Prototype

Throwaway code to answer a design question before you commit. Routes between two approaches: a minimal terminal app when you need to sanity-check state logic or a data model, or multiple radically different UI variations on one route with URL toggles when you're exploring visual design. Everything lives in memory, runs with one command, and gets deleted once you have your answer. The split matters because picking the wrong branch wastes the whole prototype. Good for "does this state machine actually work" or "let me see three different ways this could look" moments. Document what you learned, then throw it away.