#304

backend/app/controllers/posts_controller.rb

@@ -127,20 +127,17 @@ class PostsController < ApplicationController
     post = Post.new(title:, url:, thumbnail_base: nil, uploaded_user: current_user,
                     original_created_from:, original_created_before:)
     post.thumbnail.attach(thumbnail)
-
-    ActiveRecord::Base.transaction do
-      post.save!
+    if post.save
+      post.resized_thumbnail!
       tags = Tag.normalise_tags(tag_names)
       tags = Tag.expand_parent_tags(tags)
       sync_post_tags!(post, tags)
-      post.resized_thumbnail!
-      PostVersionRecorder.record!(post:, event_type: :create, created_by_user: current_user)
-    end
 
       post.reload
       render json: PostRepr.base(post), status: :created
-  rescue ActiveRecord::RecordInvalid
+    else
       render json: { errors: post.errors.full_messages }, status: :unprocessable_entity
+    end
   rescue Tag::NicoTagNormalisationError
     head :bad_request
   end
@@ -169,22 +166,19 @@ class PostsController < ApplicationController
     original_created_before = params[:original_created_before]
 
     post = Post.find(params[:id].to_i)
-
-    ActiveRecord::Base.transaction do
-      post.update!(title:, original_created_from:, original_created_before:)
+    if post.update(title:, original_created_from:, original_created_before:)
       tags = post.tags.where(category: 'nico').to_a +
              Tag.normalise_tags(tag_names, with_tagme: false)
       tags = Tag.expand_parent_tags(tags)
       sync_post_tags!(post, tags)
-      PostVersionRecorder.record!(post:, event_type: :update, created_by_user: current_user)
-    end
 
       post.reload
       json = post.as_json
       json['tags'] = build_tag_tree_for(post.tags)
       render json:, status: :ok
-  rescue ActiveRecord::RecordInvalid
+    else
       render json: post.errors, status: :unprocessable_entity
+    end
   rescue Tag::NicoTagNormalisationError
     head :bad_request
   end

backend/app/models/post.rb

@@ -11,7 +11,6 @@ class Post < ApplicationRecord
 
   has_many :user_post_views, dependent: :delete_all
   has_many :post_similarities, dependent: :delete_all
-  has_many :post_versions
 
   has_one_attached :thumbnail
 
@@ -31,8 +30,6 @@ class Post < ApplicationRecord
     super(options).merge(thumbnail: nil)
   end
 
-  def snapshot_tag_names = tags.joins(:tag_name).order('tag_names.name').pluck('tag_names.name')
-
   def related limit: nil
     ids = post_similarities.order(cos: :desc)
     ids = ids.limit(limit) if limit

backend/app/models/post_version.rb

@@ -1,38 +0,0 @@
-class PostVersion < ApplicationRecord
-  before_update do
-    raise ActiveRecord::ReadOnlyRecord, '版は更新できません．'
-  end
-
-  before_destroy do
-    raise ActiveRecord::ReadOnlyRecord, '版は削除できません．'
-  end
-
-  belongs_to :post
-  belongs_to :parent, class_name: 'Post', optional: true
-  belongs_to :created_by_user, class_name: 'User', optional: true
-
-  enum :event_type, { create: 'create',
-                      update: 'update',
-                      discard: 'discard',
-                      restore: 'restore' }, prefix: true, validate: true
-
-  validates :version_no, presence: true, numericality: { only_integer: true, greater_than: 0 }
-  validates :event_type, presence: true, inclusion: { in: event_types.keys }
-  validates :url, presence: true
-
-  validate :validate_original_created_range
-
-  scope :chronological, -> { order(:version_no, :id) }
-
-  private
-
-  def validate_original_created_range
-    f = original_created_from
-    b = original_created_before
-    return if f.blank? || b.blank?
-
-    if f >= b
-      errors.add :original_created_before, 'オリジナルの作成日時の順番がをかしぃです．'
-    end
-  end
-end

backend/app/models/tag.rb

@@ -1,6 +1,3 @@
-require 'set'
-
-
 class Tag < ApplicationRecord
   include MyDiscard
 
