diff --git a/backend/app/representations/post_repr.rb b/backend/app/representations/post_repr.rb
index 2ea60fe..1590ce0 100644
--- a/backend/app/representations/post_repr.rb
+++ b/backend/app/representations/post_repr.rb
@@ -18,7 +18,12 @@ module PostRepr
   module_function
 
   def base post, current_user = nil, host: nil
-    json = common(post, host:)
+    json =
+        if host.present?
+          common(post, host:)
+        else
+          common(post)
+        end
     json['tags'] = tag_json(post)
     json['uploaded_user'] = post.uploaded_user && UserRepr.base(post.uploaded_user)
     json['viewed'] = current_user ? current_user.viewed?(post) : false
@@ -27,30 +32,58 @@ module PostRepr
 
   def detail post, current_user = nil, parent_posts: [], child_posts: [],
              sibling_posts: { }, related: [], host: nil
-    base(post, current_user, host:).merge(
-        'parent_posts' => cards(parent_posts, host:),
-        'child_posts' => cards(child_posts, host:),
-        'sibling_posts' => sibling_posts.transform_keys(&:to_s).transform_values { |posts|
-          cards(posts, host:)
-        },
-        'related' => cards(related, host:))
+    if host.present?
+      base(post, current_user, host:).merge(
+          'parent_posts' => cards(parent_posts, host:),
+          'child_posts' => cards(child_posts, host:),
+          'sibling_posts' => sibling_posts.transform_keys(&:to_s).transform_values { |posts|
+            cards(posts, host:)
+          },
+          'related' => cards(related, host:))
+    else
+      base(post, current_user).merge(
+          'parent_posts' => cards(parent_posts),
+          'child_posts' => cards(child_posts),
+          'sibling_posts' => sibling_posts.transform_keys(&:to_s).transform_values { |posts|
+            cards(posts)
+          },
+          'related' => cards(related))
+    end
   end
 
   def card post, host: nil
-    common(post, host:).merge('parent_posts' => [], 'child_posts' => [])
+    if host.present?
+      common(post, host:).merge('parent_posts' => [], 'child_posts' => [])
+    else
+      common(post).merge('parent_posts' => [], 'child_posts' => [])
+    end
   end
 
   def cards posts, host: nil
-    posts.map { |post| card(post, host:) }
+    if host.present?
+      posts.map { |post| card(post, host:) }
+    else
+      posts.map { |post| card(post) }
+    end
   end
 
   def many posts, current_user = nil, host: nil
-    posts.map { |p| base(p, current_user, host:) }
+    if host.present?
+      posts.map { |p| base(p, current_user, host:) }
+    else
+      posts.map { |p| base(p, current_user) }
+    end
   end
 
   def common post, host: nil
     BASE_FIELDS.to_h { |field| [field.to_s, post.public_send(field)] }
-               .merge('thumbnail' => thumbnail_url(post, host:))
+               .merge(
+                   'thumbnail' =>
+                       if host.present?
+                         thumbnail_url(post, host:)
+                       else
+                         thumbnail_url(post)
+                       end)
   end
 
   def tag_json post
@@ -68,10 +101,10 @@ module PostRepr
   def thumbnail_url post, host: nil
     return nil unless post.thumbnail.attached?
 
-    Rails.application.routes.url_helpers.rails_storage_proxy_url(
-        post.thumbnail,
-        only_path: false,
-        host:)
+    options = { only_path: false }
+    options[:host] = host if host.present?
+
+    Rails.application.routes.url_helpers.rails_storage_proxy_url(post.thumbnail, **options)
   rescue ActionController::UrlGenerationError, ArgumentError, URI::InvalidURIError => e
     Rails.logger.warn(
         "PostRepr.thumbnail_url failed post_id=#{post.id} " \