verification-authoring

Author Verification Definitions for Duhem — the structured YAML artifact containing a feature's acceptance criteria and the checks that mechanically verify them. This is the central authoring discipline that any Duhem-shaped customer (including Duhem itself, when it dogfoods on Onsager) eventually internalizes.

The canonical product spec is in docs/duhem-spec.md, especially:

• §7 — Core Concepts (verification, criterion, check, assertion, step, verdict, evidence, artifact, run)
• §8 — Holistic Verification Principle
• §10 — Verification Definition (file org, structure, action types, assertions, runtime expressions, extensibility)
• §11.2 — Trust Boundary (what AI may and may not do at run time)

This skill is the authoring counterpart to those sections.