Mapper required only that total include {a,b}; rebuild-from-binding then
dropped third entities and could emit a certified wrong answer (e.g. 15
instead of 115). Require exact total part-set {a,b}, refuse any contain
outside reference a, and agree with original-graph classical solve before
emit. Adds multi-entity refuse unit tests.
ADR-0252 §5 geometric SME is NO-GO; this is Track B Increment 1.
Adds role-predicate conversion from MathProblemGraph, S1 canonical skeleton,
blind symbolic mapper (match/refuse + binding), and solve via classical
verify plus multi-register certificate. Research report and holdout measures
included. Serving reader unchanged; no S2–S4 generalization.
