The Illusion of Data Custody in Legal AI — and the Architecture I Built to Replace It

**There is a moment every legal AI founder eventually has to confront. You have built a capable system. The retrieval is good. The citations hold up. The interface is clean. A lawyer uploads a sensitive client document and asks a question. The system answers correctly. Then they ask: what happens to this document when I delete it? And that is where most legal AI products fail quietly. Not because the founders were careless. Because they treated data custody as a policy question rather than an architecture question. They added a delete button, wrote a privacy policy, and moved on. This article is about what I built instead — and why the distinction between a deletion confirmation and a cryptographic Destruction Receipt matters enormously in legal contexts.** SECTION 1: What actually happens when you click delete Most AI SaaS platforms handle deletion at the application layer. The record is flagged as deleted. The UI stops showing it. The underlying data — the vector embeddings, the chun