Rigorous problem-solving method for backward-chaining from a goal to a task breakdown, with disciplined assumption-handling and an optimist default. Use whenever solving a problem, designing a system or plan, evaluating a decision, or making a recommendation - not just on explicit request. Especially trigger when the user says "think this through," "challenge assumptions," or is working through a multi-step or ambiguous problem where jumping straight to a solution risks solving the wrong thing.
