Simplify chat UI broadcasts with broadcasts_to

- switch generated message model broadcasting from explicit create/update/destroy callbacks to broadcasts_to
- keep only broadcast_append_chunk for streamed chunk appends
- make message role partials accept message local fallback (user/assistant/system/tool/tool_calls ||= local_assigns[:message]) so broadcasts_to rendering works with role-based partial conventions
- keep create.turbo_stream focused on form reset and remove update.turbo_stream template generation
- update chat UI generator specs and Rails docs to match the new broadcast + partial-local behavior

Author: crmne

docs/_advanced/rails.md

@@ -180,6 +180,8 @@ The generated chat UI follows one convention: each message partial uses the loca
 
 This comes from Rails partial rendering: `render @chat.messages` calls `to_partial_path`, and Rails injects a local named after that partial.
 
+For compatibility with model broadcasts (`broadcasts_to`), generated message partials also accept a `message` local as a fallback.
+
 #### Tool Call and Tool Result Partials
 
 Tool-specific partials are generated under `app/views/messages/tool_calls` and `app/views/messages/tool_results`:
@@ -205,8 +207,7 @@ Using fixed locals keeps the templates dumb and predictable.
 
 Turbo Stream templates used by the generated chat UI:
 
-- `messages/create.turbo_stream.erb` resets the message form for `MessagesController#create` and appends a rendered message when invoked from model create broadcasts.
-- `messages/update.turbo_stream.erb` is used by model update broadcasts to re-render the message row.
+- `messages/create.turbo_stream.erb` resets the message form for `MessagesController#create`.
 
 #### Generator Options
 

lib/generators/ruby_llm/chat_ui/chat_ui_generator.rb

@@ -77,8 +77,6 @@ def create_views
                  "app/views/#{message_view_path}/tool_results/_default.html.erb"
         template ui_template('views/messages/create.turbo_stream.erb'),
                  "app/views/#{message_view_path}/create.turbo_stream.erb"
-        template ui_template('views/messages/update.turbo_stream.erb'),
-                 "app/views/#{message_view_path}/update.turbo_stream.erb"
         template ui_template('views/messages/_content.html.erb'), "app/views/#{message_view_path}/_content.html.erb"
         template ui_template('views/messages/_form.html.erb'), "app/views/#{message_view_path}/_form.html.erb"
 
@@ -156,29 +154,9 @@ def add_broadcasting_to_message_model
         # e.g., for LLM::Message, the chat association might be :llm_chat
         chat_association = chat_table_name.singularize
 
-        partial_path = message_model_name.underscore.pluralize
-
         broadcasting_callbacks = <<-RUBY
 
-  after_create_commit :broadcast_message_created
-  after_update_commit :broadcast_message_updated
-  after_destroy_commit :broadcast_message_removed
-
-  def broadcast_message_created
-    broadcast_render_later_to "#{chat_var}_\#{#{chat_association}_id}",
-      template: "#{partial_path}/create",
-      locals: { #{msg_var}: self }
-  end
-
-  def broadcast_message_updated
-    broadcast_render_later_to "#{chat_var}_\#{#{chat_association}_id}",
-      template: "#{partial_path}/update",
-      locals: { #{msg_var}: self }
-  end
-
-  def broadcast_message_removed
-    broadcast_remove_to "#{chat_var}_\#{#{chat_association}_id}"
-  end
+  broadcasts_to ->(#{msg_var}) { "#{chat_var}_\#{#{msg_var}.#{chat_association}_id}" }, inserts_by: :append
 
   def broadcast_append_chunk(content)
     broadcast_append_to "#{chat_var}_\#{#{chat_association}_id}",

lib/generators/ruby_llm/chat_ui/templates/tailwind/views/messages/_assistant.html.erb.tt

@@ -1,3 +1,4 @@
+<%% assistant ||= local_assigns[:message] %>
 <div id="<%= message_variable_name %>_<%%= assistant.id %>" class="w-full sm:w-auto my-5 space-y-3 rounded-md px-3 py-2 bg-green-50">
   <div>
     <span class="inline-block rounded px-2 py-0.5 text-xs font-medium bg-green-100 text-green-700">

lib/generators/ruby_llm/chat_ui/templates/tailwind/views/messages/_system.html.erb.tt

@@ -1,3 +1,4 @@
+<%% system ||= local_assigns[:message] %>
 <div id="<%= message_variable_name %>_<%%= system.id %>" class="w-full sm:w-auto my-5 space-y-3 rounded-md px-3 py-2 bg-gray-50 border border-gray-200">
   <div>
     <span class="inline-block rounded px-2 py-0.5 text-xs font-medium bg-gray-200 text-gray-700">

lib/generators/ruby_llm/chat_ui/templates/tailwind/views/messages/_tool.html.erb.tt

@@ -1 +1,2 @@
+<%% tool ||= local_assigns[:message] %>
 <%%= render tool_result_partial(tool), tool: tool %>

lib/generators/ruby_llm/chat_ui/templates/tailwind/views/messages/_tool_calls.html.erb.tt

@@ -1,3 +1,4 @@
+<%% tool_calls ||= local_assigns[:message] %>
 <%% tool_calls.<%= tool_call_variable_name.pluralize %>.each do |tool_call| %>
   <%%= render tool_call_partial(tool_call), tool_calls: tool_calls, tool_call: tool_call %>
 <%% end %>

lib/generators/ruby_llm/chat_ui/templates/tailwind/views/messages/_user.html.erb.tt

@@ -1,3 +1,4 @@
+<%% user ||= local_assigns[:message] %>
 <div id="<%= message_variable_name %>_<%%= user.id %>" class="w-full sm:w-auto my-5 space-y-3 rounded-md px-3 py-2 bg-blue-50">
   <div>
     <span class="inline-block rounded px-2 py-0.5 text-xs font-medium bg-blue-100 text-blue-700">

lib/generators/ruby_llm/chat_ui/templates/views/messages/_assistant.html.erb.tt

@@ -1,3 +1,4 @@
+<%% assistant ||= local_assigns[:message] %>
 <div id="<%= message_variable_name %>_<%%= assistant.id %>" class="<%= message_variable_name %>"
      style="margin-bottom: 20px; padding: 10px; border-left: 3px solid #28a745;">
   <div style="font-weight: bold; margin-bottom: 5px;">Assistant</div>

lib/generators/ruby_llm/chat_ui/templates/views/messages/_system.html.erb.tt

@@ -1,3 +1,4 @@
+<%% system ||= local_assigns[:message] %>
 <div id="<%= message_variable_name %>_<%%= system.id %>" class="<%= message_variable_name %>"
      style="margin-bottom: 20px; padding: 10px; border-left: 3px solid #6b7280; background: #f9fafb;">
   <div style="font-weight: bold; margin-bottom: 5px; color: #374151;">System</div>

lib/generators/ruby_llm/chat_ui/templates/views/messages/_tool.html.erb.tt

@@ -1 +1,2 @@
+<%% tool ||= local_assigns[:message] %>
 <%%= render tool_result_partial(tool), tool: tool %>