fix: more refactorings for cleaning code

lib/bds/ai/chat.ex

@@ -9,6 +9,7 @@ defmodule BDS.AI.Chat do
   alias BDS.AI.CatalogProvider
   alias BDS.AI.ChatConversation
   alias BDS.AI.ChatMessage
+  alias BDS.AI.ChatTitleGenerator
   alias BDS.AI.ChatTools
   alias BDS.AI.InFlight
   alias BDS.AI.OpenAICompatibleRuntime
@@ -24,8 +25,6 @@ defmodule BDS.AI.Chat do
 
   @default_system_prompt "You are the bDS AI backend. Be precise, prefer structured JSON when asked, and avoid inventing blog facts."
   @default_max_output_tokens 16_384
-  @title_max_output_tokens 256
-  @chat_title_max_length 30
   @chat_max_tool_rounds 10
   @chat_await_timeout_margin_ms 5_000
   @default_context_window 128_000
@@ -34,7 +33,7 @@ defmodule BDS.AI.Chat do
   def start_chat(attrs \\ %{}) when is_map(attrs) do
     now = Persistence.now_ms()
     model = MapUtils.attr(attrs, :model)
-    title = MapUtils.attr(attrs, :title) || generated_chat_title(model)
+    title = MapUtils.attr(attrs, :title) || ChatTitleGenerator.generated_chat_title(model)
 
     %ChatConversation{}
     |> ChatConversation.changeset(%{
@@ -430,11 +429,11 @@ defmodule BDS.AI.Chat do
     conversation = Repo.get!(ChatConversation, conversation_id)
 
     cond do
-      chat_user_message_count(conversation_id) < 1 ->
+      ChatTitleGenerator.chat_user_message_count(conversation_id) < 1 ->
         Logger.debug("Chat title generation skipped reason=:no_user_messages")
         {:ok, reply}
 
-      not generated_chat_title?(conversation.title, conversation.model) ->
+      not ChatTitleGenerator.generated_chat_title?(conversation.title, conversation.model) ->
         Logger.debug(
           "Chat title generation skipped reason=:conversation_already_titled title=#{inspect(conversation.title)}"
         )
@@ -444,7 +443,7 @@ defmodule BDS.AI.Chat do
       true ->
         Logger.debug("Chat title generation requested conversation_id=#{conversation_id}")
 
-        case generate_chat_title(user_content, opts) do
+        case ChatTitleGenerator.generate_chat_title(user_content, opts) do
           {:ok, title} when is_binary(title) and title != "" ->
             now = Persistence.now_ms()
 
@@ -465,87 +464,6 @@ defmodule BDS.AI.Chat do
     end
   end
 
-  defp generate_chat_title(user_content, opts) when is_binary(user_content) do
-    runtime = Keyword.get(opts, :runtime, OpenAICompatibleRuntime)
-
-    with {:ok, endpoint, model, mode} <- Runtime.resolve_target(:chat_title, opts),
-         :ok <- Runtime.validate_target(:chat_title, model, mode),
-         request <- build_chat_title_request(user_content, model),
-         {:ok, response} <-
-           runtime.generate(Runtime.endpoint_with_model(endpoint, model), request, opts) do
-      title = sanitize_chat_title(Map.get(response, :content))
-
-      if title == "" do
-        Logger.warning("Chat title generation returned an empty title",
-          model: model,
-          content: inspect(Map.get(response, :content)),
-          usage: inspect(Map.get(response, :usage))
-        )
-      end
-
-      {:ok, title}
-    else
-      {:error, reason} = error ->
-        Logger.warning("Chat title generation failed", reason: inspect(reason))
-        error
-
-      other ->
-        Logger.warning("Chat title generation failed", reason: inspect(other))
-        other
-    end
-  end
-
-  defp build_chat_title_request(user_content, model) do
-    %{
-      operation: :chat_title,
-      model: model,
-      max_output_tokens: @title_max_output_tokens,
-      messages: [
-        %{
-          "role" => "system",
-          "content" =>
-            "Generate an ultra-short title (2-3 words, max 25 characters) for this conversation. Focus ONLY on the topic. Ignore any capability disclaimers. Do not include reasoning. Output ONLY the title text."
-        },
-        %{"role" => "user", "content" => "Topic: #{String.slice(user_content, 0, 100)}"}
-      ]
-    }
-  end
-
-  defp sanitize_chat_title(title) when is_binary(title) do
-    title =
-      title
-      |> String.trim()
-      |> String.trim_leading("\"")
-      |> String.trim_leading("'")
-      |> String.trim_trailing("\"")
-      |> String.trim_trailing("'")
-      |> String.trim_trailing(".")
-      |> String.trim_trailing("!")
-      |> String.trim_trailing("?")
-
-    if String.length(title) > @chat_title_max_length do
-      String.slice(title, 0, @chat_title_max_length - 3) <> "..."
-    else
-      title
-    end
-  end
-
-  defp sanitize_chat_title(_title), do: ""
-
-  defp chat_user_message_count(conversation_id) do
-    Repo.aggregate(
-      from(message in ChatMessage,
-        where: message.conversation_id == ^conversation_id and message.role == :user
-      ),
-      :count,
-      :id
-    )
-  end
-
-  defp generated_chat_title?(title, model) do
-    title in [generated_chat_title(nil), generated_chat_title(model)]
-  end
-
   defp chat_round(
          _conversation,
          _messages,
@@ -882,9 +800,6 @@ defmodule BDS.AI.Chat do
     )
   end
 
-  defp generated_chat_title(nil), do: "New Chat"
-  defp generated_chat_title(model), do: "Chat with #{model}"
-
   defp load_chat_messages(conversation_id) do
     Repo.all(
       from message in ChatMessage,