-- 051 — probability contract SHADOW column.
--
-- ADDITIVE AND NULLABLE. Records what the certified serving contract WOULD
-- serve, beside what was actually served. Nothing reads it for serving.
--
-- ORDERING IS LOAD-BEARING: this is applied BEFORE `retentionService` names the
-- column. PostgREST builds a bulk insert from the FIRST row's shape, so a key
-- present on a row whose column does not exist 400s the WHOLE batch — and
-- retention is best-effort, so it fails silently. That is exactly how migration
-- 038 took retention down for three days.
alter table if exists public.model_snapshots
  add column if not exists probability_contract jsonb;

comment on column public.model_snapshots.probability_contract is
  'SHADOW ONLY. {raw_model_probability, served_probability, probability_state, estimator_type, estimator_version, certification_version, model_version, derived:{ev_pct,kelly_pct,value,available}}. Never served; records what the certified contract would have produced.';