Currently uses datetimestamp with time data discarded, such as 20170501 0:00:00 UT. but all calculations treat this as a date, so there is a lot of conversion code, which may be inconsistent, and there are lots of opportunities for fencepost errors, such as where midnight is counted. There are also a few "day + 1" hacks in the code. All of this should be eliminated in favor of treating all timestamps from Phabricator as dates only. This will change a core database table column and be a big refactor.
The most visible consequence of this is that the Status report start and end cutoffs are very confusing, which leads to difficulty validating the report because a sample task may be done in Phabricator on a certain day but not be reflected as expected in the Status report.