WIP: preserve Issue #479 changes

Refs #454

## Automated implementation (requires human review)
[SidebarComponent.tsx](frontend/src/components/layout/SidebarComponent.tsx) の1行を修正しました。`overflow-y-auto` を `md` 以上に限定し、スマホでサゼストがサイドバーの領域外で切られる原因を取り除きました。

差分を確認済みです。指定に従い、テスト・lint・ビルドは未実行です。実画面でのスマホ表示とPC表示の確認も未実施です。

## Automated review (not a guarantee of correctness)
```text
The change restricts sidebar scrolling to medium and larger viewports. No actionable regression was identified in the current diff.

```

## Verification
- Tests/builds/migrations were not authorized and were not invoked by the controller.
- Codex was instructed not to run them; its command transcript should be inspected.
- Do not merge before manual acceptance and required checks.

---------

Co-authored-by: Codex Night Worker <codex-night@localhost>
Reviewed-on: #456
Co-authored-by: テツノニジカ <969+codex-bot@noreply.localhost>

backend/AGENTS.md

@@ -424,7 +424,7 @@ races according to the target constraint's business meaning.
   and JSON keys are generally snake_case.
 - Preserve existing HTTP status conventions:
   `:unauthorized` for no user, `:forbidden` for insufficient role or banned
-  user, `:not_found` for missing records, and `:unprocessable_entity` for
+  user, `:not_found` for missing records, and `:unprocessable_content` for
   validation failures.
 - For diagnostic or internal helper JSON, prefer a deliberately light response
   shape over full representation classes when callers only need identifiers,

backend/Gemfile

@@ -71,3 +71,5 @@ gem "rspec-rails", "~> 8.0", :groups => [:development, :test]
 gem 'aws-sdk-s3', require: false
 
 gem 'rails-i18n', '~> 8.0.0'
+
+gem "json", "~> 2.19.9"

backend/Gemfile.lock

@@ -1,29 +1,29 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    actioncable (8.0.2)
-      actionpack (= 8.0.2)
-      activesupport (= 8.0.2)
+    actioncable (8.0.5.1)
+      actionpack (= 8.0.5.1)
+      activesupport (= 8.0.5.1)
       nio4r (~> 2.0)
       websocket-driver (>= 0.6.1)
       zeitwerk (~> 2.6)
-    actionmailbox (8.0.2)
-      actionpack (= 8.0.2)
-      activejob (= 8.0.2)
-      activerecord (= 8.0.2)
-      activestorage (= 8.0.2)
-      activesupport (= 8.0.2)
+    actionmailbox (8.0.5.1)
+      actionpack (= 8.0.5.1)
+      activejob (= 8.0.5.1)
+      activerecord (= 8.0.5.1)
+      activestorage (= 8.0.5.1)
+      activesupport (= 8.0.5.1)
       mail (>= 2.8.0)
-    actionmailer (8.0.2)
-      actionpack (= 8.0.2)
-      actionview (= 8.0.2)
-      activejob (= 8.0.2)
-      activesupport (= 8.0.2)
+    actionmailer (8.0.5.1)
+      actionpack (= 8.0.5.1)
+      actionview (= 8.0.5.1)
+      activejob (= 8.0.5.1)
+      activesupport (= 8.0.5.1)
       mail (>= 2.8.0)
       rails-dom-testing (~> 2.2)
-    actionpack (8.0.2)
-      actionview (= 8.0.2)
-      activesupport (= 8.0.2)
+    actionpack (8.0.5.1)
+      actionview (= 8.0.5.1)
+      activesupport (= 8.0.5.1)
       nokogiri (>= 1.8.5)
       rack (>= 2.2.4)
       rack-session (>= 1.0.1)
@@ -31,35 +31,35 @@ GEM
       rails-dom-testing (~> 2.2)
       rails-html-sanitizer (~> 1.6)
       useragent (~> 0.16)
-    actiontext (8.0.2)
-      actionpack (= 8.0.2)
-      activerecord (= 8.0.2)
-      activestorage (= 8.0.2)
-      activesupport (= 8.0.2)
+    actiontext (8.0.5.1)
+      actionpack (= 8.0.5.1)
+      activerecord (= 8.0.5.1)
+      activestorage (= 8.0.5.1)
+      activesupport (= 8.0.5.1)
       globalid (>= 0.6.0)
       nokogiri (>= 1.8.5)
-    actionview (8.0.2)
-      activesupport (= 8.0.2)
+    actionview (8.0.5.1)
+      activesupport (= 8.0.5.1)
       builder (~> 3.1)
       erubi (~> 1.11)
       rails-dom-testing (~> 2.2)
       rails-html-sanitizer (~> 1.6)
-    activejob (8.0.2)
-      activesupport (= 8.0.2)
+    activejob (8.0.5.1)
+      activesupport (= 8.0.5.1)
       globalid (>= 0.3.6)
-    activemodel (8.0.2)
-      activesupport (= 8.0.2)
-    activerecord (8.0.2)
-      activemodel (= 8.0.2)
-      activesupport (= 8.0.2)
+    activemodel (8.0.5.1)
+      activesupport (= 8.0.5.1)
+    activerecord (8.0.5.1)
+      activemodel (= 8.0.5.1)
+      activesupport (= 8.0.5.1)
       timeout (>= 0.4.0)
-    activestorage (8.0.2)
-      actionpack (= 8.0.2)
-      activejob (= 8.0.2)
-      activerecord (= 8.0.2)
-      activesupport (= 8.0.2)
+    activestorage (8.0.5.1)
+      actionpack (= 8.0.5.1)
+      activejob (= 8.0.5.1)
+      activerecord (= 8.0.5.1)
+      activesupport (= 8.0.5.1)
       marcel (~> 1.0)
-    activesupport (8.0.2)
+    activesupport (8.0.5.1)
       base64
       benchmark (>= 0.3)
       bigdecimal
@@ -92,22 +92,22 @@ GEM
       aws-sigv4 (~> 1.5)
     aws-sigv4 (1.12.1)
       aws-eventstream (~> 1, >= 1.0.2)
-    base64 (0.2.0)
+    base64 (0.3.0)
     bcrypt_pbkdf (1.1.1)
     bcrypt_pbkdf (1.1.1-arm64-darwin)
     bcrypt_pbkdf (1.1.1-x86_64-darwin)
-    benchmark (0.4.0)
-    bigdecimal (3.1.9)
+    benchmark (0.5.0)
+    bigdecimal (4.1.3)
     bootsnap (1.18.6)
       msgpack (~> 1.2)
     brakeman (7.0.2)
       racc
     builder (3.3.0)
     chronic (0.10.2)
-    concurrent-ruby (1.3.5)
-    connection_pool (2.5.3)
-    crass (1.0.6)
-    date (3.4.1)
+    concurrent-ruby (1.3.8)
+    connection_pool (3.0.2)
+    crass (1.0.7)
+    date (3.6.0)
     diff-lcs (1.6.2)
     discard (1.4.0)
       activerecord (>= 4.2, < 9.0)
@@ -115,8 +115,9 @@ GEM
     dotenv-rails (3.1.8)
       dotenv (= 3.1.8)
       railties (>= 6.1)
-    drb (2.2.1)
+    drb (2.2.3)
     ed25519 (1.4.0)
+    erb (6.0.7)
     erubi (1.13.1)
     factory_bot (6.5.6)
       activesupport (>= 6.1.0)
@@ -134,7 +135,7 @@ GEM
     gemojione (4.3.3)
       json
     github-markup (4.0.2)
-    globalid (1.2.1)
+    globalid (1.4.0)
       activesupport (>= 6.1)
     gollum (6.1.0)
       gemojione (~> 4.1)
@@ -166,19 +167,20 @@ GEM
     gollum-rugged_adapter (3.0)
       mime-types (~> 3.4)
       rugged (~> 1.5)
-    i18n (1.14.7)
+    i18n (1.15.2)
       concurrent-ruby (~> 1.0)
     image_processing (1.14.0)
       mini_magick (>= 4.9.5, < 6)
       ruby-vips (>= 2.0.17, < 3)
-    io-console (0.8.0)
-    irb (1.15.2)
+    io-console (0.9.4)
+    irb (1.18.0)
       pp (>= 0.6.0)
+      prism (>= 1.3.0)
       rdoc (>= 4.0.0)
       reline (>= 0.4.2)
     jmespath (1.6.2)
-    json (2.12.0)
-    jwt (2.10.1)
+    json (2.19.9)
+    jwt (3.3.0)
       base64
     kamal (2.6.1)
       activesupport (>= 7.0)
@@ -198,15 +200,16 @@ GEM
     language_server-protocol (3.17.0.5)
     lint_roller (1.1.0)
     logger (1.7.0)
-    loofah (2.24.1)
+    loofah (2.25.2)
       crass (~> 1.0.2)
       nokogiri (>= 1.12.0)
-    mail (2.8.1)
+    mail (2.9.1)
+      logger
       mini_mime (>= 0.1.1)
       net-imap
       net-pop
       net-smtp
-    marcel (1.0.4)
+    marcel (1.2.1)
     mime-types (3.7.0)
       logger
       mime-types-data (~> 3.2025, >= 3.2025.0507)
@@ -215,45 +218,46 @@ GEM
       benchmark
       logger
     mini_mime (1.1.5)
-    minitest (5.25.5)
-    msgpack (1.8.0)
-    multi_json (1.15.0)
+    minitest (6.0.6)
+      drb (~> 2.0)
+      prism (~> 1.5)
+    msgpack (1.8.5)
+    multi_json (1.21.2)
     mustache (1.1.1)
     mustache-sinatra (2.0.0)
       mustache (~> 1.0)
-    mustermann (3.0.3)
-      ruby2_keywords (~> 0.0.1)
+    mustermann (3.1.1)
     mysql2 (0.5.6)
-    net-imap (0.5.8)
+    net-imap (0.6.8)
       date
       net-protocol
     net-pop (0.1.2)
       net-protocol
-    net-protocol (0.2.2)
+    net-protocol (0.4.0)
       timeout
     net-scp (4.1.0)
       net-ssh (>= 2.6.5, < 8.0.0)
     net-sftp (4.0.0)
       net-ssh (>= 5.0.0, < 8.0.0)
-    net-smtp (0.5.1)
+    net-smtp (0.5.2)
       net-protocol
     net-ssh (7.3.0)
-    nio4r (2.7.4)
-    nokogiri (1.18.8-aarch64-linux-gnu)
+    nio4r (2.7.5)
+    nokogiri (1.19.4-aarch64-linux-gnu)
       racc (~> 1.4)
-    nokogiri (1.18.8-aarch64-linux-musl)
+    nokogiri (1.19.4-aarch64-linux-musl)
       racc (~> 1.4)
-    nokogiri (1.18.8-arm-linux-gnu)
+    nokogiri (1.19.4-arm-linux-gnu)
       racc (~> 1.4)
-    nokogiri (1.18.8-arm-linux-musl)
+    nokogiri (1.19.4-arm-linux-musl)
       racc (~> 1.4)
-    nokogiri (1.18.8-arm64-darwin)
+    nokogiri (1.19.4-arm64-darwin)
       racc (~> 1.4)
-    nokogiri (1.18.8-x86_64-darwin)
+    nokogiri (1.19.4-x86_64-darwin)
       racc (~> 1.4)
-    nokogiri (1.18.8-x86_64-linux-gnu)
+    nokogiri (1.19.4-x86_64-linux-gnu)
       racc (~> 1.4)
-    nokogiri (1.18.8-x86_64-linux-musl)
+    nokogiri (1.19.4-x86_64-linux-musl)
       racc (~> 1.4)
     octicons (19.15.2)
     ostruct (0.6.1)
@@ -261,70 +265,73 @@ GEM
     parser (3.3.8.0)
       ast (~> 2.4.1)
       racc
-    pp (0.6.2)
+    pp (0.6.4)
       prettyprint
-    prettyprint (0.2.0)
-    prism (1.4.0)
-    psych (5.2.6)
+    prettyprint (0.2.1)
+    prism (1.9.0)
+    psych (5.5.0)
       date
       stringio
     puma (6.6.0)
       nio4r (~> 2.0)
     racc (1.8.1)
-    rack (3.1.14)
+    rack (3.2.7)
     rack-cors (2.0.2)
       rack (>= 2.0.0)
-    rack-protection (4.1.1)
+    rack-protection (4.2.1)
       base64 (>= 0.1.0)
       logger (>= 1.6.0)
       rack (>= 3.0.0, < 4)
-    rack-session (2.1.1)
+    rack-session (2.1.2)
       base64 (>= 0.1.0)
       rack (>= 3.0.0)
-    rack-test (2.2.0)
+    rack-test (2.3.0)
       rack (>= 1.3)
-    rackup (2.2.1)
+    rackup (2.3.1)
       rack (>= 3)
-    rails (8.0.2)
-      actioncable (= 8.0.2)
-      actionmailbox (= 8.0.2)
-      actionmailer (= 8.0.2)
-      actionpack (= 8.0.2)
-      actiontext (= 8.0.2)
-      actionview (= 8.0.2)
-      activejob (= 8.0.2)
-      activemodel (= 8.0.2)
-      activerecord (= 8.0.2)
-      activestorage (= 8.0.2)
-      activesupport (= 8.0.2)
+    rails (8.0.5.1)
+      actioncable (= 8.0.5.1)
+      actionmailbox (= 8.0.5.1)
+      actionmailer (= 8.0.5.1)
+      actionpack (= 8.0.5.1)
+      actiontext (= 8.0.5.1)
+      actionview (= 8.0.5.1)
+      activejob (= 8.0.5.1)
+      activemodel (= 8.0.5.1)
+      activerecord (= 8.0.5.1)
+      activestorage (= 8.0.5.1)
+      activesupport (= 8.0.5.1)
       bundler (>= 1.15.0)
-      railties (= 8.0.2)
-    rails-dom-testing (2.2.0)
+      railties (= 8.0.5.1)
+    rails-dom-testing (2.3.0)
       activesupport (>= 5.0.0)
       minitest
       nokogiri (>= 1.6)
-    rails-html-sanitizer (1.6.2)
-      loofah (~> 2.21)
+    rails-html-sanitizer (1.7.1)
+      loofah (~> 2.25, >= 2.25.2)
       nokogiri (>= 1.15.7, != 1.16.7, != 1.16.6, != 1.16.5, != 1.16.4, != 1.16.3, != 1.16.2, != 1.16.1, != 1.16.0.rc1, != 1.16.0)
     rails-i18n (8.0.2)
       i18n (>= 0.7, < 2)
       railties (>= 8.0.0, < 9)
-    railties (8.0.2)
-      actionpack (= 8.0.2)
-      activesupport (= 8.0.2)
+    railties (8.0.5.1)
+      actionpack (= 8.0.5.1)
+      activesupport (= 8.0.5.1)
       irb (~> 1.13)
       rackup (>= 1.0.0)
       rake (>= 12.2)
       thor (~> 1.0, >= 1.2.2)
+      tsort (>= 0.2)
       zeitwerk (~> 2.6)
     rainbow (3.1.1)
-    rake (13.2.1)
-    rdoc (6.13.1)
+    rake (13.4.2)
+    rdoc (6.17.0)
+      erb
       psych (>= 4.0.0)
-    regexp_parser (2.10.0)
-    reline (0.6.1)
+      tsort
+    regexp_parser (2.13.1)
+    reline (0.7.0)
       io-console (~> 0.5)
-    rexml (3.4.1)
+    rexml (3.4.4)
     rouge (3.30.0)
     rspec-core (3.13.6)
       rspec-support (~> 3.13.0)
@@ -345,20 +352,20 @@ GEM
     rspec-support (3.13.6)
     rss (0.3.1)
       rexml
-    rubocop (1.75.6)
-      json (~> 2.3)
+    rubocop (1.92.0)
+      json (>= 2.3)
       language_server-protocol (~> 3.17.0.2)
       lint_roller (~> 1.1.0)
-      parallel (~> 1.10)
+      parallel (>= 1.10)
       parser (>= 3.3.0.2)
       rainbow (>= 2.2.2, < 4.0)
-      regexp_parser (>= 2.9.3, < 3.0)
-      rubocop-ast (>= 1.44.0, < 2.0)
+      regexp_parser (>= 2.11.3, < 3.0)
+      rubocop-ast (>= 1.49.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 2.4.0, < 4.0)
-    rubocop-ast (1.44.1)
+    rubocop-ast (1.50.0)
       parser (>= 3.3.7.2)
-      prism (~> 1.4)
+      prism (~> 1.7)
     rubocop-performance (1.25.0)
       lint_roller (~> 1.1)
       rubocop (>= 1.75.0, < 2.0)
@@ -377,24 +384,23 @@ GEM
     ruby-vips (2.2.3)
       ffi (~> 1.12)
       logger
-    ruby2_keywords (0.0.5)
     rugged (1.9.0)
     securerandom (0.4.1)
-    sinatra (4.1.1)
+    sinatra (4.2.1)
       logger (>= 1.6.0)
       mustermann (~> 3.0)
       rack (>= 3.0.0, < 4)
-      rack-protection (= 4.1.1)
+      rack-protection (= 4.2.1)
       rack-session (>= 2.0.0, < 3)
       tilt (~> 2.0)
-    sinatra-contrib (4.1.1)
+    sinatra-contrib (4.2.1)
       multi_json (>= 0.0.2)
       mustermann (~> 3.0)
-      rack-protection (= 4.1.1)
-      sinatra (= 4.1.1)
+      rack-protection (= 4.2.1)
+      sinatra (= 4.2.1)
       tilt (~> 2.0)
-    sprockets (4.2.2)
-      concurrent-ruby (~> 1.0)
+    sprockets (4.4.1)
+      concurrent-ruby (~> 1.1)
       logger
       rack (>= 2.2.4, < 4)
     sprockets-helpers (1.4.0)
@@ -403,14 +409,14 @@ GEM
       actionpack (>= 6.1)
       activesupport (>= 6.1)
       sprockets (>= 3.0.0)
-    sqlite3 (2.6.0-aarch64-linux-gnu)
-    sqlite3 (2.6.0-aarch64-linux-musl)
-    sqlite3 (2.6.0-arm-linux-gnu)
-    sqlite3 (2.6.0-arm-linux-musl)
-    sqlite3 (2.6.0-arm64-darwin)
-    sqlite3 (2.6.0-x86_64-darwin)
-    sqlite3 (2.6.0-x86_64-linux-gnu)
-    sqlite3 (2.6.0-x86_64-linux-musl)
+    sqlite3 (2.10.1-aarch64-linux-gnu)
+    sqlite3 (2.10.1-aarch64-linux-musl)
+    sqlite3 (2.10.1-arm-linux-gnu)
+    sqlite3 (2.10.1-arm-linux-musl)
+    sqlite3 (2.10.1-arm64-darwin)
+    sqlite3 (2.10.1-x86_64-darwin)
+    sqlite3 (2.10.1-x86_64-linux-gnu)
+    sqlite3 (2.10.1-x86_64-linux-musl)
     sshkit (1.24.0)
       base64
       logger
@@ -418,18 +424,19 @@ GEM
       net-sftp (>= 2.1.2)
       net-ssh (>= 2.8.0)
       ostruct
-    stringio (3.1.7)
+    stringio (3.2.0)
     therubyrhino (2.1.2)
       therubyrhino_jar (>= 1.7.4, < 1.7.9)
     therubyrhino_jar (1.7.8)
-    thor (1.3.2)
+    thor (1.5.0)
     thruster (0.1.13)
     thruster (0.1.13-aarch64-linux)
     thruster (0.1.13-arm64-darwin)
     thruster (0.1.13-x86_64-darwin)
     thruster (0.1.13-x86_64-linux)
-    tilt (2.6.0)
-    timeout (0.4.3)
+    tilt (2.9.0)
+    timeout (0.6.1)
+    tsort (0.2.0)
     twitter-text (1.14.7)
       unf (~> 0.1.0)
     tzinfo (2.0.6)
@@ -440,16 +447,16 @@ GEM
     unicode-display_width (3.1.4)
       unicode-emoji (~> 4.0, >= 4.0.4)
     unicode-emoji (4.0.4)
-    uri (1.0.3)
+    uri (1.1.2)
     useragent (0.16.11)
     webrick (1.9.1)
-    websocket-driver (0.7.7)
+    websocket-driver (0.8.2)
       base64
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
     whenever (1.0.0)
       chronic (>= 0.6.3)
-    zeitwerk (2.7.2)
+    zeitwerk (2.8.3)
 
