Context engineering is the discipline of deliberately deciding what a language model sees, in what order, in what shape, and in what volume, before it ever generates a token. It replaced prompt engineering as the primary lever for reliability once production systems moved past single-turn chat into agents that call tools, read documents, and run for dozens of steps — because at that point, the wording of an instruction stopped being the thing that broke, and the composition of everything around that instruction started being the thing that broke. 🧭 This matters because most production LLM failures are context failures wearing a model-quality costume. A coding agent that "forgets" a constraint from ten turns ago, a research agent that contradicts itself over a long session, a support bot that answers confidently from the wrong document — in each case the underlying model is usually fine. It never received the right slice of information, in the right position, at the rig...