Pattern Quick-Reference

The decision it resolves: at a glance, what is each pattern, and should you trust it?

One row per pattern: its litmus test (new, or engineering you already knew?) and its maturity lens (standard, or hype?). Click through for the full chapter.

Stub: rows fill in and link up as chapters land.

Pattern	Who decides	Maturity
Tool use	the model	Standard
Structured output	a feature	Standard
Prompt chaining	your code (a draw)	Standard
Dispatch ("the router that isn't")	your code	Standard
Fan-out / orchestrator-workers	the model (sizes its work)	Established
Evaluator-optimizer	the model	Established
Specialist panel	the model	Emerging
Retry & graceful degradation	your code	Standard
The observer rule	your code	Standard
Multi-agent	the model	Contested

The pattern is only the vocabulary. The judgement of which one a given step actually needs, and the honesty to admit when the real answer is "this is just a retry loop", is the job.