Jan: Model switching while the server is running

[eckartal]

Overview

Jan users start their own Jan servers with one model and they can't change the model while the server is running. We should support changing models remotely.

Goals

• Allowing change of the active model from any client device (phone, laptop, etc.)
• Provide multiple model-switching methods to suit different use cases (API, UI, automatic?)
• Ensure minimal downtime during the model-switching process