#414

backend/Gemfile

@@ -71,5 +71,3 @@ 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 (8.0.5.1)
-      actionpack (= 8.0.5.1)
-      activesupport (= 8.0.5.1)
+    actioncable (8.0.2)
+      actionpack (= 8.0.2)
+      activesupport (= 8.0.2)
       nio4r (~> 2.0)
       websocket-driver (>= 0.6.1)
       zeitwerk (~> 2.6)
-    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)
+    actionmailbox (8.0.2)
+      actionpack (= 8.0.2)
+      activejob (= 8.0.2)
+      activerecord (= 8.0.2)
+      activestorage (= 8.0.2)
+      activesupport (= 8.0.2)
       mail (>= 2.8.0)
-    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)
+    actionmailer (8.0.2)
+      actionpack (= 8.0.2)
+      actionview (= 8.0.2)
+      activejob (= 8.0.2)
+      activesupport (= 8.0.2)
       mail (>= 2.8.0)
       rails-dom-testing (~> 2.2)
-    actionpack (8.0.5.1)
-      actionview (= 8.0.5.1)
-      activesupport (= 8.0.5.1)
+    actionpack (8.0.2)
+      actionview (= 8.0.2)
+      activesupport (= 8.0.2)
       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 (8.0.5.1)
-      actionpack (= 8.0.5.1)
-      activerecord (= 8.0.5.1)
-      activestorage (= 8.0.5.1)
-      activesupport (= 8.0.5.1)
+    actiontext (8.0.2)
+      actionpack (= 8.0.2)
+      activerecord (= 8.0.2)
+      activestorage (= 8.0.2)
+      activesupport (= 8.0.2)
       globalid (>= 0.6.0)
       nokogiri (>= 1.8.5)
-    actionview (8.0.5.1)
-      activesupport (= 8.0.5.1)
+    actionview (8.0.2)
+      activesupport (= 8.0.2)
       builder (~> 3.1)
       erubi (~> 1.11)
       rails-dom-testing (~> 2.2)
       rails-html-sanitizer (~> 1.6)
-    activejob (8.0.5.1)
-      activesupport (= 8.0.5.1)
+    activejob (8.0.2)
+      activesupport (= 8.0.2)
       globalid (>= 0.3.6)
-    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)
+    activemodel (8.0.2)
+      activesupport (= 8.0.2)
+    activerecord (8.0.2)
+      activemodel (= 8.0.2)
+      activesupport (= 8.0.2)
       timeout (>= 0.4.0)
-    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)
+    activestorage (8.0.2)
+      actionpack (= 8.0.2)
+      activejob (= 8.0.2)
+      activerecord (= 8.0.2)
+      activesupport (= 8.0.2)
       marcel (~> 1.0)
-    activesupport (8.0.5.1)
+    activesupport (8.0.2)
       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 (0.3.0)
+    base64 (0.2.0)
     bcrypt_pbkdf (1.1.1)
     bcrypt_pbkdf (1.1.1-arm64-darwin)
     bcrypt_pbkdf (1.1.1-x86_64-darwin)
-    benchmark (0.5.0)
-    bigdecimal (4.1.3)
+    benchmark (0.4.0)
+    bigdecimal (3.1.9)
     bootsnap (1.18.6)
       msgpack (~> 1.2)
     brakeman (7.0.2)
       racc
     builder (3.3.0)
     chronic (0.10.2)
-    concurrent-ruby (1.3.8)
-    connection_pool (3.0.2)
-    crass (1.0.7)
-    date (3.6.0)
+    concurrent-ruby (1.3.5)
+    connection_pool (2.5.3)
+    crass (1.0.6)
+    date (3.4.1)
     diff-lcs (1.6.2)
     discard (1.4.0)
       activerecord (>= 4.2, < 9.0)
@@ -115,9 +115,8 @@ GEM
     dotenv-rails (3.1.8)
       dotenv (= 3.1.8)
       railties (>= 6.1)
-    drb (2.2.3)
+    drb (2.2.1)
     ed25519 (1.4.0)
-    erb (6.0.7)
     erubi (1.13.1)
     factory_bot (6.5.6)
       activesupport (>= 6.1.0)
@@ -135,7 +134,7 @@ GEM
     gemojione (4.3.3)
       json
     github-markup (4.0.2)
-    globalid (1.4.0)
+    globalid (1.2.1)
       activesupport (>= 6.1)
     gollum (6.1.0)
       gemojione (~> 4.1)
@@ -167,20 +166,19 @@ GEM
     gollum-rugged_adapter (3.0)
       mime-types (~> 3.4)
       rugged (~> 1.5)
-    i18n (1.15.2)
+    i18n (1.14.7)
       concurrent-ruby (~> 1.0)
     image_processing (1.14.0)
       mini_magick (>= 4.9.5, < 6)
       ruby-vips (>= 2.0.17, < 3)
-    io-console (0.9.4)
-    irb (1.18.0)
+    io-console (0.8.0)
+    irb (1.15.2)
       pp (>= 0.6.0)
-      prism (>= 1.3.0)
       rdoc (>= 4.0.0)
       reline (>= 0.4.2)
     jmespath (1.6.2)
-    json (2.19.9)
-    jwt (3.3.0)
+    json (2.12.0)
+    jwt (2.10.1)
       base64
     kamal (2.6.1)
       activesupport (>= 7.0)
@@ -200,16 +198,15 @@ GEM
     language_server-protocol (3.17.0.5)
     lint_roller (1.1.0)
     logger (1.7.0)
-    loofah (2.25.2)
+    loofah (2.24.1)
       crass (~> 1.0.2)
       nokogiri (>= 1.12.0)
-    mail (2.9.1)
-      logger
+    mail (2.8.1)
       mini_mime (>= 0.1.1)
       net-imap
       net-pop
       net-smtp
-    marcel (1.2.1)
+    marcel (1.0.4)
     mime-types (3.7.0)
       logger
       mime-types-data (~> 3.2025, >= 3.2025.0507)
@@ -218,46 +215,45 @@ GEM
       benchmark
       logger
     mini_mime (1.1.5)
-    minitest (6.0.6)
-      drb (~> 2.0)
-      prism (~> 1.5)
-    msgpack (1.8.5)
-    multi_json (1.21.2)
+    minitest (5.25.5)
+    msgpack (1.8.0)
+    multi_json (1.15.0)
     mustache (1.1.1)
     mustache-sinatra (2.0.0)
       mustache (~> 1.0)
-    mustermann (3.1.1)
+    mustermann (3.0.3)
+      ruby2_keywords (~> 0.0.1)
     mysql2 (0.5.6)
-    net-imap (0.6.8)
+    net-imap (0.5.8)
       date
       net-protocol
     net-pop (0.1.2)
       net-protocol
-    net-protocol (0.4.0)
+    net-protocol (0.2.2)
       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 (0.5.2)
+    net-smtp (0.5.1)
       net-protocol
     net-ssh (7.3.0)
-    nio4r (2.7.5)
-    nokogiri (1.19.4-aarch64-linux-gnu)
+    nio4r (2.7.4)
+    nokogiri (1.18.8-aarch64-linux-gnu)
       racc (~> 1.4)
-    nokogiri (1.19.4-aarch64-linux-musl)
+    nokogiri (1.18.8-aarch64-linux-musl)
       racc (~> 1.4)
-    nokogiri (1.19.4-arm-linux-gnu)
+    nokogiri (1.18.8-arm-linux-gnu)
       racc (~> 1.4)
-    nokogiri (1.19.4-arm-linux-musl)
+    nokogiri (1.18.8-arm-linux-musl)
       racc (~> 1.4)
-    nokogiri (1.19.4-arm64-darwin)
+    nokogiri (1.18.8-arm64-darwin)
       racc (~> 1.4)
-    nokogiri (1.19.4-x86_64-darwin)
+    nokogiri (1.18.8-x86_64-darwin)
       racc (~> 1.4)
-    nokogiri (1.19.4-x86_64-linux-gnu)
+    nokogiri (1.18.8-x86_64-linux-gnu)
       racc (~> 1.4)
-    nokogiri (1.19.4-x86_64-linux-musl)
+    nokogiri (1.18.8-x86_64-linux-musl)
       racc (~> 1.4)
     octicons (19.15.2)
     ostruct (0.6.1)
@@ -265,73 +261,70 @@ GEM
     parser (3.3.8.0)
       ast (~> 2.4.1)
       racc
-    pp (0.6.4)
+    pp (0.6.2)
       prettyprint
-    prettyprint (0.2.1)
-    prism (1.9.0)
-    psych (5.5.0)
+    prettyprint (0.2.0)
+    prism (1.4.0)
+    psych (5.2.6)
       date
       stringio
     puma (6.6.0)
       nio4r (~> 2.0)
     racc (1.8.1)
-    rack (3.2.7)
+    rack (3.1.14)
     rack-cors (2.0.2)
       rack (>= 2.0.0)
-    rack-protection (4.2.1)
+    rack-protection (4.1.1)
       base64 (>= 0.1.0)
       logger (>= 1.6.0)
       rack (>= 3.0.0, < 4)
-    rack-session (2.1.2)
+    rack-session (2.1.1)
       base64 (>= 0.1.0)
       rack (>= 3.0.0)
-    rack-test (2.3.0)
+    rack-test (2.2.0)
       rack (>= 1.3)
-    rackup (2.3.1)
+    rackup (2.2.1)
       rack (>= 3)
-    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)
+    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)
       bundler (>= 1.15.0)
-      railties (= 8.0.5.1)
-    rails-dom-testing (2.3.0)
+      railties (= 8.0.2)
+    rails-dom-testing (2.2.0)
       activesupport (>= 5.0.0)
       minitest
       nokogiri (>= 1.6)
-    rails-html-sanitizer (1.7.1)
-      loofah (~> 2.25, >= 2.25.2)
+    rails-html-sanitizer (1.6.2)
+      loofah (~> 2.21)
       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 (8.0.5.1)
-      actionpack (= 8.0.5.1)
-      activesupport (= 8.0.5.1)
+    railties (8.0.2)
+      actionpack (= 8.0.2)
+      activesupport (= 8.0.2)
       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 (13.4.2)
-    rdoc (6.17.0)
-      erb
+    rake (13.2.1)
+    rdoc (6.13.1)
       psych (>= 4.0.0)
-      tsort
-    regexp_parser (2.13.1)
-    reline (0.7.0)
+    regexp_parser (2.10.0)
+    reline (0.6.1)
       io-console (~> 0.5)
-    rexml (3.4.4)
+    rexml (3.4.1)
     rouge (3.30.0)
     rspec-core (3.13.6)
       rspec-support (~> 3.13.0)
@@ -352,20 +345,20 @@ GEM
     rspec-support (3.13.6)
     rss (0.3.1)
       rexml
-    rubocop (1.92.0)
-      json (>= 2.3)
+    rubocop (1.75.6)
+      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 (>= 2.11.3, < 3.0)
-      rubocop-ast (>= 1.49.0, < 2.0)
+      regexp_parser (>= 2.9.3, < 3.0)
+      rubocop-ast (>= 1.44.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 2.4.0, < 4.0)
-    rubocop-ast (1.50.0)
+    rubocop-ast (1.44.1)
       parser (>= 3.3.7.2)
-      prism (~> 1.7)
+      prism (~> 1.4)
     rubocop-performance (1.25.0)
       lint_roller (~> 1.1)
       rubocop (>= 1.75.0, < 2.0)
@@ -384,23 +377,24 @@ GEM
     ruby-vips (2.2.3)
       ffi (~> 1.12)
       logger
+    ruby2_keywords (0.0.5)
     rugged (1.9.0)
     securerandom (0.4.1)
-    sinatra (4.2.1)
+    sinatra (4.1.1)
       logger (>= 1.6.0)
       mustermann (~> 3.0)
       rack (>= 3.0.0, < 4)
-      rack-protection (= 4.2.1)
+      rack-protection (= 4.1.1)
       rack-session (>= 2.0.0, < 3)
       tilt (~> 2.0)
-    sinatra-contrib (4.2.1)
+    sinatra-contrib (4.1.1)
       multi_json (>= 0.0.2)
       mustermann (~> 3.0)
-      rack-protection (= 4.2.1)
-      sinatra (= 4.2.1)
+      rack-protection (= 4.1.1)
+      sinatra (= 4.1.1)
       tilt (~> 2.0)
-    sprockets (4.4.1)
-      concurrent-ruby (~> 1.1)
+    sprockets (4.2.2)
+      concurrent-ruby (~> 1.0)
       logger
       rack (>= 2.2.4, < 4)
     sprockets-helpers (1.4.0)
@@ -409,14 +403,14 @@ GEM
       actionpack (>= 6.1)
       activesupport (>= 6.1)
       sprockets (>= 3.0.0)
-    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)
+    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)
     sshkit (1.24.0)
       base64
       logger
@@ -424,19 +418,18 @@ GEM
       net-sftp (>= 2.1.2)
       net-ssh (>= 2.8.0)
       ostruct
-    stringio (3.2.0)
+    stringio (3.1.7)
     therubyrhino (2.1.2)
       therubyrhino_jar (>= 1.7.4, < 1.7.9)
     therubyrhino_jar (1.7.8)
-    thor (1.5.0)
+    thor (1.3.2)
     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 (2.9.0)
-    timeout (0.6.1)
-    tsort (0.2.0)
+    tilt (2.6.0)
+    timeout (0.4.3)
     twitter-text (1.14.7)
       unf (~> 0.1.0)
     tzinfo (2.0.6)
@@ -447,16 +440,16 @@ GEM
     unicode-display_width (3.1.4)
       unicode-emoji (~> 4.0, >= 4.0.4)
     unicode-emoji (4.0.4)
-    uri (1.1.2)
+    uri (1.0.3)
     useragent (0.16.11)
     webrick (1.9.1)
-    websocket-driver (0.8.2)
+    websocket-driver (0.7.7)
       base64
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
     whenever (1.0.0)
       chronic (>= 0.6.3)
-    zeitwerk (2.8.3)
+    zeitwerk (2.7.2)
 
 PLATFORMS
   aarch64-linux
@@ -480,7 +473,6 @@ DEPENDENCIES
   factory_bot_rails
   gollum
   image_processing (~> 1.14)
-  json (~> 2.19.9)
   jwt
   kamal
   mysql2 (~> 0.5.6)

backend/app/controllers/post_versions_controller.rb

@@ -14,9 +14,8 @@ class PostVersionsController < ApplicationController
 
     offset = (page - 1) * limit
 
-    q = HistoryAccess.visible(PostVersion.all)
+    q = HistoryAccess.visible(version_scope)
     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 })) " +
@@ -29,12 +28,9 @@ class PostVersionsController < ApplicationController
 
     count = q.except(:select, :order, :limit, :offset).count
 
-    ids = q.order(Arel.sql('post_versions.created_at DESC, post_versions.id DESC'))
+    versions = 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

@@ -37,10 +37,20 @@ class PostsController < ApplicationController
 
     offset = (page - 1) * limit
 
-    needs_history_join = order[0] == 'updated_at' || updated_between.any?(&:present?)
+    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))'
 
     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] }])
@@ -56,25 +66,12 @@ 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]
@@ -91,20 +88,12 @@ 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
 
-    count_scope = count_scope.except(:select, :order)
+    q = q.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' => updated_at).tap do |json|
+              .merge(updated_at: post.updated_at_all).tap do |json|
         json['thumbnail'] =
             if post.thumbnail.attached?
               rails_storage_proxy_url(post.thumbnail, only_path: false)
@@ -112,7 +101,7 @@ class PostsController < ApplicationController
               nil
             end
       end
-    }, count: count_scope.group_values.present? ? count_scope.count.size : count_scope.count }
+    }, count: q.group_values.present? ? q.count.size : q.count }
   end
 
   def random

backend/app/models/event.rb

@@ -0,0 +1,9 @@
+class Event < ApplicationRecord
+  has_many :post_versions
+  has_many :tag_versions
+  has_many :material_versions
+  has_many :tag_description_versions
+  has_many :tag_group_versions
+
+  belongs_to :created_by_user, class_name: 'User', optional: true
+end

backend/app/models/history_access.rb

@@ -59,21 +59,20 @@ class HistoryAccess < ActiveSupport::CurrentAttributes
   end
 
   def self.json_reference(table, key, document)
-    # A scalar lookup avoids MySQL's semijoin rewrite losing the JSON row correlation.
-    "(SELECT 1 FROM JSON_TABLE(COALESCE(#{ document }, JSON_ARRAY()), " +
+    "NOT EXISTS (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 } LIMIT 1) IS NULL"
+        "ON reference_entry.reference_id = blocked.#{ key })"
   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 }, ''), " +
         "' ', ',')), ',', '\",\"'), ']')"
-    "(SELECT 1 FROM JSON_TABLE(#{ array }, '$[*]' " +
+    "NOT EXISTS (SELECT 1 FROM JSON_TABLE(#{ array }, '$[*]' " +
         "COLUMNS (reference_id VARCHAR(255) PATH '$')) reference_entry " +
         "JOIN (#{ discarded_keys(table, key) }) blocked " +
-        "ON reference_entry.reference_id = CAST(blocked.#{ key } AS CHAR) LIMIT 1) IS NULL"
+        "ON reference_entry.reference_id = CAST(blocked.#{ key } AS CHAR))"
   end
 
   def self.snapshot_reference(model, row, external: false)
@@ -92,8 +91,8 @@ class HistoryAccess < ActiveSupport::CurrentAttributes
       match += ' AND reference_version.version_no = tag_reference.version_no'
       latest = ''
     end
-    "(SELECT 1 FROM #{ source } JOIN #{ table } reference_version ON #{ match } " +
-        "WHERE NOT (#{ sql(model, 'reference_version') }) #{ latest } LIMIT 1) IS NULL"
+    "NOT EXISTS (SELECT 1 FROM #{ source } JOIN #{ table } reference_version ON #{ match } " +
+        "WHERE NOT (#{ sql(model, 'reference_version') }) #{ latest })"
   end
 
   def self.reference_sql(table, row)
@@ -110,15 +109,11 @@ 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, '$**.name'), JSON_ARRAY()))"
-      # DISTINCT prevents merging this independent name set into the correlated scan.
-      # Keep byte-distinct names even when the column collation considers them equal.
-      private_names = 'SELECT DISTINCT private_name.name, ' +
-          'CAST(private_name.name AS BINARY) AS name_bytes FROM tag_versions private_tag ' +
+      ["NOT EXISTS (SELECT 1 FROM tag_versions private_tag " +
           "JOIN (#{ discarded_keys('tag_versions', 'tag_id') }) blocked " +
-          'ON blocked.tag_id = private_tag.tag_id ' +
+          "ON blocked.tag_id = private_tag.tag_id " +
           "JOIN JSON_TABLE(#{ names }, '$[*]' COLUMNS (name TEXT PATH '$')) private_name " +
-          "WHERE private_name.name <> ''"
-      ["NOT EXISTS (SELECT 1 FROM (#{ private_names }) private_name WHERE " +
+          "WHERE private_name.name <> '' AND " +
           "LOCATE(CONCAT(' ', private_name.name, ' '), " +
           "CONCAT(' ', COALESCE(#{ row }.linked_tags, ''), ' ')) > 0)"]
     when 'tag_versions'

backend/app/models/material_version.rb

@@ -11,7 +11,5 @@ class MaterialVersion < ApplicationRecord
   belongs_to :parent, class_name: 'Material', optional: true
   belongs_to :updated_by_user, class_name: 'User', optional: true
 
-  def export_paths_hash
-    export_paths_json || {}
-  end
+  def export_paths_hash = export_paths_json || { }
 end

backend/app/models/version_record.rb

@@ -19,6 +19,8 @@ module VersionRecord
 
     belongs_to :created_by_user, class_name: 'User', optional: true
 
+    belongs_to :event
+
     enum :event_type, event_type_map, prefix: true, validate: true
 
     validates :version_no, presence: true, numericality: { only_integer: true, greater_than: 0 }

backend/app/services/material_version_recorder.rb

@@ -1,20 +1,23 @@
 class MaterialVersionRecorder < VersionRecorder
   EVENT_TYPES = ['create', 'update', 'discard', 'restore'].freeze
 
-  def self.record! material:, event_type:, created_by_user:, file_snapshot: nil
-    new(material:, event_type:, created_by_user:, file_snapshot:).record!
+  def self.record! material:, event_type:, event:, created_by_user:, file_snapshot: nil
+    new(material:, event_type:, event:, created_by_user:, file_snapshot:).record!
   end
 
-  def initialize material:, event_type:, created_by_user:, file_snapshot: nil
+  def initialize material:, event_type:, event:, created_by_user:, file_snapshot: nil
     @file_snapshot = file_snapshot
 
-    super(record: material, event_type:, created_by_user:)
+    super(record: material, event_type:, event:, created_by_user:)
   end
 
   def self.ensure_snapshot! material, created_by_user:
     return if material.material_versions.exists?
 
