Prompt Debt Is the New Technical Debt — And Nobody's Tracking It

Technical debt has a well-understood cousin that nobody talks about yet: prompt debt. Every ad-hoc prompt an engineer writes - the one-off system message, the quick-and-dirty few-shot template, the "I'll clean this up later" instruction set - carries the same compounding cost properties as a hardcoded value or a skipped test. Except prompt debt is invisible. There's no linter. No coverage metric. No PR review process. And it's about to get worse: Gartner says 40% of enterprise apps will embed AI agents by the end of 2026. Every one of those agents runs on prompts.