#399

AGENTS.md

@@ -114,6 +114,9 @@ npm run preview
 - Ruby: `render` 系メソッド呼び出しでは、keyword 引数付きでも括弧を書かない。
 - Ruby: never put a line break immediately before `)`.
 - Ruby: do not use `%w` or `%i`.
+- Ruby: TypeScript / TSX の associative syntax に近い感覚で読むこと。
+  Hash の `}` は block の `}` ではない。call の `)` も function 定義の
+  parameter-list `)` ではない。delimiter の役割を見誤らないこと。
 - In Ruby, when an `if` condition is split across multiple lines and combines
   clauses with `&&` or `||`, wrap the whole condition in parentheses.
 - Ruby hashes are not blocks; keep `}` on the same line as the final pair.
@@ -127,6 +130,152 @@ npm run preview
 - Keep the first element on the same line as `[` by default.
 - If an array would exceed the line limit, break after `[` and indent
   elements by 4 spaces.
+
+### Ruby delimiter and wrapping rules
+
+- Ruby でも、closing delimiter は glyph ではなく syntax role で判定する。
+  `}` が block close なのか hash close なのか、`)` が method call なのか
+  grouping なのかを区別してから配置すること。
+- Ruby の multi-line method call では、receiver / method と opening `(` を
+  同じ行に保ち、closing `)` を単独行へ落とさない。
+- Ruby の multi-line hash literal / keyword-like argument hash では、opening
+  `{` を最初の pair と同じ行に置き、closing `}` を最後の pair と同じ行に
+  置く。Prettier 的な縦開き・縦閉じをしない。
+- Ruby の `if` / `unless` / `case` 条件で、複数行に分けるだけで安易に
+  `if ... end` へ展開しない。局所の既存コードが modifier 形式ならそれに
+  そろえる。
+- Ruby の guard 条件は、1 行で収まるなら modifier 形式を優先する。2 行以上に
+  なるなら通常の block 形式へ切り替へてよい。
+- Ruby の method chain や call argument を折り返す際、call-site の `)`
+  直前で行を空けたり、closing delimiter を block のやうに独立させない。
+
+Bad:
+
+```rb
+source =
+  if params[:format] == 'google_sheets'
+    PostImportGoogleSheetsFetcher.fetch!(params[:source],
+                                         rate_key: current_user.id)
+  else
+    params[:source]
+  end
+parsed = PostImportSourceParser.new(
+  source:,
+  format:,
+  has_header: params[:has_header],
+  json_path: params[:json_path],
+).parse
+```
+
+Good:
+
+```rb
+source =
+    if params[:format] == 'google_sheets'
+      PostImportGoogleSheetsFetcher.fetch!(params[:source],
+                                           rate_key: current_user.id)
+    else
+      params[:source]
+    end
+parsed = PostImportSourceParser.new(
+    source:,
+    format:,
+    has_header: params[:has_header],
+    json_path: params[:json_path]).parse
+```
+
+Bad:
+
+```rb
+result[field] = {
+  'kind' => kind,
+  'value' => value['value'].to_s,
+  'columns' => Array(columns).map { Integer(_1) },
+}
+```
+
+Good:
+
+```rb
+result[field] = {
+    'kind' => kind,
+    'value' => value['value'].to_s,
+    'columns' => Array(columns).map { Integer(_1) } }
+```
+
+Bad:
+
+```rb
+unless rows.all? { |row|
+         values = Array(row['values'])
+         values.length <= columns.length &&
+           values.all? { |value|
+             value.is_a?(String) &&
+               value.bytesize <= PostImportSourceParser::MAX_CELL_BYTES
+           }
+       }
+  raise ArgumentError, '解析結果のセルが不正です．'
+end
+```
+
+Good:
+
+```rb
+raise ArgumentError, '解析結果のセルが不正です．' unless rows.all? { |row|
+  values = Array(row['values'])
+  values.length <= columns.length && values.all? { |value|
+    value.is_a?(String) && value.bytesize <= PostImportSourceParser::MAX_CELL_BYTES
+  }
+}
+```
+
+Bad:
+
+```rb
+if row['url'].to_s.bytesize > PostImportSourceParser::MAX_CELL_BYTES
+  raise ArgumentError, 'URL が長すぎます．'
+end
+```
+
+Good:
+
+```rb
+raise ArgumentError, 'URL が長すぎます．' if row['url'].to_s.bytesize > PostImportSourceParser::MAX_CELL_BYTES
+```
+
+Bad:
+
+```rb
+parameters = row.is_a?(ActionController::Parameters) ? row :
+  ActionController::Parameters.new(row)
+```
+
+Good:
+
+```rb
+parameters =
+    row.is_a?(ActionController::Parameters) ? row : ActionController::Parameters.new(row)
+```
+
+Bad:
+
+```rb
+PostTagSection.create!(
+  post_id: post.id,
+  tag_id:,
+  begin_ms:,
+  end_ms:,
+)
+```
+
+Good:
+
+```rb
+PostTagSection.create!(post_id: post.id,
+                       tag_id:,
+                       begin_ms:,
+                       end_ms:)
+```
 - TypeScript and Python: use GNU-style spacing before parentheses where
   syntactically valid.
 - Never write Ruby, TypeScript, or TSX lines longer than 99 characters.

backend/app/controllers/post_imports_controller.rb

@@ -0,0 +1,45 @@
+class PostImportsController < ApplicationController
+  before_action :require_member!
+
+  def preview
+    rows = PostImportPreviewer.new(existing: params[:existing]).preview_rows(
+        rows: PostImportUrlListParser.parse(params[:source]))
+    render json: { rows: }
+  rescue ArgumentError => e
+    render_bad_request(e.message)
+  end
+
+  def validate
+    rows = normalised_import_rows(allow_warning_fields: true)
+    changed_row = Integer(params[:changed_row], exception: false)
+    result =
+        PostImportPreviewer.new(existing: params[:existing])
+          .preview_rows(rows:, fetch_metadata: changed_row, metadata_cache: {})
+    render json: { rows: result }
+  rescue ArgumentError => e
+    render_bad_request(e.message)
+  end
+
+  def create
+    result = PostImportRunner.new(
+        actor: current_user,
+        rows: normalised_import_rows,
+        existing: params[:existing]).run
+    render json: result, status: result[:created].positive? ? :created : :ok
+  rescue ArgumentError => e
+    render_bad_request(e.message)
+  end
+
+  private
+
+  def require_member!
+    return head :unauthorized unless current_user
+    return if current_user.gte_member?
+
+    head :forbidden
+  end
+
+  def normalised_import_rows allow_warning_fields: false
+    PostImportRowNormaliser.normalise!(params[:rows], allow_warning_fields:)
+  end
+end

backend/app/controllers/posts_controller.rb

@@ -142,37 +142,13 @@ class PostsController < ApplicationController
     return head :unauthorized unless current_user
     return head :forbidden unless current_user.gte_member?
 
-    # TODO: サイトに応じて thumbnail_base 設定
+    post = PostCreator.new(actor: current_user,
-    title = params[:title].presence
+                           attributes: { title: params[:title], url: params[:url],
-    url = params[:url]
+                                         thumbnail: params[:thumbnail], tags: params[:tags],
-    thumbnail = params[:thumbnail]
+                                         original_created_from: params[:original_created_from],
-    tag_names = params[:tags].to_s.split
+                                         original_created_before: params[:original_created_before],
-    original_created_from = params[:original_created_from]
+                                         parent_post_ids: parse_parent_post_ids,
-    original_created_before = params[:original_created_before]
+                                         video_ms: params[:video_ms], duration: params[:duration] }).create!
-    parent_post_ids = parse_parent_post_ids
-    resized_thumbnail = thumbnail.present? ? Post.resized_thumbnail_attachment(thumbnail) : nil
-
-    post = Post.new(title:, url:, thumbnail_base: nil, uploaded_user: current_user,
-                    original_created_from:, original_created_before:)
-    post.thumbnail.attach(resized_thumbnail) if resized_thumbnail
-
-    ApplicationRecord.transaction do
-      post.save!
-
-      Tag.normalise_tags!(tag_names, deny_deprecated: true, with_sections: true) =>
-          { tags:, sections: }
-      TagVersioning.record_tag_snapshots!(tags, created_by_user: current_user)
-
-      tags = Tag.expand_parent_tags(tags).reject(&:deprecated?)
-      post.video_ms = normalise_video_ms(tags)
-      validate_video_sections!(post.video_ms, sections)
-      post.save!
-      sync_post_tags!(post, tags, sections)
-
-      sync_parent_posts!(post, parent_post_ids)
-
-      PostVersionRecorder.record!(post:, event_type: :create, created_by_user: current_user)
-    end
 
     post.reload
     render json: PostRepr.base(post), status: :created
@@ -182,7 +158,7 @@ class PostsController < ApplicationController
     render_unprocessable_entity '廃止済みタグは付与できません．', field: :tags
   rescue Tag::SectionLiteralParseError
     render_validation_error fields: { tags: ['タグ区間の記法が不正です．'] }
-  rescue VideoMsParseError
+  rescue PostCreator::VideoMsParseError
     render_validation_error fields: { video_ms: ['動画時間の記法が不正です．'] }
   rescue MiniMagick::Error
     render_validation_error fields: { thumbnail: ['サムネイル画像の変換に失敗しました．'] }

backend/app/models/post.rb

@@ -173,15 +173,6 @@ class Post < ApplicationRecord
   def normalise_url
     return if url.blank?
 
-    self.url = url.strip
+    self.url = PostUrlNormaliser.normalise(url) || url.strip
-
-    u = URI.parse(url)
-    return unless u in URI::HTTP
-
-    u.host = u.host.downcase if u.host
-    u.path = u.path.sub(/\/\Z/, '') if u.path.present?
-    self.url = u.to_s
-  rescue URI::InvalidURIError
-    ;
   end
 end

backend/app/services/post_creator.rb

@@ -0,0 +1,118 @@
+class PostCreator
+  class VideoMsParseError < ArgumentError; end
+
+  def initialize actor:, attributes:
+    @actor = actor
+    @attributes = attributes.symbolize_keys
+  end
+
+  def create!
+    post = Post.new(title: @attributes[:title].presence,
+                    url: @attributes[:url],
+                    thumbnail_base: @attributes[:thumbnail_base].presence,
+                    uploaded_user: @actor,
+                    original_created_from: @attributes[:original_created_from].presence,
+                    original_created_before: @attributes[:original_created_before].presence)
+    thumbnail = @attributes[:thumbnail]
+    post.thumbnail.attach(Post.resized_thumbnail_attachment(thumbnail)) if thumbnail.present?
+
+    ApplicationRecord.transaction do
+      post.save!
+      Tag.normalise_tags!(tag_names, deny_deprecated: true, with_sections: true) =>
+          { tags:, sections: }
+      TagVersioning.record_tag_snapshots!(tags, created_by_user: @actor)
+      tags = Tag.expand_parent_tags(tags).reject(&:deprecated?)
+      post.video_ms = normalise_video_ms(tags)
+      validate_video_sections!(post.video_ms, sections)
+      post.save!
+      sync_post_tags!(post, tags, sections)
+      sync_parent_posts!(post, parent_post_ids)
+      PostVersionRecorder.record!(post:, event_type: :create, created_by_user: @actor)
+    end
+    post
+  end
+
+  private
+
+  def tag_names = @attributes[:tags].to_s.split
+
+  def parent_post_ids
+    Array(@attributes[:parent_post_ids]).flat_map { _1.to_s.split }.map { |token|
+      id = Integer(token, exception: false)
+      raise ArgumentError, "親投稿 Id. が不正です: #{ token }" if id.nil? || id <= 0
+
+      id
+    }.uniq
+  end
+
+  def normalise_video_ms tags
+    return nil unless tags.any? { _1.id == Tag.video.id }
+
+    video_ms = @attributes[:video_ms]
+    if video_ms.present?
+      value = Integer(video_ms, exception: false)
+      raise VideoMsParseError unless value&.positive?
+
+      return value
+    end
+    duration = @attributes[:duration]
+    return nil if duration.blank?
+
+    return duration.to_i if duration.is_a?(Numeric) && duration.to_i.positive?
+
+    value = Tag.time_to_ms!(duration.to_s, tag_name: '動画時間')
+    raise VideoMsParseError unless value.positive?
+
+    value
+  rescue Tag::SectionLiteralParseError
+    raise VideoMsParseError
+  end
+
+  def validate_video_sections! video_ms, sections
+    return unless video_ms
+
+    sections.each_value do |ranges|
+      ranges.each do |begin_ms, end_ms|
+        next if begin_ms < video_ms && (!end_ms || end_ms <= video_ms)
+
+        post = Post.new
+        post.errors.add :video_ms, 'タグ区間が動画時間の範囲外です．'
+        raise ActiveRecord::RecordInvalid, post
+      end
+    end
+  end
+
+  def sync_post_tags! post, desired_tags, sections
+    desired_ids = desired_tags.map(&:id).to_set
+    current_ids = post.tags.pluck(:id).to_set
+    Tag.where(id: desired_ids - current_ids).find_each do |tag|
+      PostTag.create_or_find_by!(post:, tag:, created_user: @actor)
+    end
+    PostTagSection.where(post_id: post.id).destroy_all
+    sections.each do |tag_id, ranges|
+      ranges.each do |begin_ms, end_ms|
+        PostTagSection.create!(post_id: post.id,
+                               tag_id:,
+                               begin_ms:,
+                               end_ms:)
+      end
+    end
+    PostTag.where(post_id: post.id,
+                  tag_id: (current_ids - desired_ids).to_a).kept.find_each do |post_tag|
+      post_tag.discard_by!(@actor)
+    end
+  end
+
+  def sync_parent_posts! post, ids
+    if ids.include?(post.id)
+      post.errors.add :parent_post_ids, '自分自身を親投稿にはできません．'
+      raise ActiveRecord::RecordInvalid, post
+    end
+    missing = ids - Post.where(id: ids).pluck(:id)
+    if missing.present?
+      post.errors.add :parent_post_ids, "存在しない親投稿 Id. があります: #{ missing.join(' ') }"
+      raise ActiveRecord::RecordInvalid, post
+    end
+    ids.each { |parent_post_id| PostImplication.create_or_find_by!(post:, parent_post_id:) }
+  end
+end

