Merge remote-tracking branch 'origin/main' into feature/047

#314

#314

#314

#314

#314

Co-authored-by: miteruzo <miteruzo@naver.com>
Reviewed-on: #340

backend/app/controllers/wiki_assets_controller.rb

@@ -0,0 +1,39 @@
+require 'digest'
+
+
+class WikiAssetsController < ApplicationController
+  def index
+    page_id = params[:wiki_page_id].to_i
+    page = WikiPage.find_by(id: page_id)
+    return head :not_found unless page
+
+    render json: WikiAssetRepr.many(page.assets)
+  end
+
+  def create
+    return head :unauthorized unless current_user
+    return head :forbidden unless current_user.gte_member?
+
+    wiki_page_id = params[:wiki_page_id].to_i
+    page = WikiPage.find_by(id: wiki_page_id)
+    return head :not_found unless page
+
+    file = params[:file]
+    return head :bad_request if file.blank?
+
+    asset = nil
+    page.with_lock do
+      no = page.next_asset_no
+      alt_text = params[:alt_text].presence
+      sha256 = Digest::SHA256.file(file.tempfile.path).digest
+
+      asset = WikiAsset.new(wiki_page_id:, no:, alt_text:, sha256:, created_by_user: current_user)
+      asset.file.attach(file)
+      asset.save!
+
+      page.update!(next_asset_no: no + 1)
+    end
+
+    render json: WikiAssetRepr.base(asset)
+  end
+end

backend/app/controllers/wiki_pages_controller.rb

@@ -109,7 +109,7 @@ class WikiPagesController < ApplicationController
     return head :unauthorized unless current_user
     return head :forbidden unless current_user.gte_member?
 
-    title = params[:title]&.strip
+    title = params[:title].to_s.strip
     body = params[:body].to_s
 
     return head :unprocessable_entity if title.blank? || body.blank?
@@ -143,7 +143,14 @@ class WikiPagesController < ApplicationController
       end
     end
 
-    head :ok
+    message = params[:message].presence
+    Wiki::Commit.content!(page:,
+                          body:,
+                          created_user: current_user,
+                          message:,
+                          base_revision_id:)
+
+    render json: WikiPageRepr.base(page).merge(body:)
   end
 
   def search

backend/app/models/ip_address.rb

@@ -1,7 +1,14 @@
 class IpAddress < ApplicationRecord
   validates :ip_address, presence: true, length: { maximum: 16 }
-  validates :banned, inclusion: { in: [true, false] }
 
   has_many :user_ips, dependent: :destroy
   has_many :users, through: :user_ips
+
+  def banned? = banned_at?
+  def banned = banned?
+
+  def banned= value
+    bool = ActiveModel::Type::Boolean.new.cast(value)
+    self.banned_at = bool ? banned_at || Time.current : nil
+  end
 end

backend/app/models/post.rb

@@ -1,7 +1,6 @@
 class Post < ApplicationRecord
   require 'mini_magick'
 
-  belongs_to :parent, class_name: 'Post', optional: true, foreign_key: 'parent_id'
   belongs_to :uploaded_user, class_name: 'User', optional: true
 
   has_many :post_tags, dependent: :destroy, inverse_of: :post

backend/app/models/post_version.rb

@@ -2,7 +2,6 @@ class PostVersion < ApplicationRecord
   include VersionRecord
 
   belongs_to :post
-  belongs_to :parent, class_name: 'Post', optional: true
 
   validates :url, presence: true
 

backend/app/models/tag.rb

@@ -84,6 +84,7 @@ class Tag < ApplicationRecord
   def self.no_deerjikist = find_or_create_by_tag_name!('ニジラー情報不詳', category: :meta)
   def self.video = find_or_create_by_tag_name!('動画', category: :meta)
   def self.niconico = find_or_create_by_tag_name!('ニコニコ', category: :meta)
+  def self.youtube = find_or_create_by_tag_name!('YouTube', category: :meta)
 
   def self.normalise_tags tag_names, with_tagme: true,
                                      with_no_deerjikist: true,

backend/app/models/user.rb

@@ -4,7 +4,6 @@ class User < ApplicationRecord
   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 :created_posts,
            class_name: 'Post', foreign_key: :uploaded_user_id, dependent: :nullify
@@ -18,6 +17,14 @@ class User < ApplicationRecord
   has_many :updated_wiki_pages,
            class_name: 'WikiPage', foreign_key: :updated_user_id, dependent: :nullify
 
+  def banned? = banned_at?
+  def banned = banned?
+
+  def banned= value
+    bool = ActiveModel::Type::Boolean.new.cast(value)
+    self.banned_at = bool ? (banned_at || Time.current) : nil
+  end
+
   def viewed?(post) = user_post_views.exists?(post_id: post.id)
   def gte_member? = member? || admin?
 end

backend/app/models/wiki_asset.rb

@@ -0,0 +1,12 @@
+class WikiAsset < ApplicationRecord
+  belongs_to :wiki_page
+  belongs_to :created_by_user, class_name: 'User'
+
+  has_one_attached :file
+
+  validates :file, presence: true
+
+  def url
+    Rails.application.routes.url_helpers.rails_blob_url(file, only_path: true)
+  end
+end

backend/app/models/wiki_page.rb

@@ -13,6 +13,8 @@ class WikiPage < ApplicationRecord
            foreign_key: :redirect_page_id,
            dependent: :nullify
 
+  has_many :assets, class_name: 'WikiAsset', dependent: :destroy
+
   has_many :wiki_versions
 
   belongs_to :tag_name

backend/app/representations/wiki_asset_repr.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+
+module WikiAssetRepr
+  BASE = { only: [:wiki_page_id, :no], methods: [:url] }.freeze
+
+  module_function
+
+  def base wiki_asset
+    wiki_asset.as_json(BASE)
+  end
+
+  def many wiki_assets
+    wiki_assets.map { |a| base(a) }
+  end
+end

backend/app/services/post_version_recorder.rb

@@ -24,7 +24,6 @@ class PostVersionRecorder < VersionRecorder
       url: @record.url,
       thumbnail_base: @record.thumbnail_base,
       tags: @record.snapshot_tag_names.join(' '),
-      parent_id: @record.parent_id,
       original_created_from: @record.original_created_from,
       original_created_before: @record.original_created_before }
   end

