[LLM 8/10] Guardrails: The Real Safety Fence Isn't a Model, It's a Threshold
· 23 min read
The Thai chatbots my team and I deploy for real customers don't only meet polite questions — people ask for recipes for illegal things, people try to trick the bot into insulting others, and there was a day the model volunteered a customer's phone number all by itself. In this chapter we build protection in both directions: a classifier that checks incoming prompts for danger and an outbound PII filter. But the central point of the chapter isn't the model — it's the fact that a guardrail is a threshold decision under asymmetric costs, and the "94% accuracy" figure people love to show off is very nearly meaningless.