Merge branch 'main' into feature/184

backend/Gemfile

@@ -46,6 +46,8 @@ group :development, :test do
 
   # Omakase Ruby styling [https://github.com/rails/rubocop-rails-omakase/]
   gem "rubocop-rails-omakase", require: false
+
+  gem 'factory_bot_rails'
 end
 
 

backend/Gemfile.lock

@@ -99,6 +99,11 @@ GEM
     drb (2.2.1)
     ed25519 (1.4.0)
     erubi (1.13.1)
+    factory_bot (6.5.6)
+      activesupport (>= 6.1.0)
+    factory_bot_rails (6.5.1)
+      factory_bot (~> 6.5)
+      railties (>= 6.1.0)
     ffi (1.17.2-aarch64-linux-gnu)
     ffi (1.17.2-aarch64-linux-musl)
     ffi (1.17.2-arm-linux-gnu)
@@ -441,6 +446,7 @@ DEPENDENCIES
   diff-lcs
   discard
   dotenv-rails
+  factory_bot_rails
   gollum
   image_processing (~> 1.14)
   jwt

backend/app/controllers/nico_tags_controller.rb

@@ -1,9 +1,13 @@
 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(:linked_tags).order(updated_at: :desc)
+    q = Tag.nico_tags
+           .includes(:tag_name, linked_tags: :tag_name)
+           .order(updated_at: :desc)
     q = q.where('tags.updated_at < ?', Time.iso8601(cursor)) if cursor
 
     tags = q.limit(limit + 1)
@@ -15,7 +19,9 @@ class NicoTagsController < ApplicationController
     end
 
     render json: { tags: tags.map { |tag|
-      tag.as_json(include: :linked_tags)
+      tag.as_json(TAG_JSON).merge(linked_tags: tag.linked_tags.map { |lt|
+        lt.as_json(TAG_JSON)
+      })
     }, next_cursor: }
   end
 
@@ -30,12 +36,11 @@ class NicoTagsController < ApplicationController
 
     linked_tag_names = params[:tags].to_s.split(' ')
     linked_tags = Tag.normalise_tags(linked_tag_names, with_tagme: false)
-    return head :bad_request if linked_tags.filter { |t| t.category == 'nico' }.present?
+    return head :bad_request if linked_tags.any? { |t| t.category == 'nico' }
 
     tag.linked_tags = linked_tags
-    tag.updated_at = Time.now
     tag.save!
 
-    render json: tag.linked_tags, status: :ok
+    render json: tag.linked_tags.map { |t| t.as_json(TAG_JSON) }, status: :ok
   end
 end

backend/app/controllers/posts_controller.rb

@@ -1,7 +1,6 @@
 class PostsController < ApplicationController
   Event = Struct.new(:post, :tag, :user, :change_type, :timestamp, keyword_init: true)
 
-  # GET /posts
   def index
     page = (params[:page].presence || 1).to_i
     limit = (params[:limit].presence || 20).to_i
@@ -18,7 +17,7 @@ class PostsController < ApplicationController
         'posts.created_at)'
     q =
         filtered_posts
-        .preload(:tags)
+        .preload(tags: :tag_name)
         .with_attached_thumbnail
         .select("posts.*, #{ sort_sql } AS sort_ts")
         .order(Arel.sql("#{ sort_sql } DESC"))
@@ -36,7 +35,8 @@ class PostsController < ApplicationController
     end
 
     render json: { posts: posts.map { |post|
-      post.as_json(include: { tags: { only: [:id, :name, :category, :post_count] } }).tap do |json|
+      post.as_json(include: { tags: { only: [:id, :category, :post_count],
+                                      methods: [:name] } }).tap do |json|
         json['thumbnail'] =
             if post.thumbnail.attached?
               rails_storage_proxy_url(post.thumbnail, only_path: false)
@@ -48,19 +48,19 @@ class PostsController < ApplicationController
   end
 
   def random
-    post = filtered_posts.order('RAND()').first
+    post = filtered_posts.preload(tags: :tag_name).order('RAND()').first
     return head :not_found unless post
 
     viewed = current_user&.viewed?(post) || false
 
     render json: (post
-                  .as_json(include: { tags: { only: [:id, :name, :category, :post_count] } })
+                  .as_json(include: { tags: { only: [:id, :category, :post_count],
+                                              methods: [:name] } })
                   .merge(viewed:))
   end
 
-  # GET /posts/1
   def show
-    post = Post.includes(:tags).find(params[:id])
+    post = Post.includes(tags: :tag_name).find(params[:id])
     return head :not_found unless post
 
     viewed = current_user&.viewed?(post) || false
@@ -73,7 +73,6 @@ class PostsController < ApplicationController
     render json:
   end
 
-  # POST /posts
   def create
     return head :unauthorized unless current_user
     return head :forbidden unless current_user.member?
@@ -96,7 +95,8 @@ class PostsController < ApplicationController
       tags = Tag.normalise_tags(tag_names)
       tags = Tag.expand_parent_tags(tags)
       sync_post_tags!(post, tags)
-      render json: post.as_json(include: { tags: { only: [:id, :name, :category, :post_count] } }),
+      render json: post.as_json(include: { tags: { only: [:id, :category, :post_count],
+                                                   methods: [:name] } }),
              status: :created
     else
       render json: { errors: post.errors.full_messages }, status: :unprocessable_entity
@@ -117,7 +117,6 @@ class PostsController < ApplicationController
     head :no_content
   end
 
-  # PATCH/PUT /posts/1
   def update
     return head :unauthorized unless current_user
     return head :forbidden unless current_user.member?
@@ -153,13 +152,13 @@ class PostsController < ApplicationController
 
     pts = PostTag.with_discarded
     pts = pts.where(post_id: id) if id.present?
-    pts = pts.includes(:post, :tag, :created_user, :deleted_user)
+    pts = pts.includes(:post, { tag: :tag_name }, :created_user, :deleted_user)
 
     events = []
     pts.each do |pt|
       events << Event.new(
           post:         pt.post,
-          tag:          pt.tag,
+          tag:          pt.tag.as_json(only: [:id, :category], methods: [:name]),
           user:         pt.created_user && { id: pt.created_user.id, name: pt.created_user.name },
           change_type:  'add',
           timestamp:    pt.created_at)
@@ -167,7 +166,7 @@ class PostsController < ApplicationController
       if pt.discarded_at
         events << Event.new(
             post:         pt.post,
-            tag:          pt.tag,
+            tag:          pt.tag.as_json(only: [:id, :category], methods: [:name]),
             user:         pt.deleted_user && { id: pt.deleted_user.id, name: pt.deleted_user.name },
             change_type:  'remove',
             timestamp:    pt.discarded_at)
@@ -192,15 +191,15 @@ class PostsController < ApplicationController
   end
 
   def filter_posts_by_tags tag_names, match_type
-    posts = Post.joins(:tags)
+    posts = Post.joins(tags: :tag_name)
+
     if match_type == 'any'
-      posts = posts.where(tags: { name: tag_names }).distinct
+      posts.where(tag_names: { name: tag_names }).distinct
     else
-      tag_names.each do |tag|
-        posts = posts.where(id: Post.joins(:tags).where(tags: { name: tag }))
-      end
+      posts.where(tag_names: { name: tag_names })
+           .group('posts.id')
+           .having('COUNT(DISTINCT tag_names.id) = ?', tag_names.uniq.size)
     end
-    posts.distinct
   end
 
   def sync_post_tags! post, desired_tags
@@ -251,7 +250,8 @@ class PostsController < ApplicationController
       return nil unless tag
 
       if path.include?(tag_id)
-        return tag.as_json(only: [:id, :name, :category, :post_count]).merge(children: [])
+        return tag.as_json(only: [:id, :category, :post_count],
+                           methods: [:name]).merge(children: [])
       end
 
       if memo.key?(tag_id)
@@ -263,7 +263,8 @@ class PostsController < ApplicationController
 
       children = child_ids.filter_map { |cid| build_node.(cid, new_path) }
 
-      memo[tag_id] = tag.as_json(only: [:id, :name, :category, :post_count]).merge(children:)
+      memo[tag_id] = tag.as_json(only: [:id, :category, :post_count],
+                                 methods: [:name]).merge(children:)
     end
 
     root_ids.filter_map { |id| build_node.call(id, []) }

backend/app/controllers/tags_controller.rb

@@ -1,35 +1,45 @@
 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
-           end
-    render json: tags
+
+    tags =
+        if post_id.present?
+          Tag.joins(:posts).where(posts: { id: post_id })
+        else
+          Tag.all
+        end
+
+    render json: tags.as_json(only: [:id, :category, :post_count], methods: [:name, :has_wiki])
   end
 
   def autocomplete
     q = params[:q].to_s.strip
     return render json: [] if q.blank?
 
