Moritz Angermann
I don't think Phabricator tries to be or emulate fit in any way; I think this is a misconception. The way I see it, phabricator is just a glorified diff-dump, which is supposed to work with any VCS in principle.
All that arc essentially does is, compute the diff from an offset (e.g. master) to the current HEAD and upload that to a new or existing (--update) differential. It also adds some meta information about the range, such that arc patch supposedly knows into which commit to apply the patch to.
By default arc does not preserve history if memory serves me right but uses the summary field exclusively for the commit message.
Hence you can go wild on your local branches (use what ever development model suites your needs) and get one final squashed commit with an extensive summary.
Sure, but this leads to generally unreviewable patches IMHO. In order to stay sane I generally split up my work into a set of standalone patches with git rebase and then create a Diff of each of these commits. Phabricator supports this by having a notion of dependencies between Diffs, but arcanist has no sensible scheme for taking a branch and conveniently producing a series of Diffs. Cheers, - Ben