The newest event id on the context among the events its change feed would serve you, or null. A hint that can miss a change, not a freshness proof. It is ordered by occurred_at, when the acting transaction began, so a long transaction that begins before a short one and commits after it never moves the cursor past the short one's event. To see every change, read the change feed (GET /api/events/{kb_context_id}/changes), which is commit-ordered and does not have this race.