deer-flow/backend/packages/harness/deerflow/agents/middlewares/clarification_middleware.py

"""Middleware for intercepting clarification requests and presenting them to the user."""

import json
import logging
from collections.abc import Callable
from hashlib import sha256
from typing import override

from langchain.agents import AgentState
from langchain.agents.middleware import AgentMiddleware
from langchain_core.messages import ToolMessage
from langgraph.graph import END
from langgraph.prebuilt.tool_node import ToolCallRequest
from langgraph.types import Command

logger = logging.getLogger(__name__)


class ClarificationMiddlewareState(AgentState):
    """Compatible with the `ThreadState` schema."""

    pass


class ClarificationMiddleware(AgentMiddleware[ClarificationMiddlewareState]):
    """Intercepts clarification tool calls and interrupts execution to present questions to the user.

    When the model calls the `ask_clarification` tool, this middleware:
    1. Intercepts the tool call before execution
    2. Extracts the clarification question and metadata
    3. Formats a user-friendly message
    4. Returns a Command that interrupts execution and presents the question
    5. Waits for user response before continuing

    This replaces the tool-based approach where clarification continued the conversation flow.
    """

    state_schema = ClarificationMiddlewareState

    def _stable_message_id(self, tool_call_id: str, formatted_message: str) -> str:
        """Build a deterministic message ID so retried clarification calls replace, not append."""
        if tool_call_id:
            return f"clarification:{tool_call_id}"
        digest = sha256(formatted_message.encode("utf-8")).hexdigest()[:16]
        return f"clarification:{digest}"

    def _is_chinese(self, text: str) -> bool:
        """Check if text contains Chinese characters.

        Args:
            text: Text to check

        Returns:
            True if text contains Chinese characters
        """
        return any("\u4e00" <= char <= "\u9fff" for char in text)

    def _format_clarification_message(self, args: dict) -> str:
        """Format the clarification arguments into a user-friendly message.

        Args:
            args: The tool call arguments containing clarification details

        Returns:
            Formatted message string
        """
        question = args.get("question", "")
        clarification_type = args.get("clarification_type", "missing_info")
        context = args.get("context")
        options = args.get("options", [])

        # Some models (e.g. Qwen3-Max) serialize array parameters as JSON strings
        # instead of native arrays. Deserialize and normalize so `options`
        # is always a list for the rendering logic below.
        if isinstance(options, str):
            try:
                options = json.loads(options)
            except (json.JSONDecodeError, TypeError):
                options = [options]

        if options is None:
            options = []
        elif not isinstance(options, list):
            options = [options]

        # Type-specific icons
        type_icons = {
            "missing_info": "❓",
            "ambiguous_requirement": "🤔",
            "approach_choice": "🔀",
            "risk_confirmation": "⚠️",
            "suggestion": "💡",
        }

        icon = type_icons.get(clarification_type, "❓")

        # Build the message naturally
        message_parts = []

        # Add icon and question together for a more natural flow
        if context:
            # If there's context, present it first as background
            message_parts.append(f"{icon} {context}")
            message_parts.append(f"\n{question}")
        else:
            # Just the question with icon
            message_parts.append(f"{icon} {question}")

        # Add options in a cleaner format
        if options and len(options) > 0:
            message_parts.append("")  # blank line for spacing
            for i, option in enumerate(options, 1):
                message_parts.append(f"  {i}. {option}")

        return "\n".join(message_parts)

    def _is_disabled(self, request: ToolCallRequest) -> bool:
        """Whether clarifications are suppressed for this run.

        Non-interactive channels (e.g. GitHub webhooks) set
        ``disable_clarification`` in the run context because a clarification
        would dead-end the run — the human only "replies" via a later
        webhook delivery, by which point the agent's turn is long over.
        When set, we don't interrupt; we return a ToolMessage nudging the
        agent to proceed with its best judgment instead.
        """
        runtime = getattr(request, "runtime", None)
        context = getattr(runtime, "context", None)
        if not context:
            return False
        return bool(context.get("disable_clarification"))

    def _handle_disabled_clarification(self, request: ToolCallRequest) -> ToolMessage:
        """Suppress a clarification and tell the agent to proceed.

        Returns a plain ToolMessage (not a ``Command(goto=END)``) so the
        agent loop continues instead of ending — the agent receives this
        as the tool result and generates again, ideally acting rather
        than re-asking.
        """
        tool_call_id = request.tool_call.get("id", "")
        logger.info("ask_clarification suppressed (disable_clarification set); instructing agent to proceed")
        return ToolMessage(
            id=self._stable_message_id(tool_call_id, "proceed-without-clarification"),
            content=(
                "Clarification is disabled in this context — the human is not present "
                "to answer synchronously. Do not ask for confirmation. Proceed with your "
                "best judgment, carry out the requested action, and state any assumptions "
                "you made in your final response."
            ),
            tool_call_id=tool_call_id,
            name="ask_clarification",
        )

    def _handle_clarification(self, request: ToolCallRequest) -> Command:
        """Handle clarification request and return command to interrupt execution.

        Args:
            request: Tool call request

        Returns:
            Command that interrupts execution with the formatted clarification message
        """
        # Extract clarification arguments
        args = request.tool_call.get("args", {})
        question = args.get("question", "")

        logger.info("Intercepted clarification request")
        logger.debug("Clarification question: %s", question)

        # Format the clarification message
        formatted_message = self._format_clarification_message(args)

        # Get the tool call ID
        tool_call_id = request.tool_call.get("id", "")

        # Create a ToolMessage with the formatted question
        # This will be added to the message history
        tool_message = ToolMessage(
            id=self._stable_message_id(tool_call_id, formatted_message),
            content=formatted_message,
            tool_call_id=tool_call_id,
            name="ask_clarification",
        )

        # Return a Command that:
        # 1. Adds the formatted tool message
        # 2. Interrupts execution by going to __end__
        # Note: We don't add an extra AIMessage here - the frontend will detect
        # and display ask_clarification tool messages directly
        return Command(
            update={"messages": [tool_message]},
            goto=END,
        )

    @override
    def wrap_tool_call(
        self,
        request: ToolCallRequest,
        handler: Callable[[ToolCallRequest], ToolMessage | Command],
    ) -> ToolMessage | Command:
        """Intercept ask_clarification tool calls and interrupt execution (sync version).

        Args:
            request: Tool call request
            handler: Original tool execution handler

        Returns:
            Command that interrupts execution with the formatted clarification message
        """
        # Check if this is an ask_clarification tool call
        if request.tool_call.get("name") != "ask_clarification":
            # Not a clarification call, execute normally
            return handler(request)

        if self._is_disabled(request):
            return self._handle_disabled_clarification(request)

        return self._handle_clarification(request)

    @override
    async def awrap_tool_call(
        self,
        request: ToolCallRequest,
        handler: Callable[[ToolCallRequest], ToolMessage | Command],
    ) -> ToolMessage | Command:
        """Intercept ask_clarification tool calls and interrupt execution (async version).

        Args:
            request: Tool call request
            handler: Original tool execution handler (async)

        Returns:
            Command that interrupts execution with the formatted clarification message
        """
        # Check if this is an ask_clarification tool call
        if request.tool_call.get("name") != "ask_clarification":
            # Not a clarification call, execute normally
            return await handler(request)

        if self._is_disabled(request):
            return self._handle_disabled_clarification(request)

        return self._handle_clarification(request)