渾儀 (Hunyi) — the semantic observation dimension of Tianheng: declare in Rust how a module's public surface must behave — what types its API must not expose (including via named public re-exports, and — opt-in — a trait impl's impl-site-authored positions), where a trait may be implemented, that a module declares no bare pub, which markers a type must not acquire, and that its seam exposes no dyn / impl Trait (shape or a named trait) or async fn — observed via the AST (syn), reacted in CI. The semantic complement of the static import boundary; the syn dependency is quarantined here, never in the core.