The precision of current lattice QCD calculations of the direct CP-violating parameter $\varepsilon'$ now require the inclusion of $\Delta I = 1/2$ rule-enhanced, isospin-breaking effects. Here we give an update on the program to include electromagnetism and quark mass differences in a first-principles calculation of $\varepsilon'$. We combine finite-volume hadronic matrix elements with an infinite-volume photon propagator. In order to avoid large finite-volume effects due to low-energy $\pi\pi\gamma$ states, we omit low-energy photons but show this introduces a negligible error.