From df9e98132e088ca7d74e9c54a5164f3e2ce165f2 Mon Sep 17 00:00:00 2001
From: Codex Night Worker <codex-night@localhost>
Date: Thu, 12 Nov 2026 19:45:42 +0900
Subject: [PATCH] AI: address review on PR #462

---
 backend/app/controllers/posts_controller.rb | 35 +++++++++++++++++++--
 1 file changed, 32 insertions(+), 3 deletions(-)

diff --git a/backend/app/controllers/posts_controller.rb b/backend/app/controllers/posts_controller.rb
index 3929863..84a467f 100644
--- a/backend/app/controllers/posts_controller.rb
+++ b/backend/app/controllers/posts_controller.rb
@@ -37,6 +37,8 @@ class PostsController < ApplicationController
 
     offset = (page - 1) * limit
 
+    history_join_required = order[0] == 'updated_at' || updated_between.any?(&:present?)
+
     q =
         filtered_posts(locale)
         .preload(:external_tags, :uploaded_user, :parents, :children,
@@ -54,9 +56,25 @@ class PostsController < ApplicationController
     end
     q = q.where('posts.created_at >= ?', created_between[0]) if created_between[0]
     q = q.where('posts.created_at <= ?', created_between[1]) if created_between[1]
-    q = q.where('posts.updated_at >= ?', updated_between[0]) if updated_between[0]
-    q = q.where('posts.updated_at <= ?', updated_between[1]) if updated_between[1]
     count_scope = q
+    if history_join_required
+      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 history_join_required
+      q = q.select('posts.*', "#{ updated_at_all_sql } AS updated_at")
+    end
 
     sort_sql =
         case order[0]
@@ -64,6 +82,8 @@ class PostsController < ApplicationController
           'COALESCE(posts.original_created_before - INTERVAL 1 MINUTE,' +
           'posts.original_created_from,' +
           'posts.created_at) '
+        when 'updated_at'
+          updated_at_all_sql
         else
           "posts.#{ order[0] }"
         end
@@ -71,11 +91,20 @@ class PostsController < ApplicationController
              .limit(limit)
              .offset(offset)
              .to_a
+    latest_version_times =
+        if history_join_required
+          { }
+        else
+          HistoryAccess.visible(PostVersion.where(post_id: posts.map(&:id)))
+              .group(:post_id).maximum(:created_at)
+        end
 
     count_scope = count_scope.except(:select, :order)
 
     render json: { posts: posts.map { |post|
-      PostRepr.base(post, language_code: locale.language_code).tap do |json|
+      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|
         json['thumbnail'] =
             if post.thumbnail.attached?
               rails_storage_proxy_url(post.thumbnail, only_path: false)