HAF was designed to automatically handle micro-forks. It actually has two modes:1) in the default mode, it tracks all changes up in your app's tables up to the last irreversible block, so it can revert those changes in case of a fork and 2) irreversible mode, where it the blockchain data is only made available to your app after the block becomes irreversible. Originally I planned for a lot of apps to use the default mode, but with OBI, using the second mode works pretty well too (and it is slightly faster).