📜 WAYPOINT LESSON
Checkpoint: exam #2 FRQ
⭐⭐⭐ advanced⏳ 25 min read📍 Lesson 248 of 256
The recipe scaler: proportion, guard-on-failure, and state floor.
The FRQ emphasizes the guarded transition: serve must decide
success BEFORE mutating — a return-first bug here flips the state
on failure. Bank scaleTo immediately (one line), then remaining/
addServings, then serve's guard-last discipline.