 PLATFORMS
   aarch64-linux
@@ -473,6 +480,7 @@ DEPENDENCIES
   factory_bot_rails
   gollum
   image_processing (~> 1.14)
+  json (~> 2.19.9)
   jwt
   kamal
   mysql2 (~> 0.5.6)

backend/app/controllers/application_controller.rb

@@ -95,7 +95,7 @@ class ApplicationController < ActionController::API
     render_validation_error base: ['すでに存在してゐます．']
   end
 
-  def render_validation_error record = nil, fields: { }, base: [], status: :unprocessable_entity
+  def render_validation_error record = nil, fields: { }, base: [], status: :unprocessable_content
     errors = { }
 
     if record

backend/app/controllers/counts_exports_controller.rb

@@ -18,7 +18,7 @@ class CountsExportsController < ApplicationController
     render json: { error: 'private_condition' }, status: :forbidden
   rescue CountsTableQuery::TooManyColumns
     render json: { error: 'too_many_columns', max_columns: CountsTableQuery::MAX_COLUMNS },
-           status: :unprocessable_entity
+           status: :unprocessable_content
   rescue ActiveRecord::StatementTimeout
     render json: { error: 'counts_query_timeout' }, status: :service_unavailable
   rescue ArgumentError, TypeError, KeyError, JSON::ParserError
@@ -63,7 +63,7 @@ class CountsExportsController < ApplicationController
     render json: { error: 'private_condition' }, status: :forbidden
   rescue CountsTableQuery::TooManyColumns
     render json: { error: 'too_many_columns', max_columns: CountsTableQuery::MAX_COLUMNS },
-        status: :unprocessable_entity
+        status: :unprocessable_content
   rescue ActiveRecord::StatementTimeout
     render json: { error: 'counts_query_timeout' }, status: :service_unavailable
   rescue ArgumentError, TypeError, KeyError, JSON::ParserError
@@ -107,7 +107,7 @@ class CountsExportsController < ApplicationController
     render json: { error: 'private_condition' }, status: :forbidden
   rescue CountsTableQuery::TooManyColumns
     render json: { error: 'too_many_columns', max_columns: CountsTableQuery::MAX_COLUMNS },
-        status: :unprocessable_entity
+        status: :unprocessable_content
   rescue ActiveRecord::StatementTimeout
     render json: { error: 'counts_query_timeout' }, status: :service_unavailable
   rescue ArgumentError, TypeError, KeyError, JSON::ParserError

backend/app/controllers/counts_tables_controller.rb

@@ -24,7 +24,7 @@ class CountsTablesController < ApplicationController
     render json: { error: 'private_condition' }, status: :forbidden
   rescue CountsTableQuery::TooManyColumns
     render json: { error: 'too_many_columns', max_columns: CountsTableQuery::MAX_COLUMNS },
-           status: :unprocessable_entity
+           status: :unprocessable_content
   rescue CountsPivotTotals::TimedOut
     Rails.logger.warn('counts_query_timeout: pivot_totals')
     render json: { error: 'counts_query_timeout', stage: 'totals',

backend/app/controllers/gekanator_games_controller.rb

@@ -15,7 +15,7 @@ class GekanatorGamesController < ApplicationController
         answers:)
 
     if game.invalid?
-      render json: { errors: game.errors.full_messages }, status: :unprocessable_entity
+      render json: { errors: game.errors.full_messages }, status: :unprocessable_content
       return
     end
 
@@ -31,7 +31,7 @@ class GekanatorGamesController < ApplicationController
       learned_example_count:
     }, status: :created
   rescue ActiveRecord::RecordInvalid => e
-    render json: { errors: e.record.errors.full_messages }, status: :unprocessable_entity
+    render json: { errors: e.record.errors.full_messages }, status: :unprocessable_content
   end
 
   def extra_questions

backend/app/controllers/materials_controller.rb

@@ -536,7 +536,7 @@ class MaterialsController < ApplicationController
                    errors: { },
                    base_errors: ['ZIP export に必要な素材ファイルが欠損しています．'],
                    missing_files: },
-           status: :unprocessable_entity
+           status: :unprocessable_content
   end
 
   def build_uploaded_material_blob! file, file_sha256

backend/app/controllers/post_versions_controller.rb

@@ -14,8 +14,9 @@ class PostVersionsController < ApplicationController
 
     offset = (page - 1) * limit
 
-    q = HistoryAccess.visible(version_scope)
+    q = HistoryAccess.visible(PostVersion.all)
     q = q.where('post_versions.post_id = ?', post_id) if post_id
+    q = q.with_previous_version if tag_id || external_tag_id
     if external_tag_id || (tag_id && !(Tag.exists?(id: tag_id)))
       q = q.where('JSON_CONTAINS(post_versions.tags_json,' +
                   "JSON_OBJECT('external_tag_id', #{ external_tag_id || tag_id })) " +
@@ -28,9 +29,12 @@ class PostVersionsController < ApplicationController
 
     count = q.except(:select, :order, :limit, :offset).count
 
-    versions = q.order(Arel.sql('post_versions.created_at DESC, post_versions.id DESC'))
+    ids = q.order(Arel.sql('post_versions.created_at DESC, post_versions.id DESC'))
                 .limit(limit)
                 .offset(offset)
+                .pluck('post_versions.id')
+    versions = version_scope.merge(q).where(id: ids)
+        .order(Arel.sql('post_versions.created_at DESC, post_versions.id DESC'))
 
     render json: { versions: serialise_versions(versions, locale.language_code), count:, population_count: HistoryAccess.population_count(PostVersion) }
   end

backend/app/controllers/posts_controller.rb

@@ -37,20 +37,10 @@ class PostsController < ApplicationController
 
     offset = (page - 1) * limit
 
-    pt_max_sql =
-        HistoryAccess.visible(PostVersion.all)
-        .select('post_id, MAX(created_at) AS max_updated_at')
-        .group('post_id')
-        .to_sql
-
-    updated_at_all_sql =
-        'GREATEST(posts.updated_at,' +
-        'COALESCE(pt_max.max_updated_at, posts.updated_at))'
+    needs_history_join = order[0] == 'updated_at' || updated_between.any?(&:present?)
 
     q =
         filtered_posts(locale)
-        .joins("LEFT JOIN (#{ pt_max_sql }) pt_max ON pt_max.post_id = posts.id")
-        .reselect('posts.*', Arel.sql("#{ updated_at_all_sql } AS updated_at_all"))
         .preload(:external_tags, :uploaded_user, :parents, :children,
                  post_tags: [:sections, { tag: [:deerjikists, :materials,
                                                 :tag_names, :tag_descriptions] }])
@@ -66,12 +56,25 @@ class PostsController < ApplicationController
     end
     q = q.where('posts.created_at >= ?', created_between[0]) if created_between[0]
     q = q.where('posts.created_at <= ?', created_between[1]) if created_between[1]
+    count_scope = q
+    if needs_history_join
+      history_times = HistoryAccess.visible(PostVersion.all)
+          .select('post_id, MAX(created_at) AS latest_at').group(:post_id)
+      q = q.joins("LEFT JOIN (#{ history_times.to_sql }) history_times " +
+                  'ON history_times.post_id = posts.id')
+      updated_at_all_sql = 'GREATEST(posts.updated_at, ' +
+          'COALESCE(history_times.latest_at, posts.updated_at))'
+    end
     if updated_between[0]
       q = q.where("#{ updated_at_all_sql } >= ?", updated_between[0])
     end
     if updated_between[1]
       q = q.where("#{ updated_at_all_sql } <= ?", updated_between[1])
     end
+    count_scope = q if updated_between.any?(&:present?)
+    if needs_history_join
+      q = q.select('posts.*', "#{ updated_at_all_sql } AS updated_at")
+    end
 
     sort_sql =
         case order[0]
@@ -88,12 +91,20 @@ class PostsController < ApplicationController
              .limit(limit)
              .offset(offset)
              .to_a
+    latest_version_times =
+        if needs_history_join
+          { }
+        else
+          HistoryAccess.visible(PostVersion.where(post_id: posts.map(&:id)))
+              .group(:post_id).maximum(:created_at)
+        end
 
-    q = q.except(:select, :order)
+    count_scope = count_scope.except(:select, :order)
 
     render json: { posts: posts.map { |post|
+      updated_at = [post.updated_at, latest_version_times[post.id]].compact.max
       PostRepr.base(post, language_code: locale.language_code)
-              .merge(updated_at: post.updated_at_all).tap do |json|
+          .merge('updated_at' => updated_at).tap do |json|
         json['thumbnail'] =
             if post.thumbnail.attached?
               rails_storage_proxy_url(post.thumbnail, only_path: false)
@@ -101,7 +112,7 @@ class PostsController < ApplicationController
               nil
             end
       end
-    }, count: q.group_values.present? ? q.count.size : q.count }
+    }, count: count_scope.group_values.present? ? count_scope.count.size : count_scope.count }
   end
 
   def random
@@ -418,7 +429,7 @@ class PostsController < ApplicationController
     filters = literals.map do |literal|
       internal, = source_ids.fetch(literal[:name])
       name = internal.empty? ? literal[:name] : names[internal.first]
-      return head :unprocessable_entity unless name && internal.length <= 1
+      return head :unprocessable_content unless name && internal.length <= 1
 
       literal[:negative] ? "not:#{ name }" : name
     end
@@ -427,7 +438,7 @@ class PostsController < ApplicationController
     literals.zip(translated).each do |literal, translation|
       unless (source_ids.fetch(literal[:name]).map(&:sort) ==
           target_ids.fetch(translation[:name]).map(&:sort))
-        return head :unprocessable_entity
+        return head :unprocessable_content
       end
     end
     index = 0

backend/app/controllers/theatres_controller.rb

@@ -55,7 +55,7 @@ class TheatresController < ApplicationController
     theatre = Theatre.find_by(id: params[:id])
     return head :not_found unless theatre
     requested_post_id = params[:post_id].to_i
-    return head :unprocessable_entity if requested_post_id <= 0
+    return head :unprocessable_content if requested_post_id <= 0
 
     skipped = false
     conflicted = false
@@ -95,7 +95,7 @@ class TheatresController < ApplicationController
     theatre = Theatre.find_by(id: params[:id])
     return head :not_found unless theatre
     requested_post_id = params[:post_id].to_i
-    return head :unprocessable_entity if requested_post_id <= 0
+    return head :unprocessable_content if requested_post_id <= 0
 
     conflicted = false
 

backend/app/models/history_access.rb

@@ -4,7 +4,7 @@ require 'digest'
 class HistoryAccess < ActiveSupport::CurrentAttributes
   attribute :user
   class Forbidden < StandardError; end
-  ARTIFACT_POLICY = 'counts-masked-summary-1'.freeze
+  ARTIFACT_POLICY = 'counts-private-predicates-4'.freeze
 
