Quoted from linked article:
"PersonaPlex accepts a text system prompt that steers conversational behavior. Without focused instructions, the model rambles — it’s trained on open-ended conversation and will happily discuss cooking when asked about shipping.
Several presets are available via CLI (--list-prompts) or API, including a general assistant (default), customer service agent, and teacher. Custom prompts can also be pre-tokenized and passed directly.
The difference is dramatic. Same input — “Can you guarantee that the replacement part will be shipped tomorrow?”:
No prompt: “So, what type of cooking do you like — outdoor grilling? I can’t say for sure, but if you’re ordering today…”
With prompt: “I can’t promise a specific time, but we’ll do our best to get it out tomorrow. It’s one of the top priorities, so yes, we’ll try to get it done as soon as possible and ship it first thing in the morning.”"