verify-checkpoint

Grade ONE signalled increment as a gate — in either of two invocation modes with identical grading: per-increment dispatch (how lsa:delegate drives it) or a standalone self-paced /loop rider. On a checkpoint signal an implementer emits when it pauses having finished one F-requirement, grade that increment does·only — do the scenarios mapped to the target F pass, and does every changed hunk trace to a requirement. Pass both → CLEAR (auto, no human interrupt); fail either → BLOCK naming the failing check, surfaced to the human before the next task. Read-only to the artifacts it grades. NOT lsa:verify (that is the before-delegation grounding check); this is per-increment, after the implementer's changes.