   KEYS = { 'post_versions' => ['post_id'], 'tag_versions' => ['tag_id'],
            'nico_tag_versions' => ['tag_id'],
@@ -59,20 +59,21 @@ class HistoryAccess < ActiveSupport::CurrentAttributes
   end
 
   def self.json_reference(table, key, document)
-    "NOT EXISTS (SELECT 1 FROM JSON_TABLE(COALESCE(#{ document }, JSON_ARRAY()), " +
+    # A scalar lookup avoids MySQL's semijoin rewrite losing the JSON row correlation.
+    "(SELECT 1 FROM JSON_TABLE(COALESCE(#{ document }, JSON_ARRAY()), " +
         "'$[*]' COLUMNS (reference_id BIGINT PATH '$' NULL ON EMPTY)) reference_entry " +
         "JOIN (#{ discarded_keys(table, key) }) blocked " +
-        "ON reference_entry.reference_id = blocked.#{ key })"
+        "ON reference_entry.reference_id = blocked.#{ key } LIMIT 1) IS NULL"
   end
 
   def self.list_reference(table, key, document)
     # Preserve FIND_IN_SET's exact token semantics, including empty tokens.
     array = "CONCAT('[', REPLACE(JSON_QUOTE(REPLACE(COALESCE(#{ document }, ''), " +
         "' ', ',')), ',', '\",\"'), ']')"
-    "NOT EXISTS (SELECT 1 FROM JSON_TABLE(#{ array }, '$[*]' " +
+    "(SELECT 1 FROM JSON_TABLE(#{ array }, '$[*]' " +
         "COLUMNS (reference_id VARCHAR(255) PATH '$')) reference_entry " +
         "JOIN (#{ discarded_keys(table, key) }) blocked " +
-        "ON reference_entry.reference_id = CAST(blocked.#{ key } AS CHAR))"
+        "ON reference_entry.reference_id = CAST(blocked.#{ key } AS CHAR) LIMIT 1) IS NULL"
   end
 
   def self.snapshot_reference(model, row, external: false)
@@ -91,8 +92,8 @@ class HistoryAccess < ActiveSupport::CurrentAttributes
       match += ' AND reference_version.version_no = tag_reference.version_no'
       latest = ''
     end
-    "NOT EXISTS (SELECT 1 FROM #{ source } JOIN #{ table } reference_version ON #{ match } " +
-        "WHERE NOT (#{ sql(model, 'reference_version') }) #{ latest })"
+    "(SELECT 1 FROM #{ source } JOIN #{ table } reference_version ON #{ match } " +
+        "WHERE NOT (#{ sql(model, 'reference_version') }) #{ latest } LIMIT 1) IS NULL"
   end
 
   def self.reference_sql(table, row)
@@ -109,11 +110,15 @@ class HistoryAccess < ActiveSupport::CurrentAttributes
       # conservatively; never expose a private linked name through an external tag.
       names = "JSON_MERGE_PRESERVE(JSON_ARRAY(private_tag.name), " +
           "COALESCE(JSON_EXTRACT(private_tag.names, '$**.name'), JSON_ARRAY()))"
-      ["NOT EXISTS (SELECT 1 FROM tag_versions private_tag " +
+      # DISTINCT prevents merging this independent name set into the correlated scan.
+      # Keep byte-distinct names even when the column collation considers them equal.
+      private_names = 'SELECT DISTINCT private_name.name, ' +
+          'CAST(private_name.name AS BINARY) AS name_bytes FROM tag_versions private_tag ' +
           "JOIN (#{ discarded_keys('tag_versions', 'tag_id') }) blocked " +
-          "ON blocked.tag_id = private_tag.tag_id " +
+          'ON blocked.tag_id = private_tag.tag_id ' +
           "JOIN JSON_TABLE(#{ names }, '$[*]' COLUMNS (name TEXT PATH '$')) private_name " +
-          "WHERE private_name.name <> '' AND " +
+          "WHERE private_name.name <> ''"
+      ["NOT EXISTS (SELECT 1 FROM (#{ private_names }) private_name WHERE " +
           "LOCATE(CONCAT(' ', private_name.name, ' '), " +
           "CONCAT(' ', COALESCE(#{ row }.linked_tags, ''), ' ')) > 0)"]
     when 'tag_versions'

backend/app/services/counts_axes.rb

@@ -1,12 +1,41 @@
 class CountsAxes
   MAX_AXES = 8
+  MASKED_TEXT = '********'.freeze
   MASKED_VALUE = '__counts_private__'.freeze
-  PUBLIC_FIELDS = ['created_at', 'event_type'].freeze
+  PUBLIC_FIELDS = ['resource_id', 'version_no', 'event_type', 'user',
+                   'created_at'].freeze
   class TooManyAxes < ArgumentError; end
   class PrivateCondition < ArgumentError; end
 
   GRAINS = ['year', 'quarter', 'month', 'week', 'day', 'hour'].freeze
 
+  def self.private_field?(field)
+    !PUBLIC_FIELDS.include?(field) && field != 'user.id'
+  end
+
+  def self.visible_ids_sql(definition)
+    "SELECT counts_visible.id FROM #{ definition.table } counts_visible WHERE " +
+        HistoryAccess.sql(definition.model, 'counts_visible')
+  end
+
+  def self.visibility_sql(definition, field)
+    return 'TRUE' if HistoryAccess.admin?
+
+    source = visible_ids_sql(definition)
+    visible = "v.id IN (#{ source })"
+    return visible unless field == 'changed_field'
+
+    "(#{ visible }) AND (previous.id IS NULL OR previous.id IN (#{ source }))"
+  end
+
+  def self.masked_sql(expression, definition, field)
+    return expression if HistoryAccess.admin? || !private_field?(field)
+
+    visible = visibility_sql(definition, field)
+    quoted = ApplicationRecord.connection.quote(MASKED_VALUE)
+    "CASE WHEN #{ visible } THEN #{ expression } ELSE #{ quoted } END"
+  end
+
   def self.time_expression(expression, grain, timezone)
     raise ArgumentError unless GRAINS.include?(grain)
 
@@ -60,13 +89,9 @@ class CountsAxes
         @definition.fields[field] == :datetime ? self.class.time_expression(
             expression, axis.fetch('grain', 'month'), @population.timezone) : expression
       end
-      if !HistoryAccess.admin? && !PUBLIC_FIELDS.include?(field)
-        visible = HistoryAccess.sql(@definition.model, 'v')
-        if field == 'changed_field'
-          visible = "(#{ visible }) AND (#{ HistoryAccess.sql(@definition.model, 'previous') })"
-        end
-        expression = "CASE WHEN #{ visible } " +
-            "THEN CAST((#{ expression }) AS CHAR) ELSE '#{ MASKED_VALUE }' END"
+      if !HistoryAccess.admin? && self.class.private_field?(field)
+        expression = self.class.masked_sql(
+            "CAST((#{ expression }) AS CHAR)", @definition, field)
       end
       expression
     end
@@ -77,10 +102,12 @@ class CountsAxes
     selected = indexes.map { "#{ expressions[_1] } AS a#{ _1 }" }
     identities = ['v.id']
     if rows.any? { _1['field'] == 'tags' }
-      # Raw identities stay inside COUNT; masked tag occurrences remain additive.
-      identities << "COALESCE(CONCAT('internal:', tag_entry.tag_id), " +
-          "CONCAT('external:', tag_entry.external_tag_id))"
-      identities << 'changed.field_key' if rows.any? { _1['field'] == 'changed_field' }
+      identities << self.class.masked_sql(
+          "COALESCE(CONCAT('internal:', tag_entry.tag_id), " +
+              "CONCAT('external:', tag_entry.external_tag_id))", @definition, 'tags')
+      if rows.any? { _1['field'] == 'changed_field' }
+        identities << self.class.masked_sql('changed.field_key', @definition, 'changed_field')
+      end
     end
     members = identities.each_index.map { "counts_member_#{ _1 }" }
     selected += identities.each_with_index.map { |expression, index|
@@ -98,8 +125,17 @@ class CountsAxes
   def joins(fields = all.map { _1['field'] })
     result = ''
     if fields.include?('tags')
+      document = 'CAST(v.tags_json AS JSON)'
+      unless HistoryAccess.admin?
+        visible = self.class.visible_ids_sql(@definition)
+        result += " LEFT JOIN (#{ visible }) counts_tags_visible " +
+            'ON counts_tags_visible.id = v.id '
+        document = "CASE WHEN counts_tags_visible.id IS NOT NULL " +
+            "THEN #{ document } ELSE JSON_ARRAY(" +
+            "JSON_OBJECT('tag_id', 0)) END"
+      end
       result += <<~SQL.squish
-         JOIN JSON_TABLE(CAST(v.tags_json AS JSON), '$[*]' COLUMNS (
+         JOIN JSON_TABLE(#{ document }, '$[*]' COLUMNS (
           tag_id BIGINT PATH '$.tag_id' NULL ON EMPTY,
           external_tag_id BIGINT PATH '$.external_tag_id' NULL ON EMPTY)) tag_entry
 
@@ -112,6 +148,13 @@ class CountsAxes
       condition = @definition.changes.map do |field|
         "(changed.field_key = '#{ field }' AND #{ @population.changed_sql(field) })"
       end.join(' OR ')
+      unless HistoryAccess.admin?
+        visible = self.class.visibility_sql(@definition, 'changed_field')
+        marker = ApplicationRecord.connection.quote(MASKED_VALUE)
+        fields += " UNION ALL SELECT #{ marker } AS field_key"
+        condition = "((#{ visible }) AND (#{ condition })) OR " +
+            "(NOT (#{ visible }) AND changed.field_key = #{ marker })"
+      end
       result += " JOIN (#{ fields }) changed ON (#{ condition })"
     end
     result

backend/app/services/counts_condition.rb

@@ -82,14 +82,32 @@ class CountsCondition
 
   def apply(scope, entry)
     raise ArgumentError unless entry.is_a?(Hash)
+
     if entry['operator'] == 'axis_eq'
       raise ArgumentError unless (entry.keys - ['field', 'operator', 'grain', 'value']).empty?
       value = entry['value']
-      unless value.nil? || value.is_a?(String) || value.is_a?(Numeric) || [true, false].include?(value)
+      unless (value.nil? || value.is_a?(String) || value.is_a?(Numeric) ||
+          [true, false].include?(value))
         raise ArgumentError
       end
       raise ArgumentError if value.is_a?(String) && value.bytesize > 8192
 
+      if (!HistoryAccess.admin? && CountsAxes.private_field?(entry['field']) &&
+          (value == CountsAxes::MASKED_VALUE ||
+              (value == CountsAxes::MASKED_TEXT &&
+                  (@definition.fields[entry['field']] != :string ||
+                      ['tags', 'changed_field'].include?(entry['field'])))))
+        field = entry.fetch('field')
+        raise ArgumentError unless @definition.axes(@population.history).include?(field)
+        if entry.key?('grain')
+          unless (@definition.fields[field] == :datetime &&
+              CountsAxes::GRAINS.include?(entry['grain']))
+            raise ArgumentError
+          end
+        end
+        return scope.none
+      end
+      scope = @population.condition_scope(scope, entry.fetch('field'))
       return @population.axis_condition(scope, entry)
     end
     allowed = ['field', 'operator', 'value', 'end', 'blank', 'input', 'values']
@@ -111,6 +129,13 @@ class CountsCondition
 
     source, expression = source_for(field[:key])
     type = field[:type]
+    # Preserve typed input compatibility; display markers are never real typed values.
+    if (!HistoryAccess.admin? && CountsAxes.private_field?(field[:key]) &&
+        entry['value'] == CountsAxes::MASKED_TEXT && type != :string && !entry['blank'])
+      return scope.none unless entry['operator'] == 'ne'
+
+      return @population.condition_scope(scope, field[:key])
+    end
     blank = blank_sql(expression, type)
     if entry['blank']
       sql = if source && field[:collection]
@@ -119,6 +144,7 @@ class CountsCondition
               "NOT EXISTS (SELECT 1 FROM #{ source } WHERE NOT (#{ blank }))"
             else blank
             end
+      scope = @population.condition_scope(scope, field[:key])
       return scope.where(Arel.sql(sql))
     end
     if ['in', 'not_in', 'any', 'all', 'none'].include?(entry['operator'])
@@ -131,6 +157,7 @@ class CountsCondition
     validate_enum!(field[:key], parsed.first) if type == :enum
     operator = entry['operator']
     if type == :interval
+      scope = @population.condition_scope(scope, field[:key])
       return interval(scope, source, expression, parsed)
     end
     clauses = []
@@ -158,6 +185,7 @@ class CountsCondition
     elsif operator == 'ne'
       predicate = "(NOT (#{ predicate }) OR #{ blank })"
     end
+    scope = @population.condition_scope(scope, field[:key])
     scope.where(predicate, *binds)
   end
 
@@ -168,6 +196,13 @@ class CountsCondition
 
     values = entry['values']
     raise ArgumentError unless values.is_a?(Array) && values.length <= 100
+    if (!HistoryAccess.admin? && CountsAxes.private_field?(field[:key]) &&
+        values.include?(CountsAxes::MASKED_TEXT) &&
+        (field[:type] != :string || field[:set_type] == 'tag_reference'))
+      return scope.none if entry['operator'] == 'all'
+
+      values = values - [CountsAxes::MASKED_TEXT]
+    end
     raise ArgumentError if [entry['value'], entry['end']].any? { !_1.nil? && _1 != '' }
 
     parsed = values.map do |value|
@@ -191,7 +226,10 @@ class CountsCondition
 
     operator = entry['operator']
     if parsed.empty?
-      return ['in', 'any'].include?(operator) ? scope.none : scope
+      return scope.none if ['in', 'any'].include?(operator)
+      return scope if entry['values'].empty?
+
+      return @population.condition_scope(scope, field[:key])
     end
     source, expression = source_for(field[:key])
     if field[:set_type] == 'tag_reference'
@@ -212,6 +250,7 @@ class CountsCondition
       predicate = source ? "NOT #{ predicate }" :
           "(NOT #{ predicate } OR #{ blank_sql(expression, field[:type]) })"
     end
+    scope = @population.condition_scope(scope, field[:key])
     scope.where(predicate, *parsed)
   end
 

backend/app/services/counts_population.rb

@@ -70,6 +70,13 @@ class CountsPopulation
     @authorisation_flg ? HistoryAccess.sql(model, row) : 'TRUE'
   end
 
+  # Each predicate keeps its own visibility restriction, including OR branches.
+  def condition_scope(scope, field)
+    return scope if HistoryAccess.admin? || !CountsAxes.private_field?(field)
+
+    scope.where(Arel.sql(CountsAxes.visibility_sql(definition, field)))
+  end
+
   def axis_condition(scope, entry)
     raise CountsAxes::PrivateCondition if entry['value'] == CountsAxes::MASKED_VALUE
 
@@ -209,6 +216,7 @@ class CountsPopulation
   def apply_tags
     raise ArgumentError unless definition.resource == 'posts'
 
+    @scope = condition_scope(@scope, 'tags')
     if params['tag'].present?
       @scope = @scope.where(snapshot_membership(
           "#{ params.fetch('kind', 'internal') }:#{ params['tag'] }"))

backend/app/services/counts_table_export.rb

@@ -253,7 +253,7 @@ class CountsTableExport
   end
 
   def summary_value(value, index, page)
-    return '********' if value == CountsAxes::MASKED_VALUE
+    return CountsAxes::MASKED_TEXT if value == CountsAxes::MASKED_VALUE
 
     field = @query.axes.all.fetch(index).fetch('field')
     return @labels.fetch('bot', '') if field == 'user' && value.nil?

backend/app/services/counts_table_query.rb

@@ -220,19 +220,11 @@ class CountsTableQuery
 
   private
 
-  # Public timeline predicates may include hidden records. Private predicates must
-  # never become a count oracle, even when the selected axes themselves are public.
+  # Private predicates require visibility independently of their operator.
+  # Ordering/measure state must not select a server-only masked coordinate.
   def validate_summary_conditions!
     return if mode != 'summary' || HistoryAccess.admin?
 
