#383

開発環境では、**DB を壊さない前提で、migration → API → 画面 → 同期 → ZIP → 履歴**の順に見るのがよいです。今回の差分は素材管理全体に触っているので、単体でチョンチョン見るより、素材の一生を通すのが早いです。

## 0. 先に方針

**やらないこと:**

```sh id="snb3i6"
rails db:drop
rails db:reset
rails db:setup
DISABLE_DATABASE_ENVIRONMENT_CHECK=1 ...
```

これは禁止。
開発 DB に本番データを入れているなら、床板を剥がして耐震確認するようなものです。

---

## 1. migration 確認

まず現在の状態を見る。

```sh id="qsdfpt"
cd backend
RAILS_ENV=development bundle exec rails db:migrate:status
```

その後、通常 migration。

```sh id="a89fir"
RAILS_ENV=development bundle exec rails db:migrate
```

見るポイント:

```txt id="c1u57a"
materials に source_* / normalized_source_key / version_no がある
material_versions に event_type / file snapshot / source snapshot がある
material_export_items がある
material_sync_suppressions がある
material_sync_sources がある
既存 materials に material_versions version_no=1 create が backfill されている
```

確認用:

```sh id="g4vd4m"
RAILS_ENV=development bundle exec rails runner '
puts "materials=#{Material.count}"
puts "versions=#{MaterialVersion.count}"
puts "materials without versions=#{Material.left_joins(:material_versions).where(material_versions: { id: nil }).count}"
puts "sync suppressions table=#{ActiveRecord::Base.connection.table_exists?(:material_sync_suppressions)}"
'
```

ここで `materials without versions=0` になれば、backfill は通っています。

---

## 2. 既存素材一覧の画面確認

フロントを起動して `/materials` を見る。

```sh id="vl28jd"
cd frontend
npm run dev
```

見る観点:

```txt id="i2ovxw"
初期表示で素材が出る
初期表示ではグルーピングがオフ
タグなし素材も出る
カード表示でサムネまたは代替テキストが出る
一覧表示に切り替えられる
q / tag_state / media_kind / sort / direction が効く
```

ここでまず、普通の素材一覧が壊れていないことを確認します。

---

## 3. 左タグバーの確認

`/materials` を開いて左タグバーからタグを選ぶ。

見る観点:

```txt id="n6udul"
URL が tag_id=...&include_descendants=1&group_by=parent_tag になる
選択中タグが左バーで強調される
一覧上部に「選択中」の表示が出る
「タグ選択を解除」で通常表示に戻れる
解除後、tag_id / include_descendants / group_by / page が消える
子タグ・孫タグの素材も一覧に出る
親タググルーピングされる
```

特に重要なのはこれ。

```txt id="d33os0"
親タグ A を選択
  A に直接紐づく素材
  A > B に紐づく素材
  A > B > C に紐づく素材
が同じ一覧に出ること
```

---

## 4. 選択タグから素材追加

左タグからタグを選択した状態で、一覧上部の **このタグに素材を追加** を押す。

見る観点:

```txt id="qdd5uw"
素材追加画面の tag 欄に選択中タグ名が初期入力されている
file または url を指定して保存できる
保存後 return_to で元のタグ選択済み一覧に戻る
戻った一覧に追加した素材が出る
material_versions に create が 1 件できる
```

Rails console でも確認できます。

```sh id="i07rrb"
RAILS_ENV=development bundle exec rails runner '
m = Material.order(id: :desc).first
puts({ id: m.id, tag: m.tag&.name, versions: m.material_versions.count, version_no: m.version_no }.inspect)
'
```

---

## 5. グループ見出しから素材追加

親タググルーピング表示中に、各グループ見出しの **このタグに素材を追加** を押す。

見る観点:

```txt id="fpx8w4"
グループタグ名が tag 欄に初期入力される
保存後、元の一覧に戻る
追加素材がそのグループ内に出る
```

ここは今回の導線の肝です。棚の見出しから直接その棚へ素材を置けるかを見る。

---

## 6. 素材更新と履歴

既存素材の詳細または編集導線から、タグ・URL・ファイル・export path を更新する。

見る観点:

```txt id="w36i61"
更新前 snapshot が無ければ create が補われる
更新後 update version ができる
file_blob_id / file_filename / file_sha256 が material_versions に入る
export_paths_json が履歴に残る
/materials/changes または /materials/versions で履歴が見える
```

console:

```sh id="a3okhv"
RAILS_ENV=development bundle exec rails runner '
m = Material.order(updated_at: :desc).first
puts m.material_versions.order(:version_no).map { |v|
  [v.version_no, v.event_type, v.tag_name, v.file_filename, v.file_sha256, v.export_paths_hash]
}.inspect
'
```

---

## 7. サムネイル

画像素材を追加して、一覧にサムネイルが出るか確認。

動画素材があるなら、`ffmpeg` が入っている環境で backfill。

```sh id="qxm8fj"
cd backend
RAILS_ENV=development bundle exec rails materials:thumbnails:backfill
```

見る観点:

```txt id="s9a1vf"
画像は 180x180 のサムネが付く
動画はフレームからサムネが作られる
非対応ファイルは代替テキスト表示になる
ログに result が出る
```

---

## 8. ZIP export

export path がある素材を用意して、ブラウザで確認。

```txt id="aq7f7o"
/materials/download.zip?profile=legacy_drive
```

見る観点:

```txt id="h4rve5"
ZIP が落ちる
entry path が material_export_items.export_path になる
disabled な export item は入らない
ファイル実体が欠けている場合は 422 と missing_files が返る
```

---

## 9. 抑止

`/materials/suppressions` で path prefix 抑止を追加する。

見る観点:

```txt id="w80jbu"
member で作成できる
guest は forbidden / unauthorized
google_drive_path_prefix で既存素材が discard される
discard 履歴が material_versions に残る
同期時に同じ source_path 配下が再作成されない
```

---

## 10. Google Drive 同期

開発環境では、まず小さいフォルダでやるのがよいです。
いきなり本番素材集フォルダを食わせると、ログが藪になります 🌿

必要な ENV:

```sh id="kzbb7f"
GOOGLE_DRIVE_SERVICE_ACCOUNT_EMAIL=...
GOOGLE_DRIVE_PRIVATE_KEY_PATH=...
MATERIAL_SYNC_SOURCE_KIND=google_drive_path
MATERIAL_SYNC_SOURCE_FILE_ID=<folder_id>
MATERIAL_SYNC_SOURCE_NAME=dev-small-folder
MATERIAL_SYNC_SOURCE_PROFILE=legacy_drive
```

seed で source 作成、または console で作成。

```sh id="sec40c"
RAILS_ENV=development bundle exec rails db:seed
RAILS_ENV=development bundle exec rails materials:sync
```

見る観点:

```txt id="a5ltqu"
imported / updated / unchanged / suppressed / failed がログに出る
2 回目実行で unchanged が増える
tag は nil のままでも保存できる
人手で tag / url を付けた既存同期素材が、再同期で消えない
Google native file は skip される
download 後 sha256 block が効く
```

---

## 11. schema.rb は別途確認

これはテストというより merge gate です。
今回まだ怪しいので、差分に以下が混ざっていないことを確認します。

```txt id="s3k6da"
wiki_assets 削除
wiki_pages.next_asset_no 削除
素材管理と無関係な CHECK constraint 削除
素材管理と無関係な index order 消失
```

ここが残るなら、機能テストが通っても merge は止めた方がいいです。

---

## 最小テスト順

時間がないなら、この順で十分です。

```txt id="c1k2pw"
1. db:migrate
2. materials without versions = 0 を確認
3. /materials 初期表示
4. 左タグ選択 → 子孫込み表示 → グルーピング
5. タグ選択解除
6. 選択タグから素材追加 → return_to で戻る
7. グループ見出しから素材追加
8. 更新して material_versions を確認
9. ZIP export
10. 小さい Drive folder で materials:sync を 2 回
```

これで、今回の差分の主要な導線はほぼ踏めます。

Reviewed-on: #381
Co-authored-by: miteruzo <miteruzo@naver.com>
Co-committed-by: miteruzo <miteruzo@naver.com>

AGENTS.md

@@ -271,7 +271,12 @@ const value =
 - In TypeScript and TSX, convert every leading run of 8 spaces to a tab
   character.
 - A leading tab is exactly equivalent to 8 leading spaces.
-- Never place a closing parenthesis at the beginning of a line.
+- In TypeScript and TSX function declarations, including `const` arrow
+  function declarations, when the parameter list spans multiple lines, always
+  put the closing parenthesis at the beginning of its own line before the return
+  type or `=>`.
+- In TypeScript and TSX, never place a closing parenthesis at the beginning of
+  a line except for a multi-line function declaration parameter list.
 - Never place a closing square bracket at the beginning of a line.
 - For object literals and other associative-array-style braces, do not place
   the closing brace at the beginning of a line. Function, lambda, callback, and

backend/app/controllers/material_versions_controller.rb

@@ -35,6 +35,11 @@ class MaterialVersionsController < ApplicationController
         tag_name: row.tag_name,
         tag_category: row.tag_category,
         url: row.url,
+        source_kind: row.source_kind,
+        source_uri: row.source_uri,
+        source_path: row.source_path,
+        source_file_id: row.source_file_id,
+        normalized_source_key: row.normalized_source_key,
         file_blob_id: row.file_blob_id,
         file_filename: row.file_filename,
         file_content_type: row.file_content_type,

backend/app/controllers/materials_controller.rb

@@ -1,3 +1,6 @@
+require 'set'
+
+
 class MaterialsController < ApplicationController
   rescue_from MaterialZipExporter::EmptyExportError, with: :render_zip_empty
   rescue_from MaterialZipExporter::DuplicatePathError, with: :render_zip_duplicate_path
@@ -13,12 +16,14 @@ class MaterialsController < ApplicationController
     offset = (page - 1) * limit
 
     filters = material_index_filters
+    tag_graph = material_index_tag_graph(filters)
     q = Material.includes(:material_export_items,
                           thumbnail_attachment: :blob,
                           file_attachment: :blob,
                           tag: :tag_name)
     q = q.where(tag_id: nil) if filters[:tag_state] == 'untagged'
     q = q.where.not(tag_id: nil) if filters[:tag_state] == 'tagged'
+    q = apply_material_tag_filter(q, filters, tag_graph)
     q = q.where('materials.created_at >= ?', filters[:created_from]) if filters[:created_from]
     q = q.where('materials.created_at <= ?', filters[:created_to]) if filters[:created_to]
     q = q.where('materials.updated_at >= ?', filters[:updated_from]) if filters[:updated_from]
@@ -37,8 +42,16 @@ class MaterialsController < ApplicationController
         .offset(offset)
         .to_a
 
-    render json: { materials: MaterialRepr.list_many(materials, host: request.base_url),
+    response = { materials: MaterialRepr.list_many(materials, host: request.base_url),
-                   count: }
+                 count: }
+    if filters[:tag_id]
+      response[:tag_scope] = material_index_tag_scope(filters, tag_graph)
+    end
+    if filters[:group_by] == 'parent_tag'
+      response[:groups] = material_index_groups(materials, tag_graph)
+    end
+
+    render json: response
   end
 
   def show
@@ -198,9 +211,18 @@ class MaterialsController < ApplicationController
     direction = params[:direction].to_s.downcase
     direction = 'desc' unless ['asc', 'desc'].include?(direction)
 
+    group_by = params[:group_by].to_s.presence
+    group_by = 'none' unless ['none', 'parent_tag'].include?(group_by)
+
+    tag_id = params[:tag_id].to_i
+    tag_id = nil if tag_id <= 0
+
     { q: params[:q].to_s.strip.presence,
       tag_state:,
       media_kind:,
+      tag_id:,
+      include_descendants: bool?(:include_descendants),
+      group_by:,
       created_from: parse_time_param(:created_from),
       created_to: parse_time_param(:created_to),
       updated_from: parse_time_param(:updated_from),
@@ -270,6 +292,147 @@ class MaterialsController < ApplicationController
     end
   end
 
+  def apply_material_tag_filter q, filters, tag_graph
+    return q unless filters[:tag_id]
+
+    tag_ids =
+        if tag_graph
+          tag_graph[:scope_tag_ids]
+        else
+          [filters[:tag_id]]
+        end
+
+    q.where(tag_id: tag_ids)
+  end
+
+  def material_index_tag_graph filters
+    return nil unless filters[:tag_id]
+
+    children_by_parent_id = Hash.new { |h, k| h[k] = [] }
+    TagImplication.pluck(:parent_tag_id, :tag_id).each do |parent_id, child_id|
+      children_by_parent_id[parent_id] << child_id
+    end
+
+    scope_tag_ids =
+        if filters[:include_descendants]
+          collect_material_descendant_ids(filters[:tag_id], children_by_parent_id)
+        else
+          Set.new([filters[:tag_id]])
+        end
+    tags_by_id =
+        Tag
+        .joins(:tag_name)
+        .where(id: scope_tag_ids)
+        .pluck('tags.id', 'tag_names.name', 'tags.category', 'tags.deprecated_at')
+        .each_with_object({ }) do |(id, name, category, deprecated_at), hash|
+          hash[id] = { id:, name:, category:, deprecated: deprecated_at.present? }
+        end
+
+    selected_tag = tags_by_id[filters[:tag_id]]
+    return nil unless selected_tag
+
+    group_tag_id_by_tag_id = { }
+    children_by_parent_id[filters[:tag_id]].each do |child_tag_id|
+      assign_material_group_branch(child_tag_id,
+                                   children_by_parent_id:,
+                                   tags_by_id:,
+                                   group_tag_id_by_tag_id:,
+                                   current_group_tag_id: nil,
+                                   seen: Set.new([filters[:tag_id]]))
+    end
+
+    { selected_tag_id: filters[:tag_id],
+      selected_tag:,
+      scope_tag_ids: scope_tag_ids.to_a,
+      tags_by_id:,
+      group_tag_id_by_tag_id: }
+  end
+
+  def collect_material_descendant_ids selected_tag_id, children_by_parent_id
+    ids = Set.new([selected_tag_id])
+    stack = [selected_tag_id]
+
+    until stack.empty?
+      tag_id = stack.pop
+      children_by_parent_id[tag_id].each do |child_tag_id|
+        next if ids.include?(child_tag_id)
+
+        ids << child_tag_id
+        stack << child_tag_id
+      end
+    end
+
+    ids
+  end
+
+  def assign_material_group_branch tag_id, children_by_parent_id:, tags_by_id:,
+                                   group_tag_id_by_tag_id:, current_group_tag_id:, seen:
+    return if seen.include?(tag_id)
+
+    tag = tags_by_id[tag_id]
+    return unless tag
+
+    seen = seen.dup << tag_id
+    next_group_tag_id = current_group_tag_id
+    next_group_tag_id = tag_id if next_group_tag_id.nil? && !tag[:deprecated]
+    group_tag_id_by_tag_id[tag_id] = next_group_tag_id if next_group_tag_id
+
+    children_by_parent_id[tag_id].each do |child_tag_id|
+      assign_material_group_branch(child_tag_id,
+                                   children_by_parent_id:,
+                                   tags_by_id:,
+                                   group_tag_id_by_tag_id:,
+                                   current_group_tag_id: next_group_tag_id,
+                                   seen:)
+    end
+  end
+
+  def material_index_groups materials, tag_graph
+    return [] unless tag_graph
+
+    groups_by_key = { }
+
+    materials.each do |material|
+      next unless material.tag_id
+
+      group_tag_id =
+          if material.tag_id == tag_graph[:selected_tag_id]
+            tag_graph[:selected_tag_id]
+          else
+            tag_graph[:group_tag_id_by_tag_id][material.tag_id] || tag_graph[:selected_tag_id]
+          end
+
+      group_tag = tag_graph[:tags_by_id][group_tag_id]
+      next unless group_tag
+
+      key = "tag:#{ group_tag_id }"
+      group =
+          groups_by_key[key] ||= { key:,
+                                   tag: group_tag_repr(group_tag),
+                                   material_ids: [],
+                                   count: 0 }
+      group[:material_ids] << material.id
+      group[:count] += 1
+    end
+
+    groups_by_key.values.sort_by { |group| group[:tag][:name] }
+  end
+
+  def material_index_tag_scope filters, tag_graph
+    return nil unless tag_graph
+
+    {
+      tag: group_tag_repr(tag_graph[:selected_tag]),
+      include_descendants: filters[:include_descendants]
+    }
+  end
+
+  def group_tag_repr group_tag
+    { id: group_tag[:id],
+      name: group_tag[:name],
+      category: group_tag[:category] }
+  end
+
   def material_index_order_sql filters
     direction = filters[:direction] == 'asc' ? 'ASC' : 'DESC'
     sort_sql =
@@ -360,10 +523,7 @@ class MaterialsController < ApplicationController
         content_type: file.content_type,
     )
 
-    if file_sha256.present?
+    MaterialFileSha256.assign_metadata_sha256!(blob, file_sha256)
-      blob.metadata['sha256'] = file_sha256
-      blob.save! if blob.changed?
-    end
 
     blob
   ensure

backend/app/controllers/tags_controller.rb

@@ -245,10 +245,7 @@ class TagsController < ApplicationController
     return render_unprocessable_entity('カテゴリは必須です．', field: :category) if category.blank?
     return render_unprocessable_entity '廃止状態は必須です．', field: :deprecated unless params.key?(:deprecated)
 
-    if (name != tag.name &&
+    return unless validate_tag_rename(tag, name)
-        tag.in?([Tag.tagme, Tag.bot, Tag.no_deerjikist, Tag.video, Tag.niconico]))
-      return render_unprocessable_entity 'システム・タグの名称は変更できません．', field: :name
-    end
 
     alias_names = params[:aliases].to_s.split.uniq
     parent_names = params[:parent_tags].to_s.split.uniq
@@ -274,7 +271,7 @@ class TagsController < ApplicationController
       else
         tag.update!(category:, deprecated_at: deprecated ? Time.current : nil)
       end
-      tag.tag_name.update!(name:)
+      rename_tag_name!(tag, name) if name_changed
 
       alias_names << old_name if name_changed
       alias_names.delete(name)
@@ -310,6 +307,8 @@ class TagsController < ApplicationController
       return render_unprocessable_entity 'ニコタグは廃止できません．', field: :deprecated
     end
 
+    return unless validate_tag_rename(tag, name)
+
     if tag.nico? || (category.present? && category == 'nico')
       return render_unprocessable_entity 'ニコタグは変更できません．', field: :category
     end
@@ -321,7 +320,7 @@ class TagsController < ApplicationController
       name_changed = name.present? && name != old_name
       wiki_page = tag.tag_name.wiki_page if name_changed
 
-      tag.tag_name.update!(name:) if name.present?
+      rename_tag_name!(tag, name) if name_changed
       tag.update!(category:) if category.present?
       if deprecated_given && tag.deprecated? != deprecated
         tag.update!(deprecated_at: deprecated ? Time.current : nil)
@@ -379,12 +378,20 @@ class TagsController < ApplicationController
   end
 
   def visible_root_tag_ids graph
-    graph[:tags_by_id].filter_map do |tag_id, _attrs|
+    root_ids = Set.new
+
+    graph[:tags_by_id].each do |tag_id, attrs|
       next unless visible_root_tag?(tag_id, graph)
       next unless visible_subtree?(tag_id, graph)
 
-      tag_id
+      if attrs[:deprecated]
+        collect_visible_child_tag_ids(tag_id, graph, root_ids, Set.new)
+      else
+        root_ids << tag_id
+      end
     end
+
+    root_ids.to_a
   end
 
   def visible_root_tag? tag_id, graph
@@ -527,6 +534,67 @@ class TagsController < ApplicationController
         created_by_user:)
   end
 
