When Content Betrays Code: How Data Duplication Created costto.build's Hidden Bug

This article exposes a fundamental software problem: when identical data is stored in multiple places, they inevitably diverge without a forcing function to keep them synchronized. The author's solution—making the calculator function the sole source of truth and deriving all other values from it at build time—demonstrates a practical application of DRY that extends beyond code to data and content generation. This pattern is essential for anyone developing content-heavy platforms, configuration-driven systems, or any product where consistency between different representations of the same information is critical to user trust.