backend/app/services/post_import_previewer.rb

@@ -0,0 +1,226 @@
+class PostImportPreviewer
+  FIELDS = [
+    'title',
+    'thumbnail_base',
+    'original_created_from',
+    'original_created_before',
+    'duration',
+    'tags',
+    'parent_post_ids',
+  ].freeze
+  def initialize existing: 'skip'
+    @existing = existing == 'error' ? 'error' : 'skip'
+  end
+
+  def preview_rows rows:, fetch_metadata: true, metadata_cache: { }
+    urls = {}
+    rows.map { |row|
+      preview_row(row, urls:, fetch_metadata:, metadata_cache:)
+    }
+  end
+
+  def normalised_url value
+    PostUrlNormaliser.normalise(value)
+  end
+
+  private
+
+  def preview_row row, urls:, fetch_metadata:, metadata_cache:
+    row = row.symbolize_keys
+    attributes = initial_attributes(row)
+    provenance = initial_provenance(row)
+    tag_sources = initial_tag_sources(row, attributes, provenance)
+    url = row[:url].to_s.strip
+    provenance['url'] = 'manual'
+    normal_url = normalised_url(url)
+    url_for_metadata = normal_url || url
+    existing_post = normal_url.present? && Post.exists?(url: normal_url)
+
+    validation_warnings = []
+    validation_errors = {}
+    validation_errors[:url] = ['URL が不正です．'] if normal_url.blank?
+    validation_errors[:url] = ['URL が重複しています．'] if normal_url.present? && urls.key?(normal_url)
+    urls[normal_url] = true if normal_url.present?
+    if normal_url.present? && existing_post
+      if @existing == 'error'
+        validation_errors[:url] = ['既存投稿です．']
+      else
+        validation_warnings << '既存投稿のためスキップします．'
+      end
+    end
+
+    if row[:metadata_url].present? && row[:metadata_url] != url_for_metadata
+      clear_automatic_values!(attributes, provenance, tag_sources)
+    end
+
+    fetch_warnings = Array(row[:fetch_warnings]).dup
+    should_fetch = should_fetch_metadata?(fetch_metadata, row[:source_row].to_i)
+    if should_fetch && !(existing_post && @existing == 'skip')
+      metadata, fetch_warnings =
+        metadata_for(url_for_metadata, metadata_cache, fetch_warnings)
+      apply_metadata!(attributes, provenance, tag_sources, metadata)
+    end
+
+    attributes['url'] = url
+    validate_basic_data(attributes, validation_errors)
+    validate_preview_tags(
+      merged_tags(tag_sources, provenance['tags']),
+      validation_errors,
+      validation_warnings,
+    )
+    validate_parents(attributes['parent_post_ids'], validation_errors)
+    attributes.delete('url')
+    attributes['tags'] = merged_tags(tag_sources, provenance['tags'])
+
+    {
+      source_row: row[:source_row],
+      url: normal_url || url,
+      attributes:,
+      provenance:,
+      tag_sources:,
+      metadata_url: url_for_metadata,
+      fetch_warnings:,
+      validation_warnings:,
+      warnings: fetch_warnings + validation_warnings,
+      validation_errors:,
+      status: validation_errors.present? \
+                ? 'error' \
+                : ((fetch_warnings + validation_warnings).present? ? 'warning' : 'ready'),
+      existing: existing_post,
+    }
+  end
+
+  def should_fetch_metadata? fetch_metadata, source_row
+    case fetch_metadata
+    when true then true
+    when Integer then fetch_metadata == source_row
+    when false, nil then false
+    else raise ArgumentError, 'メタデータ取得対象が不正です．'
+    end
+  end
+
+  def initial_attributes row
+    attributes = row[:attributes]&.stringify_keys || {}
+    FIELDS.to_h { |field| [field, attributes[field].to_s] }
+  end
+
+  def initial_provenance row
+    provenance = row[:provenance]&.stringify_keys || {}
+    FIELDS.to_h { |field| [field, provenance[field].presence || 'automatic'] }
+      .merge('url' => 'manual')
+  end
+
+  def initial_tag_sources row, attributes, provenance
+    sources = row[:tag_sources]&.stringify_keys || { 'automatic' => '', 'manual' => '' }
+    sources['automatic'] = sources['automatic'].to_s
+    sources['manual'] =
+      provenance['tags'] == 'manual' ? attributes['tags'].to_s : sources['manual'].to_s
+    sources
+  end
+
+  def clear_automatic_values! attributes, provenance, tag_sources
+    ['title', 'thumbnail_base', 'original_created_from',
+     'original_created_before', 'duration'].each do |field|
+      attributes[field] = '' if provenance[field] == 'automatic'
+    end
+    tag_sources['automatic'] = ''
+    attributes['tags'] = merged_tags(tag_sources, provenance['tags'])
+  end
+
+  def metadata_for url, cache, previous_warnings
+    cache[url] ||= fetch_metadata(url)
+  end
+
+  def fetch_metadata url
+    return [{}, ['URL が空です．']] if url.blank?
+
+    data = PostMetadataFetcher.fetch(url).stringify_keys
+    warnings = []
+    warnings << 'タイトルを取得できませんでした．' if data['title'].blank?
+    warnings << 'サムネールを取得できませんでした．' if data['thumbnail_base'].blank?
+    [data.compact, warnings]
+  rescue Preview::UrlSafety::UnsafeUrl,
+         Preview::HttpFetcher::FetchFailed,
+         Preview::HttpFetcher::ResponseTooLarge => e
+    Rails.logger.info(
+      "post_import_metadata_fetch_failure "\
+      "#{ { error: e.class.name, message: e.message }.to_json }",
+    )
+    [{}, ['メタデータを取得できませんでした．']]
+  end
+
+  def apply_metadata! attributes, provenance, tag_sources, metadata
+    metadata.each do |field, value|
+      if field == 'tags'
+        next if provenance['tags'] == 'manual'
+
+        tag_sources['automatic'] = value.to_s
+        attributes['tags'] = merged_tags(tag_sources)
+        next
+      end
+      next unless provenance[field] == 'automatic' || attributes[field].blank?
+
+      attributes[field] = value
+      provenance[field] = 'automatic'
+    end
+  end
+
+  def merged_tags sources, origin = nil
+    return sources['manual'].to_s if origin == 'manual'
+
+    sources['automatic'].to_s
+  end
+
+  def validate_preview_tags raw, errors, warnings
+    names = raw.to_s.split
+    return if names.empty?
+    if names.any? { _1.downcase.start_with?('nico:') }
+      errors[:tags] = ['ニコニコ・タグは直接指定できません．']
+      return
+    end
+
+    parsed = names.map { |name| TagName.canonicalise(name.sub(/\[.*\]\z/, '')).first }
+    existing = Tag.joins(:tag_name).where(tag_names: { name: parsed }).includes(:tag_name).to_a
+    deprecated = existing.select(&:deprecated?).map(&:name)
+    errors[:tags] = ["廃止済みタグがあります: #{ deprecated.join(' ') }"] if deprecated.present?
+    known = existing.reject(&:deprecated?).map(&:name)
+    new_tags = parsed.uniq - known
+    warnings << "新規タグを作成します: #{ new_tags.join(' ') }" if new_tags.present?
+  rescue Tag::SectionLiteralParseError
+    errors[:tags] = ['タグ区間の記法が不正です．']
+  end
+
+  def validate_basic_data attributes, errors
+    post = Post.new(title: attributes['title'].presence,
+                    url: attributes['url'],
+                    thumbnail_base: attributes['thumbnail_base'].presence,
+                    original_created_from: attributes['original_created_from'].presence,
+                    original_created_before: attributes['original_created_before'].presence,
+                    video_ms: parse_duration(attributes['duration'], errors))
+    post.valid?
+    post.errors.each do |error|
+      next if error.attribute == :url && error.type == :taken
+
+      (errors[error.attribute] ||= []) << error.message
+    end
+  end
+
+  def parse_duration value, errors
+    return nil if value.blank?
+
+    value.is_a?(Numeric) ? value.to_i : Tag.time_to_ms!(value.to_s, tag_name: '動画時間')
+  rescue Tag::SectionLiteralParseError
+    errors[:video_ms] = ['動画時間の記法が不正です．']
+    nil
+  end
+
+  def validate_parents raw, errors
+    ids = raw.to_s.split.map { Integer(_1, exception: false) }
+    return if ids.compact.empty? && raw.to_s.blank?
+
+    errors[:parent_post_ids] = ['親投稿 Id. が不正です．'] and return if ids.any? { _1.nil? || _1 <= 0 }
+    if Post.where(id: ids).count != ids.uniq.length
+      errors[:parent_post_ids] = ['存在しない親投稿 Id. があります．']
+    end
+  end
+end

