Tracer Bullets Build features as vertical slices through all layers, verifying each slice before starting the next. From The Pragmatic Programmer: get feedback as quickly as possible. Don't build horizontal layers in isolation (all endpoints, then all UI, then all tests). Build one thin vertical path, verify it works, then expand. Skip for single-layer changes, one-file bug fixes, or work already decomposed into ordered vertical slices by a task tracker. Quick Reference | Principle | Practice | | -------------------------- | --------------------------------------------------------------------…