Replace the full container since we want to get back to the initial state

To see the boost button again

app/views/cards/comments/reactions/create.turbo_stream.erb

@@ -1 +1,3 @@
-<%= turbo_stream.append([ @comment, :reactions ], partial: "cards/comments/reactions/reaction", locals: { reaction: @reaction }) %>
+<%= turbo_stream.replace([ @comment, :reacting ]) do %>
+  <%= render "cards/comments/reactions/reactions", comment: @comment.reload %>
+<% end %>

app/views/cards/comments/reactions/new.html.erb

@@ -2,7 +2,7 @@
   <%= form_with model: [ @comment.card, @comment, Reaction.new ],
         class: "reaction reaction__form expanded",
         html: { aria: { label: "New reaction" } },
-        data: { controller: "form reaction-emoji", turbo_frame: dom_id(@comment, :reacting), action: "keydown.esc->form#cancel submit->form#preventEmptySubmit turbo:submit-end->form#reset" } do |form| %>
+        data: { controller: "form reaction-emoji", turbo_frame: dom_id(@comment, :reacting), action: "keydown.esc->form#cancel submit->form#preventEmptySubmit" } do |form| %>
     <label class="reaction__form-label flex gap" style="--column-gap: 0.4ch;">
       <figure class="reaction__avatar margin-none flex-item-no-shrink">
         <%= avatar_tag Current.user %>

test/controllers/cards/comments/reactions_controller_test.rb

@@ -10,7 +10,7 @@ class Cards::Comments::ReactionsControllerTest < ActionDispatch::IntegrationTest
   test "create" do
     assert_difference -> { @comment.reactions.count }, 1 do
       post card_comment_reactions_path(@comment.card, @comment, format: :turbo_stream), params: { reaction: { content: "Great work!" } }
-      assert_turbo_stream action: :append, target: dom_id(@comment, :reactions)
+      assert_turbo_stream action: :replace, target: dom_id(@comment, :reacting)
     end
   end