+  def validate_tag_rename tag, name
+    return true if name.blank? || name == tag.name
+
+    if tag.in?([Tag.tagme, Tag.bot, Tag.no_deerjikist, Tag.video, Tag.niconico])
+      render_unprocessable_entity 'システム・タグの名称は変更できません．', field: :name
+      return false
+    end
+
+    target_tag_name = TagName.with_discarded.find_by(name:)
+    return true if target_tag_name.nil?
+    return true if target_tag_name.canonical_id?
+
+    render_unprocessable_entity 'その名前は既に使はれてゐます．', field: :name
+    false
+  end
+
+  def rename_tag_name! tag, name
+    return if name == tag.name
+
+    current_tag_name = tag.tag_name
+    target_tag_name = TagName.with_discarded.find_by(name:)
+
+    if target_tag_name.nil?
+      current_tag_name.update!(name:)
+      return
+    end
+
+    promote_tag_alias!(
+        tag,
+        current_tag_name:,
+        promoted_tag_name: target_tag_name)
+  end
+
+  def promote_tag_alias! tag, current_tag_name:, promoted_tag_name:
+    old_owner_tag = promoted_tag_name.canonical&.tag
+
+    if old_owner_tag && old_owner_tag != tag
+      TagVersioning.ensure_snapshot!(old_owner_tag, created_by_user: current_user)
+    end
+
+    promoted_tag_name.undiscard! if promoted_tag_name.discarded?
+    promoted_tag_name.update!(canonical: nil)
+
+    TagName.with_discarded
+           .where(canonical_id: current_tag_name.id)
+           .where.not(id: promoted_tag_name.id)
+           .find_each do |alias_tag_name|
+      alias_tag_name.update!(canonical: promoted_tag_name)
+    end
+
+    current_tag_name.wiki_page&.update!(tag_name: promoted_tag_name)
+    tag.update!(tag_name: promoted_tag_name)
+    current_tag_name.association(:wiki_page).reset
+    current_tag_name.association(:tag).reset
+    current_tag_name.reload.update!(canonical: promoted_tag_name)
+
+    return unless old_owner_tag && old_owner_tag != tag
+
+    record_tag_version!(old_owner_tag.reload, event_type: :update, created_by_user: current_user)
+  end
+
   def update_aliases! tag, alias_names
     alias_names = alias_names.uniq
 

backend/app/models/material.rb

@@ -1,6 +1,9 @@
 class Material < ApplicationRecord
   include MyDiscard
 
+  SOURCE_KINDS = ['uri', 'google_drive_path', 'google_drive_file',
+                  'legacy_drive_path'].freeze
+
   default_scope -> { kept }
 
   belongs_to :parent, class_name: 'Material', optional: true
@@ -20,7 +23,7 @@ class Material < ApplicationRecord
 
   validates :tag_id, uniqueness: true, allow_nil: true
   validates :source_kind,
-            inclusion: { in: MaterialSyncSuppression::SOURCE_KINDS },
+            inclusion: { in: SOURCE_KINDS },
             allow_blank: true
 
   validate :file_must_be_attached

backend/app/models/material_sync_source.rb

@@ -1,11 +1,13 @@
 class MaterialSyncSource < ApplicationRecord
+  SOURCE_KINDS = ['uri', 'google_drive_path', 'google_drive_file', 'legacy_drive_path'].freeze
+
   belongs_to :created_by_user, class_name: 'User', optional: true
   belongs_to :updated_by_user, class_name: 'User', optional: true
 
   validates :name, presence: true
   validates :source_kind,
             presence: true,
-            inclusion: { in: MaterialSyncSuppression::SOURCE_KINDS }
+            inclusion: { in: SOURCE_KINDS }
   validates :profile, presence: true, inclusion: { in: MaterialExportItem::VALID_PROFILES }
   validate :source_value_must_be_present
 
@@ -33,7 +35,7 @@ class MaterialSyncSource < ApplicationRecord
     when 'google_drive_file'
       source_file_id.present? || source_uri.present?
     when 'google_drive_path'
-      source_file_id.present? || source_uri.present? || source_path.present?
+      source_file_id.present? || source_uri.present?
     when 'legacy_drive_path'
       source_path.present?
     else

backend/app/services/google_drive/api_client.rb

@@ -11,6 +11,7 @@ module GoogleDrive
     DRIVE_ENDPOINT = 'https://www.googleapis.com/drive/v3'
     TOKEN_ENDPOINT = 'https://oauth2.googleapis.com/token'
     FOLDER_MIME_TYPE = 'application/vnd.google-apps.folder'
+    NATIVE_FILE_MIME_TYPE_PREFIX = 'application/vnd.google-apps.'
     DRIVE_SCOPE = 'https://www.googleapis.com/auth/drive.readonly'
 
     def initialize service_account_email: ENV['GOOGLE_DRIVE_SERVICE_ACCOUNT_EMAIL'],
@@ -25,24 +26,34 @@ module GoogleDrive
 
     def list_material_files_under_folder folder_id
       files = []
+      each_material_file_under_folder(folder_id) { |entry| files << entry }
+      files
+    end
+
+    def each_material_file_under_folder folder_id
+      return enum_for(__method__, folder_id) unless block_given?
+
       walk_folder(folder_id, nil) do |entry, relative_path|
         next if entry['mimeType'] == FOLDER_MIME_TYPE
+        next if native_file?(entry['mimeType'])
 
-        files << build_file_entry(entry, relative_path)
+        yield build_file_entry(entry, relative_path)
       end
-      files
     end
 
     def fetch_material_file file_id
       metadata = get_file(file_id)
+      return nil if native_file?(metadata['mimeType'])
+
       build_file_entry(metadata, metadata['name'])
     end
 
     def download_to_tempfile file_id, filename:
       tempfile = Tempfile.new(['material-sync', File.extname(filename.to_s)])
+      tempfile.binmode
       request_binary("/files/#{ file_id }",
                      { alt: 'media', supportsAllDrives: true }) do |chunk|
-        tempfile.write(chunk)
+        tempfile.write(chunk.b)
       end
       tempfile.rewind
       tempfile
@@ -85,6 +96,7 @@ module GoogleDrive
         name: entry['name'],
         mime_type: entry['mimeType'],
         relative_path: MaterialSyncExportPath.normalize_path(relative_path),
+        sha256_checksum: entry['sha256Checksum'],
         web_view_link: entry['webViewLink'],
         web_content_link: entry['webContentLink'] }
     end
@@ -97,7 +109,8 @@ module GoogleDrive
         response =
             request_json('/files', {
                 q: "'#{ folder_id }' in parents and trashed = false",
-                fields: 'nextPageToken,files(id,name,mimeType,webViewLink,webContentLink)',
+                fields: 'nextPageToken,files(id,name,mimeType,sha256Checksum,' \
+                        'webViewLink,webContentLink)',
                 orderBy: 'folder,name',
                 pageSize: 1000,
                 supportsAllDrives: true,
@@ -113,7 +126,7 @@ module GoogleDrive
 
     def get_file file_id
       request_json("/files/#{ file_id }",
-                   fields: 'id,name,mimeType,webViewLink,webContentLink',
+                   fields: 'id,name,mimeType,sha256Checksum,webViewLink,webContentLink',
                    supportsAllDrives: true)
     end
 
@@ -127,13 +140,14 @@ module GoogleDrive
     end
 
     def request_binary path, params = {}
-      response = request(:get, path, params:)
+      request(:get, path, params:) do |response|
-      unless response.is_a?(Net::HTTPSuccess)
+        unless response.is_a?(Net::HTTPSuccess)
-        raise "Google Drive download error: #{ response.code } #{ response.body }"
+          raise "Google Drive download error: #{ response.code } #{ response.body }"
-      end
+        end
 
-      response.read_body do |chunk|
+        response.read_body do |chunk|
-        yield chunk
+          yield chunk.b
+        end
       end
     end
 
@@ -156,7 +170,13 @@ module GoogleDrive
                       use_ssl: true,
                       open_timeout: 10,
                       read_timeout: 60) do |http|
-        http.request(request)
+        if block_given?
+          http.request(request) do |response|
+            return yield response
+          end
+        else
+          http.request(request)
+        end
       end
     end
 
@@ -205,5 +225,9 @@ module GoogleDrive
 
       OpenSSL::PKey::RSA.new(raw)
     end
+
+    def native_file? mime_type
+      mime_type.to_s.start_with?(NATIVE_FILE_MIME_TYPE_PREFIX)
+    end
   end
 end

backend/app/services/material_file_sha256.rb

@@ -1,16 +1,39 @@
 require 'digest'
+require 'json'
 
 class MaterialFileSha256
+  def self.blob_metadata blob
+    metadata = blob.metadata
+    return metadata if metadata.is_a?(Hash)
+    return { } if metadata.blank?
+
+    JSON.parse(metadata)
+  rescue JSON::ParserError
+    { }
+  end
+
+  def self.metadata_sha256 blob
+    blob_metadata(blob)['sha256'].presence
+  end
+
+  def self.assign_metadata_sha256! blob, sha256
+    return if sha256.blank?
+
+    metadata = blob_metadata(blob)
+    metadata['sha256'] = sha256
+    blob.metadata = metadata
+    blob.save! if blob.changed?
+  end
+
   def self.from_blob blob, allow_download: false
-    sha256 = blob.metadata['sha256']
+    sha256 = metadata_sha256(blob)
     return sha256 if sha256.present?
     return nil unless allow_download
 
     begin
       blob.open do |file|
         sha256 = Digest::SHA256.file(file.path).hexdigest
-        blob.metadata['sha256'] = sha256
+        assign_metadata_sha256!(blob, sha256)
-        blob.save! if blob.changed?
         sha256
       end
     rescue ActiveStorage::FileNotFoundError, ArgumentError => error

backend/app/services/material_sync_importer.rb

@@ -28,6 +28,13 @@ class MaterialSyncImporter
         Material
         .unscoped
         .find_or_initialize_by(normalized_source_key: key)
+    if unchanged?(material, source)
+      return Result.new(material:,
+                        action: :unchanged,
+                        suppressed: false,
+                        suppression: nil)
+    end
+
     event_type =
         if material.new_record?
           :create
@@ -37,13 +44,19 @@ class MaterialSyncImporter
           :update
         end
     uploaded_blob = uploaded_blob!
+    if @import_block
+      return Result.new(material: nil,
+                        action: :suppressed,
+                        suppressed: true,
+                        suppression: @import_block)
+    end
 
     Material.transaction do
       if material.persisted?
         MaterialVersionRecorder.ensure_snapshot!(material,
                                                  created_by_user: @attributes[:updated_by_user])
       end
-      material.assign_attributes(material_attributes.merge(source))
+      material.assign_attributes(material_attributes_for(material).merge(source))
       material.discarded_at = nil if material.respond_to?(:discarded_at=)
       material.file.attach(uploaded_blob) if uploaded_blob
       material.save!
@@ -81,10 +94,28 @@ class MaterialSyncImporter
                                                  source_file_id: source[:source_file_id])
   end
 
-  def material_attributes
+  def material_attributes_for material
-    @attributes.except(:source_kind, :source_uri, :source_path, :source_file_id,
+    attrs =
-                       :file_blob, :file_tempfile, :filename, :content_type,
+        @attributes
-                       :file_sha256, :export_path, :profile)
+        .except(:source_kind, :source_uri, :source_path, :source_file_id,
+                :file_blob, :file_tempfile, :file_downloader,
+                :filename, :content_type,
+                :file_sha256, :export_path, :profile, :tag, :url)
+
+    if material.new_record?
+      attrs[:tag] = @attributes[:tag] if @attributes.key?(:tag)
+      attrs[:url] = @attributes[:url] if @attributes.key?(:url)
+      return attrs
+    end
+
+    if @attributes.key?(:tag) && @attributes[:tag].present?
+      attrs[:tag] = @attributes[:tag]
+    end
+    if @attributes.key?(:url) && @attributes[:url].present?
+      attrs[:url] = @attributes[:url]
+    end
+
+    attrs
   end
 
   def suppression_for source
@@ -100,33 +131,44 @@ class MaterialSyncImporter
   def uploaded_blob!
     return @attributes[:file_blob] if @attributes[:file_blob]
 
-    tempfile = @attributes[:file_tempfile]
+    tempfile = upload_tempfile
     return nil unless tempfile
 
     tempfile.rewind
+    file_sha256 = @attributes[:file_sha256] || Digest::SHA256.file(tempfile.path).hexdigest
+    @attributes[:file_sha256] = file_sha256
+
+    @import_block = MaterialImportBlockMatcher.match_for_sha256(file_sha256)
+    if @import_block
+      tempfile.rewind
+      return nil
+    end
+
     blob = ActiveStorage::Blob.create_and_upload!(
         io: tempfile,
         filename: @attributes[:filename],
         content_type: @attributes[:content_type])
-    file_sha256 = @attributes[:file_sha256] || Digest::SHA256.file(tempfile.path).hexdigest
+    MaterialFileSha256.assign_metadata_sha256!(blob, file_sha256)
-    blob.metadata['sha256'] = file_sha256 if file_sha256.present?
-    blob.save! if blob.changed?
     tempfile.rewind
     blob
   end
 
+  def upload_tempfile
+    return @upload_tempfile if defined?(@upload_tempfile)
+
+    @upload_tempfile = @attributes[:file_tempfile]
+    if @upload_tempfile.blank? && @attributes[:file_downloader]
+      @upload_tempfile = @attributes[:file_downloader].call
+    end
+    @upload_tempfile
+  end
+
   def upsert_export_item! material
-    export_path = @attributes[:export_path].to_s.strip
+    export_path = resolved_export_path(material)
     return if export_path.blank?
 
-    profile = @attributes[:profile].presence || 'legacy_drive'
+    item = material.material_export_items.find_or_initialize_by(profile: effective_profile)
-    path = export_path
+    item.export_path = export_path
-    if export_path_taken_by_other?(material, profile, path)
-      path = MaterialSyncExportPath.uniquify(path, @attributes[:source_file_id])
-    end
-
-    item = material.material_export_items.find_or_initialize_by(profile:)
-    item.export_path = path
     item.enabled = true
     item.created_by_user ||= @attributes[:created_by_user]
     item.save!
@@ -140,11 +182,78 @@ class MaterialSyncImporter
   end
 
   def close_tempfile!
-    tempfile = @attributes[:file_tempfile]
+    tempfile = upload_tempfile
     return unless tempfile
 
     tempfile.close! unless tempfile.closed?
   rescue StandardError
     nil
   end
+
+  def unchanged? material, source
+    return false if material.new_record? || material.discarded?
+    return false unless same_source_attributes?(material, source)
+    return false unless same_export_path?(material)
+    return false unless same_material_attributes?(material)
+
+    same_file_snapshot?(material)
+  end
+
+  def same_source_attributes? material, source
+    material.source_kind == source[:source_kind] \
+      && material.source_uri == source[:source_uri] \
+      && material.source_path == source[:source_path] \
+      && material.source_file_id == source[:source_file_id]
+  end
+
+  def same_export_path? material
+    expected = resolved_export_path(material)
+    current = material.material_export_items.find { |item| item.profile == effective_profile }
+
+    return current.blank? if expected.blank?
+
+    current&.enabled && current.export_path == expected
+  end
+
+  def same_material_attributes? material
+    same_tag_attribute?(material) && same_url_attribute?(material)
+  end
+
+  def same_file_snapshot? material
+    expected_sha256 = @attributes[:file_sha256].to_s.presence
+
+    if expected_sha256.present?
+      return false unless material.file.attached?
+
+      return MaterialFileSha256.metadata_sha256(material.file.blob) == expected_sha256
+    end
+
+    !material.file.attached?
+  end
+
+  def effective_profile
+    @attributes[:profile].presence || 'legacy_drive'
+  end
+
+  def resolved_export_path material
+    export_path = @attributes[:export_path].to_s.strip
+    return export_path if export_path.blank?
+    return export_path unless export_path_taken_by_other?(material, effective_profile, export_path)
+
+    MaterialSyncExportPath.uniquify(export_path, @attributes[:source_file_id])
+  end
+
+  def same_tag_attribute? material
+    return true unless @attributes.key?(:tag)
+    return true if @attributes[:tag].blank?
+
+    material.tag_id == @attributes[:tag].id
+  end
+
+  def same_url_attribute? material
+    return true unless @attributes.key?(:url)
+    return true if @attributes[:url].blank?
+
+    material.url == @attributes[:url]
+  end
 end

backend/app/services/material_sync_runner.rb

@@ -1,13 +1,13 @@
-require 'digest'
-
 class MaterialSyncRunner
-  Result = Struct.new(:imported, :updated, :suppressed, :failed, :errors, keyword_init: true)
+  Result = Struct.new(:imported, :updated, :unchanged, :suppressed, :failed,
+                      :errors, keyword_init: true)
 
   def self.sync_enabled!
     results = MaterialSyncSource.enabled.order(:id).map { |source| new(source).sync! }
 
     Result.new(imported: results.sum(&:imported),
                updated: results.sum(&:updated),
+               unchanged: results.sum(&:unchanged),
                suppressed: results.sum(&:suppressed),
                failed: results.sum(&:failed),
                errors: results.flat_map(&:errors))
@@ -18,10 +18,17 @@ class MaterialSyncRunner
   end
 
   def sync!
-    result = Result.new(imported: 0, updated: 0, suppressed: 0, failed: 0, errors: [])
+    result = Result.new(imported: 0, updated: 0, unchanged: 0,
+                        suppressed: 0, failed: 0, errors: [])
 
-    candidates.each do |candidate|
+    if @source.source_kind == 'google_drive_path'
-      sync_candidate!(candidate, result)
+      sync_google_drive_path!(result)
+    else
+      candidates.each do |candidate|
+        next if candidate.blank?
+
+        sync_candidate!(candidate, result)
+      end
     end
 
     @source.update!(last_synced_at: Time.current)
@@ -40,8 +47,6 @@ class MaterialSyncRunner
     case @source.source_kind
     when 'uri'
       [uri_candidate]
-    when 'google_drive_path'
-      google_drive_path_candidates
     when 'google_drive_file'
       [google_drive_file_candidate]
     when 'legacy_drive_path'
@@ -101,15 +106,30 @@ class MaterialSyncRunner
   def google_drive_path_candidates
     folder_id = google_drive_folder_id
     Enumerator.new do |entries|
-      drive_client.list_material_files_under_folder(folder_id).each do |entry|
+      drive_client.each_material_file_under_folder(folder_id).each do |entry|
         entries << build_google_drive_candidate(entry)
       end
     end
   end
 
+  def sync_google_drive_path! result
+    folder_id = google_drive_folder_id
+    scanned_count = 0
+
+    drive_client.each_material_file_under_folder(folder_id) do |entry|
+      scanned_count += 1
+      sync_candidate!(build_google_drive_candidate(entry), result)
+      log_google_drive_progress(folder_id, scanned_count, result) if progress_log_scan_count?(scanned_count)
+    end
+
+    log_google_drive_progress(folder_id, scanned_count, result, summary: true)
+  end
+
   def google_drive_file_candidate
-    build_google_drive_candidate(drive_client.fetch_material_file(google_drive_file_id),
+    entry = drive_client.fetch_material_file(google_drive_file_id)
-                                 single_file: true)
+    return nil unless entry
+
+    build_google_drive_candidate(entry, single_file: true)
   end
 
   def build_google_drive_candidate entry, single_file: false
@@ -124,10 +144,6 @@ class MaterialSyncRunner
                                      relative_path:,
                                      filename: entry[:name],
                                      source_file_id: entry[:id])
-    tempfile =
-        drive_client.download_to_tempfile(entry[:id], filename: entry[:name])
-    file_sha256 = Digest::SHA256.file(tempfile.path).hexdigest
-    tempfile.rewind
 
     { source_kind: 'google_drive_file',
       source_uri: entry[:web_view_link] || google_drive_file_url(entry[:id]),
@@ -135,8 +151,10 @@ class MaterialSyncRunner
       source_file_id: entry[:id],
       filename: entry[:name],
       content_type: entry[:mime_type],
-      file_tempfile: tempfile,
+      file_downloader: lambda {
-      file_sha256:,
+        drive_client.download_to_tempfile(entry[:id], filename: entry[:name])
+      },
+      file_sha256: entry[:sha256_checksum],
       export_path:,
       profile: @source.profile,
       tag: nil,
@@ -171,13 +189,17 @@ class MaterialSyncRunner
 
   def google_drive_folder_id
     google_drive_target_id.tap do |id|
-      raise ArgumentError, 'google_drive_path source_file_id or source_uri is required' if id.blank?
+      if id.blank?
+        raise ArgumentError, 'google_drive_path source_file_id or source_uri is required'
+      end
     end
   end
 
   def google_drive_file_id
     google_drive_target_id.tap do |id|
-      raise ArgumentError, 'google_drive_file source_file_id or source_uri is required' if id.blank?
+      if id.blank?
+        raise ArgumentError, 'google_drive_file source_file_id or source_uri is required'
+      end
     end
   end
 
@@ -201,10 +223,27 @@ class MaterialSyncRunner
   def log_result result
     Rails.logger.info(material_sync_log(imported: result.imported,
                                         updated: result.updated,
+                                        unchanged: result.unchanged,
                                         suppressed: result.suppressed,
                                         failed: result.failed))
   end
 