-    record!(material:, event_type: :create,
+    event = Event.create!(event_type: 'materials.create',
+                          created_by_user:,
+                          created_at: material.created_at)
+    record!(material:, event_type: :create, event:,
             created_by_user: material.created_by_user || created_by_user)
   end
 

backend/app/services/post_version_recorder.rb

@@ -1,16 +1,19 @@
 class PostVersionRecorder < VersionRecorder
-  def self.record! post:, event_type:, created_by_user:
-    new(post:, event_type:, created_by_user:).record!
+  def self.record! post:, event_type:, event:, created_by_user:
+    new(post:, event_type:, event:, created_by_user:).record!
   end
 
-  def initialize post:, event_type:, created_by_user:
-    super(record: post, event_type:, created_by_user:)
+  def initialize post:, event_type:, event:, created_by_user:
+    super(record: post, event_type:, event:, created_by_user:)
   end
 
   def self.ensure_snapshot! post, created_by_user:
     return if post.post_versions.exists?
 
-    record!(post:, event_type: :create, created_by_user:)
+    event = Event.create!(event_type: 'posts.create',
+                          created_by_user:,
+                          created_at: post.created_at)
+    record!(post:, event_type: :create, event:, created_by_user:)
   end
 
   private

backend/app/services/tag_version_recorder.rb

@@ -1,13 +1,13 @@
 class TagVersionRecorder < VersionRecorder
-  def self.record! tag:, event_type:, created_by_user:, **_options
+  def self.record! tag:, event_type:, event:, created_by_user:, **_options
     Tag.transaction do
       SharedResourceIdAllocator.lock_space!(Tag, 'tags')
-      new(tag:, event_type:, created_by_user:).record!
+      new(tag:, event_type:, event:, created_by_user:).record!
     end
   end
 
-  def initialize tag:, event_type:, created_by_user:
-    super(record: tag, event_type:, created_by_user:)
+  def initialize tag:, event_type:, event:, created_by_user:
+    super(record: tag, event_type:, event:, created_by_user:)
   end
 
   private

backend/app/services/version_recorder.rb

@@ -1,9 +1,10 @@
 class VersionRecorder
   EVENT_TYPES = ['create', 'update', 'discard', 'restore'].freeze
 
-  def initialize record:, event_type:, created_by_user:
+  def initialize record:, event_type:, event:, created_by_user:
     @record = record
     @event_type = event_type.to_s
+    @event = event
     @created_by_user = created_by_user
 
     validate_event_type!
@@ -42,8 +43,9 @@ class VersionRecorder
   def base_attributes latest
     { version_no: (latest&.version_no || 0) + 1,
       event_type: @event_type,
-      created_at: Time.current,
-      created_by_user: @created_by_user }
+      event: @event,
+      created_by_user: @created_by_user,
+      created_at: Time.current }
   end
 
   def update_record_version_no! version_no

backend/db/migrate/20261102000000_create_events.rb

@@ -0,0 +1,19 @@
+class CreateEvents < ActiveRecord::Migration[8.0]
+  def change
+    create_table :events do |t|
+      t.string :event_type, null: false, index: true
+      t.text :reason
+      t.references :reverted_from_event, foreign_key: { to_table: :events }
+      t.json :metadata
+      t.binary :ip_address, limit: 16, index: true
+      t.references :created_by_user, index: true, foreign_key: false
+      t.datetime :created_at, null: false, index: true
+    end
+
+    add_reference :post_versions, :event, foreign_key: true, after: :original_created_before
+    add_reference :tag_versions, :event, foreign_key: true, after: :deprecated_at
+    add_reference :material_versions, :event, foreign_key: true
+    add_reference :tag_description_versions, :event, foreign_key: true, after: :source_version_no
+    add_reference :tag_group_versions, :event, foreign_key: true, after: :placements
+  end
+end

backend/db/migrate/20261102010000_backfill_events_from_existing_versions.rb

@@ -0,0 +1,207 @@
+class BackfillEventsFromExistingVersions < ActiveRecord::Migration[8.0]
+  class MigrationEvent < ActiveRecord::Base
+    self.table_name = 'events'
+  end
+
+  class MigrationPostVersion < ActiveRecord::Base
+    self.table_name = 'post_versions'
+  end
+
+  class MigrationTagVersion < ActiveRecord::Base
+    self.table_name = 'tag_versions'
+  end
+
+  class MigrationMaterialVersion < ActiveRecord::Base
+    self.table_name = 'material_versions'
+  end
+
+  class MigrationTagDescriptionVersion < ActiveRecord::Base
+    self.table_name = 'tag_description_versions'
+  end
+
+  class MigrationTagGroupVersion < ActiveRecord::Base
+    self.table_name = 'tag_group_versions'
+  end
+
+  class MigrationLocale < ActiveRecord::Base
+    self.table_name = 'locales'
+  end
+
+  def up
+    # create → posts.create
+    # update → posts.update
+    raise if MigrationPostVersion.where.not(event_type: ['create', 'update']).exists?
+
+    # create → materials.create
+    # update → materials.update
+    if MigrationMaterialVersion.where.not(event_type: ['create', 'update']).exists?
+      raise
+    end
+
+    # create → posts.create / posts.update / materials.create / materials.update / unknown
+    # update → tags.update / locales.create
+    # discard → unknown
+    if MigrationTagVersion.where.not(event_type: ['create', 'update', 'discard']).exists?
+      raise
+    end
+
+    # create → tag_descriptions.create
+    # update → tag_descriptions.update
+    if MigrationTagDescriptionVersion.where.not(event_type: ['create', 'update']).exists?
+      raise
+    end
+
+    # create → tag_groups.create
+    # update → tag_groups.update
+    if MigrationTagGroupVersion.where.not(event_type: ['create', 'update']).exists?
+      raise
+    end
+
+    # post_versions の Backfill
+    MigrationPostVersion.find_each do |pv|
+      ev = MigrationEvent.create!(event_type: "posts.#{ pv.event_type }",
+                                  reason: nil,
+                                  reverted_from_event_id: nil,
+                                  metadata: nil,
+                                  ip_address: nil,
+                                  created_by_user_id: pv.created_by_user_id,
+                                  created_at: pv.created_at)
+      pv.update_columns(event_id: ev.id)
+    end
+
+    # material_versions の Backfill
+    MigrationMaterialVersion.find_each do |m|
+      ev = MigrationEvent.create!(event_type: "materials.#{ m.event_type }",
+                                  reason: nil,
+                                  reverted_from_event_id: nil,
+                                  metadata: nil,
+                                  ip_address: nil,
+                                  created_by_user_id: m.created_by_user_id,
+                                  created_at: m.created_at)
+      m.update_columns(event_id: ev.id)
+    end
+
+    # ロカール追加に伴ふ該当語言のタグ名称追加異動のみ分離
+    ids_cause_of_locale_creation = []
+    MigrationLocale.where('created_at > ?', MigrationLocale.minimum(:created_at)).find_each do |l|
+      ev = MigrationEvent.create!(event_type: 'locales.create',
+                                  reason: nil,
+                                  reverted_from_event_id: nil,
+                                  metadata: nil,
+                                  ip_address: nil,
+                                  created_by_user_id: nil,
+                                  created_at: l.created_at)
+
+      MigrationTagVersion
+          .where('created_at > ?', l.created_at)
+          .where(event_type: 'update', event_id: nil)
+          .find_each do |t|
+        next unless t.names.key?(l.language_code)
+
+        prev = MigrationTagVersion.find_by(tag_id: t.tag_id, version_no: t.version_no - 1)
+        next if prev.nil? || prev.names.key?(l.language_code)
+
+        t.update_columns(event_id: ev.id)
+
+        ids_cause_of_locale_creation << t.id
+      end
+
+      ev.destroy! unless MigrationTagVersion.where(event_id: ev.id).exists?
+    end
+
+    # tag_versions の Backfill
+    MigrationTagVersion.where.not(id: ids_cause_of_locale_creation).find_each do |t|
+      ev =
+          case t.event_type
+          when 'create'
+            post =
+                MigrationPostVersion
+                .where('JSON_CONTAINS(tags_json, ?) <> 0', { tag_id: t.tag_id }.to_json)
+                .find_by(created_at: MigrationPostVersion
+                                     .where('JSON_CONTAINS(tags_json, ?) <> 0',
+                                            { tag_id: t.tag_id }.to_json)
+                                     .minimum(:created_at))
+            material =
+                MigrationMaterialVersion
+                .where(tag_id: t.tag_id)
+                .find_by(created_at: MigrationMaterialVersion
+                                     .where(tag_id: t.tag_id)
+                                     .minimum(:created_at))
+            if post
+              if material
+                if post.created_at < material.created_at
+                  MigrationEvent.find(post.event_id)
+                else
+                  MigrationEvent.find(material.event_id)
+                end
+              else
+                MigrationEvent.find(post.event_id)
+              end
+            else
+              if material
+                MigrationEvent.find(material.event_id)
+              else
+                MigrationEvent.create!(event_type: 'unknown',
+                                       reason: nil,
+                                       reverted_from_event_id: nil,
+                                       metadata: nil,
+                                       ip_address: nil,
+                                       created_by_user_id: t.created_by_user_id,
+                                       created_at: t.created_at)
+              end
+            end
+          when 'update'
+            MigrationEvent.create!(event_type: 'tags.update',
+                                   reason: nil,
+                                   reverted_from_event_id: nil,
+                                   metadata: nil,
+                                   ip_address: nil,
+                                   created_by_user_id: t.created_by_user_id,
+                                   created_at: t.created_at)
+          when 'discard'
+            MigrationEvent.create!(event_type: 'unknown',
+                                   reason: nil,
+                                   reverted_from_event_id: nil,
+                                   metadata: nil,
+                                   ip_address: nil,
+                                   created_by_user_id: t.created_by_user_id,
+                                   created_at: t.created_at)
+          end
+      t.update_columns(event_id: ev.id)
+    end
+
+    # tag_description_versions の Backfill
+    MigrationTagDescriptionVersion.find_each do |td|
+      ev = MigrationEvent.create!(event_type: "tag_descriptions.#{ td.event_type }",
+                                  reason: nil,
+                                  reverted_from_event_id: nil,
+                                  metadata: nil,
+                                  ip_address: nil,
+                                  created_by_user_id: td.created_by_user_id,
+                                  created_at: td.created_at)
+      td.update_columns(event_id: ev.id)
+    end
+
+    # tag_group_versions の Backfill
+    MigrationTagGroupVersion.find_each do |tg|
+      ev = MigrationEvent.create!(event_type: "tag_groups.#{ tg.event_type }",
+                                  reason: nil,
+                                  reverted_from_event_id: nil,
+                                  metadata: nil,
+                                  ip_address: nil,
+                                  created_by_user_id: tg.created_by_user_id,
+                                  created_at: tg.created_at)
+      tg.update_columns(event_id: ev.id)
+    end
+
+    change_column_null :post_versions, :event_id, false
+    change_column_null :tag_versions, :event_id, false
+    change_column_null :material_versions, :event_id, false
+    change_column_null :tag_description_versions, :event_id, false
+    change_column_null :tag_group_versions, :event_id, false
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration, '戻せません．'
+  end
+end

backend/db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
+ActiveRecord::Schema[8.0].define(version: 2026_11_02_010000) do
   create_table "active_storage_attachments", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -48,6 +48,21 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
     t.index ["tag_id"], name: "index_deerjikists_on_tag_id"
   end
 
+  create_table "events", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "event_type", null: false
+    t.text "reason"
+    t.bigint "reverted_from_event_id"
+    t.json "metadata"
+    t.binary "ip_address", limit: 16
+    t.bigint "created_by_user_id"
+    t.datetime "created_at", null: false
+    t.index ["created_at"], name: "index_events_on_created_at"
+    t.index ["created_by_user_id"], name: "index_events_on_created_by_user_id"
+    t.index ["event_type"], name: "index_events_on_event_type"
+    t.index ["ip_address"], name: "index_events_on_ip_address"
+    t.index ["reverted_from_event_id"], name: "index_events_on_reverted_from_event_id"
+  end
+
   create_table "external_tags", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "platform", limit: 16, null: false
     t.string "name", null: false
@@ -250,8 +265,10 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
     t.string "source_path"
     t.string "source_file_id"
     t.string "normalized_source_key"
+    t.bigint "event_id", null: false
     t.index ["created_by_user_id"], name: "index_material_versions_on_created_by_user_id"
     t.index ["discarded_at"], name: "index_material_versions_on_discarded_at"
+    t.index ["event_id"], name: "index_material_versions_on_event_id"
     t.index ["file_blob_id"], name: "index_material_versions_on_file_blob_id"
     t.index ["material_id", "version_no"], name: "index_material_versions_on_material_id_and_version_no", unique: true
     t.index ["material_id"], name: "index_material_versions_on_material_id"
@@ -380,10 +397,12 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
     t.text "parent_post_ids", null: false
     t.datetime "original_created_from"
     t.datetime "original_created_before"
+    t.bigint "event_id", null: false
     t.datetime "created_at", null: false
     t.bigint "created_by_user_id"
     t.integer "video_ms"
     t.index ["created_by_user_id"], name: "index_post_versions_on_created_by_user_id"
+    t.index ["event_id"], name: "index_post_versions_on_event_id"
     t.index ["post_id", "version_no"], name: "index_post_versions_on_post_id_and_version_no", unique: true
     t.index ["post_id"], name: "index_post_versions_on_post_id"
     t.index ["video_ms", "post_id"], name: "idx_post_versions_video_ms_post_id"
@@ -448,9 +467,11 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
     t.text "body", null: false
     t.string "source_language_code", limit: 16
     t.integer "source_version_no"
+    t.bigint "event_id", null: false
     t.bigint "created_by_user_id"
     t.datetime "created_at", null: false
     t.index ["created_by_user_id"], name: "index_tag_description_versions_on_created_by_user_id"
+    t.index ["event_id"], name: "index_tag_description_versions_on_event_id"
     t.index ["tag_id", "language_code", "version_no"], name: "idx_on_tag_id_language_code_version_no_ced77e57e6", unique: true
     t.index ["tag_id", "source_language_code", "source_version_no"], name: "fk_rails_4f13094dbc"
     t.index ["tag_id"], name: "index_tag_description_versions_on_tag_id"
@@ -533,9 +554,11 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
     t.text "description"
     t.json "members", null: false
     t.json "placements", null: false
+    t.bigint "event_id", null: false
     t.bigint "created_by_user_id"
     t.datetime "created_at", null: false
     t.index ["created_by_user_id"], name: "index_tag_group_versions_on_created_by_user_id"
+    t.index ["event_id"], name: "index_tag_group_versions_on_event_id"
     t.index ["tag_group_id", "version_no"], name: "index_tag_group_versions_on_tag_group_id_and_version_no", unique: true
     t.index ["tag_group_id"], name: "index_tag_group_versions_on_tag_group_id"
     t.check_constraint "`version_no` > 0", name: "chk_tag_group_versions_version_no_positive"
@@ -611,11 +634,13 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
     t.text "aliases", null: false
     t.text "parent_tag_ids", null: false
     t.datetime "deprecated_at"
+    t.bigint "event_id", null: false
     t.datetime "created_at", null: false
     t.bigint "created_by_user_id"
     t.json "names", null: false
     t.index ["created_at"], name: "index_tag_versions_on_created_at"
     t.index ["created_by_user_id", "created_at"], name: "index_tag_versions_on_created_by_user_id_and_created_at", order: { created_at: :desc }
+    t.index ["event_id"], name: "index_tag_versions_on_event_id"
     t.index ["tag_id", "created_at"], name: "index_tag_versions_on_tag_id_and_created_at", order: { created_at: :desc }
     t.index ["tag_id", "version_no"], name: "index_tag_versions_on_tag_id_and_version_no", unique: true
     t.check_constraint "`version_no` > 0", name: "tag_versions_version_no_positive"
@@ -771,6 +796,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
 
   add_foreign_key "active_storage_attachments", "active_storage_blobs", column: "blob_id"
   add_foreign_key "active_storage_variant_records", "active_storage_blobs", column: "blob_id"
+  add_foreign_key "events", "events", column: "reverted_from_event_id"
   add_foreign_key "gekanator_ai_runs", "gekanator_question_suggestions"
   add_foreign_key "gekanator_games", "posts", column: "correct_post_id"
   add_foreign_key "gekanator_games", "posts", column: "guessed_post_id"
@@ -792,6 +818,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
   add_foreign_key "material_sync_sources", "users", column: "created_by_user_id"
   add_foreign_key "material_sync_sources", "users", column: "updated_by_user_id"
   add_foreign_key "material_sync_suppressions", "users", column: "created_by_user_id"
+  add_foreign_key "material_versions", "events"
   add_foreign_key "material_versions", "materials"
   add_foreign_key "material_versions", "materials", column: "parent_id"
   add_foreign_key "material_versions", "users", column: "created_by_user_id"
@@ -813,10 +840,12 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
   add_foreign_key "post_tags", "posts"
   add_foreign_key "post_tags", "tags"
   add_foreign_key "post_tags", "users", column: "created_user_id"
+  add_foreign_key "post_versions", "events"
   add_foreign_key "post_versions", "posts"
   add_foreign_key "post_versions", "users", column: "created_by_user_id"
   add_foreign_key "posts", "users", column: "uploaded_user_id"
   add_foreign_key "settings", "users"
+  add_foreign_key "tag_description_versions", "events"
   add_foreign_key "tag_description_versions", "tag_description_versions", column: ["tag_id", "source_language_code", "source_version_no"], primary_key: ["tag_id", "language_code", "version_no"]
   add_foreign_key "tag_descriptions", "languages", column: "language_code", primary_key: "code"
   add_foreign_key "tag_descriptions", "tag_description_versions", column: ["tag_id", "source_language_code", "source_version_no"], primary_key: ["tag_id", "language_code", "version_no"]
@@ -835,6 +864,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
   add_foreign_key "tag_group_tags", "tag_groups"
   add_foreign_key "tag_group_tags", "tags"
   add_foreign_key "tag_group_tags", "users", column: "created_by_user_id"
+  add_foreign_key "tag_group_versions", "events"
   add_foreign_key "tag_groups", "users", column: "created_by_user_id"
   add_foreign_key "tag_groups", "users", column: "updated_by_user_id"
   add_foreign_key "tag_implications", "tags"
@@ -844,6 +874,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_10_15_010000) do
   add_foreign_key "tag_names", "tags"
   add_foreign_key "tag_similarities", "tags"
   add_foreign_key "tag_similarities", "tags", column: "target_tag_id"
+  add_foreign_key "tag_versions", "events"
   add_foreign_key "tag_versions", "users", column: "created_by_user_id"
   add_foreign_key "theatre_comments", "theatres"
   add_foreign_key "theatre_comments", "users"

backend/spec/db/tag_group_constraints_spec.rb

@@ -102,6 +102,7 @@ RSpec.describe 'Tag group persistence constraints' do
     6.times { nodes = [{ 'tag_id' => tag.id, 'children' => nodes }] }
     reject_statement do
       insert_group_row('tag_group_versions', {
+          event_id: create_event!(event_type: 'unknown').id,
           tag_group_id: group_id, version_no: 2, event_type: 'update', name: '制約確認',
           members: [{ 'tag_id' => tag.id, 'version_no' => tag.version_no }].to_json,
           placements: nodes.to_json, created_at: Time.current })

backend/spec/db/tag_version_names_spec.rb

@@ -10,6 +10,7 @@ RSpec.describe 'TagVersion names database constraint' do
 
   def insert_snapshot!(snapshot)
     TagVersion.insert_all!([{ tag_id: tag.id, version_no: 1, event_type: 'create',
+                             event_id: create_event!(event_type: 'unknown').id,
                              name: 'snapshot_name', category: 'general',
                              aliases: '', parent_tag_ids: '', names: snapshot,
                              created_at: Time.current }])

backend/spec/models/history_access_spec.rb

@@ -9,7 +9,9 @@ RSpec.describe HistoryAccess do
     locale
     rows = ['ja', 'ain'].flat_map do |language|
       ['create', 'discard', 'restore'].each_with_index.map do |event, index|
-        TagDescriptionVersion.create!(tag_id: tag.id, language_code: language,
+        TagDescriptionVersion.create!(
+            event_id: create_event!(event_type: 'unknown').id,
+            tag_id: tag.id, language_code: language,
             version_no: index + 1, event_type: language == 'ain' ? 'update' : event,
             body: "#{ language } #{ index }", created_at: Time.utc(2024))
       end
@@ -28,7 +30,9 @@ RSpec.describe HistoryAccess do
     public_metadata = described_class.set(user: nil) { described_class.authority }
     admin = create(:user, :admin)
     admin_metadata = described_class.set(user: admin) { described_class.authority }
-    TagVersion.create!(tag:, version_no: 1, event_type: 'discard', name: 'private',
+    TagVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        tag:, version_no: 1, event_type: 'discard', name: 'private',
         category: 'general',
         names: { ja: { name: 'private', script_code: 'Jpan',
                        auto_generated: false, aliases: [] } },
@@ -52,7 +56,9 @@ RSpec.describe HistoryAccess do
     blob = ActiveStorage::Blob.create_before_direct_upload!(filename: 'private.png',
         byte_size: 1, checksum: Base64.strict_encode64('checksum'), content_type: 'image/png')
     ActiveStorage::Attachment.create!(name: 'thumbnail', record: post, blob:)
-    PostVersion.create!(post:, version_no: 1, event_type: 'discard', url: post.url,
+    PostVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        post:, version_no: 1, event_type: 'discard', url: post.url,
         title: 'private', tags: '', tags_json: [], parent_post_ids: '', created_at: Time.utc(2024))
     variant = ActiveStorage::VariantRecord.create!(blob:, variation_digest: 'spec-variation')
     derived = ActiveStorage::Blob.create_before_direct_upload!(filename: 'derived.png',
@@ -78,7 +84,9 @@ RSpec.describe 'Counts artifact policy and external references' do
 
   it 'does not expose a private linked tag name through an external history snapshot' do
     tag = create(:tag, primary_name: 'private-linked-name')
-    TagVersion.create!(tag:, version_no: 1, event_type: 'discard', name: 'private-linked-name',
+    TagVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        tag:, version_no: 1, event_type: 'discard', name: 'private-linked-name',
         category: 'general', aliases: '', parent_tag_ids: '', created_at: Time.utc(2024),
         names: { ja: { name: 'private-linked-name', script_code: 'Jpan',
                        auto_generated: false, aliases: [] } })
@@ -87,7 +95,9 @@ RSpec.describe 'Counts artifact policy and external references' do
         name: 'nico:public-external', linked_tags: 'private-linked-name',
         created_at: Time.utc(2024))
     post = create(:post)
-    snapshot = PostVersion.create!(post:, version_no: 1, event_type: 'create',
+    snapshot = PostVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        post:, version_no: 1, event_type: 'create',
         title: 'external reference', url: post.url, tags: '',
         tags_json: [{ external_tag_id: external.id }], parent_post_ids: '',
         created_at: Time.utc(2024, 2))
@@ -112,13 +122,17 @@ RSpec.describe 'Counts artifact policy and external references' do
     child = create(:tag, primary_name: 'referencing child')
     [[parent, 'discard', '', 'private parent'],
      [child, 'create', parent.id.to_s, 'referencing child']].each do |tag, event, parents, name|
-      TagVersion.create!(tag:, version_no: 1, event_type: event, name:,
+      TagVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          tag:, version_no: 1, event_type: event, name:,
           category: 'general', aliases: '', parent_tag_ids: parents, created_at: Time.utc(2023),
           names: { ja: { name:, script_code: 'Jpan',
                          auto_generated: false, aliases: [] } })
     end
     post = create(:post)
-    row = PostVersion.create!(post:, version_no: 1, event_type: 'create', title: 'snapshot',
+    row = PostVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        post:, version_no: 1, event_type: 'create', title: 'snapshot',
         url: post.url, tags: '', parent_post_ids: '',
         tags_json: [{ tag_id: child.id, version_no: 1, name: 'referencing child', sections: [] }],
         created_at: Time.utc(2024))

backend/spec/models/locale_activation_spec.rb

@@ -23,9 +23,22 @@ RSpec.describe 'Locale activation', type: :model do
         .and_raise('backfill failed')
   end
 
