Add separator banners to TOOL USE, AGENT START, and ERROR events

src/strands_compose/renderers/ansi.py

@@ -67,6 +67,7 @@ def __init__(
         self._green = "\033[32m" if is_tty else ""
         self._red = "\033[31m" if is_tty else ""
         self._yellow = "\033[33m" if is_tty else ""
+        self._magenta = "\033[95m" if is_tty else ""
         self._reset = "\033[0m" if is_tty else ""
 
         if separator_width is not None:
@@ -120,16 +121,19 @@ def _handle_agent_start(self, event: StreamEvent) -> None:
         self._break()
         self._mode = None
         self._active_agent = None
-        self._out.write(f"\n{self._cyan}{self._bold}[{event.agent_name}]{self._reset} starting…\n")
+        self._out.write(self._separator(event.agent_name, "AGENT START", color=self._magenta))
+        self._out.write(f"{self._cyan}{self._bold}[{event.agent_name}]{self._reset} starting…\n")
         self._out.flush()
 
     def _handle_tool_start(self, event: StreamEvent) -> None:
         self._break()
         self._mode = None
+        self._active_agent = None
         data = event.data
         label = data.get("tool_label") or data.get("tool_name", "unknown")
         tool_input = data.get("tool_input", {})
         preview = str(tool_input)[:80] + ("…" if len(str(tool_input)) > 80 else "")
+        self._out.write(self._separator(event.agent_name, "TOOL USE", color=self._magenta))
         self._out.write(
             f"  {self._yellow}⚙{self._reset}  [{event.agent_name}] -> {label!r}"
             f"  {self._dim}{preview}{self._reset}\n"
@@ -164,6 +168,7 @@ def _handle_complete(self, event: StreamEvent) -> None:
     def _handle_error(self, event: StreamEvent) -> None:
         self._break()
         self._mode = None
+        self._out.write(self._separator(event.agent_name, "ERROR", color=self._red))
         msg = event.data.get("message", "unknown error")
         exc_type = event.data.get("exception_type")
         if exc_type and msg.startswith(f"{exc_type}: "):

tests/unit/renderers/test_ansi.py

@@ -66,15 +66,18 @@ def test_agent_start_breaks_token_stream(self) -> None:
     def test_agent_start(self) -> None:
         r, buf = self._renderer()
         r.render(_event(EventType.AGENT_START))
-        assert AGENT in buf.getvalue()
-        assert "starting" in buf.getvalue()
+        output = buf.getvalue()
+        assert AGENT in output
+        assert "starting" in output
+        assert "AGENT START" in output
 
     def test_tool_start(self) -> None:
         r, buf = self._renderer()
         r.render(_event(EventType.TOOL_START, tool_name="search", tool_input={"q": "x"}))
         output = buf.getvalue()
         assert "search" in output
         assert "⚙" in output
+        assert "TOOL USE" in output
 
     def test_tool_end_success(self) -> None:
         r, buf = self._renderer()
@@ -103,6 +106,14 @@ def test_error(self) -> None:
         assert "ERROR" in output
         assert "something broke" in output
 
+    def test_error_separator_appears_before_detail(self) -> None:
+        r, buf = self._renderer()
+        r.render(_event(EventType.ERROR, message="something broke"))
+        output = buf.getvalue()
+        separator_idx = output.index("ERROR")
+        detail_idx = output.index("something broke")
+        assert separator_idx < detail_idx
+
     def test_node_start(self) -> None:
         r, buf = self._renderer()
         r.render(_event(EventType.NODE_START, node_id="n1"))