In the Loop

One of the three collaboration modes between humans and AI agents (Outside the Loop / In the Loop / On the Loop) organized by Birgitta Böckeler, co-author with Martin Fowler. It refers to a way of working in which humans review each piece of code or output generated by an agent and directly correct any issues found.

Why It Becomes a Bottleneck

An agent can generate code in seconds, but human review takes anywhere from several minutes to tens of minutes. This asymmetry is the fundamental limitation of In the Loop. A queue of items awaiting review accumulates, making it impossible to fully leverage the agent's high-speed generation capabilities. In the author's own experience, it was not uncommon for an agent to create five PRs in 30 minutes, only for the reviews to take half a day.

When In the Loop Is Appropriate

That said, there are cases where In the Loop is effective. Infrastructure changes that directly affect production environments, authentication and authorization implementations involving security, financial or medical code subject to regulatory compliance—in these domains, the cost of having humans verify each step is worth paying. The key is to not operate everything under In the Loop. A practical balance is to apply In the Loop only to high-risk changes and shift everything else to On the Loop.