-    fields = QueryState.records(@params, 'conditions') + QueryState.records(@params, 'drill')
-    private_fields = fields.any? { !CountsAxes::PUBLIC_FIELDS.include?(_1['field']) }
-    keys = ['tags', 'tag', 'kind', 'resource_id', 'user_id']
-    private_parameters = keys.any? do |key|
-      @params.any? { |name, value| (name == key || name.start_with?("#{ key }.")) && value != '' }
-    end
-    raise CountsAxes::PrivateCondition if private_fields || private_parameters
-
     ['column_order', 'measures'].each do |key|
       # Coordinates are compared only to already masked expressions, never raw
       # values. Public coordinates remain sortable; a guessed private ID cannot match.

backend/db/seeds.rb

@@ -9,8 +9,21 @@
 #   end
 
 ApplicationRecord.transaction do
-  Language.find_or_create_by!(code: 'ain') { _1.name = 'ain' }
-  Script.find_or_create_by!(code: 'Kana') { _1.name = 'Kana' }
+  Language.find_or_create_by!(code: 'ja') { _1.name = '日本語' }
+  Script.find_or_create_by!(code: 'Jpan') { _1.name = '漢字、仮名文字およびラテン文字' }
+  Region.find_or_create_by!(code: 392) do
+    _1.alpha_code = 'JP'
+    _1.name = '日本国'
+  end
+  Locale.find_or_create_by!(code: 'ja') do
+    _1.language_code = 'ja'
+    _1.script_code = 'Jpan'
+    _1.region_code = 392
+    _1.name = '日本語'
+  end
+
+  Language.find_or_create_by!(code: 'ain') { _1.name = 'ヤウンモシルン　アイヌ　イタㇰ' }
+  Script.find_or_create_by!(code: 'Kana') { _1.name = 'カナモジ　オヨビ　ラテンモジ' }
 end
 
 post_url_sanitisation_rules = [

backend/spec/requests/counts_masked_search_spec.rb

@@ -0,0 +1,196 @@
+require 'rails_helper'
+
+RSpec.describe 'Counts masked search', type: :request do
+  let!(:tag) { create(:tag, primary_name: '秘密のタグ') }
+  let(:actor) { create(:user, :member) }
+  let(:admin) { create(:user, :admin) }
+  let(:base) do
+    { 'resource' => 'tags', 'definition' => 'history', 'mode' => 'summary',
+      'locale' => 'ja', 'execution_at' => '2025-01-01T00:00:00Z',
+      'timezone' => 'UTC', 'rows' => '', 'cols' => '', 'sort' => '' }
+  end
+
+  before do
+    [1, 2].each do |number|
+      TagVersion.create!(tag:, version_no: number,
+          event_type: number == 1 ? 'create' : 'discard', name: '秘密のタグ',
+          category: 'general', aliases: '秘密の別名', parent_tag_ids: '',
+          names: { ja: { name: '秘密のタグ', script_code: 'Jpan', auto_generated: false,
+                        aliases: [{ name: '秘密の別名', script_code: 'Jpan' }] } },
+          created_by_user: actor, created_at: Time.utc(2023, number))
+    end
+  end
+
+  def query(extra = {})
+    get '/counts/query', params: base.merge(extra)
+    expect(response).to have_http_status(:ok), extra.inspect
+    response.parsed_body
+  end
+
+  def predicate(field, operator, value, index = 0)
+    prefix = "conditions.#{ index }"
+    result = { 'conditions' => '', "#{ prefix }.field" => field,
+               "#{ prefix }.operator" => operator }
+    if ['in', 'any', 'all', 'none', 'not_in'].include?(operator)
+      result.merge!("#{ prefix }.values" => '1', 'condition_values' => '',
+          "condition_values.#{ index }.condition" => index.to_s,
+          "condition_values.#{ index }.value_type" => 'string',
+          "condition_values.#{ index }.value" => value)
+    else
+      result["#{ prefix }.value"] = value
+    end
+    result
+  end
+
+  it 'rejects every name and alias predicate on private history' do
+    ['name', 'name_ja', 'names.name', 'aliases.name', 'names.aliases.name'].each do |field|
+      secret = field.include?('aliases') ? '秘密の別名' : '秘密のタグ'
+      multiple = !['name', 'name_ja'].include?(field)
+      operators = multiple ? ['any', 'all', 'none'] : ['in', 'not_in']
+      ['eq', 'ne', 'like', *operators].each do |operator|
+        [secret, '********', '%', ''].each do |value|
+          expected = (value == '' && ['eq', 'ne', 'like'].include?(operator)) ? 2 : 0
+          expect(query(predicate(field, operator, value))['count']).to eq(expected)
+        end
+      end
+      blank = predicate(field, 'eq', '').merge('conditions.0.blank' => '1')
+      expect(query(blank)['count']).to eq(0)
+    end
+  end
+
+  it 'ignores missing and empty scalar values unless blank is checked' do
+    ['name', 'name_ja', 'names.name', 'aliases.name'].each do |field|
+      ['eq', 'ne', 'like'].each do |operator|
+        condition = predicate(field, operator, '')
+        [condition, condition.except('conditions.0.value')].each do |empty|
+          expect(query(empty)['count']).to eq(2)
+          expect(query(empty.merge('conditions.0.blank' => '0'))['count']).to eq(2)
+          expect(query(empty.merge('conditions.0.blank' => '1'))['count']).to eq(0)
+        end
+      end
+    end
+  end
+
+  it 'keeps details totals unchanged for inactive private predicates' do
+    settings = predicate('name', 'ne', '').merge('mode' => 'details')
+    result = query(settings)
+    expect(result['count']).to eq(0)
+    expect(result['versions']).to be_empty
+    expect(result['output_count']).to eq(2)
+    active = query(settings.merge('conditions.0.blank' => '1'))
+    expect(active['output_count']).to eq(0)
+  end
+
+  it 'ignores missing sets but preserves explicit empty set semantics' do
+    { 'name' => ['in', 'not_in'], 'aliases.name' => ['any', 'all', 'none'] }.each do
+        |field, operators|
+      operators.each do |operator|
+        condition = { 'conditions' => '', 'conditions.0.field' => field,
+                      'conditions.0.operator' => operator }
+        expect(query(condition)['count']).to eq(2)
+        empty = condition.merge('conditions.0.values' => '1', 'condition_values' => '')
+        expected = ['in', 'any'].include?(operator) ? 0 : 2
+        expect(query(empty)['count']).to eq(expected)
+        expect(query(condition.merge('conditions.0.blank' => '1'))['count']).to eq(0)
+        # An explicit empty string element is a real value, not an unspecified set.
+        expect(query(predicate(field, operator, ''))['count']).to eq(0)
+      end
+    end
+  end
+
+  it 'ignores empty private predicates regardless of their position' do
+    first = predicate('name', 'ne', '')
+        .merge(predicate('resource_id', 'eq', tag.id.to_s, 1))
+    last = predicate('resource_id', 'eq', tag.id.to_s)
+        .merge(predicate('aliases.name', 'like', '', 1))
+    expect(query(first)['count']).to eq(2)
+    expect(query(last)['count']).to eq(2)
+    active = predicate('name', 'ne', 'unrelated')
+        .merge(predicate('aliases.name', 'like', '', 1))
+    expect(query(active)['count']).to eq(0)
+  end
+
+  it 'searches public literal markers and treats axis predicates as explicit' do
+    public_tag = create(:tag, primary_name: '********')
+    TagVersion.create!(tag: public_tag, version_no: 1, event_type: 'create',
+        name: '********', category: 'general', aliases: '', parent_tag_ids: '',
+        names: { ja: { name: '********', script_code: 'Jpan', auto_generated: false,
+                      aliases: [] } }, created_at: Time.utc(2023))
+    expect(query['count']).to eq(3)
+    ['eq', 'ne', 'like', 'in', 'not_in'].each do |operator|
+      expected = ['ne', 'not_in'].include?(operator) ? 0 : 1
+      expect(query(predicate('name', operator, '********'))['count']).to eq(expected)
+    end
+    blank = predicate('aliases.name', 'eq', '').merge('conditions.0.blank' => '1')
+    expect(query(blank)['count']).to eq(1)
+    ['********', '', nil].each do |value|
+      condition = { 'conditions' => '', 'conditions.0.field' => 'name',
+                    'conditions.0.operator' => 'axis_eq',
+                    'conditions.0.value_type' => value.nil? ? 'null' : 'string' }
+      condition['conditions.0.value'] = value unless value.nil?
+      expected = value == '********' ? 1 : 0
+      expect(query(condition)['count']).to eq(expected)
+      drill = { 'drill' => '', 'drill.0.field' => 'name',
+                'drill.0.value_type' => value.nil? ? 'null' : 'string' }
+      drill['drill.0.value'] = value unless value.nil?
+      expect(query(drill)['count']).to eq(expected)
+    end
+  end
+
+  it 'keeps public identity and timeline predicates searchable' do
+    expect(query['count']).to eq(2)
+    values = { 'resource_id' => tag.id.to_s, 'version_no' => '2',
+               'event_type' => 'discard', 'user' => actor.id.to_s,
+               'created_at' => '2023-02-01T00:00:00Z' }
+    values.each do |field, value|
+      expected = ['resource_id', 'user'].include?(field) ? 2 : 1
+      expect(query(predicate(field, 'eq', value))['count']).to eq(expected)
+    end
+    condition = predicate('name', 'ne', '秘密のタグ')
+        .merge(predicate('event_type', 'eq', 'discard', 1))
+    expect(query(condition)['count']).to eq(0)
+    expect(query(predicate('category', 'eq', '********'))['count']).to eq(0)
+    expect(query(predicate('category', 'eq', 'general'))['count']).to eq(0)
+  end
+
+  it 'keeps public predicates available after combining multiple conditions' do
+    condition = predicate('resource_id', 'eq', tag.id.to_s)
+        .merge(predicate('event_type', 'eq', 'discard', 1))
+    expect(query(condition)['count']).to eq(1)
+    condition.merge!(predicate('name', 'ne', 'unrelated', 2))
+    expect(query(condition)['count']).to eq(0)
+  end
+
+  it 'keeps real name searches for administrators and excludes private details' do
+    condition = predicate('name', 'eq', '秘密のタグ')
+    details = query(condition.merge('mode' => 'details'))
+    expect(details['versions']).to be_empty
+    expect(details['output_count']).to eq(0)
+    masked = query(predicate('name', 'eq', '********').merge('mode' => 'details'))
+    expect(masked['versions']).to be_empty
+    expect(masked['output_count']).to eq(0)
+    sign_in_as(admin)
+    expect(query(condition)['count']).to eq(2)
+    expect(query(condition.merge('mode' => 'details'))['versions'].length).to eq(2)
+  end
+
+  it 'rejects private names reached through a post tag snapshot' do
+    post = create(:post)
+    PostVersion.create!(post:, version_no: 1, event_type: 'create', title: 'post',
+        url: post.url, tags: '', parent_post_ids: '',
+        tags_json: [{ tag_id: tag.id, version_no: 1, name: '秘密のタグ',
+                     category: 'general', sections: [] }],
+        created_at: Time.utc(2024))
+    ['tags.name', 'tags.names.name', 'tags.name_ja'].each do |field|
+      ['eq', 'ne', 'like', 'any', 'all', 'none'].each do |operator|
+        ['秘密のタグ', '********', '%'].each do |value|
+          settings = predicate(field, operator, value).merge('resource' => 'posts')
+          expect(query(settings)['count']).to eq(0)
+        end
+      end
+      blank = predicate(field, 'eq', '').merge('resource' => 'posts',
+          'conditions.0.blank' => '1')
+      expect(query(blank)['count']).to eq(0)
+    end
+  end
+end

backend/spec/requests/counts_table_spec.rb

@@ -262,7 +262,7 @@ RSpec.describe 'Counts table API', type: :request do
           tags: '', tags_json: [], parent_post_ids: '', created_at: Time.utc(2024, 3))
     end
     get '/counts/query', params: base.merge(mode: 'summary', rows: '', cols: 'title', sort: '')
-    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response).to have_http_status(:unprocessable_content)
     expect(response.parsed_body).to eq('error' => 'too_many_columns', 'max_columns' => 100)
   end
 
@@ -354,15 +354,25 @@ RSpec.describe 'Counts table API', type: :request do
     expect(result['cells'].sum { _1['count'] }).to eq(4)
     expect(response.body).not_to include('hidden title')
     masked = query(mode: 'summary', rows: 'resource_id', cols: '')
-    expect(masked['cells'].map { _1['values'] }).to eq([[CountsAxes::MASKED_VALUE]])
+    expect(masked['cells'].map { _1['values'] }).to eq([[record.id]])
     expect(masked['cells'].first['count']).to eq(4)
     expect(query['versions']).to be_empty
   end
 