+  def progress_log_scan_count? scanned_count
+    scanned_count == 1 || (scanned_count % 50).zero?
+  end
+
+  def log_google_drive_progress folder_id, scanned_count, result, summary: false
+    Rails.logger.info(
+        material_sync_log(folder_id:,
+                          scanned_count:,
+                          imported: result.imported,
+                          updated: result.updated,
+                          unchanged: result.unchanged,
+                          suppressed: result.suppressed,
+                          failed: result.failed,
+                          progress: summary ? 'summary' : 'scan'))
+  end
+
   def material_sync_log fields
     { material_sync_source_id: @source.id,
       material_sync_source_name: @source.name }.merge(fields).to_json

backend/app/services/material_version_recorder.rb

@@ -33,6 +33,11 @@ class MaterialVersionRecorder < VersionRecorder
       tag: @record.tag,
       tag_name: @record.tag&.name,
       tag_category: @record.tag&.category,
+      source_kind: @record.source_kind,
+      source_uri: @record.source_uri,
+      source_path: @record.source_path,
+      source_file_id: @record.source_file_id,
+      normalized_source_key: @record.normalized_source_key,
       export_paths_json: @record.snapshot_export_paths,
       discarded_at: @record.discarded_at,
       file_blob_id: file_snapshot[:file_blob_id],
@@ -52,7 +57,7 @@ class MaterialVersionRecorder < VersionRecorder
       file_content_type: blob.content_type,
       file_byte_size: blob.byte_size,
       file_checksum: blob.checksum,
-      file_sha256: blob.metadata['sha256'] }
+      file_sha256: MaterialFileSha256.metadata_sha256(blob) }
   end
 
   def empty_file_snapshot

backend/db/migrate/20260623000000_enhance_material_management.rb

@@ -2,9 +2,6 @@ class EnhanceMaterialManagement < ActiveRecord::Migration[8.0]
   def up
     change_table :materials, bulk: true do |t|
       t.integer :version_no, null: false, default: 1
-      t.datetime :file_suppressed_at
-      t.references :file_suppressed_by_user, foreign_key: { to_table: :users }
-      t.string :file_suppression_reason
     end
 
     change_table :material_versions, bulk: true do |t|
@@ -18,8 +15,6 @@ class EnhanceMaterialManagement < ActiveRecord::Migration[8.0]
       t.bigint :file_byte_size
       t.string :file_checksum
       t.string :file_sha256
-      t.datetime :file_suppressed_at
-      t.string :file_suppression_reason
     end
 
     execute <<~SQL.squish
@@ -35,7 +30,7 @@ class EnhanceMaterialManagement < ActiveRecord::Migration[8.0]
     add_index :material_versions, :file_blob_id
 
     add_check_constraint :material_versions,
-                         "event_type IN ('create', 'update', 'discard', 'restore', 'suppress')",
+                         "event_type IN ('create', 'update', 'discard', 'restore')",
                          name: 'material_versions_event_type_valid'
 
     create_table :material_export_items do |t|
@@ -87,12 +82,7 @@ class EnhanceMaterialManagement < ActiveRecord::Migration[8.0]
     remove_column :material_versions, :file_byte_size
     remove_column :material_versions, :file_checksum
     remove_column :material_versions, :file_sha256
-    remove_column :material_versions, :file_suppressed_at
-    remove_column :material_versions, :file_suppression_reason
 
-    remove_reference :materials, :file_suppressed_by_user, foreign_key: { to_table: :users }
     remove_column :materials, :version_no
-    remove_column :materials, :file_suppressed_at
-    remove_column :materials, :file_suppression_reason
   end
 end

backend/db/migrate/20260626000000_add_source_snapshot_to_material_versions.rb

@@ -0,0 +1,19 @@
+class AddSourceSnapshotToMaterialVersions < ActiveRecord::Migration[8.0]
+  def change
+    unless column_exists?(:material_versions, :source_kind)
+      add_column :material_versions, :source_kind, :string
+    end
+    unless column_exists?(:material_versions, :source_uri)
+      add_column :material_versions, :source_uri, :string
+    end
+    unless column_exists?(:material_versions, :source_path)
+      add_column :material_versions, :source_path, :string
+    end
+    unless column_exists?(:material_versions, :source_file_id)
+      add_column :material_versions, :source_file_id, :string
+    end
+    unless column_exists?(:material_versions, :normalized_source_key)
+      add_column :material_versions, :normalized_source_key, :string
+    end
+  end
+end

backend/db/migrate/20260626010000_backfill_initial_material_versions.rb

@@ -0,0 +1,171 @@
+require 'json'
+
+class BackfillInitialMaterialVersions < ActiveRecord::Migration[8.0]
+  class MigrationMaterial < ActiveRecord::Base
+    self.table_name = 'materials'
+  end
+
+  class MigrationMaterialExportItem < ActiveRecord::Base
+    self.table_name = 'material_export_items'
+  end
+
+  class MigrationMaterialVersion < ActiveRecord::Base
+    self.table_name = 'material_versions'
+  end
+
+  class MigrationStorageAttachment < ActiveRecord::Base
+    self.table_name = 'active_storage_attachments'
+  end
+
+  class MigrationStorageBlob < ActiveRecord::Base
+    self.table_name = 'active_storage_blobs'
+  end
+
+  class MigrationTag < ActiveRecord::Base
+    self.table_name = 'tags'
+  end
+
+  class MigrationTagName < ActiveRecord::Base
+    self.table_name = 'tag_names'
+  end
+
+  def up
+    say_with_time 'Backfilling initial material versions' do
+      materials_without_versions.find_in_batches(batch_size: 500) do |materials|
+        material_ids = materials.map(&:id)
+        tags_by_id = load_tags(materials.map(&:tag_id).compact.uniq)
+        export_paths_by_material_id = load_export_paths(material_ids)
+        file_snapshots_by_material_id = load_file_snapshots(material_ids)
+
+        rows = materials.map do |material|
+          tag = tags_by_id[material.tag_id]
+          file_snapshot = file_snapshots_by_material_id[material.id] || empty_file_snapshot
+
+          { material_id: material.id,
+            version_no: 1,
+            event_type: 'create',
+            url: material.url,
+            parent_id: material.parent_id,
+            tag_id: material.tag_id,
+            tag_name: tag&.fetch(:name, nil),
+            tag_category: tag&.fetch(:category, nil),
+            source_kind: material.source_kind,
+            source_uri: material.source_uri,
+            source_path: material.source_path,
+            source_file_id: material.source_file_id,
+            normalized_source_key: material.normalized_source_key,
+            export_paths_json: export_paths_by_material_id[material.id] || { },
+            discarded_at: material.discarded_at,
+            file_blob_id: file_snapshot[:file_blob_id],
+            file_filename: file_snapshot[:file_filename],
+            file_content_type: file_snapshot[:file_content_type],
+            file_byte_size: file_snapshot[:file_byte_size],
+            file_checksum: file_snapshot[:file_checksum],
+            file_sha256: file_snapshot[:file_sha256],
+            created_by_user_id: material.created_by_user_id,
+            updated_by_user_id: material.updated_by_user_id,
+            created_at: material.created_at,
+            updated_at: material.created_at }
+        end
+
+        MigrationMaterialVersion.insert_all!(rows) if rows.present?
+      end
+    end
+
+    execute <<~SQL.squish
+      UPDATE materials
+      SET version_no = COALESCE(
+        (
+          SELECT MAX(material_versions.version_no)
+          FROM material_versions
+          WHERE material_versions.material_id = materials.id
+        ),
+        1
+      )
+    SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+
+  private
+
+  def materials_without_versions
+    MigrationMaterial.where.not(id: MigrationMaterialVersion.select(:material_id))
+  end
+
+  def load_tags tag_ids
+    return { } if tag_ids.empty?
+
+    tag_name_ids_by_tag_id = MigrationTag.where(id: tag_ids).pluck(:id, :tag_name_id).to_h
+    tag_names_by_id =
+        MigrationTagName
+        .where(id: tag_name_ids_by_tag_id.values.uniq)
+        .pluck(:id, :name)
+        .to_h
+    categories_by_tag_id = MigrationTag.where(id: tag_ids).pluck(:id, :category).to_h
+
+    tag_ids.each_with_object({ }) do |tag_id, hash|
+      hash[tag_id] = { name: tag_names_by_id[tag_name_ids_by_tag_id[tag_id]],
+                       category: categories_by_tag_id[tag_id] }
+    end
+  end
+
+  def load_export_paths material_ids
+    MigrationMaterialExportItem
+      .where(material_id: material_ids)
+      .order(:material_id, :profile)
+      .pluck(:material_id, :profile, :export_path)
+      .each_with_object({ }) do |(material_id, profile, export_path), hash|
+        hash[material_id] ||= { }
+        hash[material_id][profile] = export_path
+      end
+  end
+
+  def load_file_snapshots material_ids
+    attachments_by_material_id =
+        MigrationStorageAttachment
+        .where(record_type: 'Material', name: 'file', record_id: material_ids)
+        .pluck(:record_id, :blob_id)
+        .to_h
+
+    blobs_by_id =
+        MigrationStorageBlob
+        .where(id: attachments_by_material_id.values.uniq)
+        .index_by(&:id)
+
+    attachments_by_material_id.each_with_object({ }) do |(material_id, blob_id), hash|
+      blob = blobs_by_id[blob_id]
+      next unless blob
+
+      hash[material_id] = {
+        file_blob_id: blob.id,
+        file_filename: blob.filename.to_s,
+        file_content_type: blob.content_type,
+        file_byte_size: blob.byte_size,
+        file_checksum: blob.checksum,
+        file_sha256: blob_metadata(blob)['sha256']
+      }
+    end
+  end
+
+  def empty_file_snapshot
+    { file_blob_id: nil,
+      file_filename: nil,
+      file_content_type: nil,
+      file_byte_size: nil,
+      file_checksum: nil,
+      file_sha256: nil }
+  end
+
+  def blob_metadata blob
+    metadata = blob.metadata
+    return metadata if metadata.is_a?(Hash)
+    return { } if metadata.blank?
+
+    JSON.parse(metadata)
+  rescue JSON::ParserError
+    { }
+  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_06_25_010000) do
+ActiveRecord::Schema[8.0].define(version: 2026_06_26_010000) 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
@@ -72,6 +72,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.index ["correct_post_id"], name: "index_gekanator_games_on_correct_post_id"
     t.index ["guessed_post_id"], name: "index_gekanator_games_on_guessed_post_id"
     t.index ["user_id"], name: "index_gekanator_games_on_user_id"
+    t.check_constraint "`question_count` >= 0", name: "chk_gekanator_games_question_count_nonnegative"
   end
 
   create_table "gekanator_question_examples", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
@@ -213,6 +214,11 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.bigint "file_byte_size"
     t.string "file_checksum"
     t.string "file_sha256"
+    t.string "source_kind"
+    t.string "source_uri"
+    t.string "source_path"
+    t.string "source_file_id"
+    t.string "normalized_source_key"
     t.index ["created_by_user_id"], name: "index_material_versions_on_created_by_user_id"
     t.index ["discarded_at"], name: "index_material_versions_on_discarded_at"
     t.index ["file_blob_id"], name: "index_material_versions_on_file_blob_id"
@@ -269,9 +275,10 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.datetime "created_at", null: false
     t.bigint "created_by_user_id"
     t.index ["created_at"], name: "index_nico_tag_versions_on_created_at"
-    t.index ["created_by_user_id", "created_at"], name: "index_nico_tag_versions_on_created_by_user_id_and_created_at"
+    t.index ["created_by_user_id", "created_at"], name: "index_nico_tag_versions_on_created_by_user_id_and_created_at", order: { created_at: :desc }
-    t.index ["tag_id", "created_at"], name: "index_nico_tag_versions_on_tag_id_and_created_at"
+    t.index ["tag_id", "created_at"], name: "index_nico_tag_versions_on_tag_id_and_created_at", order: { created_at: :desc }
     t.index ["tag_id", "version_no"], name: "index_nico_tag_versions_on_tag_id_and_version_no", unique: true
+    t.check_constraint "`version_no` > 0", name: "nico_tag_versions_version_no_positive"
   end
 
   create_table "post_implications", primary_key: ["post_id", "parent_post_id"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
@@ -280,13 +287,14 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.index ["parent_post_id"], name: "index_post_implications_on_parent_post_id"
+    t.check_constraint "`post_id` <> `parent_post_id`", name: "chk_post_implications_no_self"
   end
 
   create_table "post_similarities", primary_key: ["post_id", "target_post_id"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "post_id", null: false
     t.bigint "target_post_id", null: false
     t.float "cos", null: false
-    t.index ["post_id", "cos"], name: "index_post_similarities_on_post_id_and_cos"
+    t.index ["post_id", "cos"], name: "index_post_similarities_on_post_id_and_cos", order: { cos: :desc }
     t.index ["target_post_id"], name: "index_post_similarities_on_target_post_id"
   end
 
@@ -326,6 +334,8 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.index ["created_by_user_id"], name: "index_post_versions_on_created_by_user_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|
@@ -340,6 +350,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.integer "version_no", null: false
     t.index ["uploaded_user_id"], name: "index_posts_on_uploaded_user_id"
     t.index ["url"], name: "index_posts_on_url", unique: true
+    t.check_constraint "`version_no` > 0", name: "chk_posts_version_no_positive"
   end
 
   create_table "settings", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
@@ -386,7 +397,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.bigint "tag_id", null: false
     t.bigint "target_tag_id", null: false
     t.float "cos", null: false
-    t.index ["tag_id", "cos"], name: "index_tag_similarities_on_tag_id_and_cos"
+    t.index ["tag_id", "cos"], name: "index_tag_similarities_on_tag_id_and_cos", order: { cos: :desc }
     t.index ["target_tag_id"], name: "index_tag_similarities_on_target_tag_id"
   end
 
@@ -396,30 +407,32 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.string "event_type", null: false
     t.string "name", null: false
     t.string "category", null: false
+    t.datetime "deprecated_at"
     t.text "aliases", null: false
     t.text "parent_tag_ids", null: false
-    t.datetime "deprecated_at"
     t.datetime "created_at", null: false
     t.bigint "created_by_user_id"
     t.index ["created_at"], name: "index_tag_versions_on_created_at"
-    t.index ["created_by_user_id", "created_at"], name: "index_tag_versions_on_created_by_user_id_and_created_at"
+    t.index ["created_by_user_id", "created_at"], name: "index_tag_versions_on_created_by_user_id_and_created_at", order: { created_at: :desc }
-    t.index ["tag_id", "created_at"], name: "index_tag_versions_on_tag_id_and_created_at"
+    t.index ["tag_id", "created_at"], name: "index_tag_versions_on_tag_id_and_created_at", order: { created_at: :desc }
     t.index ["tag_id", "version_no"], name: "index_tag_versions_on_tag_id_and_version_no", unique: true
+    t.check_constraint "`version_no` > 0", name: "tag_versions_version_no_positive"
   end
 
   create_table "tags", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "tag_name_id", null: false
     t.string "category", default: "general", null: false
-    t.datetime "deprecated_at"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.integer "post_count", default: 0, null: false
+    t.datetime "deprecated_at"
     t.datetime "discarded_at"
     t.integer "version_no", null: false
     t.index ["deprecated_at"], name: "index_tags_on_deprecated_at"
     t.index ["discarded_at"], name: "index_tags_on_discarded_at"
     t.index ["tag_name_id"], name: "index_tags_on_tag_name_id", unique: true
     t.check_constraint "(`deprecated_at` is null) or (`category` <> _utf8mb4'nico')", name: "chk_tags_deprecated_at_not_nico"
+    t.check_constraint "`version_no` > 0", name: "chk_tags_version_no_positive"
   end
 
   create_table "theatre_comments", primary_key: ["theatre_id", "no"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
@@ -544,6 +557,19 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.index ["banned_at"], name: "index_users_on_banned_at"
   end
 
+  create_table "wiki_assets", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "wiki_page_id", null: false
+    t.integer "no", null: false
+    t.string "alt_text"
+    t.binary "sha256", limit: 32, null: false
+    t.bigint "created_by_user_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["created_by_user_id"], name: "index_wiki_assets_on_created_by_user_id"
+    t.index ["wiki_page_id", "no"], name: "index_wiki_assets_on_wiki_page_id_and_no", unique: true
+    t.index ["wiki_page_id", "sha256"], name: "index_wiki_assets_on_wiki_page_id_and_sha256", unique: true
+  end
+
   create_table "wiki_lines", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "sha256", limit: 64, null: false
     t.text "body", null: false
@@ -560,11 +586,13 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.datetime "discarded_at"
+    t.integer "next_asset_no", default: 1, null: false
     t.integer "version_no", null: false
     t.index ["created_user_id"], name: "index_wiki_pages_on_created_user_id"
     t.index ["discarded_at"], name: "index_wiki_pages_on_discarded_at"
     t.index ["tag_name_id"], name: "index_wiki_pages_on_tag_name_id", unique: true
     t.index ["updated_user_id"], name: "index_wiki_pages_on_updated_user_id"
+    t.check_constraint "`version_no` > 0", name: "chk_wiki_pages_version_no_positive"
   end
 
   create_table "wiki_revision_lines", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
@@ -609,6 +637,8 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
     t.index ["created_by_user_id"], name: "index_wiki_versions_on_created_by_user_id"
     t.index ["wiki_page_id", "version_no"], name: "index_wiki_versions_on_wiki_page_id_and_version_no", unique: true
     t.index ["wiki_page_id"], name: "index_wiki_versions_on_wiki_page_id"
+    t.check_constraint "`event_type` in (_utf8mb4'create',_utf8mb4'update',_utf8mb4'discard',_utf8mb4'restore')", name: "wiki_versions_event_type_valid"
+    t.check_constraint "`version_no` > 0", name: "wiki_versions_version_no_positive"
   end
 
   add_foreign_key "active_storage_attachments", "active_storage_blobs", column: "blob_id"
@@ -687,6 +717,8 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_25_010000) do
   add_foreign_key "user_ips", "users"
   add_foreign_key "user_post_views", "posts"
   add_foreign_key "user_post_views", "users"
+  add_foreign_key "wiki_assets", "users", column: "created_by_user_id"
+  add_foreign_key "wiki_assets", "wiki_pages"
   add_foreign_key "wiki_pages", "tag_names"
   add_foreign_key "wiki_pages", "users", column: "created_user_id"
   add_foreign_key "wiki_pages", "users", column: "updated_user_id"

backend/db/seeds.rb

@@ -9,19 +9,19 @@
 #   end
 
 material_sync_source_uri = ENV['MATERIAL_SYNC_SOURCE_URI']
-material_sync_source_tag_name = ENV['MATERIAL_SYNC_SOURCE_TAG_NAME']
+material_sync_source_file_id = ENV['MATERIAL_SYNC_SOURCE_FILE_ID']
 
-if material_sync_source_uri.present? && material_sync_source_tag_name.present?
+if material_sync_source_uri.present? || material_sync_source_file_id.present?
   source = MaterialSyncSource.find_or_initialize_by(
       name: ENV.fetch('MATERIAL_SYNC_SOURCE_NAME', 'Legacy URI material sync'))
   source.assign_attributes(
       source_kind: ENV.fetch('MATERIAL_SYNC_SOURCE_KIND', 'uri'),
       source_uri: material_sync_source_uri,
       source_path: ENV['MATERIAL_SYNC_SOURCE_PATH'],
-      source_file_id: ENV['MATERIAL_SYNC_SOURCE_FILE_ID'],
+      source_file_id: material_sync_source_file_id,
       profile: ENV.fetch('MATERIAL_SYNC_SOURCE_PROFILE', 'legacy_drive'),
       enabled: ENV.fetch('MATERIAL_SYNC_SOURCE_ENABLED', 'true') != 'false',
-      default_tag_name: material_sync_source_tag_name,
+      default_tag_name: ENV['MATERIAL_SYNC_SOURCE_TAG_NAME'],
       export_path_prefix: ENV['MATERIAL_SYNC_EXPORT_PATH_PREFIX'])
   source.save!
 end

backend/lib/tasks/sync_materials.rake

@@ -5,6 +5,7 @@ namespace :materials do
     message = [
       "materials:sync imported=#{ result.imported }",
       "updated=#{ result.updated }",
+      "unchanged=#{ result.unchanged }",
       "suppressed=#{ result.suppressed }",
       "failed=#{ result.failed }"
     ].join(' ')

backend/spec/models/material_spec.rb

@@ -0,0 +1,19 @@
+require 'rails_helper'
+
+RSpec.describe Material, type: :model do
+  let(:user) { create(:user, :member) }
+
+  it 'allows only material source kinds, not suppression prefix kinds' do
+    material = described_class.new(url: 'https://example.com/material',
+                                   source_kind: 'google_drive_path_prefix',
+                                   source_path: '素材/危険',
+                                   created_by_user: user,
+                                   updated_by_user: user)
+
+    expect(material).not_to be_valid
+    expect(material.errors[:source_kind]).to be_present
+
+    material.source_kind = 'google_drive_path'
+    expect(material).to be_valid
+  end
+end

backend/spec/requests/materials_spec.rb

@@ -64,27 +64,36 @@ RSpec.describe 'Materials API', type: :request do
         'name' => 'material_index_b',
         'category' => 'material'
       )
-      expect(row['created_by_user']).to include(
-        'id' => member_user.id,
-        'name' => member_user.name
-      )
       expect(row['content_type']).to eq('image/png')
+      expect(row['media_kind']).to eq('image')
     end
 
-    it 'filters materials by tag_id' do
+    it 'filters materials by q' do
-      get '/materials', params: { tag_id: material_a.tag_id }
+      get '/materials', params: { q: 'material_index_a' }
 
       expect(response).to have_http_status(:ok)
       expect(json['count']).to eq(1)
       expect(response_materials.map { |m| m['id'] }).to eq([material_a.id])
     end
 
