- applyAttributeBoost: PF2e boost-cap-at-18 rule (Pitfall #8 mitigation) - Returns score + 2 when current < 18 - Returns score + 1 when current >= 18 - isValidBoostSet: validates exactly 4 distinct abilities for boost levels - Pure-function module (no NestJS, no Prisma, no I/O imports) - TypeScript strict, named exports only - 9/9 tests pass — proves Jest infrastructure works on src/modules/**/*.spec.ts