-  it 'rejects private summary predicates instead of exposing a count oracle' do
-    get '/counts/query', params: base.merge(mode: 'summary', resource_id: record.id.to_s)
-    expect(response).to have_http_status(:forbidden)
-    expect(json).to eq('error' => 'private_condition')
+  it 'allows public identity predicates without exposing private snapshot fields' do
+    PostVersion.create!(post: record, version_no: 4, event_type: 'discard',
+        url: record.url, title: 'hidden title', tags: '', tags_json: [],
+        parent_post_ids: '', created_at: Time.utc(2024, 3))
+
+    get '/counts/query', params: base.merge(mode: 'summary',
+        resource_id: record.id.to_s, rows: 'resource_id', cols: 'title')
+
+    expect(response).to have_http_status(:ok)
+    expect(json['count']).to eq(4)
+    expect(json['cells'].sum { _1['count'] }).to eq(4)
+    expect(json['cells'].map { _1['values'].last })
+        .to include(CountsAxes::MASKED_VALUE)
+    expect(response.body).not_to include('hidden title')
   end
 
   it 'reports the combined axis limit without replacing it with a generic 400' do

backend/spec/requests/error_responses_spec.rb

@@ -20,7 +20,7 @@ RSpec.describe 'error responses', type: :request do
 
       patch "/tags/#{ tag.id }", params: { category: 'nico' }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json).to include(
           'type' => 'validation_error',
           'message' => '入力内容を確認してください．',
@@ -37,7 +37,7 @@ RSpec.describe 'error responses', type: :request do
 
       put "/users/#{ user.id }", params: { name: 'a' * 256 }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json).to include(
           'type' => 'validation_error',
           'message' => '入力内容を確認してください．')

backend/spec/requests/gekanator_games_spec.rb

@@ -49,7 +49,7 @@ RSpec.describe 'Gekanator games API', type: :request do
           question_count: 4,
           answers: [{ question_id: 'tag:1', answer: 'no' }] }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
     end
 
     it 'returns unauthorized without a user' do

backend/spec/requests/gekanator_learning_spec.rb

@@ -126,7 +126,7 @@ RSpec.describe 'Gekanator learning API', type: :request do
         }
       }.not_to change { GekanatorGame.count }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
     end
 
     it 'stores a game result for a non-admin user' do
@@ -785,7 +785,7 @@ RSpec.describe 'Gekanator learning API', type: :request do
         }
       }.not_to change { GekanatorQuestionExample.count }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
     end
 
     it 'rejects non-accepted questions' do
@@ -805,7 +805,7 @@ RSpec.describe 'Gekanator learning API', type: :request do
         ]
       }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
     end
 
     it 'rejects non-post_similarity questions' do
@@ -829,7 +829,7 @@ RSpec.describe 'Gekanator learning API', type: :request do
         ]
       }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
     end
 
     it 'allows a non-admin user to answer extra questions for their own game' do

backend/spec/requests/locale_write_paths_spec.rb

@@ -55,7 +55,7 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
         deprecated: false, aliases: 'other_primary', parent_tags: '' }
 
     aggregate_failures do
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(other_primary.reload).to have_attributes(tag_id: other_tag.id, primary_flg: true)
       expect(TagName.where(tag: other_tag, language_code: 'ja', primary_flg: true))
           .to contain_exactly(other_primary)
@@ -289,7 +289,7 @@ RSpec.describe 'Locale propagation on write paths', type: :request do
           aliases: 'other_ainu_primary', parent_tags: '' }
 
       aggregate_failures do
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(other_primary.reload).to have_attributes(
             tag_id: other_tag.id, language_code: 'ain', primary_flg: true)
         expect(TagName.where(tag: other_tag, language_code: 'ain', primary_flg: true))

backend/spec/requests/materials_spec.rb

@@ -289,7 +289,7 @@ RSpec.describe 'Materials API', type: :request do
       it 'returns 422 when tag is blank' do
         post '/materials', params: { tag: '   ', file: dummy_upload }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(json.fetch('errors')).to include(
             'tag' => ['タグは必須です．'])
       end
@@ -297,7 +297,7 @@ RSpec.describe 'Materials API', type: :request do
       it 'returns 422 when both file and url are blank' do
         post '/materials', params: { tag: 'material_create_blank' }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(json.fetch('errors')).to include(
             'file' => ['ファイルまたは URL は必須です．'],
             'url' => ['ファイルまたは URL は必須です．'])
@@ -381,7 +381,7 @@ RSpec.describe 'Materials API', type: :request do
           file: dummy_upload
         }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
       end
 
       it 'persists url-only material' do
@@ -424,7 +424,7 @@ RSpec.describe 'Materials API', type: :request do
           }
         end.not_to change(Material, :count)
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(json.fetch('errors')).to include(
           'file' => ['抑止された素材です: copyright_high_risk']
         )
@@ -484,7 +484,7 @@ RSpec.describe 'Materials API', type: :request do
           file: dummy_upload
         }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(json.fetch('errors')).to include(
             'tag' => ['タグは必須です．'])
       end
@@ -695,7 +695,7 @@ RSpec.describe 'Materials API', type: :request do
           file: dummy_upload(filename: 'blocked.png', body: 'blocked-update')
         }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(material.reload.file.blob.filename.to_s).to eq('old.png')
       end
     end

backend/spec/requests/nico_tags_spec.rb

@@ -218,7 +218,7 @@ RSpec.describe 'NicoTags', type: :request do
 
       patch "/tags/nico/#{nico_tag.id}", params: { tags: 'nico:linked_ng' }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
           'tags' => ['ニコニコ・タグ同士は連携できません．'])
     end
@@ -239,7 +239,7 @@ RSpec.describe 'NicoTags', type: :request do
 
       expect([Tag.count, TagName.count, TagVersion.count]).to eq(before_counts)
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors').fetch('tags')).to include(
           a_string_including('タグ名 “invalid”:', '名前に使用できない文字が含まれてゐます．'))
     end

backend/spec/requests/post_history_privacy_spec.rb

@@ -0,0 +1,129 @@
+require 'rails_helper'
+
+RSpec.describe 'Post history privacy', type: :request do
+  let(:origin) { Time.utc(2020, 1, 1) }
+  let!(:post_record) do
+    create(:post, title: 'current', created_at: origin, updated_at: origin)
+  end
+  let!(:other_post) do
+    create(:post, created_at: origin, updated_at: origin + 3.days + 1.hour)
+  end
+  let!(:tag) { create(:tag, primary_name: 'private-history-tag') }
+  let!(:external) { create(:external_tag, name: 'external-history-tag') }
+
+  before do
+    ['create', 'discard'].each_with_index do |event, index|
+      TagVersion.create!(tag:, version_no: index + 1, event_type: event,
+          name: 'private-history-tag', category: 'general', aliases: '', parent_tag_ids: '',
+          names: { ja: { name: 'private-history-tag', script_code: 'Jpan',
+                         auto_generated: false, aliases: [] } },
+          created_at: origin + index.hours)
+    end
+    NicoTagVersion.create!(external_tag: external, version_no: 1, event_type: 'create',
+        name: 'nico:external-history-tag', linked_tags: 'private-history-tag',
+        created_at: origin)
+    ['create', 'discard', 'restore', 'update'].each_with_index do |event, index|
+      snapshots =
+          if index < 2
+            [{ tag_id: tag.id, version_no: 1, name: 'private-history-tag', sections: [] }]
+          elsif index == 3
+            [{ external_tag_id: external.id }]
+          else
+            []
+          end
+      PostVersion.create!(post: post_record, version_no: index + 1, event_type: event,
+          title: "version #{ index + 1 }", url: post_record.url, tags: '',
+          tags_json: snapshots, parent_post_ids: '', created_at: origin + (index + 1).days)
+    end
+  end
+
+  it 'evaluates each reference condition against the restored snapshot alone' do
+    HistoryAccess.set(user: nil) do
+      restored = PostVersion.where(post_id: post_record.id, version_no: 3)
+      HistoryAccess.reference_sql('post_versions', 'post_versions').each do |condition|
+        expect(restored.where(Arel.sql(condition)).pluck(:version_no)).to eq([3])
+      end
+      expect(HistoryAccess.visible(PostVersion.where(post_id: post_record.id))
+          .pluck(:version_no)).to eq([3])
+    end
+  end
+
+  it 'keeps every version through a later discard private after another restore' do
+    ['discard', 'restore'].each_with_index do |event, index|
+      PostVersion.create!(post: post_record, version_no: index + 5, event_type: event,
+          title: 'later snapshot', url: post_record.url, tags: '', tags_json: [],
+          parent_post_ids: '', created_at: origin + (index + 5).days)
+    end
+
+    get '/posts/versions', params: { post: post_record.id }
+
+    expect(response).to have_http_status(:ok)
+    expect(response.parsed_body.fetch('versions').pluck('version_no')).to eq([6])
+    expect(response.parsed_body.fetch('count')).to eq(1)
+    expect(response.parsed_body.fetch('versions').first.fetch('title').fetch('prev')).to be_nil
+  end
+
+  ['anonymous', 'member', 'admin'].each do |role|
+    context "as #{ role }" do
+      before do
+        sign_in_as(create(:user, role.to_sym)) unless role == 'anonymous'
+      end
+
+      it 'uses only authorised history timestamps for display' do
+        get '/posts'
+        expect(response).to have_http_status(:ok)
+        row = response.parsed_body.fetch('posts').find { _1.fetch('id') == post_record.id }
+        expected = origin + (role == 'admin' ? 4 : 3).days
+        expect(Time.zone.parse(row.fetch('updated_at'))).to eq(expected)
+      end
+
+      it 'uses the same visibility for date bounds and count' do
+        get '/posts', params: { updated_from: (origin + 4.days).iso8601,
+                                updated_to: (origin + 4.days).iso8601 }
+        expect(response).to have_http_status(:ok)
+        ids = response.parsed_body.fetch('posts').pluck('id')
+        expect(ids).to eq(role == 'admin' ? [post_record.id] : [])
+        expect(response.parsed_body.fetch('count')).to eq(ids.length)
+      end
+
+      it 'sorts using authorised timestamps in both directions' do
+        ['asc', 'desc'].each do |direction|
+          get '/posts', params: { order: "updated_at:#{ direction }" }
+          expect(response).to have_http_status(:ok)
+          expected = role == 'admin' ? [other_post.id, post_record.id] :
+              [post_record.id, other_post.id]
+          expected.reverse! if direction == 'desc'
+          expect(response.parsed_body.fetch('posts').pluck('id')).to eq(expected)
+        end
+      end
+
+      it 'applies authorised timestamp ordering before pagination' do
+        get '/posts', params: { order: 'updated_at:desc', limit: 1 }
+
+        expect(response).to have_http_status(:ok)
+        expected = role == 'admin' ? post_record.id : other_post.id
+        expect(response.parsed_body.fetch('posts').pluck('id')).to eq([expected])
+        expect(response.parsed_body.fetch('count')).to eq(2)
+      end
+
+      it 'counts only visible versions and masks a private previous version' do
+        get '/posts/versions', params: { post: post_record.id }
+        expect(response).to have_http_status(:ok)
+        body = response.parsed_body
+        expected = role == 'admin' ? [4, 3, 2, 1] : [3]
+        expect(body.fetch('count')).to eq(expected.length)
+        expect(body.fetch('versions').pluck('version_no')).to eq(expected)
+        restored = body.fetch('versions').find { _1.fetch('version_no') == 3 }
+        expect(restored.fetch('title').fetch('prev')).to eq(role == 'admin' ? 'version 2' : nil)
+      end
+
+      it 'uses only an authorised previous version for tag filtering' do
+        get '/posts/versions', params: { post: post_record.id, tag: tag.id }
+        expect(response).to have_http_status(:ok)
+        expected = role == 'admin' ? [3, 2, 1] : []
+        expect(response.parsed_body.fetch('versions').pluck('version_no')).to eq(expected)
+        expect(response.parsed_body.fetch('count')).to eq(expected.length)
+      end
+    end
+  end
+end

backend/spec/requests/post_locale_filter_identity_spec.rb

@@ -48,7 +48,7 @@ RSpec.describe 'Post filter identity across locales', type: :request do
     primary_tag_name_for(tag, 'ja').update_columns(name: 'nico:shared')
     get '/posts/tag_filters', params: {
         locale: 'ja', target_locale: 'ain-Kana', tags: 'nico:shared' }
-    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response).to have_http_status(:unprocessable_content)
   end
 
   it 'rejects removed reference parameters instead of overriding the name' do

backend/spec/requests/posts_spec.rb

@@ -629,6 +629,37 @@ RSpec.describe 'Posts API', type: :request do
         create(:post_tag, post: plain_post, tag:, created_at: t3)
       end
 
+      it 'displays history time after pagination without joining history to posts or count' do
+        queries = []
+        subscriber = ->(event) { queries << event.payload.fetch(:sql) }
+        ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') do
+          get '/posts', params: { url: '/version-time/', order: 'url:asc', limit: 1 }
+        end
+
+        expect(response).to have_http_status(:ok)
+        expect(json.fetch('posts').pluck('id')).to eq([history_post.id])
+        expect(Time.zone.parse(json.fetch('posts').first.fetch('updated_at'))).to eq(t2)
+        expect(json.fetch('count')).to eq(3)
+        post_queries = queries.select { _1.include?('FROM `posts`') }
+        expect(post_queries).not_to be_empty
+        expect(post_queries.grep(/post_versions/)).to be_empty
+      end
+
+      it 'omits the history aggregate from count when only sorting by update time' do
+        queries = []
+        subscriber = ->(event) { queries << event.payload.fetch(:sql) }
+        ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') do
+          get '/posts', params: { url: '/version-time/', order: 'updated_at:desc', limit: 1 }
+        end
+
+        expect(response).to have_http_status(:ok)
+        expect(json.fetch('posts').pluck('id')).to eq([newer_post.id])
+        expect(json.fetch('count')).to eq(3)
+        count_queries = queries.select { _1.include?('FROM `posts`') && _1.match?(/COUNT\(/i) }
+        expect(count_queries).not_to be_empty
+        expect(count_queries.grep(/post_versions/)).to be_empty
+      end
+
       ['asc', 'desc'].each do |direction|
         it "sorts by the later of post update and latest version time (#{ direction })" do
           get '/posts', params: { url: '/version-time/', order: "updated_at:#{ direction }" }
@@ -658,6 +689,16 @@ RSpec.describe 'Posts API', type: :request do
         expect(json.fetch('posts').map { |item| item.fetch('id') }).to eq([history_post.id])
         expect(json.fetch('count')).to eq(1)
       end
+
+      it 'counts every timestamp match before pagination' do
+        get '/posts', params: { url: '/version-time/', order: 'updated_at:asc',
+                               updated_from: t1.iso8601, updated_to: t3.iso8601,
+                               limit: 1, page: 2 }
+
+        expect(response).to have_http_status(:ok)
+        expect(json.fetch('posts').pluck('id')).to eq([history_post.id])
+        expect(json.fetch('count')).to eq(3)
+      end
     end
 
     context 'when original_created_from/original_created_to are provided' do
@@ -1001,7 +1042,7 @@ RSpec.describe 'Posts API', type: :request do
 
       get '/posts/metadata', params: { url: 'file:///etc/passwd' }
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to have_key('url')
     end
   end
@@ -1139,7 +1180,7 @@ RSpec.describe 'Posts API', type: :request do
         )
       }.not_to change(Post, :count)
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
         'thumbnail' => ['サムネイル画像の変換に失敗しました．']
       )
@@ -1178,7 +1219,7 @@ RSpec.describe 'Posts API', type: :request do
         thumbnail: dummy_upload
       )
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
         'tags' => ['廃止済みタグがあります: deprecated_direct_tag']
       )
@@ -1224,7 +1265,7 @@ RSpec.describe 'Posts API', type: :request do
         thumbnail: dummy_upload
       )
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json).to include(
         'type' => 'validation_error',
         'message' => '入力内容を確認してください．'
@@ -1292,7 +1333,7 @@ RSpec.describe 'Posts API', type: :request do
         thumbnail: dummy_upload
       )
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
         'video_ms' => ['タグ区間の終端が動画時間を超えてゐます．']
       )
@@ -1403,7 +1444,7 @@ RSpec.describe 'Posts API', type: :request do
         thumbnail: dummy_upload
       )
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
         'video_ms' => ['タグ区間の開始が動画時間以上です．']
       )
@@ -1424,7 +1465,7 @@ RSpec.describe 'Posts API', type: :request do
           thumbnail: dummy_upload
         )
 