-    tags = (Tag
-            .where('(category = ? AND name LIKE ?) OR name LIKE ?',
+    tags = (Tag.joins(:tag_name).includes(:tag_name)
+            .where('(tags.category = ? AND tag_names.name LIKE ?) OR tag_names.name LIKE ?',
                    'nico', "nico:#{ q }%", "#{ q }%")
-            .order('post_count DESC, name ASC')
+            .order(Arel.sql('post_count DESC, tag_names.name ASC'))
             .limit(20))
-    render json: tags
+    render json: tags.as_json(only: [:id, :category, :post_count], methods: [:name, :has_wiki])
   end
 
   def show
-    tag = Tag.find(params[:id])
-    render json: tag
+    tag = Tag.find_by(id: params[:id])
+    if tag
+      render json: tag.as_json(only: [:id, :category, :post_count], methods: [:name, :has_wiki])
+    else
+      head :not_found
+    end
   end
 
   def show_by_name
-    tag = Tag.find_by(name: params[:name])
+    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: })
     if tag
-      render json: tag
+      render json: tag.as_json(only: [:id, :category, :post_count], methods: [:name, :has_wiki])
     else
       head :not_found
     end

backend/app/controllers/users_controller.rb

@@ -18,6 +18,8 @@ class UsersController < ApplicationController
   end
 
   def renew
+    return head :unauthorized unless current_user
+
     user = current_user
     user.inheritance_code = SecureRandom.uuid
     user.save!

backend/app/controllers/wiki_pages_controller.rb

@@ -2,19 +2,25 @@ class WikiPagesController < ApplicationController
   rescue_from Wiki::Commit::Conflict, with: :render_wiki_conflict
 
   def index
-    render json: WikiPage.all
+    pages = WikiPage.all
+    render json: pages.as_json(methods: [:title])
   end
 
   def show
-    render_wiki_page_or_404 WikiPage.find(params[:id])
+    page = WikiPage.find_by(id: params[:id])
+    render_wiki_page_or_404 page
   end
 
   def show_by_title
-    render_wiki_page_or_404 WikiPage.find_by(title: params[:title])
+    title = params[:title].to_s.strip
+    page = WikiPage.joins(:tag_name)
+                   .includes(:tag_name)
+                   .find_by(tag_names: { name: title })
+    render_wiki_page_or_404 page
   end
 
   def exists
-    if WikiPage.exists?(params[:id])
+    if WikiPage.exists?(id: params[:id])
       head :no_content
     else
       head :not_found
@@ -22,7 +28,8 @@ class WikiPagesController < ApplicationController
   end
 
   def exists_by_title
-    if WikiPage.exists?(title: params[:title])
+    title = params[:title].to_s.strip
+    if WikiPage.joins(:tag_name).exists?(tag_names: { name: title })
       head :no_content
     else
       head :not_found
@@ -81,7 +88,7 @@ class WikiPagesController < ApplicationController
       message = params[:message].presence
       Wiki::Commit.content!(page:, body:, created_user: current_user, message:)
 
-      render json: page, status: :created
+      render json: page.as_json(methods: [:title]), status: :created
     else
       render json: { errors: page.errors.full_messages },
              status: :unprocessable_entity
@@ -115,14 +122,14 @@ class WikiPagesController < ApplicationController
   end
 
   def search
-    title = params[:title]&.strip
+    title = params[:title].to_s.strip
 
-    q = WikiPage.all
+    q = WikiPage.joins(:tag_name).includes(:tag_name)
     if title.present?
-      q = q.where('title LIKE ?', "%#{ WikiPage.sanitize_sql_like(title) }%")
+      q = q.where('tag_names.name LIKE ?', "%#{ WikiPage.sanitize_sql_like(title) }%")
     end
 
-    render json: q.limit(20)
+    render json: q.limit(20).as_json(methods: [:title])
   end
 
   def changes
@@ -162,12 +169,14 @@ class WikiPagesController < ApplicationController
       pred = page.pred_revision_id(revision_id)
       succ = page.succ_revision_id(revision_id)
 
-      return render json: page.as_json.merge(body:, revision_id:, pred:, succ:)
+      return render json: page.as_json(methods: [:title])
+                              .merge(body:, revision_id:, pred:, succ:)
     end
 
     rev = page.current_revision
     unless rev
-      return render json: page.as_json.merge(body: nil, revision_id: nil, pred: nil, succ: nil)
+      return render json: page.as_json(methods: [:title])
+                              .merge(body: nil, revision_id: nil, pred: nil, succ: nil)
     end
 
     if rev.redirect?
@@ -181,7 +190,7 @@ class WikiPagesController < ApplicationController
     pred = page.pred_revision_id(revision_id)
     succ = page.succ_revision_id(revision_id)
 
-    render json: page.as_json.merge(body:, revision_id:, pred:, succ:)
+    render json: page.as_json(methods: [:title]).merge(body:, revision_id:, pred:, succ:)
   end
 
   def render_wiki_conflict err

backend/app/models/post_tag.rb

@@ -1,6 +1,10 @@
 class PostTag < ApplicationRecord
   include Discard::Model
 
+  before_destroy do
+    raise ActiveRecord::ReadOnlyRecord, '消さないでください．'
+  end
+
   belongs_to :post
   belongs_to :tag, counter_cache: :post_count
   belongs_to :created_user, class_name: 'User', optional: true

backend/app/models/tag.rb

@@ -21,6 +21,10 @@ class Tag < ApplicationRecord
                                        dependent: :destroy
   has_many :parents, through: :reversed_tag_implications, source: :parent_tag
 
+  belongs_to :tag_name
+  delegate :name, to: :tag_name, allow_nil: true
+  validates :tag_name, presence: true
+
   enum :category, { deerjikist:  'deerjikist',
                     meme:        'meme',
                     character:   'character',
@@ -29,7 +33,6 @@ class Tag < ApplicationRecord
                     nico:        'nico',
                     meta:        'meta' }
 
-  validates :name, presence: true, length: { maximum: 255 }
   validates :category, presence: true, inclusion: { in: Tag.categories.keys }
 
   validate :nico_tag_name_must_start_with_nico
@@ -44,31 +47,35 @@ class Tag < ApplicationRecord
       'mtr:'  => 'material',
       'meta:' => 'meta' }.freeze
 
+  def name= val
+    (self.tag_name ||= build_tag_name).name = val
+  end
+
+  def has_wiki
+    tag_name&.wiki_page.present?
+  end
+
   def self.tagme
-    @tagme ||= Tag.find_or_create_by!(name: 'タグ希望') do |tag|
-      tag.category = 'meta'
-    end
+    @tagme ||= find_or_create_by_tag_name!('タグ希望', category: 'meta')
   end
 
   def self.bot
-    @bot ||= Tag.find_or_create_by!(name: 'bot操作') do |tag|
-      tag.category = 'meta'
-    end
+    @bot ||= find_or_create_by_tag_name!('bot操作', category: 'meta')
   end
 
   def self.normalise_tags tag_names, with_tagme: true
     tags = tag_names.map do |name|
       pf, cat = CATEGORY_PREFIXES.find { |p, _| name.start_with?(p) } || ['', nil]
       name.delete_prefix!(pf)
-      Tag.find_or_initialize_by(name:).tap do |tag|
+      find_or_create_by_tag_name!(name, category: (cat || 'general')).tap do |tag|
         if cat && tag.category != cat
-          tag.category = cat
-          tag.save!
+          tag.update!(category: cat)
         end
       end
     end
+
     tags << Tag.tagme if with_tagme && tags.size < 10 && tags.none?(Tag.tagme)
-    tags.uniq
+    tags.uniq(&:id)
   end
 
   def self.expand_parent_tags tags
@@ -94,11 +101,19 @@ class Tag < ApplicationRecord
     (result + tags).uniq { |t| t.id }
   end
 
