Hi, we don't have reliable documentation for the HTTP API endpoints yet, mostly as they are still subject to change.

However, to briefly provide some context, `/_train_model` returns a stream of line delimited JSON objects for each gradient step as the model trains on the provided trajectories so the client can monitor progress. The final version of this endpoint may provide the option for both streaming & non-streaming responses, and/or potentially return a "training job" that can be polled instead.