backend/app/services/youtube/api_client.rb

@@ -0,0 +1,73 @@
+require 'json'
+require 'net/http'
+require 'uri'
+
+
+module Youtube
+  class ApiClient
+    ENDPOINT = 'https://www.googleapis.com/youtube/v3'
+
+    def initialize api_key: ENV.fetch('YOUTUBE_API_KEY')
+      @api_key = api_key
+    end
+
+    def search_videos q:, published_after: nil, published_before: nil, page_token: nil
+      get_json('/search', {
+          part:           'snippet',
+          type:           'video',
+          q:,
+          order:          'date',
+          maxResults:     50,
+          regionCode:     'JP',
+          relevanceLanguage: 'ja',
+          publishedAfter: published_after&.iso8601,
+          publishedBefore: published_before&.iso8601,
+          pageToken:      page_token }.compact)
+    end
+
+    def videos ids
+      return { 'items' => [] } if ids.empty?
+
+      get_json('/videos', part: 'snippet,status,contentDetails', id: ids.join(','))
+    end
+
+    def playlist_items playlist_id:, page_token: nil
+      get_json('/playlistItems', {
+          part:       'snippet,contentDetails,status',
+          playlistId: playlist_id,
+          maxResults: 50,
+          pageToken:  page_token }.compact)
+    end
+
+    def channel id: nil, handle: nil
+      raise ArgumentError, 'id or handle is required' if id.present? == handle.present?
+
+      params = { part: 'snippet,contentDetails' }
+      params[:id] = id if id.present?
+      params[:forHandle] = handle if handle.present?
+
+      get_json('/channels', params)
+    end
+
+    private
+
+    def get_json path, params
+      uri = URI(ENDPOINT + path)
+      uri.query = URI.encode_www_form(params.merge(key: @api_key))
+
+      response = Net::HTTP.start(uri.host,
+                                 uri.port,
+                                 use_ssl: true,
+                                 open_timeout: 10,
+                                 read_timeout: 30) do |http|
+        http.get(uri)
+      end
+
+      unless response.is_a?(Net::HTTPSuccess)
+        raise "YouTube API error: #{ response.code } #{ response.body }"
+      end
+
+      JSON.parse(response.body)
+    end
+  end
+end

backend/app/services/youtube/sync.rb

@@ -0,0 +1,168 @@
+require 'open-uri'
+require 'set'
+require 'time'
+
+
+module Youtube
+  class Sync
+    def initialize client: ApiClient.new
+      @client = client
+    end
+
+    def sync!
+      video_ids = discover_video_ids
+      return if video_ids.empty?
+
+      video_ids.each_slice(50) do |ids|
+        @client.videos(ids).fetch('items', []).each do |item|
+          sync_video!(VideoItem.new(item))
+        end
+      end
+    end
+
+    private
+
+    def discover_video_ids
+      ids = Set.new
+
+      query_terms.each do |q|
+        response = @client.search_videos(q:, published_after: sync_since)
+
+        response.fetch('items', []).each do |item|
+          video_id = item.dig('id', 'videoId')
+          ids << video_id if video_id.present?
+        end
+      end
+
+      playlist_ids.each do |playlist_id|
+        each_playlist_item(playlist_id) do |item|
+          video_id = item.dig('contentDetails', 'videoId')
+          video_id ||= item.dig('snippet', 'resourceId', 'videoId')
+
+          ids << video_id if video_id.present?
+        end
+      end
+
+      ids.to_a
+    end
+
+    def sync_video! video
+      post = Post.where('url REGEXP ?', youtube_url_regexp(video.id)).first
+
+      original_created_from = video.published_at.change(sec: 0)
+      original_created_before = original_created_from + 1.minute
+
+      post_created = false
+      post_changed = false
+
+      if post
+        post.assign_attributes(title: video.title,
+                               original_created_from:,
+                               original_created_before:,
+                               thumbnail_base: video.thumbnail_url)
+
+        post_changed = post.changed?
+        post.save! if post_changed
+
+        attach_thumbnail_if_needed!(post, video.thumbnail_url)
+      else
+        post_created = true
+        post = Post.create!(
+            title: video.title,
+            url: video.url,
+            thumbnail_base: video.thumbnail_url,
+            uploaded_user_id: nil,
+            original_created_from:,
+            original_created_before:)
+
+        attach_thumbnail_if_needed!(post, video.thumbnail_url)
+
+        sync_post_tags!(post, [Tag.tagme.id, Tag.bot.id, Tag.youtube.id, Tag.video.id])
+      end
+
+      kept_tag_ids = post.tags.pluck(:id).to_set
+      desired_tag_ids = kept_tag_ids.to_a
+
+      deerjikist = Deerjikist.find_by(platform: :youtube, code: video.channel_id)
+      if deerjikist
+        desired_tag_ids.delete(Tag.no_deerjikist.id)
+        desired_tag_ids << deerjikist.tag_id
+      elsif post.tags.where(category: :deerjikist).none?
+        desired_tag_ids << Tag.no_deerjikist.id
+      end
+
+      desired_tag_ids.uniq!
+
+      sync_post_tags!(post, desired_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_tag_ids.to_set
+        PostVersionRecorder.ensure_snapshot!(post, created_by_user: nil)
+        PostVersionRecorder.record!(post:, event_type: :update, created_by_user: nil)
+      end
+    end
+
+    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_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
+          PostTag.create!(post:, tag:)
+        rescue ActiveRecord::RecordNotUnique
+          ;
+        end
+      end
+
+      PostTag.where(post_id: post.id, tag_id: to_remove.to_a).kept.find_each do |pt|
+        pt.discard_by!(nil)
+      end
+    end
+
+    def attach_thumbnail_if_needed! post, thumbnail_url
+      return if post.thumbnail.attached?
+      return if thumbnail_url.blank?
+
+      post.thumbnail.attach(
+          io:           URI.open(thumbnail_url),
+          filename:     File.basename(URI.parse(thumbnail_url).path),
+          content_type: 'image/jpeg')
+
+      post.resized_thumbnail!
+    end
+
+    def youtube_url_regexp id
+      escaped = Regexp.escape(id)
+      "(youtube\\.com/watch\\?v=#{ escaped }|youtu\\.be/#{ escaped })([^A-Za-z0-9_-]|$)"
+    end
+
+    def query_terms = ['ぼざろクリーチャーシリーズ', '伊地知ニジカ', '伊地知虹鹿']
+
+    def playlist_ids
+      ['PLrOch4zHkI5vu29b-f9umUQQ4tQkuWLPX',
+       'PLrOch4zHkI5vOK0RaytQq6PbucxQkkL0K',
+       'PLrOch4zHkI5tdwm9vSegiDQJOM-hgpcOC']
+    end
+
+    def sync_since = 14.days.ago
+
+    def each_playlist_item playlist_id
+      page_token = nil
+
+      loop do
+        response = @client.playlist_items(playlist_id:, page_token:)
+
+        response.fetch('items', []).each do |item|
+          yield item
+        end
+
+        page_token = response['nextPageToken']
+        break if page_token.blank?
+      end
+    end
+  end
+end

backend/app/services/youtube/video_item.rb

@@ -0,0 +1,32 @@
+require 'time'
+
+
+module Youtube
+  class VideoItem
+    attr_reader :id, :title, :channel_id, :published_at, :thumbnail_url, :raw_tags
+
+    def initialize item
+      snippet = item.fetch('snippet')
+
+      @id = item.fetch('id')
+      @title = snippet['title']
+      @channel_id = snippet['channelId']
+      @published_at = Time.iso8601(snippet['publishedAt'])
+      @thumbnail_url = pick_thumbnail(snippet['thumbnails'] || { })
+      @raw_tags = snippet['tags'] || []
+    end
+
+    def url = "https://www.youtube.com/watch?v=#{ @id }"
+
+    private
+
+    def pick_thumbnail thumbnails
+      ['maxres', 'standard', 'high', 'medium', 'default'].each do |key|
+        url = thumbnails.dig(key, 'url')
+        return url if url.present?
+      end
+
+      nil
+    end
+  end
+end

