Lesson 14 — every production AI system has twelve components. Vendors sell one of them. Most projects fail in the other eleven. This is the map the architect uses to scope a build, defend a tier, and earn the mandate. The LLM is component number three Open any AI marketing deck and the language is…

Lesson 15 — in lesson 09 the trace was the query and the model’s answer. In production it is twelve more fields, and most of them are also the audit log. Same data; new lens. From “what did it say” to “why did it say it” Lesson 09 showed fifteen RAG traces — each one…

Lesson 16 — cost has to be measured per task, not per token. A model that’s cheap-per-token but retries ten percent of the time is not actually cheap. This is the calculator that makes the unit economics visible before you ship. Why the rate-card lies Every model provider quotes price-per-million-tokens. gpt-4o-mini is $0.15 in /…

Lesson 17 — the user never typed anything malicious. The poisoned PDF landed in the document feed last week. The retrieval pipeline did its job. The model followed instructions. The architect’s job is the validator that catches it. Indirect prompt injection — through the document, not the user Direct prompt injection — a user typing…