backend/app/services/post_import_row_normaliser.rb

@@ -0,0 +1,162 @@
+class PostImportRowNormaliser
+  ORIGINS = ['automatic', 'manual'].freeze
+  STRING_FIELDS = [
+    'title',
+    'thumbnail_base',
+    'original_created_from',
+    'original_created_before',
+    'tags',
+    'parent_post_ids',
+  ].freeze
+  FLEXIBLE_FIELDS = ['duration', 'video_ms'].freeze
+  ATTRIBUTE_FIELDS = (STRING_FIELDS + FLEXIBLE_FIELDS).freeze
+
+  def self.normalise! rows, allow_warning_fields: false
+    raise ArgumentError, '取込行の形式が不正です．' unless rows.is_a?(Array)
+    raise ArgumentError, '取込件数が多すぎます．' if rows.length > PostImportUrlListParser::MAX_ROWS
+
+    normalised_rows = rows.map { normalise_row!(_1, allow_warning_fields:) }
+    source_rows = normalised_rows.map { _1['source_row'] }
+    raise ArgumentError, '元行番号が重複しています．' if source_rows.uniq.length != source_rows.length
+    if normalised_rows.sum { row_bytesize(_1) } > PostImportUrlListParser::MAX_BYTES
+      raise ArgumentError, '取込データが大きすぎます．'
+    end
+
+    normalised_rows
+  end
+
+  def self.normalise_row! row, allow_warning_fields:
+    unless row.is_a?(Hash) || row.is_a?(ActionController::Parameters)
+      raise ArgumentError, '取込行の形式が不正です．'
+    end
+
+    parameters =
+        row.is_a?(ActionController::Parameters) ? row : ActionController::Parameters.new(row)
+    permitted = parameters.permit(*permitted_keys(allow_warning_fields))
+    normalised = permitted.to_h.deep_transform_keys { _1.to_s.underscore }
+
+    normalised['source_row'] = normalise_source_row!(normalised['source_row'])
+    normalise_url!(normalised['url'])
+    normalise_metadata_url!(normalised['metadata_url'])
+    normalise_attributes!(normalised.fetch('attributes', { }))
+    normalise_provenance!(normalised.fetch('provenance', { }))
+    normalise_tag_sources!(normalised['tag_sources'])
+    normalise_warning_values!(normalised, allow_warning_fields:)
+    if row_bytesize(normalised) > PostImportUrlListParser::MAX_BYTES
+      raise ArgumentError, '取込行が大きすぎます．'
+    end
+
+    normalised
+  end
+
+  def self.permitted_keys allow_warning_fields
+    keys = [
+      :source_row,
+      :sourceRow,
+      :url,
+      :metadata_url,
+      :metadataUrl,
+      { attributes: {} },
+      { provenance: {} },
+      { tag_sources: {} },
+      { tagSources: {} },
+    ]
+    return keys unless allow_warning_fields
+
+    keys + [
+      { fetch_warnings: [] },
+      { fetchWarnings: [] },
+      { validation_warnings: [] },
+      { validationWarnings: [] },
+    ]
+  end
+  private_class_method :permitted_keys
+
+  def self.normalise_source_row! value
+    source_row = Integer(value, exception: false)
+    raise ArgumentError, '元行番号が不正です．' if source_row.nil? || source_row <= 0
+
+    source_row
+  end
+  private_class_method :normalise_source_row!
+
+  def self.normalise_url! value
+    raise ArgumentError, 'URL の形式が不正です．' unless value.is_a?(String)
+    raise ArgumentError, 'URL が長すぎます．' if value.bytesize > PostImportUrlListParser::MAX_URL_BYTES
+  end
+  private_class_method :normalise_url!
+
+  def self.normalise_metadata_url! value
+    raise ArgumentError, 'metadata_url の形式が不正です．' unless value.nil? || value.is_a?(String)
+    if value.to_s.bytesize > PostImportUrlListParser::MAX_URL_BYTES
+      raise ArgumentError, 'metadata_url が長すぎます．'
+    end
+  end
+  private_class_method :normalise_metadata_url!
+
+  def self.normalise_attributes! attributes
+    raise ArgumentError, 'attributes の形式が不正です．' unless attributes.is_a?(Hash)
+    raise ArgumentError, '取込項目が不正です．' unless (attributes.keys - ATTRIBUTE_FIELDS).empty?
+
+    attributes.each do |key, value|
+      case key
+      when *STRING_FIELDS
+        raise ArgumentError, '取込項目の型が不正です．' unless value.nil? || value.is_a?(String)
+      when *FLEXIBLE_FIELDS
+        unless value.nil? || value.is_a?(String) || value.is_a?(Numeric)
+          raise ArgumentError, '取込項目の型が不正です．'
+        end
+      end
+      if value.to_s.bytesize > PostImportUrlListParser::MAX_URL_BYTES
+        raise ArgumentError, '取込項目が大きすぎます．'
+      end
+    end
+  end
+  private_class_method :normalise_attributes!
+
+  def self.normalise_provenance! provenance
+    raise ArgumentError, 'provenance の形式が不正です．' unless provenance.is_a?(Hash)
+
+    allowed = ATTRIBUTE_FIELDS + ['url']
+    raise ArgumentError, '値の由来が不正です．' unless (provenance.keys - allowed).empty?
+    raise ArgumentError, '値の由来が不正です．' unless provenance.values.all? { ORIGINS.include?(_1) }
+  end
+  private_class_method :normalise_provenance!
+
+  def self.normalise_tag_sources! tag_sources
+    return if tag_sources.nil?
+
+    raise ArgumentError, 'タグ由来の形式が不正です．' unless tag_sources.is_a?(Hash)
+    raise ArgumentError, 'タグ由来の形式が不正です．' unless (tag_sources.keys - ORIGINS).empty?
+    raise ArgumentError, 'タグ由来の形式が不正です．' unless tag_sources.values.all? { _1.is_a?(String) }
+    if tag_sources.values.any? { _1.bytesize > PostImportUrlListParser::MAX_URL_BYTES }
+      raise ArgumentError, 'タグ由来が大きすぎます．'
+    end
+    if tag_sources.values.sum(&:bytesize) > PostImportUrlListParser::MAX_URL_BYTES
+      raise ArgumentError, 'タグ由来が大きすぎます．'
+    end
+  end
+  private_class_method :normalise_tag_sources!
+
+  def self.normalise_warning_values! normalised, allow_warning_fields:
+    return unless allow_warning_fields
+
+    %w[fetch_warnings validation_warnings].each do |field|
+      values = normalised[field]
+      next if values.nil?
+
+      unless values.is_a?(Array) && values.all? { _1.is_a?(String) }
+        raise ArgumentError, '警告の形式が不正です．'
+      end
+      if values.any? { _1.bytesize > PostImportUrlListParser::MAX_URL_BYTES }
+        raise ArgumentError, '警告が大きすぎます．'
+      end
+    end
+  end
+  private_class_method :normalise_warning_values!
+
+  def self.row_bytesize row
+    row.to_json.bytesize
+  end
+  private_class_method :row_bytesize
+end

backend/app/services/post_import_runner.rb

@@ -0,0 +1,64 @@
+class PostImportRunner
+  def initialize actor:, rows:, existing: 'skip'
+    @actor = actor
+    @rows = rows
+    @existing = existing == 'error' ? 'error' : 'skip'
+  end
+
+  def run
+    normalised_rows = PostImportRowNormaliser.normalise!(@rows)
+
+    results = normalised_rows.map { |row| run_row(row) }
+    {
+      created: results.count { _1[:status] == 'created' },
+      skipped: results.count { _1[:status] == 'skipped' },
+      failed: results.count { _1[:status] == 'failed' },
+      rows: results,
+    }
+  end
+
+  private
+
+  def run_row row
+    attributes = row.fetch('attributes', { }).transform_keys { _1.to_s.underscore }
+    preview = PostImportPreviewer.new(existing: @existing)
+      .preview_rows(
+        rows: [{
+          source_row: row['source_row'],
+          url: row['url'],
+          attributes:,
+          provenance: row['provenance'],
+          tag_sources: row['tag_sources'],
+        }],
+        fetch_metadata: false).first
+    if @existing == 'skip' && preview[:existing]
+      return row.slice('source_row').merge(status: 'skipped')
+    end
+
+    if preview[:validation_errors].present?
+      return {
+        source_row: row['source_row'],
+        status: 'failed',
+        errors: preview[:validation_errors],
+      }
+    end
+
+    attributes['tags'] = preview[:attributes]['tags']
+    attributes['url'] = row['url']
+    post = PostCreator.new(actor: @actor, attributes:).create!
+    { source_row: row['source_row'], status: 'created', post: PostRepr.base(post) }
+  rescue ActiveRecord::RecordInvalid => e
+    { source_row: row['source_row'], status: 'failed', errors: e.record.errors.to_hash }
+  rescue Tag::NicoTagNormalisationError
+    { source_row: row['source_row'], status: 'failed', errors: { tags: ['ニコニコ・タグは直接指定できません．'] } }
+  rescue Tag::DeprecatedTagNormalisationError
+    { source_row: row['source_row'], status: 'failed', errors: { tags: ['廃止済みタグは付与できません．'] } }
+  rescue ArgumentError, PostCreator::VideoMsParseError
+    { source_row: row['source_row'], status: 'failed', errors: { base: ['入力値が不正です．'] } }
+  rescue StandardError => e
+    Rails.logger.error(
+      "post_import_runner_failure #{ { error: e.class.name, message: e.message }.to_json }",
+    )
+    { source_row: row['source_row'], status: 'failed', errors: { base: ['登録中にエラーが発生しました．'] } }
+  end
+end

backend/app/services/post_import_url_list_parser.rb

@@ -0,0 +1,23 @@
+class PostImportUrlListParser
+  MAX_ROWS = 100
+  MAX_BYTES = 1.megabyte
+  MAX_URL_BYTES = 20.kilobytes
+
+  def self.parse source
+    raw = source.to_s
+    raise ArgumentError, '入力が大きすぎます．' if raw.bytesize > MAX_BYTES
+
+    rows = raw.split(/\r\n|\n|\r/).each_with_index.filter_map { |line, index|
+      url = line.strip
+      next if url.blank?
+
+      raise ArgumentError, 'URL が長すぎます．' if url.bytesize > MAX_URL_BYTES
+
+      { source_row: index + 1, url: }
+    }
+    raise ArgumentError, 'URL を入力してください．' if rows.empty?
+    raise ArgumentError, "取込件数は #{ MAX_ROWS } 件までです．" if rows.length > MAX_ROWS
+
+    rows
+  end
+end

backend/app/services/post_metadata_fetcher.rb

@@ -0,0 +1,60 @@
+class PostMetadataFetcher
+  def self.fetch raw_url
+    uri, = Preview::UrlSafety.validate(raw_url)
+    response = Preview::HttpFetcher.fetch(
+      uri.to_s,
+      max_bytes: Preview::ThumbnailFetcher::HTML_MAX_BYTES,
+    )
+    metadata = Preview::HtmlMetadataExtractor.extract(response)
+    document = Nokogiri::HTML.parse(response.body)
+    content = lambda { |name|
+      document
+        .at_css("meta[property='#{ name }'], meta[name='#{ name }']")
+        &.[]('content')
+        &.strip
+        &.presence
+    }
+    duration = content.call('og:video:duration') || content.call('video:duration')
+    published = content.call('article:published_time') || content.call('date')
+    created_range = original_created_range(published)
+    platform_tags = platform_tags(uri)
+    { title: metadata[:title],
+      thumbnail_base: Preview::KnownSiteExtractor.thumbnail_url(uri) || metadata[:image_url],
+      original_created_from: created_range&.first&.iso8601,
+      original_created_before: created_range&.last&.iso8601,
+      duration: duration&.to_f&.then { _1.positive? ? (_1 * 1_000).round : nil },
+      tags: platform_tags.join(' ') }
+  end
+
+  def self.platform_tags uri
+    return ['動画', 'YouTube'] if Preview::KnownSiteExtractor.youtube_video_id(uri)
+    return ['動画', 'ニコニコ'] if Preview::KnownSiteExtractor.niconico_video_id(uri)
+
+    []
+  end
+
+  def self.original_created_range value
+    return nil if value.blank?
+
+    raw = value.to_s.strip
+    from = Time.zone.parse(raw)
+    zone = '(?:Z|[+-]\d{2}:?\d{2})?'
+    before =
+      case raw
+      when /\A\d{4}\z/ then from + 1.year
+      when /\A\d{4}-\d{2}\z/ then from + 1.month
+      when /\A\d{4}-\d{2}-\d{2}\z/ then from + 1.day
+      when /\A\d{4}-\d{2}-\d{2}T\d{2}#{ zone }\z/ then from + 1.hour
+      when /\A\d{4}-\d{2}-\d{2}T\d{2}:\d{2}#{ zone }\z/ then from + 1.minute
+      when /\A\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}#{ zone }\z/ then from + 1.second
+      when /\A\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.(\d+)#{ zone }\z/
+        from + (10**(-Regexp.last_match(1).length))
+      else
+        return nil
+      end
+    [from, before]
+  rescue ArgumentError, TypeError
+    nil
+  end
+  private_class_method :platform_tags, :original_created_range
+end

backend/app/services/post_url_normaliser.rb

@@ -0,0 +1,13 @@
+class PostUrlNormaliser
+  def self.normalise raw_url
+    value = raw_url.to_s.strip
+    uri = URI.parse(value)
+    return nil unless uri.is_a?(URI::HTTP) && uri.host.present?
+
+    uri.host = uri.host.downcase
+    uri.path = uri.path.sub(/\/\z/, '') if uri.path.present?
+    uri.to_s
+  rescue URI::InvalidURIError
+    nil
+  end
+end

backend/app/services/preview/http_fetcher.rb

@@ -12,8 +12,12 @@ module Preview
 
     Response = Data.define(:body, :content_type, :url)
 
