,47 @@
 import { apiDelete, apiGet, apiPost } from '@/lib/api'
 
-import type { Post } from '@/types'
+import type { FetchPostsParams, Post, PostVersion } from '@/types'
 
 
 export const fetchPosts = async (
-    { tags, match, page, limit, cursor }: {
-	tags:     string
-	match:    'any' | 'all'
-	page?:    number
-	limit?:   number
-	cursor?:  string }
+    { url, title, tags, match, createdFrom, createdTo, updatedFrom, updatedTo,
+      originalCreatedFrom, originalCreatedTo, page, limit, order }: FetchPostsParams,
 ): Promise<{
     posts:  Post[]
-    count:      number
-    nextCursor: string }> => await apiGet ('/posts', {
-	params: {
-	    tags,
-	    match,
+    count:  number }> =>
+	await apiGet ('/posts', { params: {
+	    ...(url && { url }),
+	    ...(title && { title }),
+	    ...(tags && { tags }),
+	    ...(match && { match }),
+	    ...(createdFrom && { created_from: createdFrom }),
+	    ...(createdTo && { created_to: createdTo }),
+	    ...(updatedFrom && { updated_from: updatedFrom }),
+	    ...(updatedTo && { updated_to: updatedTo }),
+	    ...(originalCreatedFrom && { original_created_from: originalCreatedFrom }),
+	    ...(originalCreatedTo && { original_created_to: originalCreatedTo }),
 	    ...(page && { page }),
 	    ...(limit && { limit }),
-	    ...(cursor && { cursor }) } })
+	    ...(order && { order }) } })
 
 
 export const fetchPost = async (id: string): Promise<Post> => await apiGet (`/posts/${ id }`)
 
 
+export const fetchPostChanges = async (
+    { post, tag, page, limit }: {
+	post?:  string
+	tag?:   string
+	page:   number
+	limit:  number },
+): Promise<{
+    versions: PostVersion[]
+    count:    number }> =>
+	await apiGet ('/posts/versions', { params: { ...(post && { post }),
+						     ...(tag && { tag }),
+						     page, limit } })
+
+
 export const toggleViewedFlg = async (id: string, viewed: boolean): Promise<void> => {
   await (viewed ? apiPost : apiDelete) (`/posts/${ id }/viewed`)
 }

frontend/src/lib/prefetchers.ts

@@ -1,22 +1,109 @@
 import { QueryClient } from '@tanstack/react-query'
 import { match } from 'path-to-regexp'
 
-import { fetchPost, fetchPosts } from '@/lib/posts'
-import { postsKeys } from '@/lib/queryKeys'
+import { fetchPost, fetchPosts, fetchPostChanges } from '@/lib/posts'
+import { postsKeys, tagsKeys, wikiKeys } from '@/lib/queryKeys'
+import { fetchTagByName, fetchTag, fetchTags } from '@/lib/tags'
+import { fetchWikiPage,
+	 fetchWikiPageByTitle,
+	 fetchWikiPages } from '@/lib/wiki'
+
+import type { Category, FetchPostsOrder, FetchTagsOrder } from '@/types'
 
