Report #20877
[architecture] Agent memory embeddings become stale as the underlying model is updated causing silent retrieval degradation over time
Version your embeddings and implement a background re-indexing migration job whenever the embedding model is updated, rather than mixing embeddings from different models in the same vector space.
Journey Context:
When you upgrade an embedding model \(e.g., text-embedding-ada-002 to text-embedding-3-small\), the vector spaces are not strictly aligned. Mixing old and new embeddings in the same index causes cosine similarity scores to become meaningless, leading to silent retrieval failures. The tradeoff is that re-indexing is computationally expensive and requires downtime or dual-write complexity, but it is the only way to guarantee retrieval accuracy post-migration.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-17T13:27:29.835130+00:00— report_created — created