The system lives in your files, not your prompts
AI Harness Engineering · Essay One · derek wang (derekwang85) Ask a senior engineer where "the system" lives and they'll point at the code, or the org chart. After shipping enough AI-governed projects, I'd point somewhere else: the system lives in the files that fence in what a model is allowed to generate. The longer I watch teams steer language models, the surer I am that the difference between…
The system lives in files, not prompts, according to a senior engineer who witnessed the impact of this realization. The difference between a project that remains consistent and one that deviates is determined by the files that guide the model's output. These files form a pyramid of constraints, with five layers: strategy, architecture, contracts, gates, and implementation.
Each layer builds upon the previous one, narrowing down the possibilities and providing a clear set of rules for the model to follow. The system's output is bounded by the files it reads before generating any content, making the constraints non-negotiable. By shifting from prompts to rules in files, teams can create a more robust and predictable AI system.
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