backend/config/routes.rb

@@ -47,6 +47,8 @@ Rails.application.routes.draw do
       get :exists
       get :diff
     end
+
+    resources :assets, controller: :wiki_assets, only: [:index, :create]
   end
 
   resources :posts, only: [:index, :show, :create, :update] do

backend/config/schedule.rb

@@ -17,3 +17,11 @@ every 1.day, at: '0:00 am' do
   rake 'post_similarity:calc', environment: 'production'
   rake 'tag_similarity:calc', environment: 'production'
 end
+
+every 1.day, at: '7:50 am' do
+  rake 'nico:export', environment: 'production'
+end
+
+every :hour do
+  rake 'post:sync', environment: 'production'
+end

backend/db/migrate/20260323192300_create_wiki_assets.rb

@@ -0,0 +1,17 @@
+class CreateWikiAssets < ActiveRecord::Migration[8.0]
+  def change
+    create_table :wiki_assets do |t|
+      t.references :wiki_page, null: false, foreign_key: true, index: false
+      t.integer :no, null: false
+      t.string :alt_text
+      t.column :sha256, 'binary(32)', null: false
+      t.references :created_by_user, null: false, foreign_key: { to_table: :users }
+      t.timestamps
+    end
+
+    add_index :wiki_assets, [:wiki_page_id, :sha256], unique: true
+    add_index :wiki_assets, [:wiki_page_id, :no], unique: true
+
+    add_column :wiki_pages, :next_asset_no, :integer, null: false, default: 1
+  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_04_26_120600) do
+ActiveRecord::Schema[8.0].define(version: 2026_05_01_153900) 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
@@ -50,9 +50,10 @@ ActiveRecord::Schema[8.0].define(version: 2026_04_26_120600) do
 
   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
+    t.datetime "banned_at"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.index ["banned_at"], name: "index_ip_addresses_on_banned_at"
     t.index ["ip_address"], name: "index_ip_addresses_on_ip_address", unique: true
   end
 
@@ -119,6 +120,15 @@ ActiveRecord::Schema[8.0].define(version: 2026_04_26_120600) do
     t.check_constraint "`version_no` > 0", name: "nico_tag_versions_version_no_positive"
   end
 
+  create_table "post_implications", primary_key: ["post_id", "parent_post_id"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "post_id", null: false
+    t.bigint "parent_post_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["parent_post_id"], name: "index_post_implications_on_parent_post_id"
+    t.check_constraint "`post_id` <> `parent_post_id`", name: "chk_post_implications_no_self"
+  end
+
   create_table "post_similarities", primary_key: ["post_id", "target_post_id"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "post_id", null: false
     t.bigint "target_post_id", null: false
@@ -155,13 +165,12 @@ ActiveRecord::Schema[8.0].define(version: 2026_04_26_120600) do
     t.string "url", limit: 768, null: false
     t.string "thumbnail_base", limit: 2000
     t.text "tags", null: false
-    t.bigint "parent_id"
+    t.text "parent_post_ids", null: false
     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"
@@ -172,13 +181,11 @@ ActiveRecord::Schema[8.0].define(version: 2026_04_26_120600) do
     t.string "title"
     t.string "url", limit: 768, null: false
     t.string "thumbnail_base", limit: 2000
-    t.bigint "parent_id"
     t.bigint "uploaded_user_id"
     t.datetime "created_at", null: false
     t.datetime "original_created_from"
     t.datetime "original_created_before"
     t.datetime "updated_at", null: false
-    t.index ["parent_id"], name: "index_posts_on_parent_id"
     t.index ["uploaded_user_id"], name: "index_posts_on_uploaded_user_id"
     t.index ["url"], name: "index_posts_on_url", unique: true
   end
@@ -326,9 +333,10 @@ ActiveRecord::Schema[8.0].define(version: 2026_04_26_120600) do
     t.string "name"
     t.string "inheritance_code", limit: 64, null: false
     t.string "role", null: false
-    t.boolean "banned", default: false, null: false
+    t.datetime "banned_at"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.index ["banned_at"], name: "index_users_on_banned_at"
   end
 
   create_table "wiki_assets", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
@@ -428,6 +436,8 @@ ActiveRecord::Schema[8.0].define(version: 2026_04_26_120600) do
   add_foreign_key "nico_tag_relations", "tags", column: "nico_tag_id"
   add_foreign_key "nico_tag_versions", "tags"
   add_foreign_key "nico_tag_versions", "users", column: "created_by_user_id"
+  add_foreign_key "post_implications", "posts"
+  add_foreign_key "post_implications", "posts", column: "parent_post_id"
   add_foreign_key "post_similarities", "posts"
   add_foreign_key "post_similarities", "posts", column: "target_post_id"
   add_foreign_key "post_tags", "posts"
@@ -435,9 +445,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_04_26_120600) do
   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"
   add_foreign_key "tag_implications", "tags"

backend/lib/tasks/sync_posts.rake

@@ -0,0 +1,6 @@
+namespace :post do
+  desc '投稿同期（ニコニコ以外）'
+  task sync: :environment do
+    Youtube::Sync.new.sync!
+  end
+end

backend/spec/models/post_version_spec.rb

@@ -19,7 +19,6 @@ RSpec.describe PostVersion, type: :model do
       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,

backend/spec/models/tag_spec.rb

@@ -161,7 +161,6 @@ RSpec.describe Tag, type: :model do
         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,

backend/spec/requests/posts_spec.rb

@@ -782,7 +782,6 @@ RSpec.describe 'Posts API', type: :request do
         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,
@@ -1024,7 +1023,6 @@ RSpec.describe 'Posts API', type: :request do
         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,