-    def self.fetch(raw_url, max_bytes: DEFAULT_MAX_BYTES, redirects: MAX_REDIRECTS)
+    def self.fetch(raw_url, max_bytes: DEFAULT_MAX_BYTES, redirects: MAX_REDIRECTS,
+                   allowed_hosts: nil)
       uri, addresses = UrlSafety.validate(raw_url)
+      if allowed_hosts && !allowed_hosts.include?(uri.host.downcase)
+        raise FetchFailed, '許可されてゐない redirect 先です．'
+      end
       response = request(uri, addresses.first, max_bytes)
 
       if response.is_a?(Net::HTTPRedirection)
@@ -50,7 +54,7 @@ module Preview
               raise FetchFailed, 'redirect 先が不正です．'
             end
 
-        return fetch(redirect_url, max_bytes:, redirects: redirects - 1)
+        return fetch(redirect_url, max_bytes:, redirects: redirects - 1, allowed_hosts:)
       end
 
       unless response.is_a?(Net::HTTPSuccess)
@@ -67,7 +71,10 @@ module Preview
       log_failure(:timeout, url: uri&.to_s || raw_url, error: e.class.name, message: e.message)
       raise FetchTimeout, e.message
     rescue SocketError, SystemCallError, OpenSSL::SSL::SSLError, EOFError => e
-      log_failure(:network_error, url: uri&.to_s || raw_url, error: e.class.name, message: e.message)
+      log_failure(:network_error,
+                  url: uri&.to_s || raw_url,
+                  error: e.class.name,
+                  message: e.message)
       raise FetchFailed, e.message
     end
 

backend/app/services/preview/known_site_extractor.rb

@@ -4,6 +4,15 @@ module Preview
       youtube_thumbnail(uri)
     end
 
+    def self.youtube_video_id(uri)
+      case uri.host&.downcase
+      when 'youtu.be'
+        uri.path.split('/').reject(&:blank?).first
+      when 'www.youtube.com', 'youtube.com', 'm.youtube.com'
+        uri.path == '/watch' ? URI.decode_www_form(uri.query.to_s).to_h['v'] : nil
+      end&.then { _1 if _1.match?(/\A[A-Za-z0-9_-]{6,20}\z/) }
+    end
+
     def self.niconico_video_id(uri)
       case uri.host&.downcase
       when 'www.nicovideo.jp', 'nicovideo.jp'
@@ -14,14 +23,8 @@ module Preview
     end
 
     def self.youtube_thumbnail(uri)
-      id =
+      id = youtube_video_id(uri)
-          case uri.host&.downcase
+      return unless id
-          when 'youtu.be'
-            uri.path.split('/').reject(&:blank?).first
-          when 'www.youtube.com', 'youtube.com', 'm.youtube.com'
-            uri.path == '/watch' ? URI.decode_www_form(uri.query.to_s).to_h['v'] : nil
-          end
-      return unless id&.match?(/\A[A-Za-z0-9_-]{6,20}\z/)
 
       "https://i.ytimg.com/vi/#{ id }/hqdefault.jpg"
     end

backend/config/routes.rb

@@ -33,6 +33,12 @@ Rails.application.routes.draw do
     get :thumbnail
   end
 
+  scope 'posts/import', controller: :post_imports do
+    post :preview
+    post :validate
+    post '', action: :create
+  end
+
   resources :wiki_pages, path: 'wiki', only: [:index, :show, :create, :update] do
     collection do
       get :search

frontend/src/App.tsx

@@ -41,6 +41,9 @@ import NotFound from '@/pages/NotFound'
 import TOSPage from '@/pages/TOSPage.mdx'
 import PostDetailPage from '@/pages/posts/PostDetailPage'
 import PostHistoryPage from '@/pages/posts/PostHistoryPage'
+import PostImportResultPage from '@/pages/posts/PostImportResultPage'
+import PostImportReviewPage from '@/pages/posts/PostImportReviewPage'
+import PostImportSourcePage from '@/pages/posts/PostImportSourcePage'
 import PostListPage from '@/pages/posts/PostListPage'
 import PostNewPage from '@/pages/posts/PostNewPage'
 import PostSearchPage from '@/pages/posts/PostSearchPage'
@@ -75,6 +78,9 @@ const RouteTransitionWrapper = ({ animationMode, user, setUser }: {
 	    <Route path="/" element={<Navigate to="/posts" replace/>}/>
 	    <Route path="/posts" element={<PostListPage/>}/>
 	    <Route path="/posts/new" element={<PostNewPage user={user}/>}/>
+	    <Route path="/posts/import" element={<PostImportSourcePage user={user}/>}/>
+	    <Route path="/posts/import/:sessionId/review" element={<PostImportReviewPage user={user}/>}/>
+	    <Route path="/posts/import/:sessionId/result" element={<PostImportResultPage user={user}/>}/>
 	    <Route path="/posts/search" element={<PostSearchPage/>}/>
 	    <Route path="/posts/:id" element={<PostDetailRoute user={user}/>}/>
 	    <Route path="/posts/changes" element={<PostHistoryPage/>}/>
@@ -113,6 +119,9 @@ const RouteTransitionWrapper = ({ animationMode, user, setUser }: {
 	  <Route path="/" element={<Navigate to="/posts" replace/>}/>
 	  <Route path="/posts" element={<PostListPage/>}/>
 	  <Route path="/posts/new" element={<PostNewPage user={user}/>}/>
+	  <Route path="/posts/import" element={<PostImportSourcePage user={user}/>}/>
+	  <Route path="/posts/import/:sessionId/review" element={<PostImportReviewPage user={user}/>}/>
+	  <Route path="/posts/import/:sessionId/result" element={<PostImportResultPage user={user}/>}/>
 	  <Route path="/posts/search" element={<PostSearchPage/>}/>
 	  <Route path="/posts/:id" element={<PostDetailRoute user={user}/>}/>
 	  <Route path="/posts/changes" element={<PostHistoryPage/>}/>

frontend/src/components/TopNav.tsx

@@ -26,7 +26,7 @@ export const menuOutline = (
 	tag?: Tag | null
 	material?: Material | null
 	wikiId: number | null
-	user: User | null,
+	user: User | null
 	pathName: string },
 ): Menu => {
   const postCount = tag?.postCount ?? material?.tag?.postCount ?? 0
@@ -43,6 +43,7 @@ export const menuOutline = (
 	  { name: '一覧', to: '/posts' },
 	  { name: '検索', to: '/posts/search' },
 	  { name: '追加', to: '/posts/new' },
+	  { name: '取込', to: '/posts/import' },
 	  { name: '全体履歴', to: '/posts/changes' },
 	  { name: 'ヘルプ', to: '/wiki/ヘルプ:広場' }] },
       { name: 'タグ', to: '/tags', subMenu: [

frontend/src/components/posts/import/PostImportRowDialog.tsx

@@ -0,0 +1,203 @@
+import FieldError from '@/components/common/FieldError'
+import PostImportStatusBadge from '@/components/posts/import/PostImportStatusBadge'
+import ThumbnailPreview from '@/components/posts/import/ThumbnailPreview'
+import { Button } from '@/components/ui/button'
+import { Dialog,
+	 DialogContent,
+	 DialogDescription,
+	 DialogFooter,
+	 DialogHeader,
+	 DialogTitle } from '@/components/ui/dialog'
+import { inputClass } from '@/lib/utils'
+
+import type { FC } from 'react'
+import { useEffect, useState } from 'react'
+
+import type { PostImportOrigin,
+	      PostImportRow } from '@/lib/postImportSession'
+
+type Draft = {
+    url:                   string
+    title:                 string
+    thumbnailBase:         string
+    originalCreatedFrom:   string
+    originalCreatedBefore: string
+    duration:              string
+    tags:                  string
+    parentPostIds:         string }
+
+type Props = {
+    open:         boolean
+    row:          PostImportRow | null
+    saving:       boolean
+    onOpenChange: (open: boolean) => void
+    onSave:       (draft: Draft) => Promise<boolean> }
+
+const originOf = (
+    row:   PostImportRow,
+    field: string,
+): PostImportOrigin =>
+    row.provenance[field] ?? 'automatic'
+
+const buildDraft = (row: PostImportRow): Draft => ({
+    url: row.url,
+    title: String (row.attributes.title ?? ''),
+    thumbnailBase: String (row.attributes.thumbnailBase ?? ''),
+    originalCreatedFrom: String (row.attributes.originalCreatedFrom ?? ''),
+    originalCreatedBefore: String (row.attributes.originalCreatedBefore ?? ''),
+    duration: String (row.attributes.duration ?? ''),
+    tags: String (row.attributes.tags ?? ''),
+    parentPostIds: String (row.attributes.parentPostIds ?? '') })
+
+
+const PostImportRowDialog: FC<Props> = (
+    { open, row, saving, onOpenChange, onSave },
+) => {
+    const [draft, setDraft] = useState<Draft | null> (null)
+
+    useEffect (() => {
+	if (open && row)
+	  setDraft (buildDraft (row))
+    }, [open, row])
+
+    if (!(row) || !(draft))
+      return null
+
+    const update = <Key extends keyof Draft,> (
+	key:   Key,
+	value: Draft[Key],
+    ) => {
+	setDraft (current =>
+	    current ? { ...current, [key]: value } : current)
+    }
+
+    const save = async () => {
+	if (await onSave (draft))
+	  onOpenChange (false)
+    }
+
+    return (
+	<Dialog open={open} onOpenChange={onOpenChange}>
+	  <DialogContent className="max-w-3xl px-6 pb-6 pt-7">
+	    <DialogHeader className="pl-8">
+	      <DialogTitle>投稿 {row.sourceRow} を編集</DialogTitle>
+	      <DialogDescription>
+		自動取得結果を確認し、必要な項目だけ修正してください．
+	      </DialogDescription>
+	    </DialogHeader>
+
+	    <div className="grid gap-6 md:grid-cols-[7rem_minmax(0,1fr)]">
+	      <div className="space-y-3">
+		<ThumbnailPreview
+		    url={draft.thumbnailBase}
+		    className="h-28 w-28"/>
+		<div className="flex flex-wrap gap-2">
+		  <PostImportStatusBadge value={row.status}/>
+		  <PostImportStatusBadge value={row.importStatus ?? 'pending'}/>
+		</div>
+	      </div>
+
+	      <div className="space-y-4">
+		<DialogField
+		    label="URL"
+		    value={draft.url}
+		    origin={originOf (row, 'url')}
+		    onChange={value => update ('url', value)}/>
+		<DialogField
+		    label="タイトル"
+		    value={draft.title}
+		    origin={originOf (row, 'title')}
+		    onChange={value => update ('title', value)}/>
+		<DialogField
+		    label="サムネール基底 URL"
+		    value={draft.thumbnailBase}
+		    origin={originOf (row, 'thumbnailBase')}
+		    onChange={value => update ('thumbnailBase', value)}/>
+		<div className="grid gap-4 md:grid-cols-2">
+		  <DialogField
+		      label="作成日時 From"
+		      value={draft.originalCreatedFrom}
+		      origin={originOf (row, 'originalCreatedFrom')}
+		      onChange={value => update ('originalCreatedFrom', value)}/>
+		  <DialogField
+		      label="作成日時 Before"
+		      value={draft.originalCreatedBefore}
+		      origin={originOf (row, 'originalCreatedBefore')}
+		      onChange={value => update ('originalCreatedBefore', value)}/>
+		</div>
+		<DialogField
+		    label="動画時間"
+		    value={draft.duration}
+		    origin={originOf (row, 'duration')}
+		    onChange={value => update ('duration', value)}/>
+		<DialogArea
+		    label="タグ"
+		    value={draft.tags}
+		    origin={originOf (row, 'tags')}
+		    onChange={value => update ('tags', value)}/>
+		<DialogField
+		    label="親投稿"
+		    value={draft.parentPostIds}
+		    origin={originOf (row, 'parentPostIds')}
+		    onChange={value => update ('parentPostIds', value)}/>
+		<FieldError messages={Object.values (row.validationErrors ?? { }).flat ()}/>
+		<FieldError messages={Object.values (row.importErrors ?? { }).flat ()}/>
+	      </div>
+	    </div>
+
+	    <DialogFooter>
+	      <Button
+		  type="button"
+		  variant="outline"
+		  onClick={() => onOpenChange (false)}>
+		取消し
+	      </Button>
+	      <Button
+		  type="button"
+		  onClick={save}
+		  disabled={saving}>
+		保存
+	      </Button>
+	    </DialogFooter>
+	  </DialogContent>
+	</Dialog>)
+}
+
+const DialogField = (
+    { label, value, origin, onChange }: {
+	label:    string
+	value:    string
+	origin:   PostImportOrigin
+	onChange: (value: string) => void },
+) => (
+    <label className="block space-y-1">
+      <span className="flex items-center gap-2 text-sm font-medium">
+	{label}
+	<PostImportStatusBadge value={origin}/>
+      </span>
+      <input
+	  value={value}
+	  onChange={ev => onChange (ev.target.value)}
+	  className={inputClass (false)}/>
+    </label>)
+
+const DialogArea = (
+    { label, value, origin, onChange }: {
+	label:    string
+	value:    string
+	origin:   PostImportOrigin
+	onChange: (value: string) => void },
+) => (
+    <label className="block space-y-1">
+      <span className="flex items-center gap-2 text-sm font-medium">
+	{label}
+	<PostImportStatusBadge value={origin}/>
+      </span>
+      <textarea
+	  value={value}
+	  rows={4}
+	  onChange={ev => onChange (ev.target.value)}
+	  className={inputClass (false)}/>
+    </label>)
+
+export default PostImportRowDialog

