from collections.abc import AsyncIterator

from contextlib import asynccontextmanager

from dataclasses import dataclass

from mcp.server.mcpserver import Context, MCPServer

class Database: # Replace with your actual DB type

@classmethod

async def connect(cls): # pragma: no cover

return cls()

async def disconnect(self): # pragma: no cover

pass

def query(self): # pragma: no cover

return "Hello, World!"

# Create a named server

mcp = MCPServer("My App")

@dataclass

class AppContext:

db: Database

@asynccontextmanager

async def app_lifespan(server: MCPServer) -> AsyncIterator[AppContext]: # pragma: no cover

"""Manage application lifecycle with type-safe context"""

# Initialize on startup

db = await Database.connect()

try:

yield AppContext(db=db)

finally:

# Cleanup on shutdown

await db.disconnect()

# Pass lifespan to server

mcp = MCPServer("My App", lifespan=app_lifespan)

# Access type-safe lifespan context in tools

@mcp.tool()

def query_db(ctx: Context[AppContext]) -> str: # pragma: no cover

"""Tool that uses initialized resources"""

db = ctx.request_context.lifespan_context.db

return db.query()