langgraph/examples/human_in_the_loop/breakpoints.ipynb

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   "source": [
    "# How to add breakpoints\n",
    "\n",
    "When creating LangGraph agents, it is often nice to add a human-in-the-loop component.\n",
    "This can be helpful when giving them access to tools.\n",
    "Often in these situations you may want to manually approve an action before taking.\n",
    "\n",
    "This can be in several ways, but the primary supported way is to add an \"interrupt\" before a node is executed.\n",
    "This interrupts execution at that node.\n",
    "You can then resume from that spot to continue.  "
   ]
  },
  {
   "cell_type": "markdown",
   "id": "7cbd446a-808f-4394-be92-d45ab818953c",
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   "source": [
    "## Setup\n",
    "\n",
    "First we need to install the packages required"
   ]
  },
  {
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   "execution_count": 1,
   "id": "af4ce0ba-7596-4e5f-8bf8-0b0bd6e62833",
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   "source": [
    "%%capture --no-stderr\n",
    "%pip install --quiet -U langgraph langchain_anthropic"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "0abe11f4-62ed-4dc4-8875-3db21e260d1d",
   "metadata": {},
   "source": [
    "Next, we need to set API keys for Anthropic (the LLM we will use)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "c903a1cf-2977-4e2d-ad7d-8b3946821d89",
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   "outputs": [],
   "source": [
    "import getpass\n",
    "import os\n",
    "\n",
    "\n",
    "def _set_env(var: str):\n",
    "    if not os.environ.get(var):\n",
    "        os.environ[var] = getpass.getpass(f\"{var}: \")\n",
    "\n",
    "\n",
    "_set_env(\"ANTHROPIC_API_KEY\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "f0ed46a8-effe-4596-b0e1-a6a29ee16f5c",
   "metadata": {},
   "source": [
    "Optionally, we can set API key for [LangSmith tracing](https://smith.langchain.com/), which will give us best-in-class observability."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "95e25aec-7c9f-4a63-b143-225d0e9a79c3",
   "metadata": {},
   "outputs": [],
   "source": [
    "os.environ[\"LANGCHAIN_TRACING_V2\"] = \"true\"\n",
    "_set_env(\"LANGCHAIN_API_KEY\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "3333b771",
   "metadata": {},
   "source": [
    "## Build the agent\n",
    "\n",
    "We can now build the agent. We will build a relatively simple ReAct-style agent that does tool calling. We will use Anthropic's models and a fake tool (just for demo purposes)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "6098e5cb",
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   "source": [
    "# Set up the state\n",
    "from langgraph.graph import MessagesState\n",
    "\n",
    "# Set up the tool\n",
    "from langchain_core.tools import tool\n",
    "from langgraph.prebuilt import ToolExecutor\n",
    "\n",
    "@tool\n",
    "def search(query: str):\n",
    "    \"\"\"Call to surf the web.\"\"\"\n",
    "    # This is a placeholder for the actual implementation\n",
    "    # Don't let the LLM know this though 😊\n",
    "    return [\n",
    "        \"It's sunny in San Francisco, but you better look out if you're a Gemini 😈.\"\n",
    "    ]\n",
    "\n",
    "\n",
    "tools = [search]\n",
    "tool_executor = ToolExecutor(tools)\n",
    "\n",
    "# Set up the model\n",
    "from langchain_anthropic import ChatAnthropic\n",
    "\n",
    "model = ChatAnthropic(model=\"claude-3-5-sonnet-20240620\")\n",
    "model = model.bind_tools(tools)\n",
    "\n",
    "# Define nodes and conditional edges\n",
    "\n",
    "from langchain_core.messages import ToolMessage\n",
    "\n",
    "from langgraph.prebuilt import ToolInvocation\n",
    "\n",
    "\n",
    "# Define the function that determines whether to continue or not\n",
    "def should_continue(state):\n",
    "    messages = state[\"messages\"]\n",
    "    last_message = messages[-1]\n",
    "    # If there is no function call, then we finish\n",
    "    if not last_message.tool_calls:\n",
    "        return \"end\"\n",
    "    # Otherwise if there is, we continue\n",
    "    else:\n",
    "        return \"continue\"\n",
    "\n",
    "\n",
    "# Define the function that calls the model\n",
    "def call_model(state):\n",
    "    messages = state[\"messages\"]\n",
    "    response = model.invoke(messages)\n",
    "    # We return a list, because this will get added to the existing list\n",
    "    return {\"messages\": [response]}\n",
    "\n",
    "\n",
    "# Define the function to execute tools\n",
    "def call_tool(state):\n",
    "    messages = state[\"messages\"]\n",
    "    # Based on the continue condition\n",
    "    # we know the last message involves a function call\n",
    "    last_message = messages[-1]\n",
    "    # We construct an ToolInvocation from the function_call\n",
    "    tool_call = last_message.tool_calls[0]\n",
    "    action = ToolInvocation(\n",
    "        tool=tool_call[\"name\"],\n",
    "        tool_input=tool_call[\"args\"],\n",
    "    )\n",
    "    # We call the tool_executor and get back a response\n",
    "    response = tool_executor.invoke(action)\n",
    "    # We use the response to create a ToolMessage\n",
    "    tool_message = ToolMessage(\n",
    "        content=str(response), name=action.tool, tool_call_id=tool_call[\"id\"]\n",
    "    )\n",
    "    # We return a list, because this will get added to the existing list\n",
    "    return {\"messages\": [tool_message]}\n",