+  it 'groups all tag histories from locale creation into one event' do
+    previous_ids = TagVersion.pluck(:id)
+
+    expect { build_locale.save! }.to change { event_rows.length }.by(1)
+
+    event = event_rows.last
+    expect(event).to include('event_type' => 'locales.create', 'created_by_user_id' => nil)
+    versions = TagVersion.where.not(id: previous_ids)
+    expect(versions.pluck(:tag_id)).to include(first.id, second.id)
+    expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
+  end
+
   it 'rolls back a newly created locale and the preceding generated names' do
     locale = build_locale
     fail_second_generation!
+    events = event_rows
 
     expect { locale.save! }.to raise_error('backfill failed')
 
@@ -33,6 +46,7 @@ RSpec.describe 'Locale activation', type: :model do
     expect(generated_names).to be_empty
     expect(first.reload.name('ja')).to eq('activation_first')
     expect(second.reload.name('ja')).to eq('activation_second')
+    expect(event_rows).to eq(events)
   end
 
   it 'does not backfill while the locale is inactive' do
@@ -45,7 +59,14 @@ RSpec.describe 'Locale activation', type: :model do
     locale = build_locale(deprecated_at: Time.current)
     locale.save!
 
-    locale.update!(deprecated_at: nil)
+    previous_ids = TagVersion.pluck(:id)
+    expect { locale.update!(deprecated_at: nil) }.to change { event_rows.length }.by(1)
+
+    event = event_rows.last
+    expect(event).to include('event_type' => 'locales.restore', 'created_by_user_id' => nil)
+    versions = TagVersion.where.not(id: previous_ids)
+    expect(versions.pluck(:tag_id)).to include(first.id, second.id)
+    expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
 
     expect(generated_names.pluck(:tag_id)).to contain_exactly(first.id, second.id)
     expect(generated_names).to all(have_attributes(
@@ -57,11 +78,13 @@ RSpec.describe 'Locale activation', type: :model do
     locale.save!
     previous_deprecated_at = locale.reload.deprecated_at
     fail_second_generation!
+    events = event_rows
 
     expect { locale.update!(deprecated_at: nil) }.to raise_error('backfill failed')
 
     expect(locale.reload.deprecated_at).to eq(previous_deprecated_at)
     expect(generated_names).to be_empty
+    expect(event_rows).to eq(events)
   end
 
   it 'preserves a human primary through deactivation and repeated activation' do

backend/spec/models/post_version_spec.rb

@@ -12,20 +12,20 @@ RSpec.describe PostVersion, type: :model do
 
   let!(:post_version) do
     PostVersion.create!(
-      post: post_record,
-      version_no: 1,
-      event_type: 'create',
-      title: post_record.title,
-      url: post_record.url,
-      thumbnail_base: post_record.thumbnail_base,
-      tags: post_record.snapshot_tag_names.join(' '),
-      tags_json: post_record.snapshot_tags_json,
-      parent_post_ids: post_record.snapshot_parent_post_ids.join(' '),
-      original_created_from: post_record.original_created_from,
-      original_created_before: post_record.original_created_before,
-      created_at: Time.current,
-      created_by_user: nil
-    )
+        event_id: create_event!(event_type: 'unknown').id,
+        post: post_record,
+        version_no: 1,
+        event_type: 'create',
+        title: post_record.title,
+        url: post_record.url,
+        thumbnail_base: post_record.thumbnail_base,
+        tags: post_record.snapshot_tag_names.join(' '),
+        tags_json: post_record.snapshot_tags_json,
+        parent_post_ids: post_record.snapshot_parent_post_ids.join(' '),
+        original_created_from: post_record.original_created_from,
+        original_created_before: post_record.original_created_before,
+        created_at: Time.current,
+        created_by_user: nil)
   end
 
   it 'is read only after create' do

backend/spec/models/tag_name_sanitisation_rule_spec.rb

@@ -34,6 +34,31 @@ RSpec.describe TagNameSanitisationRule, type: :model do
       described_class.create!(priority: 10, source_pattern: 'foo_', replacement: 'foo')
     end
 
+    it 'groups renames, merges and affected post histories into one event' do
+      target = create(:tag, primary_name: 'foobar')
+      source = create(:tag, primary_name: 'temporary_source')
+      renamed = create(:tag, primary_name: 'temporary_rename')
+      source.tag_name('ja').update_columns(name: 'foo_bar')
+      renamed.tag_name('ja').update_columns(name: 'foo_baz')
+      post = create(:post)
+      PostTag.create!(post:, tag: source)
+      previous_tag_ids = TagVersion.pluck(:id)
+      previous_post_ids = PostVersion.pluck(:id)
+
+      expect { described_class.apply! }.to change { event_rows.length }.by(1)
+
+      event = event_rows.last
+      expect(event).to include(
+          'event_type' => 'tag_name_sanitisation_rules.apply', 'created_by_user_id' => nil)
+      tag_versions = TagVersion.where.not(id: previous_tag_ids)
+      expect(tag_versions.pluck(:tag_id).uniq).to contain_exactly(target.id, source.id, renamed.id)
+      expect(tag_versions.pluck(:event_type)).to include('discard', 'update')
+      expect(tag_versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
+      post_versions = PostVersion.where.not(id: previous_post_ids)
+      expect(post_versions.pluck(:post_id).uniq).to eq([post.id])
+      expect(post_versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
+    end
+
     [:primary, :alias].each do |source_kind|
       it "keeps the primary identity when a #{ source_kind } collides within its Tag" do
         tag = create(:tag, primary_name: source_kind == :primary ? 'temporary' : 'foobar')
@@ -83,6 +108,7 @@ RSpec.describe TagNameSanitisationRule, type: :model do
       PostTag.create!(post:, tag: source)
       models = [Tag, TagName, TagVersion, TagDescription, TagDescriptionVersion, PostTag]
       snapshots = models.map { |model| model.order(*Array(model.primary_key)).map(&:attributes) }
+      events = event_rows
 
       expect { described_class.apply! }.to raise_error(ActiveRecord::RecordInvalid)
 
@@ -90,6 +116,7 @@ RSpec.describe TagNameSanitisationRule, type: :model do
         model.order(*Array(model.primary_key)).map(&:attributes)
       end
       expect(after_state).to eq(snapshots)
+      expect(event_rows).to eq(events)
       expect(post.reload.tags).to contain_exactly(source)
       expect(target.reload.name('ja')).to eq('foobar')
     end

backend/spec/models/tag_spec.rb

@@ -665,20 +665,20 @@ RSpec.describe Tag, type: :model do
 
     def create_post_version_for!(post, version_no: 1, event_type: 'create', created_by_user: nil)
       PostVersion.create!(
-        post: post,
-        version_no: version_no,
-        event_type: event_type,
-        title: post.title,
-        url: post.url,
-        thumbnail_base: post.thumbnail_base,
-        tags: snapshot_tags(post),
-        tags_json: post.snapshot_tags_json,
-        parent_post_ids: post.snapshot_parent_post_ids.join(' '),
-        original_created_from: post.original_created_from,
-        original_created_before: post.original_created_before,
-        created_at: Time.current,
-        created_by_user: created_by_user
-      )
+          event_id: create_event!(event_type: 'unknown').id,
+          post: post,
+          version_no: version_no,
+          event_type: event_type,
+          title: post.title,
+          url: post.url,
+          thumbnail_base: post.thumbnail_base,
+          tags: snapshot_tags(post),
+          tags_json: post.snapshot_tags_json,
+          parent_post_ids: post.snapshot_parent_post_ids.join(' '),
+          original_created_from: post.original_created_from,
+          original_created_before: post.original_created_before,
+          created_at: Time.current,
+          created_by_user: created_by_user)
     end
 
     context 'when post versions are enabled' do

backend/spec/models/version_record_spec.rb

@@ -6,17 +6,18 @@ RSpec.describe VersionRecord, type: :model do
 
   it 'makes TagVersion read only after create' do
     version = TagVersion.create!(
-      tag: tag,
-      version_no: 1,
-      event_type: 'create',
-      name: primary_tag_name_for(tag, 'ja').name,
-      category: tag.category,
-      aliases: '',
-      names: { ja: { name: primary_tag_name_for(tag, 'ja').name,
-                     script_code: 'Jpan', auto_generated: false, aliases: [] } },
-      parent_tag_ids: '',
-      created_at: Time.current,
-      created_by_user: nil)
+        event_id: create_event!(event_type: 'unknown').id,
+        tag: tag,
+        version_no: 1,
+        event_type: 'create',
+        name: primary_tag_name_for(tag, 'ja').name,
+        category: tag.category,
+        aliases: '',
+        names: { ja: { name: primary_tag_name_for(tag, 'ja').name,
+                       script_code: 'Jpan', auto_generated: false, aliases: [] } },
+        parent_tag_ids: '',
+        created_at: Time.current,
+        created_by_user: nil)
 
     expect {
       version.update!(name: 'changed')
@@ -25,17 +26,18 @@ RSpec.describe VersionRecord, type: :model do
 
   it 'prevents TagVersion destroy' do
     version = TagVersion.create!(
-      tag: tag,
-      version_no: 1,
-      event_type: 'create',
-      name: primary_tag_name_for(tag, 'ja').name,
-      category: tag.category,
-      aliases: '',
-      names: { ja: { name: primary_tag_name_for(tag, 'ja').name,
-                     script_code: 'Jpan', auto_generated: false, aliases: [] } },
-      parent_tag_ids: '',
-      created_at: Time.current,
-      created_by_user: nil)
+        event_id: create_event!(event_type: 'unknown').id,
+        tag: tag,
+        version_no: 1,
+        event_type: 'create',
+        name: primary_tag_name_for(tag, 'ja').name,
+        category: tag.category,
+        aliases: '',
+        names: { ja: { name: primary_tag_name_for(tag, 'ja').name,
+                       script_code: 'Jpan', auto_generated: false, aliases: [] } },
+        parent_tag_ids: '',
+        created_at: Time.current,
+        created_by_user: nil)
 
     expect {
       version.destroy!

backend/spec/rails_helper.rb

@@ -44,6 +44,7 @@ RSpec.configure do |config|
   end
 
   config.include TestRecords
+  config.include EventRecords
   config.include RakeTaskHelper
 
   # FactoryBot の create / create_list を使へるやぅにする

backend/spec/requests/counts_download_spec.rb

@@ -84,7 +84,9 @@ RSpec.describe 'Counts native GET acknowledgement', type: :request do
     expect(response).to have_http_status(:not_found)
     job, file, attempt = ready_job('json')
     record = create(:post)
-    PostVersion.create!(post: record, version_no: 1, event_type: 'discard', title: 'private',
+    PostVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        post: record, version_no: 1, event_type: 'discard', title: 'private',
         url: record.url, tags: '', tags_json: [], parent_post_ids: '', created_at: Time.utc(2024))
     get "/counts/export/files/#{ file }", params: { job:, attempt: }
     expect(response).to have_http_status(:not_found)

backend/spec/requests/counts_history_boundaries_spec.rb

@@ -8,7 +8,9 @@ RSpec.describe 'History boundaries shared with Counts', type: :request do
 
   before do
     ['create', 'discard'].each_with_index do |event, index|
-      TagDescriptionVersion.create!(tag_id: tag.id, language_code: 'ja',
+      TagDescriptionVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          tag_id: tag.id, language_code: 'ja',
           version_no: index + 1, event_type: event, body: 'private body',
           created_at: Time.utc(2024))
     end

backend/spec/requests/counts_spec.rb

@@ -10,12 +10,16 @@ RSpec.describe 'Legacy Counts API', type: :request do
                  category: 'general', sections: [] }
     [1, 2, 3].each do |number|
       time = Time.utc(2024, number == 3 ? 2 : 1, number, 0, 0)
-      PostVersion.create!(post:, version_no: number,
+      PostVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          post:, version_no: number,
           event_type: number == 1 ? 'create' : 'update',
           tags: '', url: post.url, title: "Snapshot #{ number }", parent_post_ids: '',
           tags_json: number == 1 ? [snapshot] : [],
           created_by_user: number == 3 ? nil : actor, created_at: time)
-      TagVersion.create!(tag:, version_no: number,
+      TagVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          tag:, version_no: number,
           event_type: number == 1 ? 'create' : 'update',
           name: 'counts tag', category: 'general', aliases: '', parent_tag_ids: '',
           names: { ja: { name: 'counts tag', script_code: 'Jpan',

backend/spec/requests/counts_table_spec.rb

@@ -14,7 +14,9 @@ RSpec.describe 'Counts table API', type: :request do
   end
 
   before do
-    TagVersion.create!(tag:, version_no: 1, event_type: 'create', name: 'alpha',
+    TagVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        tag:, version_no: 1, event_type: 'create', name: 'alpha',
         category: 'general', aliases: '', parent_tag_ids: '',
         names: { ja: { name: 'alpha', script_code: 'Jpan', auto_generated: false,  aliases: [] } },
         created_at: Time.utc(2023))
@@ -24,7 +26,9 @@ RSpec.describe 'Counts table API', type: :request do
         { tag_id: tag.id, version_no: 1, name: 'alpha', category: 'general', sections: [] },
         { external_tag_id: external.id }]
     [1, 2, 3].each do |number|
-      PostVersion.create!(post: record, version_no: number,
+      PostVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          post: record, version_no: number,
           event_type: number == 1 ? 'create' : 'update', url: record.url,
           title: "snapshot #{ number }", tags: '', parent_post_ids: '',
           tags_json: snapshots.first(number == 1 ? 2 : (number == 2 ? 1 : 0)),
@@ -134,7 +138,9 @@ RSpec.describe 'Counts table API', type: :request do
   end
 
   it 'checks the current latest flag beyond the execution timestamp' do
-    PostVersion.create!(post: record, version_no: 4, event_type: 'update',
+    PostVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        post: record, version_no: 4, event_type: 'update',
         url: record.url, title: 'after execution', tags: '', tags_json: [],
         parent_post_ids: '', created_at: Time.utc(2025, 2, 1))
     result = query
@@ -188,12 +194,16 @@ RSpec.describe 'Counts table API', type: :request do
       tag.tag_names.find_by!(language_code: 'ja', primary_flg: true)
           .update!(name: 'renamed-alpha')
       create(:tag_name, :alias, tag:, name: 'alpha-alias')
-      TagVersion.create!(tag:, version_no: 2, event_type: 'update', name: 'renamed-alpha',
+      TagVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          tag:, version_no: 2, event_type: 'update', name: 'renamed-alpha',
           category: 'general', aliases: 'alpha-alias', parent_tag_ids: '',
           names: { ja: { name: 'renamed-alpha', script_code: 'Jpan', auto_generated: false,
                          aliases: [{ name: 'alpha-alias', script_code: 'Jpan' }] } },
           created_at: Time.utc(2024, 2, 1))
-      PostVersion.create!(post: record, version_no: 4, event_type: 'update',
+      PostVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          post: record, version_no: 4, event_type: 'update',
           url: record.url, title: 'after rename', tags: '', parent_post_ids: '',
           tags_json: [{ tag_id: tag.id, version_no: 2, name: 'renamed-alpha',
                         category: 'general', sections: [] }],
@@ -257,7 +267,9 @@ RSpec.describe 'Counts table API', type: :request do
 
   it 'reports column overflow separately from malformed input' do
     101.times do |index|
-      PostVersion.create!(post: record, version_no: index + 4,
+      PostVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          post: record, version_no: index + 4,
           event_type: 'update', url: record.url, title: "column #{ index }",
           tags: '', tags_json: [], parent_post_ids: '', created_at: Time.utc(2024, 3))
     end
@@ -301,7 +313,9 @@ RSpec.describe 'Counts table API', type: :request do
         sign_in_as(create(:user, role)) if role
         # Equal timestamps deliberately require version ordering, not a date comparison.
         ['discard', 'restore', 'discard', 'restore'].each_with_index do |event, index|
-          PostVersion.create!(post: record, version_no: index + 4, event_type: event,
+          PostVersion.create!(
+              event_id: create_event!(event_type: 'unknown').id,
+              post: record, version_no: index + 4, event_type: event,
               url: record.url, title: event == 'restore' ? 'restored' : 'private snapshot',
               tags: '', tags_json: [], parent_post_ids: '', created_at: Time.utc(2024, 3))
         end
@@ -329,7 +343,9 @@ RSpec.describe 'Counts table API', type: :request do
       end
 
       it 'does not resolve private condition names even when the result set is empty' do
-        TagVersion.create!(tag:, version_no: 2, event_type: 'discard', name: 'secret tag',
+        TagVersion.create!(
+            event_id: create_event!(event_type: 'unknown').id,
+            tag:, version_no: 2, event_type: 'discard', name: 'secret tag',
             category: 'general', aliases: '', parent_tag_ids: '',
             names: { ja: { name: 'secret tag', script_code: 'Jpan', auto_generated: false, aliases: [] } },
             created_at: Time.utc(2024, 2))
@@ -345,7 +361,9 @@ RSpec.describe 'Counts table API', type: :request do
     end
   end
   it 'includes private history in the public timeline without an exclusion count' do
-    PostVersion.create!(post: record, version_no: 4, event_type: 'discard', url: record.url,
+    PostVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        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))
     result = query(mode: 'summary', rows: 'created_at:month', cols: 'event_type')

backend/spec/requests/materials_spec.rb

@@ -314,6 +314,7 @@ RSpec.describe 'Materials API', type: :request do
           .and change(Tag, :count).by(1)
           .and change(TagName, :count).by(1)
           .and change(MaterialVersion, :count).by(1)
+          .and change { event_rows.length }.by(1)
 
         expect(response).to have_http_status(:created)
 
@@ -325,6 +326,12 @@ RSpec.describe 'Materials API', type: :request do
         expect(material.file.attached?).to be(true)
         expect(material.version_no).to eq(1)
         expect(material.material_versions.first.event_type).to eq('create')
+        event = event_rows.last
+        expect(event).to include(
+            'event_type' => 'materials.create',
+            'created_by_user_id' => member_user.id)
+        expect(material.material_versions.first.event_id).to eq(event.fetch('id'))
+        expect(material.tag.tag_versions.pluck(:event_id)).to eq([event.fetch('id')])
         expect(material.material_export_items.first.export_path).to eq('伊地知ニジカ/created.png')
         expect(material.material_versions.first.export_paths_json).to eq(
           'legacy_drive' => '伊地知ニジカ/created.png'
@@ -509,6 +516,7 @@ RSpec.describe 'Materials API', type: :request do
             export_paths: { legacy_drive: '伊地知ニジカ/updated.jpg' }
           }
         end.to change(MaterialVersion, :count).by(2)
+            .and change { event_rows.length }.by(1)
 
         expect(response).to have_http_status(:ok)
 
