WTF is Human On The Loop?
Instead of approving every agent output, humans shape the harness that governs how agents work.
Also called: human outside the loop, why loop, how loop
TL;DR
"In the loop" means a person inspects each line the agent writes. "Outside the loop" means nobody looks. "On the loop" is the middle path: you stop reviewing every output and instead invest in the specs, checks and guidance that make outputs good, improving that system whenever something slips through.
How it works
Kief Morris separates the why loop (iterating on ideas and working software) from the how loop (iterating on code, tests and other intermediate artefacts). Humans outside the loop only work the why loop; humans in the loop gate the innermost how loop; humans on the loop build and manage the agent's harness of specifications, quality checks and workflow guidance. The term itself is older, from automation and autonomous systems, where it means supervising rather than approving each action.
Origin
- Coined / introduced by
- Kief Morris (Thoughtworks), applied to coding agents
- When
- 4 Mar 2026
- Story
- Framed in 'Humans and Agents in Software Engineering Loops' on martinfowler.com.