dify
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243
dify/api/controllers/mcp/mcp.py
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243
dify/api/controllers/mcp/mcp.py
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from typing import Union
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from flask import Response
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from flask_restx import Resource, reqparse
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from pydantic import ValidationError
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from sqlalchemy.orm import Session
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from controllers.console.app.mcp_server import AppMCPServerStatus
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from controllers.mcp import mcp_ns
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from core.app.app_config.entities import VariableEntity
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from core.mcp import types as mcp_types
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from core.mcp.server.streamable_http import handle_mcp_request
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from extensions.ext_database import db
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from libs import helper
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from models.model import App, AppMCPServer, AppMode, EndUser
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class MCPRequestError(Exception):
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"""Custom exception for MCP request processing errors"""
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def __init__(self, error_code: int, message: str):
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self.error_code = error_code
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self.message = message
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super().__init__(message)
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def int_or_str(value):
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"""Validate that a value is either an integer or string."""
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if isinstance(value, (int, str)):
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return value
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else:
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return None
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# Define parser for both documentation and validation
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mcp_request_parser = (
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reqparse.RequestParser()
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.add_argument("jsonrpc", type=str, required=True, location="json", help="JSON-RPC version (should be '2.0')")
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.add_argument("method", type=str, required=True, location="json", help="The method to invoke")
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.add_argument("params", type=dict, required=False, location="json", help="Parameters for the method")
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.add_argument("id", type=int_or_str, required=False, location="json", help="Request ID for tracking responses")
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)
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@mcp_ns.route("/server/<string:server_code>/mcp")
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class MCPAppApi(Resource):
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@mcp_ns.expect(mcp_request_parser)
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@mcp_ns.doc("handle_mcp_request")
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@mcp_ns.doc(description="Handle Model Context Protocol (MCP) requests for a specific server")
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@mcp_ns.doc(params={"server_code": "Unique identifier for the MCP server"})
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@mcp_ns.doc(
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responses={
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200: "MCP response successfully processed",
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400: "Invalid MCP request or parameters",
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404: "Server or app not found",
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}
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)
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def post(self, server_code: str):
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"""Handle MCP requests for a specific server.
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Processes JSON-RPC formatted requests according to the Model Context Protocol specification.
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Validates the server status and associated app before processing the request.
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Args:
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server_code: Unique identifier for the MCP server
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Returns:
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dict: JSON-RPC response from the MCP handler
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Raises:
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ValidationError: Invalid request format or parameters
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"""
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args = mcp_request_parser.parse_args()
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request_id: Union[int, str] | None = args.get("id")
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mcp_request = self._parse_mcp_request(args)
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with Session(db.engine, expire_on_commit=False) as session:
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# Get MCP server and app
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mcp_server, app = self._get_mcp_server_and_app(server_code, session)
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self._validate_server_status(mcp_server)
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# Get user input form
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user_input_form = self._get_user_input_form(app)
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# Handle notification vs request differently
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return self._process_mcp_message(mcp_request, request_id, app, mcp_server, user_input_form, session)
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def _get_mcp_server_and_app(self, server_code: str, session: Session) -> tuple[AppMCPServer, App]:
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"""Get and validate MCP server and app in one query session"""
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mcp_server = session.query(AppMCPServer).where(AppMCPServer.server_code == server_code).first()
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if not mcp_server:
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raise MCPRequestError(mcp_types.INVALID_REQUEST, "Server Not Found")
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app = session.query(App).where(App.id == mcp_server.app_id).first()
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if not app:
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raise MCPRequestError(mcp_types.INVALID_REQUEST, "App Not Found")
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return mcp_server, app
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def _validate_server_status(self, mcp_server: AppMCPServer):
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"""Validate MCP server status"""
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if mcp_server.status != AppMCPServerStatus.ACTIVE:
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raise MCPRequestError(mcp_types.INVALID_REQUEST, "Server is not active")
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def _process_mcp_message(
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self,
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mcp_request: mcp_types.ClientRequest | mcp_types.ClientNotification,
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request_id: Union[int, str] | None,
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app: App,
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mcp_server: AppMCPServer,
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user_input_form: list[VariableEntity],
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session: Session,
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) -> Response:
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"""Process MCP message (notification or request)"""
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if isinstance(mcp_request, mcp_types.ClientNotification):
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return self._handle_notification(mcp_request)
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else:
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return self._handle_request(mcp_request, request_id, app, mcp_server, user_input_form, session)
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def _handle_notification(self, mcp_request: mcp_types.ClientNotification) -> Response:
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"""Handle MCP notification"""
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# For notifications, only support init notification
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if mcp_request.root.method != "notifications/initialized":
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raise MCPRequestError(mcp_types.INVALID_REQUEST, "Invalid notification method")
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# Return HTTP 202 Accepted for notifications (no response body)
