chendandan_homework/app/graph/travel_builder.py

from __future__ import annotations
"""资源查询阶段子图：在需求解析后调用航班/酒店MCP工具查询外部资源。"""

from langgraph.graph import (
    END,
    START,
    StateGraph,
)

from app.agents.requirement_agent import (
    RequirementAgent,
)
from app.agents.resource_agent import (
    ResourceSearchAgent,
)
from app.graph.nodes import (
    clarification_node,
    error_node,
    make_parse_request_node,
    route_after_parse,
)
from app.graph.resource_nodes import (
    make_resource_search_node,
)
from app.graph.state import TravelState
from app.mcp_client import load_mcp_tools


async def build_resource_graph():
    """构建需求解析与资源查询工作流。"""

    tool_bundle = await load_mcp_tools()

    requirement_agent = RequirementAgent()

    resource_agent = ResourceSearchAgent(
        tools=tool_bundle.travel_tools,
    )

    builder = StateGraph(TravelState)

    builder.add_node(
        "parse_request",
        make_parse_request_node(
            requirement_agent
        ),
    )

    builder.add_node(
        "clarify",
        clarification_node,
    )

    builder.add_node(
        "error",
        error_node,
    )

    builder.add_node(
        "search_resources",
        make_resource_search_node(
            resource_agent
        ),
    )

    builder.add_edge(
        START,
        "parse_request",
    )

    builder.add_conditional_edges(
        "parse_request",
        route_after_parse,
        {
            "clarify": "clarify",
            "error": "error",
            "ready": "search_resources",
        },
    )

    builder.add_edge(
        "clarify",
        END,
    )

    builder.add_edge(
        "error",
        END,
    )

    builder.add_edge(
        "search_resources",
        END,
    )

    return builder.compile()