@@ -517,6 +525,12 @@ RSpec.describe 'Materials API', type: :request do
         expect(material.tag.category).to eq('material')
         expect(material.url).to eq('https://example.com/updated-source')
         expect(material.updated_by_user).to eq(member_user)
+        event = event_rows.last
+        expect(event).to include(
+            'event_type' => 'materials.update',
+            'created_by_user_id' => member_user.id)
+        expect(material.material_versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
+        expect(material.tag.tag_versions.pluck(:event_id)).to eq([event.fetch('id')])
         expect(material.file.attached?).to be(true)
         expect(material.file.blob.id).not_to eq(old_blob_id)
         expect(ActiveStorage::Blob.where(id: old_blob_id).exists?).to be(true)
@@ -632,6 +646,7 @@ RSpec.describe 'Materials API', type: :request do
         MaterialVersionRecorder.record!(material:, event_type: :create,
                                         created_by_user: member_user)
         TagVersioning.ensure_snapshot!(tag, created_by_user: member_user)
+        events = event_rows
 
         expect do
           put "/materials/#{ material.id }", params: {
@@ -643,6 +658,7 @@ RSpec.describe 'Materials API', type: :request do
 
         expect(response).to have_http_status(:ok)
         expect(material.reload.version_no).to eq(1)
+        expect(event_rows).to eq(events)
       end
 
       it 'records update version when only export_path changes' do
@@ -807,6 +823,12 @@ RSpec.describe 'Materials API', type: :request do
 
     it 'creates source suppression as member' do
       sign_in_as(member_user)
+      materials = ['a', 'b'].map do |name|
+        Material.create!(
+            source_kind: 'google_drive_file', source_file_id: "blocked-#{ name }",
+            source_path: "伊地知ニジカ/危険素材/#{ name }.png",
+            url: "https://example.com/blocked-#{ name }", created_by_user: member_user)
+      end
 
       expect do
         post '/materials/suppressions', params: {
@@ -815,6 +837,7 @@ RSpec.describe 'Materials API', type: :request do
           reason: 'copyright_high_risk'
         }
       end.to change(MaterialSyncSuppression, :count).by(1)
+          .and change { event_rows.length }.by(1)
 
       expect(response).to have_http_status(:created)
       expect(json).to include(
@@ -822,6 +845,14 @@ RSpec.describe 'Materials API', type: :request do
         'drive_path' => '伊地知ニジカ/危険素材',
         'normalized_source_key' => 'google_drive_path_prefix:伊地知ニジカ/危険素材'
       )
+      event = event_rows.last
+      expect(event).to include(
+          'event_type' => 'materials.block', 'created_by_user_id' => member_user.id)
+      expect(materials.map { _1.reload.discarded? }).to eq([true, true])
+      versions = MaterialVersion.where(material_id: materials.map(&:id))
+      expect(versions.where(event_type: 'discard').pluck(:material_id))
+          .to match_array(materials.map(&:id))
+      expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
     end
   end
 
@@ -860,11 +891,19 @@ RSpec.describe 'Materials API', type: :request do
       end
 
       it 'discards the material and returns 204' do
-        delete "/materials/#{ material.id }"
+        expect { delete "/materials/#{ material.id }" }
+            .to change { event_rows.length }.by(1)
 
         expect(response).to have_http_status(:no_content)
         expect(Material.find_by(id: material.id)).to be_nil
         expect(Material.with_discarded.find(material.id)).to be_discarded
+        event = event_rows.last
+        expect(event).to include(
+            'event_type' => 'materials.destroy',
+            'created_by_user_id' => member_user.id)
+        versions = MaterialVersion.where(material_id: material.id)
+        expect(versions.order(:version_no).last.event_type).to eq('discard')
+        expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
       end
     end
   end

backend/spec/requests/nico_tags_spec.rb

@@ -177,6 +177,7 @@ RSpec.describe 'NicoTags', type: :request do
         }
       }.to change(TagVersion, :count).by(2)
        .and change(NicoTagVersion, :count).by(1)
+       .and change { event_rows.length }.by(1)
 
       expect(response).to have_http_status(:ok)
 
@@ -186,6 +187,10 @@ RSpec.describe 'NicoTags', type: :request do
       linked_versions = TagVersion.where(tag: [linked_a, linked_b]).order(:tag_id)
       expect(linked_versions.map(&:event_type)).to eq(['create', 'create'])
       expect(linked_versions.map(&:created_by_user_id)).to all(eq(admin.id))
+      event = event_rows.last
+      expect(event).to include(
+          'event_type' => 'tags.update', 'created_by_user_id' => admin.id)
+      expect(linked_versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
 
       versions = nico_tag.reload.nico_tag_versions.order(:version_no)
       expect(versions.map(&:event_type)).to eq(['create', 'update'])

backend/spec/requests/post_history_privacy_spec.rb

@@ -1,129 +0,0 @@
-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/posts_spec.rb

@@ -50,6 +50,8 @@ RSpec.describe 'Posts API', type: :request do
             post:,
             version_no: 1,
             event_type: 'create',
+            event_id: create_event!(
+                event_type: 'posts.create', created_by_user: post.uploaded_user).id,
             title: post.title,
             url: post.url,
             thumbnail_base: post.thumbnail_base,
@@ -629,37 +631,6 @@ 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 }" }
@@ -689,16 +660,6 @@ 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
@@ -1068,7 +1029,7 @@ RSpec.describe 'Posts API', type: :request do
 
     it 'dry-runs without persisting posts or new tags' do
       sign_in_as(member)
-      counts = [Post.count, Tag.count, TagName.count]
+      counts = [Post.count, Tag.count, TagName.count, event_rows.length]
 
       post '/posts?dry=1', params: post_write_params(
           title: 'dry-run post',
@@ -1084,7 +1045,7 @@ RSpec.describe 'Posts API', type: :request do
           [{ 'name' => 'new_dry_run_tag',
              'category' => 'character',
              'section_literals' => [] }])
-      expect([Post.count, Tag.count, TagName.count]).to eq(counts)
+      expect([Post.count, Tag.count, TagName.count, event_rows.length]).to eq(counts)
     end
 
     it 'dry-runs an existing URL without validating its upload' do
@@ -2259,20 +2220,20 @@ RSpec.describe 'Posts API', type: :request do
 
     def create_post_version! post, version_no:, event_type:, created_by_user:, created_at:
       PostVersion.create!(
-        post:,
-        version_no:,
-        event_type:,
-        title: post.title,
-        url: post.url,
-        thumbnail_base: post.thumbnail_base,
-        tags: snapshot_tags(post),
-        tags_json: post.snapshot_tags_json,
-        parent_post_ids: post.snapshot_parent_post_ids.join(' '),
-        original_created_from: post.original_created_from,
-        original_created_before: post.original_created_before,
-        created_at:,
-        created_by_user:
-      )
+          event_id: create_event!(event_type: 'unknown').id,
+          post:,
+          version_no:,
+          event_type:,
+          title: post.title,
+          url: post.url,
+          thumbnail_base: post.thumbnail_base,
+          tags: snapshot_tags(post),
+          tags_json: post.snapshot_tags_json,
+          parent_post_ids: post.snapshot_parent_post_ids.join(' '),
+          original_created_from: post.original_created_from,
+          original_created_before: post.original_created_before,
+          created_at:,
+          created_by_user:)
     end
 
     let!(:v1) do
@@ -2600,6 +2561,7 @@ RSpec.describe 'Posts API', type: :request do
             tags: 'spec_tag',
             thumbnail: dummy_upload)
       end.to change(PostVersion, :count).by(1)
+          .and change { event_rows.length }.by(1)
 
       expect(response).to have_http_status(:created)
 
@@ -2611,6 +2573,13 @@ RSpec.describe 'Posts API', type: :request do
       expect(version.url).to eq('https://example.com/versioned-post')
       expect(version.created_by_user_id).to eq(member.id)
       expect(version.tags).to eq(snapshot_tags(created_post))
+      event = event_rows.last
+      expect(event).to include(
+          'event_type' => 'posts.create', 'created_by_user_id' => member.id)
+      expect(version.event_id).to eq(event.fetch('id'))
+      tag_versions = TagVersion.where(tag_id: created_post.tags.select(:id))
+      expect(tag_versions).not_to be_empty
+      expect(tag_versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
     end
 
     it 'creates next version on PUT /posts/:id when snapshot changes' do
@@ -2626,6 +2595,7 @@ RSpec.describe 'Posts API', type: :request do
             title: 'updated title',
             tags: 'spec_tag_2')
       end.to change(PostVersion, :count).by(1)
+          .and change { event_rows.length }.by(1)
 
       expect(response).to have_http_status(:ok)
 
@@ -2635,6 +2605,12 @@ RSpec.describe 'Posts API', type: :request do
       expect(version.title).to eq('updated title')
       expect(version.created_by_user_id).to eq(member.id)
       expect(version.tags).to eq(snapshot_tags(post_record.reload))
+      event = event_rows.last
+      expect(event).to include(
+          'event_type' => 'posts.update', 'created_by_user_id' => member.id)
+      expect(version.event_id).to eq(event.fetch('id'))
+      tag_version = TagVersion.find_by!(tag_id: tag_name2.reload.tag_id, version_no: 1)
+      expect(tag_version.event_id).to eq(event.fetch('id'))
     end
 
     it 'does not create a new version on PUT /posts/:id when snapshot is unchanged' do
@@ -2643,6 +2619,7 @@ RSpec.describe 'Posts API', type: :request do
       PostTag.create!(post: post_record, tag: Tag.no_deerjikist)
       base_version = create_post_version_for!(post_record.reload)
 
+      events = event_rows
       expect {
         put "/posts/#{post_record.id}", params: post_write_params(
             base_version_no: base_version.version_no,
@@ -2656,10 +2633,12 @@ RSpec.describe 'Posts API', type: :request do
       expect(version.version_no).to eq(1)
       expect(version.event_type).to eq('create')
       expect(version.tags).to eq(snapshot_tags(post_record))
+      expect(event_rows).to eq(events)
     end
 
     it 'does not create a version when POST /posts is invalid' do
       sign_in_as(member)
+      events = event_rows
 
       expect do
         post '/posts', params: post_write_params(
@@ -2670,11 +2649,13 @@ RSpec.describe 'Posts API', type: :request do
       end.not_to change(PostVersion, :count)
 
       expect(response).to have_http_status(:unprocessable_entity)
+      expect(event_rows).to eq(events)
     end
 
     it 'does not create a version when PUT /posts/:id is invalid' do
       sign_in_as(member)
       base_version = create_post_version_for!(post_record)
+      events = event_rows
 
       expect do
         put "/posts/#{post_record.id}", params: post_write_params(
@@ -2686,6 +2667,7 @@ RSpec.describe 'Posts API', type: :request do
       end.not_to change(PostVersion, :count)
 
       expect(response).to have_http_status(:unprocessable_entity)
+      expect(event_rows).to eq(events)
     end
 
     it 'rejects second-bearing original created timestamps on POST /posts' do

backend/spec/requests/sitemap_entries_spec.rb

@@ -119,7 +119,9 @@ RSpec.describe 'Sitemap entries API', type: :request do
       # Legacy empty bodies can exist even though the write service rejects them.
       empty = TagDescription.create!(tag: empty_tag, language_code: 'ain',
                                      body: '', version_no: 1)
-      TagDescriptionVersion.create!(tag_id: empty_tag.id, language_code: 'ain',
+      TagDescriptionVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          tag_id: empty_tag.id, language_code: 'ain',
                                     body: '', version_no: 1, event_type: 'create',
                                     created_by_user_id: user.id, created_at: Time.current)
 

backend/spec/requests/tag_children_spec.rb

@@ -53,8 +53,13 @@ RSpec.describe "TagChildren", type: :request do
         expect { do_request }
           .to change { parent.reload.children.ids.include?(child.id) }
           .from(false).to(true)
+          .and change { event_rows.length }.by(1)
 
         expect(response).to have_http_status(:no_content)
+        event = event_rows.last
+        expect(event).to include(
+            'event_type' => 'tags.update', 'created_by_user_id' => admin.id)
+        expect(child.tag_versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
       end
 
       it 'returns 422 and does not create relation when the new link makes a cycle' do
@@ -132,6 +137,7 @@ RSpec.describe "TagChildren", type: :request do
         expect {
           do_request
         }.to change(TagVersion, :count).by(2)
+            .and change { event_rows.length }.by(1)
 
         expect(response).to have_http_status(:no_content)
 
@@ -140,6 +146,10 @@ RSpec.describe "TagChildren", type: :request do
         expect(versions.first.parent_tag_ids.split).to include(parent.id.to_s)
         expect(versions.second.parent_tag_ids).to eq('')
         expect(versions.second.created_by_user_id).to eq(admin.id)
+        event = event_rows.last
+        expect(event).to include(
+            'event_type' => 'tags.update', 'created_by_user_id' => admin.id)
+        expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
       end
     end
 

backend/spec/requests/tag_description_wiki_spec.rb

@@ -8,6 +8,7 @@ RSpec.describe 'Tag description Wiki compatibility', type: :request do
   let!(:versions) do
     ['A', 'A', 'new-version'].each_with_index.map do |body, index|
       TagDescriptionVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
           tag_id: tag.id, language_code: 'ja', version_no: index + 1,
           event_type: index.zero? ? 'create' : 'update', body:,
           created_by_user_id: user.id, created_at: Time.current)
@@ -73,6 +74,7 @@ RSpec.describe 'Tag description Wiki compatibility', type: :request do
     let!(:other_tag) { create(:tag, primary_name: 'other_description_contract') }
     let!(:other_version) do
       TagDescriptionVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
           tag_id: other_tag.id, language_code: 'ja', version_no: 1,
           event_type: 'create', body: 'other tag history',
           created_by_user_id: user.id, created_at: Time.current)

backend/spec/requests/tag_descriptions_spec.rb

@@ -13,7 +13,7 @@ RSpec.describe 'Tag description native API', type: :request do
   def stored_state
     [TagDescription, TagDescriptionVersion, TagName, TagVersion].map do |model|
       model.order(:id).map(&:attributes)
-    end
+    end + [event_rows]
   end
 
   def fail_save model
@@ -91,6 +91,8 @@ RSpec.describe 'Tag description native API', type: :request do
     let!(:version) do
       TagDescriptionVersion.create!(
           tag_id: tag.id, language_code: 'ja', body: 'native version', version_no: 1,
+          event_id: create_event!(
+              event_type: 'tag_descriptions.create', created_by_user: author).id,
           event_type: 'create', created_by_user_id: author.id, created_at: Time.current)
     end
     let(:name_endpoint) { "/tags/name/#{ tag_name.name }/description" }
@@ -185,6 +187,7 @@ RSpec.describe 'Tag description native API', type: :request do
         expect { native_write(body: 'created natively') }
             .to change(TagDescription, :count).by(1)
             .and change(TagDescriptionVersion, :count).by(1)
+            .and change { event_rows.length }.by(1)
         expect(response).to have_http_status(:created)
         description = TagDescription.find_by!(tag_id: tag.id, language_code: 'ja')
         expect_current(description)
@@ -192,6 +195,10 @@ RSpec.describe 'Tag description native API', type: :request do
         expect(version).to have_attributes(
             body: 'created natively', version_no: 1, event_type: 'create',
             created_by_user_id: editor.id)
+        event = event_rows.last
+        expect(event).to include(
+            'event_type' => 'tag_descriptions.create', 'created_by_user_id' => editor.id)
+        expect(version.event_id).to eq(event.fetch('id'))
         get "/wiki/#{ description.id }"
         expect(response).to have_http_status(:ok)
         expect(json).to include('body' => description.body, 'revision_id' => version.id)
@@ -223,6 +230,7 @@ RSpec.describe 'Tag description native API', type: :request do
         expect(description.version_no).to eq(1)
         expect { native_write(body: 'after') }
             .to change(TagDescriptionVersion, :count).by(1)
+            .and change { event_rows.length }.by(1)
         expect(response).to have_http_status(:ok)
         expect(description.reload).to have_attributes(
             body: 'after', version_no: 2,
@@ -234,6 +242,10 @@ RSpec.describe 'Tag description native API', type: :request do
         expect(version).to have_attributes(
             tag_id: tag.id, language_code: 'ja', version_no: 2, event_type: 'update',
             body: 'after', created_by_user_id: editor.id)
+        event = event_rows.last
+        expect(event).to include(
+            'event_type' => 'tag_descriptions.update', 'created_by_user_id' => editor.id)
+        expect(version.event_id).to eq(event.fetch('id'))
         expect(revision.body).to eq(version.body)
         expect(description_versions(page).order(:version_no).last.body).to eq(version.body)
         get "/wiki/#{ description.id }"

backend/spec/requests/tag_groups_spec.rb

@@ -121,10 +121,14 @@ RSpec.describe 'Tag group native API', type: :request do
     [:create, :update].each do |operation|
       it "#{ operation }s structured data and keeps unplaced membership" do
         previous = group_version(group_id, 1)
-        native_write(operation)
+        expect { native_write(operation) }.to change { event_rows.length }.by(1)
         expect(response).to have_http_status(operation == :create ? :created : :ok)
         id = operation == :create ? json.fetch('id') : group_id
         number = operation == :create ? 1 : 2
+        event = event_rows.last
+        event_type = operation == :create ? 'tag_groups.create' : 'tag_groups.update'
+        expect(event).to include('event_type' => event_type, 'created_by_user_id' => user.id)
+        expect(group_version(id, number).fetch('event_id')).to eq(event.fetch('id'))
         expect_group_snapshot(
             id, number:, members: snapshot_members, placements:, description: '全体の説明')
         expect(group_version(group_id, 1)).to eq(previous)

backend/spec/requests/tag_versions_spec.rb

@@ -30,6 +30,7 @@ RSpec.describe 'TagVersions API', type: :request do
   )
     version =
         TagVersion.create!(
+            event_id: create_event!(event_type: 'unknown').id,
             tag: tag,
             version_no: version_no,
             event_type: event_type,

backend/spec/requests/tags_spec.rb

@@ -705,6 +705,7 @@ RSpec.describe 'Tags API', type: :request do
         expect {
           patch "/tags/#{tag.id}", params: { name: 'new_tag_name', category: 'meme' }
         }.to change(TagVersion, :count).by(2)
+            .and change { event_rows.length }.by(1)
 
         expect(response).to have_http_status(:ok)
 
@@ -719,6 +720,10 @@ RSpec.describe 'Tags API', type: :request do
         expect(version_primary_name(versions.second, 'ja')).to eq('new_tag_name')
         expect(versions.second.category).to eq('meme')
         expect(versions.second.created_by_user_id).to eq(member_user.id)
+        event = event_rows.last
+        expect(event).to include(
+            'event_type' => 'tags.update', 'created_by_user_id' => member_user.id)
+        expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
       end
 
       it 'updates deprecated state and records it in tag versions' do
@@ -1275,6 +1280,7 @@ RSpec.describe 'Tags API', type: :request do
             deprecated: '0',
           }
         }.to change(TagVersion, :count).by(2)
+            .and change { event_rows.length }.by(1)
 
         expect(response).to have_http_status(:ok)
 
@@ -1290,6 +1296,10 @@ RSpec.describe 'Tags API', type: :request do
         expect(versions.second.category).to eq('meta')
         expect(version_alias_names(versions.second, 'ja')).to include('spec_tag')
         expect(versions.second.created_by_user_id).to eq(member_user.id)
+        event = event_rows.last
+        expect(event).to include(
+            'event_type' => 'tags.update', 'created_by_user_id' => member_user.id)
+        expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
       end
 
       it '同じ tag の旧 alias へ戻しても rename できる' do

backend/spec/services/counts_export_spec.rb

@@ -143,7 +143,9 @@ RSpec.describe 'Counts export contracts' do
     expect(CountsExportDownload.find(token, 'owner')).not_to be_nil
     expect(CountsExportDownload.find(token, 'other')).to be_nil
     post = create(:post)
-    PostVersion.create!(post:, version_no: 1, event_type: 'discard', url: post.url,
+    PostVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        post:, version_no: 1, event_type: 'discard', url: post.url,
         title: 'private', tags: '', tags_json: [], parent_post_ids: '', created_at: Time.utc(2024))
     expect(CountsExportDownload.find(token, 'owner')).to be_nil
   end
@@ -221,15 +223,9 @@ RSpec.describe CountsExportDownload::ResponseBody do
       body = described_class.new(source) { |state| states << state; true }
       response = ActionDispatch::Response.new
       response.body = body
-
-      _, _, rack_body = response.to_a
-
+      deferred = response.stream.to_ary
       expect(states).to eq([])
-
-      chunks = []
-      rack_body.each { |chunk| chunks << chunk }
-
-      expect(chunks.join).to eq(payload)
+      expect(deferred.to_a.join).to eq(payload)
       expect(states.count('started')).to eq(1)
     end
   end

backend/spec/services/counts_pivot_security_spec.rb

@@ -13,7 +13,9 @@ RSpec.describe 'Counts masked pivot contracts' do
   let!(:tags) do
     ['A', 'B', 'C'].map do |name|
       tag = create(:tag, primary_name: name)
-      TagVersion.create!(tag:, version_no: 1, event_type: 'create', name:,
+      TagVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          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))
@@ -25,12 +27,16 @@ RSpec.describe 'Counts masked pivot contracts' do
     [[0, 1], [0], [1, 2]].each_with_index do |indexes, index|
       post = create(:post)
       snapshot = indexes.map { { tag_id: tags[_1].id, version_no: 1, sections: [] } }
-      PostVersion.create!(post:, version_no: 1, event_type: 'create',
+      PostVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          post:, version_no: 1, event_type: 'create',
           title: "hidden-title-#{ index }", url: post.url, tags: '', tags_json: snapshot,
           parent_post_ids: '', created_by_user: member, created_at: Time.utc(2024, 1))
       next if index == 2
 
