chore: import upstream snapshot with attribution

examples/stories/parallel_calls/server_lowlevel.py

@@ -0,0 +1,48 @@
+"""Rendezvous tool on the lowlevel `Server`, proving concurrent dispatch without `MCPServer`."""
+
+from collections import defaultdict
+from typing import Any
+
+import anyio
+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
+
+MEET_INPUT_SCHEMA: dict[str, Any] = {
+    "type": "object",
+    "properties": {
+        "tag": {"type": "string"},
+        "party": {"type": "array", "items": {"type": "string"}},
+    },
+    "required": ["tag", "party"],
+}
+
+
+def build_server() -> Server[Any]:
+    arrivals: dict[str, anyio.Event] = defaultdict(anyio.Event)
+
+    async def list_tools(
+        ctx: ServerRequestContext[Any], params: types.PaginatedRequestParams | None
+    ) -> types.ListToolsResult:
+        return types.ListToolsResult(
+            tools=[types.Tool(name="meet", description="Rendezvous with peers.", input_schema=MEET_INPUT_SCHEMA)]
+        )
+
+    async def call_tool(ctx: ServerRequestContext[Any], params: types.CallToolRequestParams) -> types.CallToolResult:
+        assert params.name == "meet"
+        assert params.arguments is not None
+        tag = params.arguments["tag"]
+        assert isinstance(tag, str)
+        arrivals[tag].set()
+        for peer in params.arguments["party"]:
+            await arrivals[peer].wait()
+        await ctx.session.report_progress(1.0, total=1.0, message=tag)
+        return types.CallToolResult(content=[types.TextContent(text=tag)])
+
+    return Server("parallel-calls-example", on_list_tools=list_tools, on_call_tool=call_tool)
+
+
+if __name__ == "__main__":
+    run_server_from_args(build_server)