-    it 'filters materials by parent_id' do
+    it 'filters materials by tag_state' do
-      get '/materials', params: { parent_id: material_a.id }
+      untagged =
+          build_material(tag: nil, user: member_user,
+                         file: dummy_upload(filename: 'untagged.png'))
+
+      get '/materials', params: { tag_state: 'untagged' }
 
       expect(response).to have_http_status(:ok)
       expect(json['count']).to eq(1)
-      expect(response_materials.map { |m| m['id'] }).to eq([material_b.id])
+      expect(response_materials.map { |m| m['id'] }).to eq([untagged.id])
+    end
+
+    it 'filters materials by media_kind' do
+      get '/materials', params: { media_kind: 'image' }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(2)
+      expect(response_materials.map { |m| m['media_kind'] }).to all(eq('image'))
     end
 
     it 'paginates and keeps total count' do
@@ -104,6 +113,68 @@ RSpec.describe 'Materials API', type: :request do
       expect(response_materials.size).to eq(1)
       expect(response_materials.first['id']).to eq(material_b.id)
     end
+
+    it 'filters by descendant tags and returns stable parent tag groups' do
+      root =
+          Tag.create!(tag_name: TagName.create!(name: 'material_scope_root'),
+                      category: :material)
+      child_b =
+          Tag.create!(tag_name: TagName.create!(name: 'material_scope_b'),
+                      category: :material)
+      child_a =
+          Tag.create!(tag_name: TagName.create!(name: 'material_scope_a'),
+                      category: :material)
+      deprecated =
+          Tag.create!(tag_name: TagName.create!(name: 'material_scope_old'),
+                      category: :material,
+                      deprecated_at: Time.current)
+      grandchild =
+          Tag.create!(tag_name: TagName.create!(name: 'material_scope_grandchild'),
+                      category: :material)
+      root_material =
+          build_material(tag: root, user: member_user,
+                         file: dummy_upload(filename: 'root.png'))
+      child_a_material =
+          build_material(tag: child_a, user: member_user,
+                         file: dummy_upload(filename: 'child_a.png'))
+      grandchild_material =
+          build_material(tag: grandchild, user: member_user,
+                         file: dummy_upload(filename: 'grandchild.png'))
+
+      TagImplication.create!(parent_tag: root, tag: child_b)
+      TagImplication.create!(parent_tag: root, tag: child_a)
+      TagImplication.create!(parent_tag: child_b, tag: deprecated)
+      TagImplication.create!(parent_tag: deprecated, tag: grandchild)
+
+      get '/materials',
+          params: { tag_id: root.id, include_descendants: '1',
+                    group_by: 'parent_tag', sort: 'id', direction: 'asc' }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_materials.map { |m| m['id'] })
+        .to include(root_material.id, child_a_material.id, grandchild_material.id)
+      expect(json['tag_scope']).to eq(
+        'tag' => {
+          'id' => root.id,
+          'name' => 'material_scope_root',
+          'category' => 'material'
+        },
+        'include_descendants' => true
+      )
+      expect(json['groups'].map { |group| group.dig('tag', 'name') })
+        .to eq(['material_scope_a', 'material_scope_b', 'material_scope_root'])
+      expect(json['groups'].find { |group| group.dig('tag', 'id') == child_b.id }
+        .fetch('material_ids')).to eq([grandchild_material.id])
+    end
+
+    it 'returns nil tag_scope when tag_id is unknown' do
+      get '/materials', params: { tag_id: 999_999, group_by: 'parent_tag' }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['tag_scope']).to be_nil
+      expect(json['groups']).to eq([])
+      expect(response_materials).to eq([])
+    end
   end
 
   describe 'GET /materials/:id' do
@@ -528,9 +599,8 @@ RSpec.describe 'Materials API', type: :request do
       expect(response.body.b).not_to include('素材/b.png'.b)
     end
 
-    it 'does not include suppressed materials' do
+    it 'does not include disabled export items' do
-      material_b.update!(file_suppressed_at: Time.current,
+      material_b.material_export_items.first.update!(enabled: false)
-                         file_suppression_reason: 'copyright_high_risk')
 
       get '/materials/download.zip', params: { profile: 'legacy_drive' }
 
@@ -540,62 +610,78 @@ RSpec.describe 'Materials API', type: :request do
     end
   end
 
-  describe 'PATCH /materials/:id/suppress_file' do
+  describe 'GET /materials/versions' do
     let!(:tag) do
-      Tag.create!(tag_name: TagName.create!(name: 'material_suppress'), category: :material)
+      Tag.create!(tag_name: TagName.create!(name: 'material_history'), category: :material)
     end
     let!(:material) do
-      build_material(tag:, user: member_user, file: dummy_upload(filename: 'suppress.png'))
+      build_material(tag:, user: member_user, file: dummy_upload(filename: 'history.png'))
     end
 
-    it 'allows admin to suppress a file and records a suppress version' do
+    it 'returns material versions in reverse chronological order' do
-      sign_in_as(admin_user)
+      MaterialVersionRecorder.record!(material:, event_type: :create,
+                                      created_by_user: member_user)
+      material.update!(url: 'https://example.com/history')
+      MaterialVersionRecorder.record!(material:, event_type: :update,
+                                      created_by_user: admin_user)
+
+      get '/materials/versions', params: { material_id: material.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(2)
+      versions = json.fetch('versions')
+      expect(versions.map { |v| v['version_no'] }).to eq([2, 1])
+      expect(versions.first).to include(
+        'material_id' => material.id,
+        'event_type' => 'update',
+        'tag_name' => 'material_history',
+        'file_filename' => 'history.png',
+        'url' => 'https://example.com/history'
+      )
+      expect(versions.first['created_by_user']).to include('id' => admin_user.id)
+    end
+
+    it 'filters material versions by tag and event_type' do
       MaterialVersionRecorder.record!(material:, event_type: :create,
                                       created_by_user: member_user)
 
-      expect do
+      get '/materials/versions', params: {
-        patch "/materials/#{ material.id }/suppress_file",
+        tag: 'material_history',
-              params: { reason: 'copyright_high_risk' }
+        event_type: 'create'
-      end.to change(MaterialVersion, :count).by(1)
+      }
 
       expect(response).to have_http_status(:ok)
+      expect(json.fetch('versions').map { |v| v['material_id'] }).to include(material.id)
+      expect(json.fetch('versions').map { |v| v['event_type'] }).to all(eq('create'))
+    end
+  end
 
-      material.reload
+  describe 'material sync suppressions' do
-      expect(material.file_suppressed_at).to be_present
+    it 'requires member permission for index' do
-      expect(material.file_suppressed_by_user).to eq(admin_user)
+      sign_out
-      expect(material.file_suppression_reason).to eq('copyright_high_risk')
+
-      expect(material.material_versions.order(:version_no).last.event_type).to eq('suppress')
+      get '/materials/suppressions'
-      expect(json['file']).to be_nil
+
-      expect(json['file_suppressed_at']).to be_present
+      expect(response).to have_http_status(:unauthorized)
     end
 
-    it 'purges blob when purge=true is requested' do
+    it 'creates source suppression as member' do
-      sign_in_as(admin_user)
-      old_blob_id = material.file.blob.id
-      MaterialVersionRecorder.record!(material:, event_type: :create,
-                                      created_by_user: member_user)
-
-      expect do
-        patch "/materials/#{ material.id }/suppress_file",
-              params: { reason: 'copyright_takedown', purge: '1' }
-      end.to have_enqueued_job(ActiveStorage::PurgeJob)
-
-      expect(response).to have_http_status(:ok)
-
-      version = material.material_versions.order(:version_no).last
-      expect(version.event_type).to eq('suppress')
-      expect(version.file_blob_id).to eq(old_blob_id)
-      expect(version.file_filename).to eq('suppress.png')
-      expect(version.file_sha256).to be_present
-    end
-
-    it 'rejects member suppression' do
       sign_in_as(member_user)
 
-      patch "/materials/#{ material.id }/suppress_file",
+      expect do
-            params: { reason: 'copyright_high_risk' }
+        post '/materials/suppressions', params: {
+          source_kind: 'google_drive_path_prefix',
+          drive_path: '伊地知ニジカ/危険素材',
+          reason: 'copyright_high_risk'
+        }
+      end.to change(MaterialSyncSuppression, :count).by(1)
 
-      expect(response).to have_http_status(:forbidden)
+      expect(response).to have_http_status(:created)
+      expect(json).to include(
+        'source_kind' => 'google_drive_path_prefix',
+        'drive_path' => '伊地知ニジカ/危険素材',
+        'normalized_source_key' => 'google_drive_path_prefix:伊地知ニジカ/危険素材'
+      )
     end
   end
 

backend/spec/requests/tags_spec.rb

@@ -581,6 +581,58 @@ RSpec.describe 'Tags API', type: :request do
         expect(response).to have_http_status(:ok)
         expect(wiki_page.reload.wiki_versions.count).to eq(before_wiki_version_count)
       end
+
+      it 'full update で旧名 alias が残った tag を PATCH で旧名へ戻せる' do
+        put "/tags/#{ tag.id }", params: {
+          name: 'patch_roundtrip_target',
+          category: 'general',
+          aliases: 'unko',
+          parent_tags: '',
+          deprecated: '0',
+        }
+
+        expect(response).to have_http_status(:ok)
+        expect(TagName.find_by!(name: 'spec_tag').canonical).to eq(tag.reload.tag_name)
+
+        patch "/tags/#{ tag.id }", params: { name: 'spec_tag' }
+
+        expect(response).to have_http_status(:ok)
+
+        tag.reload
+
+        expect(tag.name).to eq('spec_tag')
+        expect(tag.tag_name.canonical_id).to be_nil
+        expect(TagName.find_by!(name: 'patch_roundtrip_target').canonical).to eq(tag.tag_name)
+      end
+
+      it '別 tag の正規名には変更できない' do
+        wiki_page =
+            Wiki::Commit.create_content!(
+                tag_name: tag.tag_name,
+                body: 'patch collision wiki',
+                created_by_user: member_user,
+                message: 'init')
+
+        patch "/tags/#{ tag.id }", params: { name: 'unknown' }
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json.fetch('errors')).to include(
+          'name' => ['その名前は既に使はれてゐます．']
+        )
+
+        expect(tag.reload.name).to eq('spec_tag')
+        expect(tag.tag_name.aliases.map(&:name)).to contain_exactly('unko')
+        expect(wiki_page.reload.tag_name).to eq(tag.tag_name)
+      end
+
+      it 'system tag の name は変更できない' do
+        system_tag = Tag.bot
+
+        patch "/tags/#{ system_tag.id }", params: { name: 'patch_system_tag_renamed' }
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(system_tag.reload.name).to eq('bot操作')
+      end
     end
   end
 
@@ -1029,6 +1081,42 @@ RSpec.describe 'Tags API', type: :request do
         expect(versions.second.created_by_user_id).to eq(member_user.id)
       end
 
+      it '同じ tag の旧 alias へ戻しても rename できる' do
+        put "/tags/#{ tag.id }", params: {
+          name: 'put_roundtrip_b',
+          category: 'general',
+          aliases: 'unko',
+          parent_tags: '',
+          deprecated: '0',
+        }
+
+        expect(response).to have_http_status(:ok)
+
+        put "/tags/#{ tag.id }", params: {
+          name: 'spec_tag',
+          category: 'general',
+          aliases: 'unko',
+          parent_tags: '',
+          deprecated: '0',
+        }
+
+        expect(response).to have_http_status(:ok)
+
+        tag.reload
+
+        expect(tag.name).to eq('spec_tag')
+        expect(TagName.find_by!(name: 'put_roundtrip_b').canonical).to eq(tag.tag_name)
+        expect(tag.tag_name.aliases.map(&:name)).to contain_exactly('put_roundtrip_b', 'unko')
+        expect(tag.tag_name.aliases.map(&:name)).not_to include('spec_tag')
+        expect(alias_tn.reload.canonical).to eq(tag.tag_name)
+
+        version = tag.tag_versions.order(:version_no).last
+
+        expect(version.event_type).to eq('update')
+        expect(version.name).to eq('spec_tag')
+        expect(version.aliases.split).to contain_exactly('put_roundtrip_b', 'unko')
+      end
+
       it 'parent tag の snapshot も作成する' do
         old_parent = Tag.create!(
           tag_name: TagName.create!(name: 'put_snapshot_old_parent'),
@@ -1153,6 +1241,48 @@ RSpec.describe 'Tags API', type: :request do
         )
       end
 
+      it 'wiki を持つ tag を旧 alias へ戻しても wiki を新 canonical へ移す' do
+        wiki_page =
+            Wiki::Commit.create_content!(
+                tag_name: tag.tag_name,
+                body: 'wiki body before',
+                created_by_user: member_user,
+                message: 'init')
+
+        expect {
+          put "/tags/#{ tag.id }", params: {
+            name: 'put_wiki_roundtrip_b',
+            category: 'general',
+            aliases: 'unko',
+            parent_tags: '',
+            deprecated: '0',
+          }
+
+          put "/tags/#{ tag.id }", params: {
+            name: 'spec_tag',
+            category: 'general',
+            aliases: 'unko',
+            parent_tags: '',
+            deprecated: '0',
+          }
+        }
+            .to change(TagVersion, :count).by(3)
+            .and change(WikiVersion, :count).by(2)
+
+        expect(response).to have_http_status(:ok)
+
+        tag.reload
+
+        expect(wiki_page.reload.tag_name).to eq(tag.tag_name)
+        expect(TagName.find_by!(name: 'put_wiki_roundtrip_b').wiki_page).to be_nil
+        expect(TagName.find_by!(name: 'put_wiki_roundtrip_b').canonical).to eq(tag.tag_name)
+
+        versions = wiki_page.wiki_versions.order(:version_no).last(2)
+
+        expect(versions.map(&:event_type)).to eq(['update', 'update'])
+        expect(versions.map(&:title)).to eq(['put_wiki_roundtrip_b', 'spec_tag'])
+      end
+
       it '別名を他 tag から奪った場合、奪はれた側の tag version も作成する' do
         old_owner = Tag.create!(
           tag_name: TagName.create!(name: 'put_alias_old_owner'),
@@ -1191,6 +1321,48 @@ RSpec.describe 'Tags API', type: :request do
         expect(old_owner_versions.second.aliases.split).not_to include('put_stolen_alias')
       end
 
+      it '別 tag の alias 名を rename で奪へる' do
+        old_owner = Tag.create!(
+          tag_name: TagName.create!(name: 'put_alias_collision_owner'),
+          category: :general
+        )
+        stolen_alias = TagName.create!(
+          name: 'put_alias_collision_name',
+          canonical: old_owner.tag_name
+        )
+        wiki_page =
+            Wiki::Commit.create_content!(
+                tag_name: tag.tag_name,
+                body: 'put collision wiki',
+                created_by_user: member_user,
+                message: 'init')
+
+        put "/tags/#{ tag.id }", params: {
+          name: 'put_alias_collision_name',
+          category: 'general',
+          aliases: 'unko',
+          parent_tags: '',
+          deprecated: '0',
+        }
+
+        expect(response).to have_http_status(:ok)
+
+        tag.reload
+        old_owner.reload
+        stolen_alias.reload
+
+        expect(tag.name).to eq('put_alias_collision_name')
+        expect(stolen_alias.canonical_id).to be_nil
+        expect(TagName.find_by!(name: 'spec_tag').canonical).to eq(tag.tag_name)
+        expect(old_owner.tag_name.aliases.map(&:name)).not_to include('put_alias_collision_name')
+
+        old_owner_versions = old_owner.tag_versions.order(:version_no)
+
+        expect(old_owner_versions.last.event_type).to eq('update')
+        expect(old_owner_versions.last.aliases.split).not_to include('put_alias_collision_name')
+        expect(wiki_page.reload.tag_name).to eq(tag.tag_name)
+      end
+
       it 'parent_tags に指定すると循環する tag は 422 にする' do
         pending '#332 で対応予定'
 

backend/spec/services/material_file_sha256_spec.rb

@@ -0,0 +1,23 @@
+require 'rails_helper'
+
+RSpec.describe MaterialFileSha256 do
+  describe '.metadata_sha256' do
+    it 'reads sha256 from Hash metadata' do
+      blob = instance_double(ActiveStorage::Blob, metadata: { 'sha256' => 'abc123' })
+
+      expect(described_class.metadata_sha256(blob)).to eq('abc123')
+    end
+
+    it 'reads sha256 from JSON string metadata' do
+      blob = instance_double(ActiveStorage::Blob, metadata: '{"sha256":"abc123"}')
+
+      expect(described_class.metadata_sha256(blob)).to eq('abc123')
+    end
+
+    it 'returns nil for invalid metadata' do
+      blob = instance_double(ActiveStorage::Blob, metadata: '{')
+
+      expect(described_class.metadata_sha256(blob)).to be_nil
+    end
+  end
+end

backend/spec/services/material_sync_importer_spec.rb

@@ -0,0 +1,128 @@
+require 'rails_helper'
+
+RSpec.describe MaterialSyncImporter do
+  let(:user) { create(:user, :member) }
+  let(:tag) { Tag.create!(tag_name: TagName.create!(name: 'sync_tag'), category: :material) }
+
+  def tempfile_for body
+    Tempfile.new(['material-sync-importer', '.png']).tap do |file|
+      file.binmode
+      file.write(body)
+      file.rewind
+    end
+  end
+
+  it 'creates an untagged material from a sync candidate with file_downloader' do
+    result =
+        described_class.import!(
+            source_kind: 'google_drive_file',
+            source_path: '素材/a.png',
+            source_file_id: 'drive-file-a',
+            normalized_source_key: 'google_drive_file:drive-file-a',
+            filename: 'a.png',
+            content_type: 'image/png',
+            file_sha256: Digest::SHA256.hexdigest('sync-body'),
+            file_downloader: -> { tempfile_for('sync-body') },
+            export_path: '素材/a.png',
+            tag: nil,
+            url: nil,
+            created_by_user: user,
+            updated_by_user: user)
+
+    material = result.material.reload
+    expect(result.action).to eq(:imported)
+    expect(material.tag).to be_nil
+    expect(material.url).to be_nil
+    expect(material.file).to be_attached
+    expect(material.file.blob.filename.to_s).to eq('a.png')
+    expect(material.material_export_items.first.export_path).to eq('素材/a.png')
+  end
+
+  it 'does not clear a human-assigned tag or URL on existing Drive sync' do
+    material =
+        Material.create!(tag:, url: 'https://example.com/human',
+                         source_kind: 'google_drive_file',
+                         source_path: '素材/a.png',
+                         source_file_id: 'drive-file-a',
+                         created_by_user: user,
+                         updated_by_user: user)
+    material.file.attach(
+        io: StringIO.new('same-body'),
+        filename: 'a.png',
+        content_type: 'image/png')
+    material.file.blob.metadata['sha256'] = Digest::SHA256.hexdigest('same-body')
+    material.file.blob.save!
+    MaterialExportItem.create!(material:,
+                               profile: 'legacy_drive',
+                               export_path: '素材/a.png',
+                               created_by_user: user)
+
+    result =
+        described_class.import!(
+            source_kind: 'google_drive_file',
+            source_path: '素材/a.png',
+            source_file_id: 'drive-file-a',
+            filename: 'a.png',
+            content_type: 'image/png',
+            file_sha256: Digest::SHA256.hexdigest('same-body'),
+            export_path: '素材/a.png',
+            tag: nil,
+            url: nil,
+            updated_by_user: user)
+
+    expect(result.action).to eq(:unchanged)
+    expect(material.reload.tag).to eq(tag)
+    expect(material.url).to eq('https://example.com/human')
+  end
+
+  it 'suppresses a Google Drive candidate by relative path prefix' do
+    MaterialSyncSuppression.create!(source_kind: 'google_drive_path_prefix',
+                                    drive_path: '素材/危険',
+                                    reason: 'copyright_high_risk',
+                                    created_by_user: user)
+
+    result =
+        described_class.import!(
+            source_kind: 'google_drive_file',
+            source_path: '素材/危険/a.png',
+            source_file_id: 'drive-file-b',
+            filename: 'a.png',
+            content_type: 'image/png',
+            file_sha256: Digest::SHA256.hexdigest('blocked-body'),
+            file_downloader: -> { tempfile_for('blocked-body') },
+            export_path: '素材/危険/a.png',
+            updated_by_user: user)
+
+    expect(result.action).to eq(:suppressed)
+    expect(result.suppression.normalized_source_key)
+      .to eq('google_drive_path_prefix:素材/危険')
+    expect(Material.find_by(source_file_id: 'drive-file-b')).to be_nil
+  end
+
+  it 'rechecks import blocks after downloaded file sha256 is known' do
+    MaterialImportBlock.create!(match_kind: 'sha256',
+                                sha256: Digest::SHA256.hexdigest('blocked-body'),
+                                reason: 'copyright_high_risk',
+                                created_by_user: user)
+    blob_count = ActiveStorage::Blob.count
+
+    expect do
+      result =
+          described_class.import!(
+              source_kind: 'google_drive_file',
+              source_path: '素材/blocked.png',
+              source_file_id: 'drive-file-blocked',
+              filename: 'blocked.png',
+              content_type: 'image/png',
+              file_downloader: -> { tempfile_for('blocked-body') },
+              export_path: '素材/blocked.png',
+              updated_by_user: user)
+
+      expect(result.action).to eq(:suppressed)
+      expect(result.suppression.reason).to eq('copyright_high_risk')
+    end.not_to change(Material, :count)
+
+    expect(ActiveStorage::Blob.count).to eq(blob_count)
+    expect(Material.find_by(source_file_id: 'drive-file-blocked')).to be_nil
+  end
+end