-      PostVersion.create!(post:, version_no: 2, event_type: 'discard',
+      PostVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          post:, version_no: 2, event_type: 'discard',
           title: "private-discard-#{ index }", url: post.url, tags: '', tags_json: [],
           parent_post_ids: '', created_by_user: member, created_at: Time.utc(2024, 2))
     end
@@ -98,12 +104,16 @@ RSpec.describe 'Counts masked pivot contracts' do
 
   it 'uses changed-record membership for totals and hides changes to private predecessors' do
     post = PostVersion.order(:id).last.post
-    PostVersion.create!(post:, version_no: 2, event_type: 'update', title: 'changed-public-title',
+    PostVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        post:, version_no: 2, event_type: 'update', title: 'changed-public-title',
         url: post.url, tags: '',
         tags_json: [{ tag_id: tags.last.id, version_no: 1, sections: [] }],
         parent_post_ids: '', created_at: Time.utc(2024, 3))
     restored = PostVersion.order(:id).first.post
-    PostVersion.create!(post: restored, version_no: 3, event_type: 'restore',
+    PostVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        post: restored, version_no: 3, event_type: 'restore',
         title: 'restored-public-title', url: restored.url, tags: '',
         tags_json: [{ tag_id: tags.first.id, version_no: 1, sections: [] }], parent_post_ids: '',
         created_at: Time.utc(2024, 4))
@@ -134,7 +144,9 @@ RSpec.describe 'Counts masked pivot contracts' do
 
   it 'keeps NULL as a public data value rather than treating it as a rollup' do
     post = create(:post)
-    PostVersion.create!(post:, version_no: 1, event_type: 'create', title: 'public bot',
+    PostVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
+        post:, version_no: 1, event_type: 'create', title: 'public bot',
         url: post.url, tags: '', tags_json: [], parent_post_ids: '', created_at: Time.utc(2024, 5))
     page = result(nil, 'rows' => 'user', 'cols' => 'event_type')
     expect(page[:cells].select { _1[:values].first.nil? }.sum { _1[:count] }).to eq(1)
@@ -145,7 +157,9 @@ RSpec.describe 'Counts masked pivot contracts' do
   it 'sorts public numeric values numerically alongside a masked group' do
     post = PostVersion.order(:id).last.post
     [2, 10].each do |number|
-      PostVersion.create!(post:, version_no: number, event_type: 'update',
+      PostVersion.create!(
+          event_id: create_event!(event_type: 'unknown').id,
+          post:, version_no: number, event_type: 'update',
           title: 'public numeric sort', url: post.url, tags: '', tags_json: [],
           parent_post_ids: '', created_at: Time.utc(2024, 5))
     end

backend/spec/services/material_sync_importer_spec.rb

@@ -56,6 +56,7 @@ RSpec.describe MaterialSyncImporter do
                                profile: 'legacy_drive',
                                export_path: '素材/a.png',
                                created_by_user: user)
+    events = event_rows
 
     result =
         described_class.import!(
@@ -73,6 +74,7 @@ RSpec.describe MaterialSyncImporter do
     expect(result.action).to eq(:unchanged)
     expect(material.reload.tag).to eq(tag)
     expect(material.url).to eq('https://example.com/human')
+    expect(event_rows).to eq(events)
   end
 
   it 'suppresses a Google Drive candidate by relative path prefix' do

backend/spec/services/material_sync_runner_spec.rb

@@ -14,6 +14,47 @@ RSpec.describe MaterialSyncRunner do
   let(:drive_client) { instance_double(GoogleDrive::ApiClient) }
 
   describe '#sync!' do
+    it 'groups created and updated materials across sync sources into one event' do
+      existing = Material.create!(
+          source_kind: 'google_drive_file', source_file_id: 'existing-file',
+          source_path: 'old.png', url: 'https://example.com/existing',
+          created_by_user: user, updated_by_user: user)
+      source
+      MaterialSyncSource.create!(
+          name: 'Second Drive source', source_kind: 'google_drive_path',
+          source_file_id: 'folder-456', profile: 'legacy_drive',
+          created_by_user: user, updated_by_user: user)
+      allow(GoogleDrive::ApiClient).to receive(:new).and_return(drive_client)
+      allow(drive_client).to receive(:each_material_file_under_folder) do |folder_id, &block|
+        id = folder_id == 'folder-123' ? 'existing-file' : 'new-file'
+        block.call(id:, name: "#{ id }.png", mime_type: 'image/png',
+                   relative_path: "素材/#{ id }.png", sha256_checksum: nil,
+                   web_view_link: "https://drive.google.com/file/d/#{ id }/view")
+      end
+      allow(drive_client).to receive(:download_to_tempfile) do |id, **|
+        Tempfile.new(['sync-event', '.png']).tap do |file|
+          file.binmode
+          file.write(id)
+          file.rewind
+        end
+      end
+      allow(MaterialThumbnailGenerator).to receive(:generate!)
+      previous_ids = MaterialVersion.pluck(:id)
+
+      result = nil
+      expect { result = described_class.sync_enabled! }
+          .to change { event_rows.length }.by(1)
+
+      expect(result).to have_attributes(imported: 1, updated: 1, failed: 0)
+      event = event_rows.last
+      expect(event.fetch('event_type')).to eq('materials.sync')
+      created = Material.find_by!(source_file_id: 'new-file')
+      versions = MaterialVersion.where.not(id: previous_ids)
+      expect(versions.pluck(:material_id).uniq).to contain_exactly(existing.id, created.id)
+      expect(versions.pluck(:event_type)).to include('create', 'update')
+      expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
+    end
+
     it 'imports google drive path candidates as they are yielded' do
       first_entry = { id: 'file-1',
                       name: 'a.png',

backend/spec/services/post_bulk_creator_spec.rb

@@ -88,3 +88,86 @@ RSpec.describe PostBulkCreator do
     expect(creator).to have_received(:create!).with(locale).once
   end
 end
+
+RSpec.describe 'PostBulkCreator event grouping', type: :model do
+  self.use_transactional_tests = false
+
+  before do
+    expect(Rails.env.test?).to be(true)
+    expect(ApplicationRecord.connection.open_transactions).to eq(0)
+    @prefix = "bulk_event_#{ SecureRandom.hex(8) }"
+    @actor = create(:user, :member)
+    allow(PostCreatePreflight).to receive(:new) do |attributes:, **|
+      specs = [{ name: attributes.fetch(:title), category: :general }]
+      instance_double(PostCreatePreflight, run: attributes.merge(
+          existing_post_id: nil, snapshot_tag_specs: specs, post_tag_specs: specs,
+          normalised_parent_post_ids: [], tag_sections: { }, video_ms: nil))
+    end
+  end
+
+  after do
+    if @actor
+      posts = Post.where(uploaded_user: @actor)
+      PostTagSection.where(post_id: posts.select(:id)).delete_all
+      PostTag.where(post_id: posts.select(:id)).delete_all
+      PostVersion.where(post_id: posts.select(:id)).delete_all
+      posts.delete_all
+      tag_ids = TagName.where(name: ["#{ @prefix }_1", "#{ @prefix }_2"]).pluck(:tag_id)
+      TagVersion.where(tag_id: tag_ids).delete_all
+      TagName.where(tag_id: tag_ids).delete_all
+      Tag.where(id: tag_ids).delete_all
+      EventRecords::EventRow.where(created_by_user_id: @actor.id).delete_all
+      @actor.delete
+    end
+  end
+
+  it 'shares one creation event between real workers and their tag histories' do
+    posts = [1, 2].map do |number|
+      { title: "#{ @prefix }_#{ number }",
+        url: "https://example.com/#{ @prefix }/#{ number }" }
+    end
+
+    result = nil
+    expect {
+      result = PostBulkCreator.new(actor: @actor, posts:, thumbnails: { })
+          .run(Locale.nipponese)
+    }.to change { event_rows.length }.by(1)
+
+    expect(result.fetch(:results).map { _1.fetch(:status) }).to eq(['created', 'created'])
+    event = event_rows.last
+    expect(event).to include(
+        'event_type' => 'posts.create', 'created_by_user_id' => @actor.id)
+    versions = PostVersion.where(created_by_user_id: @actor.id)
+    expect(versions.count).to eq(2)
+    expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
+    tag_versions = TagVersion.where(created_by_user_id: @actor.id)
+    expect(tag_versions.count).to eq(2)
+    expect(tag_versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
+  end
+
+  it 'does not leave an event when every row fails validation' do
+    preflight = instance_double(PostCreatePreflight)
+    allow(PostCreatePreflight).to receive(:new).and_return(preflight)
+    allow(preflight).to receive(:run).and_raise(
+        PostCreatePreflight::ValidationFailed.new(fields: { url: ['invalid'] }))
+    events = event_rows
+
+    result = PostBulkCreator.new(
+        actor: @actor, posts: [{ title: 'invalid' }], thumbnails: { }).run(Locale.nipponese)
+
+    expect(result.fetch(:results).map { _1.fetch(:status) }).to eq(['failed'])
+    expect(event_rows).to eq(events)
+  end
+
+  it 'does not leave an event when every row is skipped' do
+    preflight = instance_double(PostCreatePreflight, run: { existing_post_id: 123 })
+    allow(PostCreatePreflight).to receive(:new).and_return(preflight)
+    events = event_rows
+
+    result = PostBulkCreator.new(
+        actor: @actor, posts: [{ title: 'existing' }], thumbnails: { }).run(Locale.nipponese)
+
+    expect(result.fetch(:results).map { _1.fetch(:status) }).to eq(['skipped'])
+    expect(event_rows).to eq(events)
+  end
+end

backend/spec/services/shared_resource_id_allocator_mysql_spec.rb

@@ -16,6 +16,7 @@ RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
     @tag = create(:tag, primary_name: "#{ @prefix }_owner")
     @group = TagGroup.create!(name: "#{ @prefix }_owner", version_no: 1)
     @tag_ids = Queue.new
+    @event_ids = Queue.new
     @threads = []
     @release = Queue.new
   end
@@ -42,6 +43,9 @@ RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
       ids << @tag.id if @tag
       TagName.where(tag_id: ids).delete_all
       Tag.where(id: ids).delete_all
+      event_ids = []
+      event_ids << @event_ids.pop until @event_ids.empty? if @event_ids
+      EventRecords::EventRow.where(id: event_ids).delete_all
     end
   end
 
@@ -72,11 +76,17 @@ RSpec.describe 'Shared resource IDs across MySQL connections', type: :model do
     when :description
       TagDescription.create!(tag: @tag, language_code: 'ja', body: '', version_no: 1)
     when :description_version
+      event = create_event!(event_type: 'unknown')
+      @event_ids << event.id
       TagDescriptionVersion.create!(
+          event_id: event.id,
           tag_id: @tag.id, language_code: 'ja', body: 'body', version_no: 1,
           event_type: 'create', created_at: Time.current)
     when :group_version
+      event = create_event!(event_type: 'unknown')
+      @event_ids << event.id
       TagGroupVersion.create!(
+          event_id: event.id,
           tag_group: @group, name: @group.name, version_no: 1, event_type: 'create',
           members: [], placements: [], created_at: Time.current)
     when :group

backend/spec/services/shared_resource_id_allocator_spec.rb

@@ -15,10 +15,12 @@ RSpec.describe SharedResourceIdAllocator do
       TagGroup.new(id:, name: "group #{ number }", version_no: number)
     when 'tag_description_versions'
       TagDescriptionVersion.new(
+          event_id: create_event!(event_type: 'unknown').id,
           id:, tag_id: tag.id, language_code: 'ja', body: 'body', version_no: number,
           event_type: 'create', created_at: Time.current)
     when 'tag_group_versions'
       TagGroupVersion.new(
+          event_id: create_event!(event_type: 'unknown').id,
           id:, tag_group_id: group.id, name: group.name, version_no: number,
           event_type: 'create', members: [], placements: [], created_at: Time.current)
     end
@@ -82,6 +84,7 @@ RSpec.describe SharedResourceIdAllocator do
   it 'reserves a Tag ID referenced only by remaining description history' do
     high = [Tag.maximum(:id).to_i, ExternalTag.maximum(:id).to_i].max + 1000
     TagDescriptionVersion.create!(
+        event_id: create_event!(event_type: 'unknown').id,
         tag_id: high, language_code: 'ja', version_no: 1, body: 'history',
         event_type: 'create', created_at: Time.current)
     expect(create(:tag).id).to be > high

backend/spec/services/youtube/sync_spec.rb

@@ -42,6 +42,41 @@ RSpec.describe Youtube::Sync do
   end
 
   describe '#sync!' do
+    it 'groups created and updated post histories into one sync event' do
+      allow(PostVersionRecorder).to receive(:record!).and_call_original
+      allow(PostVersionRecorder).to receive(:ensure_snapshot!).and_call_original
+      existing = create(:post, url: 'https://youtu.be/video-1', title: 'old title')
+      allow(sync).to receive(:query_terms).and_return([])
+      allow(sync).to receive(:playlist_ids).and_return(['PL123'])
+      allow(client).to receive(:playlist_items).with(playlist_id: 'PL123', page_token: nil)
+          .and_return('items' => [
+              { 'contentDetails' => { 'videoId' => 'video-1' } },
+              { 'contentDetails' => { 'videoId' => 'video-2' } }])
+      allow(client).to receive(:videos).with(['video-1', 'video-2'])
+          .and_return('items' => [
+              youtube_video_item(id: 'video-1', title: 'updated', channel_id: 'UC_NONE'),
+              youtube_video_item(id: 'video-2', title: 'created', channel_id: 'UC_NONE')])
+      previous_post_ids = PostVersion.pluck(:id)
+      previous_tag_ids = TagVersion.pluck(:id)
+
+      expect { sync.sync! }.to change { event_rows.length }.by(1)
+
+      event = event_rows.last
+      expect(event).to include('event_type' => 'posts.sync', 'created_by_user_id' => nil)
+      versions = PostVersion.where.not(id: previous_post_ids)
+      created = Post.find_by!(url: 'https://www.youtube.com/watch?v=video-2')
+      expect(versions.pluck(:post_id).uniq).to contain_exactly(existing.id, created.id)
+      expect(versions.pluck(:event_type)).to include('create', 'update')
+      expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
+      tag_versions = TagVersion.where.not(id: previous_tag_ids)
+      expect(tag_versions).not_to be_empty
+      expect(tag_versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
+
+      events = event_rows
+      expect { sync.sync! }.not_to change(PostVersion, :count)
+      expect(event_rows).to eq(events)
+    end
+
     it 'returns without fetching video details when no video ids are discovered' do
       allow(sync).to receive(:query_terms).and_return([])
       allow(sync).to receive(:playlist_ids).and_return([])

backend/spec/support/event_records.rb

@@ -0,0 +1,15 @@
+module EventRecords
+  # Read the database contract without requiring an application Event model.
+  class EventRow < ActiveRecord::Base
+    self.table_name = 'events'
+  end
+
+  def event_rows
+    EventRow.order(:id).map(&:attributes)
+  end
+
+  def create_event! event_type:, created_by_user: nil
+    EventRow.create!(event_type:, created_by_user_id: created_by_user&.id,
+                     created_at: Time.current)
+  end
+end

backend/spec/support/tag_group_records.rb

@@ -3,11 +3,13 @@ require 'cgi'
 # SQL fixtures use the migration contract without inventing application models.
 # Include explicitly; these helpers must not affect unrelated examples.
 module TagGroupRecords
+  include EventRecords
+
   GROUP_TABLES = [
       'tag_groups', 'tag_group_tags', 'tag_group_groups',
       'tag_group_placements', 'tag_group_versions'].freeze
   WRITE_TABLES = GROUP_TABLES + [
-      'tag_names', 'tag_description_versions',
+      'events', 'tag_names', 'tag_description_versions',
       'tag_descriptions']
 
   def group_connection = ApplicationRecord.connection
@@ -114,6 +116,7 @@ module TagGroupRecords
     group_id = insert_group_row('tag_groups', attributes)
     insert_group_row('tag_group_versions', {
         tag_group_id: group_id, version_no: 1, event_type: 'create',
+        event_id: create_event!(event_type: 'tag_groups.create', created_by_user: user).id,
         name:, description:, members: members.to_json, placements: placements.to_json,
         created_by_user_id: user.id, created_at: now })
     members.each do |member|

backend/spec/tasks/nico_sync_spec.rb

@@ -174,20 +174,20 @@ RSpec.describe 'nico:sync' do
 
   def create_post_version_for!(post, version_no: 1, event_type: 'create', created_by_user: nil)
     PostVersion.create!(
-      post: post,
-      version_no: version_no,
-      event_type: event_type,
-      title: post.title,
-      url: post.url,
-      thumbnail_base: post.thumbnail_base,
-      tags: snapshot_tags(post),
-      tags_json: post.snapshot_tags_json,
-      parent_post_ids: post.snapshot_parent_post_ids.join(' '),
-      original_created_from: post.original_created_from,
-      original_created_before: post.original_created_before,
-      created_at: Time.current,
-      created_by_user: created_by_user
-    )
+        event_id: create_event!(event_type: 'unknown').id,
+        post: post,
+        version_no: version_no,
+        event_type: event_type,
+        title: post.title,
+        url: post.url,
+        thumbnail_base: post.thumbnail_base,
+        tags: snapshot_tags(post),
+        tags_json: post.snapshot_tags_json,
+        parent_post_ids: post.snapshot_parent_post_ids.join(' '),
+        original_created_from: post.original_created_from,
+        original_created_before: post.original_created_before,
+        created_at: Time.current,
+        created_by_user: created_by_user)
   end
 
   it '新規 post 作成時に version 1 を作る' do
@@ -209,6 +209,7 @@ RSpec.describe 'nico:sync' do
     expect {
       run_rake_task('nico:sync')
     }.to change(PostVersion, :count).by(1)
+        .and change { event_rows.length }.by(1)
 
     post = Post.find_by!(url: 'https://www.nicovideo.jp/watch/sm9')
     version = post.post_versions.order(:version_no).last
@@ -217,6 +218,32 @@ RSpec.describe 'nico:sync' do
     expect(version.event_type).to eq('create')
     expect(version.created_by_user).to be_nil
     expect(version.tags).to eq(snapshot_tags(post.reload))
+    event = event_rows.last
+    expect(event).to include('event_type' => 'posts.sync', 'created_by_user_id' => nil)
+    expect(version.event_id).to eq(event.fetch('id'))
+  end
+
+  it 'groups created and updated post histories into one sync event' do
+    existing = create(:post, title: 'old', url: 'https://www.nicovideo.jp/watch/sm9')
+    stub_python([
+        { 'code' => 'sm9', 'title' => 'updated', 'tags' => [] },
+        { 'code' => 'sm10', 'title' => 'created', 'tags' => [] }])
+    allow(URI).to receive(:open).and_return(StringIO.new('<html></html>'))
+    previous_post_ids = PostVersion.pluck(:id)
+    previous_tag_ids = TagVersion.pluck(:id)
+
+    expect { run_rake_task('nico:sync') }.to change { event_rows.length }.by(1)
+
+    event = event_rows.last
+    expect(event).to include('event_type' => 'posts.sync', 'created_by_user_id' => nil)
+    created = Post.find_by!(url: 'https://www.nicovideo.jp/watch/sm10')
+    versions = PostVersion.where.not(id: previous_post_ids)
+    expect(versions.pluck(:post_id).uniq).to contain_exactly(existing.id, created.id)
+    expect(versions.pluck(:event_type)).to include('create', 'update')
+    expect(versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
+    tag_versions = TagVersion.where.not(id: previous_tag_ids)
+    expect(tag_versions).not_to be_empty
+    expect(tag_versions.pluck(:event_id).uniq).to eq([event.fetch('id')])
   end
 
   it '既存 post の内容または tags が変わったとき update version を作る' do
@@ -282,6 +309,7 @@ RSpec.describe 'nico:sync' do
     }])
 
     allow(URI).to receive(:open).and_return(StringIO.new('<html></html>'))
+    events = event_rows
 
     expect {
       run_rake_task('nico:sync')
@@ -291,6 +319,7 @@ RSpec.describe 'nico:sync' do
     expect(version.version_no).to eq(1)
     expect(version.event_type).to eq('create')
     expect(version.tags).to eq(snapshot_tags(post.reload))
+    expect(event_rows).to eq(events)
   end
 
