Nothing is published here yet. When it is, expect writing on the same terms as the rest of fvequals: named sources, stated assumptions, and no rounding a real number up to a nicer-sounding one.
Planned topics include how the safe withdrawal rate calculations work, what changes when CPI category weights shift, and the tradeoffs behind the app's approach to tax modeling. None of it is written yet — check back later, or read the Methodology page for the same rigor in reference form today.