@@ -153,8 +150,6 @@ class Tag < ApplicationRecord
   def self.merge_tags! target_tag, source_tags
     target_tag => Tag
 
-    affected_post_ids = Set.new
-
     Tag.transaction do
       Array(source_tags).compact.uniq.each do |source_tag|
         source_tag => Tag
@@ -163,7 +158,6 @@ class Tag < ApplicationRecord
 
         source_tag.post_tags.kept.find_each do |source_pt|
           post_id = source_pt.post_id
-          affected_post_ids << post_id
           source_pt.discard_by!(nil)
           unless PostTag.kept.exists?(post_id:, tag: target_tag)
             PostTag.create!(post_id:, tag: target_tag)
@@ -186,10 +180,6 @@ class Tag < ApplicationRecord
         end
       end
 
-      Post.where(id: affected_post_ids.to_a).find_each do |post|
-        PostVersionRecorder.record!(post:, event_type: :update, created_by_user: nil)
-      end
-
       # 投稿件数を再集計
       target_tag.update_columns(post_count: PostTag.kept.where(tag: target_tag).count)
     end

backend/app/services/post_version_recorder.rb

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

backend/db/migrate/20260409123700_create_post_versions.rb

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

backend/db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2026_04_09_123700) do
+ActiveRecord::Schema[8.0].define(version: 2026_03_29_034700) 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
@@ -132,27 +132,6 @@ ActiveRecord::Schema[8.0].define(version: 2026_04_09_123700) do
     t.index ["tag_id"], name: "index_post_tags_on_tag_id"
   end
 
-  create_table "post_versions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.bigint "post_id", null: false
-    t.integer "version_no", null: false
-    t.string "event_type", null: false
-    t.string "title"
-    t.string "url", limit: 768, null: false
-    t.string "thumbnail_base", limit: 2000
-    t.text "tags", null: false
-    t.bigint "parent_id"
-    t.datetime "original_created_from"
-    t.datetime "original_created_before"
-    t.datetime "created_at", null: false
-    t.bigint "created_by_user_id"
-    t.index ["created_by_user_id"], name: "index_post_versions_on_created_by_user_id"
-    t.index ["parent_id"], name: "index_post_versions_on_parent_id"
-    t.index ["post_id", "version_no"], name: "index_post_versions_on_post_id_and_version_no", unique: true
-    t.index ["post_id"], name: "index_post_versions_on_post_id"
-    t.check_constraint "`event_type` in (_utf8mb4'create',_utf8mb4'update',_utf8mb4'discard',_utf8mb4'restore')", name: "post_versions_event_type_valid"
-    t.check_constraint "`version_no` > 0", name: "post_versions_version_no_positive"
-  end
-
   create_table "posts", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "title"
     t.string "url", limit: 768, null: false
@@ -383,9 +362,6 @@ ActiveRecord::Schema[8.0].define(version: 2026_04_09_123700) do
   add_foreign_key "post_tags", "tags"
   add_foreign_key "post_tags", "users", column: "created_user_id"
   add_foreign_key "post_tags", "users", column: "deleted_user_id"
-  add_foreign_key "post_versions", "posts"
-  add_foreign_key "post_versions", "posts", column: "parent_id"
-  add_foreign_key "post_versions", "users", column: "created_by_user_id"
   add_foreign_key "posts", "posts", column: "parent_id"
   add_foreign_key "posts", "users", column: "uploaded_user_id"
   add_foreign_key "settings", "users"

backend/lib/tasks/sync_nico.rake

@@ -61,9 +61,6 @@ namespace :nico do
       original_created_from = original_created_at&.change(sec: 0)
       original_created_before = original_created_from&.+(1.minute)
 
-      post_created = false
-      post_changed = false
-
       if post
         attrs = { title:, original_created_from:, original_created_before: }
 