+  def self.find_or_create_by_tag_name!(name, category:)
+    tn = TagName.find_or_create_by!(name: name.to_s.strip)
+    Tag.find_or_create_by!(tag_name_id: tn.id) do |t|
+      t.category = category
+    end
+  end
+
   private
 
   def nico_tag_name_must_start_with_nico
-    if ((category == 'nico' && !(name.start_with?('nico:'))) || 
-        (category != 'nico' && name.start_with?('nico:')))
+    n = name.to_s
+    if ((category == 'nico' && !(n.start_with?('nico:'))) || 
+        (category != 'nico' && n.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

backend/app/models/tag_name.rb

@@ -0,0 +1,9 @@
+class TagName < ApplicationRecord
+  has_one :tag
+  has_one :wiki_page
+
+  belongs_to :canonical, class_name: 'TagName', optional: true
+  has_many :aliases, class_name: 'TagName', foreign_key: :canonical_id
+
+  validates :name, presence: true, length: { maximum: 255 }, uniqueness: true
+end

backend/app/models/wiki_page.rb

@@ -11,7 +11,16 @@ class WikiPage < ApplicationRecord
            foreign_key: :redirect_page_id,
            dependent: :nullify
 
-  validates :title, presence: true, length: { maximum: 255 }, uniqueness: true
+  belongs_to :tag_name
+  validates :tag_name, presence: true
+
+  def title
+    tag_name.name
+  end
+
+  def title= val
+    (self.tag_name ||= build_tag_name).name = val
+  end
 
   def current_revision
     wiki_revisions.order(id: :desc).first

backend/config/application.rb

@@ -11,6 +11,9 @@ module Backend
     # Initialize configuration defaults for originally generated Rails version.
     config.load_defaults 8.0
 
+    config.i18n.available_locales = [:ja, :en]
+    config.i18n.default_locale = :ja
+
     # Please, add to the `ignore` list any other `lib` subdirectories that do
     # not contain `.rb` files, or that should not be reloaded or eager loaded.
     # Common ones are `templates`, `generators`, or `middleware`, for example.

backend/config/locales/ja.yml

@@ -0,0 +1,2 @@
+ja:
+  hello: 'ぬ゛〜゛ん゛'

backend/db/migrate/20260111180600_create_tag_names.rb

@@ -0,0 +1,10 @@
+class CreateTagNames < ActiveRecord::Migration[7.0]
+  def change
+    create_table :tag_names do |t|
+      t.string :name, limit: 255, null: false
+      t.references :canonical, null: true, foreign_key: { to_table: :tag_names }, index: true
+      t.timestamps
+    end
+    add_index :tag_names, :name, unique: true
+  end
+end

backend/db/migrate/20260111192600_add_tag_name_to_tags.rb

@@ -0,0 +1,42 @@
+class AddTagNameToTags < ActiveRecord::Migration[7.0]
+  class Tag < ApplicationRecord
+    self.table_name = 'tags'
+  end
+
+  class TagName < ApplicationRecord
+    self.table_name = 'tag_names'
+  end
+
+  def up
+    add_reference :tags, :tag_name, null: true, foreign_key: true, index: false, after: :id
+    add_index :tags, :tag_name_id, unique: true
+
+    Tag.find_each do |tag|
+      name = tag.read_attribute(:name)
+      tn = TagName.find_or_create_by!(name:) do |r|
+        r.canonical_id = nil
+      end
+      tag.update_columns(tag_name_id: tn.id)
+    end
+
+    change_column_null :tags, :tag_name_id, false
+
+    remove_column :tags, :name
+  end
+
+  def down
+    add_column :tags, :name, :string, limit: 255, null: true, after: :id
+
+    Tag.find_each do |tag|
+      tag_name_id = tag.read_attribute(:tag_name_id)
+      name = TagName.find(tag_name_id).read_attribute(:name)
+      tag.update_columns(name:)
+    end
+
+    change_column_null :tags, :name, false
+
+    remove_foreign_key :tags, column: :tag_name_id
+    remove_index :tags, :tag_name_id
+    remove_column :tags, :tag_name_id
+  end
+end

backend/db/migrate/20260111204400_add_tag_name_to_wiki_pages.rb

@@ -0,0 +1,42 @@
+class AddTagNameToWikiPages < ActiveRecord::Migration[7.0]
+  class WikiPage < ApplicationRecord
+    self.table_name = 'wiki_pages'
+  end
+
+  class TagName < ApplicationRecord
+    self.table_name = 'tag_names'
+  end
+
+  def up
+    add_reference :wiki_pages, :tag_name, null: true, foreign_key: true, index: false, after: :id
+    add_index :wiki_pages, :tag_name_id, unique: true
+
+    WikiPage.find_each do |page|
+      name = page.read_attribute(:title)
+      tn = TagName.find_or_create_by!(name:) do |r|
+        r.canonical_id = nil
+      end
+      page.update_columns(tag_name_id: tn.id)
+    end
+
+    change_column_null :wiki_pages, :tag_name_id, false
+
+    remove_column :wiki_pages, :title
+  end
+
+  def down
+    add_column :wiki_pages, :title, :string, limit: 255, null: true, after: :id
+
+    WikiPage.find_each do |page|
+      tag_name_id = page.read_attribute(:tag_name_id)
+      title = TagName.find(tag_name_id).read_attribute(:name)
+      page.update_columns(title:)
+    end
+
+    change_column_null :wiki_pages, :title, false
+
+    remove_foreign_key :wiki_pages, column: :tag_name_id
+    remove_index :wiki_pages, :tag_name_id
+    remove_column :wiki_pages, :tag_name_id
+  end
+end

backend/db/migrate/20260112111800_drop_tag_aliases.rb

@@ -0,0 +1,9 @@
+class DropTagAliases < ActiveRecord::Migration[7.0]
+  def up
+    drop_table :tag_aliases
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration, '戻せません．'
+  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_07_034300) do
+ActiveRecord::Schema[8.0].define(version: 2026_01_12_111800) 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
@@ -106,14 +106,6 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_07_034300) do
     t.index ["user_id"], name: "index_settings_on_user_id"
   end
 
-  create_table "tag_aliases", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.bigint "tag_id", null: false
-    t.string "name", null: false
-    t.datetime "created_at", null: false
-    t.datetime "updated_at", null: false
-    t.index ["tag_id"], name: "index_tag_aliases_on_tag_id"
-  end
-
   create_table "tag_implications", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "tag_id", null: false
     t.bigint "parent_tag_id", null: false
@@ -124,6 +116,15 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_07_034300) do
     t.index ["tag_id"], name: "index_tag_implications_on_tag_id"
   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.index ["canonical_id"], name: "index_tag_names_on_canonical_id"
+    t.index ["name"], name: "index_tag_names_on_name", unique: true
+  end
+
   create_table "tag_similarities", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "tag_id", null: false
     t.bigint "target_tag_id", null: false
@@ -133,11 +134,12 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_07_034300) do
   end
 
   create_table "tags", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.string "name", null: false
+    t.bigint "tag_name_id", null: false
     t.string "category", default: "general", null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.integer "post_count", default: 0, null: false
+    t.index ["tag_name_id"], name: "index_tags_on_tag_name_id", unique: true
   end
 
   create_table "user_ips", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
@@ -176,12 +178,13 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_07_034300) do
   end
 
   create_table "wiki_pages", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.string "title", null: false
+    t.bigint "tag_name_id", null: false
     t.bigint "created_user_id", null: false
     t.bigint "updated_user_id", null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.index ["created_user_id"], name: "index_wiki_pages_on_created_user_id"
+    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
 
