# Retire an unreliable model; don't demote it to fallback

A generation model that fabricated a briefing claim was retired from every rung, not demoted: a fallback is a primary waiting for a bad day.

From the [Learned the hard way](../index.md#learned) section of [The Muse Field Guide](../index.md).

## The claim

That a model removed from a generation seat for fabricating output can safely stay on as the fallback.

## What happened

A seat change had moved a new model into the resident generation role, the seat that writes the morning briefing, on latency and reliability grounds. On October 21 the briefing carried a claim that was simply fabricated. The operator's ruling was not demotion; it was retirement, in his words: "Why would I want an unreliable model to ever take that work?" The model had served 5,106 metered calls in its single month in the seat. It serves no more, not as primary, not as fallback. The transferable lesson: when an agent's background output fabricates, treat it as a seat problem, not a prompt problem.

## Where this came from

The retirement was recorded in the router's tombstone, the mechanism used so a retired model errors honestly instead of being silently replaced by a default.

Related resources: [Turn judgment calls into checks over facts](verdict-rules-over-facts.md), [Spot-check every background number](spot-check-background-numbers.md)

Canonical page: https://www.niclydon.io/muse/items/verdict-unreliable-model-fallback.html