@@ -79,13 +76,11 @@ namespace :nico do
         end
 
         post.assign_attributes(attrs)
-        post_changed = post.changed?
-        if post_changed
+        if post.changed?
           post.save!
           post.resized_thumbnail! if post.thumbnail.attached?
         end
       else
-        post_created = true
         url = "https://www.nicovideo.jp/watch/#{ code }"
         thumbnail_base = fetch_thumbnail.(url) rescue nil
         post = Post.new(title:, url:, thumbnail_base:, uploaded_user: nil,
@@ -145,12 +140,6 @@ namespace :nico do
       desired_all_tag_ids.uniq!
 
       sync_post_tags!(post, desired_all_tag_ids, current_tag_ids: kept_tag_ids)
-
-      if post_created
-        PostVersionRecorder.record!(post:, event_type: :create, created_by_user: nil)
-      elsif post_changed || kept_tag_ids != desired_all_tag_ids.to_set
-        PostVersionRecorder.record!(post:, event_type: :update, created_by_user: nil)
-      end
     end
   end
 end

backend/spec/models/post_version_spec.rb

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

backend/spec/models/tag_spec.rb

@@ -145,70 +145,5 @@ RSpec.describe Tag, type: :model do
         expect(target_tag.reload.post_count).to eq(0)
       end
     end
-
-    def snapshot_tags(post)
-      post.snapshot_tag_names.join(' ')
-    end
-
-    def create_post_version_for!(post, version_no: 1, event_type: 'create', created_by_user: nil)
-      PostVersion.create!(
-        post: post,
-        version_no: version_no,
-        event_type: event_type,
-        title: post.title,
-        url: post.url,
-        thumbnail_base: post.thumbnail_base,
-        tags: snapshot_tags(post),
-        parent: post.parent,
-        original_created_from: post.original_created_from,
-        original_created_before: post.original_created_before,
-        created_at: Time.current,
-        created_by_user: created_by_user
-      )
-    end
-
-    context 'when post versions are enabled' do
-      let!(:source_post_tag) { PostTag.create!(post: post_record, tag: source_tag) }
-      let!(:unaffected_post) do
-        Post.create!(url: 'https://example.com/posts/2', title: 'unaffected post')
-      end
-
-      before do
-        create_post_version_for!(post_record)
-        create_post_version_for!(unaffected_post)
-      end
-
-      it 'creates an update post_version only for affected posts' do
-        expect {
-          described_class.merge_tags!(target_tag, [source_tag])
-        }.to change(PostVersion, :count).by(1)
-
-        affected_versions = post_record.reload.post_versions.order(:version_no)
-        expect(affected_versions.pluck(:version_no)).to eq([1, 2])
-
-        latest = affected_versions.last
-        expect(latest.event_type).to eq('update')
-        expect(latest.created_by_user).to be_nil
-        expect(latest.tags).to eq(snapshot_tags(post_record.reload))
-
-        expect(unaffected_post.reload.post_versions.count).to eq(1)
-      end
-    end
-
-    context 'when the source tag has no active post_tags' do
-      let!(:another_post) do
-        Post.create!(url: 'https://example.com/posts/3', title: 'another post')
-      end
-
-      before do
-        create_post_version_for!(another_post)
-      end
-
-      it 'does not create any post_version' do
-        expect {
-          described_class.merge_tags!(target_tag, [source_tag])
-        }.not_to change(PostVersion, :count)
-      end
-    end
   end
 end

