- tickets.closure_events: append-only observed closures (PK ticket_id, closed_at;
observed_at = first sighting; survives row churn).
- tickets.inc_daily_snapshot: one row per EAT day — open backlog (+ SLA split, by
cluster/status) and created/closed flow; upserted each run.
- tickets.capture_history(): appends new closures + upserts today's snapshot.
- import_tickets calls it after each --apply run (ingest or skip); add
--capture-history CLI flag for standalone runs.
Verified: backfilled 21,282 closures; today's snapshot recorded (open_total 30).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>