@@ -228,15 +231,17 @@ ActiveRecord::Schema[8.0].define(version: 2026_01_07_034300) do
   add_foreign_key "posts", "posts", column: "parent_id"
   add_foreign_key "posts", "users", column: "uploaded_user_id"
   add_foreign_key "settings", "users"
-  add_foreign_key "tag_aliases", "tags"
   add_foreign_key "tag_implications", "tags"
   add_foreign_key "tag_implications", "tags", column: "parent_tag_id"
+  add_foreign_key "tag_names", "tag_names", column: "canonical_id"
   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 "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_pages", "tag_names"
   add_foreign_key "wiki_pages", "users", column: "created_user_id"
   add_foreign_key "wiki_pages", "users", column: "updated_user_id"
   add_foreign_key "wiki_revision_lines", "wiki_lines"

backend/lib/tasks/sync_nico.rake

@@ -4,6 +4,7 @@ namespace :nico do
     require 'open3'
     require 'open-uri'
     require 'nokogiri'
+    require 'set'
 
     fetch_thumbnail = -> url do
       html = URI.open(url, read_timeout: 60, 'User-Agent' => 'Mozilla/5.0').read
@@ -12,9 +13,9 @@ namespace :nico do
       doc.at('meta[name="thumbnail"]')&.[]('content').presence
     end
 
-    def sync_post_tags! post, desired_tag_ids
+    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
-      current_ids = post.tags.pluck(:id).to_set
 
       to_add = desired_ids - current_ids
       to_remove = current_ids - desired_ids
@@ -43,12 +44,12 @@ namespace :nico do
 
     data = JSON.parse(stdout)
     data.each do |datum|
-      post = Post.where('url LIKE ?', '%nicovideo.jp%').find { |post|
-        post.url =~ %r{#{ Regexp.escape(datum['code']) }(?!\d)}
-      }
+      code = datum['code']
+      post = Post.where('url REGEXP ?', "nicovideo\\.jp/watch/#{ Regexp.escape(code) }([^0-9]|$)")
+                 .first
       unless post
         title = datum['title']
-        url = "https://www.nicovideo.jp/watch/#{ datum['code'] }"
+        url = "https://www.nicovideo.jp/watch/#{ code }"
         thumbnail_base = fetch_thumbnail.(url) rescue nil
         post = Post.new(title:, url:, thumbnail_base:, uploaded_user: nil)
         if thumbnail_base.present?
@@ -62,21 +63,19 @@ namespace :nico do
         sync_post_tags!(post, [Tag.tagme.id])
       end
 
-      kept_tags = post.tags.reload
-      kept_non_nico_ids = kept_tags.where.not(category: 'nico').pluck(:id).to_set
+      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
 
       desired_nico_ids = []
       desired_non_nico_ids = []
       datum['tags'].each do |raw|
         name = "nico:#{ raw }"
-        tag = Tag.find_or_initialize_by(name:) do |t|
-          t.category = 'nico'
-        end
-        tag.save! if tag.new_record?
+        tag = Tag.find_or_create_by_tag_name!(name, category: 'nico')
         desired_nico_ids << tag.id
-        unless tag.in?(kept_tags)
-          desired_non_nico_ids.concat(tag.linked_tags.pluck(:id))
-          desired_nico_ids.concat(tag.linked_tags.pluck(:id))
+        unless tag.id.in?(kept_ids)
+          linked_ids = tag.linked_tags.pluck(:id)
+          desired_non_nico_ids.concat(linked_ids)
+          desired_nico_ids.concat(linked_ids)
         end
       end
       desired_nico_ids.uniq!
@@ -89,7 +88,7 @@ namespace :nico do
       end
       desired_all_ids.uniq!
 
-      sync_post_tags!(post, desired_all_ids)
+      sync_post_tags!(post, desired_all_ids, current_ids: kept_ids)
     end
   end
 end

backend/spec/factories/tag_names.rb

@@ -0,0 +1,5 @@
+FactoryBot.define do
+  factory :tag_name do
+    name { "tag-#{SecureRandom.hex(4)}" }
+  end
+end

backend/spec/factories/tags.rb

@@ -0,0 +1,12 @@
+FactoryBot.define do
+  factory :tag do
+    category { 'general' }
+    post_count { 0 }
+    association :tag_name
+
+    trait :nico do
+      category { 'nico' }
+      tag_name { association(:tag_name, name: "nico:#{ SecureRandom.hex(4) }") }
+    end
+  end
+end

backend/spec/factories/users.rb

@@ -0,0 +1,11 @@
+FactoryBot.define do
+  factory :user do
+    name { "test-user" }
+    inheritance_code { SecureRandom.uuid }
+    role { "guest" }
+
+    trait :member do
+      role { "member" }
+    end
+  end
+end

backend/spec/factories/wiki_pages.rb

@@ -0,0 +1,7 @@
+FactoryBot.define do
+  factory :wiki_page do
+    title { "TestPage" }
+    association :created_user, factory: :user
+    association :updated_user, factory: :user
+  end
+end

backend/spec/rails_helper.rb

@@ -8,6 +8,10 @@ abort("The Rails environment is running in production mode!") if Rails.env.produ
 # that will avoid rails generators crashing because migrations haven't been run yet
 # return unless Rails.env.test?
 require 'rspec/rails'
+Dir[Rails.root.join('spec/support/**/*.rb')].each do |f|
+  require f
+end
+
 # Add additional requires below this line. Rails is not loaded until this point!
 
 # Requires supporting ruby files with custom matchers and macros, etc, in
@@ -34,11 +38,20 @@ begin
 rescue ActiveRecord::PendingMigrationError => e
   abort e.to_s.strip
 end
-Dir[Rails.root.join('spec/support/**/*.rb')].each do |f|
-  require f
-end
 RSpec.configure do |config|
+  config.before do
+    I18n.locale = :en
+  end
+
   config.include TestRecords
+  config.include RakeTaskHelper
+
+  # FactoryBot の create / create_list を使へるやぅにする
+  config.include FactoryBot::Syntax::Methods
+
+  # request spec で helper 使へるやぅにする
+  config.include AuthHelper, type: :request
+  config.include JsonHelper, type: :request
 
   # Remove this line if you're not using ActiveRecord or ActiveRecord fixtures
   config.fixture_paths = [

backend/spec/requests/nico_tags_spec.rb

@@ -0,0 +1,38 @@
+require 'rails_helper'
+
+
+RSpec.describe 'NicoTags', type: :request do
+  describe 'GET /tags/nico' do
+    it 'returns tags and next_cursor when overflowing limit' do
+      create_list(:tag, 21, :nico)
+      get '/tags/nico', params: { limit: 20 }
+      expect(response).to have_http_status(:ok)
+      expect(json['tags'].size).to eq(20)
+      expect(json['next_cursor']).to be_present
+    end
+  end
+
+  describe 'PATCH /tags/nico/:id' do
+    let(:member) { create(:user, :member) }
+    let(:nico_tag) { create(:tag, :nico) }
+
+    it '401 when not logged in' do
+      sign_out
+      patch "/tags/nico/#{nico_tag.id}", params: { tags: 'a b' }
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it '403 when not member' do
+      sign_in_as(create(:user, role: 'guest'))
+      patch "/tags/nico/#{nico_tag.id}", params: { tags: 'a b' }
+      expect(response).to have_http_status(:forbidden)
+    end
+
+    it '400 when target is not nico category' do
+      sign_in_as(member)
+      non_nico = create(:tag, :general)
+      patch "/tags/nico/#{non_nico.id}", params: { tags: 'a b' }
+      expect(response).to have_http_status(:bad_request)
+    end
+  end
+end

backend/spec/requests/posts_spec.rb

@@ -1,30 +1,235 @@
 require 'rails_helper'
+require 'set'
 
 
 RSpec.describe 'Posts API', type: :request do
-  describe 'GET /posts' do
-    it 'returns tags with name in JSON' do
-      tn = TagName.create!(name: 'gen:spec_tag')
-      tag = Tag.create!(tag_name: tn, category: 'general')
+  # 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。
+  before do
+    allow_any_instance_of(Post).to receive(:resized_thumbnail!).and_return(true)
+  end
+
+  def dummy_upload
+    # 中身は何でもいい（加工処理はスタブしてる）
+    Rack::Test::UploadedFile.new(StringIO.new('dummy'), 'image/jpeg', original_filename: 'dummy.jpg')
+  end
+
+  let!(:tag_name) { TagName.create!(name: 'spec_tag') }
+  let!(:tag)      { Tag.create!(tag_name: tag_name, category: 'general') }
 