backend/spec/requests/posts_spec.rb

@@ -795,127 +795,4 @@ RSpec.describe 'Posts API', type: :request do
       expect(user.reload.viewed?(post_record)).to be(false)
     end
   end
-
-  describe 'post versioning' do
-    let(:member) { create(:user, :member) }
-
-    def snapshot_tags(post)
-      post.snapshot_tag_names.join(' ')
-    end
-
-    def create_post_version_for!(post)
-      PostVersion.create!(
-        post: post,
-        version_no: 1,
-        event_type: 'create',
-        title: post.title,
-        url: post.url,
-        thumbnail_base: post.thumbnail_base,
-        tags: snapshot_tags(post),
-        parent: post.parent,
-        original_created_from: post.original_created_from,
-        original_created_before: post.original_created_before,
-        created_at: post.created_at,
-        created_by_user: post.uploaded_user
-      )
-    end
-
-    it 'creates version 1 on POST /posts' do
-      sign_in_as(member)
-
-      expect do
-        post '/posts', params: {
-          title: 'versioned post',
-          url: 'https://example.com/versioned-post',
-          tags: 'spec_tag',
-          thumbnail: dummy_upload
-        }
-      end.to change(PostVersion, :count).by(1)
-
-      expect(response).to have_http_status(:created)
-
-      created_post = Post.find(json.fetch('id'))
-      version = PostVersion.find_by!(post: created_post, version_no: 1)
-
-      expect(version.event_type).to eq('create')
-      expect(version.title).to eq('versioned post')
-      expect(version.url).to eq('https://example.com/versioned-post')
-      expect(version.created_by_user_id).to eq(member.id)
-      expect(version.tags).to eq(snapshot_tags(created_post))
-    end
-
-    it 'creates next version on PUT /posts/:id when snapshot changes' do
-      sign_in_as(member)
-      create_post_version_for!(post_record)
-
-      tag_name2 = TagName.create!(name: 'spec_tag_2')
-      Tag.create!(tag_name: tag_name2, category: :general)
-
-      expect do
-        put "/posts/#{post_record.id}", params: {
-          title: 'updated title',
-          tags: 'spec_tag_2'
-        }
-      end.to change(PostVersion, :count).by(1)
-
-      expect(response).to have_http_status(:ok)
-
-      version = post_record.reload.post_versions.order(:version_no).last
-      expect(version.version_no).to eq(2)
-      expect(version.event_type).to eq('update')
-      expect(version.title).to eq('updated title')
-      expect(version.created_by_user_id).to eq(member.id)
-      expect(version.tags).to eq(snapshot_tags(post_record.reload))
-    end
-
-    it 'does not create a new version on PUT /posts/:id when snapshot is unchanged' do
-      sign_in_as(member)
-      create_post_version_for!(post_record)
-
-      expect do
-        put "/posts/#{post_record.id}", params: {
-          title: post_record.title,
-          tags: 'spec_tag'
-        }
-      end.not_to change(PostVersion, :count)
-
-      expect(response).to have_http_status(:ok)
-
-      version = post_record.reload.post_versions.order(:version_no).last
-      expect(version.version_no).to eq(1)
-      expect(version.event_type).to eq('create')
-      expect(version.tags).to eq(snapshot_tags(post_record))
-    end
-
-    it 'does not create a version when POST /posts is invalid' do
-      sign_in_as(member)
-
-      expect do
-        post '/posts', params: {
-          title: 'invalid post',
-          url: 'ぼざクリタグ広場',
-          tags: 'spec_tag',
-          thumbnail: dummy_upload
-        }
-      end.not_to change(PostVersion, :count)
-
-      expect(response).to have_http_status(:unprocessable_entity)
-    end
-
-    it 'does not create a version when PUT /posts/:id is invalid' do
-      sign_in_as(member)
-      create_post_version_for!(post_record)
-
-      expect do
-        put "/posts/#{post_record.id}", params: {
-          title: 'updated title',
-          tags: 'spec_tag',
-          original_created_from: Time.zone.local(2020, 1, 2, 0, 0, 0).iso8601,
-          original_created_before: Time.zone.local(2020, 1, 1, 0, 0, 0).iso8601
-        }
-      end.not_to change(PostVersion, :count)
-
-      expect(response).to have_http_status(:unprocessable_entity)
-    end
-  end
 end

backend/spec/tasks/nico_sync_spec.rb

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