Adding a Modality Is a Privacy-Classification Event, Not a Feature Flag
A product manager pings the AI team on a Tuesday: "Customers want to paste screenshots into the support agent. Should be a small lift, right? The model already takes images." The eng lead checks the SDK, confirms the vision endpoint accepts JPEGs and PNGs, ships the change behind a feature flag, and rolls it to ten percent. Two weeks later, the legal team forwards a regulator letter asking why a user's bank statement, an image of their driver's license, and a screenshot containing another customer's order ID all appeared in the agent's training-eligible logs. Nobody on the AI team flagged the modality change, because nobody thought a modality change was a change. The privacy review that approved the text agent never re-ran for the image variant — and the image variant turned out to live under entirely different consent, retention, and residency rules.
This is not a story about a careless engineer. It is a story about a category error built into how most teams ship AI features. Text input is a known data class with a stable threat model: the user types, the user sees what they typed, the engineering team has years of habit around what to log and what to drop. Images are a different data class with a different threat model — they smuggle in metadata the user cannot see, capture surrounding content the user did not intend to share, and create storage and processing footprints with their own residency and contract terms. Treating "now with vision" as a UX iteration, when it is actually a privacy-classification event, is how teams discover at the regulator's request that their PII inventory understated their actual exposure by an order of magnitude.