-      post = Post.create!(title: 'spec post', url: 'https://example.com/spec')
-      PostTag.create!(post: post, tag: tag)
+  let!(:post_record) do
+    Post.create!(title: 'spec post', url: 'https://example.com/spec').tap do |p|
+      PostTag.create!(post: p, tag: tag)
+    end
+  end
 
+  describe 'GET /posts' do
+    it 'returns posts with tag name in JSON' do
       get '/posts'
 
       expect(response).to have_http_status(:ok)
-
-      json = JSON.parse(response.body)
       expect(json).to have_key('posts')
-      expect(json['posts']).to be_a(Array)
+      expect(json['posts']).to be_an(Array)
       expect(json['posts']).not_to be_empty
 
       tags = json['posts'][0]['tags']
-      expect(tags).to be_a(Array)
+      expect(tags).to be_an(Array)
       expect(tags).not_to be_empty
 
+      # Tag は name カラムを持たないので、API 側が methods: [:name] 等で出す必要がある
       expect(tags[0]).to have_key('name')
-      expect(tags[0]['name']).to eq('gen:spec_tag')
+      expect(tags.map { |t| t['name'] }).to include('spec_tag')
+      expect(tags[0]).to include('category')
+    end
+  end
+
+  describe 'GET /posts/:id' do
+    subject(:request) { get "/posts/#{post_id}" }
+
+    context 'when post exists' do
+      let(:post_id) { post_record.id }
+
+      it 'returns post with tag tree + related + viewed' do
+        request
+        expect(response).to have_http_status(:ok)
+
+        expect(json).to include('id' => post_record.id)
+        expect(json).to have_key('tags')
+        expect(json['tags']).to be_an(Array)
+
+        # show は build_tag_tree_for を使うので、tags はツリー形式（children 付き）
+        node = json['tags'][0]
+        expect(node).to include('id', 'name', 'category', 'post_count', 'children')
+        expect(node['name']).to eq('spec_tag')
+
+        expect(json).to have_key('related')
+        expect(json['related']).to be_an(Array)
+
+        expect(json).to have_key('viewed')
+        expect([true, false]).to include(json['viewed'])
+      end
+    end
+
+    context 'when post does not exist' do
+      let(:post_id) { 999_999_999 }
+
+      it 'returns 404' do
+        request
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+  end
+
+  describe 'POST /posts' do
+    let(:member) { create(:user, :member) }
+
+    it '401 when not logged in' do
+      sign_out
+      post '/posts', params: { title: 't', url: 'https://example.com/x', tags: 'a', thumbnail: dummy_upload }
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it '403 when not member' do
+      sign_in_as(create(:user, role: 'guest'))
+      post '/posts', params: { title: 't', url: 'https://example.com/x', tags: 'a', thumbnail: dummy_upload }
+      expect(response).to have_http_status(:forbidden)
+    end
+
+    it '201 and creates post + tags when member' do
+      sign_in_as(member)
+
+      post '/posts', params: {
+        title: 'new post',
+        url: 'https://example.com/new',
+        tags: 'spec_tag', # 既存タグ名を投げる
+        thumbnail: dummy_upload
+      }
+
+      expect(response).to have_http_status(:created)
+      expect(json).to include('id', 'title', 'url')
+
+      # tags が name を含むこと（API 側の serialization が正しいこと）
+      expect(json).to have_key('tags')
+      expect(json['tags']).to be_an(Array)
+      expect(json['tags'][0]).to have_key('name')
+    end
+  end
+
+  describe 'PUT /posts/:id' do
+    let(:member) { create(:user, :member) }
+
+    it '401 when not logged in' do
+      sign_out
+      put "/posts/#{post_record.id}", params: { title: 'updated', tags: 'spec_tag' }
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it '403 when not member' do
+      sign_in_as(create(:user, role: 'guest'))
+      put "/posts/#{post_record.id}", params: { title: 'updated', tags: 'spec_tag' }
+      expect(response).to have_http_status(:forbidden)
+    end
+
+    it '200 and updates title + resync tags when member' do
+      sign_in_as(member)
+
+      # 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')
+
+      put "/posts/#{post_record.id}", params: {
+        title: 'updated title',
+        tags: 'spec_tag_2'
+      }
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to have_key('tags')
+      expect(json['tags']).to be_an(Array)
+
+      # show と同様、update 後レスポンスもツリー形式
+      names = json['tags'].map { |n| n['name'] }
+      expect(names).to include('spec_tag_2')
+    end
+  end
+
+  describe 'GET /posts/random' do
+    it '404 when no posts' do
+      PostTag.delete_all
+      Post.delete_all
+      get '/posts/random'
+      expect(response).to have_http_status(:not_found)
+    end
+
+    it '200 and returns viewed boolean' do
+      get '/posts/random'
+      expect(response).to have_http_status(:ok)
+      expect(json).to have_key('viewed')
+      expect([true, false]).to include(json['viewed'])
+    end
+  end
+
+  describe 'GET /posts/changes' do
+    let(:member) { create(:user, :member) }
+
+    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')
+      pt = PostTag.create!(post: post_record, tag: tag2, created_user: member)
+
+      # remove (discard)
+      pt.discard_by!(member)
+
+      get '/posts/changes', params: { id: post_record.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to include('changes', 'count')
+      expect(json['changes']).to be_an(Array)
+      expect(json['count']).to be >= 2
+
+      types = json['changes'].map { |e| e['change_type'] }.uniq
+      expect(types).to include('add')
+      expect(types).to include('remove')
+    end
+  end
+
+  describe 'POST /posts/:id/viewed' do
+    let(:user) { create(:user) }
+
+    it '401 when not logged in' do
+      sign_out
+      post "/posts/#{ post_record.id }/viewed"
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it '204 and marks viewed when logged in' do
+      sign_in_as(user)
+      post "/posts/#{ post_record.id }/viewed"
+      expect(response).to have_http_status(:no_content)
+
+      expect(user.reload.viewed?(post_record)).to be(true)
+    end
+  end
+
+  describe 'DELETE /posts/:id/unviewed' do
+    let(:user) { create(:user) }
+
+    it '401 when not logged in' do
+      sign_out
+      delete "/posts/#{ post_record.id }/viewed"
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it '204 and unmarks viewed when logged in' do
+      sign_in_as(user)
+
+      # 先に viewed 付けてから外す
+      user.viewed_posts << post_record
+
+      delete "/posts/#{ post_record.id }/viewed"
+      expect(response).to have_http_status(:no_content)
+
+      expect(user.reload.viewed?(post_record)).to be(false)
     end
   end
 end

backend/spec/requests/preview_spec.rb

@@ -0,0 +1,28 @@
+require "rails_helper"
+
+
+RSpec.describe "Preview", type: :request do
+  describe "GET /preview/title" do
+    it "401 unless logged in" do
+      sign_out
+      get "/preview/title", params: { url: "example.com" }
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it "400 when url blank" do
+      sign_in_as(create(:user))
+      get "/preview/title", params: { url: "" }
+      expect(response).to have_http_status(:bad_request)
+    end
+
+    it "returns parsed title (stubbing URI.open)" do
+      sign_in_as(create(:user))
+      fake_html = "<html><head><title>  Hello  </title></head></html>"
+      allow(URI).to receive(:open).and_return(StringIO.new(fake_html))
+
+      get "/preview/title", params: { url: "example.com" }
+      expect(response).to have_http_status(:ok)
+      expect(json["title"]).to eq("Hello")
+    end
+  end
+end

backend/spec/requests/tags_spec.rb

@@ -11,23 +11,50 @@ RSpec.describe 'Tags API', type: :request do
       get '/tags'
 
       expect(response).to have_http_status(:ok)
-      json = JSON.parse(response.body)
 
-      expect(json).to be_a(Array)
+      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')
     end
   end
 
