chore: import upstream snapshot with attribution

examples/stories/lifespan/server_lowlevel.py

@@ -0,0 +1,66 @@
+"""Process-scoped dependency injection via lowlevel `Server(lifespan=...)`."""
+
+from collections.abc import AsyncIterator
+from contextlib import asynccontextmanager
+from dataclasses import dataclass
+from typing import Any
+
+import mcp_types as types
+
+from mcp.server.context import ServerRequestContext
+from mcp.server.lowlevel import Server
+from stories._hosting import run_server_from_args
+
+
+@dataclass
+class AppState:
+    db: dict[str, str]
+
+
+@asynccontextmanager
+async def app_lifespan(server: Server[AppState]) -> AsyncIterator[AppState]:
+    db = {"alpha": "one", "beta": "two"}
+    try:
+        yield AppState(db=db)
+    finally:
+        db.clear()
+
+
+LOOKUP_INPUT_SCHEMA: dict[str, Any] = {
+    "type": "object",
+    "properties": {"key": {"type": "string"}},
+    "required": ["key"],
+}
+
+
+def build_server() -> Server[AppState]:
+    async def list_tools(
+        ctx: ServerRequestContext[AppState], params: types.PaginatedRequestParams | None
+    ) -> types.ListToolsResult:
+        return types.ListToolsResult(
+            tools=[
+                types.Tool(
+                    name="lookup",
+                    description="Look up a key in the process-scoped store.",
+                    input_schema=LOOKUP_INPUT_SCHEMA,
+                )
+            ]
+        )
+
+    async def call_tool(
+        ctx: ServerRequestContext[AppState], params: types.CallToolRequestParams
+    ) -> types.CallToolResult:
+        assert params.name == "lookup" and params.arguments is not None
+        value = ctx.lifespan_context.db[params.arguments["key"]]
+        return types.CallToolResult(content=[types.TextContent(text=value)])
+
+    return Server[AppState](
+        "lifespan-example",
+        lifespan=app_lifespan,
+        on_list_tools=list_tools,
+        on_call_tool=call_tool,
+    )
+
+
+if __name__ == "__main__":
+    run_server_from_args(build_server)