A diagram is not a picture. It is a data structure that happens to be visible.
Treat it as pixels and you pay pixel prices. $0.02 to $0.20 per diffusion render. No source file. No source-level way to fix a typo: you need another generation or an image-editing step.
Most teams pay this by reflex, for things that were never really pictures: diagrams, charts, dashboards, labeled boxes.
There is a second path. The LLM writes code. A renderer turns the code into the image without another model call or image-generation API fee. Generation is probabilistic, but the accepted source artifact is not. Once stored, it is repeatable, editable, and diffable.
This is the field guide I wish I'd had. Three questions, asked in order, tell you which path to take and what it will cost. The rest of the series is the evidence behind each one.