-        expect(response).to have_http_status(:unprocessable_entity), response.body
+        expect(response).to have_http_status(:unprocessable_content), response.body
         expect(json).to include(
             'type' => 'validation_error',
             'message' => '入力内容を確認してください．',
@@ -1444,7 +1485,7 @@ RSpec.describe 'Posts API', type: :request do
             tags: 'spec_tag', # 既存タグ名を投げる
             thumbnail: dummy_upload)
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
       end
     end
 
@@ -1458,7 +1499,7 @@ RSpec.describe 'Posts API', type: :request do
             tags: 'spec_tag', # 既存タグ名を投げる
             thumbnail: dummy_upload)
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
       end
     end
 
@@ -1560,7 +1601,7 @@ RSpec.describe 'Posts API', type: :request do
               thumbnail: dummy_upload }
         }.not_to change(Post, :count)
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(json.fetch('errors')).to be_present
       end
     end
@@ -1579,7 +1620,7 @@ RSpec.describe 'Posts API', type: :request do
           )
         }.not_to change(Post, :count)
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(json.fetch('errors')).to be_present
       end
     end
@@ -1598,7 +1639,7 @@ RSpec.describe 'Posts API', type: :request do
           )
         }.not_to change(PostImplication, :count)
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(json.fetch('errors')).to be_present
       end
     end
@@ -1729,7 +1770,7 @@ RSpec.describe 'Posts API', type: :request do
         tags: 'deprecated_update_tag'
       )
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
         'tags' => ['廃止済みタグは付与できません．']
       )
@@ -1748,7 +1789,7 @@ RSpec.describe 'Posts API', type: :request do
             title: 'updated title',
             tags: 'nico:nico_tag')
 
-        expect(response).to have_http_status(:unprocessable_entity), response.body
+        expect(response).to have_http_status(:unprocessable_content), response.body
         expect(json).to include(
             'type' => 'validation_error',
             'message' => '入力内容を確認してください．',
@@ -1855,7 +1896,7 @@ RSpec.describe 'Posts API', type: :request do
             title: 'updated title',
             tags: 'spec_tag' }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(json.fetch('errors')).to be_present
       end
     end
@@ -1881,7 +1922,7 @@ RSpec.describe 'Posts API', type: :request do
           parent_post_ids: 'abc'
         )
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(post_record.reload.parent_posts.pluck(:id)).to eq([parent_post.id])
       end
     end
@@ -1907,7 +1948,7 @@ RSpec.describe 'Posts API', type: :request do
           parent_post_ids: '999999999'
         )
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(post_record.reload.parent_posts.pluck(:id)).to eq([parent_post.id])
       end
     end
@@ -1923,7 +1964,7 @@ RSpec.describe 'Posts API', type: :request do
           parent_post_ids: post_record.id.to_s
         )
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
 
         expect(PostImplication.exists?(
           post_id: post_record.id,
@@ -2628,7 +2669,7 @@ RSpec.describe 'Posts API', type: :request do
             thumbnail: dummy_upload)
       end.not_to change(PostVersion, :count)
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
     end
 
     it 'does not create a version when PUT /posts/:id is invalid' do
@@ -2644,7 +2685,7 @@ RSpec.describe 'Posts API', type: :request do
             original_created_before: Time.zone.local(2020, 1, 1, 0, 0, 0).iso8601)
       end.not_to change(PostVersion, :count)
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
     end
 
     it 'rejects second-bearing original created timestamps on POST /posts' do
@@ -2657,7 +2698,7 @@ RSpec.describe 'Posts API', type: :request do
           thumbnail: dummy_upload,
           original_created_from: '2020-01-01T00:00:01Z')
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
         'original_created_from' => ['オリジナルの作成日時は分単位で入力してください．']
       )
@@ -2674,7 +2715,7 @@ RSpec.describe 'Posts API', type: :request do
           thumbnail: dummy_upload,
           original_created_before: '2020-01-01T00:00:00.123Z')
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
         'original_created_before' => ['オリジナルの作成日時は分単位で入力してください．']
       )
@@ -2692,7 +2733,7 @@ RSpec.describe 'Posts API', type: :request do
           original_created_from: '2020-01-01T00:00Z',
           original_created_before: '2020-01-01T00:00Z')
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
         'original_created_at' => ['オリジナルの作成日時の順番がをかしぃです．']
       )
@@ -2726,7 +2767,7 @@ RSpec.describe 'Posts API', type: :request do
           tags: 'spec_tag',
           original_created_from: 'not-a-time')
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
         'original_created_from' => ['オリジナルの作成日時の形式が不正です．']
       )

backend/spec/requests/tag_children_spec.rb

@@ -64,7 +64,7 @@ RSpec.describe "TagChildren", type: :request do
           do_request
         }.not_to change(TagImplication, :count)
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(TagImplication.where(tag: child, parent_tag: parent)).not_to exist
       end
     end

backend/spec/requests/tag_descriptions_spec.rb

@@ -303,7 +303,7 @@ RSpec.describe 'Tag description native API', type: :request do
       headers
       before_state = stored_state
       native_write(body: '')
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json).to include('type' => 'validation_error',
                              'errors' => include('body' => a_kind_of(Array)))
       expect(stored_state).to eq(before_state)

backend/spec/requests/tag_group_locale_spec.rb

@@ -84,7 +84,7 @@ RSpec.describe 'Tag group locale contracts', type: :request do
     put "/wiki/#{ group.id }", params: {
         locale: 'ain-Kana', title: 'タググループ:partial rename', body: '- japanese_member' },
         headers: headers
-    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response).to have_http_status(:unprocessable_content)
     expect(group_state).to eq(before_state)
   end
 
@@ -117,7 +117,7 @@ RSpec.describe 'Tag group locale contracts', type: :request do
     expect(representation.fetch('members').sole.fetch('tag').fetch('name')).to be_nil
     expect(representation.fetch('placements').sole.fetch('tag').fetch('name')).to be_nil
     get "/wiki/#{ old_group.id }", params: { locale: 'ain-Kana', version: version.id }
-    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response).to have_http_status(:unprocessable_content)
     expect(response.body).not_to include('historical_japanese', 'current_ainu')
   end
 end

backend/spec/requests/tag_group_markdown_spec.rb

@@ -133,7 +133,7 @@ RSpec.describe 'Tag group Markdown round trips through the Wiki facade', type: :
 
     get group_title_path('混在構造')
 
-    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response).to have_http_status(:unprocessable_content)
     expect(group_rows('tag_groups', id:).sole.fetch('id')).to eq(id)
   end
 
@@ -142,7 +142,7 @@ RSpec.describe 'Tag group Markdown round trips through the Wiki facade', type: :
 
     get group_title_path('未配置構造')
 
-    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response).to have_http_status(:unprocessable_content)
     expect(group_rows('tag_groups', id:).sole.fetch('id')).to eq(id)
   end
 end

backend/spec/requests/tag_group_wiki_write_spec.rb

@@ -21,7 +21,7 @@ RSpec.describe 'Tag group Wiki facade writes', type: :request do
     before_state = group_state
     yield
     aggregate_failures do
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(group_state).to eq(before_state)
       expect(response.media_type).to eq('application/json')
       expect(response.body).not_to be_empty

backend/spec/requests/tag_group_write_integrity_spec.rb

@@ -27,7 +27,7 @@ RSpec.describe 'Tag group write integrity', type: :request do
   def expect_no_writes
     before_state = group_state
     yield
-    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response).to have_http_status(:unprocessable_content)
     expect(group_state).to eq(before_state)
   end
 

backend/spec/requests/tag_groups_spec.rb

@@ -148,7 +148,7 @@ RSpec.describe 'Tag group native API', type: :request do
           before_state = group_state
           native_write(operation, payload.merge(invalid))
           aggregate_failures do
-            expect(response).to have_http_status(:unprocessable_entity)
+            expect(response).to have_http_status(:unprocessable_content)
             expect(group_state).to eq(before_state)
           end
         end
@@ -158,7 +158,7 @@ RSpec.describe 'Tag group native API', type: :request do
         before_state = group_state
         invalid = [{ tag_id: tag.id, section_name: '不正', children: [] }]
         native_write(operation, payload.merge(placements: invalid))
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(group_state).to eq(before_state)
       end
 
@@ -167,7 +167,7 @@ RSpec.describe 'Tag group native API', type: :request do
         before_state = group_state
         native_write(operation, payload.merge(
             members: [{ tag_id: missing }], placements: [{ tag_id: missing, children: [] }]))
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(group_state).to eq(before_state)
       end
 
@@ -177,7 +177,7 @@ RSpec.describe 'Tag group native API', type: :request do
         native_write(operation, payload.merge(
             members: [{ tag_group_id: missing }],
             placements: [{ tag_group_id: missing, children: [] }]))
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(group_state).to eq(before_state)
       end
 
@@ -186,7 +186,7 @@ RSpec.describe 'Tag group native API', type: :request do
         6.times { nodes = [{ tag_id: tag.id, children: nodes }] }
         before_state = group_state
         native_write(operation, payload.merge(placements: nodes))
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(group_state).to eq(before_state)
       end
     end
@@ -206,7 +206,7 @@ RSpec.describe 'Tag group native API', type: :request do
       before_state = group_state
       native_write(:update, payload.merge(
           members: [{ tag_group_id: parent }], placements: []))
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(group_state).to eq(before_state)
     end
 
@@ -214,7 +214,7 @@ RSpec.describe 'Tag group native API', type: :request do
       before_state = group_state
       native_write(:update, payload.merge(
           members: [{ tag_group_id: group_id }], placements: []))
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(group_state).to eq(before_state)
     end
 

backend/spec/requests/tags_deerjikists_spec.rb

@@ -297,7 +297,7 @@ RSpec.describe 'Tags deerjikists API', type: :request do
             do_request
           }.not_to change { Deerjikist.where(tag: tag).map { |d| [d.platform, d.code] } }
 
-          expect(response).to have_http_status(:unprocessable_entity)
+          expect(response).to have_http_status(:unprocessable_content)
           expect(json).to include(
               'type' => 'validation_error',
               'message' => '入力内容を確認してください．',
@@ -321,7 +321,7 @@ RSpec.describe 'Tags deerjikists API', type: :request do
             do_request
           }.not_to change { Deerjikist.where(tag: tag).map { |d| [d.platform, d.code] } }
 
-          expect(response).to have_http_status(:unprocessable_entity)
+          expect(response).to have_http_status(:unprocessable_content)
           expect(json.fetch('errors')).to include(
             'deerjikists.0.platform' => [be_present],
           )
@@ -352,7 +352,7 @@ RSpec.describe 'Tags deerjikists API', type: :request do
             do_request
           }.not_to change { Deerjikist.order(:platform, :code).pluck(:platform, :code, :tag_id) }
 
-          expect(response).to have_http_status(:unprocessable_entity)
+          expect(response).to have_http_status(:unprocessable_content)
           expect(json.fetch('errors')).to include(
             'deerjikists.1.code' => [include('existing-deerjikist')],
           )

backend/spec/requests/tags_spec.rb

@@ -696,7 +696,7 @@ RSpec.describe 'Tags API', type: :request do
       it 'nico category への変更は 422 を返す' do
         patch "/tags/#{tag.id}", params: { name: 'new', category: 'nico' }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(primary_tag_name_for(tag.reload, 'ja').name).to eq('spec_tag')
         expect(tag.category).to eq('general')
       end
@@ -740,7 +740,7 @@ RSpec.describe 'Tags API', type: :request do
           patch "/tags/#{tag.id}", params: { category: 'nico' }
         }.not_to change(TagVersion, :count)
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(tag.reload.category).to eq('general')
       end
 
@@ -824,7 +824,7 @@ RSpec.describe 'Tags API', type: :request do
 
         patch "/tags/#{ tag.id }", params: { name: 'unknown' }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(json.fetch('errors')).to include(
           'name' => ['その名前は既に使はれてゐます．']
         )
@@ -840,7 +840,7 @@ RSpec.describe 'Tags API', type: :request do
 
         patch "/tags/#{ system_tag.id }", params: { name: 'patch_system_tag_renamed' }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(primary_tag_name_for(system_tag.reload, 'ja').name).to eq('bot操作')
       end
     end
@@ -1144,7 +1144,7 @@ RSpec.describe 'Tags API', type: :request do
           parent_tags: '',
         }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(primary_tag_name_for(tag.reload, 'ja').name).to eq('spec_tag')
       end
 
@@ -1156,7 +1156,7 @@ RSpec.describe 'Tags API', type: :request do
           parent_tags: '',
         }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(primary_tag_name_for(tag.reload, 'ja').name).to eq('spec_tag')
         expect(tag.category).to eq('general')
       end
@@ -1169,7 +1169,7 @@ RSpec.describe 'Tags API', type: :request do
           parent_tags: '',
         }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(json.fetch('errors')).to include(
           'deprecated' => ['廃止状態は必須です．']
         )
@@ -1366,7 +1366,7 @@ RSpec.describe 'Tags API', type: :request do
           }
         }.not_to change(TagVersion, :count)
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
 
         expect(primary_tag_name_for(tag.reload, 'ja').name).to eq('spec_tag')
         expect(tag.category).to eq('general')
@@ -1387,7 +1387,7 @@ RSpec.describe 'Tags API', type: :request do
           }
         }.not_to change(TagVersion, :count)
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
 
         expect(primary_tag_name_for(system_tag.reload, 'ja').name).to eq(old_name)
         expect(system_tag.category).to eq(old_category)
@@ -1569,7 +1569,7 @@ RSpec.describe 'Tags API', type: :request do
           deprecated: '0',
         }
 
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
 
         expect(TagImplication.where(tag:, parent_tag: child)).not_to exist
       end

backend/spec/requests/theatre_comments_spec.rb

@@ -131,7 +131,7 @@ RSpec.describe 'TheatreComments', type: :request do
         post "/theatres/#{theatre.id}/comments", params: { content: '   ' }
       }.not_to change(TheatreComment, :count)
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
     end
 
     it 'theatre が存在しなければ 404 を返す' do

backend/spec/requests/theatres_spec.rb

@@ -376,7 +376,7 @@ RSpec.describe 'Theatres API', type: :request do
         put "/theatres/#{theatre.id}/skip_vote", params: { post_id: 'invalid' }
       }.not_to change(TheatreSkipVote, :count)
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
     end
 
     it 'records a vote and returns the current vote status before majority' do

backend/spec/requests/user_settings_spec.rb

@@ -79,7 +79,7 @@ RSpec.describe 'user settings', type: :request do
 
       patch '/users/settings', params: { theme: 1 }, as: :json
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json).to include('type' => 'validation_error')
       expect(json.fetch('errors')).to include(
           'theme' => ['値の型が不正です．'])
@@ -90,7 +90,7 @@ RSpec.describe 'user settings', type: :request do
 
       patch '/users/settings', params: { theme: 'neon' }, as: :json
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json).to include('type' => 'validation_error')
       expect(json.fetch('errors').fetch('theme')).to be_present
     end

backend/spec/requests/user_theme_slots_spec.rb

@@ -84,7 +84,7 @@ RSpec.describe 'user theme slots', type: :request do
           params: { tokens: 'not-object' },
           as: :json
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
           'base_theme' => ['値が不正です．'])
     end
@@ -96,7 +96,7 @@ RSpec.describe 'user theme slots', type: :request do
           params: { tokens: 'not-object' },
           as: :json
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
           'tokens' => ['JSON object で指定してください．'])
     end

backend/spec/requests/users_spec.rb

@@ -119,7 +119,7 @@ RSpec.describe 'Users', type: :request do
           params: { name: '   ' },
           headers: auth_headers(user)
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(json.fetch('errors')).to include(
           'name' => ['名前は必須です．'])
     end

backend/spec/requests/wiki_creation_freeze_spec.rb

@@ -39,7 +39,7 @@ RSpec.describe 'Wiki creation freeze', type: :request do
       it "rejects invalid description body #{ body.inspect } atomically" do
         before_state = group_state
         put "/wiki/#{ page.id }", params: { title: tag.name('ja'), body: }, headers: headers
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
         expect(group_state).to eq(before_state)
       end
     end

backend/spec/requests/wiki_spec.rb

@@ -100,12 +100,12 @@ RSpec.describe 'Wiki API', type: :request do
     context 'when params invalid' do
       it 'returns 422 when title blank' do
         post endpoint, params: { title: '', body: 'Hello' }, headers: auth_headers(member)
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
       end
 
       it 'returns 422 when body blank' do
         post endpoint, params: { title: 'Test', body: '' }, headers: auth_headers(member)
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
       end
     end
 
