Search replication currently measures per-index lag against the cluster-level majority committed optime. This overstates user-visible lag for idle collections, because unrelated writes on other collections advance the cluster optime even when a given collection has no updates. We would like server to expose the most recent majority-committed optime per collection/namespace, so mongot can compare an index’s replicated optime against the latest relevant write for that index’s source collection.

This would let Atlas Search report a more accurate freshness metric, make smarter multitenant replication scheduling decisions.