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What is context engineering and how does it differ from prompt engineering?

Q: What is context engineering and how does it differ from prompt engineering?

**TL;DR.** Prompt engineering crafts the **instruction**; context engineering designs **everything the model sees** — rules, retrieved docs, memory, tool results, examples — under a **token budget**. In RAG and agent systems, context assembly moves quality more than wording. retrieved docs memory / profile tool results history +

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Understand the problem

The discipline of deciding what the model sees: retrieval, memory, tools and budget allocation.

context-engineeringpromptingragmemory

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Read the code

A context assembler with explicit budgets

function assembleContext(q: Query, budget: number) {
  const parts = [
    { text: SYSTEM_RULES,                     priority: 0 },   // stable prefix
    { text: relevantMemories(q, 3),           priority: 1 },
    { text: rerank(retrieve(q, 40)).slice(0, 6), priority: 2 },
    { text: summarizeOldTurns(q.history),     priority: 3 },
    { text: lastTurnsVerbatim(q.history, 4),  priority: 1 },
  ];
  return admitByPriorityUntil(parts, budget); // evict low-priority overflow
}

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