Retrieval Ownership Split

Retrieval Ownership Split is the rule that whoever holds the embedding index controls the client's switching cost, not whoever wrote the application code. A RAG feature has two layers: the query and prompt logic an agency writes, and the index of embeddings plus metadata that makes answers accurate. The first layer is portable in days. The second accumulates months of client documents, tuning, and filters, and it is where retention actually lives. Agencies that hand index custody to a managed platform accept vendor pricing power; Forrester's November 2026 research found AI vendors simultaneously setting usage limits, controlling feature access, and arbitrating disputes over their own tools, which turns a routine price change into a delivery risk. Self-hosting an open-source engine such as Qdrant or Weaviate keeps custody but adds on-call load. The practical move is to name the index owner in every statement of work and price the migration path before the first client retainer renews.