The breakdown of the four properties (masking, consistency, persistence, isolation) is a useful way to think about this. The real friction shows up when you layer real authentication on top of these. Cookies and session tokens tied to a browser profile work until the profile changes or the agent restarts.

The harder problem is when agents need to sign transactions, hold credentials, or prove their identity to a service independently of the browser they are running in. That is a different kind of persistence. Cryptographic identity that survives process restarts, browser swaps, and even machine migrations.

Browser fingerprinting keeps the browser looking like itself. But the agent also needs credentials that travel with it, not with the browser profile it happens to be using. CAI addresses this by giving agents their own programmable wallets and verifiable credentials, so the agent's identity is attached to the agent itself.