Prompt is Not Runtime: Why I Rejected LLM State-Machines for Deterministic FinTech

Prompts are Heuristics, Not Code

There is an excellent article trending on Hacker News right now titled "Prompt Is Not Runtime." It targets a major architectural delusion of the current AI-hype cycle: the idea that we can use natural language prompts as a reliable execution runtime for business logic.

When you are building software that handles user data, a "probabilistic" output is annoying. But when you are building a financial engine designed to model the Snowball Effect of life savings, a probabilistic output is an absolute liability.

When I built

Are we treating prompts as runtimes because we've forgotten how to write robust state-machines? Let’s fight it out in the comments.