Handoff termination and show how to use it for asking user input (#4128)

* Handoff termination and show how to use it for asking user input

* lint

python/packages/autogen-agentchat/src/autogen_agentchat/task/__init__.py

@@ -1,10 +1,17 @@
 from ._console import Console
-from ._terminations import MaxMessageTermination, StopMessageTermination, TextMentionTermination, TokenUsageTermination
+from ._terminations import (
+    HandoffTermination,
+    MaxMessageTermination,
+    StopMessageTermination,
+    TextMentionTermination,
+    TokenUsageTermination,
+)
 
 __all__ = [
     "MaxMessageTermination",
     "TextMentionTermination",
     "StopMessageTermination",
     "TokenUsageTermination",
+    "HandoffTermination",
     "Console",
 ]

python/packages/autogen-agentchat/src/autogen_agentchat/task/_terminations.py

@@ -1,7 +1,7 @@
 from typing import Sequence
 
 from ..base import TerminatedException, TerminationCondition
-from ..messages import AgentMessage, MultiModalMessage, StopMessage, TextMessage
+from ..messages import AgentMessage, HandoffMessage, MultiModalMessage, StopMessage, TextMessage
 
 
 class StopMessageTermination(TerminationCondition):
@@ -144,3 +144,34 @@ class TokenUsageTermination(TerminationCondition):
         self._total_token_count = 0
         self._prompt_token_count = 0
         self._completion_token_count = 0
+
+
+class HandoffTermination(TerminationCondition):
+    """Terminate the conversation if a :class:`~autogen_agentchat.messages.HandoffMessage`
+    with the given target is received.
+
+    Args:
+        target (str): The target of the handoff message.
+    """
+
+    def __init__(self, target: str) -> None:
+        self._terminated = False
+        self._target = target
+
+    @property
+    def terminated(self) -> bool:
+        return self._terminated
+
+    async def __call__(self, messages: Sequence[AgentMessage]) -> StopMessage | None:
+        if self._terminated:
+            raise TerminatedException("Termination condition has already been reached")
+        for message in messages:
+            if isinstance(message, HandoffMessage) and message.target == self._target:
+                self._terminated = True
+                return StopMessage(
+                    content=f"Handoff to {self._target} from {message.source} detected.", source="HandoffTermination"
+                )
+        return None
+
+    async def reset(self) -> None:
+        self._terminated = False

python/packages/autogen-agentchat/tests/test_termination_condition.py

@@ -1,6 +1,7 @@
 import pytest
-from autogen_agentchat.messages import StopMessage, TextMessage
+from autogen_agentchat.messages import HandoffMessage, StopMessage, TextMessage
 from autogen_agentchat.task import (
+    HandoffTermination,
     MaxMessageTermination,
     StopMessageTermination,
     TextMentionTermination,
@@ -9,6 +10,32 @@ from autogen_agentchat.task import (
 from autogen_core.components.models import RequestUsage
 
 
+@pytest.mark.asyncio
+async def test_handoff_termination() -> None:
+    termination = HandoffTermination("target")
+    assert await termination([]) is None
+    await termination.reset()
+    assert await termination([TextMessage(content="Hello", source="user")]) is None
+    await termination.reset()
+    assert await termination([HandoffMessage(target="target", source="user", content="Hello")]) is not None
+    assert termination.terminated
+    await termination.reset()
+    assert await termination([HandoffMessage(target="another", source="user", content="Hello")]) is None
+    assert not termination.terminated
+    await termination.reset()
+    assert (
+        await termination(
+            [
+                TextMessage(content="Hello", source="user"),
+                HandoffMessage(target="target", source="user", content="Hello"),
+            ]
+        )
+        is not None
+    )
+    assert termination.terminated
+    await termination.reset()
+
+
 @pytest.mark.asyncio
 async def test_stop_message_termination() -> None:
     termination = StopMessageTermination()

python/packages/autogen-core/docs/src/user-guide/agentchat-user-guide/tutorial/teams.ipynb

