Lifecycle rules are the problem

Class FRQs are won in the lifecycle rules — the sentences that say when state may change:

• "coins reset to zero when the machine is emptied" → a getter with a side effect (emptyCoins).
• "a song becomes liked on its FIFTH play" → == 5, not >= 5 (the sixth play must do nothing).
• "a player at 0 HP cannot be damaged or healed" → BOTH mutators guard on the same condition.
• "restock happens even when empty" → a transition with no guard.

Underline every rule sentence; each one is one if (or one deliberate absence of an if). Then implement the class in spec order — constructor first, transitions next, accessors last — and re-read the rules against your ifs. A missing guard is invisible in the happy path; that is why the graders wrote hidden tests for it.