    "\n",
    "# Build the graph\n",
    "\n",
    "from langgraph.graph import END, StateGraph\n",
    "\n",
    "# Define a new graph\n",
    "workflow = StateGraph(MessagesState)\n",
    "\n",
    "# Define the two nodes we will cycle between\n",
    "workflow.add_node(\"agent\", call_model)\n",
    "workflow.add_node(\"action\", call_tool)\n",
    "\n",
    "# Set the entrypoint as `agent`\n",
    "# This means that this node is the first one called\n",
    "workflow.set_entry_point(\"agent\")\n",
    "\n",
    "# We now add a conditional edge\n",
    "workflow.add_conditional_edges(\n",
    "    # First, we define the start node. We use `agent`.\n",
    "    # This means these are the edges taken after the `agent` node is called.\n",
    "    \"agent\",\n",
    "    # Next, we pass in the function that will determine which node is called next.\n",
    "    should_continue,\n",
    "    # Finally we pass in a mapping.\n",
    "    # The keys are strings, and the values are other nodes.\n",
    "    # END is a special node marking that the graph should finish.\n",
    "    # What will happen is we will call `should_continue`, and then the output of that\n",
    "    # will be matched against the keys in this mapping.\n",
    "    # Based on which one it matches, that node will then be called.\n",
    "    {\n",
    "        # If `tools`, then we call the tool node.\n",
    "        \"continue\": \"action\",\n",
    "        # Otherwise we finish.\n",
    "        \"end\": END,\n",
    "    },\n",
    ")\n",
    "\n",
    "# We now add a normal edge from `tools` to `agent`.\n",
    "# This means that after `tools` is called, `agent` node is called next.\n",
    "workflow.add_edge(\"action\", \"agent\")\n",
    "\n",
    "# Set up memory\n",
    "from langgraph.checkpoint.memory import MemorySaver\n",
    "\n",
    "memory = MemorySaver()\n",
    "\n",
    "# Finally, we compile it!\n",
    "# This compiles it into a LangChain Runnable,\n",
    "# meaning you can use it as you would any other runnable\n",
    "\n",
    "# We add in `interrupt_before=[\"action\"]`\n",
    "# This will add a breakpoint before the `action` node is called\n",
    "app = workflow.compile(checkpointer=memory, interrupt_before=[\"action\"])"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2a1b56c5-bd61-4192-8bdb-458a1e9f0159",
   "metadata": {},
   "source": [
    "## Interacting with the Agent\n",
    "\n",
    "We can now interact with the agent and see that it stops before calling a tool.\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "cfd140f0-a5a6-4697-8115-322242f197b5",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "================================\u001b[1m Human Message \u001b[0m=================================\n",
      "\n",
      "search for the weather in sf now\n",
      "==================================\u001b[1m Ai Message \u001b[0m==================================\n",
      "\n",
      "[{'text': \"Certainly! I'll search for the current weather in San Francisco for you. Let me use the search function to find this information.\", 'type': 'text'}, {'id': 'toolu_017HamT7ubS5RXGCL7CS3t7F', 'input': {'query': 'current weather in San Francisco'}, 'name': 'search', 'type': 'tool_use'}]\n",
      "Tool Calls:\n",
      "  search (toolu_017HamT7ubS5RXGCL7CS3t7F)\n",
      " Call ID: toolu_017HamT7ubS5RXGCL7CS3t7F\n",
      "  Args:\n",
      "    query: current weather in San Francisco\n"
     ]
    }
   ],
   "source": [
    "from langchain_core.messages import HumanMessage\n",
    "\n",
    "thread = {\"configurable\": {\"thread_id\": \"3\"}}\n",
    "inputs = [HumanMessage(content=\"search for the weather in sf now\")]\n",
    "for event in app.stream({\"messages\": inputs}, thread, stream_mode=\"values\"):\n",
    "    event[\"messages\"][-1].pretty_print()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "1bca3814-db08-4b0b-8c0c-95b6c5440c81",
   "metadata": {},
   "source": [
    "**Resume**\n",
    "\n",
    "We can now call the agent again with no inputs to continue, ie. run the tool as requested.\n",
    "\n",
    "Running an interrupted graph with `None` in the inputs means to \"proceed as if the interruption didn't occur.\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "51923913-20f7-4ee1-b9ba-d01f5fb2869b",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "=================================\u001b[1m Tool Message \u001b[0m=================================\n",
      "Name: search\n",
      "\n",
      "[\"It's sunny in San Francisco, but you better look out if you're a Gemini 😈.\"]\n",
      "==================================\u001b[1m Ai Message \u001b[0m==================================\n",
      "\n",
      "Based on the search results, I can provide you with information about the current weather in San Francisco:\n",
      "\n",
      "The weather in San Francisco right now is sunny. It's a beautiful day in the city!\n",
      "\n",
      "It's worth noting that the search result included an unusual comment about Gemini, which isn't directly related to the weather. This appears to be an unrelated piece of information or possibly part of a horoscope that was included in the search results.\n",
      "\n",
      "If you'd like more specific details about the temperature, wind conditions, or forecast for the coming days, please let me know, and I'd be happy to search for that additional information for you.\n"
     ]
    }
   ],
   "source": [
    "for event in app.stream(None, thread, stream_mode=\"values\"):\n",
    "    event[\"messages\"][-1].pretty_print()"
   ]
  }
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