backend/spec/services/material_sync_runner_spec.rb

@@ -0,0 +1,89 @@
+require 'rails_helper'
+
+RSpec.describe MaterialSyncRunner do
+  let(:user) { create(:user, :member) }
+  let(:source) do
+    MaterialSyncSource.create!(
+        name: 'Drive source',
+        source_kind: 'google_drive_path',
+        source_file_id: 'folder-123',
+        profile: 'legacy_drive',
+        created_by_user: user,
+        updated_by_user: user)
+  end
+  let(:drive_client) { instance_double(GoogleDrive::ApiClient) }
+
+  describe '#sync!' do
+    it 'imports google drive path candidates as they are yielded' do
+      first_entry = { id: 'file-1',
+                      name: 'a.png',
+                      mime_type: 'image/png',
+                      relative_path: '素材/a.png',
+                      sha256_checksum: 'sha-a',
+                      web_view_link: 'https://drive.google.com/file/d/file-1/view',
+                      web_content_link: nil }
+      second_entry = { id: 'file-2',
+                       name: 'b.png',
+                       mime_type: 'image/png',
+                       relative_path: '素材/b.png',
+                       sha256_checksum: 'sha-b',
+                       web_view_link: 'https://drive.google.com/file/d/file-2/view',
+                       web_content_link: nil }
+      yielded = []
+
+      allow(GoogleDrive::ApiClient).to receive(:new).and_return(drive_client)
+      allow(drive_client).to receive(:each_material_file_under_folder) do |folder_id, &block|
+        expect(folder_id).to eq('folder-123')
+        block.call(first_entry)
+        expect(yielded).to eq(['素材/a.png'])
+        block.call(second_entry)
+      end
+      allow(MaterialSyncImporter).to receive(:import!) do |candidate|
+        yielded << candidate.fetch(:source_path)
+        instance_double(MaterialSyncImporter::Result,
+                        action: yielded.last == '素材/a.png' ? :imported : :updated)
+      end
+
+      result = described_class.new(source).sync!
+
+      expect(yielded).to eq(['素材/a.png', '素材/b.png'])
+      expect(result.imported).to eq(1)
+      expect(result.updated).to eq(1)
+      expect(result.unchanged).to eq(0)
+      expect(source.reload.last_synced_at).to be_present
+    end
+
+    it 'logs google drive path progress at first item and summary' do
+      entry = { id: 'file-1',
+                name: 'a.png',
+                mime_type: 'image/png',
+                relative_path: '素材/a.png',
+                sha256_checksum: 'sha-a',
+                web_view_link: 'https://drive.google.com/file/d/file-1/view',
+                web_content_link: nil }
+      logged = []
+
+      allow(GoogleDrive::ApiClient).to receive(:new).and_return(drive_client)
+      allow(drive_client).to receive(:each_material_file_under_folder) do |_folder_id, &block|
+        block.call(entry)
+      end
+      allow(MaterialSyncImporter).to receive(:import!)
+        .and_return(instance_double(MaterialSyncImporter::Result, action: :imported))
+      allow(Rails.logger).to receive(:info) { |message| logged << JSON.parse(message) }
+
+      described_class.new(source).sync!
+
+      progress_logs = logged.select { |row| row['folder_id'] == 'folder-123' }
+      expect(progress_logs.map { |row| row['progress'] }).to eq(['scan', 'summary'])
+      expect(progress_logs.last).to include(
+          'material_sync_source_id' => source.id,
+          'material_sync_source_name' => 'Drive source',
+          'scanned_count' => 1,
+          'imported' => 1,
+          'updated' => 0,
+          'unchanged' => 0,
+          'suppressed' => 0,
+          'failed' => 0)
+    end
+  end
+end

frontend/src/App.tsx

@@ -75,7 +75,6 @@ const RouteTransitionWrapper = ({ user, setUser }: {
 	    <Route path="suppressions" element={<MaterialSyncSuppressionsPage/>}/>
 	    <Route path=":id" element ={<MaterialDetailPage/>}/>
 	  </Route>
-	  {/* <Route path="/materials/search" element={<MaterialSearchPage/>}/> */}
 	  <Route path="/wiki" element={<WikiSearchPage/>}/>
 	  <Route path="/wiki/:title" element={<WikiDetailPage/>}/>
 	  <Route path="/wiki/new" element={<WikiNewPage user={user}/>}/>

frontend/src/components/MaterialSidebar.tsx

@@ -1,28 +1,43 @@
-import { Fragment, useEffect, useRef, useState } from 'react'
 import { useQuery } from '@tanstack/react-query'
+import { useEffect, useRef, useState } from 'react'
 import { useLocation, useNavigate } from 'react-router-dom'
 
-import TagLink from '@/components/TagLink'
 import SidebarComponent from '@/components/layout/SidebarComponent'
-import { materialsKeys } from '@/lib/queryKeys'
+import TagLink from '@/components/TagLink'
 import { fetchMaterialTagTree, parseMaterialFilter } from '@/lib/materials'
+import { materialsKeys } from '@/lib/queryKeys'
+import { cn } from '@/lib/utils'
 
-import type { Dispatch, FC, ReactNode, SetStateAction } from 'react'
+import type { CSSProperties, Dispatch, FC, ReactNode, SetStateAction } from 'react'
 
 import type { MaterialFilter, MaterialSidebarTag, Tag } from '@/types'
 
-const FILTERS: MaterialFilter[] = ['present', 'missing', 'any']
+const FILTERS: MaterialFilter[] = ['missing', 'present', 'any']
+const FILTER_LABELS: Record<MaterialFilter, string> = { present: '有', missing: '無', any: '全' }
 
-const FILTER_LABELS: Record<MaterialFilter, string> = {
+
-    present: '素材あり',
+const px = (value: string): number => {
-    missing: '素材なし',
+  const parsed = Number.parseFloat (value)
-    any:     'すべて'}
+  return Number.isFinite (parsed) ? parsed : 0
+}
+
+
+const verticalChrome = (el: HTMLElement): number => {
+  const style = window.getComputedStyle (el)
+
+  return (
+      px (style.paddingTop)
+      + px (style.paddingBottom)
+      + px (style.borderTopWidth)
+      + px (style.borderBottomWidth))
+}
 
 
 const setChildrenById = (
     tags:     MaterialSidebarTag[],
     targetId: number,
-    children: MaterialSidebarTag[]): MaterialSidebarTag[] => (
+    children: MaterialSidebarTag[],
+): MaterialSidebarTag[] => (
     tags.map (tag => {
       if (tag.id === targetId)
 	return { ...tag, children }
@@ -35,8 +50,11 @@ const setChildrenById = (
 
 
 const materialPath = (
-    tagName: string,
+    tagId: number,
-    materialFilter: MaterialFilter): string => `/materials?q=${ encodeURIComponent (tagName) }&material_filter=${ materialFilter }`
+    materialFilter: MaterialFilter,
+): string =>
+    `/materials?tag_id=${ tagId }&include_descendants=1&group_by=parent_tag`
+    + `&material_filter=${ materialFilter }`
 
 
 const sidebarTagToTag = (tag: MaterialSidebarTag): Tag => ({
@@ -55,33 +73,43 @@ const sidebarTagToTag = (tag: MaterialSidebarTag): Tag => ({
     matchedAlias:   null })
 
 
+const tagSelectionShellClass = (selected: boolean): string =>
+    cn (selected
+	? ['rounded-md border border-sky-500 bg-sky-50 px-2 py-1 text-sky-700',
+	   'dark:border-sky-400 dark:bg-sky-950 dark:text-sky-100']
+	: 'px-2 py-1')
+
+
 const updateMaterialFilterQuery = (
     pathname: string,
     locationSearch: string,
     navigate: ReturnType<typeof useNavigate>,
-    materialFilter: MaterialFilter) => {
+    materialFilter: MaterialFilter,
-    const qs = new URLSearchParams (locationSearch)
+) => {
-    qs.set ('material_filter', materialFilter)
+  const qs = new URLSearchParams (locationSearch)
-    navigate (`${ pathname }${ qs.toString () ? `?${ qs.toString () }` : '' }`)
+  qs.set ('material_filter', materialFilter)
+  navigate (`${ pathname }${ qs.toString () ? `?${ qs.toString () }` : '' }`)
 }
 
 
-const MaterialFilterButtons: FC<{
+const MaterialFilterButtons: FC<{ materialFilter: MaterialFilter
-    materialFilter: MaterialFilter
+				  onChange:       (materialFilter: MaterialFilter) => void }> = (
-    onChange:       (materialFilter: MaterialFilter) => void
+    { materialFilter, onChange },
-}> = ({ materialFilter, onChange }) => (
+) => (
-    <div className="flex flex-wrap gap-2">
+    <div className="flex flex-wrap gap-2 justify-end md:justify-start flex-center">
+      <label className="my-auto text-sm font-bold">素材：</label>
       {FILTERS.map (value => (
 	  <button
 	      key={value}
 	      type="button"
 	      onClick={() => onChange (value)}
-	      className={`rounded-full border px-3 py-1 text-sm ${
+	      className={cn (
-		  materialFilter === value
+		  'rounded-full border px-3 py-1 text-sm',
-		  ? 'border-sky-500 bg-sky-50 text-sky-700 dark:border-sky-400 ' +
+		  (materialFilter === value
-		    'dark:bg-sky-950 dark:text-sky-100'
+		   ? ['border-sky-500 bg-sky-50 text-sky-700 dark:border-sky-400',
-		  : 'border-neutral-300 bg-white text-neutral-700 dark:border-stone-700 ' +
+		      'dark:bg-sky-950 dark:text-sky-100']
-		    'dark:bg-stone-900 dark:text-stone-200' }`}>
+		   : ['border-neutral-300 bg-white text-neutral-700 dark:border-stone-700',
+		      'dark:bg-stone-900 dark:text-stone-200']))}>
 	    {FILTER_LABELS[value]}
 	  </button>))}
     </div>)
@@ -89,12 +117,14 @@ const MaterialFilterButtons: FC<{
 
 const MaterialTreeNode: FC<{
     materialFilter: MaterialFilter
+    selectedTagId:  number | null
     nestLevel?:     number
     onChildren:     (tagId: number, children: MaterialSidebarTag[]) => void
     openTags:       Record<number, boolean>
     setOpenTags:    Dispatch<SetStateAction<Record<number, boolean>>>
     tag:            MaterialSidebarTag
-}> = ({ materialFilter, nestLevel = 0, onChildren, openTags, setOpenTags, tag }) => {
+}> = ({ materialFilter, nestLevel = 0, onChildren, openTags, selectedTagId,
+	 setOpenTags, tag }) => {
   const open = Boolean (openTags[tag.id])
   const { data } = useQuery ({
       queryKey: materialsKeys.tree ({ parentId: tag.id, materialFilter }),
@@ -107,10 +137,10 @@ const MaterialTreeNode: FC<{
   }, [data, onChildren, open, tag.children.length, tag.id])
 
   return (
-      <Fragment>
+      <>
 	<li>
-	  <div className="flex">
+	  <div className="flex flex-center">
-	    <div className="flex-none w-4">
+	    <div className="flex-none w-4 my-auto">
 	      {tag.hasChildren && (
 		  <button
 		      type="button"
@@ -119,14 +149,17 @@ const MaterialTreeNode: FC<{
 		    {open ? <>&minus;</> : '+'}
 		  </button>)}
 	    </div>
-	    <div className="flex-1 truncate">
+	    <div className="min-w-0 flex-1 my-auto">
-	      <TagLink
+	      <div className={cn (tagSelectionShellClass (selectedTagId === tag.id),
-		  tag={sidebarTagToTag (tag)}
+				  'min-w-0 truncate')}>
-		  nestLevel={nestLevel}
+		<TagLink
-		  title={tag.name}
+		    tag={sidebarTagToTag (tag)}
-		  withCount={false}
+		    nestLevel={nestLevel}
-		  withWiki={false}
+		    title={tag.name}
-		  to={materialPath (tag.name, materialFilter)}/>
+		    withCount={false}
+		    withWiki={false}
+		    to={materialPath (tag.id, materialFilter)}/>
+	      </div>
 	    </div>
 	  </div>
 	</li>
@@ -138,23 +171,44 @@ const MaterialTreeNode: FC<{
 		      tag={child}
 		      nestLevel={nestLevel + 1}
 		      materialFilter={materialFilter}
+		      selectedTagId={selectedTagId}
 		      openTags={openTags}
 		      setOpenTags={setOpenTags}
 		      onChildren={onChildren}/>))}
 	    </ul>)}
-      </Fragment>)
+      </>)
 }
 
 
-const MobileMaterialTreeNode: FC<{
+const MobileMaterialTreeNode: FC<{ depth?: number
-    depth?:          number
+				   availableInlineSizePx?: number | null
-    materialFilter: MaterialFilter
+				   materialFilter: MaterialFilter
-    onChildren:     (tagId: number, children: MaterialSidebarTag[]) => void
+				   selectedTagId: number | null
-    openTags:       Record<number, boolean>
+				   onChildren: (tagId: number, children: MaterialSidebarTag[]) =>
-    setOpenTags:    Dispatch<SetStateAction<Record<number, boolean>>>
+						   void
-    tag:            MaterialSidebarTag
+				   openTags: Record<number, boolean>
-}> = ({ depth = 0, materialFilter, onChildren, openTags, setOpenTags, tag }) => {
+				   setOpenTags: Dispatch<SetStateAction<Record<number, boolean>>>
+				   tag: MaterialSidebarTag }> = (
+    {
+      depth = 0,
+      availableInlineSizePx = null,
+      materialFilter,
+      onChildren,
+      openTags,
+      selectedTagId,
+      setOpenTags,
+      tag,
+    },
+) => {
   const open = Boolean (openTags[tag.id])
+  const tagColumnRef = useRef<HTMLDivElement | null> (null)
+  const chipRef = useRef<HTMLDivElement | null> (null)
+  const buttonRef = useRef<HTMLButtonElement | null> (null)
+  const expansionSlotRef = useRef<HTMLDivElement | null> (null)
+  const expansionBorderRef = useRef<HTMLDivElement | null> (null)
+  const [tagChipInlineSizePx, setTagChipInlineSizePx] = useState<number | null> (null)
+  const [tagLinkInlineSizePx, setTagLinkInlineSizePx] = useState<number | null> (null)
+  const [childAvailableInlineSizePx, setChildAvailableInlineSizePx] = useState<number | null> (null)
   const { data } = useQuery ({
       queryKey: materialsKeys.tree ({ parentId: tag.id, materialFilter }),
       queryFn:  () => fetchMaterialTagTree ({ parentId: tag.id, materialFilter }),
@@ -165,50 +219,155 @@ const MobileMaterialTreeNode: FC<{
       onChildren (tag.id, data)
   }, [data, onChildren, open, tag.children.length, tag.id])
 
+  useEffect (() => {
+    const tagColumn = tagColumnRef.current
+    const chip = chipRef.current
+    if (!(tagColumn) || !(chip))
+      return
+
+    const updateTagInlineSize = () => {
+      const buttonHeight = buttonRef.current?.offsetHeight ?? 0
+      const gap = tag.hasChildren ? px (window.getComputedStyle (tagColumn).rowGap) : 0
+      const columnHeight =
+	  availableInlineSizePx == null
+	  ? tagColumn.clientHeight
+	  : Math.min (tagColumn.clientHeight, availableInlineSizePx)
+      const nextChipInlineSize = Math.max (24, columnHeight - buttonHeight - gap)
+      const nextLinkInlineSize = Math.max (
+	  16,
+	  nextChipInlineSize - verticalChrome (chip),
+      )
+
+      setTagChipInlineSizePx (prev => prev === nextChipInlineSize ? prev : nextChipInlineSize)
+      setTagLinkInlineSizePx (prev => prev === nextLinkInlineSize ? prev : nextLinkInlineSize)
+    }
+
+    updateTagInlineSize ()
+
+    const resizeObserver = new ResizeObserver (() => {
+      updateTagInlineSize ()
+    })
+
+    resizeObserver.observe (tagColumn)
+    resizeObserver.observe (chip)
+
+    if (buttonRef.current)
+      resizeObserver.observe (buttonRef.current)
+
+    return () => {
+      resizeObserver.disconnect ()
+    }
+  }, [availableInlineSizePx, open, tag.hasChildren, tag.children.length])
+
+  useEffect (() => {
+    const expansionSlot = expansionSlotRef.current
+    const expansionBorder = expansionBorderRef.current
+    if (!(expansionSlot) || !(expansionBorder))
+      return
+
+    const updateChildInlineSize = () => {
+      const base =
+	  availableInlineSizePx == null
+	  ? expansionSlot.clientHeight
+	  : availableInlineSizePx
+      const chrome = verticalChrome (expansionSlot) + verticalChrome (expansionBorder)
+      const nextInlineSize = Math.max (24, base - chrome)
+      setChildAvailableInlineSizePx (prev => prev === nextInlineSize ? prev : nextInlineSize)
+    }
+
+    updateChildInlineSize ()
+
+    const resizeObserver = new ResizeObserver (() => {
+      updateChildInlineSize ()
+    })
+
+    resizeObserver.observe (expansionSlot)
+    resizeObserver.observe (expansionBorder)
+
+    return () => {
+      resizeObserver.disconnect ()
+    }
+  }, [availableInlineSizePx, open, tag.children.length])
+
   return (
-      <div className="flex flex-row-reverse items-start gap-2">
+      <div className="flex h-full min-h-0 max-h-full flex-row-reverse items-start gap-2
-	<div className="flex flex-col items-center gap-1">
+		      overflow-hidden">
+	<div
+	    ref={tagColumnRef}
+	    className="flex h-full min-h-0 max-h-full flex-col items-center gap-1
+		       overflow-hidden">
 	  <div
-	      className="rounded-xl border border-stone-300 bg-white px-3 py-2 text-sm
+	      ref={chipRef}
-			 text-stone-900 shadow-sm dark:border-stone-700 dark:bg-stone-900
+	      className={cn (
-			 dark:text-stone-100"
+		  tagSelectionShellClass (selectedTagId === tag.id),
-	      style={{ writingMode: 'vertical-rl' }}>
+		  'box-border rounded-xl border px-3 py-2 text-sm shadow-sm',
+		  'min-h-0 overflow-hidden [max-inline-size:var(--tag-chip-inline-size)]',
+		  '[max-height:var(--tag-chip-inline-size)]',
+	      )}
+	      style={{
+		writingMode: 'vertical-rl',
+		'--tag-chip-inline-size': (
+		    tagChipInlineSizePx == null
+		    ? undefined
+		    : `${ tagChipInlineSizePx }px`),
+		'--tag-link-inline-size': (
+		    tagLinkInlineSizePx == null
+		    ? undefined
+		    : `${ tagLinkInlineSizePx }px`),
+	      } as CSSProperties}>
 	    <TagLink
 		tag={sidebarTagToTag (tag)}
 		title={tag.name}
 		withCount={false}
 		withWiki={false}
-		to={materialPath (tag.name, materialFilter)}/>
+		to={materialPath (tag.id, materialFilter)}
+		className="block overflow-hidden text-ellipsis whitespace-nowrap
+			   [max-inline-size:var(--tag-link-inline-size)]
+			   [max-height:var(--tag-link-inline-size)]"/>
 	  </div>
 	  {tag.hasChildren && (
 	      <button
+		  ref={buttonRef}
 		  type="button"
 		  onClick={() => setOpenTags (prev => ({ ...prev, [tag.id]: !prev[tag.id] }))}
-		  className="rounded-full border border-stone-300 bg-white px-2 py-0.5
+		  className="flex-none rounded-full border border-stone-300 bg-white
-			     text-sm text-stone-700 dark:border-stone-700
+			     px-2 py-0.5 text-sm text-stone-700 dark:border-stone-700
 			     dark:bg-stone-900 dark:text-stone-100">
 		{open ? <>&minus;</> : '+'}
 	      </button>)}
 	</div>
 	{open && tag.children.length > 0 && (
 	    <div
-		className="relative flex flex-row-reverse items-start gap-2 rounded-2xl border
+		ref={expansionSlotRef}
-			   border-stone-200 bg-stone-100/70 py-2 pl-2 pr-2 text-stone-900
+		className={cn (
-			   dark:border-stone-700 dark:bg-stone-900/70 dark:text-stone-100"
+		    'h-full min-h-0 max-h-full overflow-hidden box-border',
-		style={{ marginTop: `${ depth === 0 ? 1.25 : .75 }rem` }}>
+		    depth === 0 ? 'pt-5' : 'pt-3')}>
-	      <span
+	      <div
-		  aria-hidden="true"
+		  ref={expansionBorderRef}
-		  className="absolute -right-3 top-4 h-px w-3 bg-stone-300 dark:bg-stone-600"/>
+		  className="relative max-h-full overflow-hidden rounded-2xl border border-stone-200
-	      {tag.children.map (child => (
+			     bg-stone-100/70 py-2 pl-2 pr-2 text-stone-900
-		  <div key={child.id} className="relative">
+			     dark:border-stone-700 dark:bg-stone-900/70 dark:text-stone-100">
-		    <MobileMaterialTreeNode
+		<div className="flex h-full min-h-0 max-h-full flex-row-reverse items-start gap-2
-			tag={child}
+				overflow-hidden">
-			depth={depth + 1}
+		  <span
-			materialFilter={materialFilter}
+		      aria-hidden="true"
-			openTags={openTags}
+		      className="absolute -right-3 top-4 h-px w-3 bg-stone-300 dark:bg-stone-600"/>
-			setOpenTags={setOpenTags}
+		  {tag.children.map (child => (
-			onChildren={onChildren}/>
+		      <div
-		  </div>))}
+			  key={child.id}
+			  className="relative h-full min-h-0 max-h-full overflow-hidden">
+			<MobileMaterialTreeNode
+			    tag={child}
+			    depth={depth + 1}
+			    availableInlineSizePx={childAvailableInlineSizePx}
+			    materialFilter={materialFilter}
+			    selectedTagId={selectedTagId}
+			    openTags={openTags}
+			    setOpenTags={setOpenTags}
+			    onChildren={onChildren}/>
+		      </div>))}
+		</div>
+	      </div>
 	    </div>)}
       </div>)
 }
@@ -218,11 +377,14 @@ const MaterialSidebar: FC = () => {
   const location = useLocation ()
   const navigate = useNavigate ()
   const qs = new URLSearchParams (location.search)
-  const materialFilter = parseMaterialFilter (qs.get ('material_filter'), 'present')
+  const materialFilter = parseMaterialFilter (qs.get ('material_filter'), 'any')
+  const selectedTagId = Number (qs.get ('tag_id') ?? 0) || null
 
   const [desktopTags, setDesktopTags] = useState<MaterialSidebarTag[]> ([])
   const [openTags, setOpenTags] = useState<Record<number, boolean>> ({ })
   const mobileRailRef = useRef<HTMLDivElement | null> (null)
+  const [mobileAvailableInlineSizePx, setMobileAvailableInlineSizePx] =
+      useState<number | null> (null)
 
   const { data: rootTags = [], isLoading, isError } = useQuery ({
       queryKey: materialsKeys.tree ({ parentId: null, materialFilter }),
@@ -242,6 +404,29 @@ const MaterialSidebar: FC = () => {
     })
   }, [rootTags, materialFilter])
 