+  describe 'GET /tags/:id' do
+    subject(:request) do
+      get "/tags/#{ tag_id }"
+    end
+
+    let(:tag_id) { tag.id }
+
+    context 'when tag exists' do
+      it 'returns tag with name' do
+        request
+        expect(response).to have_http_status(:ok)
+
+        expect(json).to include(
+            'id'        => tag.id,
+            'name'      => 'spec_tag',
+            'category'  => 'general')
+      end
+    end
+
+    context 'when tag does not exist' do
+      let(:tag_id) { 9_999_999 }
+
+      it 'returns 404' do
+        request
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+  end
+
   describe 'GET /tags/autocomplete' do
     it 'returns matching tags by q' do
       get '/tags/autocomplete', params: { q: 'spec' }
 
       expect(response).to have_http_status(:ok)
-      json = JSON.parse(response.body)
 
-      expect(json).to be_a(Array)
+      expect(json).to be_an(Array)
       expect(json.map { |t| t['name'] }).to include('spec_tag')
     end
   end
@@ -37,12 +64,16 @@ RSpec.describe 'Tags API', type: :request do
       get "/tags/name/#{ CGI.escape('spec_tag') }"
 
       expect(response).to have_http_status(:ok)
-      json = JSON.parse(response.body)
 
       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')
     end
+
+    it 'returns 404 when not found' do
+      get "/tags/name/#{ CGI.escape('nope') }"
+      expect(response).to have_http_status(:not_found)
+    end
   end
 end

backend/spec/requests/users_spec.rb

@@ -0,0 +1,110 @@
+require "rails_helper"
+
+
+RSpec.describe "Users", type: :request do
+  describe "POST /users" do
+    it "creates guest user and returns code" do
+      post "/users"
+      expect(response).to have_http_status(:ok)
+      expect(json["code"]).to be_present
+      expect(json["user"]["role"]).to eq("guest")
+    end
+  end
+
+  describe "POST /users/code/renew" do
+    it "returns 401 when not logged in" do
+      sign_out
+      post "/users/code/renew"
+      expect(response).to have_http_status(:unauthorized)
+    end
+  end
+
+  describe "PUT /users/:id" do
+    let(:user) { create(:user, name: "old-name", role: "guest") }
+
+    it "returns 401 when current_user id mismatch" do
+      sign_in_as(create(:user))
+      put "/users/#{user.id}", params: { name: "new-name" }
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it "returns 400 when name is blank" do
+      sign_in_as(user)
+      put "/users/#{user.id}", params: { name: "   " }
+      expect(response).to have_http_status(:bad_request)
+    end
+
+    it "updates name and returns 201 with user slice" do
+      sign_in_as(user)
+      put "/users/#{user.id}", params: { name: "new-name" }
+
+      expect(response).to have_http_status(:created)
+      expect(json["id"]).to eq(user.id)
+      expect(json["name"]).to eq("new-name")
+
+      user.reload
+      expect(user.name).to eq("new-name")
+    end
+  end
+
+  describe "POST /users/verify" do
+    it "returns valid:false when code not found" do
+      post "/users/verify", params: { code: "nope" }
+      expect(response).to have_http_status(:ok)
+      expect(json["valid"]).to eq(false)
+    end
+
+    it "creates IpAddress and UserIp, and returns valid:true with user slice" do
+      user = create(:user, inheritance_code: SecureRandom.uuid, role: "guest")
+
+      # request.remote_ip を固定
+      allow_any_instance_of(ActionDispatch::Request).to receive(:remote_ip).and_return("203.0.113.10")
+
+      expect {
+        post "/users/verify", params: { code: user.inheritance_code }
+      }.to change(UserIp, :count).by(1)
+
+      expect(response).to have_http_status(:ok)
+      expect(json["valid"]).to eq(true)
+      expect(json["user"]["id"]).to eq(user.id)
+      expect(json["user"]["inheritance_code"]).to eq(user.inheritance_code)
+      expect(json["user"]["role"]).to eq("guest")
+
+      # ついでに IpAddress もできてることを確認（ipの保存形式がバイナリでも count で見れる）
+      expect(IpAddress.count).to be >= 1
+    end
+
+    it "is idempotent for same user+ip (does not create duplicate UserIp)" do
+      user = create(:user, inheritance_code: SecureRandom.uuid, role: "guest")
+      allow_any_instance_of(ActionDispatch::Request).to receive(:remote_ip).and_return("203.0.113.10")
+
+      post "/users/verify", params: { code: user.inheritance_code }
+      expect(response).to have_http_status(:ok)
+
+      expect {
+        post "/users/verify", params: { code: user.inheritance_code }
+      }.not_to change(UserIp, :count)
+
+      expect(response).to have_http_status(:ok)
+      expect(json["valid"]).to eq(true)
+    end
+  end
+
+  describe "GET /users/me" do
+    it "returns 404 when code not found" do
+      get "/users/me", params: { code: "nope" }
+      expect(response).to have_http_status(:not_found)
+    end
+
+    it "returns user slice when found" do
+      user = create(:user, inheritance_code: SecureRandom.uuid, name: "me", role: "guest")
+      get "/users/me", params: { code: user.inheritance_code }
+
+      expect(response).to have_http_status(:ok)
+      expect(json["id"]).to eq(user.id)
+      expect(json["name"]).to eq("me")
+      expect(json["inheritance_code"]).to eq(user.inheritance_code)
+      expect(json["role"]).to eq("guest")
+    end
+  end
+end

backend/spec/requests/wiki_spec.rb

@@ -4,7 +4,7 @@ require 'securerandom'
 
 
 RSpec.describe 'Wiki API', type: :request do
-  let!(:user) { create_user_for_wiki! }
+  let!(:user) { create_member_user! }
 
   let!(:tn) { TagName.create!(name: 'spec_wiki_title') }
   let!(:page) do
@@ -16,9 +16,8 @@ RSpec.describe 'Wiki API', type: :request do
       get '/wiki'
 
       expect(response).to have_http_status(:ok)
-      json = JSON.parse(response.body)
 
-      expect(json).to be_a(Array)
+      expect(json).to be_an(Array)
       expect(json).not_to be_empty
 
       expect(json[0]).to have_key('title')
@@ -26,17 +25,400 @@ RSpec.describe 'Wiki API', type: :request do
     end
   end
 
