the RI seam is a derived projection, not stored mint events

Agent-decided, specified and not implemented. roots() gains an activation term computed from reasons() and prestate(), both of which already exist, with ids from mint_ids() which already keys by position. No new event kind. Because roots stays a pure function of the history, D1 then holds by construction in the semantic state and relocates to the boundary where a record is materialized or certified — which is the right place for a conformance condition, and is where the verifier's recomputation catches an omission that no structural check can see. Implementing it edits a previous round's artifact and is reserved to the author.