The Wide Field Infrared Survey Telescope (WFIRST) is an upcoming NASA observatory that will investigate dark energy, exoplanets, and infrared astrophysics. The first of these areas, dark energy, continues to be one of the most enigmatic cosmological discoveries. With the goal of shedding light on the nature of the origin of cosmic acceleration, the WFIRST High Latitude Survey (HLS) will deliver a dataset with the statistical power to make extremely precise measurements of cosmic expansion and structure growth. I will give an overview of our approach to the design and implementation of the cosmology program of the HLS, specifically highlighting the tools we are building to characterize sources of systematic error in the near-infrared detectors and propagate their impact to cosmology constraints.