backend/spec/requests/wiki_assets_spec.rb

@@ -0,0 +1,191 @@
+require 'digest'
+require 'rails_helper'
+require 'stringio'
+
+
+RSpec.describe 'WikiAssets API', type: :request do
+  def dummy_upload(content = 'dummy-image', filename: 'dummy.png', content_type: 'image/png')
+    Rack::Test::UploadedFile.new(StringIO.new(content),
+                                 content_type,
+                                 original_filename: filename)
+  end
+
+  let(:member) { create(:user, :member, name: 'member user') }
+  let(:guest)  { create(:user, name: 'guest user') }
+
+  let!(:tag_name) { TagName.create!(name: 'spec_wiki_asset_page') }
+  let!(:page) do
+    WikiPage.create!(tag_name: tag_name, created_user: member, updated_user: member).tap do |p|
+      Wiki::Commit.content!(page: p, body: 'init', created_user: member, message: 'init')
+    end
+  end
+
+  describe 'GET /wiki/:wiki_page_id/assets' do
+    subject(:do_request) do
+      get "/wiki/#{wiki_page_id}/assets"
+    end
+
+    let(:wiki_page_id) { page.id }
+
+    let!(:asset) do
+      WikiAsset.new(wiki_page: page,
+                    no: 1,
+                    alt_text: 'spec alt',
+                    sha256: Digest::SHA256.digest('asset-1'),
+                    created_by_user: member).tap do |record|
+        record.file.attach(dummy_upload('asset-1'))
+        record.save!
+      end
+    end
+
+    context 'when wiki page exists' do
+      it 'returns assets for the page' do
+        do_request
+
+        expect(response).to have_http_status(:ok)
+        expect(json).to be_an(Array)
+        expect(json.size).to eq(1)
+
+        expect(json.first).to include(
+            'wiki_page_id' => page.id,
+            'no' => 1)
+      end
+
+      it 'does not include assets from other pages' do
+        other_tag_name = TagName.create!(name: 'spec_other_wiki_asset_page')
+        other_page = WikiPage.create!(tag_name: other_tag_name,
+                                      created_user: member,
+                                      updated_user: member)
+        Wiki::Commit.content!(page: other_page, body: 'other', created_user: member, message: 'other')
+
+        WikiAsset.new(wiki_page: other_page,
+                      no: 1,
+                      alt_text: 'other alt',
+                      sha256: Digest::SHA256.digest('asset-2'),
+                      created_by_user: member).tap do |record|
+          record.file.attach(dummy_upload('asset-2', filename: 'other.png'))
+          record.save!
+        end
+
+        do_request
+
+        expect(response).to have_http_status(:ok)
+        expect(json.size).to eq(1)
+        expect(json.first['wiki_page_id']).to eq(page.id)
+      end
+    end
+
+    context 'when wiki page does not exist' do
+      let(:wiki_page_id) { 999_999_999 }
+
+      it 'returns 404' do
+        do_request
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+  end
+
+  describe 'POST /wiki/:wiki_page_id/assets' do
+    subject(:do_request) do
+      post "/wiki/#{wiki_page_id}/assets", params: params
+    end
+
+    let(:wiki_page_id) { page.id }
+    let(:params) do
+      { file: dummy_upload(upload_content),
+        alt_text: 'uploaded alt' }
+    end
+    let(:upload_content) { 'uploaded-image-binary' }
+
+    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 wiki page does not exist' do
+      let(:wiki_page_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 file is blank' do
+      let(:params) { { alt_text: 'uploaded alt' } }
+
+      it 'returns 400' do
+        sign_in_as(member)
+        do_request
+        expect(response).to have_http_status(:bad_request)
+      end
+    end
+
+    context 'when success' do
+      before do
+        sign_in_as(member)
+      end
+
+      it 'creates asset, attaches file, increments next_asset_no, and returns json' do
+        expect { do_request }
+          .to change(WikiAsset, :count).by(1)
+
+        expect(response).to have_http_status(:ok)
+
+        asset = WikiAsset.order(:id).last
+        expect(asset.wiki_page_id).to eq(page.id)
+        expect(asset.no).to eq(1)
+        expect(asset.alt_text).to eq('uploaded alt')
+        expect(asset.sha256).to eq(Digest::SHA256.digest(upload_content))
+        expect(asset.created_by_user_id).to eq(member.id)
+        expect(asset.file).to be_attached
+        expect(asset.file.download).to eq(upload_content)
+
+        expect(page.reload.next_asset_no).to eq(2)
+
+        expect(json).to include(
+          'wiki_page_id' => page.id,
+          'no' => 1,
+          'url' => asset.url
+        )
+      end
+
+      it 'uses the next page-local number when assets already exist' do
+        existing = WikiAsset.new(wiki_page: page,
+                                 no: 1,
+                                 alt_text: 'existing alt',
+                                 sha256: Digest::SHA256.digest('existing'),
+                                 created_by_user: member)
+        existing.file.attach(dummy_upload('existing', filename: 'existing.png'))
+        existing.save!
+        page.update!(next_asset_no: 2)
+
+        do_request
+
+        expect(response).to have_http_status(:ok)
+
+        asset = WikiAsset.order(:id).last
+        expect(asset.no).to eq(2)
+        expect(page.reload.next_asset_no).to eq(3)
+
+        expect(json).to include(
+          'wiki_page_id' => page.id,
+          'no' => 2,
+          'url' => asset.url
+        )
+      end
+    end
+  end
+end

backend/spec/requests/wiki_spec.rb

@@ -113,6 +113,7 @@ RSpec.describe 'Wiki API', type: :request do
 
         page_id = json.fetch('id')
         expect(json.fetch('title')).to eq('TestPage')
+        expect(json.fetch('body')).to eq("a\nb\nc")
 
         created_page = WikiPage.find(page_id)
         version = created_page.wiki_versions.order(:version_no).last

backend/spec/services/youtube/api_client_spec.rb

@@ -0,0 +1,130 @@
+require 'rails_helper'
+
+RSpec.describe Youtube::ApiClient do
+  let(:api_key) { 'test-api-key' }
+  let(:client) { described_class.new(api_key:) }
+
+  describe '#search_videos' do
+    it 'calls YouTube search API with expected params' do
+      published_after = Time.zone.parse('2026-05-01 00:00:00')
+      published_before = Time.zone.parse('2026-05-02 00:00:00')
+
+      expect(client).to receive(:get_json).with(
+        '/search',
+        {
+          part: 'snippet',
+          type: 'video',
+          q: 'ぼざろクリーチャー',
+          order: 'date',
+          maxResults: 50,
+          regionCode: 'JP',
+          relevanceLanguage: 'ja',
+          publishedAfter: published_after.iso8601,
+          publishedBefore: published_before.iso8601,
+          pageToken: 'NEXT'
+        }
+      ).and_return({ 'items' => [] })
+
+      client.search_videos(
+        q: 'ぼざろクリーチャー',
+        published_after:,
+        published_before:,
+        page_token: 'NEXT'
+      )
+    end
+
+    it 'omits nil optional params' do
+      expect(client).to receive(:get_json).with(
+        '/search',
+        hash_excluding(:publishedAfter, :publishedBefore, :pageToken)
+      ).and_return({ 'items' => [] })
+
+      client.search_videos(q: 'ぼざろクリーチャー')
+    end
+  end
+
+  describe '#videos' do
+    it 'returns empty items when ids are empty' do
+      expect(client).not_to receive(:get_json)
+
+      expect(client.videos([])).to eq({ 'items' => [] })
+    end
+
+    it 'calls videos API with comma separated ids' do
+      expect(client).to receive(:get_json).with(
+        '/videos',
+        {
+          part: 'snippet,status,contentDetails',
+          id: 'video-1,video-2'
+        }
+      ).and_return({ 'items' => [] })
+
+      client.videos(['video-1', 'video-2'])
+    end
+  end
+
+  describe '#playlist_items' do
+    it 'calls playlistItems API with page token' do
+      expect(client).to receive(:get_json).with(
+        '/playlistItems',
+        {
+          part: 'snippet,contentDetails,status',
+          playlistId: 'PL123',
+          maxResults: 50,
+          pageToken: 'NEXT'
+        }
+      ).and_return({ 'items' => [] })
+
+      client.playlist_items(playlist_id: 'PL123', page_token: 'NEXT')
+    end
+
+    it 'omits page token when nil' do
+      expect(client).to receive(:get_json).with(
+        '/playlistItems',
+        {
+          part: 'snippet,contentDetails,status',
+          playlistId: 'PL123',
+          maxResults: 50
+        }
+      ).and_return({ 'items' => [] })
+
+      client.playlist_items(playlist_id: 'PL123')
+    end
+  end
+
+  describe '#channel' do
+    it 'calls channels API by id' do
+      expect(client).to receive(:get_json).with(
+        '/channels',
+        {
+          part: 'snippet,contentDetails',
+          id: 'UC123'
+        }
+      ).and_return({ 'items' => [] })
+
+      client.channel(id: 'UC123')
+    end
+
+    it 'calls channels API by handle' do
+      expect(client).to receive(:get_json).with(
+        '/channels',
+        {
+          part: 'snippet,contentDetails',
+          forHandle: '@some_handle'
+        }
+      ).and_return({ 'items' => [] })
+
+      client.channel(handle: '@some_handle')
+    end
+
+    it 'raises when neither id nor handle is given' do
+      expect { client.channel }.to raise_error(ArgumentError, 'id or handle is required')
+    end
+
+    it 'raises when both id and handle are given' do
+      expect do
+        client.channel(id: 'UC123', handle: '@some_handle')
+      end.to raise_error(ArgumentError, 'id or handle is required')
+    end
+  end
+end

