ADR 06: :ret is required and final

Date: 2026-06-16

Context

The signature vector needs a rule for where the return marker sits and whether it is optional.

Decision

Require :ret in the proof of concept and allow nothing after it.

Consequences

Native boundaries always carry an explicit return contract, and a final marker keeps parsing simple and signatures readable.

Alternatives

An optional or inferred return type was considered; inference across a native boundary is unreliable, and optionality removes the explicit contract the boundary needs.