   it '新規 nico tag に nico tag version を作る' do

frontend/public/fonts/noto-sans-mongolian/LICENSE

@@ -1,94 +0,0 @@
-Copyright 2018 The Noto Project Authors (github.com/googlei18n/noto-fonts)
-
-This Font Software is licensed under the SIL Open Font License,
-Version 1.1.
-
-This license is copied below, and is also available with a FAQ at:
-http://scripts.sil.org/OFL
-
------------------------------------------------------------
-SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
------------------------------------------------------------
-
-PREAMBLE
-The goals of the Open Font License (OFL) are to stimulate worldwide
-development of collaborative font projects, to support the font
-creation efforts of academic and linguistic communities, and to
-provide a free and open framework in which fonts may be shared and
-improved in partnership with others.
-
-The OFL allows the licensed fonts to be used, studied, modified and
-redistributed freely as long as they are not sold by themselves. The
-fonts, including any derivative works, can be bundled, embedded,
-redistributed and/or sold with any software provided that any reserved
-names are not used by derivative works. The fonts and derivatives,
-however, cannot be released under any other type of license. The
-requirement for fonts to remain under this license does not apply to
-any document created using the fonts or their derivatives.
-
-DEFINITIONS
-"Font Software" refers to the set of files released by the Copyright
-Holder(s) under this license and clearly marked as such. This may
-include source files, build scripts and documentation.
-
-"Reserved Font Name" refers to any names specified as such after the
-copyright statement(s).
-
-"Original Version" refers to the collection of Font Software
-components as distributed by the Copyright Holder(s).
-
-"Modified Version" refers to any derivative made by adding to,
-deleting, or substituting -- in part or in whole -- any of the
-components of the Original Version, by changing formats or by porting
-the Font Software to a new environment.
-
-"Author" refers to any designer, engineer, programmer, technical
-writer or other person who contributed to the Font Software.
-
-PERMISSION & CONDITIONS
-Permission is hereby granted, free of charge, to any person obtaining
-a copy of the Font Software, to use, study, copy, merge, embed,
-modify, redistribute, and sell modified and unmodified copies of the
-Font Software, subject to the following conditions:
-
-1) Neither the Font Software nor any of its individual components, in
-Original or Modified Versions, may be sold by itself.
-
-2) Original or Modified Versions of the Font Software may be bundled,
-redistributed and/or sold with any software, provided that each copy
-contains the above copyright notice and this license. These can be
-included either as stand-alone text files, human-readable headers or
-in the appropriate machine-readable metadata fields within text or
-binary files as long as those fields can be easily viewed by the user.
-
-3) No Modified Version of the Font Software may use the Reserved Font
-Name(s) unless explicit written permission is granted by the
-corresponding Copyright Holder. This restriction only applies to the
-primary font name as presented to the users.
-
-4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
-Software shall not be used to promote, endorse or advertise any
-Modified Version, except to acknowledge the contribution(s) of the
-Copyright Holder(s) and the Author(s) or with their explicit written
-permission.
-
-5) The Font Software, modified or unmodified, in part or in whole,
-must be distributed entirely under this license, and must not be
-distributed under any other license. The requirement for fonts to
-remain under this license does not apply to any document created using
-the Font Software.
-
-TERMINATION
-This license becomes null and void if any of the above conditions are
-not met.
-
-DISCLAIMER
-THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
-MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
-OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
-COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
-INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
-DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
-OTHER DEALINGS IN THE FONT SOFTWARE.

frontend/public/fonts/noto-sans-mongolian/SOURCE.md

@@ -1,11 +0,0 @@
-Noto Sans Mongolian Regular, unmodified TrueType font.
-
-Font copyright: Copyright 2018 Google Inc. All Rights Reserved.
-
-- Source: https://github.com/notofonts/noto-fonts/tree/main/hinted/ttf/NotoSansMongolian
-- Font: https://raw.githubusercontent.com/notofonts/noto-fonts/main/hinted/ttf/NotoSansMongolian/NotoSansMongolian-Regular.ttf
-- License: SIL Open Font License 1.1; see the accompanying LICENSE.
-- Retrieved: 2026-11-08.
-
-Used only by the Unicode Mongolian sample in the development layout route.
-The font and license are served together from this directory.

frontend/src/App.tsx

@@ -20,13 +20,13 @@ import { Toaster } from '@/components/ui/toaster'
 import { isApiError } from '@/lib/api'
 import { initialiseUserSession } from '@/lib/users'
 import { prepareHelpPage } from '@/lib/help'
-import { fetchLocales, isLocaleCode, isVerticalPreviewPath, legacyLocalePath,
-	 localiseTo, switchLocalePath, unlocalisedPath } from '@/lib/locales'
+import { fetchLocales, isLocaleCode, legacyLocalePath,
+	 switchLocalePath, unlocalisedPath } from '@/lib/locales'
 import { isAuthorityDependentQuery, localesKeys, sessionKeys } from '@/lib/queryKeys'
 import { isCountsPath } from '@/lib/routeLocales'
 import { switchPostFilterLocale } from '@/lib/posts'
 import { switchWikiLocale } from '@/lib/wiki'
-import { useLocale, useVerticalPreview } from '@/lib/useLocale'
+import { useLocale } from '@/lib/useLocale'
 import { applyClientAnimationMode,
 	 applyClientAppearance,
 	 fetchUserThemeSlots,
@@ -267,7 +267,6 @@ const RoutedApp = ({ locales }: { locales: AvailableLocale[] }) => {
   const client = useQueryClient ()
   const location = useLocation ()
   const locale = useLocale ()
-  const verticalPreview = useVerticalPreview ()
   const route = resolvePageRoute (location.pathname)
   const robots = isCountsPath (location.pathname) ? 'noindex' : route?.route.handle?.robots
   const pagePath = unlocalisedPath (location.pathname)
@@ -394,8 +393,7 @@ const RoutedApp = ({ locales }: { locales: AvailableLocale[] }) => {
 	      <motion.div
 		  layout={(animationMode === 'off' || countsPage) ? false : 'position'}
 		  transition={{ layout: appLayoutTransition }}
-		  data-vertical-preview={verticalPreview || undefined}
-		  className="app-layout relative flex h-dvh w-full flex-col overflow-y-hidden">
+		  className="relative flex h-dvh w-full flex-col overflow-y-hidden">
 		<TopNav user={user} locales={locales} resolveLocaleSwitch={switchLocale}/>
 		<RouteTransitionWrapper
 		    user={user}
@@ -414,7 +412,6 @@ const RoutedApp = ({ locales }: { locales: AvailableLocale[] }) => {
 const LocaleRoute: FC = () => {
   const { locale } = useParams ()
   const location = useLocation ()
-  const verticalPreview = isVerticalPreviewPath (location.pathname)
   const { i18n } = useTranslation ()
   const { data, isError } = useQuery ({
       queryKey: localesKeys.index,
@@ -424,11 +421,10 @@ const LocaleRoute: FC = () => {
       refetchOnMount: true,
       refetchOnWindowFocus: true,
       refetchOnReconnect: true })
-  const contentLocale = verticalPreview ? 'ja' : locale
   const activeLocale =
-      (isLocaleCode (contentLocale)
-       && data?.locales.some (entry => entry.code === contentLocale))
-      ? contentLocale
+      (isLocaleCode (locale)
+       && data?.locales.some (entry => entry.code === locale))
+      ? locale
       : null
 
   useLayoutEffect (() => {
@@ -439,15 +435,15 @@ const LocaleRoute: FC = () => {
   }, [activeLocale, i18n])
 
   const redirect = legacyLocalePath (location, pathname => resolvePageRoute (pathname) != null)
-  if (!(isLocaleCode (locale)) && !verticalPreview && redirect == null)
+  if (!(isLocaleCode (locale)) && redirect == null)
     return <NotFound/>
   if (isError && data == null)
     return <ServiceUnavailable/>
   if (data == null)
     return null
-  if (isLocaleCode (locale) || verticalPreview)
+  if (isLocaleCode (locale))
   {
-    return data.locales.some (entry => entry.code === contentLocale)
+    return data.locales.some (entry => entry.code === locale)
         ? <RoutedApp locales={data.locales}/>
         : <NotFound/>
   }
@@ -459,8 +455,7 @@ const LocaleRoute: FC = () => {
 const LocaleRedirect = ({ to }: { to: string }) => {
   const locale = useLocale ()
   const location = useLocation ()
-  return <Navigate to={localiseTo (
-      { ...location, pathname: to }, locale, location.pathname)} replace/>
+  return <Navigate to={switchLocalePath ({ ...location, pathname: to }, locale)} replace/>
 }
 
 

frontend/src/components/PostList.tsx

@@ -34,7 +34,7 @@ const PostList: FC<Props> = ({ posts, onClick }) => {
   const cardRef = useRef<HTMLDivElement> (null)
 
   return (
-      <div className="post-list flex flex-wrap gap-6 p-4">
+      <div className="flex flex-wrap gap-6 p-4">
 	{posts.map ((post, i) => {
 	  const sharedId = `page-${ post.id }`
 	  const layoutId = sharedId

frontend/src/components/PrefetchLink.tsx

@@ -1,10 +1,9 @@
 import { useQueryClient } from '@tanstack/react-query'
 import { forwardRef, useMemo } from 'react'
 import { flushSync } from 'react-dom'
-import { createPath, useLocation } from 'react-router-dom'
+import { createPath } from 'react-router-dom'
 
-import { isVerticalPreviewPath, localeFromPath,
-	 localiseTo, unlocalisedPath } from '@/lib/locales'
+import { localiseTo } from '@/lib/locales'
 import { useLocale, useLocaleNavigate } from '@/lib/useLocale'
 import { useOverlayStore } from '@/components/RouteBlockerOverlay'
 import { prefetchForURL } from '@/lib/prefetchers'
@@ -39,18 +38,15 @@ export default forwardRef<HTMLAnchorElement, Props> (({
 
   const navigate = useLocaleNavigate ()
   const locale = useLocale ()
-  const { pathname } = useLocation ()
   const qc = useQueryClient ()
   const behaviourSettings = useClientBehaviourSettings ()
   const linkPreloadMode = behaviourSettings.linkPreload ?? 'intent'
   const path = useMemo (
       () => {
-	const localised = localiseTo (to, locale, pathname)
-	const destination = typeof localised === 'string' ? localised : createPath (localised)
-	return (isVerticalPreviewPath (pathname) && localeFromPath (destination) === locale)
-	    ? `/mn-Mong${ unlocalisedPath (destination) }` : destination
+	const localised = localiseTo (to, locale)
+	return typeof localised === 'string' ? localised : createPath (localised)
       },
-      [to, locale, pathname],
+      [to, locale],
   )
   const url = useMemo (() => {
     return (new URL (path, currentRenderContext ()?.origin ?? 'http://localhost')).toString ()

frontend/src/components/TagSearch.test.tsx

@@ -1,120 +0,0 @@
-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, useRef, useState } from 'react'
+import { useEffect, 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, FormEvent, KeyboardEvent } from 'react'
+import type { ChangeEvent, FC, KeyboardEvent } from 'react'
 
 import type { Tag } from '@/types'
 
@@ -20,7 +20,6 @@ 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 ('')
@@ -75,34 +74,7 @@ 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':
@@ -118,12 +90,13 @@ const TagSearch: FC = () => {
       break
 
     case 'Enter':
+      if (activeIndex < 0)
+	break
+      ev.preventDefault ()
       {
-	const selected = suggestionsVsbl ? suggestions[activeIndex] : null
-	if (selected == null)
-	  break
-	ev.preventDefault ()
-	handleTagSelect (selected)
+	const selected = suggestions[activeIndex]
+	if (selected)
+	  handleTagSelect (selected)
       }
       break
 
@@ -132,6 +105,20 @@ 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) => {
@@ -157,9 +144,8 @@ const TagSearch: FC = () => {
   }, [location.search])
 
   return (
-      <form onSubmit={handleSubmit} className="relative w-full">
+      <div className="relative w-full">
 	<input type="text"
-	       enterKeyHint="search"
 	       data-shortcut-focus-search="true"
 	       placeholder={message ('labels.tagSearch').text}
 	       value={search}
@@ -167,18 +153,12 @@ 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}/>
-      </form>)
+      </div>)
 }
 
 export default TagSearch

frontend/src/components/TopNav.tsx

@@ -4,7 +4,7 @@ import { Globe } from 'lucide-react'
 import { Fragment, useEffect, useLayoutEffect, useRef, useState } from 'react'
 import { useLocation } from 'react-router-dom'
 
-import { useLocale, useLocaleNavigate, useVerticalPreview } from '@/lib/useLocale'
+import { useLocale, useLocaleNavigate } from '@/lib/useLocale'
 import LocalisedText, { formatUIString } from '@/components/LocalisedText'
 import Separator from '@/components/MenuSeparator'
 import PrefetchLink from '@/components/PrefetchLink'
@@ -137,7 +137,6 @@ export const menuOutline = (
 const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
   const { message, label } = useUITranslation ('shared')
   const locale = useLocale ()
-  const verticalPreview = useVerticalPreview ()
   const localeName = locales.find (entry => entry.code === locale)?.name
   const navigate = useLocaleNavigate ()
   const location = useLocation ()
@@ -181,12 +180,11 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
     let node: HTMLElement | null = el
     while (node != null && node !== nav)
     {
-      left += verticalPreview ? node.offsetTop : node.offsetLeft
+      left += node.offsetLeft
       const parent: Element | null = node.offsetParent
       node = parent instanceof HTMLElement ? parent : null
     }
-    const width = node === nav
-	? (verticalPreview ? el.offsetHeight : el.offsetWidth) : 0
+    const width = node === nav ? el.offsetWidth : 0
     const visible = width > 0
     setHL (current =>
 	(current.left === left && current.width === width && current.visible === visible)
@@ -204,7 +202,6 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
   const [moreVsbl, setMoreVsbl] = useState (false)
   const [openItemIdx, setOpenItemIdx] = useState (-1)
   const [submenuHeight, setSubmenuHeight] = useState (0)
-  const [submenuWidth, setSubmenuWidth] = useState (0)
   const [wikiId, setWikiId] = useState<number | null> (WikiIdBus.get ())
 
   const wikiIdStr = String (wikiId ?? '')
@@ -258,22 +255,8 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
       animationsOff
       ? undefined
       : (reducedAnimations
-	 ? 'transition-[transform,width,height] duration-75 ease-linear'
-	 : 'transition-[transform,width,height] duration-200 ease-out')
-  const submenuItemMotion = animationsOff ? { } : {
-      initial: { x: verticalPreview ? -40 : 0,
-	  y: verticalPreview ? 0 : -40, opacity: 0 },
-      animate: { x: 0, y: 0, opacity: 1 },
-      exit: { x: verticalPreview ? -40 : 0,
-	  y: verticalPreview ? 0 : -40, opacity: 0 } }
-  const submenuVariants = {
-      enter: (direction: -1 | 1) => ({
-	  x: verticalPreview ? direction * 24 : 0,
-	  y: verticalPreview ? 0 : direction * 24, opacity: 0 }),
-      centre: { x: 0, y: 0, opacity: 1 },
-      exit: (direction: -1 | 1) => ({
-	  x: verticalPreview ? (-direction) * 24 : 0,
-	  y: verticalPreview ? 0 : (-direction) * 24, opacity: 0 }) }
+	 ? 'transition-[transform,width] duration-75 ease-linear'
+	 : 'transition-[transform,width] duration-200 ease-out')
 
   const prevActiveIdxRef = useRef<number> (activeIdx)
 
@@ -304,14 +287,6 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 	return
       }
 
-      if (verticalPreview)
-      {
-	setDesktop (true)
-	setDensity ('auto')
-	measure (moreVsbl ? -1 : activeIdx)
-	return
-      }
-
       // Measure the same desktop elements while the mobile layout is active.
       layout.setAttribute ('data-measuring', '')
       const previousDensity = layout.getAttribute ('data-density') ?? 'auto'
@@ -376,8 +351,7 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
       removeEventListener ('resize', schedule)
       document.fonts?.removeEventListener ('loadingdone', schedule)
     }
-  }, [activeIdx, moreVsbl, desktop, density, user?.name, locale, locales,
-      menuLabels, verticalPreview])
+  }, [activeIdx, moreVsbl, desktop, density, user?.name, locale, locales, menuLabels])
 
   useEffect (() => {
     if (desktop == null || layoutReady)
@@ -404,8 +378,7 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
     measure (moreVsbl ? -1 : activeIdx)
     if (!(desktop))
       setMoreVsbl (false)
-  }, [activeIdx, moreVsbl, desktop, density, locale, animationMode,
-      menuLabels, verticalPreview])
+  }, [activeIdx, moreVsbl, desktop, density, locale, animationMode, menuLabels])
 
   useEffect (() => {
     const unsubscribe = WikiIdBus.subscribe (setWikiId)
@@ -419,7 +392,6 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 
     const update = () => {
       setSubmenuHeight (Math.ceil (content.getBoundingClientRect ().height))
-      setSubmenuWidth (Math.ceil (content.getBoundingClientRect ().width))
     }
     const observer =
 	typeof ResizeObserver === 'undefined' ? null : new ResizeObserver (update)
@@ -431,7 +403,7 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
       observer?.disconnect ()
       removeEventListener ('resize', update)
     }
-  }, [activeIdx, moreVsbl, desktop, density, locale, verticalPreview])
+  }, [activeIdx, moreVsbl, desktop, density, locale])
 
   useEffect (() => {
     setMenuOpen (false)
@@ -507,11 +479,8 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 		   className={cn ('absolute inset-y-0 h-12',
 				  'top-nav-highlight',
 				  highlightTransitionClass)}
-		   style={{ width:      verticalPreview ? '100%' : hl.width,
-			    height:     verticalPreview ? hl.width : undefined,
-			    transform:  verticalPreview
-				? `translateY(${ hl.left }px)`
-				: `translateX(${ hl.left }px)`,
+		   style={{ width:      hl.width,
+			    transform:  `translateX(${ hl.left }px)`,
 			    opacity:    hl.visible ? 1 : 0 }}/>
 
 	      {visibleMenu.map ((item, i) => (
@@ -560,18 +529,10 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 	  <div className="top-nav-account ml-auto flex min-w-0 items-center gap-2">
 	    <TopNavUser user={user}/>
 	    {localeSelector}
-	    {verticalPreview && (
-		<span className="vertical-preview-sample" lang="mn-Mong">
-		  ᠮᠣᠩᠭᠣᠯ
-		</span>)}
 	  </div>
 
