Function modern_on_request

src/mcp/server/runner.py:499–520

Return an `OnRequest` callback that serves each call via `serve_one` with a fresh per-request `Connection`. Wire this into the server side of a `DirectDispatcher` peer-pair to drive an in-process server on the modern per-request-envelope path (each request carries protocol version, clie

(server: Server[LifespanT], lifespan_state: LifespanT)

def modern_on_request(server: Server[LifespanT], lifespan_state: LifespanT) -> OnRequest:
    """Return an `OnRequest` callback that serves each call via `serve_one` with a fresh per-request `Connection`.

    Wire this into the server side of a `DirectDispatcher` peer-pair to drive an
    in-process server on the modern per-request-envelope path (each request
    carries protocol version, client info, and capabilities in `params._meta`;
    no `initialize` handshake). Like `serve_one`, this raises whatever the
    handler chain raises - the dispatcher owns the exception-to-error mapping.
    """

    async def handle(
        dctx: DispatchContext[TransportContext], method: str, params: Mapping[str, Any] | None
    ) -> dict[str, Any]:
        meta = (params or {}).get("_meta", {})
        connection = Connection.from_envelope(
            meta.get(PROTOCOL_VERSION_META_KEY, LATEST_MODERN_VERSION),
            meta.get(CLIENT_INFO_META_KEY),
            meta.get(CLIENT_CAPABILITIES_META_KEY),
        )
        return await serve_one(server, dctx, method, params, connection=connection, lifespan_state=lifespan_state)

    return handle