It is the practical counterpart to the previous one: where that book explains what breaks, this one hands you the code. I used it the way cookbooks are used, opening what I needed.
What I did with it
The reranking recipes gave me the argument for always including that step rather than offering it as an option: retrieving twenty passages and keeping the best five costs less compute than a larger model and improves the answer more.
The evaluation chapter left me a practice that is now part of what I deliver: a set of real client questions with the correct answer written down, against which every change is measured. Without that set, "it got better" is an opinion.
And the maintenance recipes changed what I put in proposals: a document that gets replaced leaves old fragments in circulation unless someone deletes them, and the system starts answering with last year's policy. That surfaces months later, long after the demo.
What I left out
Recipes tied to specific paid services. They age quickly, and the idea underneath can almost always be built on something else.