chapter one
1 The agent paradigm shift
This chapter covers
- Output, behavioral, and environmental uncertainties of agent systems
- How classical design patterns evolved into agent design patterns
- Why every agent pattern has an engineering ancestor
- Cognitive functions of this book's pattern language
- Building Argus, a code review agent
"The transition from a paradigm in crisis to a new one is far from a cumulative process. It is rather a reconstruction of the field from new fundamentals."
— Thomas Kuhn, The Structure of Scientific Revolutions (1962)
Recently, I watched a junior engineer debug a production outage in fifteen minutes—not by reading logs or stepping through code, but by describing the symptoms to a coding agent and letting it search, hypothesize, test, and fix. The agent tried three wrong approaches, backed off each time, and converged on the root cause: a race condition in a cache invalidation path that had survived two rounds of human code review. What struck me was not that the agent succeeded. It was that none of my twenty years of design pattern knowledge explained how to build something like it.