"""Send a vendor-prefixed request via the `client.session` escape hatch.""" from typing import Literal import mcp_types as types from mcp.client import Client from stories._harness import Target, run_client class SearchParams(types.RequestParams): query: str limit: int = 10 class SearchRequest(types.Request[SearchParams, Literal["acme/search"]]): method: Literal["acme/search"] = "acme/search" params: SearchParams class SearchResult(types.Result): items: list[str] async def main(target: Target, *, mode: str = "auto") -> None: async with Client(target, mode=mode) as client: # `Client` only exposes spec-defined verbs, so vendor methods have to drop one # layer to `client.session` today — there is no `Client`-level API for them # yet, and whether `.session` stays public is undecided. `send_request` # accepts any `Request` subclass. request = SearchRequest(params=SearchParams(query="mcp", limit=3)) result = await client.session.send_request(request, SearchResult) assert result.items == ["mcp-0", "mcp-1", "mcp-2"], result if __name__ == "__main__": run_client(main)