Why Your Production LLM Prompt Keeps Failing (And How to Diagnose It in 4 Steps)

You ship a prompt. It works in the playground. Two weeks later, someone files a bug: the model is doing something completely wrong in a specific context. You read the prompt again. Nothing looks broken. So you rewrite it. The bug is gone — but now three other behaviors regressed. You fix those, and the cycle starts again. This is the most common failure mode in production LLM systems: debugging by intuition, fixing by rewrite . The problem isn't that the prompts are bad. The problem is there's n