Legal requires that a deleted customer document be unre...

This is a constraint-based design problem. A 24-hour deletion deadline is a non-negotiable legal requirement, whereas a three-point eval lift is a performance target. Since fine-tuning does not support bounded deletion, it cannot be used for sensitive customer data. The correct approach is to use a SILO split: fine-tune the model only on low-risk, retained data, and store the sensitive, deletable customer text in a retrieval datastore. This satisfies the legal constraint while allowing the team to re-measure the performance impact of the remaining data.