T-CI-01

Registry coherence is mechanically checked by ci_check_registry_code_locus_exists.sh (unique ids, directed cross_ref targets resolve, code_locus paths exist); this supports but does NOT fully enforce the rule — full proof that every true invariant has a substantive enforcement point remains open. (Reconciled after retiring a foreign coverage gate; see docs/planning/registry-cross-ref-bidirectional-repair.md.)