 	  <div className="top-nav-mobile-controls ml-auto flex shrink-0 items-center gap-2">
 	    {menuOpen && localeSelector}
-	    {verticalPreview && (
-		<span className="vertical-preview-sample" lang="mn-Mong">
-		  ᠮᠣᠩᠭᠣᠯ
-		</span>)}
 	    <button
 		type="button"
 		className="top-nav-mobile-toggle shrink-0 whitespace-nowrap
@@ -593,9 +554,7 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 	      layout
 	      className="top-nav-desktop-submenu relative z-20 shrink-0
 			 overflow-hidden top-nav-submenu"
-	      animate={verticalPreview && desktop
-		  ? { width: submenuWidth, height: '100%' }
-		  : { width: 'auto', height: desktop == null ? 'auto' : submenuHeight }}
+	      animate={{ height: desktop == null ? 'auto' : submenuHeight }}
 	      onMouseLeave={() => {
 		if (moreVsbl)
 		  setMoreVsbl (false)
@@ -607,8 +566,7 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 	      onLayoutAnimationComplete={() => {
 		measure (highlightTargetRef.current)
 	      }}>
-	  <div ref={submenuContentRef}
-	      className={cn ('top-nav-submenu-content', moreVsbl && 'top-nav-more-menu')}>
+	  <div ref={submenuContentRef} className={cn (moreVsbl && 'top-nav-more-menu')}>
 	  {moreVsbl
 	   ? (
 	      moreMenu.map ((item, i) => (
@@ -618,11 +576,9 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 			  {...((item.visible ?? true)
 			       ? { layoutId: `menu-${ menu.indexOf (item) }` }
 			       : (animationsOff ? { }
-				  : { initial: {
-					  x: 40, y: verticalPreview ? 0 : -40, opacity: 0 },
+				  : { initial: { x: 40, y: -40, opacity: 0 },
 				      animate: { x: 0, y: 0, opacity: 1 },
-				      exit: {
-					  x: 40, y: verticalPreview ? 0 : -40, opacity: 0 } }))}
+				      exit: { x: 40, y: -40, opacity: 0 } }))}
 			  onLayoutAnimationComplete={() => measure (highlightTargetRef.current)}
 			  className="z-10 min-w-0 px-3 py-2 font-bold">
 			<h2>
@@ -643,7 +599,10 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 				  transition={topNavTransition}
 				  {...(visibleMenu[activeIdx] === item
 				       ? { layoutId: `submenu-${ menu.indexOf (item) }-${ j }` }
-				       : submenuItemMotion)}>
+				       : (animationsOff ? { }
+					  : { initial: { y: -40, opacity: 0 },
+					      animate: { y: 0, opacity: 1 },
+					      exit: { y: -40, opacity: 0 } }))}>
 				{subItem.component}
 			      </motion.div>)
 			  : (
@@ -653,7 +612,10 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 				  transition={topNavTransition}
 				  {...(visibleMenu[activeIdx] === item
 				       ? { layoutId: `submenu-${ menu.indexOf (item) }-${ j }` }
-				       : submenuItemMotion)}>
+				       : (animationsOff ? { }
+					  : { initial: { y: -40, opacity: 0 },
+					      animate: { y: 0, opacity: 1 },
+					      exit: { y: -40, opacity: 0 } }))}>
 				<PrefetchLink
 				    to={subItem.to}
 				    target={subItem.to.slice (0, 2) === '//' ? '_blank' : undefined}
@@ -671,8 +633,7 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 		  <div className="relative min-h-[40px]">
 		    {animationsOff
 		     ? (
-			 <div className="top-nav-submenu-items flex min-h-[40px]
-					 flex-wrap items-center px-3">
+			 <div className="flex min-h-[40px] flex-wrap items-center px-3">
 			   {(visibleMenu[activeIdx]?.subMenu ?? [])
 			    .filter (item => item.visible ?? true)
 			    .map ((item, i) => (
@@ -701,9 +662,10 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 			   <motion.div
 			       key={activeIdx}
 			       custom={dir}
-			       variants={submenuVariants}
-			       className="top-nav-submenu-items relative flex min-h-[40px]
-					  flex-wrap items-center px-3"
+			       variants={{ enter: (d: -1 | 1) => ({ y: d * 24, opacity: 0 }),
+					   centre: { y: 0, opacity: 1 },
+					   exit: (d: -1 | 1) => ({ y: (-d) * 24, opacity: 0 }) }}
+			       className="relative flex min-h-[40px] flex-wrap items-center px-3"
 			       initial="enter"
 			       animate="centre"
 			       exit="exit"

frontend/src/components/layout/MainArea.tsx

@@ -1,10 +1,7 @@
 import { motion } from 'framer-motion'
-import { useEffect, useRef } from 'react'
-import { useLocation } from 'react-router-dom'
 
 import { clientAnimationTransition } from '@/lib/clientAnimation'
 import { useClientBehaviourSettings } from '@/lib/useClientBehaviourSettings'
-import { useVerticalPreview } from '@/lib/useLocale'
 import { cn } from '@/lib/utils'
 
 import type { FC, ReactNode } from 'react'
@@ -12,71 +9,21 @@ import type { FC, ReactNode } from 'react'
 type Props = {
     children:   ReactNode
     className?: string
-    animateLayout?: boolean
-    verticalContent?: boolean }
+    animateLayout?: boolean }
 
 
-const MainArea: FC<Props> = (
-    { children, className, animateLayout = true, verticalContent = false },
-) => {
+const MainArea: FC<Props> = ({ children, className, animateLayout = true }) => {
   const behaviourSettings = useClientBehaviourSettings ()
-  const verticalPreview = useVerticalPreview ()
-  const horizontal = verticalPreview && verticalContent
-  const { pathname, search } = useLocation ()
-  const rootRef = useRef<HTMLElement | null> (null)
   const animationMode = behaviourSettings.animation ?? 'normal'
   const layoutTransition = clientAnimationTransition (
       animationMode,
-      { normal: { duration: .2, ease: 'easeOut' as const } })
-
-  useEffect (() => {
-    if (horizontal && rootRef.current != null)
-      rootRef.current.scrollLeft = 0
-  }, [horizontal, pathname, search])
-
-  useEffect (() => {
-    const root = rootRef.current
-    if (!horizontal || root == null)
-      return
-
-    const handleWheel = (event: WheelEvent) => {
-      if (event.ctrlKey || event.metaKey || event.shiftKey
-	  || event.deltaX !== 0 || event.deltaY === 0 || event.defaultPrevented)
-	return
-
-      // Nested tables, forms and code blocks retain their own scrolling.
-      let node = event.target instanceof HTMLElement ? event.target : null
-      while (node != null && node !== root)
-      {
-	if (node.matches ('input, select, textarea, [contenteditable="true"]'))
-	  return
-	const style = getComputedStyle (node)
-	if ((/auto|scroll/.test (style.overflowY) && node.scrollHeight > node.clientHeight)
-	    || (/auto|scroll/.test (style.overflowX) && node.scrollWidth > node.clientWidth))
-	  return
-	node = node.parentElement
-      }
-
-      const unit = event.deltaMode === 1 ? 16 : (event.deltaMode === 2 ? root.clientWidth : 1)
-      const delta = event.deltaY * unit
-      if ((delta < 0 && root.scrollLeft <= 0)
-	  || (delta > 0 && root.scrollLeft + root.clientWidth >= root.scrollWidth))
-	return
-      event.preventDefault ()
-      root.scrollLeft += delta
-    }
-
-    root.addEventListener ('wheel', handleWheel, { passive: false })
-    return () => root.removeEventListener ('wheel', handleWheel)
-  }, [horizontal])
+      { normal: { duration: .2, ease: 'easeOut' as const } },
+  )
 
   return (
       <motion.main
-	  ref={rootRef}
-	  data-vertical-content={horizontal || undefined}
-	  tabIndex={horizontal ? 0 : undefined}
 	  transition={{ layout: layoutTransition }}
-	  className={cn ('main-area flex-1 overflow-y-auto p-4', className)}
+	  className={cn ('flex-1 overflow-y-auto p-4', className)}
 	  layout={(animationMode === 'off' || !animateLayout) ? false : 'position'}>
 	{children}
       </motion.main>)

frontend/src/components/layout/SidebarComponent.tsx

@@ -1,14 +1,13 @@
 import { motion } from 'framer-motion'
-import { useCallback, useEffect, useRef, useState } from 'react'
 import { Helmet } from 'react-helmet-async'
 
 import { clientAnimationTransition } from '@/lib/clientAnimation'
 import { useClientBehaviourSettings } from '@/lib/useClientBehaviourSettings'
 import { cn } from '@/lib/utils'
 import { useUITranslation } from '@/lib/useUITranslation'
-import { useVerticalPreview } from '@/lib/useLocale'
 
 import type { CSSProperties, FC, MouseEvent, PointerEvent, ReactNode } from 'react'
+import { useCallback, useEffect, useRef, useState } from 'react'
 
 type SidebarSide = 'left' | 'right'
 
@@ -24,12 +23,12 @@ type Props = {
 
 type ResizeState = {
     pointerId:  number
-    startSize: number
+    startWidth: number
     startX:     number
-    startY:     number
-    verticalPreview: boolean
     side:       SidebarSide }
 
+type PendingPressState = ResizeState & { startY: number }
+
 const DEFAULT_SIDEBAR_WIDTH = 256
 const MIN_SIDEBAR_WIDTH = 192
 const MIN_MAIN_WIDTH = 360
@@ -38,97 +37,84 @@ const LONG_PRESS_DELAY_MS = 350
 const TOUCH_MOVE_THRESHOLD_PX = 8
 
 
-const storageKeyForSidebar = (
-    sidebarKey: string,
-    side: SidebarSide,
-    verticalPreview = false,
-): string =>
-    `sidebar:${ sidebarKey }:${ side }:${ verticalPreview ? 'height' : 'width' }`
+const storageKeyForSidebar = (sidebarKey: string, side: SidebarSide): string =>
+    `sidebar:${ sidebarKey }:${ side }:width`
 
 
-const getSidebarMaxWidth = (containerSize: number): number => {
+const getSidebarMaxWidth = (containerWidth: number): number => {
   const viewportWidth =
-      typeof window === 'undefined' ? containerSize : window.innerWidth
+      typeof window === 'undefined' ? containerWidth : window.innerWidth
   const viewportMaxWidth = Math.floor (viewportWidth * MAX_VIEWPORT_WIDTH_RATIO)
-  const containerMaxWidth = Math.floor (containerSize - MIN_MAIN_WIDTH)
+  const containerMaxWidth = Math.floor (containerWidth - MIN_MAIN_WIDTH)
   const dynamicMaxWidth = Math.min (viewportMaxWidth, containerMaxWidth)
 
   return Math.max (MIN_SIDEBAR_WIDTH, dynamicMaxWidth)
 }
 
 
-const readStoredSidebarSize = (
+const readStoredSidebarWidth = (
     sidebarKey: string,
-    side: SidebarSide,
-    verticalPreview: boolean,
-): number => {
+    side: SidebarSide): number => {
   if (typeof window === 'undefined')
     return DEFAULT_SIDEBAR_WIDTH
 
-  try
-  {
-    const value = window.localStorage.getItem (
-	storageKeyForSidebar (sidebarKey, side, verticalPreview))
-    const size = value == null ? Number.NaN : Number (value)
-    return Number.isFinite (size) ? size : DEFAULT_SIDEBAR_WIDTH
-  }
-  catch
-  {
-    return DEFAULT_SIDEBAR_WIDTH
-  }
+  const value = window.localStorage.getItem (storageKeyForSidebar (sidebarKey, side))
+  const width = value == null ? Number.NaN : Number (value)
+
+  return Number.isFinite (width) ? width : DEFAULT_SIDEBAR_WIDTH
 }
 
 
-const SidebarComponent: FC<Props> = (
-    { children, className, maxWidth, maxWidthRatio, animateLayout = true,
-      onWidthChange, sidebarKey, side = 'left' },
-) => {
+const SidebarComponent: FC<Props> = ({
+    children,
+    className,
+    maxWidth,
+    maxWidthRatio,
+    animateLayout = true,
+    onWidthChange,
+    sidebarKey,
+    side = 'left',
+}) => {
   const { message } = useUITranslation ('shared')
   const behaviourSettings = useClientBehaviourSettings ()
-  const verticalPreview = useVerticalPreview ()
   const animationMode = behaviourSettings.animation ?? 'normal'
   const layoutTransition = clientAnimationTransition (
       animationMode,
-      { normal: { duration: .2, ease: 'easeOut' as const } })
+      { normal: { duration: .2, ease: 'easeOut' as const } },
+  )
   const rootRef = useRef<HTMLDivElement | null> (null)
   const maxWidthRef = useRef (maxWidth)
   const maxWidthRatioRef = useRef (maxWidthRatio)
-  const getContainerSize = useCallback (() => {
-    const container = rootRef.current?.closest ('[data-sidebar-container]')
-    return verticalPreview
-	? container?.clientHeight ?? window.innerHeight
-	: container?.clientWidth ?? window.innerWidth
-  }, [verticalPreview])
-  const getClampedSize = useCallback ((
-      nextSize: number,
-      containerSize: number,
-  ): number => {
-    if (verticalPreview)
-    {
-      const maximum = Math.max (64, Math.min (
-	  window.innerHeight * .6, containerSize - 160))
-      return Math.min (maximum, Math.max (64, nextSize))
-    }
+  const getContainerWidth = useCallback (() => {
+    const containerWidth = rootRef.current
+	?.closest ('[data-sidebar-container]')
+	?.clientWidth
+    ?? window.innerWidth
+    return containerWidth
+  }, [])
+  const getClampedWidth = useCallback ((
+      nextWidth: number,
+      containerWidth: number): number => {
     const viewportWidth =
-	typeof window === 'undefined' ? containerSize : window.innerWidth
+	typeof window === 'undefined' ? containerWidth : window.innerWidth
     const viewportMaxWidth = Math.floor (viewportWidth * MAX_VIEWPORT_WIDTH_RATIO)
     const ratioMaxWidth = maxWidthRatioRef.current == null
-	? Infinity : Math.floor (containerSize * maxWidthRatioRef.current)
+	? Infinity : Math.floor (containerWidth * maxWidthRatioRef.current)
     const configuredMaxWidth = maxWidthRef.current == null
-	? getSidebarMaxWidth (containerSize)
+	? getSidebarMaxWidth (containerWidth)
 	: Math.max (MIN_SIDEBAR_WIDTH,
 	    Math.min (viewportMaxWidth, maxWidthRef.current))
     const maxAllowedWidth = Math.max (MIN_SIDEBAR_WIDTH,
 	Math.min (ratioMaxWidth, configuredMaxWidth))
 
-    return Math.min (maxAllowedWidth, Math.max (MIN_SIDEBAR_WIDTH, nextSize))
-  }, [verticalPreview])
+    return Math.min (maxAllowedWidth, Math.max (MIN_SIDEBAR_WIDTH, nextWidth))
+  }, [])
 
-  const [size, setSize] = useState (DEFAULT_SIDEBAR_WIDTH)
+  const [width, setWidth] = useState (DEFAULT_SIDEBAR_WIDTH)
   const [resizing, setResizing] = useState (false)
-  const sizeRef = useRef (size)
+  const widthRef = useRef (width)
   const longPressTimerRef = useRef<ReturnType<typeof setTimeout> | null> (null)
-  const pendingPressRef = useRef<ResizeState | null> (null)
+  const pendingPressRef = useRef<PendingPressState | null> (null)
   const resizeRef = useRef<ResizeState | null> (null)
   const bodyStyleRef = useRef<{ cursor: string, userSelect: string } | null> (null)
 
@@ -162,7 +148,7 @@ const SidebarComponent: FC<Props> = (
 	  userSelect: document.body.style.userSelect }
     }
 
-    document.body.style.cursor = state.verticalPreview ? 'row-resize' : 'col-resize'
+    document.body.style.cursor = 'col-resize'
     document.body.style.userSelect = 'none'
   }, [clearLongPressTimer])
 
@@ -173,50 +159,43 @@ const SidebarComponent: FC<Props> = (
     const state = resizeRef.current
     resizeRef.current = null
 
-    try
-    {
-      if (state != null)
-	window.localStorage.setItem (
-	    storageKeyForSidebar (sidebarKey, state.side, state.verticalPreview),
-	    String (sizeRef.current))
-    }
-    catch
-    {
-      // Resizing remains usable when browser storage is unavailable.
-    }
+    if (state != null)
+      window.localStorage.setItem (
+	  storageKeyForSidebar (sidebarKey, state.side),
+	  String (widthRef.current))
 
     setResizing (false)
     restoreBodyStyle ()
   }, [clearLongPressTimer, restoreBodyStyle, sidebarKey])
 
-  const applySize = useCallback ((nextSize: number) => {
-    if (nextSize === sizeRef.current)
+  const applyWidth = useCallback ((nextWidth: number) => {
+    if (nextWidth === widthRef.current)
       return
 
-    sizeRef.current = nextSize
-    setSize (nextSize)
+    widthRef.current = nextWidth
+    setWidth (nextWidth)
   }, [])
 
   useEffect (() => {
     maxWidthRef.current = maxWidth
     maxWidthRatioRef.current = maxWidthRatio
-    const containerSize = getContainerSize ()
-    const nextSize = getClampedSize (sizeRef.current, containerSize)
-    applySize (nextSize)
-  }, [applySize, getClampedSize, getContainerSize, maxWidth, maxWidthRatio])
+    const containerWidth = getContainerWidth ()
+    const nextWidth = getClampedWidth (widthRef.current, containerWidth)
+    applyWidth (nextWidth)
+  }, [applyWidth, getClampedWidth, getContainerWidth, maxWidth, maxWidthRatio])
 
-  const updateSize = useCallback ((clientX: number, clientY: number) => {
+  const updateWidth = useCallback ((clientX: number) => {
     const state = resizeRef.current
     if (state == null)
       return
 
-    const containerSize = getContainerSize ()
-    const delta = state.verticalPreview
-	? clientY - state.startY
-	: (state.side === 'left' ? clientX - state.startX : state.startX - clientX)
-    const nextSize = getClampedSize (state.startSize + delta, containerSize)
-    applySize (nextSize)
-  }, [applySize, getClampedSize, getContainerSize])
+    const containerWidth = getContainerWidth ()
+    const delta = state.side === 'left'
+		  ? clientX - state.startX
+		  : state.startX - clientX
+    const nextWidth = getClampedWidth (state.startWidth + delta, containerWidth)
+    applyWidth (nextWidth)
+  }, [applyWidth, getClampedWidth, getContainerWidth])
 
   const handlePointerDown = (ev: PointerEvent<HTMLDivElement>) => {
     if (ev.pointerType !== 'mouse' && ev.pointerType !== 'touch')
@@ -232,10 +211,8 @@ const SidebarComponent: FC<Props> = (
     const state = {
 	pointerId: ev.pointerId,
 	side,
-	startSize: sizeRef.current,
-	startX: ev.clientX,
-	startY: ev.clientY,
-	verticalPreview }
+	startWidth: widthRef.current,
+	startX: ev.clientX }
 
     if (ev.pointerType === 'mouse')
     {
@@ -243,7 +220,7 @@ const SidebarComponent: FC<Props> = (
       return
     }
 
-    pendingPressRef.current = state
+    pendingPressRef.current = { ...state, startY: ev.clientY }
     clearLongPressTimer ()
     longPressTimerRef.current = setTimeout (() => {
       if (pendingPressRef.current != null)
@@ -257,7 +234,7 @@ const SidebarComponent: FC<Props> = (
     if (resizeRef.current != null)
     {
       ev.preventDefault ()
-      updateSize (ev.clientX, ev.clientY)
+      updateWidth (ev.clientX)
       return
     }
 
@@ -285,58 +262,58 @@ const SidebarComponent: FC<Props> = (
     finishResize ()
   }
 
-  const resetSize = useCallback (() => {
-    const containerSize = getContainerSize ()
-    const nextSize = getClampedSize (DEFAULT_SIDEBAR_WIDTH, containerSize)
-    applySize (nextSize)
-    window.localStorage.removeItem (
-	storageKeyForSidebar (sidebarKey, side, verticalPreview))
-  }, [applySize, getClampedSize, getContainerSize, sidebarKey, side, verticalPreview])
+  const resetWidth = useCallback (() => {
+    const containerWidth = getContainerWidth ()
+    const nextWidth = getClampedWidth (DEFAULT_SIDEBAR_WIDTH, containerWidth)
+    applyWidth (nextWidth)
+    window.localStorage.removeItem (storageKeyForSidebar (sidebarKey, side))
+  }, [applyWidth, getClampedWidth, getContainerWidth, sidebarKey, side])
 
   const handleDoubleClick = (ev: MouseEvent<HTMLDivElement>) => {
     ev.preventDefault ()
     ev.stopPropagation ()
-    resetSize ()
+    resetWidth ()
   }
 
   useEffect (() => {
-    const containerSize = getContainerSize ()
-    const nextSize = getClampedSize (
-	readStoredSidebarSize (sidebarKey, side, verticalPreview),
-	containerSize)
-    applySize (nextSize)
-  }, [applySize, getClampedSize, getContainerSize, sidebarKey, side, verticalPreview])
+    const containerWidth = getContainerWidth ()
+    const nextWidth = getClampedWidth (
+	readStoredSidebarWidth (sidebarKey, side),
+	containerWidth)
+    applyWidth (nextWidth)
+  }, [applyWidth, getClampedWidth, getContainerWidth, sidebarKey, side])
 
   useEffect (() => {
-    const containerSize = getContainerSize ()
-    const nextSize = getClampedSize (sizeRef.current, containerSize)
-    applySize (nextSize)
-  }, [applySize, getClampedSize, getContainerSize])
+    const containerWidth = getContainerWidth ()
+    const nextWidth = getClampedWidth (widthRef.current, containerWidth)
+    applyWidth (nextWidth)
+  }, [applyWidth, getClampedWidth, getContainerWidth])
 
   useEffect (() => {
     if (typeof window === 'undefined')
       return
 
     const handleResize = () => {
-      const containerSize = getContainerSize ()
-      const nextSize = getClampedSize (sizeRef.current, containerSize)
-      applySize (nextSize)
+      const containerWidth = getContainerWidth ()
+      const nextWidth = getClampedWidth (widthRef.current, containerWidth)
+      applyWidth (nextWidth)
     }
 
     window.addEventListener ('resize', handleResize)
     return () => window.removeEventListener ('resize', handleResize)
-  }, [applySize, getClampedSize, getContainerSize])
+  }, [applyWidth, getClampedWidth, getContainerWidth])
 
   useEffect (() => {
-    if (!verticalPreview)
-      onWidthChange?.(size)
-  }, [onWidthChange, size, verticalPreview])
+    onWidthChange?.(width)
+  }, [onWidthChange, width])
 
-  useEffect (() => () => finishResize (), [finishResize, verticalPreview])
+  useEffect (() => () => {
+    clearLongPressTimer ()
+    restoreBodyStyle ()
+  }, [clearLongPressTimer, restoreBodyStyle])
 
   const style = {
-      '--sidebar-width': `${ size }px`,
-      '--sidebar-height': `${ size }px` } as CSSProperties
+      '--sidebar-width': `${ width }px` } as CSSProperties
 
   return (
       <motion.div
@@ -345,7 +322,7 @@ const SidebarComponent: FC<Props> = (
 	  transition={{ layout: layoutTransition }}
 	  style={style}
 	  className={cn (
-	      'sidebar-panel relative w-full md:w-[var(--sidebar-width)] md:shrink-0 md:h-full',
+	      'relative w-full md:w-[var(--sidebar-width)] md:shrink-0 md:h-full',
 	      className)}>
 	<Helmet>
 	  <style>
@@ -368,16 +345,16 @@ const SidebarComponent: FC<Props> = (
 
