fix: added delete buttons on chats and have chat titeling (maybe)

lib/bds/ai/chat.ex

@@ -23,6 +23,8 @@ 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 20
+  @chat_title_max_length 30
   @chat_max_tool_rounds 10
   @default_context_window 128_000
 
@@ -59,6 +61,22 @@ defmodule BDS.AI.Chat do
     Repo.get(ChatConversation, conversation_id)
   end
 
+  @spec delete_chat_conversation(String.t()) :: {:ok, :deleted} | {:error, :not_found | term()}
+  def delete_chat_conversation(conversation_id) when is_binary(conversation_id) do
+    case Repo.get(ChatConversation, conversation_id) do
+      nil ->
+        {:error, :not_found}
+
+      %ChatConversation{} = conversation ->
+        Repo.delete_all(from message in ChatMessage, where: message.conversation_id == ^conversation_id)
+
+        case Repo.delete(conversation) do
+          {:ok, _conversation} -> {:ok, :deleted}
+          {:error, reason} -> {:error, reason}
+        end
+    end
+  end
+
   @spec available_chat_models(String.t() | nil) :: [map()]
   def available_chat_models(current_model \\ nil) do
     endpoint_models = configured_chat_models()
@@ -303,7 +321,7 @@ defmodule BDS.AI.Chat do
 
   defp fallback_provider_name(_provider), do: "Other"
 
-  defp do_send_chat_message(conversation, _user_message, opts) do
+  defp do_send_chat_message(conversation, user_message, opts) do
     runtime = Keyword.get(opts, :runtime, OpenAICompatibleRuntime)
     project_id = Keyword.get(opts, :project_id, active_project_id())
 
@@ -327,11 +345,106 @@ defmodule BDS.AI.Chat do
              runtime,
              opts,
              @chat_max_tool_rounds
-           ) do
+           ),
+         {:ok, reply} <- maybe_generate_chat_title(conversation.id, user_message.content, reply, opts) do
       {:ok, reply}
     end
   end
 
+  defp maybe_generate_chat_title(conversation_id, user_content, reply, opts) do
+    conversation = Repo.get!(ChatConversation, conversation_id)
+
+    cond do
+      chat_user_message_count(conversation_id) != 1 ->
+        {:ok, reply}
+
+      not generated_chat_title?(conversation.title, conversation.model) ->
+        {:ok, reply}
+
+      true ->
+        case generate_chat_title(user_content, opts) do
+          {:ok, title} when is_binary(title) and title != "" ->
+            now = Persistence.now_ms()
+
+            conversation
+            |> ChatConversation.changeset(%{title: title, updated_at: now})
+            |> Repo.update()
+            |> case do
+              {:ok, updated_conversation} ->
+                {:ok, %{reply | conversation: format_conversation(updated_conversation)}}
+
+              {:error, _reason} ->
+                {:ok, reply}
+            end
+
+          _other ->
+            {:ok, reply}
+        end
+    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
+      {:ok, sanitize_chat_title(Map.get(response, :content))}
+    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. 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,