Show a file in a message's rich text by its name, whatever its variants

Showing an image's preview when its variant had already been made tied the cached message to state
that changes without touching it: a variant made after the message was cached would never show. It also
cost a query per embedded image, since Action Text loads the embeds without their variant records.
Nothing in the app makes those variants, so the partial no longer looks at them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bj8KnxpTf9sj2Ysa8aLAVa

app/views/active_storage/blobs/_blob.html.erb

@@ -1,14 +1,7 @@
 <%# Files are posted as a message's own attachment, which gets its preview when it's posted; the composer adds none to
-    the rich text. One that's there anyway shows a preview only if it was already made, rather than linking to a URL
-    that makes it, on any view, for as long as it fails. %>
-<% preview = blob.variant(resize_to_limit: local_assigns[:in_gallery] ? [ 800, 600 ] : [ 1024, 768 ]) if blob.variable? %>
-<% preview = nil unless preview&.processed? %>
-
-<figure class="attachment attachment--<%= preview ? "preview" : "file" %> attachment--<%= blob.filename.extension %>">
-  <% if preview %>
-    <%= image_tag preview, alt: blob.try(:alt) %>
-  <% end %>
-
+    the rich text. One that's there anyway is shown by its name, with no preview: Action Text's partial links to a URL
+    that makes one on view, and nothing else in the app would make it. %>
+<figure class="attachment attachment--file attachment--<%= blob.filename.extension %>">
   <figcaption class="attachment__caption">
     <% if caption = blob.try(:caption) %>
       <%= caption %>

test/helpers/messages_helper_test.rb

@@ -1,6 +1,8 @@
 require "test_helper"
 
 class MessagesHelperTest < ActionView::TestCase
+  include ActiveRecord::Assertions::QueryAssertions
+
   test "message_presentation neutralizes unsafe URI schemes in links" do
     message = Message.create! room: rooms(:pets), body: '<div><a href="javascript:alert(1)">x</a></div>', client_message_id: "0015", creator: users(:jason)
 
@@ -26,19 +28,23 @@ class MessagesHelperTest < ActionView::TestCase
   end
 
   test "message_presentation shows an image in the rich text as a file, rather than making its preview on view" do
-    presentation = view.message_presentation(message_with_file_in_rich_text("moon.jpg", "image/jpeg"))
+    message = Message.with_attachment_details.find(message_with_file_in_rich_text("moon.jpg", "image/jpeg").id)
+
+    presentation = nil
+    assert_no_queries_match(/active_storage_variant_records/) { presentation = view.message_presentation(message) }
 
     assert_no_match %r{/representations/}, presentation
     assert_match %r{<span class="attachment__name">moon\.jpg</span>}, presentation
   end
 
-  test "message_presentation shows an image in the rich text whose preview was already made" do
+  test "message_presentation shows an image in the rich text as a file even when its preview was made" do
     message = message_with_file_in_rich_text("moon.jpg", "image/jpeg")
     message.body.embeds.first.blob.variant(resize_to_limit: [ 1024, 768 ]).processed
 
     presentation = view.message_presentation(message.reload)
 
-    assert_match %r{<img[^>]+src="[^"]*/representations/[^"]*moon\.jpg"}, presentation
+    assert_no_match %r{/representations/}, presentation
+    assert_match %r{<span class="attachment__name">moon\.jpg</span>}, presentation
   end
 
   test "message_presentation shows a video in the rich text as a file" do