backend/spec/services/youtube/sync_spec.rb

@@ -0,0 +1,310 @@
+require 'rails_helper'
+
+RSpec.describe Youtube::Sync do
+  let(:client) { instance_double(Youtube::ApiClient) }
+  let(:sync) { described_class.new(client:) }
+
+  before do
+    allow(PostVersionRecorder).to receive(:record!)
+    allow(PostVersionRecorder).to receive(:ensure_snapshot!)
+    allow(sync).to receive(:attach_thumbnail_if_needed!)
+  end
+
+  describe '#sync!' do
+    it 'returns without fetching video details when no video ids are discovered' do
+      allow(sync).to receive(:query_terms).and_return([])
+      allow(sync).to receive(:playlist_ids).and_return([])
+
+      expect(client).not_to receive(:videos)
+
+      sync.sync!
+    end
+
+    it 'discovers ids from search and all playlist pages' do
+      allow(sync).to receive(:query_terms).and_return(['ぼざろクリーチャー'])
+      allow(sync).to receive(:playlist_ids).and_return(['PL123'])
+      allow(sync).to receive(:sync_since).and_return(Time.zone.parse('2026-05-01 00:00:00'))
+
+      allow(client).to receive(:search_videos).with(
+        q: 'ぼざろクリーチャー',
+        published_after: Time.zone.parse('2026-05-01 00:00:00')
+      ).and_return({
+        'items' => [
+          {
+            'id' => {
+              'videoId' => 'search-video-1'
+            }
+          }
+        ]
+      })
+
+      allow(client).to receive(:playlist_items).with(
+        playlist_id: 'PL123',
+        page_token: nil
+      ).and_return({
+        'items' => [
+          {
+            'contentDetails' => {
+              'videoId' => 'playlist-video-1'
+            }
+          }
+        ],
+        'nextPageToken' => 'NEXT'
+      })
+
+      allow(client).to receive(:playlist_items).with(
+        playlist_id: 'PL123',
+        page_token: 'NEXT'
+      ).and_return({
+        'items' => [
+          {
+            'snippet' => {
+              'resourceId' => {
+                'videoId' => 'playlist-video-2'
+              }
+            }
+          }
+        ]
+      })
+
+      expect(client).to receive(:videos).with(
+        satisfy do |ids|
+          ids.sort == ['playlist-video-1', 'playlist-video-2', 'search-video-1']
+        end
+      ).and_return({ 'items' => [] })
+
+      sync.sync!
+    end
+
+    it 'creates a YouTube post with default tags and no_deerjikist when no deerjikist mapping exists' do
+      Tag.tagme
+      Tag.bot
+      Tag.youtube
+      Tag.video
+      Tag.no_deerjikist
+
+      allow(sync).to receive(:query_terms).and_return([])
+      allow(sync).to receive(:playlist_ids).and_return(['PL123'])
+
+      allow(client).to receive(:playlist_items).with(
+        playlist_id: 'PL123',
+        page_token: nil
+      ).and_return({
+        'items' => [
+          {
+            'contentDetails' => {
+              'videoId' => 'video-1'
+            }
+          }
+        ]
+      })
+
+      allow(client).to receive(:videos).with(['video-1']).and_return({
+        'items' => [
+          youtube_video_item(
+            id: 'video-1',
+            title: 'YouTube テスト動画',
+            channel_id: 'UC_NO_MAPPING'
+          )
+        ]
+      })
+
+      expect do
+        sync.sync!
+      end.to change(Post, :count).by(1)
+
+      post = Post.find_by!(url: 'https://www.youtube.com/watch?v=video-1')
+      tag_ids = post.tags.pluck(:id)
+
+      expect(post.title).to eq('YouTube テスト動画')
+      expect(post.uploaded_user_id).to be_nil
+      expect(post.original_created_from).to eq(Time.zone.parse('2026-05-01 12:34:00'))
+      expect(post.original_created_before).to eq(Time.zone.parse('2026-05-01 12:35:00'))
+
+      expect(tag_ids).to include(Tag.tagme.id)
+      expect(tag_ids).to include(Tag.bot.id)
+      expect(tag_ids).to include(Tag.youtube.id)
+      expect(tag_ids).to include(Tag.video.id)
+      expect(tag_ids).to include(Tag.no_deerjikist.id)
+
+      expect(PostVersionRecorder).to have_received(:record!).with(
+        post:,
+        event_type: :create,
+        created_by_user: nil
+      )
+    end
+
+    it 'uses deerjikist tag when channel id is mapped' do
+      Tag.tagme
+      Tag.bot
+      Tag.youtube
+      Tag.video
+      Tag.no_deerjikist
+
+      deerjikist_tag = Tag.find_or_create_by_tag_name!('テスト投稿者', category: :deerjikist)
+      Deerjikist.create!(
+        platform: 'youtube',
+        code: 'UC_MAPPED',
+        tag: deerjikist_tag
+      )
+
+      allow(sync).to receive(:query_terms).and_return([])
+      allow(sync).to receive(:playlist_ids).and_return(['PL123'])
+
+      allow(client).to receive(:playlist_items).with(
+        playlist_id: 'PL123',
+        page_token: nil
+      ).and_return({
+        'items' => [
+          {
+            'contentDetails' => {
+              'videoId' => 'video-1'
+            }
+          }
+        ]
+      })
+
+      allow(client).to receive(:videos).with(['video-1']).and_return({
+        'items' => [
+          youtube_video_item(
+            id: 'video-1',
+            title: 'YouTube テスト動画',
+            channel_id: 'UC_MAPPED'
+          )
+        ]
+      })
+
+      sync.sync!
+
+      post = Post.find_by!(url: 'https://www.youtube.com/watch?v=video-1')
+      tag_ids = post.tags.pluck(:id)
+
+      expect(tag_ids).to include(deerjikist_tag.id)
+      expect(tag_ids).not_to include(Tag.no_deerjikist.id)
+    end
+
+    it 'removes no_deerjikist when deerjikist mapping is added later' do
+      Tag.no_deerjikist
+
+      post = Post.create!(
+        title: '旧タイトル',
+        url: 'https://www.youtube.com/watch?v=video-1',
+        uploaded_user_id: nil,
+        original_created_from: Time.zone.parse('2026-05-01 00:00:00'),
+        original_created_before: Time.zone.parse('2026-05-01 00:01:00')
+      )
+      PostTag.create!(post:, tag: Tag.no_deerjikist)
+
+      deerjikist_tag = Tag.find_or_create_by_tag_name!('後から判明した投稿者', category: :deerjikist)
+      Deerjikist.create!(
+        platform: 'youtube',
+        code: 'UC_MAPPED_LATER',
+        tag: deerjikist_tag
+      )
+
+      allow(sync).to receive(:query_terms).and_return([])
+      allow(sync).to receive(:playlist_ids).and_return(['PL123'])
+
+      allow(client).to receive(:playlist_items).with(
+        playlist_id: 'PL123',
+        page_token: nil
+      ).and_return({
+        'items' => [
+          {
+            'contentDetails' => {
+              'videoId' => 'video-1'
+            }
+          }
+        ]
+      })
+
+      allow(client).to receive(:videos).with(['video-1']).and_return({
+        'items' => [
+          youtube_video_item(
+            id: 'video-1',
+            title: '新タイトル',
+            channel_id: 'UC_MAPPED_LATER'
+          )
+        ]
+      })
+
+      sync.sync!
+
+      post.reload
+      tag_ids = post.tags.pluck(:id)
+
+      expect(post.title).to eq('新タイトル')
+      expect(tag_ids).to include(deerjikist_tag.id)
+      expect(tag_ids).not_to include(Tag.no_deerjikist.id)
+
+      expect(PostVersionRecorder).to have_received(:ensure_snapshot!).with(
+        post,
+        created_by_user: nil
+      )
+      expect(PostVersionRecorder).to have_received(:record!).with(
+        post:,
+        event_type: :update,
+        created_by_user: nil
+      )
+    end
+
+    it 'matches existing youtu.be URL and does not create duplicate post' do
+      post = Post.create!(
+        title: '旧タイトル',
+        url: 'https://youtu.be/video-1',
+        uploaded_user_id: nil,
+        original_created_from: Time.zone.parse('2026-05-01 00:00:00'),
+        original_created_before: Time.zone.parse('2026-05-01 00:01:00')
+      )
+
+      allow(sync).to receive(:query_terms).and_return([])
+      allow(sync).to receive(:playlist_ids).and_return(['PL123'])
+
+      allow(client).to receive(:playlist_items).with(
+        playlist_id: 'PL123',
+        page_token: nil
+      ).and_return({
+        'items' => [
+          {
+            'contentDetails' => {
+              'videoId' => 'video-1'
+            }
+          }
+        ]
+      })
+
+      allow(client).to receive(:videos).with(['video-1']).and_return({
+        'items' => [
+          youtube_video_item(
+            id: 'video-1',
+            title: '新タイトル',
+            channel_id: 'UC_NO_MAPPING'
+          )
+        ]
+      })
+
+      expect do
+        sync.sync!
+      end.not_to change(Post, :count)
+
+      expect(post.reload.title).to eq('新タイトル')
+    end
+  end
+
+  def youtube_video_item(id:, title:, channel_id:)
+    {
+      'id' => id,
+      'snippet' => {
+        'title' => title,
+        'channelId' => channel_id,
+        'publishedAt' => '2026-05-01T12:34:56Z',
+        'thumbnails' => {
+          'high' => {
+            'url' => "https://img.youtube.com/#{id}.jpg"
+          }
+        },
+        'tags' => ['tag-a', 'tag-b']
+      }
+    }
+  end
+end