+  describe 'GET /wiki/:id' do
+    subject(:request) do
+      get "/wiki/#{ page_id }"
+    end
+
+    let(:page_id) { page.id }
+
+    context 'when wiki page exists' do
+      it 'returns wiki page with title' do
+        request
+        expect(response).to have_http_status(:ok)
+
+        expect(json).to include(
+            'id'        => page.id,
+            'title'     => 'spec_wiki_title')
+      end
+    end
+
+    context 'when wiki page does not exist' do
+      let(:page_id) { 9_999_999 }
+
+      it 'returns 404' do
+        request
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+  end
+
+  describe 'POST /wiki' do
+    let(:endpoint) { '/wiki' }
+
+    let(:member) { create(:user, role: 'member') }
+    let(:guest) { create(:user, role: 'guest') }
+
+    def auth_headers(user)
+      { 'X-Transfer-Code' => user.inheritance_code }
+    end
+
+    context 'when not logged in' do
+      it 'returns 401' do
+        post endpoint, params: { title: 'Test', body: 'Hello' }
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when logged in but not member' do
+      it 'returns 403' do
+        post endpoint, params: { title: 'Test', body: 'Hello' }, headers: auth_headers(guest)
+        expect(response).to have_http_status(:forbidden)
+      end
+    end
+
+    context 'when params invalid' do
+      it 'returns 422 when title blank' do
+        post endpoint, params: { title: '', body: 'Hello' }, headers: auth_headers(member)
+        expect(response).to have_http_status(:unprocessable_entity)
+      end
+
+      it 'returns 422 when body blank' do
+        post endpoint, params: { title: 'Test', body: '' }, headers: auth_headers(member)
+        expect(response).to have_http_status(:unprocessable_entity)
+      end
+    end
+
+    context 'when success' do
+      it 'creates wiki_page and first content revision' do
+        expect do
+          post endpoint, params: { title: 'TestPage', body: "a\nb\nc", message: 'init' },
+                         headers: auth_headers(member)
+        end
+            .to change(WikiPage, :count).by(1)
+            .and change(WikiRevision, :count).by(1)
+
+        expect(response).to have_http_status(:created)
+
+        page_id = json.fetch('id')
+        expect(json.fetch('title')).to eq('TestPage')
+
+        page = WikiPage.find(page_id)
+        rev = page.current_revision
+        expect(rev).to be_present
+        expect(rev).to be_content
+        expect(rev.message).to eq('init')
+
+        # body が復元できること
+        expect(page.body).to eq("a\nb\nc")
+
+        # 行数とリレーションの整合
+        expect(rev.lines_count).to eq(3)
+        expect(rev.wiki_revision_lines.order(:position).pluck(:position)).to eq([0, 1, 2])
+        expect(rev.wiki_lines.pluck(:body)).to match_array(%w[a b c])
+      end
+
+      it 'reuses existing WikiLine rows by sha256' do
+        # 先に同じ行を作っておく
+        WikiLine.create!(sha256: Digest::SHA256.hexdigest('a'), body: 'a', created_at: Time.current, updated_at: Time.current)
+
+        post endpoint,
+             params: { title: 'Reuse', body: "a\na" },
+             headers: auth_headers(member)
+
+        page = WikiPage.find(JSON.parse(response.body).fetch('id'))
+        rev = page.current_revision
+        expect(rev.lines_count).to eq(2)
+
+        # "a" の WikiLine が増殖しない（1行のはず）
+        expect(WikiLine.where(body: 'a').count).to eq(1)
+      end
+    end
+  end
+
+  describe 'PUT /wiki/:id' do
+    let(:member) { create(:user, role: 'member', inheritance_code: SecureRandom.hex(16)) }
+    let(:guest)  { create(:user, role: 'guest',  inheritance_code: SecureRandom.hex(16)) }
+
+    def auth_headers(user)
+      { 'X-Transfer-Code' => user.inheritance_code }
+    end
+
+    #let!(:page) { create(:wiki_page, title: 'TestPage') }
+    let!(:page) do
+      build(:wiki_page, title: 'TestPage').tap do |p|
+        puts p.errors.full_messages unless p.valid?
+        p.save!
+      end
+    end
+
+    before do
+      # 初期版を 1 つ作っておく（更新が“2版目”になるように）
+      Wiki::Commit.content!(page: page, body: "a\nb", created_user: member, message: 'init')
+    end
+
+    context 'when not logged in' do
+      it 'returns 401' do
+        put "/wiki/#{page.id}", params: { title: 'TestPage', body: 'x' }
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when logged in but not member' do
+      it 'returns 403' do
+        put "/wiki/#{page.id}",
+            params: { title: 'TestPage', body: 'x' },
+            headers: auth_headers(guest)
+        expect(response).to have_http_status(:forbidden)
+      end
+    end
+
+    context 'when params invalid' do
+      it 'returns 422 when body blank' do
+        put "/wiki/#{page.id}",
+            params: { title: 'TestPage', body: '' },
+            headers: auth_headers(member)
+        expect(response).to have_http_status(:unprocessable_entity)
+      end
+
+      it 'returns 422 when title mismatched (if you forbid rename here)' do
+        put "/wiki/#{page.id}",
+            params: { title: 'OtherTitle', body: 'x' },
+            headers: auth_headers(member)
+        # 君の controller 例だと title 変更は 422 にしてた
+        expect(response).to have_http_status(:unprocessable_entity)
+      end
+    end
+
+    context 'when success' do
+      it 'creates new revision and returns 200' do
+        current_id = page.wiki_revisions.maximum(:id)
+
+        expect do
+          put "/wiki/#{page.id}",
+              params: { title: 'TestPage', body: "x\ny", message: 'edit', base_revision_id: current_id },
+              headers: auth_headers(member)
+        end.to change(WikiRevision, :count).by(1)
+
+        expect(response).to have_http_status(:ok)
+
+        page.reload
+        rev = page.current_revision
+        expect(rev).to be_content
+        expect(rev.message).to eq('edit')
+        expect(page.body).to eq("x\ny")
+        expect(rev.base_revision_id).to eq(current_id)
+      end
+    end
+
+    # TODO: コンフリクト未実装のため，実装したらコメント外す．
+    # context 'when conflict' do
+    #   it 'returns 409 when base_revision_id mismatches' do
+    #     # 先に別ユーザ（同じ member でもOK）が 1 回更新して先頭を進める
+    #     Wiki::Commit.content!(page: page, body: "zzz", created_user: member, message: 'other edit')
+    #     page.reload
+
+    #     stale_id = page.wiki_revisions.order(:id).first.id # わざと古い id
+    #     put "/wiki/#{page.id}",
+    #         params: { title: 'TestPage', body: 'x', base_revision_id: stale_id },
+    #         headers: auth_headers(member)
+
+    #     expect(response).to have_http_status(:conflict)
+    #     json = JSON.parse(response.body)
+    #     expect(json['error']).to eq('conflict')
+    #   end
+    # end
+
+    context 'when page not found' do
+      it 'returns 404' do
+        put "/wiki/99999999",
+            params: { title: 'X', body: 'x' },
+            headers: auth_headers(member)
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+  end
+
   describe 'GET /wiki/title/:title' do
     it 'returns wiki page by title' do
       get "/wiki/title/#{CGI.escape('spec_wiki_title')}"
 
       expect(response).to have_http_status(:ok)
-      json = JSON.parse(response.body)
 
