fix: more fixes to AI chat

lib/bds/ai/chat.ex

@@ -479,10 +479,44 @@ defmodule BDS.AI.Chat do
 
     case Catalog.decode_nullable_json(message.tool_calls) do
       nil -> base
-      tool_calls -> Map.put(base, "tool_calls", tool_calls)
+      tool_calls -> Map.put(base, "tool_calls", tool_calls_for_runtime(tool_calls))
     end
   end
 
+  defp tool_calls_for_runtime(tool_calls) when is_list(tool_calls) do
+    Enum.map(tool_calls, &tool_call_for_runtime/1)
+  end
+
+  defp tool_calls_for_runtime(tool_calls), do: tool_calls
+
+  defp tool_call_for_runtime(%{"type" => "function", "function" => %{} = _function} = tool_call) do
+    tool_call
+  end
+
+  defp tool_call_for_runtime(%{"id" => id, "name" => name} = tool_call) do
+    %{
+      "id" => id,
+      "type" => "function",
+      "function" => %{
+        "name" => name,
+        "arguments" => Jason.encode!(tool_call["arguments"] || %{})
+      }
+    }
+  end
+
+  defp tool_call_for_runtime(%{id: id, name: name} = tool_call) do
+    %{
+      "id" => id,
+      "type" => "function",
+      "function" => %{
+        "name" => name,
+        "arguments" => Jason.encode!(Map.get(tool_call, :arguments) || %{})
+      }
+    }
+  end
+
+  defp tool_call_for_runtime(tool_call), do: tool_call
+
   defp truncate_chat_messages(messages, model, tools) do
     context_window = model_context_window(model)
     reserve = min(@default_max_output_tokens, max(div(context_window, 4), 512))

lib/bds/desktop/shell_live/chat_editor/message_build.ex

@@ -62,6 +62,16 @@ defmodule BDS.Desktop.ShellLive.ChatEditor.MessageBuild do
             next_turn_index = turn_index + 1
             {entries, start_entry(message, next_turn_index, assigns), next_turn_index}
 
+          :assistant ->
+            next_entry = start_entry(message, turn_index, assigns)
+
+            if tool_only_assistant_entry?(current_entry) do
+              {entries, merge_tool_only_entry(current_entry, next_entry), turn_index}
+            else
+              entries = finalize_entry(entries, current_entry)
+              {entries, next_entry, turn_index}
+            end
+
           _other ->
             entries = finalize_entry(entries, current_entry)
             {entries, start_entry(message, turn_index, assigns), turn_index}
@@ -99,6 +109,22 @@ defmodule BDS.Desktop.ShellLive.ChatEditor.MessageBuild do
     end
   end
 
+  defp tool_only_assistant_entry?(%{role: :assistant, content: content} = entry) do
+    String.trim(content || "") == "" and
+      (entry.tool_markers != [] or entry.inline_surfaces != [] or entry.tool_surfaces != [])
+  end
+
+  defp tool_only_assistant_entry?(_entry), do: false
+
+  defp merge_tool_only_entry(tool_entry, assistant_entry) do
+    %{
+      assistant_entry
+      | tool_markers: tool_entry.tool_markers ++ assistant_entry.tool_markers,
+        inline_surfaces: tool_entry.inline_surfaces ++ assistant_entry.inline_surfaces,
+        tool_surfaces: tool_entry.tool_surfaces ++ assistant_entry.tool_surfaces
+    }
+  end
+
   defp pending_user_message(_messages, nil), do: nil
 
   defp pending_user_message(messages, %{message: message}) when is_binary(message) do

test/bds/ai_test.exs

@@ -602,6 +602,17 @@ defmodule BDS.AITest do
     assert get_in(render_chart_schema, ["series", "items", "properties", "segments"]) != nil
 
     assert Enum.any?(second_request.messages, fn message -> message["role"] == "tool" end)
+
+    assert Enum.any?(second_request.messages, fn message ->
+             message["role"] == "assistant" and
+               message["tool_calls"] == [
+                 %{
+                   "id" => "call-blog-stats",
+                   "type" => "function",
+                   "function" => %{"name" => "blog_stats", "arguments" => "{}"}
+                 }
+               ]
+           end)
   end
 
   test "chat does not prompt models to emit textual tool calls when tools are unavailable" do

test/bds/desktop/shell_live_test.exs

@@ -2216,6 +2216,73 @@ defmodule BDS.Desktop.ShellLiveTest do
     assert html =~ "Posts"
   end
 
+  test "chat editor folds tool-only assistant steps into the final assistant answer" do
+    assert {:ok, conversation} = AI.start_chat(%{title: "Tool Chat", model: "gpt-4.1"})
+
+    now = Persistence.now_ms()
+
+    Repo.insert!(
+      BDS.AI.ChatMessage.changeset(%BDS.AI.ChatMessage{}, %{
+        conversation_id: conversation.id,
+        role: :user,
+        content: "Show posts per month",
+        created_at: now
+      })
+    )
+
+    Repo.insert!(
+      BDS.AI.ChatMessage.changeset(%BDS.AI.ChatMessage{}, %{
+        conversation_id: conversation.id,
+        role: :assistant,
+        content: nil,
+        tool_calls:
+          Jason.encode!([
+            %{
+              "id" => "call-count-posts",
+              "name" => "count_posts",
+              "arguments" => %{"groupBy" => ["month"], "year" => 2026}
+            }
+          ]),
+        created_at: now + 1
+      })
+    )
+
+    Repo.insert!(
+      BDS.AI.ChatMessage.changeset(%BDS.AI.ChatMessage{}, %{
+        conversation_id: conversation.id,
+        role: :tool,
+        tool_call_id: "call-count-posts",
+        content: Jason.encode!([%{"month" => 5, "count" => 3}]),
+        created_at: now + 2
+      })
+    )
+
+    Repo.insert!(
+      BDS.AI.ChatMessage.changeset(%BDS.AI.ChatMessage{}, %{
+        conversation_id: conversation.id,
+        role: :assistant,
+        content: "Here is the chart.",
+        created_at: now + 3
+      })
+    )
+
+    {:ok, view, _html} = live_isolated(build_conn(), BDS.Desktop.ShellLive)
+
+    html =
+      render_click(view, "pin_sidebar_item", %{
+        "route" => "chat",
+        "id" => conversation.id,
+        "title" => conversation.title,
+        "subtitle" => conversation.model || "chat"
+      })
+
+    assert html =~ "count_posts"
+    assert html =~ "Here is the chart."
+    assert html =~ ~s(<span class="chat-message-role">Assistant</span>)
+
+    assert length(:binary.matches(html, ~s(<span class="chat-message-role">Assistant</span>))) == 1
+  end
+
   test "chat editor marks user message text as compact" do
     assert {:ok, conversation} = AI.start_chat(%{title: "Compact Chat", model: "gpt-4.1"})