backend/spec/services/youtube/video_item_spec.rb

@@ -0,0 +1,93 @@
+require 'rails_helper'
+
+RSpec.describe Youtube::VideoItem do
+  describe '#initialize' do
+    it 'extracts fields from YouTube video API item' do
+      item = {
+        'id' => 'video-1',
+        'snippet' => {
+          'title' => 'テスト動画',
+          'channelId' => 'UC123',
+          'publishedAt' => '2026-05-01T12:34:56Z',
+          'tags' => ['tag-a', 'tag-b'],
+          'thumbnails' => {
+            'high' => {
+              'url' => 'https://img.youtube.com/high.jpg'
+            },
+            'medium' => {
+              'url' => 'https://img.youtube.com/medium.jpg'
+            }
+          }
+        }
+      }
+
+      video = described_class.new(item)
+
+      expect(video.id).to eq('video-1')
+      expect(video.title).to eq('テスト動画')
+      expect(video.channel_id).to eq('UC123')
+      expect(video.published_at).to eq(Time.iso8601('2026-05-01T12:34:56Z'))
+      expect(video.thumbnail_url).to eq('https://img.youtube.com/high.jpg')
+      expect(video.raw_tags).to eq(['tag-a', 'tag-b'])
+      expect(video.url).to eq('https://www.youtube.com/watch?v=video-1')
+    end
+
+    it 'uses highest priority thumbnail' do
+      item = {
+        'id' => 'video-1',
+        'snippet' => {
+          'title' => 'テスト動画',
+          'channelId' => 'UC123',
+          'publishedAt' => '2026-05-01T12:34:56Z',
+          'thumbnails' => {
+            'default' => {
+              'url' => 'https://img.youtube.com/default.jpg'
+            },
+            'standard' => {
+              'url' => 'https://img.youtube.com/standard.jpg'
+            },
+            'maxres' => {
+              'url' => 'https://img.youtube.com/maxres.jpg'
+            }
+          }
+        }
+      }
+
+      video = described_class.new(item)
+
+      expect(video.thumbnail_url).to eq('https://img.youtube.com/maxres.jpg')
+    end
+
+    it 'falls back to empty raw tags' do
+      item = {
+        'id' => 'video-1',
+        'snippet' => {
+          'title' => 'テスト動画',
+          'channelId' => 'UC123',
+          'publishedAt' => '2026-05-01T12:34:56Z',
+          'thumbnails' => {}
+        }
+      }
+
+      video = described_class.new(item)
+
+      expect(video.raw_tags).to eq([])
+    end
+
+    it 'returns nil thumbnail when no thumbnail exists' do
+      item = {
+        'id' => 'video-1',
+        'snippet' => {
+          'title' => 'テスト動画',
+          'channelId' => 'UC123',
+          'publishedAt' => '2026-05-01T12:34:56Z',
+          'thumbnails' => {}
+        }
+      }
+
+      video = described_class.new(item)
+
+      expect(video.thumbnail_url).to be_nil
+    end
+  end
+end

