Direction: shared types only (not called directly) · Capability: none (pure data / dispatch)
Mirrors CommandRegistry + CommandInvocation + the closed Effect
enum (lattice-grammar). Guest→host invoke; host→guest apply. The
effect WIT variant mirrors the ~105-variant enum whole (§4.4) so the
boundary stays typed. Populated in PH7.3 (Effect round-trip) / PH7.7.
(none — a shared type interface)