Abstract: If dark matter is a particle with a mass between the electroweak and Planck scale, we could detect it through its decays to high-energy cosmic rays. Testing this hypothesis requires a detailed understanding of the astrophysics of where these decays are occurring and the particle physics that dictates the spectra of produced cosmic rays. In this talk, I will describe recent progress on both fronts. On the astrophysics side, searches within our own Milky Way halo can significantly outperform extragalactic observations, and I will demonstrate how this insight allows for a definitive statement to be made about a longstanding decaying dark-matter anomaly, the 3.5 keV X-ray line. On the particle physics side, I will outline how to perform a field theory calculation at energies approaching the Planck scale, and show how working with the full unbroken Standard Model produces dark-matter spectra that differ by orders of magnitude from previous estimates.