Use models, don't train them
The AI engineer works above the API line. Tokens, sampling, and attention appear only as cost, latency, and quality knobs you actually turn in production.
The open-source AI Engineering handbook for software engineers. Prompts, context engineering, retrieval, agents, evals, and production operations — concise, opinionated, eval-first. No ML PhD required, no sign-up, free under CC BY-SA 4.0.
The defining shift in AI engineering is from "the demo looked good" to "the eval suite passed." This handbook teaches evaluation before RAG and before agents — because you cannot improve what you cannot measure.
The AI engineer works above the API line. Tokens, sampling, and attention appear only as cost, latency, and quality knobs you actually turn in production.
Chapters you finish in eight minutes and apply immediately. Code and diagrams before prose. Every chapter ends with something you can do.
Coming as Part 12: search engines, support agents, coding agents, voice agents — each graded on one shared production rubric, several on public benchmarks.
Twelve parts in a deliberate order: models, APIs, prompting, eval fundamentals, context engineering, retrieval, agents, deep evaluation and observability, security, production, product — with capstones and the interview loop next on the roadmap.
You build your first 50-example eval set in Part 4 — before touching RAG or agents. Nothing in this book ships without a way to know whether it works.
Workflows first, agents as escalation. Tool design, MCP and its security model, voice agents, browser and computer-use agents, and when multi-agent is genuinely worth 15× the tokens.
Prompt caching economics, cost engineering, eval-gated rollouts, incident response, and the product metrics that decide whether your AI feature survives.
A research-backed interview framework: GenAI system design, the new AI-assisted coding rounds, and the eval-design interview almost nobody prepares for.
The book is being written in the open, part by part. Read what's live, watch the rest land.