Context engineering
Designing everything the model can see besides your prompt: files, retrieved documents, memory, tool outputs and history.
As models got better at following instructions, the bottleneck moved from wording to context. Context engineering is the discipline of assembling the right material, in the right structure, at the right moment.
Practical rules: curate rather than dump, connect changing sources instead of pasting stale copies, decide deliberately what persists across sessions, and restate the goal in long threads before context rot sets in.