Hypothesis-Driven Development (HDD) framework for structuring modernization proposals as testable hypotheses with Lean Startup cycles (Build-Measure-Learn). Transforms features into hypotheses with metrics, experiments, and kill/pivot/persevere thresholds. Use when formulating scenarios as hypotheses, designing validation experiments, applying Lean Startup to discovery, or when "HDD", "hypothesis", "hipótesis", "lean startup", "build-measure-learn", "experiment", "kill/pivot/persevere", or "validación de hipótesis" is mentioned.