We would like the official MongoDB Kafka Connector to natively support partial updates that append (\$push) records into an array in an upsert scenario—specifically, a built-in WriteModelStrategy to handle use cases where:

We match on a configurable business key (instead of _id) to avoid duplicate documents.
If no document exists, we create one (upsert) with a newly initialized array.
We append (push) each incoming Kafka record to the array on subsequent updates.
We optionally maintain createdTS and modifiedTS timestamps.
This is a common pattern for applications that want to store event logs or historic states in array fields, or otherwise need to accumulate messages over time within a single MongoDB document.