Context engineering: the job prompt engineering grew into
A model knows two things when it answers: what it learned in training, and what is in its context window for this request. You cannot change the first at request time. Context engineering is the discipline of controlling the second: choosing the sources, selecting from them, fitting the result into a budget, and putting it in an order and format the model uses well. The term caught on as teams moved from single prompts to agents and retrieval systems, where most of the context is no longer written by a person. It is assembled by code, on every request, from data that changes. Good instructions still matter. They are simply one input among six or seven, and usually the most stable one. Each source has its own owner, freshness and permission rules. Context engineering is where they meet. A large context window is a ceiling, not a target (see a context window is not memory). Treat it as a…
