---
title: "Shadow mode: Definition"
description: "Running an AI system on live inputs without acting on its outputs, comparing them with human decisions before switching it on."
canonical: https://sudosapient.si/terms/shadow-mode
updated: 2026-10-27
publisher: Sudo Sapient (https://sudosapient.com/)
---
# Shadow mode

**Shadow mode:** Running an AI system on live inputs without acting on its outputs, comparing them with human decisions before switching it on.

## Why it matters

Shadow mode is the cheapest way to find out how a system behaves on real traffic without risking real outcomes. Run it for one to two weeks, compare its decisions with what people actually did, review the disagreements, and add them to the eval set. Go live only when the agreement rate meets the agreed bar.

## Related terms

- [Human-in-the-loop (HITL)](https://sudosapient.si/terms/human-in-the-loop): A design in which a person reviews, approves or corrects AI outputs at defined points, typically for uncertain or high-impact cases, with the decision logged.

## Where it comes up

- [From AI Pilot to Production: Why Proofs of Concept Stall and How to Ship](https://sudosapient.si/entries/ai-pilot-to-production)
- [Agentic AI for Business: What It Is and What Actually Works](https://sudosapient.si/entries/what-is-agentic-ai-for-business)

## In practice

Every Sudo Sapient build ships with this in place before go-live, because it is part of what separates a demo from a production system. [See how the studio works](https://sudosapient.com/).