open-swe/agent/middleware/ensure_no_empty_msg.py

from typing import Any
from uuid import uuid4

from langchain.agents.middleware import AgentState, after_model
from langchain_core.messages import AnyMessage, ToolMessage
from langgraph.config import get_config
from langgraph.runtime import Runtime

from .check_message_queue import DASHBOARD_HANDOFF_MARKER

_DASHBOARD_SOURCE = "dashboard"


def get_every_message_since_last_human(state: AgentState) -> list[AnyMessage]:
    messages = state["messages"]
    last_human_idx = -1
    for i in range(len(messages) - 1, -1, -1):
        if messages[i].type == "human":
            last_human_idx = i
            break
    return messages[last_human_idx + 1 :]


def check_if_model_messaged_user(messages: list[AnyMessage]) -> bool:
    for msg in messages:
        if msg.type == "tool" and msg.name in [
            "slack_thread_reply",
            "linear_comment",
        ]:
            return True
    return False


def check_if_confirming_completion(messages: list[AnyMessage]) -> bool:
    for msg in messages:
        if msg.type == "tool" and msg.name == "confirming_completion":
            return True
    return False


def check_if_no_op(messages: list[AnyMessage]) -> bool:
    for msg in messages:
        if msg.type == "tool" and msg.name == "no_op":
            return True
    return False


def _content_contains_text(content: object, text: str) -> bool:
    if isinstance(content, str):
        return text in content
    if not isinstance(content, list):
        return False
    for block in content:
        if isinstance(block, dict) and text in str(block.get("text", "")):
            return True
    return False


def _last_human_is_dashboard_handoff(state: AgentState) -> bool:
    for msg in reversed(state["messages"]):
        if msg.type == "human":
            return _content_contains_text(msg.content, DASHBOARD_HANDOFF_MARKER)
    return False


def _is_dashboard_source() -> bool:
    try:
        config = get_config()
    except RuntimeError:
        return False
    configurable = config.get("configurable", {})
    if not isinstance(configurable, dict):
        return False
    return configurable.get("source") == _DASHBOARD_SOURCE


@after_model
def ensure_no_empty_msg(state: AgentState, runtime: Runtime) -> dict[str, Any] | None:
    last_msg = state["messages"][-1]
    has_contents = bool(last_msg.text())
    has_tool_calls = bool(last_msg.tool_calls)
    if not has_tool_calls and not has_contents:
        messages_since_last_human = get_every_message_since_last_human(state)
        if check_if_no_op(messages_since_last_human):
            return None

        if check_if_model_messaged_user(messages_since_last_human):
            return None

        tc_id = str(uuid4())
        last_msg.tool_calls = [{"name": "no_op", "args": {}, "id": tc_id}]
        no_op_tool_msg = ToolMessage(
            content="No operation performed."
            + "Please continue with the task, ensuring you ALWAYS call at least one tool in"
            + " every message unless you are absolutely sure the task has been fully completed.",
            tool_call_id=tc_id,
        )

        return {"messages": [last_msg, no_op_tool_msg]}

    if has_contents and not has_tool_calls:
        messages_since_last_human = get_every_message_since_last_human(state)

        if (
            check_if_model_messaged_user(messages_since_last_human)
            or check_if_confirming_completion(messages_since_last_human)
            or _is_dashboard_source()
            or _last_human_is_dashboard_handoff(state)
        ):
            return None

        tc_id = str(uuid4())
        last_msg.tool_calls = [{"name": "confirming_completion", "args": {}, "id": tc_id}]
        no_op_tool_msg = ToolMessage(
            content="Confirming task completion. I see you did not call a tool, which would end the task, however you haven't called a tool to message the user or open a pull request."
            + "This may indicate premature termination - please ensure you fully complete the task before ending it. "
            + "If you do not call any tools it will end the task.",
            name="confirming_completion",
            tool_call_id=tc_id,
        )

        return {"messages": [last_msg, no_op_tool_msg]}

    return None