Function serve_one

src/mcp/server/runner.py:473–496

Handle a single request ``(method, params)`` and return its result dict. The single-exchange driver: builds the kernel, runs `on_request` once under `dctx`, and tears down `connection.exit_stack` (shielded) on the way out. The entry constructs the (born-ready) `Connection` and the `dctx

(
    server: Server[LifespanT],
    dctx: DispatchContext[TransportContext],
    method: str,
    params: Mapping[str, Any] | None,
    *,
    connection: Connection,
    lifespan_state: LifespanT,
)

async def serve_one(
    server: Server[LifespanT],
    dctx: DispatchContext[TransportContext],
    method: str,
    params: Mapping[str, Any] | None,
    *,
    connection: Connection,
    lifespan_state: LifespanT,
) -> dict[str, Any]:
    """Handle a single request ``(method, params)`` and return its result dict.

    The single-exchange driver: builds the kernel, runs `on_request` once under
    `dctx`, and tears down `connection.exit_stack` (shielded) on the way out.
    The entry constructs the (born-ready) `Connection` and the `dctx`; this
    only consumes them.

    Raises whatever the handler chain raises (`MCPError` / `ValidationError` /
    unmapped); callers own the exception-to-wire mapping.
    """
    runner = ServerRunner(server, connection, lifespan_state)
    try:
        return await runner.on_request(dctx, method, params)
    finally:
        await aclose_shielded(connection)


def modern_on_request(server: Server[LifespanT], lifespan_state: LifespanT) -> OnRequest: