Scoping + holdout validation of the VERIFIED canonical-comparison producer (the
ADR-0206 §5 math-serving widening's gate). Records the empirical verdict so it is
not re-chased: on holdout_dev the fold-derivation reader is 2 correct / 87 wrong on
candidate-graph-refused cases, and a pure-chain certifier would admit 37 wrong (a
wrong=0 breach) — the train_sample 3/7 was overfit. math_verifier.verify is
solver-replay soundness, not correctness; the R1 graph reader is nested (0 flips).
Math serving is comprehension-bound; the math seam correctly stays inert; the real
lever is the general COMPREHEND organ, not a narrow GSM8K certifier. No code change.
