The plan for online authenticated encryption in Miscreant is to support Rogaway's CHAIN and STREAM constructions:

STREAM: https://github.com/miscreant/miscreant/issues/32

CHAIN: https://github.com/miscreant/miscreant/issues/33

These schemes achieve a security definition called OAE2 (STREAM specifically achieves nOAE, which Rogaway proves equivalent to OAE2) and are robust against reordering and truncation attacks. For more information, please see the paper:

http://web.cs.ucdavis.edu/~rogaway/papers/oae.pdf