ACI-009: Context Engineering vs Prompt Engineering

Thesis

Prompt engineering is what you say in one interaction; context engineering is everything the agent reads before you say it, from the guidance file and memory to the shape of the repository and the state of the session. When an agent behaves stupidly, look first for a gap in that context, not a weak model. A context artefact that describes something else drifts from it unless something holds the two together.

Story

The term "prompt engineering" dominated talk about AI from 2023 onward. Courses, certifications and job titles grew up around the skill of writing effective prompts. For single-turn interactions this makes sense: the prompt is the only lever.