r1-07 now reads setup-correct and answers 6 — 'Nia has 9 more beads than Omar. Nia has 15. -> Omar = 6'. The reader binds the unknown base's unit FROM the relation when its subject is a known fact and its referent is the otherwise-ungrounded query target, so the equation is admissible; the answer oracle reverse-solves it (PR-7a). Bounded: single base == query target (no chains), known subject value, base not otherwise grounded, <=1 inverse (multiple_inverse_bases else), never over times/divide.
R1 setup 6/0/4 -> 7/0/3; R1 answers -> 7 correct / 0 wrong; 15-case 15/0/0; setup_wrong stays 0. Off-serving. Refreshes the R1 ledger to 7/0/3 (R1 closed; the 3 remaining refusals are wrong=0 boundaries).