message_graph dichotomy contract — draft→approved→building→verifying→
closed in ONE process. Evidence: parity 1f7a2664, Phase B 7194f69a
(pushed gitea/master); battery 12 tests replay 68 frozen-oracle cases
VERBATIM; live parity 68/68 byte-identical; clippy 0; Python suite 9+9
under both RUNE_MG_CORE pins. Contract-walk script included (one-
process clobber-hazard law).
