Interface domain: Policy

Status: EXPERIMENTAL capability domain — NOT a normative specification (docs/interface-model.md §2). Adding required semantics here is a proposal, not an edit.

Purpose. Normative rules: what is permitted inside what the environment supports — the SHOULD layer above the CAN rail.

Wire format. None specified in v0.1.

Open questions. Boundary with decision: whether policy evaluation and feasibility evaluation need distinct wire objects or one decision object with two reason families.

Formalization trigger. A policy engine and a feasibility engine composing in one deployment.