chore: import upstream snapshot with attribution

examples/snippets/servers/lifespan_example.py

@@ -0,0 +1,56 @@
+"""Example showing lifespan support for startup/shutdown with strong typing."""
+
+from collections.abc import AsyncIterator
+from contextlib import asynccontextmanager
+from dataclasses import dataclass
+
+from mcp.server.mcpserver import Context, MCPServer
+
+
+# Mock database class for example
+class Database:
+    """Mock database class for example."""
+
+    @classmethod
+    async def connect(cls) -> "Database":
+        """Connect to database."""
+        return cls()
+
+    async def disconnect(self) -> None:
+        """Disconnect from database."""
+        pass
+
+    def query(self) -> str:
+        """Execute a query."""
+        return "Query result"
+
+
+@dataclass
+class AppContext:
+    """Application context with typed dependencies."""
+
+    db: Database
+
+
+@asynccontextmanager
+async def app_lifespan(server: MCPServer) -> AsyncIterator[AppContext]:
+    """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:
+    """Tool that uses initialized resources."""
+    db = ctx.request_context.lifespan_context.db
+    return db.query()