The Presigned URL That Expired Before Your User Could Verify the Multimodal Model's Claim
A user opens yesterday's conversation. Next to their support agent's reply sits a broken-image placeholder where their uploaded receipt used to be. The reply confidently quotes "the charge of $47.32 dated March 14 at the merchant Coffee Tribunal." The user has no way to check whether that quote is accurate, because the evidence the model worked from is now a 403 from your object store. They file a hallucination ticket. Your eval suite did not catch it because the model was, at the time of the call, exactly right.
This is a story about retention mismatch, not about model quality. Your transcript outlived its grounding. The grounding was a presigned URL with a fifteen-minute clock, and the claim about the grounding is text that will sit in your database for years. When the asset clock and the claim clock run at different speeds, every correctly-grounded multimodal answer eventually looks like fabrication to whoever revisits it.
