Why Your Next.js SaaS Needs a Production AI Agent Guardrail Architecture, Not Just a Prompt

I've spent the last year building production AI pipelines for SaaS platforms. The prompts were solid. The output quality was high. But every time the LLM ran without architectural constraints, something went wrong. Cost exploded. The model fabricated data. An agent took an action nobody authorised. The real problem with AI agents isn't that they hallucinate. It's that they act on their hallucinations before you can stop them. And most Next.js SaaS teams are still treating prompt engineering as...