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return Response("", status=202, content_type="application/json")
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def _handle_request(
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self,
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mcp_request: mcp_types.ClientRequest,
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request_id: Union[int, str] | None,
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app: App,
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mcp_server: AppMCPServer,
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user_input_form: list[VariableEntity],
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session: Session,
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) -> Response:
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"""Handle MCP request"""
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if request_id is None:
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raise MCPRequestError(mcp_types.INVALID_REQUEST, "Request ID is required")
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result = self._handle_mcp_request(app, mcp_server, mcp_request, user_input_form, session, request_id)
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if result is None:
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# This shouldn't happen for requests, but handle gracefully
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raise MCPRequestError(mcp_types.INTERNAL_ERROR, "No response generated for request")
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return helper.compact_generate_response(result.model_dump(by_alias=True, mode="json", exclude_none=True))
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def _get_user_input_form(self, app: App) -> list[VariableEntity]:
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"""Get and convert user input form"""
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# Get raw user input form based on app mode
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if app.mode in {AppMode.ADVANCED_CHAT, AppMode.WORKFLOW}:
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if not app.workflow:
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raise MCPRequestError(mcp_types.INVALID_REQUEST, "App is unavailable")
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raw_user_input_form = app.workflow.user_input_form(to_old_structure=True)
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else:
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if not app.app_model_config:
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raise MCPRequestError(mcp_types.INVALID_REQUEST, "App is unavailable")
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features_dict = app.app_model_config.to_dict()
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raw_user_input_form = features_dict.get("user_input_form", [])
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# Convert to VariableEntity objects
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try:
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return self._convert_user_input_form(raw_user_input_form)
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except ValidationError as e:
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raise MCPRequestError(mcp_types.INVALID_PARAMS, f"Invalid user_input_form: {str(e)}")
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def _convert_user_input_form(self, raw_form: list[dict]) -> list[VariableEntity]:
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"""Convert raw user input form to VariableEntity objects"""
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return [self._create_variable_entity(item) for item in raw_form]
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def _create_variable_entity(self, item: dict) -> VariableEntity:
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"""Create a single VariableEntity from raw form item"""
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variable_type = item.get("type", "") or list(item.keys())[0]
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variable = item[variable_type]
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return VariableEntity(
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type=variable_type,
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variable=variable.get("variable"),
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description=variable.get("description") or "",
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label=variable.get("label"),
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required=variable.get("required", False),
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max_length=variable.get("max_length"),
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options=variable.get("options") or [],
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)
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def _parse_mcp_request(self, args: dict) -> mcp_types.ClientRequest | mcp_types.ClientNotification:
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"""Parse and validate MCP request"""
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try:
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return mcp_types.ClientRequest.model_validate(args)
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except ValidationError:
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try:
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return mcp_types.ClientNotification.model_validate(args)
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except ValidationError as e:
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raise MCPRequestError(mcp_types.INVALID_PARAMS, f"Invalid MCP request: {str(e)}")
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def _retrieve_end_user(self, tenant_id: str, mcp_server_id: str) -> EndUser | None:
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"""Get end user - manages its own database session"""
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with Session(db.engine, expire_on_commit=False) as session, session.begin():
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return (
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session.query(EndUser)
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.where(EndUser.tenant_id == tenant_id)
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.where(EndUser.session_id == mcp_server_id)
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.where(EndUser.type == "mcp")
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.first()
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)
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def _create_end_user(
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self, client_name: str, tenant_id: str, app_id: str, mcp_server_id: str, session: Session
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) -> EndUser:
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"""Create end user in existing session"""
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end_user = EndUser(
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tenant_id=tenant_id,
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app_id=app_id,
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type="mcp",
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name=client_name,
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session_id=mcp_server_id,
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)
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session.add(end_user)
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session.flush() # Use flush instead of commit to keep transaction open
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session.refresh(end_user)
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return end_user
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def _handle_mcp_request(
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self,
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app: App,
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mcp_server: AppMCPServer,
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mcp_request: mcp_types.ClientRequest,
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user_input_form: list[VariableEntity],
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session: Session,
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request_id: Union[int, str],
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) -> mcp_types.JSONRPCResponse | mcp_types.JSONRPCError | None:
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"""Handle MCP request and return response"""
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end_user = self._retrieve_end_user(mcp_server.tenant_id, mcp_server.id)
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if not end_user and isinstance(mcp_request.root, mcp_types.InitializeRequest):
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client_info = mcp_request.root.params.clientInfo
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client_name = f"{client_info.name}@{client_info.version}"
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# Commit the session before creating end user to avoid transaction conflicts
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session.commit()
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with Session(db.engine, expire_on_commit=False) as create_session, create_session.begin():
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end_user = self._create_end_user(client_name, app.tenant_id, app.id, mcp_server.id, create_session)
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return handle_mcp_request(app, mcp_request, user_input_form, mcp_server, end_user, request_id)
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