The [websocket::stream::async_read_some](https://www.boost.org/doc/libs/develop/libs/beast/doc/html/beast/ref/boost__beast__websocket__stream/async_read_some.html) page should mention how [websocket::stream::is_message_done](https://www.boost.org/doc/libs/1_87_0/libs/beast/doc/html/beast/ref/boost__beast__websocket__stream/is_message_done.html) can be used to determine if the last read operation completed the current message.