From Prompt to Loop Engineering: Decoding the Dual-Loop Agent Architecture

Roger_M_Taylor · x · 2026-08-08

The post clearly contrasts prompt engineering with loop engineering, explaining the evolution of the underlying logic of AI agents.

The Inner Loop is Solved: At its core, an agent is simply a while loop—the model runs, requests tool calls, returns tool results to the context, and runs again until it stops. This implementation, based on the ReAct pattern, was established and solved back in 2022-23.
Automating the Outer Loop: What remains unsolved is the "loop around the loop." In common setups, the human user acts as this outer loop (writing prompts, reading turns, writing the next prompt, catching failures). Current trends attempt to let the system automate this outer loop (triggered by schedules or events), ultimately eliminating the need for constant human monitoring and intervention.

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