backend/spec/support/test_records.rb

@@ -3,13 +3,13 @@ module TestRecords
     User.create!(name: 'spec user',
                  inheritance_code: SecureRandom.hex(16),
                  role: 'member',
-                 banned: false)
+                 banned_at: nil)
   end
 
   def create_admin_user!
     User.create!(name: 'spec admin',
                  inheritance_code: SecureRandom.hex(16),
                  role: 'admin',
-                 banned: false)
+                 banned_at: nil)
   end
 end

backend/spec/tasks/nico_sync_spec.rb

@@ -104,7 +104,6 @@ RSpec.describe "nico:sync" do
       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,

backend/spec/tasks/post_sync_spec.rb

@@ -0,0 +1,25 @@
+require 'rails_helper'
+require 'rake'
+
+RSpec.describe 'post:sync' do
+  around do |example|
+    original_application = Rake.application
+    Rake.application = Rake::Application.new
+
+    Rake::Task.define_task(:environment)
+    load Rails.root.join('lib/tasks/sync_posts.rake')
+
+    example.run
+  ensure
+    Rake.application = original_application
+  end
+
+  it 'runs Youtube::Sync' do
+    sync = instance_double(Youtube::Sync)
+
+    expect(Youtube::Sync).to receive(:new).once.and_return(sync)
+    expect(sync).to receive(:sync!).once
+
+    Rake::Task['post:sync'].invoke
+  end
+end

frontend/src/components/WikiBody.tsx

@@ -1,42 +1,9 @@
-import { useQuery } from '@tanstack/react-query'
-import { useMemo } from 'react'
-import ReactMarkdown from 'react-markdown'
-import remarkGFM from 'remark-gfm'
-
-import PrefetchLink from '@/components/PrefetchLink'
-import { wikiKeys } from '@/lib/queryKeys'
-import remarkWikiAutoLink from '@/lib/remark-wiki-autolink'
-import { fetchWikiPages } from '@/lib/wiki'
+import WikiMarkdown from '@/components/WikiMarkdown'
 
 import type { FC } from 'react'
-import type { Components } from 'react-markdown'
 
 type Props = { title: string
 	       body?: string }
 
-const mdComponents = { a: (({ href, children }) => (
-			      ['/', '.'].some (e => href?.startsWith (e))
-			      ? <PrefetchLink to={href!}>{children}</PrefetchLink>
-			      : (
-				  <a href={href}
-				     target="_blank"
-				     rel="noopener noreferrer">
-				    {children}
-				  </a>))) } as const satisfies Components
-
-
-export default (({ title, body }: Props) => {
-  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])
-
-  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) })。`}
-      </ReactMarkdown>)
-}) satisfies FC<Props>
+export default (({ title, body }: Props) =>
+    <WikiMarkdown title={title} body={body ?? ''}/>) satisfies FC<Props>

frontend/src/components/WikiEditForm.tsx

@@ -0,0 +1,76 @@
+import { useEffect, useState } from 'react'
+import MdEditor from 'react-markdown-editor-lite'
+
+import WikiMarkdown from '@/components/WikiMarkdown'
+import Label from '@/components/common/Label'
+import { apiPost } from '@/lib/api'
+
+import type { FC } from 'react'
+
+import type { WikiAsset } from '@/types'
+
+type Props = {
+    title:    string
+    body:     string
+    onSubmit: (title: string, body: string) => void
+    id?:      number | null }
+
+
+export default (({ title: initTitle, body: initBody, onSubmit, id }: Props) => {
+  const forEdit = id != null
+
+  const [title, setTitle] = useState<string> (initTitle)
+  const [body, setBody] = useState<string> (initBody)
+
+  useEffect (() => {
+    setTitle (initTitle)
+    setBody (initBody)
+  }, [initTitle, initBody])
+
+  const handleImageUpload = async (file: File) => {
+    if (!(forEdit))
+      throw new Error ('画像は Wiki 作成前に追加することができません．')
+
+    const formData = new FormData
+    formData.append ('file', file)
+
+    const asset = await apiPost<WikiAsset> (
+	`/wiki/${ id }/assets`,
+	formData,
+	{ headers: { 'Content-Type': 'multipart/form-data' } })
+
+    return asset.url
+  }
+
+  return (
+      <>
+	{/* タイトル */}
+	{/* TODO: タグ補完 */}
+	<div>
+	  <Label>タイトル</Label>
+	  <input
+	      type="text"
+	      value={title}
+	      onChange={e => setTitle (e.target.value)}
+	      className="w-full border p-2 rounded"/>
+	</div>
+
+	{/* 本文 */}
+	<div>
+	  <Label>本文</Label>
+	  <MdEditor
+	      value={body}
+	      style={{ height: '500px' }}
+	      renderHTML={text => <WikiMarkdown body={text} preview/>}
+	      onChange={({ text }) => setBody (text)}
+	      onImageUpload={handleImageUpload}/>
+	</div>
+
+	{/* 送信 */}
+	<button
+	    onClick={() => onSubmit (title, body)}
+	    className="px-4 py-2 bg-blue-600 text-white rounded disabled:bg-gray-400">
+	  {forEdit ? '編輯' : '追加'}
+	</button>
+      </>)
+}) satisfies FC<Props>

frontend/src/components/WikiMarkdown.tsx

@@ -0,0 +1,77 @@
+import { useQuery } from '@tanstack/react-query'
+import { useMemo } from 'react'
+import ReactMarkdown from 'react-markdown'
+import remarkGFM from 'remark-gfm'
+
+import PrefetchLink from '@/components/PrefetchLink'
+import SectionTitle from '@/components/common/SectionTitle'
+import SubsectionTitle from '@/components/common/SubsectionTitle'
+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'
+
+type Props = {
+    title?:   string
+    body:     string
+    preview?: boolean }
+
+
+const makeComponents = (preview = false) => (
+    { 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 }) => {
+	if (!(href))
+	  return <>{children}</>
+
+	if (!(preview) && ['/', '.'].some (e => href.startsWith (e)))
+	  return <PrefetchLink to={href}>{children}</PrefetchLink>
+
+	const ext = /^(?:https?:)?\/\//.test (href)
+
+	return (
+	    <a href={href}
+	       target={ext ? '_blank' : undefined}
+	       rel={ext ? 'noopener noreferrer' : undefined}>
+	      {children}
+	    </a>)
+      },
+      img: (({ src, alt }) => (
+	  <img src={src ?? ''}
+	       alt={alt ?? ''}
+	       className="max-w-[240px] max-h-[320px]"/>)),
+    } as const satisfies Components)
+
+
+export default (({ title, body, preview = false }: Props) => {
+  const { data } = useQuery ({
+      queryKey: wikiKeys.index ({ }),
+      queryFn: () => fetchWikiPages ({ }) })
+
+  const pageNames = useMemo (
+      () => (data ?? []).map ((page) => page.title).sort ((a, b) => b.length - a.length),
+      [data])
+
+  const remarkPlugins = useMemo (
+      () => [() => remarkWikiAutoLink (pageNames), remarkGFM],
+      [pageNames])
+
+  const components = useMemo (
+      () => makeComponents (preview),
+      [preview])
+
+  return (
+      <ReactMarkdown
+	  components={components}
+	  remarkPlugins={remarkPlugins}>
+        {body
+	 || (title
+	     ? ('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) })。`)
+	     : '')}
+      </ReactMarkdown>)
+}) satisfies FC<Props>

frontend/src/pages/wiki/WikiEditPage.tsx

@@ -1,10 +1,9 @@
 import { useQueryClient } from '@tanstack/react-query'
-import MarkdownIt from 'markdown-it'
 import { useEffect, useState } from 'react'
 import { Helmet } from 'react-helmet-async'
-import MdEditor from 'react-markdown-editor-lite'
 import { useParams, useNavigate } from 'react-router-dom'
 
