I'd likely say that the records are AEAD ciphertext and let the AEAD decide on what that means. But as for allowing handshake messages, alert messages etc to m

I'd likely say that the records are AEAD ciphertext and let the AEAD decide on what that means. But as for allowing handshake messages, alert messages etc to mix with application data, no. (See the QUIC design as an example: https://docs.google.com/document/d/1g5nIXAIkN_Y-7XJW5K45IblHd_L2f5LTaDUDwvZ5L6g/edit https://docs.google.com/document/d/1g5nIXAIkN_Y-7XJW5K45IblH...)