       expect(json).to have_key('id')
       expect(json).to have_key('title')
       expect(json['id']).to eq(page.id)
       expect(json['title']).to eq('spec_wiki_title')
     end
+
+    it 'returns 404 when not found' do
+      get "/wiki/title/#{ CGI.escape('nope') }"
+      expect(response).to have_http_status(:not_found)
+    end
+  end
+
+  describe 'GET /wiki/search' do
+    before do
+      # 追加で検索ヒット用
+      TagName.create!(name: 'spec_wiki_title_2')
+      WikiPage.create!(tag_name: TagName.find_by!(name: 'spec_wiki_title_2'),
+                       created_user: user, updated_user: user)
+
+      TagName.create!(name: 'unrelated_title')
+      WikiPage.create!(tag_name: TagName.find_by!(name: 'unrelated_title'),
+                       created_user: user, updated_user: user)
+    end
+
+    it 'returns up to 20 pages filtered by title like' do
+      get "/wiki/search?title=#{CGI.escape('spec_wiki')}"
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to be_an(Array)
+
+      titles = json.map { |p| p['title'] }
+      expect(titles).to include('spec_wiki_title', 'spec_wiki_title_2')
+      expect(titles).not_to include('unrelated_title')
+    end
+
+    it 'returns all when title param is blank' do
+      get "/wiki/search?title=#{CGI.escape('')}"
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to be_an(Array)
+      expect(json.map { |p| p['title'] }).to include('spec_wiki_title')
+    end
+  end
+
+  describe 'GET /wiki/changes' do
+    let!(:rev1) do
+      Wiki::Commit.content!(page: page, body: "a\nb", created_user: user, message: 'r1')
+      page.current_revision
+    end
+
+    let!(:rev2) do
+      Wiki::Commit.content!(page: page, body: "a\nc", created_user: user, message: 'r2')
+      page.current_revision
+    end
+
+    it 'returns latest revisions (optionally filtered by page id)' do
+      get "/wiki/changes?id=#{page.id}"
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to be_an(Array)
+      expect(json).not_to be_empty
+
+      top = json.first
+      expect(top).to include(
+        'revision_id' => rev2.id,
+        'pred' => rev2.base_revision_id,
+        'succ' => nil,
+        'kind' => 'content',
+        'message' => 'r2'
+      )
+      expect(top['wiki_page']).to include('id' => page.id, 'title' => 'spec_wiki_title')
+      expect(top['user']).to include('id' => user.id, 'name' => user.name)
+      expect(top).to have_key('timestamp')
+
+      # order desc をざっくり担保
+      ids = json.map { |x| x['revision_id'] }
+      expect(ids).to eq(ids.sort.reverse)
+    end
+
+    it 'returns empty array when page has no revisions and filtered by id' do
+      # 別ページを作って revision 無し
+      tn2 = TagName.create!(name: 'spec_no_rev')
+      p2 = WikiPage.create!(tag_name: tn2, created_user: user, updated_user: user)
+
+      get "/wiki/changes?id=#{p2.id}"
+      expect(response).to have_http_status(:ok)
+      expect(json).to eq([])
+    end
+  end
+
+  describe 'GET /wiki/title/:title/exists' do
+    it 'returns 204 when exists' do
+      get "/wiki/title/#{CGI.escape('spec_wiki_title')}/exists"
+      expect(response).to have_http_status(:no_content)
+      expect(response.body).to be_empty
+    end
+
+    it 'returns 404 when not exists' do
+      get "/wiki/title/#{CGI.escape('nope')}/exists"
+      expect(response).to have_http_status(:not_found)
+    end
+  end
+
+  describe 'GET /wiki/:id/exists' do
+    it 'returns 204 when exists' do
+      get "/wiki/#{page.id}/exists"
+      expect(response).to have_http_status(:no_content)
+      expect(response.body).to be_empty
+    end
+
+    it 'returns 404 when not exists' do
+      get "/wiki/99999999/exists"
+      expect(response).to have_http_status(:not_found)
+    end
+  end
+
+  describe 'GET /wiki/:id/diff' do
+    let!(:rev_a) do
+      Wiki::Commit.content!(page: page, body: "a\nb\nc", created_user: user, message: 'A')
+      page.current_revision
+    end
+
+    let!(:rev_b) do
+      Wiki::Commit.content!(page: page, body: "a\nx\nc", created_user: user, message: 'B')
+      page.current_revision
+    end
+
+    it 'returns diff json between revisions' do
+      get "/wiki/#{page.id}/diff?from=#{rev_a.id}&to=#{rev_b.id}"
+
+      expect(response).to have_http_status(:ok)
+
+      expect(json).to include(
+        'wiki_page_id' => page.id,
+        'title' => 'spec_wiki_title',
+        'older_revision_id' => rev_a.id,
+        'newer_revision_id' => rev_b.id
+      )
+      expect(json['diff']).to be_an(Array)
+      # ざっくり「b が消えて x が増えた」が含まれることを確認
+      types = json['diff'].map { |x| x['type'] }
+      expect(types).to include('removed', 'added').or include('removed').and include('added')
+    end
+
+    it 'uses latest as "to" when to is omitted' do
+      get "/wiki/#{page.id}/diff?from=#{rev_a.id}"
+
+      expect(response).to have_http_status(:ok)
+      expect(json['older_revision_id']).to eq(rev_a.id)
+      expect(json['newer_revision_id']).to eq(page.current_revision.id)
+    end
+
+    it 'returns 422 when "to" is redirect revision' do
+      # redirect revision を作る
+      tn2 = TagName.create!(name: 'redirect_target')
+      target = WikiPage.create!(tag_name: tn2, created_user: user, updated_user: user)
+
+      Wiki::Commit.redirect!(page: page, redirect_page: target, created_user: user, message: 'redir')
+      redirect_rev = page.current_revision
+      expect(redirect_rev).to be_redirect
+
+      get "/wiki/#{page.id}/diff?from=#{rev_a.id}&to=#{redirect_rev.id}"
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+
+    it 'returns 422 when "from" is redirect revision' do
+      tn2 = TagName.create!(name: 'redirect_target2')
+      target = WikiPage.create!(tag_name: tn2, created_user: user, updated_user: user)
+
+      Wiki::Commit.redirect!(page: page, redirect_page: target, created_user: user, message: 'redir2')
+      redirect_rev = page.current_revision
+
+      get "/wiki/#{page.id}/diff?from=#{redirect_rev.id}&to=#{rev_b.id}"
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
   end
 end

backend/spec/support/auth_helper.rb

@@ -0,0 +1,11 @@
+module AuthHelper
+  def sign_in_as(user)
+    allow_any_instance_of(ApplicationController)
+      .to receive(:current_user).and_return(user)
+  end
+
+  def sign_out
+    allow_any_instance_of(ApplicationController)
+      .to receive(:current_user).and_return(nil)
+  end
+end

backend/spec/support/json_helper.rb

@@ -0,0 +1,5 @@
+module JsonHelper
+  def json
+    JSON.parse(response.body)
+  end
+end

backend/spec/support/rake.rb

@@ -0,0 +1,21 @@
+require "rake"
+
+
+module RakeTaskHelper
+  # Railsの rake task を一度だけロードする
+  def load_rails_tasks!
+    return if defined?(@rails_tasks_loaded) && @rails_tasks_loaded
+    @rails_tasks_loaded = true
+
+    Rake.application = Rake::Application.new
+    Rails.application.load_tasks
+  end
+
+  def run_rake_task(full_name)
+    load_rails_tasks!
+
+    task = Rake::Task[full_name]  # ここは rake[...] じゃなくて良い
+    task.reenable
+    task.invoke
+  end
+end

backend/spec/tasks/nico_sync_spec.rb

@@ -0,0 +1,86 @@
+require "rails_helper"
+
+
+RSpec.describe "nico:sync" do
+  def stub_python(json_array)
+    status = instance_double(Process::Status, success?: true)
+    allow(Open3).to receive(:capture3).and_return([json_array.to_json, "", status])
+  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 }
+  end
+
+  def link_nico_to_tag!(nico_tag, tag)
+    # NicoTagRelation がある前提（君の model からそう見える）
+    NicoTagRelation.create!(nico_tag_id: nico_tag.id, tag_id: tag.id)
+  end
+
+  it "既存 post を見つけて、nico tag と linked tag を追加し、差分が出たら bot を付ける" do
+    # 既存 post（正規表現で拾われるURL）
+    post = Post.create!(title: "old", url: "https://www.nicovideo.jp/watch/sm9", uploaded_user: nil)
+
+    # 既存の非nicoタグ（kept_non_nico_ids）
+    kept_general = create_tag!("spec_kept", category: "general")
+    PostTag.create!(post: post, tag: kept_general)
+
+    # 追加される linked tag を準備（nico tag に紐付く一般タグ）
+    linked = create_tag!("spec_linked", category: "general")
+    nico = create_tag!("nico:AAA", category: "nico")
+    link_nico_to_tag!(nico, linked)
+
+    # bot / tagme は task 内で使うので作っておく（Tag.bot/tagme がある前提）
+    Tag.bot
+    Tag.tagme
+
+    # pythonの出力（AAA が付く）
+    stub_python([{ "code" => "sm9", "title" => "t", "tags" => ["AAA"] }])
+
+    # 外部HTTPは今回「既存 post なので呼ばれない」はずだが、念のため塞ぐ
+    allow(URI).to receive(:open).and_return(StringIO.new("<html></html>"))
+
+    run_rake_task("nico:sync")
+
+    post.reload
+    active_tag_names = post.tags.joins(:tag_name).pluck("tag_names.name")
+
+    expect(active_tag_names).to include("spec_kept")
+    expect(active_tag_names).to include("nico:AAA")
+    expect(active_tag_names).to include("spec_linked")
+
+    # 差分が出るので bot が付く（kept_non_nico_ids != desired_non_nico_ids）
+    expect(active_tag_names).to include("bot操作")
+  end
+
+  it "既存 post にあった古い nico tag は active から外され、履歴として discard される" do
+    post = Post.create!(title: "old", url: "https://www.nicovideo.jp/watch/sm9", uploaded_user: nil)
+
+    # 旧nicoタグ（今回の同期結果に含まれない）
+    old_nico = create_tag!("nico:OLD", category: "nico")
+    old_pt = PostTag.create!(post: post, tag: old_nico)
+    expect(old_pt.discarded_at).to be_nil
+
+    # 今回は NEW のみ欲しい
+    new_nico = create_tag!("nico:NEW", category: "nico")
+
+    # bot/tagme 念のため
+    Tag.bot
+    Tag.tagme
+
+    stub_python([{ "code" => "sm9", "title" => "t", "tags" => ["NEW"] }])
+    allow(URI).to receive(:open).and_return(StringIO.new("<html></html>"))
+
+    run_rake_task("nico:sync")
+
+    # OLD は active から外れる（discarded_at が入る）
+    old_pts = PostTag.where(post_id: post.id, tag_id: old_nico.id).order(:id).to_a
+    expect(old_pts.last.discarded_at).to be_present
+
+    # NEW は active にいる
+    post.reload
+    active_names = post.tags.joins(:tag_name).pluck("tag_names.name")
+    expect(active_names).to include("nico:NEW")
+    expect(active_names).not_to include("nico:OLD")
+  end
+end