diff --git a/nanobot/agent/loop.py b/nanobot/agent/loop.py
index 9128b8840..54bb29c5d 100644
--- a/nanobot/agent/loop.py
+++ b/nanobot/agent/loop.py
@@ -308,7 +308,7 @@ class AgentLoop:
         channel: str = "cli",
         chat_id: str = "direct",
         message_id: str | None = None,
-    ) -> tuple[str | None, list[str], list[dict]]:
+    ) -> tuple[str | None, list[str], list[dict], str]:
         """Run the agent iteration loop.
 
         *on_stream*: called with each content delta during streaming.
@@ -358,7 +358,7 @@ class AgentLoop:
             logger.warning("Max iterations ({}) reached", self.max_iterations)
         elif result.stop_reason == "error":
             logger.error("LLM returned error: {}", (result.final_content or "")[:200])
-        return result.final_content, result.tools_used, result.messages
+        return result.final_content, result.tools_used, result.messages, result.stop_reason
 
     async def run(self) -> None:
         """Run the agent loop, dispatching messages as tasks to stay responsive to /stop."""
@@ -505,7 +505,7 @@ class AgentLoop:
                 current_message=msg.content, channel=channel, chat_id=chat_id,
                 current_role=current_role,
             )
-            final_content, _, all_msgs = await self._run_agent_loop(
+            final_content, _, all_msgs, _ = await self._run_agent_loop(
                 messages, session=session, channel=channel, chat_id=chat_id,
                 message_id=msg.metadata.get("message_id"),
             )
@@ -553,7 +553,7 @@ class AgentLoop:
                 channel=msg.channel, chat_id=msg.chat_id, content=content, metadata=meta,
             ))
 
-        final_content, _, all_msgs = await self._run_agent_loop(
+        final_content, _, all_msgs, stop_reason = await self._run_agent_loop(
             initial_messages,
             on_progress=on_progress or _bus_progress,
             on_stream=on_stream,
@@ -578,7 +578,7 @@ class AgentLoop:
         logger.info("Response to {}:{}: {}", msg.channel, msg.sender_id, preview)
 
         meta = dict(msg.metadata or {})
-        if on_stream is not None:
+        if on_stream is not None and stop_reason != "error":
             meta["_streamed"] = True
         return OutboundMessage(
             channel=msg.channel, chat_id=msg.chat_id, content=final_content,
diff --git a/nanobot/agent/runner.py b/nanobot/agent/runner.py
index abc7edf09..bc1a26aba 100644
--- a/nanobot/agent/runner.py
+++ b/nanobot/agent/runner.py
@@ -257,7 +257,6 @@ class AgentRunner:
                 final_content = clean or spec.error_message or _DEFAULT_ERROR_MESSAGE
                 stop_reason = "error"
                 error = final_content
-                self._append_final_message(messages, final_content)
                 context.final_content = final_content
                 context.error = error
                 context.stop_reason = stop_reason
diff --git a/tests/agent/test_hook_composite.py b/tests/agent/test_hook_composite.py
index c6077d526..672f38ed2 100644
--- a/tests/agent/test_hook_composite.py
+++ b/tests/agent/test_hook_composite.py
@@ -307,7 +307,7 @@ async def test_agent_loop_extra_hook_receives_calls(tmp_path):
     )
     loop.tools.get_definitions = MagicMock(return_value=[])
 
-    content, tools_used, messages = await loop._run_agent_loop(
+    content, tools_used, messages, _ = await loop._run_agent_loop(
         [{"role": "user", "content": "hi"}]
     )
 
@@ -331,7 +331,7 @@ async def test_agent_loop_extra_hook_error_isolation(tmp_path):
     )
     loop.tools.get_definitions = MagicMock(return_value=[])
 
-    content, _, _ = await loop._run_agent_loop(
+    content, _, _, _ = await loop._run_agent_loop(
         [{"role": "user", "content": "hi"}]
     )
 
@@ -373,7 +373,7 @@ async def test_agent_loop_no_hooks_backward_compat(tmp_path):
     loop.tools.execute = AsyncMock(return_value="ok")
     loop.max_iterations = 2
 
-    content, tools_used, _ = await loop._run_agent_loop([])
+    content, tools_used, _, _ = await loop._run_agent_loop([])
     assert content == (
         "I reached the maximum number of tool call iterations (2) "
         "without completing the task. You can try breaking the task into smaller steps."
diff --git a/tests/agent/test_runner.py b/tests/agent/test_runner.py
index a0804396e..36d5de846 100644
--- a/tests/agent/test_runner.py
+++ b/tests/agent/test_runner.py
@@ -798,7 +798,7 @@ async def test_loop_max_iterations_message_stays_stable(tmp_path):
     loop.tools.execute = AsyncMock(return_value="ok")
     loop.max_iterations = 2
 
-    final_content, _, _ = await loop._run_agent_loop([])
+    final_content, _, _, _ = await loop._run_agent_loop([])
 
     assert final_content == (
         "I reached the maximum number of tool call iterations (2) "
@@ -825,7 +825,7 @@ async def test_loop_stream_filter_handles_think_only_prefix_without_crashing(tmp
     async def on_stream_end(*, resuming: bool = False) -> None:
         endings.append(resuming)
 
-    final_content, _, _ = await loop._run_agent_loop(
+    final_content, _, _, _ = await loop._run_agent_loop(
         [],
         on_stream=on_stream,
         on_stream_end=on_stream_end,
@@ -849,7 +849,7 @@ async def test_loop_retries_think_only_final_response(tmp_path):
 
     loop.provider.chat_with_retry = chat_with_retry
 
-    final_content, _, _ = await loop._run_agent_loop([])
+    final_content, _, _, _ = await loop._run_agent_loop([])
 
     assert final_content == "Recovered answer"
     assert call_count["n"] == 2
diff --git a/tests/tools/test_message_tool_suppress.py b/tests/tools/test_message_tool_suppress.py
index 26d12085f..3f06b4a70 100644
--- a/tests/tools/test_message_tool_suppress.py
+++ b/tests/tools/test_message_tool_suppress.py
@@ -107,7 +107,7 @@ class TestMessageToolSuppressLogic:
         async def on_progress(content: str, *, tool_hint: bool = False) -> None:
             progress.append((content, tool_hint))
 
-        final_content, _, _ = await loop._run_agent_loop([], on_progress=on_progress)
+        final_content, _, _, _ = await loop._run_agent_loop([], on_progress=on_progress)
 
         assert final_content == "Done"
         assert progress == [