> Why use a limited version?

Because in most of those API, even many implementations of the Responses API, you lose a lot of control of where your data is going. e.g. an Agent or the Responses API may automatically invoke a tool call that leaks your data to an external service on the internet, without having an option to intervene.

If you want to have control over your data, you have to have control over your harness.

This bothers me so much with the existing offerings. I start with the chat interface then as soon as I want to get technical/run scripts/automation, I have to copy the context into a fresh code session. So cumbersome.