-- Migration 019: how a merged transcript came about (ADR-034).
--
-- When two engines transcribed the same audio and a local model chose between their
-- disagreements, this records the status, the exact counts, and a bounded list of the
-- contested spots (changed or unsure, each with a position and both readings) so the
-- page can say what was done and the user can check the uncertain spots against the
-- audio. NULL means a single engine: no second opinion, and the page must not claim one.
--
-- It lives on the already-FORCE'd, RLS-scoped uploaded_transcripts, so the exact-set
-- isolation test is unaffected. The contested spots hold fragments of the private
-- transcript, which is why they are here and nowhere else.
ALTER TABLE uploaded_transcripts ADD COLUMN reconciliation JSONB;