+  useEffect (() => {
+    const el = mobileRailRef.current
+    if (!(el))
+      return
+
+    const updateAvailableInlineSize = () => {
+      const nextInlineSize = Math.max (24, el.clientHeight)
+      setMobileAvailableInlineSizePx (prev => prev === nextInlineSize ? prev : nextInlineSize)
+    }
+
+    updateAvailableInlineSize ()
+
+    const resizeObserver = new ResizeObserver (() => {
+      updateAvailableInlineSize ()
+    })
+
+    resizeObserver.observe (el)
+
+    return () => {
+      resizeObserver.disconnect ()
+    }
+  }, [rootTags, materialFilter])
+
   const visibleRootTags = desktopTags.length > 0 ? desktopTags : rootTags
 
   const setChildren = (tagId: number, children: MaterialSidebarTag[]) => {
@@ -263,6 +448,7 @@ const MaterialSidebar: FC = () => {
 	      key={tag.id}
 	      tag={tag}
 	      materialFilter={materialFilter}
+	      selectedTagId={selectedTagId}
 	      openTags={openTags}
 	      setOpenTags={setOpenTags}
 	      onChildren={setChildren}/>)))
@@ -270,17 +456,23 @@ const MaterialSidebar: FC = () => {
   return (
       <>
 	<div className="border-b bg-stone-50 p-3 dark:border-stone-700 dark:bg-stone-950
-			dark:text-stone-100 md:hidden">
+			dark:text-stone-100 md:hidden flex h-[25dvh] min-h-0 flex-col
+			overflow-hidden">
 	  <MaterialFilterButtons
 	      materialFilter={materialFilter}
 	      onChange={handleFilterChange}/>
-	  <div ref={mobileRailRef} className="mt-3 overflow-x-auto">
+	  <div
-	    <div className="flex min-w-max flex-row-reverse gap-3 pb-1">
+	      ref={mobileRailRef}
+	      className="mt-3 min-h-0 flex-1 overflow-x-auto overflow-y-hidden">
+	    <div className="flex min-w-max flex-row-reverse items-start gap-3 pb-1 h-full
+			    min-h-0 max-h-full">
 	      {visibleRootTags.map (tag => (
 		  <MobileMaterialTreeNode
 		      key={tag.id}
 		      tag={tag}
+		      availableInlineSizePx={mobileAvailableInlineSizePx}
 		      materialFilter={materialFilter}
+		      selectedTagId={selectedTagId}
 		      openTags={openTags}
 		      setOpenTags={setOpenTags}
 		      onChildren={setChildren}/>))}

frontend/src/components/TagLink.tsx

@@ -28,11 +28,12 @@ type Props =
 
 
 const TagLink: FC<Props> = ({ tag,
-		   nestLevel = 0,
+			      nestLevel = 0,
-		   linkFlg   = true,
+			      linkFlg   = true,
-		   withWiki  = true,
+			      withWiki  = true,
-		   withCount = true,
+			      withCount = true,
-		   ...props }) => {
+			      className,
+			      ...props }) => {
   const spanClass = cn (
       `text-${ TAG_COLOUR[tag.category] }-${ LIGHT_COLOUR_SHADE }`,
       `dark:text-${ TAG_COLOUR[tag.category] }-${ DARK_COLOUR_SHADE }`)
@@ -105,7 +106,7 @@ const TagLink: FC<Props> = ({ tag,
 	    </span>)}
 	{tag.matchedAlias != null && (
 	    <>
-	      <span className={spanClass} {...props}>
+	      <span className={cn (spanClass, className)} {...props}>
 		{tag.matchedAlias}
 	      </span>
 	      <> → </>
@@ -114,12 +115,12 @@ const TagLink: FC<Props> = ({ tag,
 	 ? (
 	    <PrefetchLink
 		to={`/posts?${ (new URLSearchParams ({ tags: tag.name })).toString () }`}
-		className={linkClass}
+		className={cn (linkClass, className)}
 		{...props}>
 	      {tag.name}
 	    </PrefetchLink>)
 	 : (
-	    <span className={spanClass}
+	    <span className={cn (spanClass, className)}
 		  {...props}>
 	      {tag.name}
 	    </span>)}

frontend/src/components/TopNav.tsx

@@ -7,30 +7,36 @@ import Separator from '@/components/MenuSeparator'
 import PrefetchLink from '@/components/PrefetchLink'
 import TopNavUser from '@/components/TopNavUser'
 import { WikiIdBus } from '@/lib/eventBus/WikiIdBus'
-import { tagsKeys, wikiKeys } from '@/lib/queryKeys'
+import { materialsKeys, tagsKeys, wikiKeys } from '@/lib/queryKeys'
 import { fetchTag, fetchTagByName } from '@/lib/tags'
+import { fetchMaterial } from '@/lib/materials'
 import { cn } from '@/lib/utils'
 import { fetchWikiPage } from '@/lib/wiki'
 
 import type { FC, MouseEvent } from 'react'
 
-import type { Menu, MenuVisibleItem, Tag, User } from '@/types'
+import type { Material, Menu, MenuVisibleItem, Tag, User } from '@/types'
 
 type Props = { user: User | null }
 
 
-export const menuOutline = ({ tag, wikiId, user, pathName }: { 
+export const menuOutline = (
-    tag?: Tag | null
+    { tag, material, wikiId, user, pathName }: {
-    wikiId: number | null
+	tag?: Tag | null
-    user: User | null,
+	material?: Material | null
-    pathName: string }): Menu => {
+	wikiId: number | null
-  const postCount = tag?.postCount ?? 0
+	user: User | null,
+	pathName: string },
+): Menu => {
+  const postCount = tag?.postCount ?? material?.tag?.postCount ?? 0
 
   const wikiPageFlg = Boolean (/^\/wiki\/(?!new|changes)[^/]+/.test (pathName) && wikiId)
   const wikiTitle = pathName.split ('/')[2] ?? ''
 
   const tagFlg = /^\/tags\/\d+/.test (pathName)
 
+  const materialFlg = /^\/materials\/\d+/.test (pathName)
+
   return [
       { name: '広場', to: '/posts', subMenu: [
 	  { name: '一覧', to: '/posts' },
@@ -49,12 +55,18 @@ export const menuOutline = ({ tag, wikiId, user, pathName }: {
 	    visible: tagFlg },
 	  { name: '履歴', to: `/tags/changes?id=${ tag?.id }`,
 	    visible: tagFlg && tag?.category !== 'nico' }] },
-      { name: '素材', to: '/materials', visible: false, subMenu: [
+      { name: '素材', to: '/materials', visible: true, subMenu: [
 	  { name: '一覧', to: '/materials' },
-	  { name: '検索', to: '/materials/search', visible: false }, 
 	  { name: '追加', to: '/materials/new' },
-	  { name: '全体履歴', to: '/materials/changes', visible: false },
+	  { name: '抑止', to: '/materials/suppressions' },
-	  { name: 'ヘルプ', to: '/wiki/ヘルプ:素材集' }] },
+	  { name: '全体履歴', to: '/materials/changes' },
+	  { name: 'ヘルプ', to: '/wiki/ヘルプ:素材管理' },
+	  { component: <Separator/>, visible: materialFlg },
+	  { name: `広場 (${ postCount || 0 })`,
+	    to: `/posts?tags=${ encodeURIComponent (material?.tag?.name ?? '') }`,
+	    visible: materialFlg && Boolean (material?.tag) },
+	  { name: '履歴', to: `/materials/changes?material_id=${ material?.id }`,
+	    visible: materialFlg }] },
       { name: 'Wiki', to: '/wiki/ヘルプ:ホーム', base: '/wiki', subMenu: [
 	  { name: '検索', to: '/wiki' },
 	  { name: '新規', to: '/wiki/new' },
@@ -119,15 +131,23 @@ const TopNav: FC<Props> = ({ user }) => {
       queryFn: () => fetchWikiPage (wikiIdStr, { }) })
 
   const tagFlg = /^\/tags\/\d+/.test (location.pathname)
-  const effectiveTitle = (tagFlg ? location.pathname.split ('/')[2] : wikiPage?.title) ?? ''
+  const materialFlg = /^\/materials\/\d+/.test (location.pathname)
+  const effectiveTitle = (((tagFlg || materialFlg)
+			   ? location.pathname.split ('/')[2]
+			   : wikiPage?.title)
+			  ?? '')
 
   const { data: tag } = useQuery ({
       enabled: Boolean (effectiveTitle),
       queryKey: tagsKeys.show (effectiveTitle),
       queryFn: () => (tagFlg ? fetchTag : fetchTagByName) (effectiveTitle) })
 
+  const { data: material } = useQuery ({
+      enabled: Boolean (effectiveTitle),
+      queryKey: materialsKeys.show (effectiveTitle),
+      queryFn: () => fetchMaterial (effectiveTitle) })
 
-  const menu = menuOutline ({ tag, wikiId, user, pathName: location.pathname })
+  const menu = menuOutline ({ tag, material, wikiId, user, pathName: location.pathname })
   const visibleMenu = menu.filter ((item): item is MenuVisibleItem => item.visible ?? true)
   const moreMenu = menu.filter (item =>
       !(item.visible ?? true)

frontend/src/components/common/PageTitle.tsx

@@ -1,12 +1,14 @@
 import React from 'react'
 
+import { cn } from '@/lib/utils'
+
 import type { FC } from 'react'
 
-type Props = { children: React.ReactNode }
+type Props = { children: React.ReactNode; className?: string }
 
 
-const PageTitle: FC<Props> = ({ children }) => (
+const PageTitle: FC<Props> = ({ children, className, ...rest }) => (
-    <h1 className="text-2xl font-bold mb-2">
+    <h1 className={cn ('text-2xl font-bold mb-2', className)} {...rest}>
       {children}
     </h1>)
 

frontend/src/components/ui/input.tsx

@@ -1,19 +1,19 @@
-import * as React from "react"
+import * as React from 'react'
-
+
-import { cn } from "@/lib/utils"
+import { cn } from '@/lib/utils'
-
+
-const Input = React.forwardRef<HTMLInputElement, React.ComponentProps<"input">>(
+const Input = React.forwardRef<HTMLInputElement, React.ComponentProps<'input'>>(
-  ({ className, type, ...props }, ref) => {
+  ({ className, type, ...props }, ref) => {
-    return (
+    return (
-      <input
+      <input
-	type={type}
+	type={type}
-	className={cn(
+	className={cn(
-	  "flex h-10 w-full rounded-md border border-input bg-background px-3 py-2 text-base ring-offset-background file:border-0 file:bg-transparent file:text-sm file:font-medium file:text-foreground placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 disabled:cursor-not-allowed disabled:opacity-50 md:text-sm",
+	  'flex h-10 w-full rounded-md border border-input bg-background px-3 py-2 text-base ring-offset-background file:border-0 file:bg-transparent file:text-sm file:font-medium file:text-foreground placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 disabled:cursor-not-allowed disabled:opacity-50 md:text-sm',
-	  className
+	  className)}
-)}
+	ref={ref}
-	ref={ref}
+	{...props}
-	{...props}
+      />)
-      />
+  })
-)
+Input.displayName = 'Input'
-  }
+
-)
+export { Input }

frontend/src/components/ui/switch.tsx

@@ -1,26 +1,26 @@
-"use client"
+'use client'
-
+
-import * as React from "react"
+import * as React from 'react'
-import * as SwitchPrimitives from "@radix-ui/react-switch"
+import * as SwitchPrimitives from '@radix-ui/react-switch'
-
+
-import { cn } from "@/lib/utils"
+import { cn } from '@/lib/utils'
-
+
-const Switch = React.forwardRef<
+const Switch = React.forwardRef<
-  React.ElementRef<typeof SwitchPrimitives.Root>,
+  React.ElementRef<typeof SwitchPrimitives.Root>,
-  React.ComponentPropsWithoutRef<typeof SwitchPrimitives.Root>
+  React.ComponentPropsWithoutRef<typeof SwitchPrimitives.Root>
->(({ className, ...props }, ref) => (
+>(({ className, ...props }, ref) => (
-  <SwitchPrimitives.Root
+  <SwitchPrimitives.Root
-    className={cn(
+    className={cn(
-      "peer inline-flex h-6 w-11 shrink-0 cursor-pointer items-center rounded-full border-2 border-transparent transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 focus-visible:ring-offset-background disabled:cursor-not-allowed disabled:opacity-50 data-[state=checked]:bg-primary data-[state=unchecked]:bg-input",
+      'peer inline-flex h-6 w-11 shrink-0 cursor-pointer items-center rounded-full border-2 border-transparent transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 focus-visible:ring-offset-background disabled:cursor-not-allowed disabled:opacity-50 data-[state=checked]:bg-primary data-[state=unchecked]:bg-input',
-      className
+      className)}
-)}
+    {...props}
-    {...props}
+    ref={ref}
-    ref={ref}
+  >
-  >
+    <SwitchPrimitives.Thumb
-    <SwitchPrimitives.Thumb
+      className={cn(
-      className={cn(
+	'pointer-events-none block h-5 w-5 rounded-full bg-background shadow-lg ring-0 transition-transform data-[state=checked]:translate-x-5 data-[state=unchecked]:translate-x-0')}
-	"pointer-events-none block h-5 w-5 rounded-full bg-background shadow-lg ring-0 transition-transform data-[state=checked]:translate-x-5 data-[state=unchecked]:translate-x-0"
+    />
-)}
+  </SwitchPrimitives.Root>))
-    />
+Switch.displayName = SwitchPrimitives.Root.displayName
-  </SwitchPrimitives.Root>
+
-))
+export { Switch }

frontend/src/lib/materials.ts

@@ -1,45 +1,31 @@
-import {
+import { apiGet, isApiError, apiPost, apiPut } from '@/lib/api'
-    apiGet,
-    isApiError,
-    apiPost,
-    apiPut,
-} from '@/lib/api'
 
-import type {
+import type { Material,
-    Material,
+	      MaterialIndexResponse,
-    MaterialVersion,
+	      MaterialVersion,
-    FetchMaterialsParams,
+	      FetchMaterialsParams,
-    MaterialFilter,
+	      MaterialFilter,
-    MaterialSyncSuppression,
+	      MaterialSyncSuppression,
-    MaterialSidebarTag,
+	      MaterialSidebarTag,
-    MaterialTagTree,
+	      MaterialTagTree } from '@/types'
-} from '@/types'
 
 export type FetchMaterialTreeParams = {
     parentId?:       number | null
-    materialFilter:  MaterialFilter
+    materialFilter:  MaterialFilter }
-}
 
-export type MaterialIndexResponse = {
+export type MaterialSyncSuppressionResponse = { suppressions: MaterialSyncSuppression[] }
-    materials: Material[]
-    count:     number
-}
-
-export type MaterialSyncSuppressionResponse = {
-    suppressions: MaterialSyncSuppression[]
-}
 
 export type MaterialChangesResponse = {
     versions: MaterialVersion[]
-    count:    number
+    count:    number }
-}
 
 const MATERIAL_FILTERS: MaterialFilter[] = ['present', 'missing', 'any']
 
 
 export const parseMaterialFilter = (
     value: unknown,
-    fallback: MaterialFilter = 'present'): MaterialFilter =>
+    fallback: MaterialFilter = 'present',
+): MaterialFilter =>
     typeof value === 'string' && MATERIAL_FILTERS.includes (value as MaterialFilter)
     ? value as MaterialFilter
     : fallback
@@ -48,11 +34,16 @@ export const parseMaterialFilter = (
 export const fetchMaterials = async (
     { q, tagState, mediaKind, createdFrom, createdTo,
       updatedFrom, updatedTo, sort, direction, page,
-      limit }: FetchMaterialsParams): Promise<MaterialIndexResponse> =>
+      tagId, includeDescendants, groupBy,
+      limit }: FetchMaterialsParams,
+): Promise<MaterialIndexResponse> =>
     await apiGet ('/materials', { params: {
 	...(q && { q }),
 	tag_state:   tagState,
 	media_kind:  mediaKind,
+	...(tagId != null && { tag_id: tagId }),
+	...(includeDescendants && { include_descendants: '1' }),
+	...(groupBy !== 'none' && { group_by: groupBy }),
 	...(createdFrom && { created_from: createdFrom }),
 	...(createdTo && { created_to: createdTo }),
 	...(updatedFrom && { updated_from: updatedFrom }),

frontend/src/pages/materials/MaterialDetailPage.test.tsx

@@ -7,9 +7,9 @@ import { buildMaterial, buildTag } from '@/test/factories'
 import { renderWithProviders } from '@/test/render'
 
 const api = vi.hoisted (() => ({
-  apiGet: vi.fn (),
+  apiGet:     vi.fn (),
-  apiPatch: vi.fn (),
+  apiPut:     vi.fn (),
-  apiPut: vi.fn (),
+  isApiError: vi.fn (),
 }))
 
 const wikiApi = vi.hoisted (() => ({
@@ -35,7 +35,11 @@ const renderPage = () =>
 describe ('MaterialDetailPage', () => {
   beforeEach (() => {
     vi.clearAllMocks ()
-    api.apiGet.mockResolvedValue ([])
+    api.apiGet.mockImplementation (async (path: string) =>
+      path === '/tags/autocomplete'
+      ? []
+      : buildMaterial ({ id: 8 }))
+    api.isApiError.mockReturnValue (false)
     wikiApi.fetchWikiPages.mockResolvedValue ([])
     vi.stubGlobal ('fetch', vi.fn (async () => ({
       blob: async () => new Blob (['image'], { type: 'image/png' }),
@@ -86,4 +90,22 @@ describe ('MaterialDetailPage', () => {
     expect (formData.get ('export_paths[legacy_drive]')).toBe ('素材/new.png')
     expect (toastApi.toast).toHaveBeenCalledWith ({ title: '更新成功!' })
   })
+
+  it ('shows not found when material API returns 404', async () => {
+    api.isApiError.mockReturnValue (true)
+    api.apiGet.mockRejectedValueOnce ({ response: { status: 404 } })
+
+    renderPage ()
+
+    expect (await screen.findByText ('素材が見つかりませんでした．')).toBeInTheDocument ()
+  })
+
+  it ('shows an error for non-404 material API failures', async () => {
+    api.isApiError.mockReturnValue (false)
+    api.apiGet.mockRejectedValueOnce (new Error ('network error'))
+
+    renderPage ()
+
+    expect (await screen.findByText ('素材の取得に失敗しました．')).toBeInTheDocument ()
+  })
 })

frontend/src/pages/materials/MaterialDetailPage.tsx

@@ -8,7 +8,6 @@ import WikiBody from '@/components/WikiBody'
 import FieldError from '@/components/common/FieldError'
 import FormField from '@/components/common/FormField'
 import PageTitle from '@/components/common/PageTitle'
-import PrefetchLink from '@/components/PrefetchLink'
 import TabGroup, { Tab } from '@/components/common/TabGroup'
 import TagInput from '@/components/common/TagInput'
 import MainArea from '@/components/layout/MainArea'
@@ -119,12 +118,6 @@ const MaterialDetailPage: FC = () => {
 		 : materialTitle}
 	      </PageTitle>
 
