In both Differential and Diffusion? Just Differential? That's something that upstream Phab should decide.
greg mentioned this in T182: Support automatic commit generation in Phabricator.Nov 4 2015, 7:11 PM2015-11-04 19:11:08 (UTC+0)
greg added a parent task: T117058: Initial documentation of example Differential workflows (with Gerrit equivalents).