See It Work — The proven 4-agent loop — Architect, Reviewer, Executor, Tester | Book 09 · Building Multi-Agent Teams

The most proven small-team pattern is the four-agent loop: Architect (designs the smallest viable solution), Reviewer (challenges it, catching drift and bloat), Executor (builds only the approved plan), Tester (proves it works). The power is structural: four agents, four quality gates, one output examined from four independent perspectives before anything ships.

A single agent reviews its own work — and misses its own blind spots. Four independent perspectives with separate gates catch what one perspective can't, which is why this loop holds up where a solo agent drifts.

What this means for you

The four-agent loop examines one output from four independent perspectives, catching what one can't. What this means for you: you get a proven pattern that holds up where a solo agent drifts — Architect, Reviewer, Executor, Tester each gate the work from a different angle, so blind spots one perspective would miss get caught before anything ships.

Four agents, four gates, one output examined four ways:

The 4-Agent Loop

Architectdesigns the smallest solution

Reviewerchallenges drift + bloat

Executorbuilds only what's approved

Testerproves it — four perspectives

Four agents, four quality gates, one output examined from four independent perspectives.

For the technical reader — the command, and how to verify it yourself

# one line · you do not need to run this
see walkthrough

see walkthrough
# -> the Architect-Reviewer-Executor-Tester loop, four gates on one output

Full step-by-step is in Appendix RX: Hands-On Demonstrations in the book.