-	      <PrefetchLink
-		  to={`/materials/changes?material_id=${ material.id }`}
-		  className="text-sm text-sky-700 underline underline-offset-2 dark:text-sky-300">
-		この素材の履歴
-	      </PrefetchLink>
-
 	      {(material.file && material.contentType) && (
 		  (/image\/.*/.test (material.contentType) && (
 		      <img src={material.file} alt={material.tag?.name || undefined}/>))
@@ -134,17 +127,12 @@ const MaterialDetailPage: FC = () => {
 		      <audio src={material.file} controls/>)))}
 
 	      <TabGroup>
-		<Tab name="Wiki">
+		{material.tag && (
-		  {material.tag
+		    <Tab name="Wiki">
-		   ? (
 		      <WikiBody
 			  title={material.tag.name}
-			  body={material.wikiPageBody ?? undefined}/>)
+			  body={material.wikiPageBody ?? undefined}/>
-		   : (
+		    </Tab>)}
-		      <p className="text-stone-700 dark:text-stone-300">
-			タグ未設定の素材です．
-		      </p>)}
-		</Tab>
 
 		<Tab name="編輯">
 		  <div className="max-w-wl space-y-4 pt-2">

frontend/src/pages/materials/MaterialHistoryPage.tsx

@@ -80,14 +80,7 @@ const MaterialHistoryPage: FC = () => {
 	</Helmet>
 
 	<div className="space-y-5">
-	  <div className="flex flex-wrap items-center justify-between gap-3">
+	  <PageTitle>素材履歴</PageTitle>
-	    <PageTitle>素材履歴</PageTitle>
-	    <PrefetchLink
-		to="/materials"
-		className="text-sm text-sky-700 underline underline-offset-2 dark:text-sky-300">
-	      素材一覧へ戻る
-	    </PrefetchLink>
-	  </div>
 
 	  <form
 	      onSubmit={handleSearch}
@@ -112,20 +105,6 @@ const MaterialHistoryPage: FC = () => {
 			onChange={e => setTagInput (e.target.value)}
 			className={inputClass (invalid)}/>)}
 	      </FormField>
-
-	      <FormField label="イベント">
-		{({ invalid }) => (
-		    <select
-			value={eventTypeInput}
-			onChange={e => setEventTypeInput (e.target.value)}
-			className={inputClass (invalid)}>
-		      <option value="">すべて</option>
-		      <option value="create">create</option>
-		      <option value="update">update</option>
-		      <option value="discard">discard</option>
-		      <option value="restore">restore</option>
-		    </select>)}
-	      </FormField>
 	    </div>
 
 	    <button
@@ -150,7 +129,6 @@ const MaterialHistoryPage: FC = () => {
 		  <table className="w-full min-w-[1200px] table-fixed border-collapse">
 		    <colgroup>
 		      <col className="w-48"/>
-		      <col className="w-32"/>
 		      <col className="w-28"/>
 		      <col className="w-24"/>
 		      <col className="w-64"/>
@@ -163,7 +141,6 @@ const MaterialHistoryPage: FC = () => {
 		    <thead className="border-b-2 border-black dark:border-white">
 		      <tr>
 			<th className="p-2 text-left">日時</th>
-			<th className="p-2 text-left">event_type</th>
 			<th className="p-2 text-left">素材 ID</th>
 			<th className="p-2 text-left">版</th>
 			<th className="p-2 text-left">タグ名</th>
@@ -180,7 +157,6 @@ const MaterialHistoryPage: FC = () => {
 			      key={version.id}
 			      className="even:bg-gray-100 dark:even:bg-gray-700">
 			    <td className="p-2">{dateString (version.createdAt)}</td>
-			    <td className="p-2">{version.eventType}</td>
 			    <td className="p-2">
 			      <PrefetchLink to={`/materials/${ version.materialId }`}>
 				#{version.materialId}

frontend/src/pages/materials/MaterialListPage.test.tsx

@@ -1,5 +1,5 @@
-import { screen, waitFor } from '@testing-library/react'
+import { fireEvent, screen, waitFor } from '@testing-library/react'
-import { describe, expect, it, vi } from 'vitest'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import MaterialListPage from '@/pages/materials/MaterialListPage'
 import { buildMaterial, buildTag } from '@/test/factories'
@@ -12,51 +12,169 @@ const api = vi.hoisted (() => ({
 vi.mock ('@/lib/api', () => api)
 
 describe ('MaterialListPage', () => {
-  it ('shows the empty selection guide without a tag query', () => {
+  beforeEach (() => {
-    renderWithProviders (<MaterialListPage/>, { route: '/materials' })
+    vi.clearAllMocks ()
-
+    api.apiGet.mockResolvedValue ({ materials: [], count: 0 })
-    expect (screen.getByText ('左のリストから照会したいタグを選択してください。')).toBeInTheDocument ()
-    expect (screen.getByRole ('link', { name: '素材を新規追加する' })).toHaveAttribute (
-        'href',
-        '/materials/new',
-    )
   })
 
-  it ('loads materials for a tag query', async () => {
+  it ('loads the material index on the initial page', async () => {
-    const tag = {
+    renderWithProviders (<MaterialListPage/>, { route: '/materials' })
-      ...buildTag ({
-        id:       4,
-        name:     '素材タグ',
-        category: 'material',
-      }),
-      material: buildMaterial ({ id: 8, contentType: 'image/png', file: 'image.png' }),
-      children: [],
-    }
-    api.apiGet.mockResolvedValueOnce (tag)
-
-    renderWithProviders (<MaterialListPage/>, { route: '/materials?tag=%E7%B4%A0%E6%9D%90' })
 
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenCalledWith (
-          '/tags/name/%E7%B4%A0%E6%9D%90/materials',
+          '/materials',
+          { params: {
+              tag_state:  'all',
+              media_kind: 'all',
+              sort:       'created_at',
+              direction:  'desc',
+              page:       1,
+              limit:      20,
+          } },
       )
     })
-    expect (await screen.findByRole ('link', { name: '素材タグ' })).toBeInTheDocument ()
+    expect (await screen.findByText ('素材はありません。')).toBeInTheDocument ()
-    expect (screen.getByRole ('link', { name: '' })).toHaveAttribute ('href', '/materials/8')
   })
 
-  it ('offers adding a missing non-meme material', async () => {
+  it ('shows materials in the default card view', async () => {
     api.apiGet.mockResolvedValueOnce ({
-      ...buildTag ({ name: '未登録', category: 'material' }),
+      materials: [
-      material: null,
+        buildMaterial ({
-      children: [],
+          id:          8,
+          tag:         buildTag ({ name: '素材タグ', category: 'material' }),
+          thumbnail:   'thumb.png',
+          mediaKind:   'image',
+          contentType: 'image/png',
+        }),
+      ],
+      count: 1,
     })
 
-    renderWithProviders (<MaterialListPage/>, { route: '/materials?tag=x' })
+    renderWithProviders (<MaterialListPage/>, { route: '/materials' })
 
-    expect (await screen.findByRole ('link', { name: '追加' })).toHaveAttribute (
+    expect ((await screen.findByText ('素材タグ')).closest ('a'))
+      .toHaveAttribute ('href', '/materials/8')
+    expect (screen.getByText (/画像 \/ 令和8年1月2日/)).toBeInTheDocument ()
+  })
+
+  it ('submits list filters as material index params', async () => {
+    renderWithProviders (<MaterialListPage/>, { route: '/materials' })
+
+    fireEvent.change (screen.getByPlaceholderText ('タグ名 / URL / ファイル名'), {
+      target: { value: '虹夏' },
+    })
+    const selects = screen.getAllByRole ('combobox')
+    fireEvent.change (selects[0], {
+      target: { value: 'untagged' },
+    })
+    fireEvent.change (selects[1], {
+      target: { value: 'image' },
+    })
+    fireEvent.click (screen.getByRole ('button', { name: '検索' }))
+
+    await waitFor (() => {
+      expect (api.apiGet).toHaveBeenCalledWith (
+          '/materials',
+          expect.objectContaining ({ params: expect.objectContaining ({
+            q:          '虹夏',
+            tag_state:  'untagged',
+            media_kind: 'image',
+          }) }),
+      )
+    })
+  })
+
+  it ('keeps a route back to the material search top for untagged materials', async () => {
+    renderWithProviders (
+        <MaterialListPage/>,
+        { route: '/materials?tag_state=untagged&material_filter=any' },
+    )
+
+    expect (await screen.findByRole (
+        'link',
+        { name: '素材検索トップへ戻る' },
+    )).toHaveAttribute ('href', '/materials?material_filter=any')
+  })
+
+  it ('uses list view for detailed material rows', async () => {
+    api.apiGet.mockResolvedValueOnce ({
+      materials: [
+        buildMaterial ({
+          id:           9,
+          tag:          buildTag ({ name: '詳細素材', category: 'material' }),
+          mediaKind:    'file_other',
+          fileByteSize: 2048,
+        }),
+      ],
+      count: 1,
+    })
+
+    renderWithProviders (<MaterialListPage/>, { route: '/materials?view=list' })
+
+    expect (await screen.findByRole ('link', { name: '詳細素材' })).toHaveAttribute (
         'href',
-        '/materials/new?tag=%E6%9C%AA%E7%99%BB%E9%8C%B2',
+        '/materials/9',
+    )
+    expect (screen.getByText ('サイズ:')).toBeInTheDocument ()
+    expect (screen.getByText ('2.0 KB')).toBeInTheDocument ()
+  })
+
+  it ('shows the selected tag scope and tag-specific add links', async () => {
+    api.apiGet.mockResolvedValueOnce ({
+      materials: [
+        buildMaterial ({
+          id:  10,
+          tag: buildTag ({ id: 30, name: '泣き', category: 'material' }),
+        }),
+      ],
+      count:    1,
+      tagScope: {
+        tag:                { id: 20, name: '伊地知ニジカ', category: 'material' },
+        includeDescendants: true,
+      },
+      groups: [
+        {
+          key:         'tag:30',
+          tag:         { id: 30, name: '泣き', category: 'material' },
+          materialIds: [10],
+          count:       1,
+        },
+      ],
+    })
+
+    renderWithProviders (
+        <MaterialListPage/>,
+        { route: '/materials?tag_id=20&include_descendants=1&group_by=parent_tag' },
+    )
+
+    expect (await screen.findByText (
+        (_, element) => element?.textContent === '伊地知ニジカ 配下の素材を表示中',
+    )).toBeInTheDocument ()
+
+    expect (screen.getByRole ('link', { name: '泣き' })).toHaveAttribute (
+        'href',
+        '/materials?tag_id=30&include_descendants=1&group_by=parent_tag&material_filter=present',
+    )
+    expect (screen.getByRole ('link', { name: 'タグ選択を解除' })).toHaveAttribute (
+        'href',
+        '/materials?material_filter=present',
+    )
+  })
+
+  it ('shows a clear link when tag_id does not resolve to tag_scope', async () => {
+    api.apiGet.mockResolvedValueOnce ({
+      materials: [],
+      count:     0,
+      tagScope:  null,
+      groups:    [],
+    })
+
+    renderWithProviders (<MaterialListPage/>, { route: '/materials?tag_id=999' })
+
+    expect (await screen.findByText ('選択中タグが見つかりません．')).toBeInTheDocument ()
+    expect (screen.getByRole ('link', { name: 'タグ選択を解除' })).toHaveAttribute (
+        'href',
+        '/materials?material_filter=present',
     )
   })
 })

frontend/src/pages/materials/MaterialListPage.tsx

@@ -10,21 +10,23 @@ import FormField from '@/components/common/FormField'
 import PageTitle from '@/components/common/PageTitle'
 import Pagination from '@/components/common/Pagination'
 import MainArea from '@/components/layout/MainArea'
-import { API_BASE_URL, SITE_TITLE } from '@/config'
+import { SITE_TITLE } from '@/config'
 import { fetchMaterials, parseMaterialFilter } from '@/lib/materials'
 import { materialsKeys } from '@/lib/queryKeys'
 import { dateString, inputClass } from '@/lib/utils'
 
 import type { FC, FormEvent } from 'react'
 
-import type {
+import type { FetchMaterialsParams,
-    FetchMaterialsParams,
+	      Material,
-    Material,
+	      MaterialFilter,
-    MaterialIndexDirection,
+	      MaterialIndexGroup,
-    MaterialIndexMediaKind,
+	      MaterialIndexGroupBy,
-    MaterialIndexSort,
+	      MaterialIndexDirection,
-    MaterialIndexTagState,
+	      MaterialIndexMediaKind,
-    MaterialIndexView } from '@/types'
+	      MaterialIndexSort,
+	      MaterialIndexTagState,
+	      MaterialIndexView } from '@/types'
 
 const MEDIA_KIND_LABELS: Record<Material['mediaKind'], string> = {
     image:      '画像',
@@ -39,16 +41,16 @@ const MEDIA_FILTER_LABELS: Record<MaterialIndexMediaKind, string> = {
     video:      '動画',
     audio:      '音声',
     file_other: 'その他ファイル',
-    url_only:   'URL のみ'}
+    url_only:   '外部リンクのみ'}
 
 const SORT_LABELS: Record<MaterialIndexSort, string> = {
     created_at:     '作成日時',
     updated_at:     '更新日時',
     tag_name:       'タグ名',
     media_kind:     '種類',
-    file_byte_size: 'ファイルサイズ',
+    file_byte_size: '容量',
-    version_no:     'バージョン',
+    version_no:     '版',
-    id:             'ID'}
+    id:             'Id.'}
 
 
 const setIf = (qs: URLSearchParams, key: string, value: string | null) => {
@@ -79,6 +81,36 @@ const materialTitle = (material: Material): string =>
     material.tag?.name ?? `素材 #${ material.id }`
 
 
+const groupedTagPath = (
+    tagId: number,
+    materialFilter: MaterialFilter,
+): string =>
+    `/materials?tag_id=${ tagId }&include_descendants=1&group_by=parent_tag`
+    + `&material_filter=${ materialFilter }`
+
+
+const materialNewPath = (
+    tagName: string,
+    returnTo: string,
+): string =>
+    `/materials/new?tag=${ encodeURIComponent (tagName) }`
+    + `&return_to=${ encodeURIComponent (returnTo) }`
+
+
+const clearedTagSelectionPath = (
+    locationSearch: string,
+    materialFilter: MaterialFilter,
+): string => {
+    const qs = new URLSearchParams (locationSearch)
+    qs.delete ('tag_id')
+    qs.delete ('include_descendants')
+    qs.delete ('group_by')
+    qs.delete ('page')
+    qs.set ('material_filter', materialFilter)
+    return `/materials?${ qs.toString () }`
+}
+
+
 const MaterialThumb: FC<{ material: Material }> = ({ material }) => (
     <div
 	className={`flex aspect-square h-[180px] w-[180px] items-center justify-center
@@ -86,7 +118,7 @@ const MaterialThumb: FC<{ material: Material }> = ({ material }) => (
 		    text-stone-900 shadow-sm dark:border-stone-700 dark:bg-stone-900
 		    dark:text-stone-100`}>
       {material.thumbnail
-       ? <img src={material.thumbnail} alt="" className="h-full w-full object-contain"/>
+       ? <img src={material.thumbnail} alt="" className="block h-full w-full object-cover"/>
        : (
 	  <span
 	      className="px-2 text-2xl leading-tight"
@@ -154,6 +186,28 @@ const MaterialListItem: FC<{ material: Material }> = ({ material }) => (
     </article>)
 
 
+const GroupHeading: FC<{
+    count:          number
+    materialFilter: MaterialFilter
+    title:          string
+    tagId:          number
+}> = ({ count, materialFilter, title, tagId }) => (
+    <div className="flex items-center gap-2 border-b border-stone-200 pb-2
+		    dark:border-stone-700">
+      <PrefetchLink
+	  to={groupedTagPath (tagId, materialFilter)}
+	  className="font-medium text-sky-700 underline underline-offset-2
+		     dark:text-sky-300 w-full">
+	{title}
+      </PrefetchLink>
+      <div className="text-right w-auto">
+	<span className="text-nowrap text-sm text-stone-600 dark:text-stone-300">
+	  {count} 件
+	</span>
+      </div>
+    </div>)
+
+
 const MaterialListPage: FC = () => {
   const location = useLocation ()
   const navigate = useNavigate ()
@@ -162,7 +216,10 @@ const MaterialListPage: FC = () => {
 
   const page = Number (query.get ('page') ?? 1)
   const limit = Number (query.get ('limit') ?? 20)
-  const qQuery = query.get ('q') ?? query.get ('tag') ?? ''
+  const qQuery = query.get ('q') ?? ''
+  const tagIdQuery = Number (query.get ('tag_id') ?? 0)
+  const tagId = tagIdQuery > 0 ? tagIdQuery : null
+  const includeDescendants = query.get ('include_descendants') === '1'
   const tagState = query.get ('unclassified') === '1'
       ? 'untagged'
       : parseOption<MaterialIndexTagState> (
@@ -182,6 +239,11 @@ const MaterialListPage: FC = () => {
       query.get ('direction'),
       ['asc', 'desc'],
       'desc')
+  const groupByQuery = parseOption<MaterialIndexGroupBy> (
+      query.get ('group_by'),
+      ['none', 'parent_tag'],
+      'none')
+  const groupBy = tagId == null ? 'none' : groupByQuery
   const view = parseOption<MaterialIndexView> (query.get ('view'), ['card', 'list'], 'card')
   const createdFromQuery = query.get ('created_from') ?? ''
   const createdToQuery = query.get ('created_to') ?? ''
@@ -191,6 +253,7 @@ const MaterialListPage: FC = () => {
   const [q, setQ] = useState ('')
   const [tagStateInput, setTagStateInput] = useState<MaterialIndexTagState> ('all')
   const [mediaKindInput, setMediaKindInput] = useState<MaterialIndexMediaKind> ('all')
+  const [groupByInput, setGroupByInput] = useState<MaterialIndexGroupBy> ('none')
   const [createdFrom, setCreatedFrom] = useState<string | null> (null)
   const [createdTo, setCreatedTo] = useState<string | null> (null)
   const [updatedFrom, setUpdatedFrom] = useState<string | null> (null)
@@ -200,6 +263,9 @@ const MaterialListPage: FC = () => {
       q: qQuery,
       tagState,
       mediaKind,
+      tagId,
+      includeDescendants,
+      groupBy,
       createdFrom: createdFromQuery,
       createdTo: createdToQuery,
       updatedFrom: updatedFromQuery,
@@ -212,18 +278,33 @@ const MaterialListPage: FC = () => {
   const { data, isLoading, isError } = useQuery ({
       queryKey: materialsKeys.index (keys),
       queryFn:  () => fetchMaterials (keys)})
+  const tagScope = data?.tagScope ?? null
   const materials = data?.materials ?? []
+  const groups = data?.groups ?? []
   const totalPages = data ? Math.ceil (data.count / limit) : 0
+  const materialsById = useMemo (
+      () => new Map (materials.map (material => [material.id, material])),
+      [materials],
+  )
+  const groupedMaterialIds = useMemo (
+      () => new Set (groups.flatMap (group => group.materialIds)),
+      [groups],
+  )
+  const ungroupedMaterials = useMemo (
+      () => materials.filter (material => !groupedMaterialIds.has (material.id)),
+      [groupedMaterialIds, materials],
+  )
 
   useEffect (() => {
     setQ (qQuery)
     setTagStateInput (tagState)
     setMediaKindInput (mediaKind)
+    setGroupByInput (groupBy)
     setCreatedFrom (createdFromQuery)
     setCreatedTo (createdToQuery)
     setUpdatedFrom (updatedFromQuery)
     setUpdatedTo (updatedToQuery)
-  }, [createdFromQuery, createdToQuery, mediaKind, qQuery, tagState,
+  }, [createdFromQuery, createdToQuery, groupBy, mediaKind, qQuery, tagState,
       updatedFromQuery, updatedToQuery])
 
   const search = (e: FormEvent) => {
@@ -239,19 +320,77 @@ const MaterialListPage: FC = () => {
     setIf (qs, 'updated_to', updatedTo)
     qs.set ('sort', sort)
     qs.set ('direction', direction)
+    qs.set ('group_by', tagId == null ? 'none' : groupByInput)
     qs.set ('view', view)
     qs.set ('page', '1')
     qs.set ('limit', String (limit))
     qs.set ('material_filter', materialFilter)
+    if (tagId != null)
+      qs.set ('tag_id', String (tagId))
+
+    if (includeDescendants)
+      qs.set ('include_descendants', '1')
+
     navigate (`/materials?${ qs.toString () }`)
   }
 
   const updateQuery = (changes: Record<string, string>) => {
     const qs = new URLSearchParams (location.search)
-    Object.entries (changes).forEach (([key, value]) => qs.set (key, value))
+    Object.entries (changes).forEach (([key, value]) => {
+      if (value === '')
+	qs.delete (key)
+      else
+	qs.set (key, value)
+    })
     navigate (`/materials?${ qs.toString () }`)
   }
 
