Alternative, and more robust approach is to give the agent surrogate credentials and replace them on the way out in a proxy. If proxy runs in an environment to which agent has no access to, the real secrets are not available to it directly; it can only make requests to scoped hosts with those.

I’ve built this in Airut and so far seems to handle all the common cases (GitHub, Anthropic / Google API keys, and even AWS, which requires slightly more work due to the request signing approach). Described in more detail here: https://github.com/airutorg/airut/blob/main/doc/network-sand...