frontend/src/components/posts/import/PostImportRowSummary.tsx

@@ -0,0 +1,149 @@
+import { Button } from '@/components/ui/button'
+import { cn } from '@/lib/utils'
+
+import PostImportStatusBadge from '@/components/posts/import/PostImportStatusBadge'
+import ThumbnailPreview from '@/components/posts/import/ThumbnailPreview'
+
+import type { FC } from 'react'
+
+import type { PostImportRow } from '@/lib/postImportSession'
+
+type Props = {
+    row:     PostImportRow
+    onEdit:  () => void }
+
+const toneClass = (row: PostImportRow): string[] => {
+    const value = row.importStatus ?? row.status
+    switch (value)
+      {
+      case 'created':
+	return [
+	    'border-sky-200 bg-sky-50',
+	    'dark:border-sky-900 dark:bg-sky-950/30']
+      case 'skipped':
+	return [
+	    'border-stone-200 bg-stone-50',
+	    'dark:border-stone-800 dark:bg-stone-900/60']
+      case 'failed':
+      case 'error':
+	return [
+	    'border-rose-200 bg-rose-50',
+	    'dark:border-rose-900 dark:bg-rose-950/30']
+      case 'warning':
+	return [
+	    'border-amber-200 bg-amber-50',
+	    'dark:border-amber-900 dark:bg-amber-950/30']
+      default:
+	return [
+	    'border-border bg-white',
+	    'dark:border-neutral-700 dark:bg-neutral-900']
+      }
+}
+
+const summaryError = (row: PostImportRow): string | null => {
+    const validation = Object.values (row.validationErrors ?? { }).flat ()[0]
+    if (validation)
+      return validation
+
+    return Object.values (row.importErrors ?? { }).flat ()[0] ?? null
+}
+
+const summaryDate = (row: PostImportRow): string =>
+    [row.attributes.originalCreatedFrom, row.attributes.originalCreatedBefore]
+	.filter (_1 => typeof _1 === 'string' && _1 !== '')
+	.join (' ～ ')
+
+
+const PostImportRowSummary: FC<Props> = ({ row, onEdit }) => {
+    const error = summaryError (row)
+    const importStatus = row.importStatus ?? 'pending'
+
+    return (
+	<>
+	  <div
+	      className={cn (
+		  'hidden items-center gap-4 rounded-lg border p-4 md:grid',
+		  'md:grid-cols-[4rem_5rem_minmax(0,1fr)_auto_auto_auto]',
+		  toneClass (row),
+		  'hover:bg-slate-50',
+		  'dark:hover:bg-neutral-800',
+	      )}>
+	    <div className="space-y-1">
+	      <div className="text-sm font-medium">#{row.sourceRow}</div>
+	      <PostImportStatusBadge value={row.status}/>
+	    </div>
+	    <ThumbnailPreview
+		url={String (row.attributes.thumbnailBase ?? '')}
+		className="h-16 w-16"/>
+	    <div className="min-w-0 space-y-1">
+	      <div className="line-clamp-2 text-sm font-medium">
+		{String (row.attributes.title ?? '') || '（タイトル未取得）'}
+	      </div>
+	      <div className="truncate text-xs text-neutral-600 dark:text-neutral-300">
+		{row.url}
+	      </div>
+	      <div className="truncate text-xs text-neutral-500 dark:text-neutral-400">
+		{String (row.attributes.tags ?? '') || 'タグなし'}
+	      </div>
+	      <div className="text-xs text-neutral-500 dark:text-neutral-400">
+		{summaryDate (row) || '日時未取得'}
+		{row.attributes.duration ? ` / ${ row.attributes.duration }` : ''}
+	      </div>
+	    </div>
+	    <div className="space-y-1">
+	      <PostImportStatusBadge value={importStatus}/>
+	    </div>
+	    <div className="space-y-1">
+	      {error
+	       ? <PostImportStatusBadge value="error"/>
+	       : <PostImportStatusBadge value="ready"/>}
+	    </div>
+	    <div className="flex justify-end">
+	      <Button
+		  type="button"
+		  variant="outline"
+		  onClick={onEdit}
+		  disabled={row.importStatus === 'created'}>
+		編集
+	      </Button>
+	    </div>
+	  </div>
+
+	  <div
+	      className={cn (
+		  'space-y-3 rounded-lg border p-4 md:hidden',
+		  toneClass (row),
+	      )}>
+	    <div className="flex items-start gap-3">
+	      <ThumbnailPreview
+		  url={String (row.attributes.thumbnailBase ?? '')}
+		  className="h-20 w-20 shrink-0"/>
+	      <div className="min-w-0 flex-1 space-y-2">
+		<div className="line-clamp-2 text-sm font-medium">
+		  {String (row.attributes.title ?? '') || '（タイトル未取得）'}
+		</div>
+		<div className="truncate text-xs text-neutral-600 dark:text-neutral-300">
+		  {row.url}
+		</div>
+		<div className="flex flex-wrap gap-2">
+		  <PostImportStatusBadge value={row.status}/>
+		  <PostImportStatusBadge value={importStatus}/>
+		</div>
+		{error && (
+		    <div className="text-xs text-red-700 dark:text-red-200">
+		      {error}
+		    </div>)}
+	      </div>
+	    </div>
+	    <Button
+		type="button"
+		variant="outline"
+		onClick={onEdit}
+		disabled={row.importStatus === 'created'}>
+	      編集
+	    </Button>
+	  </div>
+	</>)
+}
+
+export default PostImportRowSummary

frontend/src/components/posts/import/PostImportStatusBadge.tsx

@@ -0,0 +1,70 @@
+import { cn } from '@/lib/utils'
+
+import type { FC } from 'react'
+
+import type { PostImportOrigin } from '@/lib/postImportSession'
+
+type BadgeValue =
+    'ready'
+    | 'warning'
+    | 'error'
+    | 'pending'
+    | 'created'
+    | 'skipped'
+    | 'failed'
+    | PostImportOrigin
+
+type Props = {
+    value: BadgeValue }
+
+const LABELS: Record<BadgeValue, string> = {
+    ready:     '登録可能',
+    warning:   '警告',
+    error:     '要修正',
+    pending:   '未登録',
+    created:   '登録済み',
+    skipped:   'スキップ',
+    failed:    '失敗',
+    automatic: '自動取得',
+    manual:    '手修正' }
+
+const STYLES: Record<BadgeValue, string[]> = {
+    ready: [
+	'border-emerald-300 bg-emerald-50 text-emerald-700',
+	'dark:border-emerald-900 dark:bg-emerald-950 dark:text-emerald-200'],
+    warning: [
+	'border-amber-300 bg-amber-50 text-amber-700',
+	'dark:border-amber-900 dark:bg-amber-950 dark:text-amber-200'],
+    error: [
+	'border-red-300 bg-red-50 text-red-700',
+	'dark:border-red-900 dark:bg-red-950 dark:text-red-200'],
+    pending: [
+	'border-slate-300 bg-slate-50 text-slate-700',
+	'dark:border-slate-700 dark:bg-slate-900 dark:text-slate-200'],
+    created: [
+	'border-sky-300 bg-sky-50 text-sky-700',
+	'dark:border-sky-900 dark:bg-sky-950 dark:text-sky-200'],
+    skipped: [
+	'border-stone-300 bg-stone-50 text-stone-700',
+	'dark:border-stone-700 dark:bg-stone-900 dark:text-stone-200'],
+    failed: [
+	'border-rose-300 bg-rose-50 text-rose-700',
+	'dark:border-rose-900 dark:bg-rose-950 dark:text-rose-200'],
+    automatic: [
+	'border-slate-300 bg-slate-50 text-slate-700',
+	'dark:border-slate-700 dark:bg-slate-900 dark:text-slate-200'],
+    manual: [
+	'border-purple-300 bg-purple-50 text-purple-700',
+	'dark:border-purple-900 dark:bg-purple-950 dark:text-purple-200'] }
+
+
+const PostImportStatusBadge: FC<Props> = ({ value }) => (
+    <span
+	className={cn (
+	    'inline-flex items-center rounded-full border px-2.5 py-1 text-xs font-medium',
+	    STYLES[value],
+	)}>
+      {LABELS[value]}
+    </span>)
+
+export default PostImportStatusBadge

frontend/src/components/posts/import/ThumbnailPreview.tsx

@@ -0,0 +1,48 @@
+import { useEffect, useState } from 'react'
+
+import type { FC } from 'react'
+
+
+type Props = {
+    url:       string
+    alt?:      string
+    className?: string }
+
+
+const ThumbnailPreview: FC<Props> = ({ url, alt = 'サムネール', className = 'h-16 w-16' }) => {
+    const [failed, setFailed] = useState (false)
+
+    useEffect (() => {
+	setFailed (false)
+    }, [url])
+
+    if (!(url))
+      {
+	return (
+	    <div
+		className={`${ className } flex items-center justify-center rounded border
+			    border-border bg-muted text-xs text-muted-foreground`}>
+	      なし
+	    </div>)
+      }
+
+    if (failed)
+      {
+	return (
+	    <div
+		className={`${ className } flex items-center justify-center rounded border
+			    border-red-300 bg-red-50 p-2 text-center text-xs text-red-700
+			    dark:border-red-900 dark:bg-red-950 dark:text-red-200`}>
+	      表示不可
+	    </div>)
+      }
+
+    return (
+	<img
+	    src={url}
+	    alt={alt}
+	    className={`${ className } rounded border border-border object-cover`}
+	    onError={() => setFailed (true)}/>)
+}
+
+export default ThumbnailPreview