 	<div
 	    role="separator"
-	    aria-orientation={verticalPreview ? 'horizontal' : 'vertical'}
-	    aria-label={message (verticalPreview ? 'labels.menu' : 'sidebarWidth').text}
-	    lang={message (verticalPreview ? 'labels.menu' : 'sidebarWidth').language}
+	    aria-orientation="vertical"
+	    aria-label={message ('sidebarWidth').text}
+	    lang={message ('sidebarWidth').language}
 	    onPointerDown={handlePointerDown}
 	    onPointerMove={handlePointerMove}
 	    onPointerUp={handlePointerEnd}
 	    onPointerCancel={handlePointerEnd}
 	    onDoubleClick={handleDoubleClick}
 	    className={cn (
-		'sidebar-resize hidden md:block absolute top-0 bottom-0 z-20 w-4 cursor-col-resize',
+		'hidden md:block absolute top-0 bottom-0 z-20 w-4 cursor-col-resize',
 		'touch-none select-none',
 		side === 'left' ? '-right-2' : '-left-2',
 		'before:absolute before:top-0 before:bottom-0 before:w-px',

frontend/src/entry-server.tsx

@@ -9,8 +9,7 @@ import { createStaticHandler, createStaticRouter,
 import { AppFrame, appRoutes, resolvePageRoute } from '@/App'
 import { apiGet, isApiError } from '@/lib/api'
 import { createUII18n } from '@/lib/i18n'
-import { fetchLocales, isLocaleCode, isVerticalPreviewPath,
-	 legacyLocalePath } from '@/lib/locales'
+import { fetchLocales, isLocaleCode, legacyLocalePath } from '@/lib/locales'
 import { localesKeys, sessionKeys } from '@/lib/queryKeys'
 import { withRenderContext } from '@/lib/renderContext.server'
 
@@ -73,15 +72,13 @@ export const render = async (
       pathname => resolvePageRoute (pathname) != null)
   const pathname = legacy == null ? url.pathname : new URL (legacy, origin).pathname
   const segment = pathname.split ('/')[1]
-  const verticalPreview = isVerticalPreviewPath (pathname)
   const known = resolvePageRoute (pathname)
   if (legacy != null && known != null)
     return { status: 308, location: legacy }
   const locale = isLocaleCode (segment) ? segment : 'ja'
-  const routePrefix = verticalPreview ? 'mn-Mong' : locale
   if (known?.route.handle?.redirectTo != null)
     return { status: 308,
-      location: `/${routePrefix}${known.route.handle.redirectTo}${url.search}` }
+      location: `/${locale}${known.route.handle.redirectTo}${url.search}` }
   const requestContext: RenderContext & { status: number } = {
       pathname: url.pathname, origin, apiBaseURL,
       ...authentication, status: 200 }
@@ -109,8 +106,7 @@ export const render = async (
 	}
       }
       const prepare = known?.route.handle?.prepare
-      const routeLocaleValid = isLocaleCode (segment) || verticalPreview
-      let status = known == null || !active || !routeLocaleValid ? 404 : 200
+      let status = known == null || !active || !isLocaleCode (segment) ? 404 : 200
       if (status === 200 && known?.route.handle?.authentication != null
 	  && client.getQueryData (sessionKeys.current) == null)
 	status = 401

frontend/src/index.css

@@ -625,503 +625,3 @@ body
   white-space: nowrap;
   will-change: transform;
 }
-
-/* Loaded only by the development-only sample, with the OFL alongside the font. */
-@font-face
-{
-  font-family: 'BTRC Mongolian Preview';
-  src: url('/fonts/noto-sans-mongolian/NotoSansMongolian-Regular.ttf') format('truetype');
-  font-weight: 400;
-  font-style: normal;
-  font-display: swap;
-}
-
-/* Development-only /mn-Mong layout. Unannotated pages retain horizontal text. */
-[data-vertical-preview]
-{
-  min-width: 0;
-  min-height: 0;
-  overflow: hidden;
-}
-
-[data-vertical-preview] > :not(.top-nav-layout)
-{
-  flex: 1;
-  min-width: 0;
-  min-height: 0;
-  overflow: auto;
-}
-
-[data-vertical-preview] [data-sidebar-container]
-{
-  display: flex;
-  flex-direction: column;
-  min-width: 0;
-  min-height: 0;
-  overflow: hidden;
-}
-
-[data-vertical-preview] .main-area
-{
-  min-width: 0;
-  min-height: 0;
-  overscroll-behavior: contain;
-}
-
-[data-vertical-preview] .main-area[data-vertical-content]
-{
-  overflow-x: auto;
-  overflow-y: hidden;
-  overscroll-behavior-x: contain;
-}
-
-[data-vertical-preview] .sidebar-panel
-{
-  width: 100%;
-  height: var(--sidebar-height);
-  min-height: 0;
-  flex: none;
-}
-
-[data-vertical-preview] .sidebar
-{
-  display: flex;
-  align-items: flex-start;
-  gap: 1rem;
-  direction: ltr;
-  overflow-x: auto;
-  overflow-y: hidden;
-  overscroll-behavior: contain;
-}
-
-[data-vertical-preview] .sidebar > *
-{
-  flex-shrink: 0;
-}
-
-[data-vertical-preview] .sidebar > form
-{
-  width: 16rem;
-  height: 100%;
-  overflow-y: auto;
-}
-
-[data-vertical-preview] .sidebar > form > ul
-{
-  position: relative;
-}
-
-[data-vertical-preview] .sidebar > div
-{
-  writing-mode: vertical-lr;
-  text-orientation: mixed;
-  height: 100%;
-  margin: 0;
-}
-
-[data-vertical-preview] .sidebar :is(h2, h3, ul)
-{
-  margin: 0;
-  margin-block-end: 1rem;
-}
-
-[data-vertical-preview] .sidebar-resize
-{
-  display: block;
-  inset: auto 0 -.5rem;
-  width: 100%;
-  height: 1rem;
-  cursor: row-resize;
-}
-
-[data-vertical-preview] .sidebar-resize::before
-{
-  inset: 50% 0 auto;
-  width: 100%;
-  height: 1px;
-}
-
-[data-vertical-preview] .vertical-preview-sample
-{
-  writing-mode: vertical-lr;
-  text-orientation: mixed;
-  font-family: 'BTRC Mongolian Preview', 'Mongolian Baiti', sans-serif;
-  font-size: 1.25rem;
-  line-height: 1.5;
-  flex-shrink: 0;
-}
-
-/* The post grid fills each column downwards before continuing to the right. */
-[data-vertical-preview] .posts-main-area > div
-{
-  display: flex;
-  height: 100%;
-  width: max-content;
-  margin: 0;
-  gap: 1rem;
-}
-
-[data-vertical-preview] .posts-main-area > div > div:first-child
-{
-  flex-direction: column;
-  justify-content: flex-start;
-  writing-mode: vertical-lr;
-  text-orientation: mixed;
-}
-
-[data-vertical-preview] .posts-main-area > div > div:last-child
-{
-  display: flex;
-  width: max-content;
-  height: 100%;
-  margin: 0;
-  gap: 1rem;
-}
-
-[data-vertical-preview] .main-area[data-vertical-content] .post-list
-{
-  display: grid;
-  grid-auto-flow: column;
-  grid-auto-columns: 10rem;
-  grid-template-rows: repeat(auto-fill, min(10rem, 100%));
-  flex: none;
-  width: max-content;
-  height: 100%;
-  writing-mode: horizontal-tb;
-}
-
-[data-vertical-preview] .main-area[data-vertical-content] .post-list > a
-{
-  height: 100%;
-}
-
-[data-vertical-preview] .main-area[data-vertical-content] nav
-{
-  flex: none;
-  align-self: flex-start;
-  margin: 0;
-  writing-mode: horizontal-tb;
-}
-
-[data-vertical-preview] .tags-main-area
-{
-  display: flex;
-  align-items: stretch;
-  gap: 1.5rem;
-}
-
-[data-vertical-preview] .tag-list-filter
-{
-  flex: none;
-  width: min(24rem, 75vw);
-  max-width: none;
-  overflow-y: auto;
-}
-
-[data-vertical-preview] .tag-list-filter h1
-{
-  writing-mode: vertical-lr;
-  text-orientation: mixed;
-  max-height: 8rem;
-  margin-block: 0;
-}
-
-[data-vertical-preview] .tag-list-filter input[type='number']
-{
-  max-width: 7rem;
-}
-
-[data-vertical-preview] .tag-list-results
-{
-  display: flex;
-  flex: none;
-  gap: 1rem;
-  max-width: none;
-  margin: 0;
-}
-
-[data-vertical-preview] .tag-list-table
-{
-  max-width: none;
-  overflow-x: visible;
-  overflow-y: auto;
-}
-
-[data-vertical-preview] .tag-list-table table
-{
-  writing-mode: vertical-lr;
-  text-orientation: mixed;
-  inline-size: max-content;
-  block-size: max-content;
-  min-width: 0;
-}
-
-[data-vertical-preview] .tag-list-table col
-{
-  width: auto;
-}
-
-[data-vertical-preview] .tag-list-table :is(th, td)
-{
-  min-inline-size: 2rem;
-  max-inline-size: 16rem;
-  text-align: start;
-}
-
-[data-vertical-preview] .tag-list-table thead
-{
-  border-bottom: 0;
-  border-block-end: 2px solid currentColor;
-}
-
-[data-vertical-preview] .tag-list-table td:nth-child(2),
-[data-vertical-preview] .tag-list-table time
-{
-  writing-mode: horizontal-tb;
-  white-space: nowrap;
-}
-
-[data-vertical-preview] :is(.sidebar, .tag-list-table, .wiki-main-area) .tag-marquee,
-[data-vertical-preview] :is(.sidebar, .tag-list-table, .wiki-main-area) .tag-marquee__static
-{
-  white-space: normal;
-  overflow: visible;
-  text-overflow: clip;
-  max-inline-size: 16rem;
-  opacity: 1;
-}
-
-[data-vertical-preview] :is(.sidebar, .tag-list-table, .wiki-main-area) .tag-marquee__animated
-{
-  display: none;
-}
-
-/* Prose flows through the viewport height and grows into columns on the right. */
-[data-vertical-preview] .wiki-main-area
-{
-  display: flex;
-  gap: 1rem;
-}
-
-[data-vertical-preview] .wiki-main-area > div
-{
-  flex: none;
-  writing-mode: vertical-lr;
-  text-orientation: mixed;
-  margin: 0;
-}
-
-[data-vertical-preview] .wiki-main-area > div > span
-{
-  writing-mode: horizontal-tb;
-}
-
-[data-vertical-preview] .wiki-main-area article,
-[data-vertical-preview] .posts-main-area .localised-document
-{
-  writing-mode: vertical-lr;
-  text-orientation: mixed;
-  inline-size: 100%;
-  block-size: max-content;
-  max-width: none;
-  margin: 0;
-  flex: none;
-}
-
-[data-vertical-preview] .main-area[data-vertical-content] .localised-document
-{
-  max-width: none;
-  overflow: visible;
-}
-
-[data-vertical-preview] .wiki-main-area article :is(h1, h2, h3, h4, p, ul, ol, blockquote)
-{
-  margin: 0;
-  margin-block: 1em;
-}
-
-[data-vertical-preview] .wiki-main-area article :is(ul, ol)
-{
-  padding: 0;
-  padding-inline-start: 1.5em;
-}
-
-[data-vertical-preview] .wiki-main-area article :is(img, video, iframe, svg)
-{
-  writing-mode: horizontal-tb;
-  max-height: 100%;
-  max-width: none;
-  object-fit: contain;
-}
-
-[data-vertical-preview] .wiki-main-area article :is(pre, table, .not-prose),
-[data-vertical-preview] .main-area[data-vertical-content] :is(code, time, input, select, textarea)
-{
-  writing-mode: horizontal-tb;
-  text-orientation: mixed;
-}
-
-[data-vertical-preview] .wiki-main-area article :is(pre, table, .not-prose)
-{
-  display: inline-block;
-  max-height: 100%;
-  max-width: min(48rem, 80vw);
-  overflow: auto;
-  vertical-align: top;
-}
-
-[data-vertical-preview] .wiki-main-area article .not-prose
-{
-  width: max-content;
-  height: 100%;
-}
-
-[data-vertical-preview] .wiki-main-area .not-prose > div
-{
-  display: flex;
-  flex-direction: column;
-  height: 100%;
-  margin: 0;
-}
-
-[data-vertical-preview] .wiki-main-area .not-prose > div > div:last-child
-{
-  flex: 1;
-  min-height: 0;
-}
-
-@media (min-width: 768px)
-{
-  [data-vertical-preview].app-layout
-  {
-    flex-direction: row;
-  }
-
-  [data-vertical-preview] .top-nav-layout
-  {
-    display: flex;
-    width: max-content;
-    max-width: 50vw;
-    height: 100%;
-  }
-
-  [data-vertical-preview] .top-nav-bar
-  {
-    flex-direction: column;
-    flex: none;
-    width: 7rem;
-    height: 100%;
-    padding: .5rem;
-    gap: .5rem;
-  }
-
-  [data-vertical-preview] .top-nav-primary
-  {
-    flex-direction: column;
-    flex: 1;
-    min-height: 0;
-    width: 100%;
-    height: auto;
-    overflow-y: auto;
-  }
-
-  [data-vertical-preview] .top-nav-brand-link
-  {
-    writing-mode: vertical-lr;
-    text-orientation: mixed;
-    max-height: 9rem;
-    white-space: normal;
-    margin-block: .5rem;
-  }
-
-  [data-vertical-preview] .top-nav-desktop-menu
-  {
-    flex-direction: column;
-    width: 100%;
-    height: auto;
-  }
-
-  [data-vertical-preview] .top-nav-desktop-menu > div:not(.top-nav-highlight)
-  {
-    width: 100%;
-  }
-
-  [data-vertical-preview] .top-nav-desktop-menu .top-nav-menu-link
-  {
-    justify-content: center;
-    width: 100%;
-    min-height: 3rem;
-    height: auto;
-    padding: .5rem;
-  }
-
-  [data-vertical-preview] .top-nav-menu-link > :not(svg, select),
-  [data-vertical-preview] .top-nav-more-menu h2
-  {
-    writing-mode: vertical-lr;
-    text-orientation: mixed;
-    max-height: 9rem;
-    white-space: normal;
-  }
-
-  [data-vertical-preview] .top-nav-highlight
-  {
-    inset-inline-start: 0;
-  }
-
-  [data-vertical-preview] .top-nav-account
-  {
-    flex-direction: column;
-    width: 100%;
-    margin: 0;
-  }
-
-  [data-vertical-preview] .top-nav-account .top-nav-user-desktop
-  {
-    max-width: 100%;
-    margin: 0;
-    padding: 0;
-  }
-
-  [data-vertical-preview] .top-nav-locale-name
-  {
-    display: inline;
-    writing-mode: horizontal-tb;
-  }
-
-  [data-vertical-preview] .top-nav-desktop-submenu
-  {
-    min-width: 0;
-    height: 100%;
-  }
-
-  [data-vertical-preview] .top-nav-submenu-content
-  {
-    width: max-content;
-    max-width: 35vw;
-    height: 100%;
-    overflow-y: auto;
-    overflow-x: hidden;
-  }
-
-  [data-vertical-preview] :is(.top-nav-submenu-items, .top-nav-more-links)
-  {
-    flex-direction: column;
-    flex-wrap: nowrap;
-    align-items: stretch;
-  }
-
-  [data-vertical-preview] .top-nav-submenu-items .top-nav-menu-link
-  {
-    justify-content: center;
-  }
-}
-
-@media (max-width: 767px)
-{
-  [data-vertical-preview] .top-nav-layout
-  {
-    max-height: 50dvh;
-    overflow-y: auto;
-  }
-}

frontend/src/lib/locales.ts

@@ -28,11 +28,6 @@ export const localeFromPath = (pathname: string): LocaleCode | null => {
 }
 
 
-// A development-only layout route; API and dictionary locales stay unchanged.
-export const isVerticalPreviewPath = (pathname: string): boolean =>
-    import.meta.env.DEV && /^\/mn-Mong(?:[/?#]|$)/.test (pathname)
-
-
 export const resolveViewingLocale = (
     pathname: string,
     routeLocale?: unknown,
@@ -45,22 +40,20 @@ export const currentViewingLocale = (): LocaleCode =>
 
 
 export const unlocalisedPath = (pathname: string): string => {
-  const locale = isVerticalPreviewPath (pathname) ? 'mn-Mong' : localeFromPath (pathname)
+  const locale = localeFromPath (pathname)
   return locale == null ? pathname : pathname.slice (locale.length + 1) || '/'
 }
 
 
-export const localiseTo = (to: To, locale: LocaleCode, viewingPath = ''): To => {
+export const localiseTo = (to: To, locale: LocaleCode): To => {
   const pathname = typeof to === 'string' ? to : to.pathname
   if (pathname == null
       || !(pathname.startsWith ('/'))
       || pathname.startsWith ('//')
-      || localeFromPath (pathname) != null
-      || isVerticalPreviewPath (pathname))
+      || localeFromPath (pathname) != null)
     return to
 
-  const prefix = isVerticalPreviewPath (viewingPath) ? 'mn-Mong' : locale
-  const localised = `/${ prefix }${ pathname }`
+  const localised = `/${ locale }${ pathname }`
   return typeof to === 'string' ? localised : { ...to, pathname: localised }
 }
 
@@ -80,8 +73,7 @@ export const legacyLocalePath = (
     location: { pathname: string; search: string; hash: string },
     isPage: (pathname: string) => boolean = () => false,
 ): string | null => {
-  if (localeFromPath (location.pathname) != null
-      || isVerticalPreviewPath (location.pathname) || !isPage (location.pathname))
+  if (localeFromPath (location.pathname) != null || !isPage (location.pathname))
     return null
   return switchLocalePath (location, automaticallySelectedLocale ())
 }

frontend/src/lib/useLocale.ts

@@ -1,7 +1,7 @@
 import { useCallback } from 'react'
 import { useLocation, useNavigate, useParams } from 'react-router-dom'
 
-import { isVerticalPreviewPath, localiseTo, resolveViewingLocale } from '@/lib/locales'
+import { localiseTo, resolveViewingLocale } from '@/lib/locales'
 
 import type { NavigateFunction, NavigateOptions, To } from 'react-router-dom'
 
@@ -18,15 +18,10 @@ export const useLocale = (): LocaleCode => {
 export const useLocaleNavigate = (): NavigateFunction => {
   const navigate = useNavigate ()
   const locale = useLocale ()
-  const { pathname } = useLocation ()
   return useCallback ((to: To | number, options?: NavigateOptions) => {
     if (typeof to === 'number')
       navigate (to)
     else
-      navigate (localiseTo (to, locale, pathname), options)
-  }, [locale, navigate, pathname])
+      navigate (localiseTo (to, locale), options)
+  }, [locale, navigate])
 }
-
-
-export const useVerticalPreview = (): boolean =>
-    isVerticalPreviewPath (useLocation ().pathname)

frontend/src/pages/posts/PostListPage.tsx

@@ -146,7 +146,7 @@ const PostListPage: FC = () => {
 				    JSON.stringify (statesToSave))
 	}}/>
 
-	<MainArea className="posts-main-area" verticalContent>
+	<MainArea>
 	  <TabGroup
 	      rightAddon={
 		  <label className="flex items-center gap-2 text-xs text-muted-foreground">

frontend/src/pages/tags/TagListPage.tsx

@@ -220,10 +220,10 @@ const TagListPage: FC = () => {
   }), [page, totalPages, location.search]))
 
   return (
-      <MainArea className="tags-main-area min-w-0" verticalContent>
+      <MainArea className="min-w-0">
 	<PageHead title={message ('title')}/>
 
-	<div className="tag-list-filter max-w-xl">
+	<div className="max-w-xl">
 	  <div className="flex flex-wrap items-center justify-between gap-3">
 	    <PageTitle>{label ('title')}</PageTitle>
 	    <label className="flex items-center gap-2 text-xs text-muted-foreground">
@@ -358,8 +358,8 @@ const TagListPage: FC = () => {
 
 	{isError && <p role="alert">{label ('common:fetchError')}</p>}
 	{loading ? label ('common:loading') : (results.length > 0 ? (
-	    <div className="tag-list-results mt-4 min-w-0 max-w-full">
-	      <div className="tag-list-table min-w-0 max-w-full overflow-x-auto">
+	    <div className="mt-4 min-w-0 max-w-full">
+	      <div className="min-w-0 max-w-full overflow-x-auto">
 		<table className="w-full min-w-[2000px] table-auto border-collapse">
 		  <colgroup>
 		    <col className="w-72"/>

frontend/src/pages/wiki/WikiDetailPage.tsx

@@ -114,7 +114,7 @@ const WikiDetailPage: FC = () => {
     return <NotFound/>
 
   return (
-      <MainArea className="wiki-main-area" verticalContent>
+      <MainArea>
 	<PageHead title={{
 	    text: `${displayTitle}${deprecated
 		? message ('labels.deprecatedSuffix').text : ''} Wiki`,