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Cover of the Context Engineering Field Guide: 100,000 noisy tokens of raw input become curated context through retrieve, rerank, prune, checkpoint and cache.

Field Guide 01 · Free PDF

Context Engineering

What should your AI actually see?

More context isn't always better. Learn how to select, structure, and evaluate the information your LLMs and agents receive.

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By Amit Kumar10-page PDF201 KB2026 edition

What you will work through

A compact field guide to building the context your RAG systems and AI agents receive at every model call: what to retrieve, what to prune, what to carry forward as structured state, and how to prove a smaller context is still sufficient.

Format
PDF, 10 pages, 201 KB
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For
Engineers building RAG systems, AI agents and production LLM applications.
Updated
  1. 01p. 2

    Long-context limits and Lost in the Middle

    Why a context window measures capacity, not usefulness. Separates capacity, relevance and sufficiency, and treats the U-shaped position effect as a research observation rather than a universal curve.

  2. 02pp. 3–4

    Context selection and prioritization

    A six-step pipeline run at every meaningful call: understand, fetch, select, pack, reason, checkpoint. Covers hybrid lexical and dense retrieval, and reranking for coverage over similarity.

  3. 03pp. 4–5

    Dynamic pruning and compression

    Remove duplicate logs, superseded tool output and stale turns while preserving negative evidence and constraints. Compaction that pins critical qualifiers instead of silently erasing them.

  4. 04pp. 5, 7

    Structured agent state

    Progressive disclosure through pointers, and a reusable context packet that keeps verified facts, labeled hypotheses and missing evidence apart.

  5. 05pp. 5, 8

    Context budgets and caching

    An explicit token budget for the next call, a cost model that includes cached reads and writes, and why prefix caching speeds computation without making weak evidence reliable.

  6. 06pp. 6, 9–10

    Worked example and production checklist

    An illustrative incident-investigation agent reduced from 100,000 raw tokens to an 11,800-token packet, a three-way evaluation ablation, and a one-page implementation checklist with sources.

Two pages from the guide

Guide page 3: a six-step context loop of understand, fetch, select, pack, reason and checkpoint, with notes on task-aware retrieval and separating facts from hypotheses.
Page 3 · Build a context pipeline
Guide page 7: a schematic JSON context packet with task, constraints, verified facts, unconfirmed hypotheses, evidence IDs, missing information and the next action.
Page 7 · A reusable context packet

Context Engineering Field Guide

10-page PDF · 201 KB · Free. No account or email required.

Download free PDF

Go deeper on ArchCrux

Reading paths:Production AI agents →RAG in production →