+  const renderMaterialCollection = (rows: Material[]) =>
+      view === 'card'
+      ? (
+	  <div className="grid grid-cols-[repeat(auto-fill,minmax(196px,1fr))]
+			  justify-items-center gap-4">
+	    {rows.map (material => (
+		<MaterialCard key={material.id} material={material}/>))}
+	  </div>)
+      : (
+	  <div className="space-y-3">
+	    {rows.map (material => (
+		<MaterialListItem key={material.id} material={material}/>))}
+	  </div>)
+
+  const renderGroupedMaterials = (materialGroups: MaterialIndexGroup[]) => (
+      <div className="space-y-6">
+	{materialGroups.map (group => {
+	  const groupMaterials =
+	      group.materialIds
+	      .map (materialId => materialsById.get (materialId))
+	      .filter ((material): material is Material => material != null)
+
+	  if (groupMaterials.length === 0)
+	    return null
+
+	  return (
+	      <section key={group.key} className="space-y-3">
+		<GroupHeading
+		    tagId={group.tag.id}
+		    title={group.tag.name}
+		    count={group.count}
+		    materialFilter={materialFilter}/>
+		{renderMaterialCollection (groupMaterials)}
+	      </section>)
+	})}
+	{ungroupedMaterials.length > 0 && (
+	    <section className="space-y-3">
+	      <div className="border-b border-stone-200 pb-2 dark:border-stone-700">
+		<span className="font-medium text-stone-900 dark:text-stone-100">
+		  その他
+		</span>
+	      </div>
+	      {renderMaterialCollection (ungroupedMaterials)}
+	    </section>)}
+      </div>)
+
   return (
       <MainArea>
 	<Helmet>
@@ -263,35 +402,15 @@ const MaterialListPage: FC = () => {
 		  src: url(${ nikumaru }) format('opentype');
 		}`}
 	  </style>
-	  <title>{`素材一覧 | ${ SITE_TITLE }`}</title>
+	  <title>{`素材管理 | ${ SITE_TITLE }`}</title>
 	</Helmet>
 
 	<div className="space-y-5">
 	  <div className="flex flex-wrap items-center justify-between gap-3">
-	    <PageTitle>素材一覧</PageTitle>
+	    <PageTitle className="my-auto">素材管理</PageTitle>
 	    <div className="flex flex-wrap gap-2">
-	      <PrefetchLink
+	      {/* TODO: 局所出力を可能にする */}
-		  to="/materials/new"
+	      {/* <a
-		  className="rounded-full border border-stone-300 bg-white px-4 py-2 text-sm
-			     text-stone-900 hover:bg-stone-100 dark:border-stone-700
-			     dark:bg-stone-900 dark:text-stone-100 dark:hover:bg-stone-800">
-		新規素材を追加
-	      </PrefetchLink>
-	      <PrefetchLink
-		  to="/materials/suppressions"
-		  className="rounded-full border border-stone-300 bg-white px-4 py-2 text-sm
-			     text-stone-900 hover:bg-stone-100 dark:border-stone-700
-			     dark:bg-stone-900 dark:text-stone-100 dark:hover:bg-stone-800">
-		同期元抑止
-	      </PrefetchLink>
-	      <PrefetchLink
-		  to="/materials/changes"
-		  className="rounded-full border border-stone-300 bg-white px-4 py-2 text-sm
-			     text-stone-900 hover:bg-stone-100 dark:border-stone-700
-			     dark:bg-stone-900 dark:text-stone-100 dark:hover:bg-stone-800">
-		履歴
-	      </PrefetchLink>
-	      <a
 		  href={`${ API_BASE_URL }/materials/download.zip?profile=legacy_drive`}
 		  target="_blank"
 		  rel="noopener noreferrer"
@@ -299,10 +418,38 @@ const MaterialListPage: FC = () => {
 			     text-stone-900 hover:bg-stone-100 dark:border-stone-700
 			     dark:bg-stone-900 dark:text-stone-100 dark:hover:bg-stone-800">
 		ZIP をダウンロード
-	      </a>
+	      </a> */}
 	    </div>
 	  </div>
 
+	  {tagScope && (
+	      <div className="flex flex-wrap items-center gap-3 rounded-lg border
+			      border-sky-200 bg-sky-50 px-4 py-3 text-sm text-sky-900
+			      dark:border-sky-800 dark:bg-sky-950 dark:text-sky-100">
+		<span>
+		  {tagScope.tag.name}
+		  {tagScope.includeDescendants ? ' 配下の素材を表示中' : ' の素材を表示中'}
+		</span>
+		<PrefetchLink
+		    to={clearedTagSelectionPath (location.search, materialFilter)}
+		    className="font-medium underline underline-offset-2
+			       text-sky-700 dark:text-sky-300">
+		  タグ選択を解除
+		</PrefetchLink>
+	      </div>)}
+	  {(tagId != null && tagScope == null) && (
+	      <div className="flex flex-wrap items-center gap-3 rounded-lg border
+			      border-amber-200 bg-amber-50 px-4 py-3 text-sm text-amber-900
+			      dark:border-amber-800 dark:bg-amber-950 dark:text-amber-100">
+		<span>選択中タグが見つかりません．</span>
+		<PrefetchLink
+		    to={clearedTagSelectionPath (location.search, materialFilter)}
+		    className="font-medium underline underline-offset-2
+			       text-amber-800 dark:text-amber-200">
+		  タグ選択を解除
+		</PrefetchLink>
+	      </div>)}
+
 	  {tagState === 'untagged' && (
 	      <PrefetchLink
 		  to={`/materials?material_filter=${ materialFilter }`}
@@ -395,7 +542,7 @@ const MaterialListPage: FC = () => {
 		      : [
 			  'border-stone-300 bg-white text-stone-900 dark:border-stone-700',
 			  'dark:bg-stone-900 dark:text-stone-100'].join (' ') }`}>
-		カード
+		アイコン
 	      </button>
 	      <button
 		  type="button"
@@ -408,7 +555,7 @@ const MaterialListPage: FC = () => {
 		      : [
 			  'border-stone-300 bg-white text-stone-900 dark:border-stone-700',
 			  'dark:bg-stone-900 dark:text-stone-100'].join (' ') }`}>
-		一覧
+		詳細
 	      </button>
 	    </div>
 
@@ -436,20 +583,22 @@ const MaterialListPage: FC = () => {
 	  {isError && (
 	      <p className="text-red-600 dark:text-red-300">素材一覧の取得に失敗しました．</p>)}
 	  {(!isLoading && !isError && materials.length === 0) && (
-	      <p>素材はありません．</p>)}
+	      <p>
+		素材はありません。
+		{(tagScope && ['character', 'material'].includes (tagScope.tag.category)) && (
+		    <>
+		      <PrefetchLink
+			  to={materialNewPath (tagScope.tag.name, location.pathname + location.search)}
+			  className="font-medium underline underline-offset-2
+				     text-sky-700 dark:text-sky-300">
+			追加してください
+		      </PrefetchLink>。
+		    </>)}
+	      </p>)}
 	  {materials.length > 0 && (
-	      view === 'card'
+	      groupBy === 'parent_tag' && groups.length > 0
-	      ? (
+	      ? renderGroupedMaterials (groups)
-		  <div className="grid grid-cols-[repeat(auto-fill,minmax(196px,1fr))]
+	      : renderMaterialCollection (materials))}
-				  justify-items-center gap-4">
-		    {materials.map (material => (
-			<MaterialCard key={material.id} material={material}/>))}
-		  </div>)
-	      : (
-		  <div className="space-y-3">
-		    {materials.map (material => (
-			<MaterialListItem key={material.id} material={material}/>))}
-		  </div>))}
 	  <Pagination page={page} totalPages={totalPages}/>
 	</div>
       </MainArea>)

frontend/src/pages/materials/MaterialNewPage.test.tsx

@@ -1,5 +1,6 @@
 import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { Route, Routes, useLocation } from 'react-router-dom'
 
 import MaterialNewPage from '@/pages/materials/MaterialNewPage'
 import { renderWithProviders } from '@/test/render'
@@ -17,6 +18,11 @@ const toastApi = vi.hoisted (() => ({
 vi.mock ('@/lib/api', () => api)
 vi.mock ('@/components/ui/use-toast', () => toastApi)
 
+const LocationView = () => {
+  const location = useLocation ()
+  return <div>{location.pathname + location.search}</div>
+}
+
 describe ('MaterialNewPage', () => {
   beforeEach (() => {
     vi.clearAllMocks ()
@@ -69,4 +75,50 @@ describe ('MaterialNewPage', () => {
     expect (await screen.findAllByText ('ファイルまたは URL は必須です．')).toHaveLength (2)
     expect (screen.getAllByRole ('textbox')[1]).toHaveAttribute ('aria-invalid', 'true')
   })
+
+  it ('returns only to safe material URLs after successful creation', async () => {
+    api.apiPost.mockResolvedValueOnce ({})
+
+    renderWithProviders (
+        <Routes>
+          <Route path="/materials/new" element={<MaterialNewPage/>}/>
+          <Route path="/materials" element={<LocationView/>}/>
+        </Routes>,
+        {
+          route:
+              '/materials/new?tag=%E8%99%B9%E5%A4%8F'
+              + '&return_to=%2Fmaterials%3Ftag_id%3D20',
+        },
+    )
+
+    fireEvent.change (screen.getAllByRole ('textbox')[1], {
+      target: { value: 'https://example.com/ref' },
+    })
+    fireEvent.click (screen.getByRole ('button', { name: '追加' }))
+
+    expect (await screen.findByText ('/materials?tag_id=20')).toBeInTheDocument ()
+  })
+
+  it ('ignores unsafe return_to values after successful creation', async () => {
+    api.apiPost.mockResolvedValueOnce ({})
+
+    renderWithProviders (
+        <Routes>
+          <Route path="/materials/new" element={<MaterialNewPage/>}/>
+          <Route path="/materials" element={<LocationView/>}/>
+        </Routes>,
+        {
+          route:
+              '/materials/new?tag=%E8%99%B9%E5%A4%8F'
+              + '&return_to=https%3A%2F%2Fexample.com%2Fevil',
+        },
+    )
+
+    fireEvent.change (screen.getAllByRole ('textbox')[1], {
+      target: { value: 'https://example.com/ref' },
+    })
+    fireEvent.click (screen.getByRole ('button', { name: '追加' }))
+
+    expect (await screen.findByText ('/materials')).toBeInTheDocument ()
+  })
 })

frontend/src/pages/materials/MaterialNewPage.tsx

@@ -27,6 +27,8 @@ const MaterialNewPage: FC = () => {
   const location = useLocation ()
   const query = new URLSearchParams (location.search)
   const tagQuery = query.get ('tag') ?? ''
+  const returnToQuery = query.get ('return_to') ?? ''
+  const safeReturnTo = returnToQuery.startsWith ('/materials') ? returnToQuery : ''
 
   const navigate = useNavigate ()
 
@@ -54,7 +56,7 @@ const MaterialNewPage: FC = () => {
       onSuccess: async () => {
 	await qc.invalidateQueries ({ queryKey: materialsKeys.root })
 	toast ({ title: '送信成功!' })
-	navigate (`/materials?tag=${ encodeURIComponent (tag) }`)
+	navigate (safeReturnTo || '/materials')
       },
       onError: error => {
 	applyValidationError (error)

frontend/src/pages/materials/MaterialSearchPage.tsx

@@ -1,51 +0,0 @@
-import { useState } from 'react'
-import { Helmet } from 'react-helmet-async'
-
-import FormField from '@/components/common/FormField'
-import PageTitle from '@/components/common/PageTitle'
-import TagInput from '@/components/common/TagInput'
-import MainArea from '@/components/layout/MainArea'
-import { SITE_TITLE } from '@/config'
-
-import type { FC, FormEvent } from 'react'
-
-
-const MaterialSearchPage: FC = () => {
-  const [tagName, setTagName] = useState ('')
-  const [parentTagName, setParentTagName] = useState ('')
-
-  const handleSearch = (e: FormEvent) => {
-    e.preventDefault ()
-  }
-
-  return (
-      <MainArea>
-	<Helmet>
-	  <title>素材集 | {SITE_TITLE}</title>
-	</Helmet>
-
-	<div className="max-w-xl">
-	  <PageTitle>素材集</PageTitle>
-
-	  <form onSubmit={handleSearch} className="space-y-2">
-	    {/* タグ */}
-	    <FormField label="タグ">
-	      {() => (
-		  <TagInput
-		      value={tagName}
-		      setValue={setTagName}/>)}
-	    </FormField>
-
-	    {/* 親タグ */}
-	    <FormField label="親タグ">
-	      {() => (
-		  <TagInput
-		      value={parentTagName}
-		      setValue={setParentTagName}/>)}
-	    </FormField>
-	  </form>
-	</div>
-      </MainArea>)
-}
-
-export default MaterialSearchPage

frontend/src/pages/materials/MaterialSyncSuppressionsPage.tsx

@@ -2,17 +2,13 @@ import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
 import { useState } from 'react'
 import { Helmet } from 'react-helmet-async'
 
-import PrefetchLink from '@/components/PrefetchLink'
 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 {
+import { createMaterialSyncSuppression, fetchMaterialSyncSuppressions } from '@/lib/materials'
-    createMaterialSyncSuppression,
-    fetchMaterialSyncSuppressions,
-} from '@/lib/materials'
 import { materialsKeys } from '@/lib/queryKeys'
 import { dateString, inputClass } from '@/lib/utils'
 
@@ -22,11 +18,11 @@ import type { MaterialSyncSuppressionSourceKind } from '@/types'
 
 const SOURCE_KIND_LABELS: Record<MaterialSyncSuppressionSourceKind, string> = {
     uri:               'URI',
-    google_drive_path: 'Google Drive path',
+    google_drive_path: 'Google Drive ファイル',
-    google_drive_path_prefix: 'Google Drive path prefix',
+    google_drive_path_prefix: 'Google Drive フォルダ',
-    google_drive_file: 'Google Drive file ID',
+    google_drive_file: 'Google Drive ファイル Id.',
-    legacy_drive_path: 'Legacy Drive path',
+    legacy_drive_path: '汎用ファイル',
-    legacy_drive_path_prefix: 'Legacy Drive path prefix'}
+    legacy_drive_path_prefix: '汎用フォルダ' }
 
 const REASONS = [
     'copyright_high_risk',
@@ -36,7 +32,23 @@ const REASONS = [
     'malware_or_dangerous_file',
     'duplicate_or_low_quality',
     'source_owner_request',
-    'other']
+    'other'] as const
+
+type MaterialSyncSuppressionReason = typeof REASONS[number]
+
+const REASON_NAMES: Record<MaterialSyncSuppressionReason, string> = {
+    ['copyright_high_risk']: '著作権への懸念',
+    ['copyright_takedown']: '著作者からの申出',
+    ['adult_or_sensitive']: '成人向け',
+    ['personal_information']: '個人情報',
+    ['malware_or_dangerous_file']: '危険なソフトウェア',
+    ['duplicate_or_low_quality']: '重複',
+    ['source_owner_request']: '同期元管理者からの申出',
+    ['other']: 'その他' } as const
+
+
+const reasonName = (reason: string): string =>
+    REASON_NAMES[reason as MaterialSyncSuppressionReason] ?? reason
 
 
 const MaterialSyncSuppressionsPage: FC = () => {
@@ -46,7 +58,7 @@ const MaterialSyncSuppressionsPage: FC = () => {
   const [sourceUri, setSourceUri] = useState ('')
   const [drivePath, setDrivePath] = useState ('')
   const [driveFileId, setDriveFileId] = useState ('')
-  const [reason, setReason] = useState (REASONS[0])
+  const [reason, setReason] = useState<MaterialSyncSuppressionReason> (REASONS[0])
 
   const { data, isError, isLoading } = useQuery ({
       queryKey: materialsKeys.suppressions (),
@@ -82,18 +94,11 @@ const MaterialSyncSuppressionsPage: FC = () => {
   return (
       <MainArea>
 	<Helmet>
-	  <title>{`同期元抑止 | ${ SITE_TITLE }`}</title>
+	  <title>{`素材同期抑止 | ${ SITE_TITLE }`}</title>
 	</Helmet>
 
 	<div className="space-y-5">
-	  <div className="flex flex-wrap items-center justify-between gap-3">
+	  <PageTitle>同期抑止</PageTitle>
-	    <PageTitle>同期元抑止</PageTitle>
-	    <PrefetchLink
-		to="/materials"
-		className="text-sm text-sky-700 underline underline-offset-2 dark:text-sky-300">
-	      素材一覧へ戻る
-	    </PrefetchLink>
-	  </div>
 
 	  <form
 	      onSubmit={handleSubmit}
@@ -115,7 +120,7 @@ const MaterialSyncSuppressionsPage: FC = () => {
 		    </select>)}
 	      </FormField>
 
-	      <FormField label="Source URI">
+	      <FormField label="同期元 URI">
 		{({ invalid }) => (
 		    <input
 			type="text"
@@ -124,7 +129,7 @@ const MaterialSyncSuppressionsPage: FC = () => {
 			className={inputClass (invalid)}/>)}
 	      </FormField>
 
-	      <FormField label="Drive path">
+	      <FormField label="Google Drive パス">
 		{({ invalid }) => (
 		    <input
 			type="text"
@@ -133,7 +138,7 @@ const MaterialSyncSuppressionsPage: FC = () => {
 			className={inputClass (invalid)}/>)}
 	      </FormField>
 
-	      <FormField label="Drive file ID">
+	      <FormField label="Google Drive ファイル Id.">
 		{({ invalid }) => (
 		    <input
 			type="text"
@@ -142,15 +147,15 @@ const MaterialSyncSuppressionsPage: FC = () => {
 			className={inputClass (invalid)}/>)}
 	      </FormField>
 
-	      <FormField label="理由">
+	      <FormField label="事由">
 		{({ invalid }) => (
 		    <select
 			value={reason}
-			onChange={e => setReason (e.target.value)}
+			onChange={e => setReason (e.target.value as MaterialSyncSuppressionReason)}
 			className={inputClass (invalid)}>
 		      {REASONS.map (value => (
 			  <option key={value} value={value}>
-			    {value}
+			    {REASON_NAMES[value]}
 			  </option>))}
 		    </select>)}
 	      </FormField>
@@ -185,7 +190,8 @@ const MaterialSyncSuppressionsPage: FC = () => {
 		    {suppression.normalizedSourceKey}
 		  </div>
 		  <div className="mt-2 text-sm text-stone-600 dark:text-stone-400">
-		    理由: {suppression.reason} / 登録: {dateString (suppression.createdAt)}
+		    事由: {reasonName (suppression.reason)} /
+		    登録: {dateString (suppression.createdAt)}
 		  </div>
 		</article>))}
 	  </div>

frontend/src/types.ts

@@ -88,12 +88,26 @@ export type MaterialIndexSort =
 
 export type MaterialIndexTagState = 'all' | 'tagged' | 'untagged'
 
+export type MaterialIndexGroupBy = 'none' | 'parent_tag'
+
 export type MaterialIndexView = 'card' | 'list'
 
+export type MaterialTagScope = {
+    tag:                {
+	id:          number
+	name:        string
+	category:    Category
+    }
+    includeDescendants: boolean
+}
+
 export type FetchMaterialsParams = {
     q:            string
     tagState:     MaterialIndexTagState
     mediaKind:    MaterialIndexMediaKind
+    tagId:        number | null
+    includeDescendants: boolean
+    groupBy:      MaterialIndexGroupBy
     createdFrom:  string
     createdTo:    string
     updatedFrom:  string
@@ -170,6 +184,23 @@ export type MaterialExportItem = {
     exportPath:  string
     enabled:     boolean }
 
+export type MaterialIndexGroup = {
+    key:         string
+    tag:         {
+	id:          number
+	name:        string
+	category:    Category
+    }
+    materialIds: number[]
+    count:       number }
+
+export type MaterialIndexResponse = {
+    materials: Material[]
+    count:     number
+    groups?:   MaterialIndexGroup[]
+    tagScope?: MaterialTagScope | null
+}
+
 export type MaterialVersion = {
     id:               number
     materialId:       number
@@ -179,6 +210,11 @@ export type MaterialVersion = {
     tagName:          string | null
     tagCategory:      Category | null
     url:              string | null
+    sourceKind:       string | null
+    sourceUri:        string | null
+    sourcePath:       string | null
+    sourceFileId:     string | null
+    normalizedSourceKey: string | null
     fileBlobId:       number | null
     fileFilename:     string | null
     fileContentType:  string | null