 type Prefetcher = (qc: QueryClient, url: URL) => Promise<void>
 
 const mPost = match<{ id: string }> ('/posts/:id')
+const mWiki = match<{ title: string }> ('/wiki/:title')
+
+
+const prefetchWikiPagesIndex: Prefetcher = async (qc, url) => {
+  const title = url.searchParams.get ('title') ?? ''
+
+  await qc.prefetchQuery ({
+      queryKey: wikiKeys.index ({ title }),
+      queryFn:  () => fetchWikiPages ({ title }) })
+}
+
+
+const prefetchWikiPageShow: Prefetcher = async (qc, url) => {
+  const m = mWiki (url.pathname)
+  if (!(m))
+    return
+
+  const title = decodeURIComponent (m.params.title)
+  const version = url.searchParams.get ('version') || undefined
+
+  const wikiPage = await qc.fetchQuery ({
+      queryKey: wikiKeys.show (title, { version }),
+      queryFn:  () => fetchWikiPageByTitle (title, { version }) })
+
+  if (wikiPage)
+    {
+      const effectiveId = String (wikiPage.id ?? '')
+      await qc.prefetchQuery ({
+	  queryKey: wikiKeys.show (effectiveId, { }),
+	  queryFn: () => fetchWikiPage (effectiveId, { } ) })
+
+      if (wikiPage.body)
+	{
+	  await qc.prefetchQuery ({
+	      queryKey: wikiKeys.index ({ }),
+	      queryFn: () => fetchWikiPages ({ }) })
+	}
+    }
+
+  const effectiveTitle = wikiPage?.title ?? title
+
+  await qc.prefetchQuery ({
+      queryKey: tagsKeys.show (effectiveTitle),
+      queryFn: () => fetchTagByName (effectiveTitle) })
+
+  if (version)
+    return
+
+  const p = {
+      tags: effectiveTitle,
+      match: 'all',
+      page: 1,
+      limit: 8,
+      url: '',
+      title: '',
+      originalCreatedFrom: '',
+      originalCreatedTo: '',
+      createdFrom: '',
+      createdTo: '',
+      updatedFrom: '',
+      updatedTo: '',
+      order: 'original_created_at:desc' } as const
+  await qc.prefetchQuery ({
+      queryKey: postsKeys.index (p),
+      queryFn:  () => fetchPosts (p) })
+}
 
 
 const prefetchPostsIndex: Prefetcher = async (qc, url) => {
   const tags = url.searchParams.get ('tags') ?? ''
-  const m = url.searchParams.get ('match') === 'any' ? 'any' : 'all'
+  const qURL = url.searchParams.get ('url') ?? ''
+  const title = url.searchParams.get ('title') ?? ''
+  const originalCreatedFrom = url.searchParams.get ('original_created_from') ?? ''
+  const originalCreatedTo = url.searchParams.get ('original_created_to') ?? ''
+  const createdFrom = url.searchParams.get ('created_from') ?? ''
+  const createdTo = url.searchParams.get ('created_to') ?? ''
+  const updatedFrom = url.searchParams.get ('updated_from') ?? ''
+  const updatedTo = url.searchParams.get ('updated_to') ?? ''
+  const m: 'all' | 'any' = url.searchParams.get ('match') === 'any' ? 'any' : 'all'
   const page = Number (url.searchParams.get ('page') || 1)
   const limit = Number (url.searchParams.get ('limit') || 20)
+  const order = (url.searchParams.get ('order') ?? 'original_created_at:desc') as FetchPostsOrder
+
+  const keys = {
+      tags, match: m, page, limit, url: qURL, title,
+      originalCreatedFrom, originalCreatedTo, createdFrom, createdTo,
+      updatedFrom, updatedTo, order }
+
   await qc.prefetchQuery ({
-      queryKey: postsKeys.index ({ tags, match: m, page, limit }),
-      queryFn:  () => fetchPosts ({ tags, match: m, page, limit }) })
+      queryKey: postsKeys.index (keys),
+      queryFn:  () => fetchPosts (keys) })
 }
 
 
@@ -26,24 +113,81 @@ const prefetchPostShow: Prefetcher = async (qc, url) => {
     return
 
   const { id } = m.params
+
   await qc.prefetchQuery ({
       queryKey: postsKeys.show (id),
       queryFn:  () => fetchPost (id) })
 }
 
