Really cool idea! It’s true that the web isn’t yet agent-ready, and this could be an easy way to start that process. I think the main challenge that comes to mind is auth on the tool-calling side, unless I’m not understanding correctly
Auth is level 2 of this design. It is huge piece of the puzzle. My vision for this is that the kodec.txt protocol would evolve to include an optional authentication block, likely declaring a standard like OAuth 2.0.
Doing so, a trusted agent (that the user has already connected to their account, similar to a "Login with Google" flow) would see that the action requires authorization. The agent would then be responsible for managing the OAuth token on behalf of the user to securely make the authenticated API call.
For this POC, all the actions are public and unauthenticated to keep it simple, but your question is exactly where the protocol needs to go next to handle private, user-specific actions. It's a massive and exciting challenge. Thanks for bringing it up!
What you could do is maybe create and host your own token storage, include a tool to retrieve it from within each kodec.txt file based on some reference id cookie in the browser, and see how far you get there