+import WikiEditForm from '@/components/WikiEditForm'
 import MainArea from '@/components/layout/MainArea'
 import { toast } from '@/components/ui/use-toast'
 import { SITE_TITLE } from '@/config'
@@ -18,8 +17,6 @@ import type { FC } from 'react'
 
 import type { User, WikiPage } from '@/types'
 
-const mdParser = new MarkdownIt
-
 type Props = { user: User | null }
 
 
@@ -37,7 +34,7 @@ export default (({ user }: Props) => {
   const [loading, setLoading] = useState (true)
   const [title, setTitle] = useState ('')
 
-  const handleSubmit = async () => {
+  const handleSubmit = async (title: string, body: string) => {
     const formData = new FormData ()
     formData.append ('title', title)
     formData.append ('body', body)
@@ -46,8 +43,6 @@ export default (({ user }: Props) => {
     {
       await apiPut (`/wiki/${ id }`, formData,
 		    { headers: { 'Content-Type': 'multipart/form-data' } })
-      qc.setQueryData (wikiKeys.show (title, { }),
-		       (prev: WikiPage) => ({ ...prev, title, body }))
       qc.invalidateQueries ({ queryKey: wikiKeys.root })
       toast ({ title: '投稿成功!' })
       navigate (`/wiki/${ title }`)
@@ -77,32 +72,11 @@ export default (({ user }: Props) => {
 	  <h1 className="text-2xl font-bold mb-2">Wiki ページを編輯</h1>
 
 	  {loading ? 'Loading...' : (
-	      <>
-		{/* タイトル */}
-		{/* TODO: タグ補完 */}
-		<div>
-		  <label className="block font-semibold mb-1">タイトル</label>
-		  <input type="text"
-			 value={title}
-			 onChange={e => setTitle (e.target.value)}
-			 className="w-full border p-2 rounded"/>
-		</div>
-
-		{/* 本文 */}
-		<div>
-		  <label className="block font-semibold mb-1">本文</label>
-		  <MdEditor value={body}
-			    style={{ height: '500px' }}
-			    renderHTML={text => mdParser.render (text)}
-			    onChange={({ text }) => setBody (text)}/>
-		</div>
-
-		{/* 送信 */}
-		<button onClick={handleSubmit}
-			className="px-4 py-2 bg-blue-600 text-white rounded disabled:bg-gray-400">
-		  編輯
-		</button>
-	      </>)}
+	      <WikiEditForm
+		  title={title}
+		  body={body}
+		  onSubmit={handleSubmit}
+		  id={Number (id)}/>)}
 	</div>
       </MainArea>)
 }) satisfies FC<Props>

frontend/src/pages/wiki/WikiNewPage.tsx

@@ -1,21 +1,19 @@
-import MarkdownIt from 'markdown-it'
-import { useState } from 'react'
+import { useQueryClient } from '@tanstack/react-query'
 import { Helmet } from 'react-helmet-async'
-import MdEditor from 'react-markdown-editor-lite'
 import { useLocation, useNavigate } from 'react-router-dom'
 
+import WikiEditForm from '@/components/WikiEditForm'
 import MainArea from '@/components/layout/MainArea'
 import { toast } from '@/components/ui/use-toast'
 import { SITE_TITLE } from '@/config'
 import { apiPost } from '@/lib/api'
+import { wikiKeys } from '@/lib/queryKeys'
 import Forbidden from '@/pages/Forbidden'
 
 import 'react-markdown-editor-lite/lib/index.css'
 
 import type { User, WikiPage } from '@/types'
 
-const mdParser = new MarkdownIt
-
 type Props = { user: User | null }
 
 
@@ -26,13 +24,12 @@ export default ({ user }: Props) => {
   const location = useLocation ()
   const navigate = useNavigate ()
 
+  const qc = useQueryClient ()
+
   const query = new URLSearchParams (location.search)
   const titleQuery = query.get ('title') ?? ''
 
-  const [title, setTitle] = useState (titleQuery)
-  const [body, setBody] = useState ('')
-
-  const handleSubmit = async () => {
+  const handleSubmit = async (title: string, body: string) => {
     const formData = new FormData
     formData.append ('title', title)
     formData.append ('body', body)
@@ -40,7 +37,8 @@ export default ({ user }: Props) => {
     try
     {
       const data = await apiPost<WikiPage> ('/wiki', formData,
-				  { headers: { 'Content-Type': 'multipart/form-data' } })
+	  { headers: { 'Content-Type': 'multipart/form-data' } })
+      qc.invalidateQueries ({ queryKey: wikiKeys.root })
       toast ({ title: '投稿成功!' })
       navigate (`/wiki/${ data.title }`)
     }
@@ -58,30 +56,10 @@ export default ({ user }: Props) => {
 	<div className="max-w-xl mx-auto p-4 space-y-4">
 	  <h1 className="text-2xl font-bold mb-2">新規 Wiki ページ</h1>
 
-	  {/* タイトル */}
-	  {/* TODO: タグ補完 */}
-	  <div>
-	    <label className="block font-semibold mb-1">タイトル</label>
-	    <input type="text"
-		   value={title}
-		   onChange={e => setTitle (e.target.value)}
-		   className="w-full border p-2 rounded"/>
-	  </div>
-
-	  {/* 本文 */}
-	  <div>
-	    <label className="block font-semibold mb-1">本文</label>
-	    <MdEditor value={body}
-		      style={{ height: '500px' }}
-		      renderHTML={text => mdParser.render (text)}
-		      onChange={({ text }) => setBody (text)}/>
-	  </div>
-
-	  {/* 送信 */}
-	  <button onClick={handleSubmit}
-		  className="px-4 py-2 bg-blue-600 text-white rounded disabled:bg-gray-400">
-	    追加
-	  </button>
+	  <WikiEditForm
+	      title={titleQuery}
+	      body=""
+	      onSubmit={handleSubmit}/>
 	</div>
       </MainArea>)
 }

frontend/src/types.ts

@@ -210,6 +210,11 @@ export type User = {
 
 export type ViewFlagBehavior = typeof ViewFlagBehavior[keyof typeof ViewFlagBehavior]
 
+export type WikiAsset = {
+    wikiPageId: number
+    no:         number
+    url:        string }
+
 export type WikiPage = {
     id:             number
     title:          string