frontend/src/lib/postImportSession.ts

@@ -0,0 +1,221 @@
+export type PostImportOrigin = 'automatic' | 'manual'
+export type PostImportRepairMode = 'all' | 'failed'
+export type PostImportStatus =
+    'pending'
+    | 'created'
+    | 'skipped'
+    | 'failed'
+export type PostImportResultStatus = 'created' | 'skipped' | 'failed'
+export type PostImportAttributeValue = string | number
+
+export type PostImportRow = {
+    sourceRow:         number
+    url:               string
+    attributes:        Record<string, PostImportAttributeValue>
+    warnings:          string[]
+    validationErrors:  Record<string, string[]>
+    importErrors?:     Record<string, string[]>
+    provenance:        Record<string, PostImportOrigin>
+    tagSources?:       Record<PostImportOrigin, string>
+    status:            'ready' | 'warning' | 'error'
+    existing:          boolean
+    metadataUrl?:      string
+    createdPostId?:    number
+    importStatus?:     PostImportStatus }
+
+export type PostImportResultRow = {
+    sourceRow: number
+    status:    PostImportResultStatus
+    post?:     { id: number }
+    errors?:   Record<string, string[]> }
+
+export type PostImportSession = {
+    version:    number
+    savedAt:    string
+    source:     string
+    existing:   'skip' | 'error'
+    rows:       PostImportRow[]
+    repairMode: PostImportRepairMode }
+
+const SESSION_VERSION = 1
+const SESSION_PREFIX = 'post-import-session:'
+const SOURCE_DRAFT_KEY = 'post-import-source-draft'
+
+
+export const createPostImportSessionId = (): string =>
+    typeof crypto !== 'undefined' && 'randomUUID' in crypto
+    ? crypto.randomUUID ()
+    : `${ Date.now () }-${ Math.random ().toString (36).slice (2) }`
+
+
+export const loadPostImportSourceDraft = (): {
+    source:   string
+    existing: 'skip' | 'error' } => {
+    if (typeof window === 'undefined')
+      return { source: '', existing: 'skip' }
+
+    try
+    {
+	const raw = sessionStorage.getItem (SOURCE_DRAFT_KEY)
+	if (raw == null)
+	  return { source: '', existing: 'skip' }
+
+	const value = JSON.parse (raw) as {
+	    source?: string
+	    existing?: 'skip' | 'error' }
+	return {
+	    source: typeof value.source === 'string' ? value.source : '',
+	    existing: value.existing === 'error' ? 'error' : 'skip' }
+    }
+    catch
+    {
+	return { source: '', existing: 'skip' }
+    }
+}
+
+
+export const savePostImportSourceDraft = (
+    source:   string,
+    existing: 'skip' | 'error',
+) => {
+    if (typeof window === 'undefined')
+      return
+
+    sessionStorage.setItem (SOURCE_DRAFT_KEY, JSON.stringify ({ source, existing }))
+}
+
+
+const sessionKey = (sessionId: string): string => `${ SESSION_PREFIX }${ sessionId }`
+
+
+export const savePostImportSession = (
+    sessionId: string,
+    session:   Omit<PostImportSession, 'version' | 'savedAt'>,
+) => {
+    if (typeof window === 'undefined')
+      return
+
+    sessionStorage.setItem (sessionKey (sessionId), JSON.stringify ({
+	...session,
+	version: SESSION_VERSION,
+	savedAt: new Date ().toISOString () }))
+}
+
+
+export const loadPostImportSession = (
+    sessionId: string,
+): PostImportSession | null => {
+    if (typeof window === 'undefined')
+      return null
+
+    try
+    {
+	const raw = sessionStorage.getItem (sessionKey (sessionId))
+	if (raw == null)
+	  return null
+
+	const value = JSON.parse (raw) as Partial<PostImportSession>
+	if (value.version !== SESSION_VERSION || !(Array.isArray (value.rows)))
+	  return null
+
+	return {
+	    version: SESSION_VERSION,
+	    savedAt: typeof value.savedAt === 'string' ? value.savedAt : '',
+	    source: typeof value.source === 'string' ? value.source : '',
+	    existing: value.existing === 'error' ? 'error' : 'skip',
+	    rows: value.rows as PostImportRow[],
+	    repairMode: value.repairMode === 'failed' ? 'failed' : 'all' }
+    }
+    catch
+    {
+	return null
+    }
+}
+
+
+export const mergeValidatedImportRows = (
+    current:   PostImportRow[],
+    validated: PostImportRow[],
+): PostImportRow[] =>
+    current
+	.map (previous => {
+	    if (previous.importStatus === 'created')
+	      return previous
+
+	    const row = validated.find (_1 => _1.sourceRow === previous.sourceRow)
+	    return row
+		? {
+		    ...row,
+		    importStatus: previous.importStatus,
+		    createdPostId: previous.createdPostId,
+		    importErrors: previous.importErrors,
+		    validationErrors: row.validationErrors ?? { } }
+		: previous
+	})
+	.concat (validated.filter (row =>
+	    !(current.some (_1 => _1.sourceRow === row.sourceRow))))
+
+
+export const mergeImportResults = (
+    rows:    PostImportRow[],
+    results: PostImportResultRow[],
+): PostImportRow[] =>
+    rows.map (row => {
+	const result = results.find (_1 => _1.sourceRow === row.sourceRow)
+	return result
+	    ? {
+		...row,
+		importStatus: result.status,
+		createdPostId: result.post?.id,
+		importErrors: result.errors,
+		validationErrors: row.validationErrors }
+	    : row
+    })
+
+
+export const retryImportRow = (
+    rows:      PostImportRow[],
+    sourceRow: number,
+): PostImportRow[] =>
+    rows.map (row =>
+	row.sourceRow === sourceRow && row.importStatus === 'failed'
+	? { ...row, importStatus: 'pending', importErrors: undefined }
+	: row)
+
+
+export const rowMessages = (row: PostImportRow): string[] => [
+    ...row.warnings,
+    ...Object.values (row.validationErrors ?? { }).flat (),
+    ...Object.values (row.importErrors ?? { }).flat ()]
+
+
+export const countImportSourceLines = (source: string): number =>
+    source
+	.split (/\r\n|\n|\r/)
+	.map (_1 => _1.trim ())
+	.filter (_1 => _1 !== '')
+	.length
+
+
+export const countImportSourceValidLines = (source: string): number =>
+    source
+	.split (/\r\n|\n|\r/)
+	.map (_1 => _1.trim ())
+	.filter (_1 => /^https?:\/\//.test (_1))
+	.length
+
+
+export const submittableImportRows = (rows: PostImportRow[]): PostImportRow[] =>
+    rows.filter (row => row.importStatus == null || row.importStatus === 'pending')
+
+
+export const reviewSummaryCounts = (rows: PostImportRow[]) => ({
+    total: rows.length,
+    submittable: rows.filter (row =>
+	(row.importStatus == null || row.importStatus === 'pending')
+	&& Object.keys (row.validationErrors ?? { }).length === 0).length,
+    invalid: rows.filter (row => Object.keys (row.validationErrors ?? { }).length > 0).length,
+    skipPlanned: rows.filter (row =>
+	row.existing && row.importStatus !== 'created' && row.status !== 'error').length,
+    created: rows.filter (row => row.importStatus === 'created').length,
+    failed: rows.filter (row => row.importStatus === 'failed').length })

frontend/src/pages/posts/PostImportResultPage.tsx

@@ -0,0 +1,253 @@
+import { useEffect, useMemo, useState } from 'react'
+import { Helmet } from 'react-helmet-async'
+import { useNavigate,
+	 useParams } from 'react-router-dom'
+
+import FieldError from '@/components/common/FieldError'
+import PageTitle from '@/components/common/PageTitle'
+import PrefetchLink from '@/components/PrefetchLink'
+import MainArea from '@/components/layout/MainArea'
+import PostImportStatusBadge from '@/components/posts/import/PostImportStatusBadge'
+import { Button } from '@/components/ui/button'
+import { toast } from '@/components/ui/use-toast'
+import { SITE_TITLE } from '@/config'
+import { apiPost } from '@/lib/api'
+import { canEditContent } from '@/lib/users'
+import { loadPostImportSession,
+	 mergeImportResults,
+	 retryImportRow,
+	 savePostImportSession,
+	 type PostImportResultRow,
+	 type PostImportSession } from '@/lib/postImportSession'
+import Forbidden from '@/pages/Forbidden'
+
+import type { FC } from 'react'
+
+import type { User } from '@/types'
+
+type Props = { user: User | null }
+
+const resultToneClass = (status: string | undefined): string[] => {
+    switch (status)
+      {
+      case 'created':
+	return [
+	    'border-sky-200 bg-sky-50',
+	    'dark:border-sky-900 dark:bg-sky-950/30']
+      case 'skipped':
+	return [
+	    'border-stone-200 bg-stone-50',
+	    'dark:border-stone-800 dark:bg-stone-900/60']
+      case 'failed':
+	return [
+	    'border-rose-200 bg-rose-50',
+	    'dark:border-rose-900 dark:bg-rose-950/30']
+      default:
+	return [
+	    'border-border bg-white',
+	    'dark:border-neutral-700 dark:bg-neutral-900']
+      }
+}
+
+
+const PostImportResultPage: FC<Props> = ({ user }) => {
+    const editable = canEditContent (user)
+    const navigate = useNavigate ()
+    const { sessionId } = useParams ()
+
+    const [session, setSession] = useState<PostImportSession | null> (null)
+    const [missing, setMissing] = useState (false)
+    const [loadingRow, setLoadingRow] = useState<number | null> (null)
+
+    useEffect (() => {
+	if (!(sessionId))
+	  return
+
+	const loaded = loadPostImportSession (sessionId)
+	setSession (loaded)
+	setMissing (loaded == null)
+    }, [sessionId])
+
+    useEffect (() => {
+	if (!(sessionId) || !(session))
+	  return
+
+	savePostImportSession (sessionId, session)
+    }, [session, sessionId])
+
+    const counts = useMemo (() => ({
+	created: session?.rows.filter (_1 => _1.importStatus === 'created').length ?? 0,
+	skipped: session?.rows.filter (_1 => _1.importStatus === 'skipped').length ?? 0,
+	failed: session?.rows.filter (_1 => _1.importStatus === 'failed').length ?? 0 }), [session])
+
+    const retry = async (sourceRow: number) => {
+	if (!(session))
+	  return
+
+	setLoadingRow (sourceRow)
+	try
+	{
+	    const pendingRows = retryImportRow (session.rows, sourceRow)
+	    setSession ({ ...session, rows: pendingRows })
+	    const target = pendingRows.find (_1 => _1.sourceRow === sourceRow)
+	    if (target == null)
+	      return
+
+	    const result = await apiPost<{
+		created: number
+		skipped: number
+		failed:  number
+		rows:    PostImportResultRow[] }> ('/posts/import', {
+		    rows: [{
+			sourceRow: target.sourceRow,
+			url: target.url,
+			attributes: target.attributes,
+			provenance: target.provenance,
+			tagSources: target.tagSources,
+			metadataUrl: target.metadataUrl }],
+		    existing: session.existing })
+	    setSession (current =>
+		current
+		? { ...current, rows: mergeImportResults (current.rows, result.rows) }
+		: current)
+	}
+	catch
+	{
+	    setSession (session)
+	    toast ({ title: '再試行に失敗しました' })
+	}
+	finally
+	{
+	    setLoadingRow (null)
+	}
+    }
+
+    const openRepair = (sourceRow: number) => {
+	const nextSession = { ...session, repairMode: 'failed' as const }
+	setSession (nextSession)
+	if (sessionId)
+	  savePostImportSession (sessionId, nextSession)
+	navigate (`/posts/import/${ sessionId }/review?edit=${ sourceRow }`)
+    }
+
+    if (!(editable))
+      return <Forbidden/>
+
+    if (missing || !(sessionId) || !(session))
+      {
+	return (
+	    <MainArea>
+	      <div className="mx-auto max-w-4xl space-y-4 p-4">
+		<PageTitle>投稿インポート結果</PageTitle>
+		<FieldError messages={['取込状態が見つかりません．']}/>
+		<Button type="button" onClick={() => navigate ('/posts/import')}>
+		  URL リスト入力へ戻る
+		</Button>
+	      </div>
+	    </MainArea>)
+      }
+
+    return (
+	<MainArea>
+	  <Helmet>
+	    <title>{`投稿インポート結果 | ${ SITE_TITLE }`}</title>
+	  </Helmet>
+
+	  <div className="mx-auto max-w-5xl space-y-4 p-4">
+	    <PageTitle>登録結果</PageTitle>
+
+	    <div className="rounded-lg border bg-white p-4 dark:border-neutral-700
+			    dark:bg-neutral-900">
+	      <div className="flex flex-wrap gap-2">
+		<SummaryChip label="登録成功" value={counts.created} badge="created"/>
+		<SummaryChip label="スキップ" value={counts.skipped} badge="skipped"/>
+		<SummaryChip label="失敗" value={counts.failed} badge="failed"/>
+	      </div>
+	    </div>
+
+	    <div className="space-y-3">
+	      {session.rows.map (row => (
+		  <div
+		      key={row.sourceRow}
+		      className={[
+			  'rounded-lg border p-4',
+			  ...resultToneClass (row.importStatus)].join (' ')}>
+		    <div className="flex flex-col gap-3 md:flex-row md:items-start
+				    md:justify-between">
+		      <div className="space-y-2">
+			<div className="flex flex-wrap items-center gap-2">
+			  <span className="text-sm font-medium">行 {row.sourceRow}</span>
+			  <PostImportStatusBadge value={row.importStatus ?? 'pending'}/>
+			</div>
+			<div className="text-sm text-neutral-700 dark:text-neutral-200">
+			  {String (row.attributes.title ?? '') || row.url}
+			</div>
+			<div className="text-xs text-neutral-500 dark:text-neutral-400">
+			  {row.url}
+			</div>
+			<FieldError messages={Object.values (row.importErrors ?? { }).flat ()}/>
+		      </div>
+
+		      <div className="flex flex-col gap-2 sm:flex-row">
+			{row.createdPostId && (
+			    <Button type="button" variant="outline" asChild>
+			      <PrefetchLink to={`/posts/${ row.createdPostId }`}>
+				投稿を開く
+			      </PrefetchLink>
+			    </Button>)}
+			{row.importStatus === 'failed' && (
+			    <>
+			      <Button
+				  type="button"
+				  variant="outline"
+				  onClick={() => openRepair (row.sourceRow)}>
+				修正
+			      </Button>
+			      <Button
+				  type="button"
+				  onClick={() => retry (row.sourceRow)}
+				  disabled={loadingRow === row.sourceRow}>
+				再試行
+			      </Button>
+			    </>)}
+		      </div>
+		    </div>
+		  </div>))}
+	    </div>
+
+	    <div className="flex flex-col gap-2 sm:flex-row">
+	      <Button
+		  type="button"
+		  variant="outline"
+		  onClick={() => {
+		      const nextSession = { ...session, repairMode: 'all' as const }
+		      setSession (nextSession)
+		      savePostImportSession (sessionId, nextSession)
+		      navigate (`/posts/import/${ sessionId }/review`)
+		  }}>
+		確認画面へ戻る
+	      </Button>
+	      <Button
+		  type="button"
+		  variant="outline"
+		  onClick={() => navigate ('/posts/import')}>
+		新しい URL リストを入力
+	      </Button>
+	    </div>
+	  </div>
+	</MainArea>)
+}
+
+const SummaryChip = (
+    { label, value, badge }: {
+	label: string
+	value: number
+	badge: 'created' | 'skipped' | 'failed' },
+) => (
+    <div className="flex items-center gap-2 rounded-full border border-border
+		    bg-background px-3 py-1 text-sm">
+      <PostImportStatusBadge value={badge}/>
+      <span>{label} {value}</span>
+    </div>)
+
+export default PostImportResultPage

