Use when the user asks to "test a hypothesis", "validate assumptions through delivery", "run experiment-driven project", "design build-measure-learn cycles", "validate project assumptions", or mentions hypothesis-driven delivery, HDD, validated learning, experiment design, build-measure-learn. Triggers on: converts assumptions into testable hypotheses, designs minimum viable experiments, facilitates pivot-or-persevere decisions, documents validated learning, ranks hypotheses by risk and impact.