 
-export const routePrefetchers: {
-    test: (u: URL) => boolean
-    run:  Prefetcher }[] = [
-    { test: u => u.pathname === '/' || u.pathname === '/posts', run: prefetchPostsIndex },
-    { test: u => Boolean (mPost (u.pathname)), run: prefetchPostShow }]
+const prefetchPostChanges: Prefetcher = async (qc, url) => {
+  const id = url.searchParams.get ('id')
+  const tag = url.searchParams.get ('tag')
+  const page = Number (url.searchParams.get ('page') || 1)
+  const limit = Number (url.searchParams.get ('limit') || 20)
+
+  if (tag)
+    {
+      await qc.prefetchQuery ({
+	  queryKey: tagsKeys.show (tag),
+	  queryFn: () => fetchTag (tag) })
+    }
+
+  await qc.prefetchQuery ({
+      queryKey: postsKeys.changes ({ ...(id && { id }),
+				     ...(tag && { tag }),
+				     page, limit }),
+      queryFn:  () => fetchPostChanges ({ ...(id && { id }),
+					  ...(tag && { tag }),
+					  page, limit }) })
+}
+
+
+const prefetchTagsIndex: Prefetcher = async (qc, url) => {
+  const postRaw = url.searchParams.get ('post')
+  const post = postRaw ? Number (postRaw) : null
+  const name = url.searchParams.get ('name') ?? ''
+  const category = (url.searchParams.get ('category') || null) as Category | null
+  const postCountGTE = Number (url.searchParams.get ('post_count_gte') || 1)
+  const postCountLTERaw = url.searchParams.get ('post_count_lte')
+  const postCountLTE = postCountLTERaw ? Number (postCountLTERaw) : null
+  const createdFrom = url.searchParams.get ('created_from') ?? ''
+  const createdTo = url.searchParams.get ('created_to') ?? ''
+  const updatedFrom = url.searchParams.get ('updated_from') ?? ''
+  const updatedTo = url.searchParams.get ('updated_to') ?? ''
+  const page = Number (url.searchParams.get ('page') || 1)
+  const limit = Number (url.searchParams.get ('limit') || 20)
+  const order = (url.searchParams.get ('order') ?? 'post_count:desc') as FetchTagsOrder
+
+  const keys = {
+      post, name, category, postCountGTE, postCountLTE, createdFrom, createdTo,
+      updatedFrom, updatedTo, page, limit, order }
+
+  await qc.prefetchQuery ({
+      queryKey: tagsKeys.index (keys),
+      queryFn:  () => fetchTags (keys) })
+}
+
+
+export const routePrefetchers: { test: (u: URL) => boolean; run: Prefetcher }[] = [
+    { test: u => ['/', '/posts', '/posts/search'].includes (u.pathname),
+      run: prefetchPostsIndex },
+    { test: u => (!(['/posts/new', '/posts/changes', '/posts/search'].includes (u.pathname))
+		  && Boolean (mPost (u.pathname))),
+      run: prefetchPostShow },
+    { test: u => u.pathname === '/posts/changes', run: prefetchPostChanges },
+    { test: u => u.pathname === '/wiki', run: prefetchWikiPagesIndex },
+    { test: u => (!(['/wiki/new', '/wiki/changes'].includes (u.pathname))
+		  && Boolean (mWiki (u.pathname))),
+      run: prefetchWikiPageShow },
+    { test: u => u.pathname === '/tags', run: prefetchTagsIndex }]
 
 
 export const prefetchForURL = async (qc: QueryClient, urlLike: string): Promise<void> => {
   const u = new URL (urlLike, location.origin)
-  const jobs = routePrefetchers.filter (r => r.test (u)).map (r => r.run (qc, u))
-  if (jobs.length === 0)
+  const r = routePrefetchers.find (x => x.test (u))
+  if (!(r))
     return
 
-  await Promise.all (jobs)
+  await r.run (qc, u)
 }

frontend/src/lib/queryKeys.ts

@@ -1,10 +1,19 @@
+import type { FetchPostsParams, FetchTagsParams } from '@/types'
+
 export const postsKeys = {
     root:     ['posts'] as const,
-    index:    (p: { tags: string; match: 'any' | 'all'; page: number; limit: number }) =>
-		  ['posts', 'index', p] as const,
+    index:    (p: FetchPostsParams) => ['posts', 'index', p] as const,
     show:     (id: string) => ['posts', id] as const,
-    related:  (id: string) => ['related', id] as const }
+    related:  (id: string) => ['related', id] as const,
+    changes:  (p: { post?: string; tag?: string; page: number; limit: number }) =>
+		  ['posts', 'changes', p] as const }
+
+export const tagsKeys = {
+    root:   ['tags'] as const,
+    index:  (p: FetchTagsParams) => ['tags', 'index', p] as const,
+    show:   (name: string) => ['tags', name] as const }
 
 export const wikiKeys = {
     root:   ['wiki'] as const,
-    show: (title: string, p: { version: string }) => ['wiki', title, p] as const }
+    index:  (p: { title?: string }) => ['wiki', 'index', p] as const,
+    show:   (title: string, p: { version?: string }) => ['wiki', title, p] as const }