@@ -49,7 +49,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 7,
+   "execution_count": 2,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -404,8 +404,6 @@
     }
    ],
    "source": [
-    "from autogen_agentchat.task import Console\n",
-    "\n",
     "# Use `asyncio.run(Console(reflection_team.run_stream(task=\"Write a short poem about fall season.\")))` when running in a script.\n",
     "await Console(\n",
     "    reflection_team.run_stream(task=\"Write a short poem about fall season.\")\n",
@@ -593,6 +591,141 @@
     "# Use the `asyncio.run(Console(reflection_team.run_stream()))` when running in a script.\n",
     "await Console(reflection_team.run_stream())"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Pause for User Input\n",
+    "\n",
+    "Often times, team needs additional input from the application (i.e., user)\n",
+    "to continue processing the task.\n",
+    "You can use the {py:class}`~autogen_agentchat.task.HandoffTermination` termination condition\n",
+    "to stop the team when an agent sends a {py:class}`~autogen_agentchat.messages.HandoffMessage` message.\n",
+    "\n",
+    "Let's create a team with a single {py:class}`~autogen_agentchat.agents.AssistantAgent` agent\n",
+    "with a handoff setting.\n",
+    "\n",
+    "```{note}\n",
+    "The model used with {py:class}`~autogen_agentchat.agents.AssistantAgent`must support tool call\n",
+    "to use the handoff feature.\n",
+    "```"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 15,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from autogen_agentchat.agents import AssistantAgent, Handoff\n",
+    "from autogen_agentchat.task import HandoffTermination, TextMentionTermination\n",
+    "from autogen_agentchat.teams import RoundRobinGroupChat\n",
+    "from autogen_ext.models import OpenAIChatCompletionClient\n",
+    "\n",
+    "# Create an OpenAI model client.\n",
+    "model_client = OpenAIChatCompletionClient(\n",
+    "    model=\"gpt-4o-2024-08-06\",\n",
+    "    # api_key=\"sk-...\", # Optional if you have an OPENAI_API_KEY env variable set.\n",
+    ")\n",
+    "\n",
+    "# Create a lazy assistant agent that always hands off to the user.\n",
+    "lazy_agent = AssistantAgent(\n",
+    "    \"lazy_assistant\",\n",
+    "    model_client=model_client,\n",
+    "    handoffs=[Handoff(target=\"user\", message=\"Transfer to user.\")],\n",
+    "    system_message=\"Always transfer to user when you don't know the answer. Respond 'TERMINATE' when task is complete.\",\n",
+    ")\n",
+    "\n",
+    "# Define a termination condition that checks for handoff message targetting helper and text \"TERMINATE\".\n",
+    "handoff_termination = HandoffTermination(target=\"user\")\n",
+    "text_termination = TextMentionTermination(\"TERMINATE\")\n",
+    "termination = handoff_termination | text_termination\n",
+    "\n",
+    "# Create a single-agent team.\n",
+    "lazy_agent_team = RoundRobinGroupChat([lazy_agent], termination_condition=termination)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Let's run the team with a task that requires additional input from the user\n",
+    "because the agent doesn't have relevant tools to continue processing the task."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 16,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "---------- user ----------\n",
+      "What is the weather in New York?\n",
+      "---------- lazy_assistant ----------\n",
+      "[FunctionCall(id='call_YHm4KPjFIWZE95YrJWlJwcv4', arguments='{}', name='transfer_to_user')]\n",
+      "[Prompt tokens: 68, Completion tokens: 11]\n",
+      "---------- lazy_assistant ----------\n",
+      "[FunctionExecutionResult(content='Transfer to user.', call_id='call_YHm4KPjFIWZE95YrJWlJwcv4')]\n",
+      "---------- lazy_assistant ----------\n",
+      "Transfer to user.\n",
+      "---------- Summary ----------\n",
+      "Number of messages: 4\n",
+      "Finish reason: Handoff to user from lazy_assistant detected.\n",
+      "Total prompt tokens: 68\n",
+      "Total completion tokens: 11\n",
+      "Duration: 0.73 seconds\n"
+     ]
+    }
+   ],
+   "source": [
+    "from autogen_agentchat.task import Console\n",
+    "\n",
+    "# Use `asyncio.run(Console(lazy_agent_team.run_stream(task=\"What is the weather in New York?\")))` when running in a script.\n",
+    "await Console(lazy_agent_team.run_stream(task=\"What is the weather in New York?\"))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "You can see the team stopped due to the handoff message was detected.\n",
+    "Let's continue the team by providing the information the agent needs."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 17,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "---------- user ----------\n",
+      "It is raining in New York.\n",
+      "---------- lazy_assistant ----------\n",
+      "I hope you stay dry! Is there anything else you would like to know or do?\n",
+      "[Prompt tokens: 108, Completion tokens: 19]\n",
+      "---------- lazy_assistant ----------\n",
+      "TERMINATE\n",
+      "[Prompt tokens: 134, Completion tokens: 4]\n",
+      "---------- Summary ----------\n",
+      "Number of messages: 3\n",
+      "Finish reason: Text 'TERMINATE' mentioned\n",
+      "Total prompt tokens: 242\n",
+      "Total completion tokens: 23\n",
+      "Duration: 6.77 seconds\n"
+     ]
+    }
+   ],
+   "source": [
+    "# Use `asyncio.run(Console(lazy_agent_team.run_stream(task=\"It is raining in New York.\")))` when running in a script.\n",
+    "await Console(lazy_agent_team.run_stream(task=\"It is raining in New York.\"))"
+   ]
   }
  ],
  "metadata": {