@@ -160,7 +160,7 @@ RSpec.describe 'Wiki API', type: :request do
         put "/wiki/#{page.id}",
             params: { title: 'TestPage', body: '' },
             headers: auth_headers(member)
-        expect(response).to have_http_status(:unprocessable_entity)
+        expect(response).to have_http_status(:unprocessable_content)
       end
     end
 

backend/spec/requests/wiki_title_collision_spec.rb

@@ -34,7 +34,7 @@ RSpec.describe 'Wiki title collision', type: :request do
         },
         headers: auth_headers(user)
 
-    expect(response).to have_http_status(:unprocessable_entity)
+    expect(response).to have_http_status(:unprocessable_content)
 
     source.reload
 

backend/spec/requests/wiki_unmigrated_contract_spec.rb

@@ -18,7 +18,7 @@ RSpec.describe 'Removed standalone Wiki resources', type: :request do
       before_state = group_state
       post '/wiki', params: { title:, body: 'body' },
            headers: cookie_headers(user)
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:unprocessable_content)
       expect(group_state).to eq(before_state)
     end
   end

backend/spec/services/counts_export_spec.rb

@@ -221,9 +221,15 @@ RSpec.describe CountsExportDownload::ResponseBody do
       body = described_class.new(source) { |state| states << state; true }
       response = ActionDispatch::Response.new
       response.body = body
-      deferred = response.stream.to_ary
+
+      _, _, rack_body = response.to_a
+
       expect(states).to eq([])
-      expect(deferred.to_a.join).to eq(payload)
+
+      chunks = []
+      rack_body.each { |chunk| chunks << chunk }
+
+      expect(chunks.join).to eq(payload)
       expect(states.count('started')).to eq(1)
     end
   end

backend/spec/services/counts_pivot_security_spec.rb

@@ -69,27 +69,29 @@ RSpec.describe 'Counts masked pivot contracts' do
     end
   end
 
-  it 'preserves five tag occurrences after merging private tags and across pages' do
+  it 'counts one opaque collection per private version across pages' do
     [nil, guest, member, admin].each do |user|
       page = result(user)
-      expect(grand(page)).to eq(5)
-      expect(page[:cells].sum { _1[:count] }).to eq(5)
+      expected = user == admin ? 5 : 6
+      expect(grand(page)).to eq(expected)
+      expect(page[:cells].sum { _1[:count] }).to eq(expected)
       expect(page).not_to have_key(:excluded_count)
       paged = result(user, 'limit' => '1')
-      expect(grand(paged)).to eq(5)
+      expect(grand(paged)).to eq(expected)
       expect(result(user, 'limit' => '1', 'page' => '2')[:group_count])
           .to eq(page[:group_count])
     end
     public_page = result(nil)
     hidden = public_page[:cells].select { _1[:values].first == CountsAxes::MASKED_VALUE }
-    expect(hidden.sum { _1[:count] }).to eq(3)
+    expect(hidden.sum { _1[:count] }).to eq(4)
     expect(public_page[:axis_labels]['a0']).not_to have_key("internal:#{ tags.first.id }")
     expect(public_page.to_json).not_to include('hidden-title', 'private-discard')
   end
 
   it 'retains distinct membership when tags are not a row axis' do
     [nil, admin].each do |user|
-      expect(grand(result(user, 'rows' => 'event_type', 'cols' => 'tags'))).to eq(3)
+      expect(grand(result(user, 'rows' => 'event_type', 'cols' => 'tags')))
+          .to eq(user == admin ? 3 : 5)
       expect(result(user, 'rows' => '', 'cols' => '')[:cells].sole[:count]).to eq(5)
       details = result(user, 'mode' => 'details', 'rows' => '', 'cols' => '')
       expect(details[:count]).to eq(user == admin ? 5 : 1)
@@ -121,14 +123,13 @@ RSpec.describe 'Counts masked pivot contracts' do
   it 'counts distinct changed records when tags are not additive row tuples' do
     [nil, admin].each do |user|
       page = result(user, 'rows' => 'changed_field', 'cols' => 'event_type')
-      expect(grand(page)).to eq(2)
+      expect(grand(page)).to eq(user == admin ? 2 : 4)
       if user.nil?
         expect(page[:cells].map { _1[:values].first }.uniq).to eq([CountsAxes::MASKED_VALUE])
       end
-      # Changed discard snapshots have no tags: no full cell contributes here.
-      empty = result(user, 'rows' => 'changed_field', 'cols' => 'tags')
-      expect(empty[:cells]).to be_empty
-      expect(grand(empty)).to eq(0)
+      # Private empty collections contribute the same opaque tuple as populated ones.
+      combined = result(user, 'rows' => 'changed_field', 'cols' => 'tags')
+      expect(grand(combined)).to eq(user == admin ? 0 : 4)
     end
   end
 
@@ -142,7 +143,7 @@ RSpec.describe 'Counts masked pivot contracts' do
     expect(page[:row_headers]).to include(hash_including(values: [nil], kind: 'data'))
   end
 
-  it 'sorts public numeric values numerically alongside a masked group' do
+  it 'sorts public version numbers numerically including formerly hidden records' do
     post = PostVersion.order(:id).last.post
     [2, 10].each do |number|
       PostVersion.create!(post:, version_no: number, event_type: 'update',
@@ -151,27 +152,196 @@ RSpec.describe 'Counts masked pivot contracts' do
     end
     page = result(nil, 'rows' => 'version_no', 'cols' => '')
     values = page[:row_headers].select { _1[:kind] == 'data' }.map { _1[:values].first }
-    expect(values.reject { _1 == CountsAxes::MASKED_VALUE }.map(&:to_i)).to eq([1, 2, 10])
-    expect(values.last).to eq(CountsAxes::MASKED_VALUE)
+    expect(values.map(&:to_i)).to eq([1, 2, 10])
   end
 
-  it 'rejects private predicates and supplied measure coordinates before SQL labels escape' do
-    probes = [{ 'resource_id' => PostVersion.first.post_id.to_s },
-        { 'tags' => 'A' },
-        { 'conditions' => '', 'conditions.0.field' => 'title', 'conditions.0.operator' => 'eq',
-          'conditions.0.value' => 'hidden-title-0' },
-        { 'drill' => '', 'drill.0.field' => 'tags', 'drill.0.value_type' => 'string',
-          'drill.0.value' => "internal:#{ tags.first.id }" },
+  it 'keeps public identity predicates and excludes private attributes' do
+    hidden_id = PostVersion.first.post_id.to_s
+    base = { 'rows' => '', 'cols' => '' }
+    condition = lambda do |field, operator, value|
+      { 'conditions' => '', 'conditions.0.field' => field,
+        'conditions.0.operator' => operator, 'conditions.0.value' => value }
+    end
+
+    expect(result(nil, base.merge('resource_id' => hidden_id))[:cells].sole[:count]).to eq(2)
+    expect(result(nil, base.merge(condition.call('version_no', 'eq', '2')))[:cells]
+        .sole[:count]).to eq(2)
+    expect(result(nil, base.merge(condition.call('user', 'eq', member.id.to_s)))[:cells]
+        .sole[:count]).to eq(5)
+    expect(result(nil, base.merge(condition.call('title', 'eq', 'hidden-title-0')))[:cells]
+        .sole[:count]).to eq(0)
+    expect(result(nil, base.merge(condition.call('title', 'ne', 'hidden-title-0')))[:cells]
+        .sole[:count]).to eq(1)
+    expect(result(nil, base.merge(condition.call('title', 'eq', '********')))[:cells]
+        .sole[:count]).to eq(0)
+    expect(result(nil, base.merge(condition.call('video_ms', 'eq', '********')))[:cells]
+        .sole[:count]).to eq(0)
+    expect(result(nil, base.merge(condition.call('title', 'like', '%title%')))[:cells]
+        .sole[:count]).to eq(1)
+    expect(result(nil, base.merge(condition.call('title', 'like', '%')))[:cells]
+        .sole[:count]).to eq(1)
+    expect(result(nil, base.merge('tags' => 'C'))[:cells].sole[:count]).to eq(1)
+    expect(result(nil, base.merge('tags' => 'not:C'))[:cells].sole[:count]).to eq(0)
+  end
+
+  it 'retains public OR branches while rejecting private predicates on hidden rows' do
+    HistoryAccess.set(user: nil) do
+      population = CountsPopulation.new(params.merge('rows' => '', 'cols' => ''),
+          authorisation_flg: false)
+      condition = CountsCondition.new(population)
+      public_scope = condition.apply(population.scope,
+          { 'field' => 'event_type', 'operator' => 'eq', 'value' => 'discard' })
+      private_scope = condition.apply(population.scope,
+          { 'field' => 'title', 'operator' => 'ne', 'value' => 'unrelated' })
+      masked_scope = condition.apply(population.scope,
+          { 'field' => 'title', 'operator' => 'eq', 'value' => '********' })
+      expect(public_scope.except(:select).count).to eq(2)
+      expect(public_scope.or(private_scope).except(:select).count).to eq(3)
+      expect(private_scope.or(public_scope).except(:select).count).to eq(3)
+      expect(public_scope.or(masked_scope).except(:select).count).to eq(2)
+      expect(public_scope.merge(private_scope).except(:select).count).to eq(0)
+    end
+  end
+
+  it 'excludes private collections from positive, negative, AND and OR tag searches' do
+    settings = { 'rows' => '', 'cols' => '' }
+    { 'C' => 1, 'not:C' => 0, 'not:unknown' => 1, '********' => 0,
+      'not:********' => 1, 'not:C C' => 0, 'not:C type:or C' => 1 }.each do |value, count|
+      expect(result(nil, settings.merge('tags' => value))[:cells].sole[:count]).to eq(count)
+    end
+  end
+
+  it 'ignores empty numeric and interval bounds without restricting private history' do
+    settings = { 'rows' => '', 'cols' => '', 'conditions' => '' }
+    { 'video_ms' => ['eq', 'ne', 'gt', 'ge', 'lt', 'le', 'range'],
+      'tags.sections' => ['range'] }.each do |field, operators|
+      operators.each do |operator|
+        condition = settings.merge('conditions.0.field' => field,
+            'conditions.0.operator' => operator)
+        empty = condition.merge('conditions.0.value' => '')
+        expect(result(nil, condition)[:cells].sole[:count]).to eq(5)
+        expect(result(nil, empty)[:cells].sole[:count]).to eq(5)
+        expect(result(nil, empty.merge('conditions.0.blank' => '0'))[:cells]
+            .sole[:count]).to eq(5)
+        if operator == 'range'
+          empty['conditions.0.end'] = ''
+          expect(result(nil, empty)[:cells].sole[:count]).to eq(5)
+          ['conditions.0.value', 'conditions.0.end'].each do |key|
+            active = empty.merge(key => '100')
+            expect(result(nil, active)[:cells].sole[:count]).to eq(0)
+          end
+        end
+      end
+    end
+  end
+
+  it 'keeps typed marker sets active after incompatible marker values are removed' do
+    settings = { 'rows' => '', 'cols' => '', 'conditions' => '',
+                 'conditions.0.field' => 'video_ms', 'conditions.0.values' => '1',
+                 'condition_values' => '', 'condition_values.0.condition' => '0',
+                 'condition_values.0.value_type' => 'string',
+                 'condition_values.0.value' => '********' }
+    ['in', 'not_in'].each do |operator|
+      expected = operator == 'in' ? 0 : 1
+      condition = settings.merge('conditions.0.operator' => operator)
+      expect(result(nil, condition)[:cells].sole[:count]).to eq(expected)
+    end
+  end
+
+  it 'restricts active numeric comparisons and preserves empty selection semantics' do
+    settings = { 'rows' => '', 'cols' => '', 'conditions' => '',
+                 'conditions.0.field' => 'video_ms' }
+    ['eq', 'ne', 'gt', 'ge', 'lt', 'le', 'range'].each do |operator|
+      condition = settings.merge('conditions.0.operator' => operator,
+          'conditions.0.value' => '0')
+      condition['conditions.0.end'] = '100' if operator == 'range'
+      # The one public row is NULL; private NULLs and real values never match.
+      expected = operator == 'ne' ? 1 : 0
+      expect(result(nil, condition)[:cells].sole[:count]).to eq(expected)
+    end
+    ['in', 'not_in'].each do |operator|
+      condition = settings.merge('conditions.0.operator' => operator,
+          'conditions.0.values' => '1', 'condition_values' => '')
+      expected = operator == 'not_in' ? 5 : 0
+      expect(result(nil, condition)[:cells].sole[:count]).to eq(expected)
+    end
+    blank = settings.merge('conditions.0.operator' => 'eq', 'conditions.0.blank' => '1')
+    expect(result(nil, blank)[:cells].sole[:count]).to eq(1)
+  end
+
+  it 'preserves empty tag sets and restricts active blank collection predicates' do
+    settings = { 'rows' => '', 'cols' => '', 'conditions' => '',
+                 'conditions.0.field' => 'tags' }
+    ['any', 'all', 'none'].each do |operator|
+      condition = settings.merge('conditions.0.operator' => operator,
+          'conditions.0.values' => '1', 'condition_values' => '')
+      expected = operator == 'any' ? 0 : 5
+      expect(result(nil, condition)[:cells].sole[:count]).to eq(expected)
+    end
+    blank = settings.merge('conditions.0.operator' => 'eq', 'conditions.0.blank' => '1')
+    expect(result(nil, blank)[:cells].sole[:count]).to eq(0)
+  end
+
+  it 'rejects server-only coordinates in column order' do
+    probes = [
         { 'cols' => 'tags', 'column_order' => '', 'column_order.0.value_type' => 'string',
           'column_order.0.value' => CountsAxes::MASKED_VALUE }]
     HistoryAccess.set(user: nil) do
       probes.each do |probe|
-        expect { CountsTableQuery.new(params.merge(probe)) }
+        expect { CountsTableQuery.new(params.merge(probe)).call }
             .to raise_error(CountsAxes::PrivateCondition)
       end
     end
   end
 
