LinkClient

async def open(self) -> None:
    """Connect, perform ``hello`` handshake, await ``welcome``.

    ``LocalLink`` makes this a no-op — connection is implicit when
    the link is created.
    """
    ...

async def send_frame(self, frame: Frame) -> None:
    """Push a frame towards the hub."""
    ...

def frames(self) -> AsyncIterator[Frame]:
    """Async iterator of inbound frames from the hub.

    Iteration ends when ``close()`` is called.
    """
    ...

async def close(self) -> None:
    """Drain queues, signal close to the hub-side handler."""
    ...