fix nda

migrations/008_covers_from_widen.sql

@@ -0,0 +1,24 @@
+-- BizMatch Phase 2 — module 6a fix: ds_mirror_covers_from may only widen
+--
+-- The value had drifted to a date *later* than the mirror's own oldest row,
+-- so the inbox announced "showing data from <late date>" over a table that in
+-- fact reached months further back. Coverage is now written as
+-- LEAST(existing, reached) (see widenCoverage() in src/nda-refresh.ts); this
+-- corrects the value that is already stored, once, from the only source that
+-- cannot be wrong about it — the mirror itself.
+--
+-- Day-truncated: the mirror holds every request of that day, so midnight is
+-- the honest bound and it is never narrower than the timestamp.
+
+WITH mirror AS (
+  SELECT date_trunc('day', min(created_at) AT TIME ZONE 'UTC') AS from_at FROM ds_request
+)
+INSERT INTO app_meta (key, value)
+SELECT 'ds_mirror_covers_from',
+       to_char(from_at, 'YYYY-MM-DD"T"HH24:MI:SS.MS"Z"')
+  FROM mirror
+ WHERE from_at IS NOT NULL
+ON CONFLICT (key) DO UPDATE
+  SET value = least(app_meta.value, EXCLUDED.value), updated_at = now()
+  -- Only ever widens: a stored value that already reaches further back stands.
+  WHERE app_meta.value IS NULL OR app_meta.value > EXCLUDED.value;