frontend/src/pages/posts/PostImportReviewPage.tsx

@@ -0,0 +1,363 @@
+import { useEffect, useMemo, useState } from 'react'
+import { Helmet } from 'react-helmet-async'
+import { useNavigate,
+	 useParams,
+	 useSearchParams } from 'react-router-dom'
+
+import FieldError from '@/components/common/FieldError'
+import PageTitle from '@/components/common/PageTitle'
+import MainArea from '@/components/layout/MainArea'
+import PostImportRowDialog from '@/components/posts/import/PostImportRowDialog'
+import PostImportRowSummary from '@/components/posts/import/PostImportRowSummary'
+import PostImportStatusBadge from '@/components/posts/import/PostImportStatusBadge'
+import { Button } from '@/components/ui/button'
+import { toast } from '@/components/ui/use-toast'
+import { SITE_TITLE } from '@/config'
+import { apiPost } from '@/lib/api'
+import { canEditContent } from '@/lib/users'
+import { loadPostImportSession,
+	 mergeImportResults,
+	 mergeValidatedImportRows,
+	 reviewSummaryCounts,
+	 rowMessages,
+	 savePostImportSession,
+	 submittableImportRows,
+	 type PostImportResultRow,
+	 type PostImportRow,
+	 type PostImportSession } from '@/lib/postImportSession'
+import Forbidden from '@/pages/Forbidden'
+
+import type { FC } from 'react'
+
+import type { User } from '@/types'
+
+type Props = { user: User | null }
+
+type Draft = {
+    url:                   string
+    title:                 string
+    thumbnailBase:         string
+    originalCreatedFrom:   string
+    originalCreatedBefore: string
+    duration:              string
+    tags:                  string
+    parentPostIds:         string }
+
+
+const PostImportReviewPage: FC<Props> = ({ user }) => {
+    const editable = canEditContent (user)
+    const navigate = useNavigate ()
+    const { sessionId } = useParams ()
+    const [searchParams, setSearchParams] = useSearchParams ()
+
+    const [session, setSession] = useState<PostImportSession | null> (null)
+    const [loading, setLoading] = useState (false)
+    const [missing, setMissing] = useState (false)
+    const [savingRow, setSavingRow] = useState<number | null> (null)
+
+    useEffect (() => {
+	if (!(sessionId))
+	  return
+
+	const loaded = loadPostImportSession (sessionId)
+	setSession (loaded)
+	setMissing (loaded == null)
+    }, [sessionId])
+
+    useEffect (() => {
+	if (!(sessionId) || !(session))
+	  return
+
+	savePostImportSession (sessionId, session)
+    }, [session, sessionId])
+
+    const rows = session?.rows ?? []
+    const editingSourceRow = Number (searchParams.get ('edit') ?? '')
+    const editingRow =
+	Number.isFinite (editingSourceRow)
+	? rows.find (_1 => _1.sourceRow === editingSourceRow) ?? null
+	: null
+    const counts = useMemo (() => reviewSummaryCounts (rows), [rows])
+    const submittable = useMemo (
+	() => submittableImportRows (rows).filter (row =>
+	    Object.keys (row.validationErrors ?? { }).length === 0),
+	[rows],
+    )
+    const reviewRows =
+	session?.repairMode === 'failed'
+	? [...rows].sort ((a, b) => {
+	    const aFailed = a.importStatus === 'failed' ? 0 : 1
+	    const bFailed = b.importStatus === 'failed' ? 0 : 1
+	    return aFailed - bFailed || a.sourceRow - b.sourceRow
+	})
+	: rows
+
+    useEffect (() => {
+	if (editingRow == null || session?.repairMode !== 'failed')
+	  return
+
+	const element = document.getElementById (`post-import-row-${ editingRow.sourceRow }`)
+	element?.scrollIntoView ({ block: 'center', behaviour: 'smooth' })
+    }, [editingRow, session?.repairMode])
+
+    const updateSessionRows = (nextRows: PostImportRow[]) =>
+	setSession (current =>
+	    current ? { ...current, rows: nextRows } : current)
+
+    const saveDraft = async (draft: Draft): Promise<boolean> => {
+	if (!(session))
+	  return false
+	if (editingRow == null)
+	  return false
+
+	const urlChanged = draft.url !== editingRow.url
+	const nextProvenance = { ...editingRow.provenance }
+	const nextAttributes = { ...editingRow.attributes }
+	const nextTagSources = {
+	    automatic: editingRow.tagSources?.automatic ?? '',
+	    manual: editingRow.tagSources?.manual ?? '' }
+	const draftFields = [
+	    ['title', draft.title],
+	    ['thumbnailBase', draft.thumbnailBase],
+	    ['originalCreatedFrom', draft.originalCreatedFrom],
+	    ['originalCreatedBefore', draft.originalCreatedBefore],
+	    ['duration', draft.duration],
+	    ['parentPostIds', draft.parentPostIds],
+	] as const
+	draftFields.forEach (([field, value]) => {
+	    nextAttributes[field] = value
+	    nextProvenance[field] =
+		value !== String (editingRow.attributes[field] ?? '')
+		? 'manual'
+		: (editingRow.provenance[field] ?? 'automatic')
+	})
+	nextAttributes.tags = draft.tags
+	if (draft.tags !== String (editingRow.attributes.tags ?? ''))
+	  {
+	    nextProvenance.tags = 'manual'
+	    nextTagSources.manual = draft.tags
+	  }
+	else
+	  {
+	    nextProvenance.tags = editingRow.provenance.tags ?? 'automatic'
+	    nextTagSources.manual = editingRow.tagSources?.manual ?? ''
+	  }
+
+	setSavingRow (editingRow.sourceRow)
+	const nextRows = session.rows.map (row =>
+	    row.sourceRow === editingRow.sourceRow
+	    ? {
+		...row,
+		url: draft.url,
+		attributes: nextAttributes,
+		provenance: {
+		    ...nextProvenance,
+		    url: urlChanged ? 'manual' : (editingRow.provenance.url ?? 'manual') },
+		tagSources: nextTagSources,
+		importStatus: row.importStatus === 'created' ? 'created' : 'pending',
+		importErrors: undefined }
+	    : row)
+	try
+	{
+	    const validated = await apiPost<{ rows: PostImportRow[] }> ('/posts/import/validate', {
+		rows: nextRows.filter (row => row.importStatus !== 'created'),
+		existing: session.existing,
+		changed_row: urlChanged ? editingRow.sourceRow : -1 })
+	    updateSessionRows (mergeValidatedImportRows (nextRows, validated.rows))
+	    setSearchParams ({ })
+	    return true
+	}
+	catch
+	{
+	    toast ({ title: '行の再検証に失敗しました' })
+	    return false
+	}
+	finally
+	{
+	    setSavingRow (null)
+	}
+    }
+
+    const updateExisting = async (value: 'skip' | 'error') => {
+	if (!(session))
+	  return
+
+	const pendingRows = session.rows.map (row =>
+	    row.importStatus === 'created'
+	    ? row
+	    : {
+		...row,
+		importStatus: 'pending' as const,
+		importErrors: undefined })
+	setSession ({ ...session, existing: value, rows: pendingRows })
+	setLoading (true)
+	try
+	{
+	    const validated = await apiPost<{ rows: PostImportRow[] }> ('/posts/import/validate', {
+		rows: pendingRows.filter (row => row.importStatus !== 'created'),
+		existing: value,
+		changed_row: -1 })
+	    updateSessionRows (mergeValidatedImportRows (pendingRows, validated.rows))
+	}
+	finally
+	{
+	    setLoading (false)
+	}
+    }
+
+    const submit = async () => {
+	if (!(sessionId) || !(session) || submittable.length === 0)
+	  return
+
+	setLoading (true)
+	try
+	{
+	    const result = await apiPost<{
+		created: number
+		skipped: number
+		failed:  number
+		rows:    PostImportResultRow[] }> ('/posts/import', {
+		    rows: submittable.map (row => ({
+			sourceRow: row.sourceRow,
+			url: row.url,
+			attributes: row.attributes,
+			provenance: row.provenance,
+			tagSources: row.tagSources,
+			metadataUrl: row.metadataUrl })),
+		    existing: session.existing })
+	    const nextRows = mergeImportResults (session.rows, result.rows)
+	    const nextSession = { ...session, rows: nextRows, repairMode: 'all' as const }
+	    setSession (nextSession)
+	    savePostImportSession (sessionId, nextSession)
+	    navigate (`/posts/import/${ sessionId }/result`)
+	}
+	catch
+	{
+	    toast ({ title: '登録に失敗しました' })
+	}
+	finally
+	{
+	    setLoading (false)
+	}
+    }
+
+    if (!(editable))
+      return <Forbidden/>
+
+    if (missing || !(sessionId) || !(session))
+      {
+	return (
+	    <MainArea>
+	      <div className="mx-auto max-w-4xl space-y-4 p-4">
+		<PageTitle>投稿インポート</PageTitle>
+		<FieldError messages={['取込状態が見つかりません．']}/>
+		<Button type="button" onClick={() => navigate ('/posts/import')}>
+		  URL リスト入力へ戻る
+		</Button>
+	      </div>
+	    </MainArea>)
+      }
+
+    return (
+	<MainArea>
+	  <Helmet>
+	    <title>{`投稿インポート確認 | ${ SITE_TITLE }`}</title>
+	  </Helmet>
+
+	  <div className="mx-auto max-w-6xl space-y-4 p-4 pb-28">
+	    <PageTitle>投稿情報の確認</PageTitle>
+
+	    <div className="rounded-lg border bg-white p-4 dark:border-neutral-700
+			    dark:bg-neutral-900">
+	      <div className="flex flex-wrap items-center gap-2">
+		<SummaryChip label="全件" value={counts.total}/>
+		<SummaryChip label="登録対象" value={counts.submittable}/>
+		<SummaryChip label="要修正" value={counts.invalid}/>
+		<SummaryChip label="スキップ予定" value={counts.skipPlanned}/>
+		<SummaryChip label="登録済み" value={counts.created}/>
+		<SummaryChip label="失敗" value={counts.failed}/>
+	      </div>
+	    </div>
+
+	    <div className="rounded-lg border bg-white p-4 dark:border-neutral-700
+			    dark:bg-neutral-900">
+	      <div className="flex flex-wrap items-center justify-between gap-3">
+		<div className="text-sm text-neutral-600 dark:text-neutral-300">
+		  URL {rows.length} 件
+		</div>
+		<label className="flex items-center gap-2 text-sm">
+		  <span>既存投稿</span>
+		  <select
+		      value={session.existing}
+		      onChange={ev => updateExisting (ev.target.value as 'skip' | 'error')}
+		      className="rounded border border-border bg-background px-3 py-2">
+		    <option value="skip">スキップ</option>
+		    <option value="error">エラー</option>
+		  </select>
+		</label>
+	      </div>
+	    </div>
+
+	    <div className="space-y-3">
+	      {reviewRows.map (row => (
+		  <div key={row.sourceRow} id={`post-import-row-${ row.sourceRow }`}>
+		    <PostImportRowSummary
+			row={row}
+			onEdit={() => {
+			    setSearchParams ({ edit: String (row.sourceRow) })
+			}}/>
+		    {rowMessages (row).length > 0 && (
+			<div className="mt-2 md:max-w-3xl">
+			  <FieldError messages={rowMessages (row)}/>
+			</div>)}
+		  </div>))}
+	    </div>
+	  </div>
+
+	  <div
+	      className="fixed inset-x-0 bottom-0 border-t bg-white/95 p-4 backdrop-blur
+			 dark:border-neutral-700 dark:bg-neutral-950/95">
+	    <div className="mx-auto flex max-w-6xl flex-col gap-3 md:flex-row
+			    md:items-center md:justify-between">
+	      <div className="flex flex-wrap items-center gap-2 text-sm">
+		<PostImportStatusBadge value="pending"/>
+		<span>登録対象 {submittable.length} 件</span>
+		<PostImportStatusBadge value="error"/>
+		<span>要修正 {counts.invalid} 件</span>
+	      </div>
+	      <div className="flex flex-col gap-2 sm:flex-row">
+		<Button
+		    type="button"
+		    variant="outline"
+		    onClick={() => navigate ('/posts/import')}>
+		  URL リスト入力へ戻る
+		</Button>
+		<Button
+		    type="button"
+		    onClick={submit}
+		    disabled={loading || submittable.length === 0}>
+		  有効な投稿を一括登録
+		</Button>
+	      </div>
+	    </div>
+	  </div>
+
+	  <PostImportRowDialog
+	      open={editingRow != null}
+	      row={editingRow}
+	      saving={savingRow != null}
+	      onOpenChange={open => {
+		  if (!(open))
+		    setSearchParams ({ })
+	      }}
+	      onSave={saveDraft}/>
+	</MainArea>)
+}
+
+const SummaryChip = ({ label, value }: { label: string
+					  value: number }) => (
+    <div className="rounded-full border border-border bg-background px-3 py-1 text-sm">
+      {label} {value}
+    </div>)
+
+export default PostImportReviewPage