+
+  it 'keeps private collection and change counts independent of stored elements' do
+    settings = [
+        { 'rows' => 'tags', 'cols' => 'changed_field' },
+        { 'rows' => 'changed_field tags', 'cols' => '' }]
+    original = settings.map { result(nil, _1) }
+    snapshot = tags.map do |tag|
+      { tag_id: tag.id, version_no: 1, sections: [] }
+    end
+    hidden_posts = PostVersion.where(event_type: 'discard').pluck(:post_id)
+    PostVersion.where(post_id: hidden_posts).update_all(
+        title: 'same hidden value', tags_json: snapshot)
+    expect(settings.map { result(nil, _1) }).to eq(original)
+  end
+
+  it 'excludes private tag and change coordinates from drill conditions' do
+    ['tags', 'changed_field'].each do |field|
+      settings = { 'rows' => field, 'cols' => '' }
+      page = result(nil, settings)
+      cell = page[:cells].find { _1[:values] == [CountsAxes::MASKED_VALUE] }
+      expect(cell[:count]).to eq(4)
+      [CountsAxes::MASKED_VALUE, CountsAxes::MASKED_TEXT].each do |value|
+        drill = { 'drill' => '', 'drill.0.field' => field,
+                  'drill.0.value_type' => 'string', 'drill.0.value' => value }
+        expect(result(nil, settings.merge(drill))[:cells]).to be_empty
+        details = result(nil, settings.merge(drill).merge('mode' => 'details'))
+        expect(details[:versions]).to be_empty
+        condition = { 'conditions' => '', 'conditions.0.field' => field,
+                      'conditions.0.operator' => 'axis_eq',
+                      'conditions.0.value_type' => 'string', 'conditions.0.value' => value }
+        expect(result(nil, settings.merge(condition))[:cells]).to be_empty
+      end
+    end
+  end
+
+  it 'rejects real private tag and change coordinates for non-admin users' do
+    [nil, guest, member].each do |user|
+      { 'tags' => "internal:#{ tags.first.id }", 'changed_field' => 'title' }.each do
+          |field, value|
+        settings = { 'rows' => '', 'cols' => '', 'drill' => '',
+                     'drill.0.field' => field, 'drill.0.value_type' => 'string',
+                     'drill.0.value' => value }
+        expect(result(user, settings)[:cells].sole[:count]).to eq(0)
+        expect(result(admin, settings)[:cells].sole[:count]).to be > 0
+      end
+    end
+  end
+
   it 'keeps public column sorting usable while guessed private coordinates match nothing' do
     first = result(nil, 'rows' => 'event_type', 'cols' => 'tags')
     probe = result(nil, 'rows' => 'event_type', 'cols' => 'tags',
@@ -187,7 +357,7 @@ RSpec.describe 'Counts masked pivot contracts' do
     HistoryAccess.set(user: nil) do
       payload = params.merge('format' => 'json')
       json = JSON.parse(CountsTableExport.new(payload).body.to_a.join)
-      expect(json['data'].sum { _1['kind'] == 'data' ? _1['count'] : 0 }).to eq(5)
+      expect(json['data'].sum { _1['kind'] == 'data' ? _1['count'] : 0 }).to eq(6)
       expect(json.to_json).not_to include('hidden-title', 'private-discard')
       csv = CountsTableExport.new(payload.merge('format' => 'csv')).body.to_a.join
       expect(csv).to include('********')

frontend/src/components/TagSearch.test.tsx

@@ -0,0 +1,120 @@
+import { fireEvent, screen } from '@testing-library/react'
+import userEvent from '@testing-library/user-event'
+import { useLocation } from 'react-router-dom'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import TagSearch from '@/components/TagSearch'
+import * as api from '@/lib/api'
+import { buildTag } from '@/test/factories'
+import { renderWithProviders } from '@/test/render'
+
+
+const LocationOutput = () => {
+  const location = useLocation ()
+  return <output data-testid="location">{location.pathname}{location.search}</output>
+}
+
+
+const renderSearch = () => renderWithProviders (
+    <>
+      <TagSearch/>
+      <LocationOutput/>
+    </>, { route: '/ja/posts?page=3' })
+
+
+describe ('TagSearch', () => {
+  beforeEach (() => {
+    vi.spyOn (api, 'apiGet').mockResolvedValue ([])
+  })
+
+  it ('searches through native submission without an Enter key event', () => {
+    renderSearch ()
+    const input = screen.getByRole<HTMLInputElement> ('textbox')
+    fireEvent.change (input, { target: { value: '虹夏 not:TEST type:or' } })
+
+    expect (input.form).toBeInstanceOf (HTMLFormElement)
+    fireEvent.submit (input.form!)
+
+    const query = new URLSearchParams ({ tags: '虹夏 not:test', match: 'any' })
+    expect (screen.getByTestId ('location')).toHaveTextContent (
+	`/ja/posts?${ query }`)
+    expect (input).toHaveValue ('虹夏 not:test type:or')
+  })
+
+  it ('requests a search action from the software keyboard', () => {
+    renderSearch ()
+
+    expect (screen.getByRole ('textbox')).toHaveAttribute ('enterkeyhint', 'search')
+  })
+
+  it ('searches through the form when Enter is pressed', async () => {
+    const user = userEvent.setup ()
+    renderSearch ()
+
+    await user.type (screen.getByRole ('textbox'), '虹夏{Enter}')
+
+    const query = new URLSearchParams ({ tags: '虹夏', match: 'all' })
+    expect (screen.getByTestId ('location')).toHaveTextContent (
+	`/ja/posts?${ query }`)
+  })
+
+  it.each ([
+      { label: 'composition flag', composing: true, keyCode: 13 },
+      { label: 'legacy IME code', composing: false, keyCode: 229 }]) (
+      'cancels confirmation Enter with $label', ({ composing, keyCode }) => {
+    renderSearch ()
+    const input = screen.getByRole ('textbox')
+    fireEvent.change (input, { target: { value: '虹夏' } })
+    const uncancelled = fireEvent.keyDown (input, {
+	key: 'Enter', isComposing: composing, keyCode })
+
+    expect (uncancelled).toBe (false)
+    expect (screen.getByTestId ('location')).toHaveTextContent ('/ja/posts?page=3')
+    expect (input).toHaveValue ('虹夏')
+  })
+
+  it ('cancels Enter throughout composition even without keyboard IME flags', () => {
+    renderSearch ()
+    const input = screen.getByRole ('textbox')
+    fireEvent.compositionStart (input)
+    fireEvent.change (input, { target: { value: '虹夏' } })
+    const uncancelled = fireEvent.keyDown (input, {
+	key: 'Enter', isComposing: false, keyCode: 13 })
+
+    expect (uncancelled).toBe (false)
+    expect (screen.getByTestId ('location')).toHaveTextContent ('/ja/posts?page=3')
+    expect (input).toHaveValue ('虹夏')
+  })
+
+  it ('blocks direct submission during composition and allows it after confirmation', () => {
+    renderSearch ()
+    const input = screen.getByRole<HTMLInputElement> ('textbox')
+    fireEvent.compositionStart (input)
+    fireEvent.change (input, { target: { value: '虹夏' } })
+    fireEvent.submit (input.form!)
+
+    expect (screen.getByTestId ('location')).toHaveTextContent ('/ja/posts?page=3')
+    expect (input).toHaveValue ('虹夏')
+
+    fireEvent.compositionEnd (input)
+    fireEvent.submit (input.form!)
+
+    const query = new URLSearchParams ({ tags: '虹夏', match: 'all' })
+    expect (screen.getByTestId ('location')).toHaveTextContent (
+	`/ja/posts?${ query }`)
+  })
+
+  it ('selects the active suggestion without submitting the form', async () => {
+    vi.mocked (api.apiGet).mockResolvedValue ([buildTag ({ name: '虹夏' })])
+    const user = userEvent.setup ()
+    renderSearch ()
+
+    await user.type (screen.getByRole ('textbox'), '虹')
+    await screen.findByText ('虹夏')
+    await user.keyboard ('{ArrowDown}{Enter}')
+
+    expect (screen.getByRole ('textbox')).toHaveValue ('虹夏 ')
+    expect (screen.getByTestId ('location')).toHaveTextContent ('/ja/posts?page=3')
+    expect (screen.queryByText ('虹夏')).not.toBeInTheDocument ()
+  })
+})

frontend/src/components/TagSearch.tsx

@@ -1,6 +1,6 @@
 // TODO: タグ入力系すべてに同様の処理あるため共通化する．
 
-import { useEffect, useState } from 'react'
+import { useEffect, useRef, useState } from 'react'
 import { useLocation } from 'react-router-dom'
 
 import { useLocale, useLocaleNavigate } from '@/lib/useLocale'
@@ -10,7 +10,7 @@ import { inputClass } from '@/lib/utils'
 
 import TagSearchBox from './TagSearchBox'
 
-import type { ChangeEvent, FC, KeyboardEvent } from 'react'
+import type { ChangeEvent, FC, FormEvent, KeyboardEvent } from 'react'
 
 import type { Tag } from '@/types'
 
@@ -20,6 +20,7 @@ const TagSearch: FC = () => {
   const locale = useLocale ()
   const location = useLocation ()
   const navigate = useLocaleNavigate ()
+  const compositionFlgRef = useRef (false)
 
   const [activeIndex, setActiveIndex] = useState (-1)
   const [search, setSearch] = useState ('')
@@ -74,7 +75,34 @@ const TagSearch: FC = () => {
     setSuggestionsVsbl (false)
   }, [locale])
 
+  const handleSubmit = (ev: FormEvent<HTMLFormElement>) => {
+    ev.preventDefault ()
+    if (compositionFlgRef.current)
+      return
+
+    const parts = search.split (' ')
+    const match =
+	parts.map (t => t.toLowerCase ()).includes ('type:or') ? 'any' : 'all'
+    navigate (`/posts?${
+	(new URLSearchParams ({
+	    tags: parts.map (t => t.toLowerCase ())
+		       .filter (t => t !== 'type:or')
+		       .join (' '),
+	    match })).toString () }`)
+    setSuggestionsVsbl (false)
+    setRequest ({ query: '' })
+  }
+
   const handleKeyDown = (ev: KeyboardEvent<HTMLInputElement>) => {
+    if (compositionFlgRef.current
+	|| ev.nativeEvent.isComposing
+	|| ev.nativeEvent.keyCode === 229)
+    {
+      if (ev.key === 'Enter')
+	ev.preventDefault ()
+      return
+    }
+
     switch (ev.key)
     {
     case 'ArrowDown':
@@ -90,13 +118,12 @@ const TagSearch: FC = () => {
       break
 
     case 'Enter':
-      if (activeIndex < 0)
-	break
-      ev.preventDefault ()
       {
-	const selected = suggestions[activeIndex]
-	if (selected)
-	  handleTagSelect (selected)
+	const selected = suggestionsVsbl ? suggestions[activeIndex] : null
+	if (selected == null)
+	  break
+	ev.preventDefault ()
+	handleTagSelect (selected)
       }
       break
 
@@ -105,20 +132,6 @@ const TagSearch: FC = () => {
       setSuggestionsVsbl (false)
       break
     }
-    if (ev.key === 'Enter' && (!(suggestionsVsbl) || activeIndex < 0))
-      {
-	const parts = search.split (' ')
-	const match = parts.map (t => t.toLowerCase ()).includes ('type:or') ? 'any' : 'all'
-	navigate (`/posts?${
-	    (new URLSearchParams ({
-		tags: parts.map (t => t.toLowerCase ())
-			   .filter (t => t !== 'type:or')
-			   .join (' '),
-		match }))
-	    .toString () }`)
-	setSuggestionsVsbl (false)
-	setRequest ({ query: '' })
-      }
   }
 
   const handleTagSelect = (tag: Tag) => {
@@ -144,8 +157,9 @@ const TagSearch: FC = () => {
   }, [location.search])
 
   return (
-      <div className="relative w-full">
+      <form onSubmit={handleSubmit} className="relative w-full">
 	<input type="text"
+	       enterKeyHint="search"
 	       data-shortcut-focus-search="true"
 	       placeholder={message ('labels.tagSearch').text}
 	       value={search}
@@ -153,12 +167,18 @@ const TagSearch: FC = () => {
 	       onFocus={() => setSuggestionsVsbl (true)}
 	       onBlur={() => setSuggestionsVsbl (false)}
 	       onKeyDown={handleKeyDown}
+	       onCompositionStart={() => {
+		 compositionFlgRef.current = true
+	       }}
+	       onCompositionEnd={() => {
+		 compositionFlgRef.current = false
+	       }}
 	       className={inputClass (false,
 				      'px-3 py-2 dark:border-gray-600 dark:bg-gray-800 dark:text-white')}/>
 	<TagSearchBox suggestions={suggestionsVsbl && suggestions.length ? suggestions : [] as Tag[]}
 		      activeIndex={activeIndex}
 		      onSelect={handleTagSelect}/>
-      </div>)
+      </form>)
 }
 
 export default TagSearch

frontend/src/components/layout/SidebarComponent.test.tsx

@@ -70,6 +70,16 @@ describe ('SidebarComponent', () => {
     vi.spyOn (HTMLElement.prototype, 'hasPointerCapture').mockReturnValue (true)
   })
 
+  it ('limits sidebar scrolling to desktop to avoid clipping mobile suggestions', () => {
+    renderSidebar ()
+
+    // jsdom has no layout; guard the responsive classes responsible for clipping.
+    const sidebar = screen.getByText ('Sidebar body')
+
+    expect (sidebar).not.toHaveClass ('overflow-y-auto')
+    expect (sidebar).toHaveClass ('md:overflow-y-auto')
+  })
+
   it ('uses maxWidth without applying the container main-width reserve twice', async () => {
     localStorage.setItem ('sidebar:test-sidebar:left:width', '700')
     const onWidthChange = vi.fn ()

frontend/src/components/layout/SidebarComponent.tsx

@@ -339,7 +339,7 @@ const SidebarComponent: FC<Props> = ({
 	  </style>
 	</Helmet>
 
-	<div className="h-full overflow-y-auto p-4 sidebar">
+	<div className="h-full md:overflow-y-auto p-4 sidebar">
 	  {children}
 	</div>
 

frontend/src/pages/tags/TagDetailPage.test.tsx

@@ -35,6 +35,10 @@ const renderPage = () =>
 describe ('TagDetailPage', () => {
   beforeEach (() => {
     vi.clearAllMocks ()
+    tagsApi.fetchTag.mockReset ()
+    api.apiPut.mockReset ()
+    api.isApiError.mockReset ()
+    toastApi.toast.mockReset ()
     api.isApiError.mockReturnValue (false)
   })
 
@@ -51,8 +55,11 @@ describe ('TagDetailPage', () => {
   })
 
   it ('submits edited tag fields', async () => {
-    tagsApi.fetchTag.mockResolvedValueOnce (buildTag ({ id: 7, name: 'old' }))
-    api.apiPut.mockResolvedValueOnce (buildTag ({ id: 7, name: 'new', aliases: ['alias'] }))
+    const updatedTag = buildTag ({ id: 7, name: 'new', aliases: ['alias'] })
+    tagsApi.fetchTag
+	.mockResolvedValue (updatedTag)
+	.mockResolvedValueOnce (buildTag ({ id: 7, name: 'old' }))
+    api.apiPut.mockResolvedValueOnce (updatedTag)
 
     renderPage ()