frontend/src/pages/posts/PostImportSourcePage.tsx

@@ -0,0 +1,153 @@
+import { useEffect, useMemo, useState } from 'react'
+import { Helmet } from 'react-helmet-async'
+import { useNavigate } from 'react-router-dom'
+
+import FieldError from '@/components/common/FieldError'
+import FormField from '@/components/common/FormField'
+import PageTitle from '@/components/common/PageTitle'
+import MainArea from '@/components/layout/MainArea'
+import { Button } from '@/components/ui/button'
+import { toast } from '@/components/ui/use-toast'
+import { SITE_TITLE } from '@/config'
+import { apiPost, isApiError } from '@/lib/api'
+import { canEditContent } from '@/lib/users'
+import { inputClass } from '@/lib/utils'
+import { countImportSourceLines,
+	 countImportSourceValidLines,
+	 createPostImportSessionId,
+	 loadPostImportSourceDraft,
+	 savePostImportSession,
+	 savePostImportSourceDraft,
+	 type PostImportRow } from '@/lib/postImportSession'
+import Forbidden from '@/pages/Forbidden'
+
+import type { FC } from 'react'
+
+import type { User } from '@/types'
+
+type Props = { user: User | null }
+
+const MAX_ROWS = 100
+
+
+const PostImportSourcePage: FC<Props> = ({ user }) => {
+    const editable = canEditContent (user)
+    const navigate = useNavigate ()
+    const draft = useMemo (() => loadPostImportSourceDraft (), [])
+
+    const [source, setSource] = useState (draft.source)
+    const [existing, setExisting] = useState<'skip' | 'error'> (draft.existing)
+    const [loading, setLoading] = useState (false)
+    const [error, setError] = useState<string | null> (null)
+
+    const lineCount = countImportSourceLines (source)
+    const validLineCount = countImportSourceValidLines (source)
+    const messages = [
+	...(lineCount === 0 ? ['URL を入力してください．'] : []),
+	...(lineCount > MAX_ROWS ? [`最大 ${ MAX_ROWS } 件までです．`] : []),
+	...(error ? [error] : [])]
+
+    useEffect (() => {
+	savePostImportSourceDraft (source, existing)
+    }, [existing, source])
+
+    const preview = async () => {
+	setLoading (true)
+	setError (null)
+	try
+	{
+	    const data = await apiPost<{ rows: PostImportRow[] }> ('/posts/import/preview', {
+		source,
+		existing })
+	    const sessionId = createPostImportSessionId ()
+	    savePostImportSession (sessionId, {
+		source,
+		existing,
+		rows: data.rows,
+		repairMode: 'all' })
+	    navigate (`/posts/import/${ sessionId }/review`)
+	}
+	catch (requestError)
+	{
+	    const message =
+		isApiError<{ message?: string, baseErrors?: string[] }> (requestError)
+		? requestError.response?.data?.message
+		    ?? requestError.response?.data?.baseErrors?.[0]
+		: undefined
+	    setError (message ?? '入力を確認してください．')
+	    toast ({
+		title: '投稿情報の取得に失敗しました',
+		description: message ?? '入力を確認してください．' })
+	}
+	finally
+	{
+	    setLoading (false)
+	}
+    }
+
+    if (!(editable))
+      return <Forbidden/>
+
+    return (
+	<MainArea>
+	  <Helmet>
+	    <title>{`投稿インポート | ${ SITE_TITLE }`}</title>
+	  </Helmet>
+
+	  <div className="mx-auto max-w-4xl space-y-4 p-4">
+	    <PageTitle>投稿インポート</PageTitle>
+	    <div className="rounded-lg border bg-white p-4 dark:border-neutral-700
+			    dark:bg-neutral-900 md:p-6">
+	      <div className="space-y-4">
+		<div className="space-y-2">
+		  <h2 className="text-lg font-semibold">URL リストを入力</h2>
+		  <p className="text-sm text-neutral-600 dark:text-neutral-300">
+		    一行につき一つの URL を入力してください．
+		  </p>
+		</div>
+
+		<FormField label="URL リスト">
+		  {() => (
+		      <textarea
+			  value={source}
+			  rows={14}
+			  className={inputClass (
+			      messages.length > 0,
+			      'font-mono text-sm',
+			  )}
+			  onChange={ev => setSource (ev.target.value)}/>)}
+		</FormField>
+		<FieldError messages={messages}/>
+
+		<div className="flex flex-wrap items-center justify-between gap-3 text-sm
+				text-neutral-600 dark:text-neutral-300">
+		  <div>有効行数: {validLineCount}</div>
+		  <div>最大 {MAX_ROWS} 件</div>
+		</div>
+
+		<label className="block space-y-1">
+		  <span className="text-sm font-medium">既存投稿</span>
+		  <select
+		      value={existing}
+		      onChange={ev => setExisting (ev.target.value as typeof existing)}
+		      className={inputClass (false, 'w-full md:w-auto')}>
+		    <option value="skip">スキップ</option>
+		    <option value="error">エラー</option>
+		  </select>
+		</label>
+
+		<div className="flex justify-end">
+		  <Button
+		      type="button"
+		      onClick={preview}
+		      disabled={loading || lineCount === 0 || lineCount > MAX_ROWS}>
+		    投稿情報を取得
+		  </Button>
+		</div>
+	      </div>
+	    </div>
+	  </div>
+	</MainArea>)
+}
+
+export default PostImportSourcePage

frontend/src/pages/posts/PostNewPage.tsx

@@ -25,7 +25,13 @@ import type { User } from '@/types'
 type Props = { user: User | null }
 
 type PostFormField =
-    'url' | 'title' | 'tags' | 'parentPostIds' | 'videoMs' | 'originalCreatedAt' | 'thumbnail'
+    'url'
+    | 'title'
+    | 'tags'
+    | 'parentPostIds'
+    | 'videoMs'
+    | 'originalCreatedAt'
+    | 'thumbnail'
 
 
 const PostNewPage: FC<Props> = ({ user }) => {
@@ -36,8 +42,10 @@ const PostNewPage: FC<Props> = ({ user }) => {
   const { baseErrors, fieldErrors, clearValidationErrors, applyValidationError } =
       useValidationErrors<PostFormField> ()
 
-  const [originalCreatedBefore, setOriginalCreatedBefore] = useState<string | null> (null)
+  const [originalCreatedBefore, setOriginalCreatedBefore] =
-  const [originalCreatedFrom, setOriginalCreatedFrom] = useState<string | null> (null)
+      useState<string | null> (null)
+  const [originalCreatedFrom, setOriginalCreatedFrom] =
+      useState<string | null> (null)
   const [parentPostIds, setParentPostIds] = useState ('')
   const [tags, setTags] = useState ('')
   const [duration, setDuration] = useState ('')
@@ -50,8 +58,10 @@ const PostNewPage: FC<Props> = ({ user }) => {
 
   const thumbnailPreviewRef = useRef ('')
   const videoFlg =
-      useMemo (() => tags.split (/\s+/).some (tag => tag.replace (/\[.*\]$/, '') === '動画'),
+      useMemo (() =>
-               [tags])
+	  tags.split (/\s+/).some (
+	      tag => tag.replace (/\[.*\]$/, '') === '動画'),
+	       [tags])
 
   const handleSubmit = async () => {
     clearValidationErrors ()
@@ -72,14 +82,15 @@ const PostNewPage: FC<Props> = ({ user }) => {
 
     try
     {
-      await apiPost ('/posts', formData, { headers: { 'Content-Type': 'multipart/form-data' } })
+      await apiPost ('/posts', formData,
+		     { headers: { 'Content-Type': 'multipart/form-data' } })
       toast ({ title: '投稿成功!' })
       navigate ('/posts')
     }
     catch (e)
     {
       applyValidationError (e)
-      toast ({ title: '投稿失敗', description: '入力を確認してください。' })
+      toast ({ title: '投稿失敗', description: '入力を確認してください．' })
     }
   }
 
@@ -87,7 +98,8 @@ const PostNewPage: FC<Props> = ({ user }) => {
     setTitleLoading (true)
     try
     {
-      const data = await apiGet<{ title: string }> ('/preview/title', { params: { url } })
+      const data = await apiGet<{ title: string }> ('/preview/title',
+						    { params: { url } })
       setTitle (data.title || '')
     }
     finally
@@ -105,7 +117,8 @@ const PostNewPage: FC<Props> = ({ user }) => {
     try
     {
       const data = await apiGet<Blob> ('/preview/thumbnail',
-				       { params: { url }, responseType: 'blob' })
+				       { params: { url },
+					 responseType: 'blob' })
       const imageURL = URL.createObjectURL (data)
       setThumbnailPreview (imageURL)
       setThumbnailFile (new File ([data],
@@ -163,7 +176,7 @@ const PostNewPage: FC<Props> = ({ user }) => {
 		    <Button
 			type="button"
 			variant="outline"
-			onClick={() => void fetchTitle ()}
+			onClick={fetchTitle}
 			disabled={!(url) || titleLoading}>
 		      取得
 		    </Button>
@@ -180,7 +193,7 @@ const PostNewPage: FC<Props> = ({ user }) => {
 		    <Button
 			type="button"
 			variant="outline"
-			onClick={() => void fetchThumbnail ()}
+			onClick={fetchThumbnail}
 			disabled={!(url) || thumbnailLoading}>
 		      取得
 		    </Button>